2014年秋高中英语 Module 6 Animals in Danger Special new experiment训练 外研版必修5VIP免费

SpecialnewexperimentIt'scutting-edgeandcontroversial.Butthereisanewproofthatthecloningoftheendangeredspeciesjustmightwork.ArareAsiancalfbornonanIowafarmispossibllythefirsthealthyanimalclonedfromtheendangeredspecies.OurPeterStandringhasthestory.Intheheartofthemidwestwheredairyfarmsandcattledominatethelandscape,andanexoticbreedcowhasgoteveryonetalking.ItisarareAsiancalfknownasabanteng(班腾野牛),bornrecentlyinthisIowaresearchfarm."Thecalfisnursingatregularintervals,heisbright,alert.Byallaccounts,hecangetupanddownbyhimselfandweareveryhopefulthathewillgoontoliveanormallife."ThestoryofthisuniqueanimalbeginsinCalifornia,attheSanDiegowildanimalparkbantengbreedingprogram.In1980,anadultmalediedwithoutproducinganyoffspring,soresearchersatthezoofrozesomeofbanteng'sskincells,hopingonedaytoputthemtogooduse.Theywereintothe"FrozenZoo".It'sadeepfreezemenagerie(动物园)ofsomeoftherarestanimalsonearth.3200inall.Theirgeneticinformationispreservedin4tanks,keptat-320℉"Weusedtohaveaposteronthewallinhere,itwassaidthatyoumustcollectthingsforreasonsthatyoudonotyetunderstand.Sowecollectasmanysamplesaspossible,wheneverwecan,andweputtheminhere.Theypotentiallywillstaythereformany,many,manygenerations,2or3hundredyears."Lastyear,thebanteng'sskincellswereremovedfromthe"FrozenZoo"andsenttotheAdvancedCellTechnologyLabinWesternMassachusetts.Thebanteng'sDNAwastransferredintotheeggsofordinarybeefcows;thefertilizedeggswerethenimplantedintoseveralsurrogate（代孕）mothers.WhileScientistsbelievethatthistypeofcross-speciescloningholdsgreatpromise,butitisnotassimpleasitseems.Twoyearsago,AdvancedCellclonedarareAsianoxknownasagaur（亚洲野牛）.Itwashailedasthefirstbirthofclonedendangeredanimal.Thegaurdiedlessthantwodaysafterthebirth.Despitethatsetback,scientistsinsistedthatbirthwasaproof----cloningcouldwork.Now,theirdeterminationandpatiencecouldpayoff.Thelong-termsurvivalofthebabybantengwouldbode（预示）wellforhisandotherendangeredspecieswhosenumberscouldhypotheticallybeboostedbythisbravenewexperiment.