Genetic improvement for important farmed aquaculture

Genetic improvement for important farmed aquaculture

species with a reference to carp,tilapia and prawns in Asia:achievements,lessons and challenges

Nguyen Hong Nguyen

University of the Sunshine Coast,Maroochydore,Qld 4558,Australia

Abstract

This study provides an overview of successful genetic improvement programmes for important farmed aquaculture species in Asia,with a focus on lessons and experi-ences gained as well as challenges remaining.In both ?sh and prawns (Macrobrach-ium rosenbergii ),conventional selective breeding approaches have resulted in signi?cant improvement in productivity,with genetic gains ranging from 8to 12%per generation.Selection for high growth has also brought about bene?cial changes in ?llet weight of ?sh and edible meat in prawns without detrimental effects on ?esh quality attributes and ?tness-related traits.Genetically improved animals show remarkable vigour and high adaptation to a range of culture envi-ronments/conditions in Asian countries.Despite these successes,however,the con-duct and practical implementation of such breeding programmes still present several challenges.These include the expansion of breeding objectives,manage-ment of inbreeding in closed-selection populations,controlling the effects of geno-type by environment interactions,simultaneous production of large number of full-and half-sib families for species with asynchronous spawning behaviour,maintain-ing pedigree records,dissemination of the improved strains for widespread produc-tion,as well as a reluctance by many to carry out systematically designed genetic improvement for aquatic animal species.There are also challenges with regard to the application of genomic information in genetic enhancement programmes and the development of genetically improved strains in response to climate and envi-ronmental changes.In this study,each of these challenges is discussed and solu-tions are proposed to increase ef?ciency of future genetic improvement programmes for economically important aquaculture species.

Keywords Breeding,genetics,heritability and genetic improvement,selection response

Correspondence:Nguyen Hong

Nguyen,University of the Sunshine

Coast,Locked Bag 4,Maroochydore DC,Qld 4558,Australia Tel.:

+61754565138Fax:

+61754565150E-mail:NNguyen@https://www.doczj.com/doc/118300351.html,.au

Received 7Nov 2013

Accepted 14Apr 2015

Introduction

2Examples of successful genetic improvement in carp,tilapia and prawns 3Carp 4Tilapia

5Giant freshwater prawn 6Challenges

6Biological constraints

7

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F I S H and F I S H E R I E

S

Family production in tilapia and prawns7 Mating design in carp,tilapia and prawns7 Family and individual identi?cation in prawns7 Molecular-based pedigree in carp,tilapia and prawn8 Social interactions and indirect genetic effects9 Correlated responses to selection for high growth9 Multitrait selection10 Genotype by environment interaction11 Management of inbreeding13 Estimation of genetic gain14 Climate change14 Gene(maker)-assisted selection and genomic selection16 Dissemination of improved strains17 Capacity to run genetic improvement programmes17 Other issues18 Conclusions18 Acknowledgements19 References19

Introduction

Asian aquaculture accounts for about80%of total world production,but it will need to grow sub-stantially to meet the demands of a rapidly expanding human population(FAO2012).One way to increase the production of cultured species, per unit of land and water use,is through genetic improvement.By way of comparison,most of the improvement in land agriculture(livestock and crops)over the last half century has been as a result of the development and use of genetically superior breeds or varieties(Hill2008).For exam-ple,growth rate in chickens increased by about 300%with more than90%of that improvement being directly attributable to genetic selective breeding(Havenstein et al.2003).On the other hand,there are only a few examples where aqua-culture production has bene?ted from genetically improved strains such as Atlantic salmon(Gjed-rem2012).

There is also the issue of loss of productivity from poor genetic management and inbreeding. Aquaculture seedstocks are often collected periodi-cally from the wild and,if bred in captivity over generations,are seldom adequately managed from a genetic viewpoint(Eknath and Doyle1990; Ponzoni et al.2010).Without proper manage-ment,the usual outcome for highly fecund aqua-culture species is loss of genetic diversity as a consequence of inbreeding,leading to a decline in productivity,and there are many instances in which‘domesticated stock’have proved to be less productive than their counterparts from the wild, due to?tness reductions(Araki et al.2008). Across the sector,the lack of improved strains capable of producing high-quality seed is consis-tently identi?ed as the most widespread and persis-tent technical obstacle to the sustainable development of aquaculture among both small and medium enterprises(FAO2012).In response to this situation,a number of breeding pro-grammes have been initiated to develop genetically improved strains and enhance quality seed produc-tion for important farmed aquatic species in Asia (Nguyen and Ponzoni2006).Despite intermittent reports of success(Hung et al.2013b;Ninh et al. 2013;Hamzah et al.2014b),there are many remaining problems to be resolved prior to the implementation of improved selective breeding pro-grammes.Key challenges include biological limita-tions,genetic selection and mate allocation strategies,the effects of the environment on geno-type stability,particularly in response to climate change,as well as the adoption of the improved strains by end-users(N.H.Nguyen,unpublished data).This study focuses on three species(carp, tilapia,giant freshwater prawn Macrobrachium ro-senbergii,Palaemonidae)chosen due to their high socioeconomic importance and large production volumes in Asia(FAO2012).We will emphasize the many existing challenges to the industry and

2?2015John Wiley&Sons Ltd,F I S H and F I S H E R I E S Genetic selection in carp,tilapia and prawns N H Nguyen

attempts to provide solutions to overcome these using breeding programmes.Many of these issues apply to other aquaculture genetic selection pro-grammes.Suggestions for future studies are pre-sented.

Examples of successful genetic improvement in carp,tilapia and prawns

Formal genetic improvement programmes have been established for carp,tilapia and Giant fresh-water prawn in a number of Asian countries (Ponzoni et al.2011;Hung et al.2013a;Ninh et al.2013;Hamzah et al.2014b).The general experimental design for these species is presented in Fig.1,but it is usually adjusted to ?t biology and production cycle of individual species during practical implementation.Brie?y,in each genera-tion,between 50and 100full-and half-sib fami-lies are produced,following hierarchical nested (e.g.one male mated to two females)or partial factorial mating design (e.g.male 1with females 1and 2,male 2with females 2and 3,and so on to male n with female 1and n ).Natural spawning (taking place in hapas (ponds)without outside intervention or induced breeding (with hormonal treatment)is applied to synchronize reproduction within as short a time interval as possible.Individ-ual families are reared separately until the fry reach a suitable weight to be physically tagged (5–10g for ?sh and 2–5g for prawns).Communal grow-out for performance testing is then con-ducted in the prevailing culture environments:normally earthen ponds.At harvest,body mea-surements,in addition to other important traits (sexual maturity,survival),are recorded.The data are then processed,using best linear unbiased pre-diction (BLUP)methodology to determine genetic merits (or estimated breeding values,EBV)for each individual in the pedigree.The highest EBV animals are selected to become parents of the next generation.A combined between-and within-fam-ily selection was applied,and matings made among genetically unrelated brood stock,based on an individual’s EBV and genetic relationship to other animals in the pedigree.The same

Tagging 50 –70 pcs/ family

5000 ?sh

4 – 6 months

Gene?c evalua?on

and selec?on

Selected breeders

Nursery 4–8 weeks

Hatchery Condi?oning of breeders

Mate alloca?on

Grow-out system

60 –100 families

♂

♀

with DNA tagging

Early communal rearing

Figure 1General design of genetic improvement programmes for farmed aquaculture species.The production cycle of

tilapia (about 1year per generation)is given as an illustrative example.Photograph courtesy:Azhar Hamzah and WorldFish.

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procedures regarding family production,genetic evaluation and selection process are repeated in subsequent generations during the course of the project.In all of the above programmes,genetic improvement has focussed on the enhancement of production performance(i.e.body weight).In some cases,as the programme proceeds,economi-cally important traits(carcass trait,?esh quality,?tness-related traits–such as survival and repro-duction)are also investigated and possibilities for broadening the breeding objectives of target spe-cies are considered.The experimental design described above is generally also used for other aquatic animal species(Rye et al.2010).

Carp

Carp is the most important freshwater?sh,con-tributing about41.6%to total world aquaculture production(FAO2012).Several species of carp have been widely cultured in South and South-East Asian countries.Selective breeding pro-grammes have been carried out in important spe-cies such as silver barb(Puntius gonionotus, Cyprinidae)in Bangladesh and Thailand(Hussain et al.2002),rohu(Labeo rohita,Cyprinidae)in India(Gjerde et al.2002;Mahapatra et al.2007) and common carps(Cyprinus carpio,Cyprinidae)in China,Indonesia and Vietnam(Ninh et al.2011). The majority of these countries have established systematic genetic improvement programmes,and fully pedigreed populations are maintained by?t-ting an individual animal model to estimate genetic merit and select replacements.This enables rigorous conduct of the genetic improvement pro-gramme as well as the necessary control of inbreeding to secure long-term response to selec-tion.Across carp species examined in this study, genetic gain ranged from8to20%per generation (Table1).There is also considerable genetic varia-tion in these populations,with the heritability for body weight ranging from0.20to0.40(Table1), providing valuable stock for future selection. Although selection was primarily for harvest weight,correlated increases in body length,height and width were also achieved in carp species (Ninh et al.2013).The establishment of a fully pedigreed population is fundamental in broadening the breeding objectives for some carp species,for instance by including additional new traits such as survival or disease resistance in rohu(Mahapat-ra et al.2008)or applying new molecular genetic technologies for parental assignment in common carp in Vietnam(Ninh et al.2011).Parentage assignment using microsatellite markers enables the early communal rearing of all families from birth as a means of reducing common environ-mental effects,achieving faster growth rates(thus shortening the time to selection)and,as a conse-quence,accelerating the development of bene?cial genetic traits in the population as a whole(Ninh et al.2013).

The selected carp strains developed from these programmes have demonstrated signi?cantly greater growth performance than local stocks of the same species,ranging from20to40%across agro-ecological regions and farming systems in Bangladesh,Thailand and Vietnam(Nguyen and Ponzoni2008).The marked improvement of the ‘Jayanti’rohu carp relative to local strains(up to 75%)was also recorded in a range of culture envi-ronments in India(Mahapatra et al.2007).Due to the superior performance of the improved strains, there has been a growing demand for the improved carp seed in major carp producing coun-tries where these improved varieties have signi?-cantly increased the productivity and pro?tability of carp producers(Dey et al.2010).The economic bene?t and bene?t-to-cost ratio from the genetic improvement programme in carp has been highly bene?cial(Ponzoni et al.2008)to national econo-mies,especially in countries where a pyramid

Table1Heritability(?average standard errors)for body weight and genetic gain(%)achieved in carp species in Asia.

Latin name Common

name

Generation

of selection Heritability

Genetic gain

per generation(%)References

Cyprinus carpio,Cyprinidae Common carp30.25–0.32(?0.06)10.0Ninh et al.(2013) Labeo rohita,Cyprinidae Rohu50.23?0.0617.0Mahapatra et al.(2007) Puntius gonionotus,Cyprinidae Silver barb30.207.2Hussain et al.(2002)

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breeding structure (two or three tiers including nucleus,multiplication and production)(Nguyen and Ponzoni 2006)is well established to dissemi-nate the improved genes from the nucleus,either directly or indirectly,to commercial producers such as in India and Vietnam (K.Mahapatra and N.H.Ninh,personal communication).Tilapia

Tilapia is the second most important freshwater ?sh after carp,and a number of improved strains have been developed by national aquaculture institutions in Asia.In this study,I present the example of the genetically improved farmed tilapia (GIFT)strain that has involved major international and regional efforts by The WorldFish Center as well as Norwegian,Philippine and Malaysian insti-tutions.The GIFT base or foundation population was established in early 1990s (Eknath et al.1993,2007;Bentsen et al.1998).Prior to 1996,these ?sh went through six generations of selec-tion for high growth in the Philippines (Bentsen et al.2012).In 2001,the GIFT strain was trans-ferred to a research station operated by the Department of Fisheries,Malaysia.Since then,the selection programme has been continuing (Ponz-oni et al.2005),and by 2013,the GIFT ?sh had undergone 16generations of selection (Nguyen et al.2010b;Ponzoni et al.2011;Hamzah et al.2014b).There has been substantial improvement in growth performance of the GIFT strain over the course of selection,with an average gain of 10%per generation (one generation per year in tilapia)combining to produce body weights more than double when compared with the control over 10generations of selection (Fig.2)(Hamzah et al.2014b).Moreover,restricted maximum likelihood (REML)estimates of heritability for body weight (h 2=0.28)in the latest generation (2012)indi-cated that there is still genetic variation in the population to encourage additional selective breed-ing to achieve further increases in body weight.To date,the GIFT strain has been distributed and cultured in 14different Asia –Paci?c (China,Bangladesh,Indonesia,Philippines,Papua New Guinea,Sri Lanka,Thailand,Vietnam)and Latin American (Brazil,Costa Rica,Ecuador and Mexico)nations.The ?sh have performed well in many dif-ferent farming systems.For example,in Sri Lanka,the GIFT strain exhibited a 112%increase in body weight at harvest compared to local varieties across three different production environments:ponds at the government research station,ponds of farmers and seasonal reservoirs.In addition,survival rates of GIFT were 8.2–23.8%higher than local stocks (Nguyen et al.2011a).Under commercial production,culture of monosex (sex reversed or YY male)GIFT strain is widely prac-tised in the region (Kamaruzzaman et al.2009).Not surprisingly,the GIFT strain has had a very large impact on production volumes.As a conse-quence,the livelihoods of farmers in many Asian countries has been improved and there has been a considerable positive socioeconomic impact accord-ing to the Asian Development Bank (ADB 2005)

01234560

20406080100120200320042005200620072008200920102011

G e n e t i c s t a n d a r d d e v i a t i o n U n i t

P e r c e n t a g e o f t h e c o n t r o l , %Genetic SD Unit

%

Figure 2Genetic trend for body weight in the genetically improved farmed tilapia (GIFT)strain over 10generations of selection in Malaysia (Hamzah et al.2014b).Genetic standard deviation unit =estimated breeding values in actual measurement unit/r A where r A is the square root of the additive genetic variance.

