In Vitro Cell.Dev.Biol.—Plant36:47–50,January–February2000
?2000Society for In Vitro Biology
1054-5476/00$10.00?0.00
IMPROVEMENT OF ENGLISH WALNUT SOMATIC EMBRYO GERMINATION AND CONVERSION BY DESICCATION TREATMENTS AND PLANTLET DEVELOPMENT BY LOWER MEDIUM SALTS
HAORU TANG1,2*,ZHENGLONG REN1and GABI KRCZAL2
1College of Forestry and Horticulture,Sichuan Agricultural University,Ya’an,625014Sichuan,China,
2Zentrum Gru¨ne Gentechnik,Staatliche Lehr-und Forschungsanstalt,D-67435Neustadt an der Weinstra b e,Germany
(Received6August1999;accepted1November1999;editor M.R.Becwar)
S ummary
Well-developed somatic embryos were selected from a repetitively somatic embryo line derived from embryonic axes of
immature zygotic embryos of English walnut‘No.120’(Juglans regia L.)for germination and conversion studies.In
germinating dishes,somatic embryos germinated into only shoots,only roots,or both shoots and roots.Without any
pretreatment,28%somatic embryos germinated,while those treated with2.5–5.0mg l?1(7.2–14.4m mol)gibberellic
acid(GA3)germinated at25–28%and those receiving a cold treatment of2–3mo.at3–4?C germinated at30–43%.
However,only4–19%of the germinating embryos showed both shoots and roots.Treated with desiccation,either with
CaCl2·6H2O or Ca(NO3)2·4H2O at20?C in the dark for3d,somatic embryos germinated at85–91%,57–69%of which
had both shoots and roots.Treatment with2mo.cold storage in combination with desiccation using Ca(NO3)2·4H2O
resulted in92%of somatic embryos germinating,70%of which showed both shoots and roots.No significant differences
were observed between solid and liquid germination media.After transferring the germinating embryos to plantlet
development media,52–63%of those with both shoots and roots developed into plantlets while11%with only shoots or
9%with only roots converted into plantlets.Plantlet development was improved by using lower medium salts and sucrose
concentrations.The addition of activated charcoal enhanced root development,particularly root branching.Of131plants
transplanted,91plants were acclimatized to a greenhouse.
Key words:plant regeneration;Juglans regia;dehydration;synthetic seeds.
I ntroduction
Biotechnology has been expected to assist plant breeding programs,but applications of biotechnology to plant breeding have frequently been limited by a lack of reliable systems for regenerating transformed plant cells.Somatic embryogenesis has been considered as a useful system for genetic transformation not only because somatic embryos can be induced to repetitively undergo somatic embryogenesis,but also the secondary somatic embryos can be germinated into plants.Successful somatic embryogenesis has already been achieved in various cells,tissues and organs from numerous plant species(Thorpe,1995);however, reports of the recovery of transgenic plants from somatic embryos are rare,partially due to the low efficiency of somatic embryo germination and conversion.In fact,low efficiency of somatic embryo germination and conversion has still remained a significant barrier affecting many of the embryogenic systems described (Merkle et al.,1995).
It has been known for some time that treatments of matured somatic embryos with gibberellic acid(GA3),abscissic acid(ABA), chilling,etc.,can induce germination.In Juglans,complete plants have been regenerated from somatic embryos of Juglans regia after
a cold treatment of2–4mo.at2–4?C(Tulecke and McGranahan,
1985).However,Lee et al.(1988)and Deng and Cornu(1992) obtained a very low conversion efficiency for somatic embryos of Juglans regia and Juglans nigra?Juglans regia,respectively.
Recently,desiccation treatment has been developed for enhancing somatic embryo germination and conversion of Vitis longii(Gray, 1987),Dactylis glomerata(Gray et al.,1987),Glycine max (Hammatt and Davey,1987;Parrott et al.,1988),Carya illinoensis (Wetzstein et al.,1989)and Picea glauca?Picea engelmannii (Roberts et al.,1990).Deng and Cornu(1992)have successfully exploited this for promoting the germination of somatic embryos of Juglans nigra?Juglans regia.Our work was directed to investigate the effect of desiccation on the germination of somatic embryos of Juglans https://www.doczj.com/doc/1c16398282.html,parisons were made with cold storage and GA3treatments.The influences of medium salts,sucrose concentrations,and activated charcoal on plantlet development were also investigated.
M aterials and M ethods
Somatic embryo line.A repetitively somatic embryo line,derived from embryonic axes of immature zygotic embryos of English walnut‘No.120’(Juglans regia L.)(Tang et al.,1999a),was used in this study.This line has been maintained by a2-wk interval subculture on a basal DW medium (Tang et al.,1999b)at24?C in the dark for more than half a year.The newly formed somatic embryos were isolated and cultured on a basal DW medium 47
*Author to whom correspondence should be addressed:Email htang.slfa-nw@agrarinfo.rpl.de
48TANG ET AL.
for2–3wk prior to germination treatments.Well developed somatic embryos,4–5mm in length,were selected for germination and conversion. Pretreatments to promote germination.
1.Cold treatments:Somatic embryos placed on basal DW medium with or
without0.5%activated charcoal were stored at3–4?C in the dark for2–3mo.prior to germination treatments.
2.Desiccation treatments:Somatic embryos were placed in empty petri dishes
(94?16mm,20–30embryos each dish).One dish containing somatic embryos along with one80ml beaker containing about50ml of a supersaturated solution of either CaCl2·6H2O or Ca(NO3)2·4H2O was placed in an autoclaved Duran–Schott jar(80?150mm).The jars were sealed tightly with4–5layers of Parafilm and put at20?C in the dark for 3d.At a constant20?C,the CaCl2·6H2O created a relative humidity of about32%,the Ca(NO3)2·4H2O about55%(Winston and Bates,1960).
3.Cold treatment plus desiccation treatment:Following2mo.cold storage
at3–4?C in the dark,somatic embryos were treated with a desiccation of Ca(NO3)2·4H2O as described above.
