英语听力英语高级听力材料The Ghost In Your GenesWord格式.docx
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英语听力英语高级听力材料The Ghost In Your GenesWord格式.docx
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snotsomuchyou'
rewhatyoueatassomethingyouarewhatyourmotherate,andmaybeyouarewhatyourgrandmotherate.Andifyoutakeourdata,you'
rewhat'
sstressyourgrandmotherorgrandfatherhad.
Itwouldchangethewaywethinkaboutourrelationshipwitheverygeneration.
(it)Makesmefeelclosertomychildren.WhatIexperienced,intermsofenvironmentwillhavesometypeoflegacyinmychildrenandmygrandchildren.
Thescienceofinheritanceisbeingturnedonitshead.
We'
rechangingtheviewofwhatinheritanceis.
ThissmallSwedishtownmayholdtheevidencetolaunchamedicalrevolution.Ö
verkalixlieshuddledontheedgeoftheArcticCircle.Inaccessibleandremote,itwascutofffromtherestoftheworldformostofitshistory.MarcusPembreyhastraveledheretomeethiscolleague,OlovBygren.Theybelievethatthestorylyingburiedinthesegraveyardsmayholdtheprooftotheirradicalideas.
Herewehaveatleast2generations.
Inthesamegrave.
Inthesame...
Thisgroupofpeoplecouldcontributetoreallyaseachangeinthewaywethinkaboutinheritance.
Theyhavecometothischurchyardtofindgrandmothersandgranddaughters,grandfathersandgrandsons,connectingpeoplewholivedalmostahundredyearsapartinentirelynewways,uncoveringlinksthatconfoundscientificthinking.
Uptonow,inheritanceisjustthegenes,theDNAsequence.Isuspectthatwe'
regonnabeabletodemonstratethattheinheritanceismorethanthat.
Thisisagrandson,asitwere,inourstudy.
Itistheculminationofmorethantwentyyears'
workandforthefirsttime,Pembreyisconfrontingthemagnitudeoftheirdiscovery.
Itreallyhascomealiveforme,comingheremorethanIhadexpected.It'
sreallyquiteso,I'
m,sureaboutit,wonderful.
MarcusPembreyisoneofaselectbandofscientists,abandofscientistswhoaredaringtochallengeanorthodoxy.Theybelievethelivesofourparents,grandparents,andevenourgreatgrandparentscandirectlyaffectourwell-being,despiteneverexperiencinganyofthesethingsourselves.Tomany,theseideasareregardedasscientificheresy.
Youcannotpredictwhereimportantdiscoverieswillbe.Theonlythingthatyoucandoistofollowyourinstinct.
Conventionalbiologyhasalwaysbelievedthatourgeneticinheritanceissetinstoneatthemomentofourconception.Atthatinstant,weeachreceiveasetofchromosomesfrombothourmotherandfather.Withinthesechromosomesarethegenes,stripsofcodedDNA,thebasicunitofinheritance.Afterconception,itwasassumedthatourgenesarelockedawayinsideeverycellofthebody,protectedanduntouchedbythewayyoulive.Sowhatyoudoinyourlifemayaffectyou,butyourgenesremainuntainted,unchangedforfuturegenerations.Inclassicgenetics,yourparentsandgrandparentssimplypassontheirgenes.Theexperiencestheyaccumulateinalifetimeareneverinherited,lostforeverasthegenespassuntouchedthroughgenerationaftergeneration.
Thebiologyofinheritancewasareassuringlypureprocess,orsoitseemed.Intheearly80s,MarcusPembreyheadedtheclinicalgeneticsdepartmentatGreatOrmondStreetHospitalforChildren.Hewasfrequentlytreatingfamilieswithunusualgeneticconditions.
Wewereconstantlycomingacrossfamilieswhichdidn'
tfittherules,didn'
tfitanyofthepatternsthatgeneticsweresupposedtofit.Soyouthinkofchromosomeabnormalitiesandyoucheckthechromosomesandtheyarenormal,soyouthenhavetostartimagining,asitwere,youknow,whatmightbeunderlyingthisandyouwerereallydriventotryandworkitoutbecausethefamiliesneededsomehelp.
Themorefamilieshesaw,themoretherulesofinheritanceappearedtobreakdown--diseasesandconditionsthatsimplydidn'
tfitwiththetextbookconventions.Oneconditioninparticularcaughthiseye,Angelmansyndrome.
NamedafterHenryAngelman,thepediatricianwhofirstdescribedAngelmansyndrome.Hereferredtothemashappypuppetchildrenbecauseitdescribed,tosomeextent,thefeatures.Theyhavearatherjerkysortofmovementwhentheyarewalking.Thesechildrenhavenospeech.Theyareseverelyincapacitatedintermsoflearning,butareuncharacteristicallyhappyastheyaresmilingallthetime.
Theconditionwascausedbyageneticfault:
akeysequenceofDNAwasmissing,deletedfromChromosome15.