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and the International Food Policy Institute(Yosef 2009).This is a highly successful example of genetic improvement in farmed aquaculture.GIFT has become a model species,and the associated technologies(GIFT Manual)have been applied to improve other indigenous tilapia such as Oreochr-omis sharinus,Cichlidae in Malawi(Maluwa et al. 2006),Nile tilapia Oreochromis niloticus,Cichlidae in Egypt(Rezk et al.2009)and red tilapia Oreochr-omis spp.,Cichlidae in Malaysia and Thailand (Hamzah et al.2008;Pongthana et al.2010; Nguyen et al.2011b).

Freshwater prawn

Genetic improvement of the giant freshwater prawn (GFP),M.rosenbergii,was only initiated in2007, after the successes of breeding genetically improved strains of farmed tilapia and carp became better known.GFP is one of the most important crusta-ceans in inland aquaculture in the(sub)-tropics and ?ts in well to the typical Asian smallholders’system of prawn polyculture along with carp or tilapia (Zimmermann et al.2010).Selective breeding has begun in China(Luan et al.2012),India(Pillai et al.2011)and Vietnam(Thanh et al.2009;Hung et al.2013b).The main aim of such programmes is to develop high-yielding strains with good adapta-tion and high survival rates under culture condi-tions in Asia.Implementation of the programmes started with the collection and evaluation of geo-graphically discrete populations in each country (India,Malaysia or Vietnam).We performed a full diallel cross involving three different strains to cre-ate a synthetic base population for systematic stock improvement.Statistical analysis of the diallel crosses showed that the additive genetic and reci-procal effects were the major signi?cant sources of variation for all growth traits,whereas the heterosis effect was not signi?cantly different from zero (Thanh et al.2010;Pillai et al.2011).A synthetic base population was formed from the best perform-ing individuals regardless of their genetic make-up. Selection based on additive genetic effects has been practised in these populations because cross-breed-ing among existing strains is likely to result in only marginal genetic superiority due to the small mag-nitude of the heterotic effects(Thanh et al.2010). Mixed model estimation of genetic parameters showed that there is heritable genetic variation in the selection population,with heritability ranging from8to41%across a number of body traits (Hung et al.2013a).Selection also resulted in signi?cant direct response in harvest weight(aver-aging7%per generation i.e.per year)and simulta-neously brought about bene?cial gains to carcass traits such as abdominal length,abdominal weight, telson-off weight and skeleton-off weight(3–4%per generation)(Hung et al.2013b)(Box1).

Challenges

Despite the successes,there are several challenges remaining relating to the practical

implementation 6?2015John Wiley&Sons Ltd,F I S H and F I S H E R I E S Genetic selection in carp,tilapia and prawns N H Nguyen

of genetic improvement programmes for carp, tilapia and prawns.In the following sections,each of the challenges is discussed with particular empha-sis on how they can be accommodated to improve the ef?ciency of genetic breeding programmes.

Biological constraints

Family production in tilapia and prawn Simultaneous production of a large number of families still remains a challenge for species with asynchronous spawning behaviours and in species where induced breeding is not possible,for exam-ple tilapia and freshwater prawn.In these species, females do not often reach sexual maturity or spawn at the same time.In addition,for M.rosen-bergii,there is a high rate of egg clutch abortion, about30–40%(Thanh et al.2009,2010),and in breeding programmes,it often takes1–2months to produce between50and100families:the sam-ple size required to constrain the inbreeding rate to<1%per generation.Prolonged spawning inter-vals,accompanied by the rearing of separate fami-lies,can lead to large differences,not only in stocking weight,but also to differences in ambient environmental conditions among full-sib groups (Nguyen et al.2007;Ponzoni et al.2011;Hamzah et al.2014b).To obtain a large number of families per generation within a short time,it is advisable to use excessive numbers of mating hapas(net cage)or tanks,although the minimum quantity will vary by species.In species with asynchronous spawning behaviours,such as tilapia,in-vitro fer-tilization(IVF)can help to shorten the spawning interval,allowing the design of alternative advanced mating schemes.

Mating design in carp,tilapia and prawns Application of advanced mating schemes,such as factorial design,is still dif?cult in tilapia and GFP. Classical nested mating design(one male to two females)is usually practised in tilapia and prawns. However,at the same effective population size (N e),factorial mating can achieve a greater accu-racy in parameter estimation and selection response compared with conventional single pair or nested mating design(Dupont-Nivet et al. 2006).When compared with nested designs,facto-rial matings increase the number of half-sib fami-lies while decreasing the number of full-sib families,thus reducing the risk of selecting many individuals from the same parents(Sorensen et al.2005).The single pair mating design is best in terms of maximizing effective population size(N e), which is necessary to secure long-term genetic response to selection(Dupont-Nivet et al.2006). However,in shallow full-sib pedigreed populations, it is dif?cult to separate the additive genetic com-ponent of variance from dominance and common environmental effects in single pair matings. There are four main types of factorial mating designs:complete,incomplete,by set and rectan-gular factorial(Berg and Henryon1998);each has advantages and disadvantages.For instance, complete factorial mating can produce a popula-tion with both paternal and maternal information, but results in a very large number of families (s9d families where s is the number of sires and d is the number of dams),which may be dif?cult to accommodate in practical programmes.The fac-torial mating by set compromises the number of families produced(from a reasonably large number of parents)and the availability of facilities allo-cated to breeding programmes.In all schemes,fac-torial matings require the use of in-vitro fertilization procedures and arti?cial incubation systems.However,the facilities are relatively sim-ple and the procedures have been successfully implemented in the common carp breeding pro-gramme in Vietnam(Ninh et al.2011).

Family or individual identi?cation in prawns

In addition to the production of families in a con-trolled manner(pair mating or external fertiliza-tion),the progeny of the different families must then be identi?ed in some way so that they can be communally stocked and tested for genetic evalua-tion and selection purposes.Passive integrated transponder(PIT)tags have been used widely and successfully for individual identi?cation in carp and tilapia,but their use is more dif?cult with crustaceans.For example,in the giant freshwater prawn,M.rosenbergii,there are two major issues, especially with regard to individual identi?cation. In prawns,physical tagging is much more dif?cult than in?sh species,due to small body size,and periodical moulting.Hung et al.(2012)have eval-uated different tagging methods:VIE(visible implant elastomer),VIA(visible implant alpha-numeric tag),eye tags and PIT tags.VIE is from Northwest Marine Technology(NMT)and is pro-vided in liquid form with10different colours.Five ?uorescent colours(orange,green,blue,yellow and pink)are suitable for tagging freshwater

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prawn.We have successfully tagged1–2g prawns at four different positions:on the left and right of the?rst and?fth abdominal segments.After a grow-out period of120day,the retention rate was98%and readability was100%(Hung et al. 2012).Given these?ve colours,four tagging posi-tions and multiple tags,we can tag up to256 families.If all10colours are used,600families can be tagged.The second tagging system tested was visible implant alpha(VIA),also from NMT. VIA is manufactured from soft polyester with unique numbers(the standard format being ~1.592.5mm).Tagging is straightforward but time-consuming(100prawns per hour for a skilled worker).The tag can be implanted through the hinge membrane of the second abdominal somite of1–2g prawns.The retention rate after grow-out(78%)was lower than VIE tags although readability was98%(Pillai et al.2009).Eye tags are generally unsuitable due to the short eye stalk of freshwater prawns;however,they can be used as a secondary tagging system to mark individuals at harvest.In combination with VIE,a full pedi-gree population has been maintained for this spe-cies in Vietnam.PIT tags are excellent for individual identi?cation in?sh,but there are four major problems when tagging freshwater prawn: (i)tag migration from the abdomen to the head, (ii)low retention rates,(iii)injury and pigmenta-tion and(iv)dif?culty in tagging small prawns.In summary,VIE and VIA can be used effectively to maintain pedigrees for M.rosenbergii because they meet the four essential criteria:(i)individual iden-ti?cation at an early age(1–2g),(ii)high reten-tion(98%for VIE and78%for VIA)and readability rates(100and98%,respectively),(iii) easy and inexpensive to apply and(iv)harmless to the prawn and the consumer.Both VIE and VIA have been found to have negligible effect on growth and survival(Pillai et al.2009;Hung et al. 2012).

Molecular-based pedigree in carp

Maintaining pedigree information is very impor-tant in aquatic animals.Due to the small size of newly born?sh and prawns,it is not possible to tag them after hatching and families need to be maintained separately until they reach a suitable size for physical tagging.Separate rearing of indi-vidual families before tagging also induces envi-ronmental(i.e.hapa or tank)effects common to full-sib families.This problem can be overcome using DNA markers for parentage assignment. With genetic tagging,all families can be pooled and sent to communal rearing as soon as practica-ble after hatching.Parentage testing and pedigree veri?cation with genetic tagging has four main advantages:(i)increasing the number of families tested without the need for extra tanks and ponds, (ii)reducing the effects common to full-sibs,(iii) shortening generation intervals(?sh attain sexual maturity earlier than expected under early non-communal rearing as early communal rearing reduces the need for hapas that do not,in general, provide a favourable growing environment for juvenile?sh,especially carp species)and(iv)mini-mizing the interaction between the selection and production environments as the animals can be grown under full commercial conditions.Conse-quently,DNA tagging has the potential to assist in increasing genetic gain(Ninh et al.2013).Both experimental and theoretical results show that using8–14microsatellite markers,progenies can be assigned to parents with a high degree of accu-racy(90–99%)for many aquatic species(Villanu-eva et al.2002).DNA?ngerprinting is increasingly employed for genetic tagging in com-mercial breeding programmes of farmed aquacul-ture species(Estoup et al.1998;Fishback et al. 2002;Vandeputte et al.2011;Whatmore et al. 2013).

Ninh et al.(2013)compared communal early rearing(CER)and separate early rearing(SER) schemes for common carp.The?sh under the CER scheme grew faster and achieved greater genetic gain than under SER(Ninh et al.2011,2013). The superiority of CER relative to SER demon-strated potential bene?ts of molecular parentage assignment as a useful tool in practical selective breeding programmes.Although the current costs of genotyping are high,they are expected to decline signi?cantly with the development of DNA chips where thousands of single nucleotide poly-morphisms(SNPs)can be genotyped simulta-neously.SNPs can be used successfully to replace microsatellites for the purposes of parentage assignment and pedigree veri?cation due to their lower error rate in comparison to microsatellite markers(Tr?ng et al.2013b).However,two to eight times more SNPs than microsatellites are required to obtain the same power of successful assignment for traceability(Weller et al.2006;Ha-user et al.2011).Despite the advantages of genetic tagging,the technique does not completely

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replace physical tagging because,at the time of tissue sample collection made for DNA analysis, the animals still need to be physically tagged for identi?cation,genetic evaluation and selection.

Social interactions and indirect genetic effects in prawns

In farmed aquaculture species,behavioural inter-actions are associated with two main conse-quences:cannibalism and social structure.In?sh, cannibalism often occurs during the early rearing stage(Hecht and Pienaar1993),whereas in crus-taceans,this phenomenon is normally observed pre-or intermoulting(Wall et al.2009).Generally, cannibalism can be minimized through improving management practices such as providing suitable shelters for moulting prawns or reducing stocking density.Other solutions include provision of ade-quate feed and ensuring its even distribution in grow-out ponds.Gomez Diaz et al.(1990)sug-gested ablating the immobile?nger of the claw (propodus)to prevent cannibalism although,from a genetic viewpoint,it is worth examining the social interaction effects in crustacean species to maximize yield and productivity for the sector. Recent studies in farmed animals have shown that there is an additive genetic component for traits affected by competitive interactions(e.g.survival and growth).The moderate heritability for social traits(0.10–0.40)(Ellen et al.2014)suggests pos-sibilities to select for both the ability of each indi-vidual to grow and a competitive behaviour conducive to the well-being and growth rate of other individuals sharing the same environment. Bijma et al.(2007)have developed a theoretical framework to account for competitive interactions in selection programmes.However,there have been no such studies in?sh or in any other aqua-tic animal species and this area of research deserves serious consideration.

