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1、IELTSADVANTAGETrue/False/NGQuestionsStrategyPracticeHowhumanmedicinecouldsavetheTasmaniandevilTransmissiblecancersareincrediblyrareinnature,yethaveariseninTasmaniandevils(atypicallydog-sizedmammalwhichlivesinthewildonlyontheAustralianislandofTasmania)onatleasttwoseparateoccasions.NewresearchfromtheU
2、niversityofCambridgehasidentifiedkeyanti-cancerdrugswhichcouldbetrialledasatreatmentforthesediseases,whicharethreateningTasmaniandevilswithextinction.TheresearchalsofoundthatthetwoTasmaniandeviltransmissiblecancersareverysimilartoeachother,andlikelybotharoseduetosusceptibilitiesinherenttothedevilsth
3、emselves.Tasmaniandevilsareconsideredendangeredduetodevilfacialtumour1(DFT1),acancerthatispassedbetweenanimalsthroughthetransferoflivingcancercellswhentheanimalsbiteeachother.DFT1causesgrotesqueanddisfiguringfacialtumourswhichusuallyMilaffectedindividuals.TheDFT1cancerfirstaroseinasingleindividualde
4、vilseveraldecadesago,butratherthandyingtogetherwiththisdevil,thecancersurvivedby4metastasising,intodifferentdevils.Therefore,theDNAofthedevils,tumourcellsisnottheirownDNA,butratherbelongstotheindividualdevilthatfirstgaverisetoDFT1allthoseyearsago.Remarkably,DFT1cellscanescapethedevils*immunesystemsd
5、espitebeinginessenceaforeignbody.TheDFT1cancerwasfirstobservedinnorth-eastTasmaniain1996,buthassubsequentlyspreadwidelythroughouttheisland,causingsignificantdeclinesindevilpopulations.In2014,routinediagnosticscreeningrevealedasecondtransmissiblecancerinTasmaniandevils,devilfacialtumour2(DFT2),whichc
6、ausesfacialtumoursindistinguishabletothenakedeyefromthosecausedbyDFT1,andwhichisprobablyalsospreadbybiting.However,analysisshowedthatthetwotypesofcancerdifferatabiologicallevel,andwhereasDFT1firstarosefromthecellsofafemaledevil,DFT2appearstohavefirstarisenfromamaleanimal.Fornow,DFT2appearstobeconfin
7、edtoapeninsulainTasmania,ssouth-east.uThediscoveryofasecondtransmissiblecancerinTasmaniandevilswasahugesurprise,saysDrElizabethMurchisonfromtheDepartmentofVeterinaryMedicineattheUniversityofCambridge.uOtherthanthesetwocancers,weknowofonlyoneothernaturallyoccurringtransmissiblecancerinmammals-thecani
8、netransmissiblevenerealtumourindogs,whichfirstemergedseveralthousandyearsago.Note:ThisisnotarealIELTStest.Thispracticetestistogiveyouanopportunitytopractiseimplementingthestrategiesfromthecourse.Itdoesnotreflectthescores,timeneededorlevelofdifficultyofarealIELTStest.IELTSADVANTAGETrue/False/NGQuesti
9、onsStrategyPracticeInfact,outsideofmammals,onlyfivetransmissiblecancershavebeenobserved,allofwhichcauseIeukaemia-Iikediseasesinclamsandothershellfish.“Thescarcityoftransmissiblecancerssuggeststhatsuchdiseasesemergerarely,sheadds.Before1996,noonehadobservedtheminTasmaniandevils,sofindingtwotransmissi
10、blecancersinTasmaniandevilsinjusteighteenyearswasverysurprising?Inordertoseewhetherthedeviltransmissiblecancersarecausedbyexternalfactorsorwhethertheanimalswerejustparticularlysusceptibletodevelopingthesecancers,aresearchteamledbyDrMurchisonanalysedthegeneticprofilesofDFT1andDFT2tumourstakenfromanum
11、berofTasmaniandevils.Theteamfoundstrikingsimilaritiesintissues-of-origin,genetics,howthecancercellsmutate,andpossibledrugtargets.Thisimpliesthatthetwotumoursbelongtothesamecancertypeandaroseviasimilarmechanisms.Theteamstudiedthegeneticandphysicalfeaturesofthetumours,andcomparedthetwolineageswitheach
12、otherandwithhumancancers.Indoingso,theyidentifiedanimportantroleinthetumoursforparticulartypesofmoleculesknownasreceptortyrosinekinases(RTKs)insustaininggrowthandsurvivalofDFTcancers.Importantly,drugstargetingRTKshavealreadybeendevelopedforhumancancer,andtheresearchersshowedthatthesedrugsefficiently
13、stoppedthegrowthofdevilcancercellsgrowinginthelab.ThisleadstohopethatitmaybepossibletousethesedrugstohelpTasmaniandevils.WhyTasmaniandevilsshouldbeparticularlysusceptibletotheemergenceofDFTsisnotclear.However,devilsbiteeachotherfrequentlyaroundthefacialarea,oftencausingsignificanttissueinjury.Givent
14、heimportantroleforRTKmoleculesinwoundhealing,theresearchersspeculatethatDFTcancersmayarisefromerrorsinthemaintenanceofproliferativecellsinvolvedintissuerepairafterinjury.Whenfighting,Tasmaniandevilsoftenbitetheiropponentsface,whichmaypredisposetheseanimalstotheemergenceofthisparticulartypeofcancervi
15、atissueinjury,saysfirstauthorofthestudy,MaximilianStammnitz.uAsbitingoccursontheface,thiswouldsimultaneouslyprovidearouteofcelltransmission.,TheresearcherssayitisalsopossiblethathumanactivitiesmayhaveindirectlyincreasedtheriskoftheemergenceorspreadoftransmissibledevilfacialtumoursNote:Thisisnotareal
16、IELTStest.Thispracticetestistogiveyouanopportunitytopractiseimplementingthestrategiesfromthecourse.Itdoesnotreflectthescores,timeneededorlevelofdifficultyofarealIELTStest.IELTSADVANTAGETrue/False/NGQuestionsStrategyPractice(DFTs)inrecentyears.Forinstance,itispossiblethatsomemodernlandusepracticesmayhaveprovidedfavourableconditionsfordevils,leadingtoanincreaseinlocalpopulationdensitiesofdevils,andtogreatercompetition,interactionsand
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