Thenwecameacrossaparadox:
atthesametime,er,thesamechange,thesamelittledeletionofChromosome15hadbeenclearlyassociatedwithaquitedifferentsyndrome,muchmilderintermsof,er,ofintellectualimpairment,thePrader-Willisyndrome.Thesechildrenarecharacterizedbybeingveryfloppyatbirth,butoncetheystartedeatingproperlyandsoon,theythenhadaninsatiableappetiteandwouldgetvery,verylarge.
WhatPembreysawsimplymadenosense.Hereweretwocompletelydifferentdiseases,AngelmansyndromeandPrader-Willisyndromebeingcausedbyexactlythesamegeneticfault.
Soherewe'
reinabizarresituationreally,howcouldwehaveproposedthatthesamedeletioncouldcausea,adifferentsyndrome?
ItappearedtoPembreyasifthesimpleviewofinheritancewasbeginningtounravel,buthisdoubtswerecontrarytothetideofoptimismsweepingthescientificcommunity.Intheearly1990s,thebiggestprojecteverundertakeninbiologywascaptivatingtheworld.
TheHumanGenomeProjectwillbeseenastheoutstandingachievementinthehistoryofmankind.
TheHumanGenomeProjectwastobethepinnacleofacenturyofworkongenesandgenetics.Itseemedasifthesecretsoflifewereatourfingertips.
Thegeneticblueprintofmankind...
Nothingelse,merelythewholehumangeneticcodeisasetofinstructionstomakeahumanbeing.
HumangenomeislikeaBiblewhereeverythingwaswrittendown.Thehopeandtheexpectationwasthatoncewehadthatbookinfrontofus,andalltheletterswecouldjustreaddownthepages,andwewouldunderstandhowthebodywasputtogether.
Itwouldofferacompleteunderstandingofhumanbiologyatamolecularlevel.Thehopewasthatoncethecodewaswrittendown,scientistscouldfindthegeneticcauseandcureforeverydisease.
Thelistisendless.
Wewerethinkingofgenesinaverymechanicalway.Wewerethinkingofthemjustintermsofthesequenceoftheletterswhenwewereworkingouthowwecouldworkoutwhatalltheletterswereinthebook.
Scientistsestimatedthatthehumangenome,thebookoflife,wouldcontainaround100,000genes.
Andthenwhentheystartedsequencingthey,theyrealizedtheremaybe100,000genes,anditpoppeddownto60,andthenitpoppeddownto50,Imean,andslowlywentdowntoamuchsmallernumber.Infactwefoundoutthatthehumangenomeisprobablynotascomplexanddoesn'
thaveasmanygenesas,asplantsdo.Sothattheymadeusreallyquestionitall.Ifthegenomehaslessgenesinthisspeciesversusthisspecies,andwearemorecomplexpotentially,what'
sgoingonhere?
Now,scientistsestimatethereareprobablylessthan30,000genes.
Webelieved,Ibelievednaivelythatwewouldbeabletofindthegeneticcomponentsofcommondiseases.That'
sproventobeverydifficult.Theideaofone-gene-one-diseasedoesnotexplainitall.
30,000genesdidn'
tappearenoughtoexplainhumancomplexity.Therehadtobesomethingthey'
dmissed.ThefirsthintsofwhatwasmissinglayinthecuriousparadoxofthePrader-WilliandAngelmansyndromes,twoquitedifferentdiseasescausedbyexactlythesamegeneticfault.WhenPembreylookedattheinheritancepatternfortheirconditionshenoticedsomethingevenstranger.
WhatreallymatteredwastheoriginoftheChromosome15thathadthedeletion.IfthedeletionwasontheChromosome15thatthechildhadinheritedfromfatherthenyouhadPrader-Willisyndrome.Whereas,ifthe,er,deletion,er,wasinheritedfromthemother,er,youhadtheAngelmansyndrome.
ItwasacompletesurprisethatthesamemissingstripofDNAcouldcauseonediseasewhenitcamefromthemotherandacompletelydifferentdiseasewhenitcamefromthefather.Itwasasifthegenesknewwheretheycamefrom.
You'
vegotadevelopingfetusmanifestingthiscondition.HowdoestheChromosome15knowwhereitcamefrom?
It,theremusthavebeenatagoranimprintplacedonthatchromosomeduringeithereggorspermformationinthepreviousgenerationto,tosay"
Hi,Icamefrommother,Icamefromfather"
andwearefunctioningdifferently.Sothat'
sthekeythingthatalthoughtheDNAsequenceisthesamethedifferentsetsofgeneswerebeingsilenceddependingonwhetheritcamefromthemotherorfromthefather.
ItshowedthattherewasclearlymoretoinheritancethansimplythecodedsequenceofDNA.
Wethenrealizedthatweweredealingwithwhatisnowknownasgenomicimprinting.Whatgenomicimprintingmeansis,inanutshell,thatgeneshaveamemoryofwheretheycamefrom.
SomethingotherthanjusttheDNAwascapableofmovingbetweengenerations.Itwasatantalizingglimpseintothisunknownandunexpectedworld.Ahiddenlayeractingonandabletodirectlycontrolhowourgenesfunction.Itmeantthatinheritancewasnotsimplyaboutwhichgenesyouinherited,butwhetherthos
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