An example where social population structure has profound effects on growth and morphology is in the giant freshwater prawn,M.rosenbergii.This species is unique with males classi?ed into three different morphotypes:blue,orange and small claws.Blue-claw males are aggressive,dominant and territorial;orange-claw males are subdomi-nant and non-territorial;and small-claw males are submissive.It has been well documented that male prawns show18different antagonistic behaviours among morphotypes(Barki et al.1991),with blue-claw males suppressing the growth of the other forms(Karplus2005).This causes a large difference in body weight among morphotypes, and as a result,the distribution for this trait is markedly skewed.Logarithmic or square root transformation improved distribution of the data and accuracy of genetic parameter estimates.It is, therefore,important to record morphotype data in practical breeding programmes and include them in statistical models for genetic evaluation.With the omission of male morphotype in statistical models,estimates of genetic parameters and breed-ing values were biased upward or overestimated from25to40%(Hung et al.2013a,b).Given the existence of a heritable(additive genetic)compo-nent for male morphotypes,there is scope for genetic selection to change the population struc-ture of M.rosenbergii to minimize possible social interaction effect in future genetic improvement programmes for this species(Hung and Nguyen 2014).Managing the adult male morphotypes, population structure and antagonistic behaviour can be combined with single sex(all male)grow-out cohorts to increase total biomass yields, thereby signi?cantly increasing farm returns.

Correlated responses to selection for high growth

Due to pleiotropic effects[i.e.the effect of one gene (or a set of gene)on multiple trait expression], selection for one character may lead to correlated changes in the others(Falconer1981).There are a number of studies to measure correlated changes in quality and?tness traits of aquaculture species. One example is that of the GIFT strain,where a series of experiments were conducted to examine the effects of selection for increased performance on?esh quality attributes.The results from these studies demonstrated that selection for high growth in GIFT has resulted in a simultaneous sig-ni?cant increase in?llet weight(Nguyen et al. 2010b).The accumulated response in?llet weight up to the latest generation of selection in the spawning season2008was23%(Nguyen et al. 2010b).In contrast to?llet weight,correlated changes in?llet yield were non-signi?cant.These ?ndings are consistent with those reported in farmed terrestrial animals(Koch1978;Nguyen and McPhee2005).Mixed model analyses also found that?esh composition traits(protein,fat, moisture content)and two important?esh quality parameters(pH and colour)in the selection line did not differ from the control(Nguyen et al.

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2010a).A subset of GIFT?llet samples was randomly chosen for fatty acid(FA)analysis using gas chromatography.Nguyen et al.(2010c) reported that there were no major changes in FA composition as a consequence of the long-term selection for high growth in the GIFT strain.While this is partially explained by the non-signi?cant difference in?llet fat content between the selection and control lines,the negligible changes in FA composition of GIFT indicate that selection for high growth has had a very limited impact on FA composition and?esh quality.However,close monitoring of correlated changes resulting from selection for high productivity is recommended in future breeding programmes.Strategies for genetic improvement of?esh quality traits are discussed by Gjedrem(1997)and Nguyen et al.(2010a).

In addition to?esh quality,?tness-related traits (i.e.fecundity,number of surviving fry,fry weight) were also examined in the GIFT strain.Hamzah et al.(2014a)report that the correlated changes in reproductive traits(female weight,number of fry at hatching,total fry weight,fry viability)mea-sured as differences in least square means between selection and control lines were all signi?cant when the body weight of females prior to spawn-ing within line was not?tted as a covariate.Differ-ences in reproductive traits between lineages were 41%for total fry weight or62%for the weight of females prior to spawning.An improvement in hatching rate was also observed where fry mortal-ity was reduced by16.3%in the selection line rel-ative to the control.However,differences in reproductive performance between the selection and control lines were not signi?cant when the body weight of females before spawning within line was?tted as a covariate in analysed models. This suggests that reproductive performance per unit weight of female did not change as a conse-quence of selection for high growth.These results are consistent with a general pattern found in farmed animals or other laboratory species where there are negligible effects on reproductive perfor-mance to selection for increased body weight or high growth rate(B€u nger et al.2005).By con-trast,breeding objectives that place strong empha-sis on ef?cient lean production have been found to negatively impact the productivity of females(Kerr and Cameron1995).

Whereas there are limited changes in?esh qual-ity and reproduction traits from selection on body weight,unfavourable correlated responses may occur in animal behaviours in the long term (Olsen and Moland2011).Shehzad(2009)reports epicarditis and the incidence of heart abnormali-ties in farmed Atlantic salmon as a correlated response in the genetic improvement programme for high productivity in Norway.Higher growth hormone levels in faster growing?sh have also been correlated with increased aggression in some ?sh(J€o nsson et al.1998),which may have nega-tive environmental consequences in the event of farmed?sh escape.Undesirable effects on traits of economic importance were also found to be associ-ated with selection for high productivity in terres-trial farmed animals(Rauw et al.1998).Under these situations,a desired gain selection index approach can be used to simultaneously improve traits as demonstrated in yellowtail king?sh Seriola lalandi,Valenciennes(Nguyen et al.2015).In con-clusion,it is recommended that economically important traits should be included in the record-ing scheme,breeding objective and selection index to ensure the sustainability of long-term genetic improvement programmes for aquaculture species. Alternatively,they should be at least closely moni-tored in breeding programmes.

Multitrait selection

In the long term,multitrait selection is desired as it not only avoids undesired changes in traits but also maximizes revenue and productivity resulting from genetic improvement programmes.One example can be shown in Atlantic salmon where the breed-ing objectives for this species included a range of traits from growth performance to disease resistance (Gjedrem2010).To date,the breeding of carp,tila-pia and freshwater prawns has mainly only focussed on improving body weight,as it is related to food security and,currently,?sh and prawns are priced on the basis of whole body weight in these countries(Nguyen et al.2010b).The selection for a single trait in the majority of breeding programmes for farmed aquaculture species contrasts sharply to the farming of terrestrial animals,such as dairy cat-tle,where the breeding objectives may include as many as14different traits(Miglior et al.2005). Many of the dif?culties associated with the improve-ment of aquatic animals are due to:(i)a lack of ef?-cient methods to enable the routine recording of data on a large scale for?tness and functional traits; (ii)a paucity of scienti?c knowledge about genetic variation and relationships among production,

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reproduction and adaptive traits;and(iii)a lack of recording systems for variable and?xed production costs in aquaculture to derive economic values (Nguyen et al.2010a).

In addition to the efforts made to resolve chal-lenges highlighted above,we considered possibili-ties to broaden the breeding objectives in tilapia and carp by examining the genetic inheritance of new traits such as carcass yield,?esh quality and fatty acids as well as?tness-related traits,such as reproductive performance(Fig.3).Our estimates of heritability show that there is additive genetic variation involved in all traits studied including fat content,polyunsaturated and essential fatty acids (omega-3and omega-6)(Nguyen et al.2010a,c). This suggests that there are prospects for genetic improvement of these traits although their inclu-sion in the breeding objectives may be resisted mainly due to the lack of payment systems that reward producers(Nguyen et al.2010a).One may argue that the inclusion of these traits is only jus-ti?ed if?sh producers are paid not only for live body weight but also?esh and eating quality attri-butes.In addition to quality characteristics,it is still necessary to include?tness and functional traits in the selection programmes for aquaculture species.Both allocation resource and selection the-ories,assuming that resources expended for one function are less available for other functions, suggest?tness-related traits(e.g.fertility,survival)may show a tendency to decline due to selection for other traits and/or inbreeding depression(God-dard2009).Therefore,a multitrait index selection would help ensure the sustainability of long-term genetic improvement programmes for aquaculture species.Separate breeding objectives and selection indices should also be developed and customized to particular production scenarios and marketing goals even though it is not a simple matter to establish breeding objectives that satisfy all market needs.Attempts to forecast the market are prone to errors caused by changing fashion(N.H. Nguyen,unpublished).The limitations of biology ensure that genetic improvement generally occurs at a slow rate and therefore cannot usually respond quickly to changes in market trends.With well-established industries,a range of breeding objectives targeting different niche markets has been success-fully practised,for example beef cattle in Australia (Barwick and Henzell2005).Hence,this area of research merits the further consideration in practi-cal selective breeding programmes to meet future demands of the aquaculture industry.

Genotype by environment interaction(G9E)

Considerable research has been conducted globally and regionally(Table2)to examine the effects of genotype by environment(G9E)interaction as there is a growing concern that genetic lines

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selected in the nucleus may not perform well under commercial production.The general trend reported in the literature across aquaculture spe-cies–?sh,crustaceans and mollusc(Table2)–is that the genetic correlations for the expressions of body weight were very high,close to1.0,between ponds and cages(Bentsen et al.2012)or between ponds(or cages)vs.integrated crop-livestock and ?sh systems(Tr?ng et al.2013a).However,when the testing environments differ,genetic correla-tions for homologous body traits have been low, for example between freshwater and brackish water(Luan et al.2008;Chiasson et al.2013)or between countries(Sae-Lim et al.2013).Overall, the average genetic correlation between‘similar’environments is high,indicating that G9E inter-action is unimportant for body weight across most aquaculture species(Table2),thereby negating the requirement to conduct separate breeding pro-grammes for speci?c environments.However, when the environments in questions are markedly dissimilar,G9E interactions can be biologically signi?cant,especially for traits with low heritabil-ity such as sexual maturity or?tness-related

Table2Genetic correlations(r G)between the expressions of body weight between contrasting grow-out environments. Reference Common name Latin name Environments r G*

Sylv e n et al.(1991)Rainbow Trout Oncorhynchus mykiss,

Salmonidae

Freshwater vs.salt water0.72

Winkelman and Peterson(1994)Chinook Salmon Oncorhynchus tshawytscha,

Salmonidae

Freshwater vs.salt water0.75

Fishback et al.(2002)Rainbow Trout Oncorhynchus mykiss,

Salmonidae

8.5°C vs.15.5°C0.86

Kause et al.(2003)Rainbow Trout Oncorhynchus mykiss,

Salmonidae

Freshwater vs.brackish water0.95 Gitterle et al.(2005)Shrimp Penaeus vannamei,Penaeidae Pond vs.tank0.79 Maluwa et al.(2006)Tilapia Oreochromis shiranus,Cichlidae Low vs.medium vs.high

altitude

0.77 Kolstad et al.(2006)Atlantic cod Gadus morhua,Gadidae4locations0.89 Swan et al.(2007)Oysters Crassostrea gigas,Ostreidae5locations0.91 Quinton et al.(2007)White?sh Coregonus lavaretus,Salmonidae Fish vs.soya bean meal0.97 Eknath et al.(2007)Nile tilapia Oreochromis niloticus,Cichlidae7environments0.77 Luan et al.(2008)Tilapia Oreochromis niloticus,Cichlidae Freshwater vs.salt water0.45 Ibarra and Famula(2008)Shrimp Liptopenaeus vannamei,

Penaeidae

Low vs.high density0.61

Dupont-Nivet et al.(2008)Sea bass Dicentrarchus labrax,Moronidae Four countries0.89 Pierce et al.(2008)Rainbow Trout Oncorhynchus mykiss,

Salmonidae

Fishmeal vs.plant diets0.73

Khaw et al.(2009)Tilapia Oreochromis niloticus Low vs.high inputs0.81 Ninh et al.(2011)Common carp Cyprinus carpio,Cyprinidae Communal vs.separate

rearing

0.84 Khaw et al.(2012)Tilapia Oreochromis niloticus,Cichlidae Pond vs.cage0.79

Tr?ng et al.(2013a)Tilapia Oreochromis niloticus,Cichlidae Pond vs.cage0.94

Le Boucher et al.(2013)European seabass Dicentrarchus labrax,Moronidae Marine products vs.plant-

based diet

0.78–0.93 Domingos et al.(2013)Barramundi Lates calcarifer,Latidae Intensive vs.semi-intensive0.99

Freshwater vs.sea cage

water

0.97

Mas-Mu~n oz et al.(2013)Common Sole Solea solea,Soleidae Recirculation system vs.semi-

natural pond

0.42 Chiasson et al.(2013)Arctic charr Salvelinus alpinus,Salmonidae Freshwater vs.sea cage

water

0.50

Sae-Lim et al.(2013)Rainbow Trout Oncorhynchus mykiss,

Salmonidae

USA vs.Germany vs.Peru0.26 Average across studies0.78

*Mean across statistical models and environments(or countries).The average SE=0.14.

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characters(Kause et al.2003).To minimize the possible impacts of G9E effects in practical selec-tive breeding programmes,the choice of the selec-tion environment to be tested should be as close to actual production conditions as possible.Consis-tent measurements should be made across the environments being compared.Alternatively, selection for a combination of performance in both environments should be applied(De Jong and Bi-jma2002).For this approach,a selection index can be applied by treating the expression in each environment as a separate trait and weighting the traits in proportion to the relative importance of production environments in a particular country or enterprise.Understanding phenotypic plasticity and reaction norms to minimize the G9E effect in selective breeding programmes for aquaculture species is another area meriting future study (Box2).