Germination treatments.Following pretreatments,somatic embryos were placed on a basal DKW medium solidified with2.2g l?1Gelrite(25ml medium per94?16mm petri dish)or an autoclaved Macherey–Nagel filter compress(85mm in diameter,2layers in a94?16mm petri dish)soaked with20ml liquid DKW medium.In experiments involving gibberellic acid (GA3,Sigma),a filter-sterilized GA3solution was added to an autoclaved DKW medium solidified with2.2g l?1Gelrite(25ml medium per94?16mm petri dish)to a concentration of2.5or5mg l?1(7.2or14.4m mol).The basal DKW medium used contained30g l?1sucrose(pH5.5)and was autoclaved at 115?C for25min.Somatic embryos without pretreatment were used as controls.Somatic embryos germinated in a growth room set at24?C with a16-h photoperiod and a photon flux density of about75m mol m?2s?1,provided by cool white fluorescent lamps.This experiment was repeated three times with 2–3replicates(individual petri dishes),14–16somatic embryos each,and data were analyzed using Duncan’s multiple range test.
Plantlet development.After3wk on germination media,the germinating somatic embryos were transferred to the following six media solidified with 2.2g l?1Gelrite(pH5.5)(35ml medium in a175ml baby food jar,four germinating somatic embryos per jar or100ml medium in a1/2l Round–Weck jar,five germinating somatic embryos per jar)for plantlet development.
1.DKW 3X0%sucrose;
2.DKW 3X0%sucrose?0.5%activated charcoal;
3.DKW 0X5%sucrose;
4.DKW 0X5%sucrose?0.5%activated charcoal;
5.1a2DKW 0X5%sucrose;and
6.1a2DKW 0X5%sucrose?0X5%activated charcoal.
Plantlet growth was evaluated at4wk post-treatment by measuring their shoot height,numbers of leaves,main root length,roots with branches and numbers of branches.
Transplantation of plants.After washing thoroughly with water, complete plants with3–4leaves and well-developed roots were transplanted to plastic pots(11cm in diameter)containing Floration1compost (Floragard?GmbH,Germany)(1plant per pot)and watered thoroughly. Plants were then covered with transparent plastic bags and placed in a growth room as mentioned above.Over a3–4wk period,the bags were perforated,then removed.One week later,the plants were moved to greenhouse for further development.
R esults
In germination dishes,somatic embryos first showed an elongation of the root apex and then an emergence of a green shoot.Three types of germinating embryos(only shoots,only roots,and both shoots and roots)were observed and recorded in Table 1.Without any pretreatment,28%of somatic embryos germinated,but only4–6% of them showed both shoots and roots.Treated with GA3,somatic embryos germinated at25–28%,whilst treated with cold storage they germinated at30–43%.However,only5–19%of them had both shoots and roots.Treated with desiccation,either with CaCl2·6H2O or Ca(NO3)2·4H2O,85–91%of somatic embryos germinated and57–69%showed both shoots and roots.Treated with both cold storage and desiccation,somatic embryos germinated about1wk earlier than those with cold storage or desiccation alone and the percentages of the germinating embryos and the embryos with both shoots and roots were significantly higher than those with cold storage(P b0X01)but not significantly higher than those with desiccation.Fig.1illustrates the germination responses of somatic embryos to different treatments after a3wk period.No significantly different germination rates were observed between the solid and liquid germination media except those with cold storage treatments,in which somatic embryos germinated at significantly higher rates in filter compress supported liquid medium than on Gelrite-solid medium(P b0X05).
After transferring the germinating embryos into plantlet develop-ment media,those with only shoots resulted in11%plantlets and 50%shoot cultures whereas those with only roots resulted in only 9%plantlets.Between52%and63%of those with both shoots and roots converted into plantlets(Table2).No significantly different conversion rates were found among the six different media; nevertheless lowering medium salts and sucrose concentrations
TABLE1
EFFECTS OF PRETREATMENTS AND GERMINATION MEDIA ON SOMATIC EMBRYO GERMINATION OF ENGLISH WALNUT(JUGLANS REGIA L.)
Germination medium b
No.of
embryos tested
Total and types of embryos germinated(%)a
Pretreatment Total Shoots only Roots only Shoots?roots None Liquid7428X17?Z5?y6X
Solid7628X14?Z10??zy4X
2.5mg l?1GA37028X15?Z8?zy5X
5.0mg l?1GA37025X13?z6?zy6X Cold storage Liquid10943Y6?zy18?zy19Y
Solid6830X0?Yy23?z7X Desiccation with CaCl2·6H2O Liquid9891Z13?z21?zy57Z
Solid8785Z18?Z8?zy59Z Desiccation with Ca(NO3)2·4H2O Liquid9891Z15?Z14?zy62Z
Solid8891Z7?zy15?zy69Z Cold storage+desiccation with Ca(NO3)2·4H2O Solid6092Z9?zy13?zy70Z
a Means within a column followed by the same letter are not significantly different(z Y y 0X05;Z Y Y 0X01)by Duncan’s multiple range test.
b The germination medium is a basal DKW containing30g l?1sucrose solidified with2.2g l?1Gelrite(solid)or supported with filter compress(liquid).The medium containing GA3is solidified with2.2g l?1Gelrite.
49 IMPROVEMENT OF ENGLISH WALNUT SOMATIC EMBRYO GERMINATION
enhanced shoot and root development and resulted in plantlets with improved growth performance(Fig.2).The addition of activated charcoal resulted in better root development,by stimulating more root branches(Table2).
After4wk development on plantlet development media,131 plantlets with3–4leaves and well-developed roots were selected and transplanted to pots and91plants were acclimatized to greenhouse conditions(Fig.3).