Management of inbreeding

Management of inbreeding in a closed-selection population is critical to maintain genetic variability (Knibb et al.2014)and ensuring long-term responses to selection.Full pedigree information also enables more effective management and the control of inbreeding using genetic approaches and advanced statistical analysis.In pedigreed popula-tions of tilapia,carp and prawns,a combined between-and within-family selection(i.e.selecting a limited number of individuals per family and hav-ing representatives of as many families as possible in future generations)was employed to minimize the accumulation of inbreeding(Hung et al.2013a; Hamzah et al.2014b).In addition,matings between full-and half-sibs were avoided in these species(carp,tilapia and prawn).These strategies limit the overall level of inbreeding to an acceptable level,but not the additive genetic relationships among individuals in the population.In the long term,a combination of both selection and mating strategies are required to manage genetic gain and restrict the accumulation of inbreeding.This method uses a quadratic index to weigh/assess the genetic contribution of individual breeders in the population to future generations.Jointly used with BLUP,the so called optimal genetic contribution theory can maximize genetic gain while minimizing the level of inbreeding(Meuwissen1997).Com-puter simulation studies have shown an increase in selection responses between20and60%would be expected compared with the standard BLUP meth-odology(Sonesson and Meuwissen2000).For example,Kinghorn(2011)found a40%increase in response to optimal genetic selection and a

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reduction in the level of inbreeding after30genera-tions.By applying mate allocation that is based on estimated breeding values and pedigree relationship of selection candidates,inbreeding in the GIFT pop-ulation has been effectively managed.After ten generations(10years),the maximum inbreeding level in this population by the2008spawning sea-son was low(only2.1%).The realized effective pop-ulation size was88(Ponzoni et al.2010).The current N e is acceptable in the short or medium term,but it should be increased to ensure contin-uing long-term responses to selection.To prevent the population from extinction or retain evolution-ary potential,the effective population size should be from150to500(Frankham2005).This is a chal-lenge because broodstock and rearing facilities will need to be increased5-to10-fold.This will be prob-lematic,particularly in countries where resources are limited.For species with long generation inter-vals,alternate year class breeding populations should be contemporaneously maintained to allow gene?ow between generations,hence increasing the effective population size and utilizing available facilities and personnel.With this design,there is a need to create good genetic linkages between year classes.This can be performed through repeated matings,that is the use of a certain proportion(10–30%)of parents previously used in alternate year classes.Through genetic connectedness among year classes and generations,the genetic trend for traits of interest can be estimated.

Estimation of genetic gain

Genetic evaluation should be conducted with each generation to monitor the progress of the selected population and to re?ne breeding technologies.In breeding programmes for carp,tilapia and giant freshwater prawns,genetic gains were calculated as the differences in the estimated breeding values between the progeny of the selection line in suc-cessive spawning seasons or by comparing the estimated breeding values of the selection line and control group within the same spawning season/ generation(Hung et al.2013b;Ninh et al.2013; Hamzah et al.2014b).In carp and tilapia,a sepa-rate control group was maintained in parallel with the selection line(Ninh et al.2013).For giant freshwater prawn,a control group was recreated each generation based on the population mean. The establishment of control populations is useful, but requires considerable funds and effort and may not be an option for commercial breeding companies.Alternatively,genetic gain may be esti-mated using mixed model procedures(Henderson 1975)that rely on the presence of genetic con-nectedness between generations,which in turn enables the estimation of genetic and environmen-tal trends over time.A similar approach is likely to be more realistic in the context of commercial production.

Cryopreservation of sperm from the base popula-tion is potentially a useful technique to measure genetic gain when resources permit and when the programme proceeds.This is mainly because the frozen sperm can present a wider genetic base than a random unselected control of limited size and eliminates any possibility of an accumulated genetic drift over time.Hence,the amount of genetic gain can be estimated with minimum bias relative to the maintenance of a separate control line.However,this approach does not accommo-date all changes as the maternal lines are always derived from the selected populations.Moreover, cryopreserved milt can be tactically used between year classes to reduce the risk of inbreeding in the selected population.In the future,once large-scale genetic evaluation is underway,cryopreserved sperm can be used to create genetic connectedness between populations.In addition,the establish-ment of a gene bank of cryopreserved milt would be useful for the conservation of genetic resources. On-farm testing of the improved strains will pro-vide the biological basis for the estimation of the impact of genetic improvement on commercial pro-duction.However,procedures for strain compari-sons require several steps,from determination of sample sizes associated with pre-de?ned statisti-cal power,implementation of the experiment, collection of data,statistical analysis and interpreta-tion of the results.When?nancial limitations are not a major issue,experiments should be rigorously designed and conducted to test performance of the improved strains developed from breeding pro-grammes in comparison with available stocks cul-tured by farmers or produced by other companies. Thus,the continued monitoring of genetic improve-ment programmes is essential in ensuring that the anticipated genetic gains are achieved.

Climate change

Although formal?sh breeding and genetic research programmes addressing climate change

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have not yet been initiated in Asian countries,a number of our studies have addressed this issue (Box3).One of the principle research areas is the effect of genotype by environment interactions to develop‘robust’strains,adapted to a wide range of different farming systems(see section genotype by environment interaction).The genetic basis of ?tness-related traits such as fecundity in GIFT tila-pia also re?ects the adaptive responses of the ani-mals to the cultured environment over several generations of selection for production perfor-mance(Hamzah et al.2014a).There are also genetic programmes to develop improved tilapia strains that can be grown in both freshwater and brackish water systems(Nguyen et al.2011b; Ninh et al.2014)or for rotational culture in shrimp farms(Pongthana et al.2010).Develop-ment of strains with resistance against common diseases such as Aeromonas hydrophila is reported for rohu carp(Sahoo et al.2011).Despite these initial successes,several areas of research in response to changing climatic and environmental conditions need systematic consideration in genetic improvement programmes.Understanding the quantitative genetic basis of adaptation and?t-ness-related traits of locally adapted strains(spe-cies)would help utilize them ef?ciently in breeding (cross-breeding)and culture systems as well as aid the exploration of possibilities for introgression of desirable genes from one to another species using genomic selection combined with reproductive technologies.Development of high-performing strains with good adaptation under harsh or stressed environments and the design of breeding strategies to reduce waste discharge into the envi-ronment will have bene?cial impacts on the future sustainability of aquaculture farming systems. Identi?cation of molecular mechanisms(e.g.geno-mic regions linked to improved performance under stress conditions)for?sh breeding and genome-wide selection will help improve dif?cult or expen-sive to measure traits such as adaptation,

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or behavioural characters.An examination of the genetic basis of physiological and social traits, such as cortisol level,which is an indicator of stress condition in?sh(Morm e de et al.2011),will provide basic information to develop animals that can increase environmental tolerance.In sum-mary,genetic research could contribute to develop effective responses to climate change issues to sus-tain future aquaculture systems.However,such research requires investment in physical resources and personnel,as well as long-term commitments from international organizations,national govern-ments and other stakeholders involved in the undertaking.

Gene(marker)-assisted and genomic selection

Despite the growth of molecular genetics,genomics and bioinformatics,there have been very limited applications to the genetic improvement of aqua-culture species in Asia.There are only a few instances of DNA markers being applied in selective breeding programmes(e.g.Ninh et al.2011),and the use of molecular genetics has mainly been for population characterization and biodiversity studies (Hallerman et al.2007).Although genetic linkage mapping has been developed for several aquacul-ture species and quantitative trait loci(QTL)have been identi?ed for various traits(Yue2013),there remains both technical and economic limitations for the application of gene-or marker-assisted selection(MAS)in selective breeding programmes. This is primarily due to limited marker availability, the small effect of markers with regard to QTLs, high genotyping costs,and computationally demanding marker-based breeding value estima-tion approaches.Furthermore,markers or QTLs detected in many experimental populations have often involved the crossing of genetically divergent lines which are not applicable to production popu-lations due to the inconsistency between markers and QTL across population associations,the inter-action of marker and QTL effects with genetic background and environment,and the overestima-tion of QTL effects(e.g.Dekkers2012).So far,only two applications of MAS in aquaculture have been reported:(i)infectious pancreatic necrosis(IPN)in Atlantic salmon and(ii)lymphocystis resistance in Japanese?ounder(Fuji et al.2007).Houston et al. (2010)and Moen et al.(2009)independently reported the same QTL on chromosome26that explained26and29%of the phenotypic variation in IPN resistance,respectively.These two cases are not representative of what is commonly found,as single QTLs are rarely found to explain such a large proportion of the variation in the traits of interest.With the rapid advancement and decreas-ing costs of high-throughput sequencing and DNA technologies,genomic selection,an advanced ver-sion of MAS based on estimated breeding values from a large number of markers across the gen-ome,has been rapidly adopted by dairy industries worldwide(Hayes et al.2009)and it is still under development in other livestock species such as beef cattle,sheep,poultry and pigs(Dekkers2012). Despite the potential bene?ts of genomic selection for traits which are dif?cult to measure(e.g.?esh quality or disease resistance),or traits with low heritability(e.g.deformity)in aquatic species with long generation times,many challenges remain when applying this approach to aquatic animal species due to a lack of pedigreed populations,phe-notypic records and industry structure.Another constraint is that SNP chips are not yet commer-cially available for the majority of aquatic animal species and have to be developed at substantial cost de novo.On the other hand,the aquaculture indus-try can take advantage of the fact that a majority of the theory,statistical methods and software packages for the design and implementation of genomic selection have been developed by animal and plant breeders(de los Campos et al.2013). Simulation studies have shown that genomic selec-tion in sib-based aquaculture breeding programmes can result in greater genetic gain(33–81%)and lower inbreeding(84%)than selection based on the conventional BLUP approach(Nielsen et al. 2009;Sonesson and Meuwissen2009).It is expected that in coming years,the availability of SNPs chips and high-throughput genotyping tech-nologies will no longer be a barrier,with subse-quent challenges more likely to be associated with the large-scale,routine collection of phenotypic data and the development of suitable database sys-tems to handle the vast amount of data which will be accumulated by breeding programmes.A com-mitment to long-term investment by stakeholders is also a necessity as regenotyping and resequenc-ing may be needed to maintain a high level of accuracy in breeding value estimation as well as broadening the breeding objectives when new traits are included.

In addition to genomic selection,application of technologies from the?eld of metagenomics has

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the potential to re?ne selective breeding technolo-gies for genetic improvement of disease resistance in aquaculture species.Recently,Ross et al. (2013)extended the genomic selection approach to determine the accuracy(predictive power)of metagenomic predictions of the status of in?am-matory bowel disease in humans and methane emission level in dairy cattle,using rumen?uid and faecal samples for massive parallel sequencing. While the correlation between metagenomic and phenotypic information achieved was reasonably high(0.4),it could be improved by increasing ref-erence population sizes and the number of pheno-types in combination with genomic predictions of the host DNA.The approach developed by Ross et al.(2013)was based on a standard mixed model methodology,with a metagenomic relation-ship matrix de?ned as matrices of n sample and m contig with elements being counts of the number of reads.Alternatively,the microbiotic community from animal tissues(gut,skin,faeces)may be con-sidered as a quantitative trait and microbial com-munities bene?cial for a particular character of interest encouraged by selection.Integration of multiple sources of‘omics’data(transcriptomics, proteomics and metabolomics)using a system biol-ogy approach(Kadarmideen2014)will also help unravel the biology of complex traits,gene regula-tory networks and their functions,as well as the biological pathways that contribute to variation in commercial traits of economic importance.

Dissemination of improved strains

Genetic improvement is not particularly useful unless the improved strains reach the end-users. One successful example is rohu carp in India where the improved line has been effectively dis-seminated to?sh producers through a systematic network of accredited public–private hatcheries(K. Mahapatra,personal communication).The hatch-eries specialize in the multiplication of the improved stock under strict protocols regarding effective population sizes and brood stock replace-ment to ensure that high-quality seed stock reaches both small farmers and commercial pro-ducers.In large countries or where the appropriate infrastructure is not developed,it may not be easy or cost-effective to transport seed or brood stock to remote areas after every generation of selection.In such cases,the hatcheries may receive brood stock less frequently and would need to conduct a more simpli?ed breeding scheme(e.g.cohort selection combined with rotational mating)to maintain the quality of brood stock.The cohort breeding pro-gramme has been successfully applied in freshwa-ter cray?sh,Cherax quadricarinatus(McPhee et al. 2004).This scheme is suitable for small commer-cial operations whose the main focus is on produc-tion and distribution of seedstock.It is simple and easily achieved by?eld technical staff.The cohort breeding scheme has been applied to maintain the quality of the GIFT strain in several commercial operations in Bangladesh,Costa Rica,Malaysia, Philippines,Thailand and Sri Lanka(N.H.Nguyen, unpublished results).

Furthermore,there are both techno-socioeco-nomic and legal aspects related to expansion sys-tems of genetic stocks such as brand name, trademark,genetic piracy,systems of accredited hatcheries and extension networking(Ponzoni et al.2012).In countries(e.g.India or Vietnam) where the above-mentioned breeding programmes are already underway,paying higher prices for improved seedstock is still not part of the culture. From our experience,the successful dissemination of improved strains depends more on sociology and economics rather than genetics.Guidance on the effective and responsible dissemination of genetically improved strains,both within and between countries,can be found in the FAO tech-nical manual(FAO2008).The risk assessment of improved strains in relation to genetic conserva-tion,resource management and biodiversity is dis-cussed at length by Lind et al.(2012).

Capacity to run genetic improvement programmes

While there is considerable aquaculture scienti?c expertise in Asia,this still needs to be comple-mented by the development of new skills in repro-duction biology,biotechnology,genetics,genomics and bioinformatics to support sustainable aquacul-ture development in the long term.One conse-quence of the limited availability of well-trained personnel in the areas of quantitative genetics and applied statistics to conduct well-designed breeding programmes for aquatic animal species is that there have been very few genetically improved strains of?sh or crustaceans developed and used for aquaculture in Asia.Broadening and improv-ing the research base and developing the capaci-ties of national aquaculture institutions through collaborations with international universities and

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organizations with a wide range of expertise from basic to applied sciences would lead to a better ser-vice for the aquaculture industry.In particular, formal training of higher degree students from Asian countries is essential to bring them to a point where they can become independent in developing and running genetic improvement pro-grammes for aquaculture species in the long term. There are many instances(Nguyen et al.2009), after the successful completion of their degrees, students have returned to their home country with a capacity to lead research programmes,and play an active role in training local staff,hatchery managers and farmers.Training at the hatchery and farm levels is critical as a means of supporting project development and achieving valuable out-comes from genetic research programmes.

Other issues

There are still many other challenges in the con-text of genetic improvement for farmed aquacul-ture species in Asia that are beyond the scope of this review.Examples of non-technical challenges include collaborations among research institutions, development of an aquatic genetic resource net-work,the exchange of genetic materials,and establishment of regional and national training centres.A concerted effort is also required to strengthen organizational arrangements,national policies and technical guidance in order to develop ef?cient support to key areas of the aquaculture sector.A well-organized national breeding struc-ture is needed to ensure the effective propagation of the improved strains and the distribution of high-quality seed to commercial production facili-ties.National partners must work closely with international collaborators to address challenging issues in aquaculture genetics and build capacity. Designing business models to sustain research outcomes beyond the life of individual genetic projects is particularly important as genetic improvement requires long-term effort and invest-ment.For instance,commercialization of breeding programmes would provide opportunities for venture capital and attract investors from other sectors,thereby generating revenue streams to fund ongoing genetic programmes.This would also confer opportunities for linking both public and private sectors and invite collaboration among government agencies,research institutions,indus-try partners and end-users.Revenue from levies on sales of selected stocks ideally should be direc-ted to the continued development of genetic lines for commercial production.Moreover,alternative mechanisms leading to self-funding to sustain genetic programmes should be planned prior to commencement of genetic projects.Development of web-based databases or user-friendly software packages to assist systematic data collection,stor-age,management,retrieval,archiving and secu-rity will be the key to the future success of genetic improvement programmes.Such avenues can also be used to provide practical solutions for problems arising from production and become indicators for future research directions and technology develop-ment.A database system must be accurate,consis-tent,?exible,economical and comprehensive to enable the incorporation of molecular genetic information(genes,DNA markers,SNP genotypes or genome sequence)as well as other new repro-ductive technologies(e.g.arti?cial insemination). Combined analysis of‘big’data from different ‘omics’disciplines poses several computational challenges that require investment in information technology infrastructure to support both distrib-uted data and processing.The legal framework and intellectual property issues for use and exchange of genetic data should be also considered according to national requirements and data pri-vacy standards.Although there is an increasing trend of investment by local governments in genetic improvement programmes,the advance-ment of infrastructure and facilities for aquacul-ture and rural development would foster the successful development and dissemination of supe-rior genetic lines to production for sustainable aquaculture in Asia.

Conclusions

Genetically improved strains are essential to aqua-culture development and have been shown by Yosef(2009)to be among the most important factors resulting in increased production,lower costs,increased consumption and,in some cases, improved overall nutritional status of certain sectors of the human population.The application of quantitative genetic theory to the improvement of farmed aquaculture species is still at an early stage,and its use should be expanded to develop important aquaculture species to further increase the productivity and quality of aquaculture prod-ucts.Potential species for genetic improvement in

18?2015John Wiley&Sons Ltd,F I S H and F I S H E R I E S Genetic selection in carp,tilapia and prawns N H Nguyen

Asia would be crustaceans(tiger prawn Penaeus monodon,Penaeidae and white leg shrimp Penaeus vannamei,Penaeidae)and?sh.Fish targets in Ban-gladesh,India and Sri Lanka include Catla(Catla catla,Cyprinidae);in the Philippines and Indone-sia,Milk?sh(Chanos chanos,Chanidae);in Malay-sia,Singapore and Thailand,Asian seabass(Lates calcarifer,Latidae);and in Vietnam,striped cat?sh (Pangasianodon hypophthalmus,Pangasiidae).There are also emerging species such as groupers(Epi-nephelus spp,Serranidae),cobia(Rachycentron can-adum,Rachycentridae),bivalve mollusc(oysters, abalone,scallops or clams)and even aquatic plants(seaweed)that may attract attention for genetic improvement.The successful achievements of new genetic programmes depend not only on systematic steps involved in the design and con-duct of experimental?eld work but also on the establishment of a base population with ample genetic variability to ensure a long-term response to selection.Choice of selection methods depends on species,objectives and the available resources of aquaculture enterprises.Ideally,a fully pedi-greed population should be maintained to enable the applications and utilizations of advanced statis-tical methods,such as best linear unbiased predic-tion(BLUP),for genetic evaluation and selection. Within-and between-family selection,based on an individual’s genetic merits and its relationship with other animals in the pedigree,shows several advantages over other methods(Nguyen and Ponzoni2006).In many cases,particularly in an Asian context,the design of genetic improvement programmes is frequently adjusted to?t the avail-ability of facilities and resources,rather than sta-tistical considerations.Instead,a systematically designed breeding programme should be estab-lished in the?rst place to enable the incorporation of potential new technologies such as molecular genetic(genomic)information and advanced reproduction techniques.Although commercial SNP chips are currently not available for many aquaculture species,this may not be a barrier in coming years due to the rapid advance in sequenc-ing technologies and diminishing costs of genome sequencing.Whole genome sequencing can theo-retically overcome limitations of SNP-based selec-tion by capturing complete linkage disequilibrium between markers and causative variants,ulti-mately offering unprecedented opportunities in the estimation of breeding values directly from genome sequence data and thus enabling sequence-based selection for aquatic farmed animal species in the foreseeable future.

Acknowledgements

I am thankful for the opportunity to work and col-laborate with national aquaculture research insti-tutions in Asia and Africa,namely the Freshwater Fisheries Research Centre of the Chinese Academy of Fisheries Science;Bangladesh Fisheries Research Institutes(BFRI),Central Institute for Freshwater Research,India(CIFA);Department of Fisheries, Malaysia;NAQDA,Ministry of Fisheries Aquatic Resources,Sri Lanka;Department of Fisheries, Thailand;Research Institutes for Aquaculture (RIA1&2),Vietnam;Regional Research Centre for Africa and West Africa,Egypt;Water Research Institute,Ghana and the National Aquaculture Centre,Malawi.I also extend my thanks to Dr Raul Ponzoni(formerly from the WorldFish Cen-tre).Prof Richard Burns,Associate Prof Wayne Knibb and Dr Robert Lamont at the University of the Sunshine Coast kindly helped review the draft manuscript.Insightful suggestions from the jour-nal editor,Prof Gary Carvalho and anonymous reviewers also helped strengthen the manuscript.

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20?2015John Wiley&Sons Ltd,F I S H and F I S H E R I E S Genetic selection in carp,tilapia and prawns N H Nguyen

高中化学选修5常见有机反应的十大类型

常见有机反应的十大类型 1. 取代反应 有机物分子里的某些原子或原子团被其他原子或原子团所代替的反应。（1）卤代： （2）硝化： （3）磺化： （4）卤代烃水解： （5）酯水解： （6）羟基（）取代： （7）分子间脱水：

2. 加成反应 有机物分子中双键（或三键）两端的碳原子与其他原子或原子团直接结合生成新的化合物的反应。 （1）碳碳双键的加成： （2）碳碳三键的加成： （3）醛基的加成： （4）苯环的加成： 3. 加成聚合（加聚）反应 相对分子质量小的不饱和化合物聚合成相对分子质量大的高分子化合物的反应。 （1）丙烯加聚： （2）二烯烃加聚：

4. 缩合聚合（缩聚）反应 单体间相互反应而生成高分子化合物，同时还生成小分子（如水、氨、氯化氢等）的反应（又叫逐步聚合反应）。 （1）制酚醛树脂： （2）缩聚制酯： （3）氨基酸缩聚： 5. 消去反应 有机化合物在一定条件下，从一个分子中脱去一个小分子（如水、卤化氢等）而生成不饱和（含双键或三键）化合物的反应。 6. 氧化还原反应 在有机化学中，通常把有机物得氧或去氢的反应称为氧化反应；反之，加氢或去氧的反应称为还原反应。 （1）氧化反应：

（2）还原反应： 7. 酯化反应（亦是取代反应） 酸和醇起作用，生成酯和水的反应 8. 水解反应（亦是取代反应，其中卤代烃、酯的水解见取代反应部分） 化合物和水反应生成两种或多种物质的反应（有卤代烃、酯、酰胺、糖等）。 麦芽糖葡萄糖 9. 脱水反应（又叫碳化） 有机物分子脱去相当于水的组成的反应。

10. 裂化反应 在一定条件下，把相对分子质量大、沸点高的长链烃，断裂为相对分子质量小、沸点低的短链烃的反应。 (责任编辑：化学自习室)

药物合成反应重要人名反应

1.Hunsdriecke反应：羧酸银盐和溴或碘反应，脱去二氧化碳，生成比原反应物少一个碳原子的卤代烃。 2.Sandmeyer反应：用氯化亚铜或溴化亚铜在相应的氢卤酸存在下，将芳香重氮盐转化成卤代芳烃。 3.Gattermann反应：将上面改为铜粉和氢卤酸。 4.Shiemann反应：将芳香重氮盐转化成不溶性的重氮氟硼酸盐或氟磷酸盐，或芳胺直接用亚硝酸纳和氟硼酸进行重氮化，此重氮盐再经热分解（有时在氟化钠或铜盐存在下加热），就可以制得较好收率的氟代芳烃。 5.Williamson合成：醇在碱（钠，氢氧化钠，氢氧化钾）存在下与卤代烃反应生成醚。 6.Gabriel合成：将氨先制备成邻苯二甲酰亚胺，利用氮上氢的酸性，先与氢氧化钾生成钾盐，然后与卤代烃作用，得N-烃基邻苯二甲酰亚胺，肼解或酸水解即可得纯伯胺。 7.Delepine反应：用卤代烃与环六亚甲基四胺（乌洛托品）反应得季铵盐，然后水解可得伯胺。 8.Leuckart反应：用甲酸及其铵盐可以对醛酮进行还原烃化，得各类胺。 9.Ullmann反应：卤代芳烃与芳香伯胺在铜或碘化铜及碳酸钾存在并加热的条件下可得二苯胺及其同系物。

10.Friedel-Crafts反应：在三氯化铝催化下，卤代烃及酰卤与芳香族化合物反应，再环上引入烃基及酰基。 11.Meerwein芳基化反应：芳基自由基可与烯反应，引致烯键的碳原子上。 12.Gomberg-Bachmann反应：芳香自由基与过量存在的另一芳香族化合物发生取代反应，得到联苯。 方向自由基的来源主要有三种：最常用重氮离子的分解;其次为N-亚硝基乙酰苯胺类及芳酰过氧化物的分解 13.Hoesch反应：腈类化合物与氯化氢在Lewis酸催化剂ZnCl2的存在下与具有烃基或烷氧基的芳烃进行反应可生成相应的酮亚胺，在经水解则得具有羟基或烷氧基的芳香酮。 14.Gattermann反应：将具有羟基或烷氧基的芳烃在三氯化铝或氯化锌催化下与氰化氢及氯化氢作用生成相应芳香醛的反应。 15.Vilsmeier-Haack反应：以N-取代的甲酰胺化试剂在氧氯化磷作用下，在芳核或杂环上引入甲酰基。 16.Rimer-Tiemann反应：将酚及某些杂环化合物与碱金属的氢氧化物溶液和过量的氯仿一起加热形成芳醛的反应。 17.Claisen反应和Dieckmann反应：羧酸酯与另一分子具有α-活泼氢的酯进行缩合的反映称为Claisen缩合。若两个酯在同一分子之内，在上述条件下可发生分子内缩合，得环状β-酮酸酯，此反应称为Dieckmann反应。

有机反应的主要类型

有机反应的主要类型、有机物的制备一、基础梳理

2 、烃的衍生物的相互转化中有机反应类型之间的关系 （1）相互取代关系：如 R －X R －OH : （2）加成消去关系：如 烯烃 卤代烃 （3）氧化还原关系：如 －CH 2OH －CHO （4）结合重组关系：如 RCOOH ＋R －OH RCOOR ＋H 2O 二、考点俐析 考点1：有机反应类型： 例1、茉莉醛具有浓郁的茉莉花香，其结构简式如下所示： 关于茉莉醛的下列叙述错误的是（ ） A 在加热和催化剂作用下，能被氢气还原 B 能被高锰酸钾酸性溶液氧化 C 在一定条件下能与溴发生取代反应 D 不能与氢溴酸发生加成反应 2.下列有机反应中，不属于取代反应的是：( ) . 3．氧氟沙星是常用抗菌药，其结构简式如图所示，下列对氧氟沙星叙述错误．． 的是( ) N O O N OH O N CH 3F H 3C A.能发生加成、取代反应 B.能发生还原、酯化反应 C.分子内共有19个氢原子 D.分子内共平面的碳原子多于6个 三、练习巩固 1．烯烃与CO 、H 2在催化剂作用下生成醛的反应叫烯烃的醛化反应．乙烯的醛化反应为：CH 2=CH 2+CO+H 2→CH 3CH 2CHO ，由C 4H 8的烯烃进行醛化反应，得到醛的同分异构体的数目应为 A ．2种 B ．3种 C ．4种 D ．5种 2．L —多巴是一种有机物，可用于帕金森综合症的治疗，其结构简式如下： 下列关于L —多巴的叙述中不正确．．．的是 A ．长期暴露在空气中易变质 】