D iscussion
Plant regeneration is the cornerstone of in vitro culture.Without plant regeneration,many in vitro culture studies would have no practical value.Somatic embryos are characteristic of bipolar structures nominally capable of regenerating plants,but poor germination and conversion are typical in many cases.Improvement of somatic embryo germination and conversion is generally a long-term effort,as many factors contribute to germination and conversion capacity(Merkle et al.,1995).While several methods have been reported to improve the rate of somatic embryo germination and conversion,one general approach is to attempt to mimic the conditions experienced by zygotic embryos.Desiccation, a characteristic of zygotic embryogenesis in planta,is a plausible treatment for terminating embryogenic developmental processes and triggering the germination and seedling developmental programs.Following the pioneering research by Gray(1987)and Gray et al.(1987)with Vitis longii and Dactylis glomerata somatic embryos,desiccation has been used to enhance somatic embryo germination and conversion for a number of species such as Picea glauca?Picea engelmannii(Roberts et al.,1990),Picea glauca (Attree et al.,1987),Glycine max(Hammatt and Davey,1987), Arachis hypogaea(Durham and Parrott,1992),Medicago sativa (Anandarajah and McKersie,1990)and Triticum aestivum(Carman, 1988).In Juglans nigra?Juglans regia,Deng and Cornu(1992) reported that about45%of the desiccated somatic embryos germinated as opposed to about10%of cold or GA3-treated somatic embryos.Our results with Juglans regia somatic embryos showed that desiccation significantly(P b0X01)increased the
TABLE2
THE INFLUENCE OF MEDIUM NUTRIENTS,SUCROSE CONCENTRATIONS AND ADDITION OF ACTIVATED CHARCOAL ON CONVERSION OF GERMINATING SOMATIC EMBRYOS AND PLANTLET DEVELOPMENT OF ENGLISH WALNUT(JUGLANS REGIA L.)
Plantlet growth performance a
No.of
embryos tested
%of
conversion
Shoot growth Root growth
Medium b Height of shoots No.of leaves Length of main roots%of main roots with branches No.of branches A4858 1.1^0.12 2.2^0.18 5.2^0.4150 2.4^0.45 B4255 1.2^0.22 2.5^0.24 5.6^0.7357 3.8^0.83 C4260 1.1^0.17 2.8^0.25 5.6^0.7444 2.7^0.81 D46520.9^0.12 3.0^0.25 4.7^0.6363 2.3^0.43 E4558 1.2^0.10 3.5^0.26 5.5^0.3162 3.1^0.38 F4663 1.3^0.13 3.4^0.24 6.0^0.4966 3.9^0.74
a Mean^SE.
b A:DKW?3%sucrose;B:DKW?3%sucrose?0.5%activated charcoal;C:DKW?0.5%sucrose;D:DKW?0.5%sucrose?0.5%activated
charcoal;E:1/2DKW?0.5%sucrose;F:1/2DKW?0.5%sucrose?0.5%activated
charcoal.
F ig.1.A comparison of different treatments on the germination of walnut somatic embryos after a3wk germination period on a basal DKW medium solidified with2.2g l?1Gelrite(petri dishes,94mm in diameter). Upper:No pretreatment(control;left)and a3d desiccation with Ca(NO3)2·4H2O(right).Lower:Cold storage of3mo.at3–4?C(left)and a 5mg l?1GA3treatment
(right).
F ig.2.Plantlets showing improved growth performance after4wk on 1/2DKW medium with0.5%sucrose(1/2l Round-Weck jar,108mm in diameter).
50TANG ET AL.
germination rates and,most importantly,the rates of the germinating embryos with both shoots and roots,as necessary to obtain high conversion rates.
It has been reported that ABA accumulates during the maturation of somatic embryos,which induces somatic embryo dormancy (Rajasekaran et al.,1982).Germination cannot take place until the endogenous ABA decreased to an appropriate level.Chilling treatments can markedly reduce the endogenous ABA levels and promote germination (Rajasekaran et al.,1982).Other studies of somatic embryo germination found that the levels of GA 3and GA precursors can increase during the chilling process as ABA levels decrease (Pearce et al.,1987),and exogenously supplied GA 3stimulates germination.In walnut,complete plants have been regenerated from somatic embryos of Juglans regia after a cold treatment (Tulecke and McGranahan,1985).However,our studies showed that somatic embryos of Juglans regia germinated poorly when treated with cold storage alone.The addition of GA 3did not improve the poor germination.Similar results have been reported in Juglans nigra ?Juglans regia (Deng and Cornu,1992)and Juglans regia (Lee et al.,1988).
The ability to obtain germinating somatic embryos is not necessarily an indicator of continued growth and vigor,since plantlets removed from germination conditions often display poor or aberrant subsequent growth and vigor.This might suggest that further post-germination treatments are required.The germination of somatic embryos is often reported,but little mention is made of the continued development of resulting plantlets.McGranahan et al.(1987)reported that the root growth of the germinating somatic embryos of Juglans regia was improved by transfer to a simple White medium with lowered sucrose and added charcoal.This is in agreement with our results that plantlets grew much better on the half-strength DKW medium with a lowered sucrose concentration than on the full-strength DKW medium.The addition of activated charcoal aided plantlet growth in root development,especially by promoting root branches,which resulted in plantlets with more vigor.The use of lower medium salts during plantlet development might suggest that different stages of plant development may require different types or concentrations of basal salts.
A cknowledgments
The authors thank Baumschule Anton Schott,Leiselheim am Kaiserstuhl,Germany for supplying original walnut materials.We
would like to thank Dr.Jehle and Dr.Reustle for help in manuscript preparation,and Mr.Wahl for photography.
R eferences
Anandarajah,K.;McKersie,B.D.Manipulating the desiccation tolerance
and vigor of dry somatic embryos of Medicago sativa L.with sucrose,heat shock and abscisic acid.Plant Cell Rep.9:451–455;1990.
Attree,S.M.;Bekkaoui,F.;Dunstan,D.I.;Fowke,L.C.Regeneration of
somatic embryos from protoplasts isolated from an embryogenic suspension of white spruce (Picea glauca ).Plant Cell Rep.6:480–483;1987.
Carman,J.G.Improved somatic embryogenesis in wheat by partial
stimulation of the in-ovulo oxygen,growth-regulator and desiccation environments.Planta 175:417–424;1988.