B．既有酸性，又有碱性 C．一定条件下能发生聚合反应 D．分子中只有6个碳原子共平面 3．下列有机物在一定条件下反应，所生成的有机物的种类由多到少的顺序是（） ①甲醇和乙醇的混合物与浓硫酸加热生成醚②乙二醇与乙酸酯化反应③氨基乙酸和丙氨酸生成二肽④苯酚和浓溴水反应 A．④③②①B．①②③④C．③①②④D．③②④① 4. 下列5个有机化合物中,能够发生酯化、加成和氧化3种反应的是（） ① CH2===CHCOOH ② CH2===CHCOOCH3 ③ CH2===CHCH2OH ④ CH3CH2CH2OH ⑤ CH2CH(OH)CH2CHO A. ①③④ B.②④⑤ C. ①③⑤ D. ①②⑤ 5．拟除虫菊酯是一类高效、低毒、对昆虫具 ) 有强烈触杀作用的杀虫剂，其中对光稳定的 溴氰菊醋的结构简式如右图： 下列对该化合物叙述正确的是（） A 属于芳香烃 B 属于卤代烃 C 在酸性条件下不水解 D 在一定条件下可以发生加成反应 6、将用于2008年北京奥运会的国家游泳中心(水立方)的建筑采用了膜材料ETFE，该材料 为四氟乙烯与乙烯的共聚物，四氟乙烯也可与六氟丙烯共聚成聚全氟乙丙烯。下列说法错误 ．．的是（） A．ETFE分子中可能存在“—CH2—CH2—CF2—CF2—”的连接方式 B．合成ETFE及合成聚全氟乙丙烯的反应均为加聚反应 C．聚全氟乙丙烯分子的结构简式可能为CF2CF2CF2CF2CF2n D．四氟乙烯分子中既含有极性键又含有非极性键 7．有七种物质：①甲烷、②苯、③聚乙烯、④聚异戊二烯、⑤2-丁炔、⑥环己烷、⑦环已烯，既能使酸性高锰酸钾溶液褪色．又能使溴水因反应而褪色的是 （） （ A．③④⑤ B．④⑤ C．④⑤⑦ D.③④⑤⑦ 8．某有机物的结构简式为CH 2 CHO CH 2 COOH CH 2 CH 2 OH ，它在一定条件下可能发生的反应是（） ①加成；②水解；③酯化；④氧化；⑤中和；⑥消去；⑦还原A．①③④⑤⑥⑦B．①③④⑤⑦C．①③⑤⑥⑦D．②③④⑤⑥

药物合成反应习题集

《药物合成技术》 习题集 适用于制药技术类专业 第一章概论 一、本课程的学习内容和任务是什么？学好本课程对从事药物及其中间体合成工作有何意义？ 二、药物合成反应有哪些特点？应如何学习和掌握？ 三、什么是化学、区域选择性？举例说明。 四、什么是导向基？具体包括哪些类型？举例说明。 五、药物合成反应有哪些分类方法？所用试剂有哪些分类方法？举例说明。 六、查资料写一篇500字左右的短文，报道药物合成领域的新技术及发展动态？ 第二章卤化技术（Halogenation Reaction） 一、简答下列问题 1．何为卤化反应？按反应类型分类，卤化反应可分为哪几种？并举例说明。 2．在药物合成中，为什么常用卤化物作为药物合成的中间体？ 3.在较高温度或自由基引发剂存在下，于非极性溶剂中，Br 2 和NBS都可用于烯丙位和苄位的溴取代，试比较它们各自的优缺点。 4.比较X 2 、HX、HOX对双键离子型加成的机理、产物有何异同，为什么？ 5.解释卤化氢与烯烃加成反应中，产生马氏规则的原因（用反应机理）。为什么Lewis酸能够催化该反应？ 6．解释溴化氢与烯烃加成反应中，产生过氧化效应的原因？ 7．在羟基卤置换反应中，卤化剂（HX、SOCl 2、PCl 3 、PCl 5 ）各有何特点，它们的 使用范围如何？ 二、完成下列反应 三、为下列反应选择合适的试剂和条件，并说明原因。 四、分析讨论 1．试预测下列各烯烃溴化（Br 2/CCl 4 ）的活性顺序。

2．在乙胺嘧啶中间体对氯氯苄的制备中，有如下两条路线，各有何特点？试讨论其优缺点。 3．以下是三种制备溴乙烷的方法，其中哪种适合工业生产，哪种适合实验室制备？ 4．在氯霉素生产过程中，对-硝基-α-溴代苯乙酮的制备时， （1）反应有无催化剂？若有，属于哪种催化剂？ （2）将对硝基苯乙酮与溶于氯苯中,加热至24-25℃，滴加少量溴，当有HBr生成并使反应液变色则可继续加溴，否则需升温至50℃直至反应开始方可继续滴加溴，为什么？ （3）反应毕开大真空排净溴化氢，反应过程中溴化氢也不断移走，是不是移得越净越有利于反应？为什么？ （4）生产过程中，影响因素有哪些？ 第三章烷基化技术 (Hydrocarbylation Reaction ,Alkylation) 一、解释概念及简答 1．常用的烃化剂有哪些？进行甲基化及乙基化时，应选择哪些烃化剂？引入较大烃基时应选用哪些烃化剂？ 2．什么叫相转移催化反应？其原理是什么？采用相转移催化技术有什么优点？ 3．利用Gabriel反应与Delepine反应制备伯胺时，有什么相同与不同点？ 4．什么是羟乙基化反应？在药物合成中有什么特别的意义？ 5．进行F-C烃化反应时，芳香族化合物结构、卤代烃对反应有何影响？常用哪些催化剂？如何选择合适的催化剂。 6．若在活性亚甲基上引入两个烃基，应如何选择原料和操作方法？并解释原因。 二、利用Williamson法制混合醚时，应合理选择起始原料及烃化试剂，试设计下列产品的合成方法，并说明原因，掌握其中的规律。 三、完成下列反应 四、为下列反应选择适当的原料、试剂和条件，并说明依据。 五、利用所给的原料，综合所学知识合成下列产品 1．以甲苯、环氧乙烷、二乙胺为主要原料，选择适当的试剂和条件合成局麻药盐酸普鲁卡因。 2．以乙苯为主要原料，选择适当的试剂和条件合成氯霉素中间体对硝基-α-胺基

常见加聚反应的类型有：

常见加聚反应的类型有： 同一种单体加聚，该单体一般是单烯烃或共轭二烯烃。 由不同单体加聚，单体一般为烯烃。 常见缩聚反应的类型有： 酚醛缩聚。 氨基酸缩聚。 羟基＋羧基。 由高聚物找单体，一般将高聚物主链上的碳原子以偶数个断裂；若按此断裂写不出单体，一般此高聚物为缩聚反应得到的高聚物，要补充消去的小分子物质。 【例1】 A 、 B 、 C 、 D 、 E 、 F 、 G 、 H 、 I 、 J 均为有机化合物。根据以下框图，回答问题： ⑴B 和C 均为有支链的有机化合物，B 的结构简式为______； C 在浓硫酸作用下加热反应只能生成一种烯烃 D ， D 的结构简式为______________________________； ⑵G 能发生银镜反应，也能使溴的四氯化碳溶液褪色，则G 的结构简式为____________________________； ⑶⑤的化学方程式是_______________________________； ⑨的化学方程式是_________________________________； ⑷①的反应类型是__________________， ④的反应类型是__________________， ⑦的反应类型是__________________； ⑸与H 具有相同官能团的H 的同分异构体的结构简式为__________________________________________。 【例2】 PCT 是一种新型聚酯材料，下图是某研究小组合成PCT 的路线。

请回答下列问题： ⑴由A生成D的化学方程式为________； ⑵由B生成C的反应类型是________________，C的化学名称为______________； ⑶由E生成F的化学方程式为____________,该反应的类型为__________________； ⑷D的同分异构体中为单取代芳香化合物的有____________(写结构简式) ⑸B的同分异构体中，能发生水解反应，且苯环上一氯代产物只有一种的是________(写结构简式)。 【例3】(2011上海28) 异丙苯()是一种重要的有机化工原料。 根据题意完成下列填空： ⑴由苯与2-丙醇反应制备异丙苯属于_______________反应；由异丙苯制备对溴异丙苯的反应试剂和反应 条件为_______________________________。 ⑵异丙苯有多种同分异构体，其中一溴代物最少的芳香烃的名称是______________________。 ⑶α–甲基苯乙烯()是生产耐热型ABS 树脂的一种单体，工业上由异丙苯催化脱氢得到，写出由异丙苯制取该单体的另一种方法(用化学反应方程式表示)。 ⑷耐热型ABS树脂由丙烯腈(CH2＝CHCN)、1，3–丁二烯和α–甲基苯乙烯共聚生成，写出该树脂的结构 简式__________(不考虑单体比例)。

有机化学十种反应类型详细小结精美版

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常见有机反应的十大类型 李勇 1. 取代反应 有机物分子里的某些原子或原子团被其他原子或原子团所代替的反应。（1）卤代： s （2）硝化： s （3）磺化： （4）卤代烃水解： （5）酯水解：

（6）羟基（ OH）取代： （7）分子间脱水： 2. 加成反应 有机物分子中双键（或三键）两端的碳原子与其他原子或原子团直接结合生成新的化合物的反应。 （1）碳碳双键的加成： （2）碳碳三键的加成： （3）醛基的加成： （4）苯环的加成： 3. 加成聚合（加聚）反应 相对分子质量小的不饱和化合物聚合成相对分子质量大的高分子化合物的反应。

（1）丙烯加聚： （2）二烯烃加聚： 4. 缩合聚合（缩聚）反应 单体间相互反应而生成高分子化合物，同时还生成小分子（如水、氨、氯化氢等）的反应（又叫逐步聚合反应）。 （1）制酚醛树脂： （2）缩聚制酯： （3）氨基酸缩聚： 5. 消去反应 有机化合物在一定条件下，从一个分子中脱去一个小分子（如水、卤化氢等）而生成不饱和（含双键或三键）化合物的反应。

6. 氧化还原反应 在有机化学中，通常把有机物得氧或去氢的反应称为氧化反应；反之，加氢或去氧的反应称为还原反应。 （1）氧化反应： （2）还原反应： 7. 酯化反应（亦是取代反应） 酸和醇起作用，生成酯和水的反应 s 8. 水解反应（亦是取代反应，其中卤代烃、酯的水解见取代反应部分）

化合物和水反应生成两种或多种物质的反应（有卤代烃、酯、酰胺、糖等）。 麦芽糖葡萄糖 9. 脱水反应（又叫碳化） 有机物分子脱去相当于水的组成的反应。 10. 裂化反应 在一定条件下，把相对分子质量大、沸点高的长链烃，断裂为相对分子质量小、沸点低的短链烃的反应。

缩合反应的定义及分类方法(精)

第七章 缩合 第一节 概述 一、缩合反应的定义及分类方法 1． 定义： ★凡两个或多个有机化合物分子通过反应释出小分子而形成一个新的较大分子的反应；或同一个分子发生分子内的反应形成新分子都可称为缩合反应。释出的简单分子可以是水、醇、卤化氢、氨等。也有些是加成缩合，不脱去任何小分子。 2． 分类： 就化学键的形成而言，缩合反应包括碳－碳键和碳－杂键的形成反应。 二、缩合反应的重要性 缩合反应是形成分子骨架的重要反应类型之一。广泛地用于生产香料、医药、农药、染料等化工产品中。如重要有机中间体乙酰乙酸乙酯的合成： EtoNa H + CH 32H 5 CH 3CCH 22H 5C 2H 5OH O O O 1)2)+2 镇静催眠药物中间体2－甲基－2－戊烯醛的合成： CH 3CH 2CHO 3 CH 3CH 2CH=C-CHO 240℃，15min (89%) 第二节 羟醛缩合 ★醛或酮在一定条件下可发生缩合反应。缩合反应分两种情况：一种是相同的醛或酮分子 间的缩合，称为自身缩合；另一种是不同的醛或酮分子间的缩合，称为交叉缩合。 ★一、羟醛缩合 H 3 C H O C H 3C H OH C H 2 C O H C H 3C H H C O H C 提供羰基 提供活泼α－H β－羟基醛 α、β－不饱和醛 含有活泼α－H 的醛或酮在碱或酸催化作用下经亲核加成反应先生成β－羟基醛（酮），再脱水发生消除反应便成α、β－不饱和醛或酮。该类型的反应称为羟醛缩合反应。 它包括醛醛缩合、酮酮缩合和醛酮交叉缩合三种反应类型。 1．醛醛缩合反应 醛醛缩合反应可分为醛的自身缩合和不同醛间的交叉缩合反应两类。醛醛缩合后可得到

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一. 教学内容： 专题一重要有机化学反应类型 1. 取代反应 ①定义：有机分子里的某些原子或原子团被其它原子或原子团所代替的反应叫取代反应。 ②能发生取代反应的物质：、苯、、苯酚、甲苯 ③典型反应 2. 加成反应 ①定义：有机分子里不饱和的碳原子跟其它原子或原子团直接结合生成别的物质。加成反应是不饱和键（主要为，）重要性质。 ②能发生加成反应的物质有：烯烃、炔烃、苯环、醛、酮、油脂等。 ③典型反应 （水溶液）（溴水褪色） （制取塑料用） （1，2加成） （1，4加成） （工业制乙醇） 3. 加聚反应 ①本质：通过自身加成反应形成高分子化合物。 特征：生成物只有高分子化合物，且其组成与单体相同，如聚乙烯与乙烯的比相同。 ②能发生加聚反应的物质有：乙烯、丙烯、1，3—丁二烯、异戊二烯、氯乙烯等。 ③典型反应

塑料 天然橡胶 4. 缩聚反应 ①定义：单体间通过缩合反应而生成高分子化合物，同时还生成小分子（如水、氨等） 的反应。 ②特征：有小分子生成，所以高分子化合物的组成与单体不同。 ③能发生缩聚反应的物质：苯酚与甲醛；葡萄糖，氨基酸，乙二醇与乙二酸等。 ④典型反应 （的确良） 5. 消去反应 ①定义：从一个有机分子中脱去一个小分子（如水、卤化氢等分子），而生成不饱和 （双键或叁键）化合物的反应。 ②能发生消去反应的物质：某些醇和卤代烃。 ③典型反应 6. 脱水反应

①本质与类型：脱水反应是含羟基的化合物非常可能具有的性质，通常是两个羟基之间可脱去一分子水，也可以是一个羟基与另一个非羟基氢结合脱去一分子水。脱水可以在一个分子内进行，也可在分子之间进行。 ②能脱水的物质有：醇、羧酸、蔗糖、氨基酸、无机含氧酸等。 ③典型反应 （乙酸酐） （）（） （） （三磷酸）

药物合成反应实验讲义

药物合成反应实验讲义 编写教师：王曼张云凤

目录 实验1 苯妥英钠（Phenytoin Sodium）的合成 (1) 一、目的要求 (1) 二、实验原理 (1) 三、仪器与试剂 (2) 四、实验步骤 (3) 五、结构确证 (3) 思考题： (4) 实验2 尼群地平的合成 (5) 一、实验目的 (5) 二、方案提示 (5) 三、要求 (5) 实验3 阿昔洛韦的合成研究 (6) 一、目的 (6) 二、要求 (6)

实验1 苯妥英钠（Phenytoin Sodium）的合成 （综合性实验11学时） 一、目的要求 1. 学习安息香缩合反应的原理和应用氰化钠及维生素B1为催化剂进行反应的实验方法。 2. 了解剧毒药氰化钠的使用规则。 二、实验原理 苯妥英钠为抗癫痫药，适于治疗癫痫大发作，也可用于三叉神经痛，及某些类型的心律不齐。苯妥英钠化学名为5，5-二苯基乙内酰脲，化学结构式为： H N N ONa O 苯妥英钠为白色粉末，无臭、味苦。微有吸湿性，易溶于水，能溶于乙醇，几乎不溶于乙醚和氯仿。 合成路线如下： CHO 催化剂C CH O [O]C C O O C C O O +C O NH2 NH2 NaOH H N N ONa O 2

三、仪器与试剂 1、主要仪器 磁力搅拌器、温度计、球形冷凝管、三口烧瓶、水浴锅、真空泵、布氏漏斗、抽滤瓶、圆底烧瓶、滴管、量筒、烧杯、玻璃棒、小漏斗等。 2、试剂 名称规格用量 苯甲醛 C.P. 7.5ml NaOH 2mol/L 7.5ml 乙醇 C.P. 20ml VB1 C.P. 2.7g NaOH C.P. 适量 硝酸65％—68％25ml NaOH 15％25ml 醋酸钠 C.P. 1g 尿素 C.P. 3g 乙醇95％40ml 活性炭工业少量95％乙醇-乙醚混合液1:1 少量

《药物合成反应(闻韧主编第三版)》人名反应整理

《药物合成反应（闻韧主编第三版）》人名反应整理 一、卤化反应 1、Hunsdriecke反应（汉斯狄克反应）：羧酸银盐和溴或碘反应，脱去二氧化碳，生成比原反应物少一个碳原子的卤代烃。 2、Sandmeyer反应（桑德迈尔反应）：用氯化亚铜或溴化亚铜在相应的氢卤酸存在下，将芳香重氮盐转化成卤代芳烃。 3、Gattermann反应（加特曼反应）：将Sandmeyer反应条件改为铜粉和氢卤酸。 4、Schiemann反应（席曼反应）：将芳香重氮盐转化成不溶性的重氮氟硼酸盐或氟磷酸盐，或将芳胺直接用亚硝酸钠和氟硼酸进行重氮化，此重氦盐再经热分解(有时在氟化钠或铜盐存在下加热)，就可以制得较好收率的氟代芳烃。 二、烃化反应 5、Willamson合成（威廉姆森合成）：醇在碱(钠，氢氧化钠，氢氧化钾等) 存在下与卤代烃反应生成醚的反应。 6、Gabriel合成（盖布瑞尔合成）：将氨先制备成邻苯二甲酰亚胺，利用氮上氢的酸性，先与氢氧化钾形成钾盐，然后与卤代烃作用，得N-烃基邻苯二甲酰亚胺，肼解或酸水解即可得纯伯胺。 7、Delepine反应（德勒频反应）：用卤代烃与环六亚甲基四胺(乌洛托品Methenamine)反应得季铵盐，然后水解可得伯胺。 8、Leuckart-Wallach反应（鲁卡特-瓦拉赫反应）：用甲酸及其铵盐可以对醛酮进行还原烃化，得各类胺。 9、Ullmann反应（沃尔曼反应）：卤代芳烃与芳香伯胺在铜或碘化铜及碳酸钾存在并加热的条件下可得二苯胺及其同系物。 三、酰化反应 10、Friedel-Crafts反应（傅列德尔-克拉夫茨反应，也称傅-克酰基化反应）：羧酸及羧酸衍生物在质子酸或Lewis酸的催化下，对芳烃进行亲电取代生成芳酮的反应。 11、Hoesch反应（赫施）：腈类化合物与氯化氢在Lewis 酸催化剂ZnCl2的存在下与烃基或烷氧基取代的芳烃进行反应可生成相应的酮亚胺，再经水解则羟基或烷氧基取代的芳香酮。 12、Gattemann反应（伽特曼反应）：将羟基或烷氧基取代的芳烃在AlCl3、ZnCl2催化下与氰化氢及氯化氢反应生成牙胺盐酸盐，再经水解生成相应芳香醛的反应。 13、Vilsmeier-Haack反应（维斯迈尔-哈克反应）：以N-取代的甲酰胺为甲酰化试剂，在氧氯化磷的催化下，在芳核（杂）环上引入甲酰基。 14、Rimer-Tiemann反应（瑞穆尔-悌曼反应）：苯酚和氯仿在强碱性水溶液中加热，生成芳醛的反应。 15、Claisen反应和Dieckmann反应（克莱森反应和狄克曼反应）：羧酸酯与另一分子具有α-活泼氢的酯进行缩合得到β-酮酸酯的反应称为Claisen反应，也成为克莱森缩合。若两个酯在同一分子之内，在上述条件下可发生分子内缩合，得环状β-酮酸酯，此反应称为Dieckmann 反应。 四、缩合反应 16、Aldol缩合（艾德尔缩合）：含有α-活泼氢的醛或酮，在碱或酸的催化下发生自身缩合，或与另一分子的醛或酮发生缩合，生成β-羟基醛或酮类化合物的反应，该类化合物不稳定易发生消除反应生成α，β-不饱和醛酮。 17、Chaisen-Schimidt反应（克莱森-史密斯特反应）：芳醛和脂肪族、酮在碱催化下缩合生成β-不饱和醛、酮的反应。 18、Tollens缩合（托伦斯缩合）：甲醛在碱的催化下，可与含有α-活泼氢的醛、酮进行醛醇

常见的有机物反应类型知识点整理与合成速成训练

常见的有机物反应类型知识点整理与合成速成训练

4、常见合成技巧 有机合成题有多种多样，有机合成的方法也很多。因此，掌握一定的合成技巧是必需的。 ㈠基团的引入与消去 ⑴羟基的引入 ①卤代烃取代法 ②烯烃水解法 ③醛还原法 ④烷烃催化氧化法 ⑤酯水解法 ⑥酚钠酸化法 ⑵羟基的消去 ①脱水法 ②氧化法 ③酯化法 ④取代法 ⑤中和法 ㈡成环与断环 ⑴成环 炔 OHCCHO HOOCCOOH CH 2 n 高聚物 CH ≡CH 苯 3CH 2OCH 2CH 醚 酚 CH 2

①加成法 ②酯化法 ③消去法 ④氧化法 ⑵开环 ㈢官能团的移动 ⑴羟基的移动 RCH 2CH 2OH H 2O+RCH=CH 2 H 2O+RCH=CH 2 RCH 2CH 2OH ⑵双键的移动 RCH 2CH=CH 2+HBr RCH 2CH 2BrCH 3 RCH 2CH 2BrCH 3+NaOH RCH=CHCH 3+NaBr+H 2O 5、举例 ⑴捕捉信息进行迁移转化 例如：醛是一类活泼的有机物，有α—H 的醛(与—CHO 直接相连的C 上的H 原子叫α—H)在有碱存在的条件下，能发生羟醛缩合反应。如： CH 3CHO+H —CH 2CHO CH 3C(OH)CH 2CHO 无α—H 的醛在有浓碱存在的条件下，能发生自身氧化还原反应。如：HCOONa+CH 3OH 根据以上信息及已学的知识，请以甲苯、乙烯为原料(其它无机原料任选) ⑵掌握逆向合成法的思维程序 例：用丙烯制取甘油，请写出各步合成的方程式。 参考答案与思路分析 1、 NaOH 醇 一定条件下 浓硫酸 △

常见的缩合反应类型

缩合反应 condensation (reaction) 两个或多个有机分子相互作用后以共价键结合成一个大分子，同时失去水或其他比较简单的无机或有机小分子的反应。其中的小分子物质通常是水、氯化氢、甲醇或乙酸等。缩合反应可以是分子间的，也可以是分子内的。 在多官能团化合物的分子内部发生的类似反应则称为分子内缩合反应。 缩合反应可以通过取代、加成、消除等反应途径来完成。 多数缩合反应是在缩合剂的催化作用下进行的，常用的缩合剂是碱、醇钠、无机酸等。 缩合作用是非常重要的一类有机反应，在有机合成中应用很广，是由较小分子合成较大分子有机化合物的重要方法。 有时两个有机化合物分子互相作用成一个较大的分子而并不放出简单分子，也称缩合。 常用于氨基酸合成 常见的缩合反应类型 ①羟醛缩合反应 为醛、酮或羧酸衍生物等羰基化合物在羰基旁形成新的碳-碳键，从而把两个分子结合起来的反应。这些反应通常在酸或碱的催化作用下进行。一个羰基化合物在反应中生成烯醇或烯醇负离子后进攻另一个羰基的碳原子，从而生成新的碳-碳键。最简单的例子是乙醛的羟醛缩合反应： ②克莱森缩合反应

含有α-活泼氢的酯类在醇钠、三苯甲基钠等碱性试剂的作用下，发生缩合反应形成β-酮酸酯类化合物，称为克莱森缩合反应，反应可在不同的酯之间进行，称为交叉酯缩合；也可将本反应用于二元羧酸酯的分子内环化反应，这时反应又称为迪克曼反应(Dieckmann reaction)。例如，乙酸乙酯在乙醇钠作用下生成乙酰乙酸乙酯： ③苯偶姻缩合反应 芳香族醛在氰化钾作用下发生两分子缩合，生成苯偶姻类化合物： ④偶姻缩合反应 羧酸酯与钠发生双分子还原，生成偶姻类化合物。如以适当的链状二元羧酸酯为原料，通过这个反应，使发生分子内偶姻缩合，能制得中环化合物： ⑤曼尼希反应 醛或酮与甲醛和二级胺或一级胺在弱酸性条件下发生氨甲基化反应。应用这个反应可在很温和的条件下合成一些复杂的、原仅天然存在的有机含氮化合物。例如，用等摩尔的丁二醛、3-戊酮二酸和甲胺的稀溶液，在35℃、pH＝5的条件下缩合，生成托品酮： ⑥维蒂希反应 醛或酮与维蒂希试剂发生缩合，是合成烯烃的重要方法。 ⑦乌尔曼缩合反应 卤代芳烃在铜粉(或氯化亚铜、氧化铜、硫酸铜、醋酸铜等)存在下与芳胺反应，生成高一级芳胺。当卤代芳烃有吸电子基团和芳胺有给电子基团，则有利于反应进行。除芳胺外，其他的亲核试剂如酚、硫酚等也能参与本反应。可利用本法由芳胺制备高一级的芳胺。