Deng,M.D.;Cornu,D.Maturation and germination of walnut somatic
embryos.Plant Cell https://www.doczj.com/doc/1c16398282.html,.Cult.28:195–202;1992.
Durham,R.E.;Parrott,W.A.Repetitive somatic embryogenesis in liquid
cultures of peanut.Plant Cell Rep.11:122–125;1992.
Gray,D.J.Quiescence in monocotyledonous and dicotyledonous somatic
embryos induced by dehydration.HortScience 22:810–814;1987.
Gray,D.J.;Conger,B.V.;Songstad,D.D.Desiccation quiescent somatic
embryos of orchardgrass for use as synthetic seeds.In Vitro Cell.Dev.Biol.25:1173–1178;1987.
Hammatt,N.;Davey,M.R.Somatic embryogenesis and plant regeneration
from cultured zygotic embryos of soybean (Glycine max L.).J.Plant Physiol.128:219–226;1987.
Lee,B.C.;Shim,S.Y.;Lee,S.K.Mass propagation of somatic embryos in
Juglans regia L.(English walnut).Res.Rep.Inst.For.Genet.Korea 24:99–106;1988.
McGranahan,G.H.;Driver,J.A.;Tulecke,W.Tissue culture of Juglans .
In:Bonga,J.M.;Durzan,D.J.,eds.Cell and tissue culture in forestry,vol.3.Boston:Martinus Nijhoff;1987:261–271.
Merkle,S.A.;Parrott,W.A.;Flinn,B.S.Morphogenic aspects of somatic
embryogenesis.In:Thorpe,T.A.,ed.In vitro embryogenesis in plants (Current plant science and biotechnology in agriculture,vol.20).Dordrecht:Kluwer Academic Publishers;1995:155–203.
Parrott,W.A.;Dryden,G.;Vogt,S.;Hildebrand,D.F.;Collins,G.B.;
Williams,E.G.Optimization of somatic embryogenesis and embryo germination in soybean.In Vitro Cell.Dev.Biol.24:817–820;1988.
Pearce,D.;Pharis,R.P.;Rajasekaran,K.;Mullins,M.G.Effects of chilling
and ABA on (3H)gibberellin A 4metabolism in somatic embryos of grape (Vitis vinifera L.?V.rupestris Scheele).Plant Physiol.80:381–385;1987.
Rajasekaran,K.;Vine,J.;Mullins,M.G.Dormancy in somatic embryos and
seeds of Vitis :changes in endogenous abscisic acid during embryogeny and germination.Planta 154:139–144;1982.
Roberts,D.R.;Sutton,B.C.S.;Flinn,B.S.Synchronous and high frequency
germination of interior spruce somatic embryos following partial drying at high relative humidity.Can.J.Bot.68:1086–1090;1990.
Tang,H.-R.;Ren,Z.-L.;Reustle,G.M.;Krczal,G.Optimizing secondary
somatic embryo production in English walnut (Juglans regia L.).The Fourth International Walnut Symposium,Bordeaux,France 1999.Acta Hortic.;2000(in press).
Tang,H.-R.;Ren,Z.-L.;Wallbraun,M.;Reustle,G.M.;Krczal,G.Somatic
embryogenesis of English walnut and recovery of transgenic somatic embryos after Agrobacterium -mediated transformation.Symposium on Fruit Breeding and Genetics,Eucarpia Fruit Breeding Section,Dresden,Germany,1999.Acta Hortic.;2000(in press).
Thorpe,T.A.In vitro embryogenesis in plants (Current plant science and
biotechnology in agriculture,vol.20).Dordrecht:Kluwer Academic Publishers;1995.
Tulecke,W.;McGranahan,G.H.Somatic embryogenesis and plant
regeneration from cotyledons of walnut,Juglans regia L.Plant Sci.40:57–63;1985.
Wetzstein,H.Y.;Ault,J.R.;Merkle,S.A.Further characterization of
somatic embryogenesis and plant regeneration in pecan (Carys illinoensis ).Plant Sci.64:193–201;1989.
Winston,D.W.;Bates,D.H.Saturated solutions for the control of humidity
in biological research.Ecology 41:232–237;
1960.
F ig .3.Plants derived from walnut somatic embryos growing after 4–5wk in a greenhouse (plastic pots,11cm in diameter).
英语演讲稿：未来的工作 这篇《英语演讲稿范文：未来的工作》，是特地，希望对大家有所帮助！ 热门演讲推荐：竞聘演讲稿 | 国旗下演讲稿 | 英语演讲稿 | 师德师风演讲稿 | 年会主持词 | 领导致辞 everybody good afternoon:. first of all thank the teacher gave me a story in my own future ideal job. everyone has a dream job. my dream is to bee a boss, own a pany. in order to achieve my dreams, i need to find a good job, to accumulate some experience and wealth, it is the necessary things of course, in the school good achievement and rich knowledge is also very important. good achievement and rich experience can let me work to make the right choice, have more opportunities and achievements. at the same time, munication is very important, because it determines whether my pany has a good future development. so i need to exercise their municative ability. i need to use all of the free time to learn
当今时代是一个自动化时代，交通灯控制等很多行业的设备都与计算机密切相关。因此，一个好的交通灯控制系统，将给道路拥挤、违章控制等方面给予技术革新。随着大规模集成电路及计算机技术的迅速发展，以及人工智能在控制技术方面的广泛运用，智能设备有了很大的发展，是现代科技发展的主流方向。本文介绍了一个智能交通灯系统的设计。该智能交通灯控制系统可以实现的功能有：对某市区的四个主要交通路口进行监控；各路口有固定的工作周期，并且在道路拥挤时中控中心能改变其周期；对路口违章的机动车能够即时拍照，并提取车牌号。在世界范围内，一个以微电子技术，计算机和通信技术为先导的，以信息技术和信息产业为中心的信息革命方兴未艾。而计算机技术怎样与实际应用更有效的结合并有效的发挥其作用是科学界最热门的话题，也是当今计算机应用中空前活跃的领域。本文主要从单片机的应用上来实现十字路口交通灯智能化的管理，用以控制过往车辆的正常运作。 The times is a automation times nowadays , traffic light waits for much the industry
equipment to go hand in hand with the computer under the control of. Therefore, a good traffic light controls system , will give road aspect such as being crowded , controlling against rules to give a technical improvement. With the fact that the large-scale integrated circuit and the computer art promptness develop, as well as artificial intelligence broad in the field of control technique applies, intelligence equipment has had very big development , the main current being that modern science and technology develops direction. The main body of a book is designed having introduced a intelligence traffic light systematically. The function being intelligence traffic light navar's turn to be able to come true has: The crossing carries out supervisory control on four main traffic of some downtown area; Every crossing has the fixed duty period , charges centre for being able to change it's period and in depending on a road when being crowded; The motor vehicle breaking rules and regulations to the crossing is able to take a photo immediately , abstracts and the vehicle shop sign. Within world range, one uses the microelectronics technology , the computer and the technology communicating by letter are a guide's , centering on IT and IT industry information revolution is in the ascendant. But, how, computer art applies more effective union and there is an effect's brought it's effect into play with reality is the most popular topic of conversation of scientific community , is also that computer applications is hit by the unparalleled active field nowadays. The main body of a book is applied up mainly from slicing machine's only realizing intellectualized administration of crossroads traffic light , use opera tion in controlling the vehicular traffic regularity.