药物合成反应复习资料汇总

第一章绪论 1、药物合成反应中反应类型有哪些？ ①按有机分子的结构变换方式分：新基团的导入反应；取代基的转化反应；有机分子的骨架。 ②按反应机制分：极性反应（a.亲核试剂、b.亲电试剂）；自由基反应；协同反应 2、药物合成反应主要研究对象：化学合成药物 3、化学品的安全使用说明书——MSDS 4、原子经济性反应：“原子经济性”是指在化学品合成过程中，合成方法和工艺被设计成能把反应过程中使用的所有原料尽可能多的转化到最终产物中。 5、三废：废气、废水、废渣 第二章硝化反应 1、混酸硝化试剂的特点有哪些？ ①硝化能力强；②氧化性较纯硝酸小；③对设备的腐蚀性小 2、硝化试剂的活泼中间离子为：硝酰正离子NO2○+ 3、桑德迈尔反应定义及应用 定义:在氯化亚铜或溴化铜的存在下，重氮基被氮或溴置换的反应;重氮基被氰基置换：将重氮盐与氰化亚铜的配合物在水介质中作用，可以使重氮基被氰基置换，该反应也称Sandmeyer反应。 应用：CuX+Ar-N2X Ar-X+N2 (X:Cl,Br,-CN) 4、常用的重氮化试剂 一般是由盐酸、硫酸、过氯酸和氟硼酸等无机酸与亚硝酸钠作用产生。 5、硝化反应定义：指向有机分子结构中引入硝基（—NO2）的反应过程，广义的硝化反应包括生产（C—NO2、N—NO2和O—NO2）反应。 6、重氮化反应定义：含有伯氨基的有机化合物在无机酸的存在下与亚硝酸钠作用生成重氮盐的反应。 7、硝化剂：单一硝酸、硝酸和各种质子酸、有机酸、酸酐及各种Lewis酸的混合物。 8、生成硝基烷烃的难易顺序： 卤代烃中卤素被取代的顺序： 9、DMF: DMSO: 10、常用的重氮化试剂有哪些？NaNO2+HCl/H2SO4 第三章卤化反应 1、Ph上取代基对卤化反应的影响 ①催化剂的影响；

有机化学十种反应类型详细总结

一、取代反应 定义：有机物分子里的某些原子或原子团被其它原子或原子团所代替的反应称为取代反应。 在中学化学中，取代反应包括卤代、酯化、水解、硝化和磺化等很多具体的类型。分例如下： 1、与卤素单质的取代------发生该类反应的有机物包括：烷烃、烯烃、芳香烃、醇、酚等。例如： (1)．（在适当的条件下，烷烃的取代反应是可以逐步进行的，得到一系列的 混合物）。 (2)． (3)．CH 2＝CH －CH 3 + Cl 2 CH 2＝CH －CH 2－Cl + HCl (4)． (5)．+ 2HCl 2、与混酸的硝化反应（苯及其同系物、苯酚、烷烃等均能发生硝化反应）。如： (1)． + HNO 2 －NO 2 + H 2O (2)． (3)． 环己烷对酸、碱比较稳定，与中等浓度的硝酸或混酸在低温下不发生反应，与稀硝酸在100℃以上的封管中发生硝化反应，生成硝基环己烷。在铂或钯催化下，350℃以上发生脱氢反应生成苯。环己烷与氧化铝、硫化钼、古、镍-铝一起于高温下发生异构化，生成甲基戌烷。与三氯化铝在温和条件下则异构化为甲基环戊烷。 低碳硝基烷的工业应用日益广泛。在使用原料上，以丙烷硝化来制取是合理的途径。在工艺方面,国外较多的是以硝酸为硝化剂的气相硝化工艺，已积累了较丰富的工业经验。有代表性的反应器则是多室斯登该尔反应器。国内迄今有关硝基烷的生产和应用研究均进行得不多，这是应该引起我们充分注意的。 (4)．CH 3－CH 2－CH 3(气) + HNO 3(气) CH 3－CH 2－CH 2－NO 2 + H 2O 3、与硫酸的磺化反应（苯、苯的衍生物, 几乎均可磺化）。如： (1)． (2)． (邻、对位产物为主) 4、羧酸和醇的酯化反应 光照 浓硫酸 △ 100℃ + +

缩合剂种类及工作原理

库化合物制备中的缩合反应及缩合剂 库化合物制备中常用到的反应是胺化反应，常见的胺化反应即酸和胺发生反应，如下图： 但有时这种反应难以发生，需要加入缩合剂（coupling agents ），以促进反应进行，大致反应原理如下： 常见的缩合剂种类如下表：

下面简单介绍这些缩合剂各自的特点。 1.HBTU因其反应的产率较高而被广泛应用。它需要在水溶性的环境下进行反应，所以 若反应的中间产物是水溶性的，则要避免使用HBTU。下图是其副反应： 2. DMC DMC不需要水溶性的环境，所以当存在水溶性的中间体或产物时可优先考虑它，同时它适用于有空间位阻的羧酸的缩合反应。但它的缺点是每批之间的重现性不够好，同时当它参加的不是第一步反应时最好避免使用。下面是其反应的副产物： 3. HOBT它的使用相对较少。主要原因是它很容易分解。 4.HATU与HBTU相比，它的活性更高，当一些胺的反应活性不够时，可使用HATU 来加速反应。但它的价格约是HBTU的两倍。 5.DCC DCC会产生一种不溶于有机溶剂的副产物（但溶于醇类）。另外DCC会引起外 消旋作用，故不可用于手性化合物的制备。同时，DCC自身会重组生成一种副产物。它主要和其他缩合剂组合来使用。下图是它产生的不溶于有机溶剂的副产物： 6. CDI CDI可形成相对较稳定的中间体，同时对位阻较小的胺有一定的选择性。（shows selectivity towards less sterically hindered amines.），它可以在无水DMF和DMA中制备得到，且可以当作储备液来稀释酸（even be used as a stock solution to dilute acids.），CDI对workup没有要求，所以对水溶性的中间体和产物来说，它是个很好的缩合剂。下图是CDI的反应机理：

新编整理有机反应类型小结 有机反应类型归纳

有机反应类型小结有机反应类型归纳 随着高考制度的改革，XX年的高考由山东省统一命题改为全国统一命题，有机化学在化学教学中显得尤为重要，分值占到了27分，有机化学知识点比较多，现将其中一个知识点――有机反应类型的有关知识总结一下。 １取代反应 定义：有机化合物中的某些原子（或原子团）被其它原子（或原子团）所替代的反应。特征：两种物质互相交换原子或原子团，下以上一，有进有出。常见取代反应有：①烷烃卤代。如：CH4+Cl2CH3Cl+HCl； ②苯及其同系物（卤代、硝化、磺化）。如：+HNO3+H2O；③卤代烃的水解反应。如：CH3Cl+H2OCH3OH+HCl；④醇（与HX、分子间脱水成醚）。如：C2H5OH+HBrC2H5Br+H2O，2CH3CH2OHC2H5OC2H5+H2O。⑤苯酚与浓溴水。如：+Br2+HBr。 ⑥醇与酸的酯化反应。CH3CH2OH+CH3COOHCH3COOC2H5+H2O。⑦酯的水解反应（皂化反应）。如：CH3COOC2H5+H2OCH3COOH+C2H5OH。2加成反应 定义：有机物分子中不饱和碳原子跟其它原子（或原子团）直接结合成新物质的反应。特征：①物质“多变一”只进不出。②化合物不饱和程度降低（或消失）。 常见加成反应：①烯、炔、苯及不饱和烃的衍生物与氢气、卤素、卤化氢、水等反应；如：R-CH=CH2+H2R-CH2-CH3再如：R-C≡CH+HClR-CH=CHCl。②醛和酮、葡萄糖与氢气的反应等；如：

CH3CHO+H2CH3CH2OH。 ３消去反应 定义：有机物分子中脱去小分子（H2O、HX等）生成不饱和化合物的反应。特征：①化合物“一变多”②化合物不饱和程度增大。常见消去反应：①醇分子内脱水制烯；如：C2H5OHCH2=CH2↑+H2O②卤代烃分子内脱卤化氢生成烯；如：C2H5Cl+NaOHCH2=CH2↑+H2O+NaCl。 ４氧化反应 定义：有机分子中加氧或去氢的反应。常见氧化反应：①有机化合物的燃烧反应；②强氧化剂（如KMnO4）同烯、炔及其衍生物、苯的同系物反应；如：R-CH=CH2RCOOH+CO2③加氧氧化（如：由醛生成酸）；如：2CH3CHO+O22CH3COOH④去氢氧化（如：醇生成醛）；如：2CH3CH2OH+O22CH3CHO+2H2O。 ５还原反应 定义：有机物分子中加氢或去氧的反应。常见还原反应： ①加氢还原；如：烯、炔及其衍生物加氢；苯环加氢还原；醛加氢还原成醇；如：CH3CHO+H2CH3CH2OH②去氧还原；如：CH3COOHCH3CH2OH；再如： （注意，该反应不是取代反应）。 ６酯化反应（本质是取代反应） 定义：酸与醇作用生成酯和水的反应。 ７水解反应（本质是取代反应） 定义：有机物在有水参加时，分解为两种或多种物质的反应；如：酯与油脂的水解；卤代烃的水解；二糖及多糖的水解；蛋白质的水解。

中学常见的缩聚反应

中学常见的缩聚反应 一、缩聚反应的定义 缩聚反应，是一类有机化学反应，是具有两个或两个以上官能团的单体，相互反应生成高分子化合物，同时产生有简单分子（如H2O、HX、醇等）的化学反应。兼有缩合出低分子和聚合成高分子的双重含义，反应产物称为缩聚物（是混合物）。缩聚反应本质可看作为取代。 二、缩聚反应特征和分类 1．特征 缩聚反应通常是官能团间的聚合反应 比如说氨基酸脱水缩合就是一个典型的缩聚反应，反应中有低分子副产物产生，如水、醇、氨等。缩聚物中往往留有官能团的结构特征, 如-OCO- -NHCO- ，故大部分缩聚物都是杂链聚合物。缩聚物的结构单元比其单体少若干原子，故分子量不再是单体分子量的整数倍。缩聚反应即缩合聚合反应，单体经多次缩合而聚合成大分子的反应。该反应常伴随着小分子的生成。具有两个或两个以上官能团的单体，相互反应生成高分子化合物，同时产生有简单分子(如H2O、HX、醇等)的化学反应。如：甲醛跟过量苯酚在酸性条件下生成酚醛树脂(线型)，在碱性和甲醛过量条件下，则生成网状高分子。再如：由对苯二甲酸和乙二醇生成聚酯树脂。缩聚反应是合成高分子化合物的基本反应之一，在有机高分子化工领域有重要应用 2.分类 按键合基团分类： 酚醛树脂 脲醛树脂 聚烷烃 有机硅树脂 三、应用示例 2013年北京卷

25．(17分) 可降解聚合物P的合成路线如下： （7）聚合物P的结构简式为_________________________ 变式训练： 2014年北京西城区高三一模

25．（17分）以乙炔或苯为原料可合成有机酸H2MA ，并进一步合成高分子化合物PMLA 。 I ．用乙炔等合成烃C 。 （1）A 分子中的官能团名称是 、____。 （2）A 的一种同分异构体属于乙酸酯，其结构简式是____。 （3）B 转化为C 的化学方程式是____，其反应类型是一 。 II ．用烃C 或苯合成PMLA 的路线如下。 （4）1 mol 有机物H 与足量NaHC03溶液反应生成标准状况下的C02 44．8 L ，H 有顺反异构，其反式结构简式是____。 （5）E 的结构简式是____。 （6）G 与NaOH 溶液在加热条件下反应的化学方程式是 。 （7）聚酯PMLA 有多种结构，写出由H 2MA 制PMLA 的化学方程式（任写一种）____ 。 HOOCCH2CH(-OH)-COOH 的缩聚产物 2014年海淀区高三一模 25．（16分）高分子材料PET 聚酯树脂和PMMA 的合成路线如下： 2 C CH 3 3 n （PMMA ） 已知： Ⅰ. RCOOR’+ R’’18OH RCO 18OR’’+R’OH（R 、R’、R’’代表烃基） Ⅱ. - 2+ R C O R R C COOH OH R （R 、R ’代表烃基） ’ ’

有机反应类型归纳

有机反应类型归纳 1．取代反应 有机物分子里的某些原子或原子团被其它原子或原子团所代替的反应叫取代反应。概念要点：①是一类有机反应；②是原子或原子团与另一原子或原子团之间的交换；③两种物质反应，生成两种物质，原子或原子团有上有下；④反应前后有机物的空间结构没有发生变化； ⑤取代反应总是发生在单键上；⑥这是饱和化合物的特征反应。 以下的各种反应都属于取代反应。 （1）卤代反应：烷烃的卤代，苯的卤代，苯酚的卤代，醇和氢卤酸反应生成卤代烃。 （2）硝化反应：苯系芳烃的硝化，苯酚的硝化。 （3）磺化反应：苯的磺化。 （4）酯化反应：酸和醇在浓硫酸的作用下,生成酯和水的反应。包括醇和羧 酸或无机含氧酸的酯化，纤维素与乙酸或硝酸的酯化。 （5）水解反应：有机化合物通过断键分别结合水中的氢原子和羟基（-OH）的反应。卤代烃、酯、二糖和多糖、蛋白质能发生水解反应。 （6）成醚反应：两个醇分子间脱水生成醚。 2．加成反应 有机物分子不饱和的碳原子跟其它原子或原子团直接结合生成别的物质的反应叫加成反应。概念要点：①加成反应发生在不饱和（碳）原子上；②该反应总是发生在不饱和键中键能较小的键上；③该反应中加进原子或原子团，只生成一种有机物（相当于化合反应），原子或原子团只上不下；④加成前后有机物的结构将发生变化，烯烃变成烷烃时，结构由平面型变成立体型；炔烃变成烯烃时，结构由直线型变平面型；⑤加成反应是不饱和化合物的特征反应。 常见的加成反应有烯、炔和二烯烃等不饱和烃的加成，苯系芳烃的加成，醛的加氢，油酸的加成，油脂的加氢硬化等。 3．消去反应 有机化合物在适当的条件下，从一个分子里脱去一个小分子（如水、卤化氢等分子），而生成不饱和（双键或三键）化合物的反应叫消去反应。概念要点：①消去反应发生在分子