关于坚持的英语演讲稿 Results are not important, but they can persist for many years as a commemoration of. Many years ago, as a result of habits and overeating formed one of obesity, as well as indicators of overall physical disorders, so that affects my work and life. In friends to encourage and supervise, the participated in the team Now considered to have been more than three years, neither the fine rain, regardless of winter heat, a day out with 5:00 time. The beginning, have been discouraged, suffering, and disappointment, but in the end of the urging of friends, to re-get up, stand on the playground. 成绩并不重要，但可以作为坚持多年晨跑的一个纪念。多年前，由于庸懒习惯和暴饮暴食，形成了一身的肥胖，以及体检指标的全盘失常，以致于影响到了我的工作和生活。在好友的鼓励和督促下，参加了晨跑队伍。现在算来，已经三年多了，无论天晴下雨，不管寒冬酷暑，每天五点准时起来出门晨跑。开始时，也曾气馁过、痛苦过、失望过，但最后都在好友们的催促下，重新爬起来，站到了操场上。 In fact, I did not build big, nor strong muscles, not a sport-born people. Over the past few years to adhere to it, because I have a team behind, the strength of a strongteam here, very grateful to our team, for a long time, we encourage each other, and with sweat, enjoying common health happy. For example, Friends of the several run in order to maintain order and unable to attend the 10，000 meters race, and they are always concerned about the brothers and promptly inform the place and time, gives us confidence and courage. At the same time, also came on their own inner desire and pursuit for a good health, who wrote many of their own log in order to refuel for their own, and inspiring. 其实我没有高大身材，也没健壮肌肉，天生不属于运动型的人。几年来能够坚持下来，因为我的背后有一个团队，有着强大团队的力量，在这里，非常感谢我们的晨跑队，长期以来，我们相互鼓励着，一起流汗，共同享受着健康带来的快
地理位置 位于墨西哥大学城以南的库库尔坎（Kukulcan），是玛雅文化前古典期晚期（公元前800年——公元前200年）中部高原文化的重要文化遗址之一，“库库尔坎”的原意是“舞蹈唱歌的地方”，或表示“带有羽毛的蛇神”。 建筑结构 “库库尔坎”金字塔是我们现在看到的早期墨西哥金字塔是一座用土筑成的 九层圆形祭坛，高29米 ，周边各宽55米多，周长250米左右，最高一层建有一座6米高的方形坛庙，库库尔坎金字塔高约30 米，四周环绕91 级台阶，加起来一共364级台阶，再加上塔顶的羽蛇神庙，共有365阶，象征了一年中的365 天。台阶的两侧宽达1米的边墙，北边墙下端，有一个带羽行的大蛇头石刻，蛇头高1.43米，长达1.80米，宽1.07米，蛇嘴里吐出一条大舌头，颇为独特。 这座古老的建筑，在建造之前，经过了精心的几何设计，它所表达出的精确度和玄妙而充满戏剧性的效果，令后人叹为观止：每年春分和秋分两天的日落时分，北面一组台阶的边墙会在阳光照射下形成弯弯曲曲的七段等腰三角形，连同底部雕刻的蛇头，宛若一条巨蛇从塔顶向大地游动，象征着羽蛇神在春分时苏醒，爬出庙宇。每一次，这个幻像持续整整3 小时22 分，分秒不差。这个神秘景观被称为“光影蛇形”。 每当“库库尔坎”金字塔出同蛇影奇观的时候，古代玛雅人就欢聚在一起，高歌起舞，庆祝这位羽毛蛇神的降临。 库库尔坎金字塔，是玛雅人对其掌握的建筑几何知识的绝妙展示，而金字塔旁边的天文台，更是把这种高超的几何和天文知识表现得淋漓尽致。 建造工艺 在没有金属工具、没有大牲畜和轮车的情况下，古代玛雅人却能够开采大量重达数十吨的石头，跋山涉水、一路艰辛地运到目的地，建成一个个雄伟的金字塔。金字塔最高的可达70米，其规模之巨大、施工难度之高，令人吃惊。 古代玛雅的金字塔和古埃及的金字塔在建筑形式上有着明显的不同。埃及的金字塔的塔顶是尖的，而玛雅金字塔却是平顶，塔体呈方形，底大顶小，层层叠叠，塔顶的台上还建有庙宇；在用途上也不一样：埃及金字塔是法老的陵墓，而玛雅的金字塔除个别外，一般是用来祭祀或观察天象的。除金字塔外，玛雅人还兴建了不少功能性强，技艺高的民用建筑，主要有：房屋（包括庙宇、府邸、民居等）、公共设施（球场、广场、集市等）、基础设施（桥梁、大道、码头、堤坝、护墙等）和水利工程（水渠、水库、水井、梯田）等。
与其他不少考研热门专业一样，英语专业研究生招生的研究方向设置非常细，不同学校的方向设置类别不一，名称也各异。 比如上海外国语大学英语语言文学专业下设有语言方向、文学方向、教学法方向、翻译学方向、口译学方向、英语国家文化方向、跨文化交际方向7个方向。而同样是外语类专业院校，北京外国语大学该专业设置的研究方向明显不同，广东外语外贸大学该专业设置的8个研究方向更与前两所学校无一相同。 在这种情况下，不少备考英语专业的同学对“如何选择研究方向”这样的问题一头雾水，也就不足为怪了。 就英语专业考研而言，外国语言文学下设置的二级学科很多，包括英语语言文学、俄语语言文学、法语语言文学、德语语言文学、日语语言文学、印度语言文学、阿拉伯语语言文学、欧洲语言文学、亚非语言文学、外国语言学及应用语言学、翻译学11个学科。其中，涉及英语专业的二级学科主要有3个：英语语言文学、外国语言学及应用语言学、翻译学。 一般院校的英语专业多设置英语语言文学和外国语言学及应用语言学两个专业，所以，英语专业考研的专业设置其实比较简单，一般就是两大专业。不过，这两个专业被不同学校细化研究方向以后，就变得复杂了。如前面说到的上海外国语大学英语语言文学专业下设有7个方向，这7个方向进一步细分，小的研究方向达37个之多。 英语专业的研究方向虽名目众多，却也并非杂乱无章，其设置仍是遵循一定规律的。粗略分析，这些研究方向可分为传统研究方向和新兴研究方向两大类。 传统研究方向 传统研究方向，顾名思义，指的是设置多年的老牌研究方向，这些研究方向一般学校都有开设。 1. 文学方向 开设学校：全国绝大部分招收英语专业研究生的学校。据2007年的招生统计，仅有17所招收英语专业研究生的学校没有开设文学方向。 研究内容：主要研究英美文学研究领域中的重大问题，目的在于提高文学素养、理论水平和研究能力。 就业方向：此方向开设学校多，招生人数较多，就业范围非常广泛，一般为教师、研究人员。所学课程：西方文论、美国经典文学、美国现当代文学、英国经典文学、文学批评、英国文学选读、美国文学选读、17～19世纪英国文学研究、希腊戏剧研究、英国长篇小说选读、美国长篇小说选读、英国诗歌选读、美国诗歌选读、英美散文鉴赏、王尔德戏剧欣赏、英国短篇小说欣赏、美国短篇小说鉴赏、英美戏剧鉴赏、中国文学史、中国古典文学选读等。 2. 语言学 开设学校：全国绝大部分招收英语专业研究生的学校。据2007年的招生统计，仅有9所招收英语专业研究生的学校没有开设语言学方向。 研究内容：语言学是我国高校近年来普遍设置的一个综合性的语言研究学科。主要学习语言学理论及语言在各种学科中的应用，不同学校侧重点有所不同。 通过大量阅读有关文献、论文和最新的研究成果报告，使学生对于语言学的形成和发展有进一步的了解，并了解现代语言学的最新动向和最新发展。语言学特别强调和重视研究生的广泛阅读，包括专业的外语期刊和近几年的语言学相关论文。 就业方向：该专业理论性较强，主要面向大中专教师及研究人员。 所学课程：语言学概论、语用学与话语分析、应用语言学、现代语法学、语义学、语用学、英语语体学与文体学、语篇分析等。 3. 英美文化研究 开设学校：南京大学、上海外国语大学、天津师范大学等。
英文 Because of the rapid development of our economy resulting in the car number of large and medium-sized cities surged and the urban traffic, is facing serious test, leading to the traffic problem increasingly serious, its basically are behaved as follows: traffic accident frequency, to the human life safety enormous threat, Traffic congestion, resulting in serious travel time increases, energy consumption increase; Air pollution and noise pollution degree of deepening, etc. Daily traffic jams become people commonplace and had to endure. In this context, in combination with the actual situation of urban road traffic, develop truly suitable for our own characteristics of intelligent signal control system has become the main task. Preface In practical application at home and abroad, according to the actual traffic signal control application inspection, planar independent intersection signal control basic using set cycle, much time set cycle, half induction, whole sensor etc in several ways. The former two control mode is completely based on planar intersection always traffic flow data of statistical investigation, due to traffic flow the existence of variable sex and randomicity, the two methods have traffic efficiency is low, the scheme, the defects of aging and half inductive and all the inductive the two methods are in the former two ways based on increased vehicle detector and according to the information provided to adjust cycle is long and green letter of vehicle, it than random arrived adaptability bigger, can make vehicles in the parking cord before as few parking, achieve traffic flowing effect In modern industrial production,current,voltage,temperature, pressure, and flow rate, velocity, and switch quantity are common mainly controlled parameter. For example: in metallurgical industry, chemical production, power engineering, the papermaking industry, machinery and food processing and so on many domains, people need to transport the orderly control. By single chip microcomputer to control of traffic, not only has the convenient control, configuration simple and flexible wait for an advantage, but also can greatly improve the technical index by control quantity, thus greatly improve product quality and quantity. Therefore, the monolithic integrated circuit to the traffic light control problem is an industrial production we often encounter problems. In the course of industrial production, there are many industries have lots of traffic equipment, in the current system, most of the traffic control signal is accomplished by relays, but relays response time is long, sensitivity low, long-term after use, fault opportunity increases greatly, and adopts single-chip microcomputer control, the accuracy of far greater than relays, short response time, software reliability, not because working time reduced its performance sake, compared with, this solution has the high feasibility. About AT89C51 (1)function characteristics description: AT89C51 is a low power consumption, high performance CMOS8 bit micro-controller, has the 8K in system programmable Flash memory. Use high-density Atmel company the beltpassword nonvolatile storage technology and manufacturing, and industrial 80S51 product instructions and pin fully compatible. Chip Flash allow program memory in system programmable, also suitable for conventional programmer. In a single chip, have dexterous 8 bits CPU and in system programmable Flash, make AT89C51 for many embedded control application system provides the high flexible, super efficient solution. AT89C51 has the following standard function: 8k bytes Flash, 256 bytes RAM, 32-bit I/O mouth line, the watchdog timer, two data pointer, three 16 timer/counter, a 6 vector level 2 interrupt structure, full-duplex serial port, piece inside crystals timely clock circuit. In addition, AT89C51 can drop to 0Hz static logic operation, support two software can choose power saving mode. Idle mode, the CPU to stop working, allowing the RAM, timer/counter, serial ports, interruption continue to work. Power lost protection mode, RAM content being saved, has been frozen, microcontroller all work stop, until the next interruption or hardware reset so far. As shown in
关于工作的优秀英语演讲稿 Different people have various ambitions. Some want to be engineers or doctors in the future. Some want to be scientists or businessmen. Still some wish to be teachers or lawers when they grow up in the days to come. Unlike other people, I prefer to be a farmer. However, it is not easy to be a farmer for Iwill be looked upon by others. Anyway,what I am trying to do is to make great contributions to agriculture. It is well known that farming is the basic of the country. Above all, farming is not only a challenge but also a good opportunity for the young. We can also make a big profit by growing vegetables and food in a scientific way. Besides we can apply what we have learned in school to farming. Thus our countryside will become more and more properous. I believe that any man with knowledge can do whatever they can so long as this job can meet his or her interest. All the working position can provide him with a good chance to become a talent. 1 ————来源网络整理，仅供供参考
Unit 2 Translation Put the following paragraphs into Chinese. When a woman is stressed she instinctively feels a need to talk about her feelings and all the possible problems that are associated with her feelings. When she begins talking she does not prioritize the significance of any problem. If she is upset, then she is upset about it all, (no mater it is) big and small. She is not immediately concerned with finding solutions to her problems but rather seeks relief by expressing herself and being understood. By randomly talking about her problems, she becomes less upset. 参考译文：女人有压力时，会直觉地需要找人谈自己的感受以及所有可能与之相关的问题。她一旦开始谈论，就不会顾虑到问题的优先顺序。而她一难过，不论大大小小的事都让她沮丧不已。她并不急于马上寻求解答，而宁可通过倾诉自我，获得理解来取得纾解。通过随意倾诉自己的问题，她会感觉好受一点。 Exercise Turn the following sentences into Chinese. 1. The improbable (pregnant) pregnancy was (some/ a pieces of) big news for the woman's family. 2. In reality, I am a great (admire) admirer of Maya. 3. Carlisle Street runs westward, across a great black bridge, down a hill and up again, by little shops and meat-markets, past single-storied homes, until suddenly it stops against a wide green lawn. 4. The fact that she was able to send a message was a hint. But I had to be cautious. 5. That day he was up before sunrise (sunrise: n./ vi.<-> sunset: n./ vi.). 参考译文： 1. 她竟然能怀孕，对她的家庭来说可是一条特大消息。 2. 事实上我对玛雅人佩服得五体投地。 3. 卡列斯尔大街往西伸展，越过一座黑色的大桥，爬下山岗又爬了上去，经过许多小铺和肉市，又经过一些平房，然后突然冲着一大片绿色草地中止了。 4. 她能够给我带个信儿这件事就是一个暗示。但是我必须小心谨慎。 5. 那天他在日出以前就起来了Unit 3 Part II Translation Put the following paragraphs into Chinese. Paris is enrolled in a "dual immersion" program at the Glenwood Elementary School here in which the pupils-half native Chinese, half English speakers—do their lessons in two languages. The program is indicative of one of the fastest-growing curriculum trends in U.S. schools: the study of Chinese. "Americans are used to hearing about people in other countries learning English. Now we're seeing the opposite trend," said Michael Levine, executive director of the Asia Society, which promotes international content in U.S. schools. "Parents and students are deciding that, since more people speak Mandarin than any other language, it might be a useful skill to have." 参考译文： 帕里斯参加了格兰乌德小学的“双语浸入式”项目，这个项目里的学生有一半的母语是汉语，有一半是英语，他们用两种语言上课。从这个项目可以看出美国学校里发展最迅速的一门课程：汉语学习。 “美国人习惯听到西他国家的人学习英语，现在我们看到了相反的趋势。”亚洲协会的执行会长迈克尔. 莱温说，该组织在美国学校里推行国际教学内容，“父母和学生们认为既然说汉语的人比任何其它语言多，那掌握汉语可能是一项有用的技能。” Exercise Turn the following sentences into Chinese. 1. Robin Hood (罗宾汉) often looted (robbed) the rich and helped the poor. 2. Ice (->icy) is not as dense (密度高的) as water and it therefore floats. 3. They have not done so well (idea->ideology->) ideologically (意识形态方面, 缺少新意), however, as (organ-> organize-> organization-> organizational) organizationally (组织方面). 4. It was a clear and unemotional (objective<->subjective) （expose->be exposed to sth.接触）exposition (说明) of the President's reasons for willing (愿意) to begin a
交通信号灯 当今，红绿灯安装在各个道口上，已经成为疏导交通车辆最常见和最有效的手段。社会的发展，人们的消费水平不断的提高，私人车辆不断的增加。人多、车多道路窄的道路交通状况已经很明显了。所以采用有效的方法控制交通灯是势在必行的。PLC 的智能控制原则是控制系统的核心，采用PLC把东西方向或南北方向的车辆按数量规模进行分档，相应给定的东西方向与南北方向的绿灯时长也按一定的规律分档. 这样就可以实现按车流量规模给定绿灯时长，达到最大限度的有车放行，减少十字路口的车辆滞流，缓解交通拥挤、实现最优控制，从而提高了交通控制系统的效率. PLC的应用正在不断地走向深入，同时带动传统控制检测日新月益更新。它具有结构简单、编程方便、可靠性高等优点，已广泛用于工业过程和位置的自动控制中。由于PLC具有对使用环境适应性强的特性，同时其内部定时器资源十分丰富，可对目前普遍使用的“渐进式”信号灯进行精确控制，特别对多岔路口的控制可方便地实现。因此现在越来越多地将PLC应用于交通灯系统中。 同时，PLC本身还具有通讯联网功能，将同一条道路上的信号灯组成一局域网进行统一调度管理，可缩短车辆通行等候时间，实现科学化管理。在实时检测和自动控制的PLC应用系统中，PLC往往是作为一个核心部件来使用。 .. 21世纪，PLC会有更大的发展。从技术上看，计算机技术的新成果会更多地应用于可编程控制器的设计和制造上，会有运算速度更快、存储容量更大、智能更强的品种出现；从产品规模上看，会进一步向超小型及超大型方向发展；从产品的配套性上看，产品的品种会更丰富、规格更齐全，完美的人机界面、完备的通信设备会更好地适应各种工业控制场合的需求；从市场上看，各国各自生产多品种产品的情况会随着国际竞争的加剧而打破，会出现少数几个品牌垄断国际市场的局面，会出现国际通用的编程语言；从网络的发展情况来看，可编程控制器和其它工业控制计算机组网构成大型的控制系统是可编程控制器技术的发展方向。目前的计算机集散控制系统DCS中已有大量的可编程控制器应用。伴随着计算机网络的发展，可编程控制器作为自动化控制网络和国际通用网络的重要组成部分，将在工业及工业以外的众多领域发挥越来越大的作用。
关于工作的英语演讲稿 【篇一：关于工作的英语演讲稿】 关于工作的英语演讲稿 different people have various ambitions. some want to be engineers or doctors in the future. some want to be scientists or businessmen. still some wish to be teachers or lawers when they grow up in the days to come. unlike other people, i prefer to be a farmer. however, it is not easy to be a farmer for iwill be looked upon by others. anyway,what i am trying to do is to make great contributions to agriculture. it is well known that farming is the basic of the country. above all, farming is not only a challenge but also a good opportunity for the young. we can also make a big profit by growing vegetables and food in a scientific way. besides we can apply what we have learned in school to farming. thus our countryside will become more and more properous. i believe that any man with knowledge can do whatever they can so long as this job can meet his or her interest. all the working position can provide him with a good chance to become a talent. 【篇二：关于责任感的英语演讲稿】 im grateful that ive been given this opportunity to stand here as a spokesman. facing all of you on the stage, i have the exciting feeling of participating in this speech competition. the topic today is what we cannot afford to lose. if you ask me this question, i must tell you that i think the answer is a word---- responsibility. in my elementary years, there was a little girl in the class who worked very hard, however she could never do satisfactorily in her lessons. the teacher asked me to help her, and it was obvious that she expected a lot from me. but as a young boy, i was so restless and thoughtless, i always tried to get more time to play and enjoy myself. so she was always slighted over by me. one day before the final exam, she came up to me and said, could you please explain this to me? i can not understand it. i
库库尔坎金字塔位于墨西哥尤卡坦半岛北部，是曾经古玛雅人留下的文明遗址。 库库尔坎在玛雅文化中是带羽蛇神的意思，被誉为是太阳的化身，即太阳神。羽蛇神主宰着晨星、发明了书籍、立法，而且给人类带来了玉米，还代表着死亡和重生，也是祭司们的保护神。古典时期，玛雅“真人”手持权杖，权杖一端为精致小形、中间为小人的一条腿化作蛇身、另一端为一蛇头。到了后古典时期，出现了多种变形，但基本形态完全变了，成为上部羽扇形、中间蛇身下部蛇头的羽蛇神形象。 羽蛇神与雨季同来，而雨季又与玛雅人种玉米的时间相重合，因而羽蛇神又成为玛雅农人最为崇敬的神明。在玛雅人眼中羽蛇神与犬神有同样高的地位 在现今留存的最大的玛雅古城奇岑－伊扎，库库尔坎金字塔屹立其中。它的每个面有91级台阶，4个面象征一年四季，共364级台阶，加上塔顶的神殿共365级，象征一年365天。4个边缘分别代表春分、秋分、夏至和冬至。在金字 塔的北面两底角雕有两个蛇头。每年春分、秋分两天，太阳落山时，可以看到蛇头投射在地上的影子与许多个三角形连套在一起，成为一条动感很强的飞蛇。好像从天空中游向大地，栩栩如生。春分蛇由上至下出现，仿佛从神庙中爬出来一样，秋分则由下至上出现，像是爬进去一样。只有每年的这两天里才能看到这一奇景。所以，现在它已经成为墨西哥的一个著名旅游景点。而在当年，玛雅人可以借助这种将天文学与建筑工艺精湛地融合在一起的直观景致，准确把握农时。与此同时，也准确把握崇拜羽蛇神的时机。考古学家在玛雅神庙下方发现神秘的坑洞，进一步的考察发现，坑洞是自然形成的，延伸大约34米，深度为20米 左右。最新的消息指出，神秘下方的洞穴可连接到其他洞穴或者地下湖泊，同时具有深层次的宗教意义，在玛雅文化中处于非常重要的地位。这座寺庙名称为Kukuerkan，即库库尔坎金字塔，这是中美洲最著名的古文明遗址之一，是玛雅文明的巅峰之作。那么金字塔下方的洞穴为何会存在呢，具有何种宗教意义？ 考古学家发现玛雅人在1000年前建造了金字塔，位于一个巨大的天然深坑 上，他们相信建立在深坑顶部的建筑是宗教信仰的一部分，因为库库尔坎金字塔内有一尊玛雅蛇神，或者认为是有羽毛的蛇，它是玛雅人非常崇拜的蛇神。由于蛇神需要水，因此神殿下方是一个被填满水的深坑，水流的运行由北向南。考古学家通过一种新的探测技术对神殿下方的结构进行研究，发现了深坑的存在，探测器能够探测到岩石结构走向，分辨出水流和岩石的相对位置。