Sperm fertilizing lub qe yog qhov pib ntawm lub neej tshiab. Cov ntaub ntawv keeb kwm ntawm niam thiab txiv, uas khaws cov kab mob hauv lub cev, khi ua ke tom qab fertilization.
Txawm li cas los xij, nyob rau theem pib ntawm lub neej no, DNA tseem nyob hauv lub xeev tsis muaj zog hauv cov nucleus. Txawm hais tias thawj qhov kev faib tawm ntawm zygote cell tshwm sim nrog kev pab ntawm leej niam cov khoom khaws cia hauv lub qe, kev sib txuas ntawm cov khoom embryonic tshiab yog qhov tsim nyog rau kev loj hlob ntxiv ntawm embryo, uas yuav tsum tau raug rau embryonic DNA. Hauv kev tshawb fawb tshiab, Kikue Tachibana thiab nws pab pawg ntawm Max Planck Biochemistry Institute, Lub Tebchaws Yelemees, tau lees paub tias lub ntiaj teb pioneer yam tseem ceeb Nr5a2 tau qhib lub embryonic DNA. Cov txiaj ntsig tau tshaj tawm hauv online thaum Lub Kaum Ib Hlis 24, 2022 hauv Science phau ntawv Journal Science, nrog cov ntawv sau npe "Zygotic genome activation los ntawm totipotency pioneer factor Nr5a2".
Qhov pib ntawm lub neej yog ib txoj kev txaus nyiam hauv biology. Poj niam qe yog fertilized los ntawm lawv fusion nrog txiv neej phev hlwb. Los ntawm thawj lub cell ntawm lub embryo, tag nrho cov kab mob tuaj yeem txhim kho. Dab tsi ntawm cov txheej txheem molecular tshwm sim ntawm DNA ntawm lub qe fertilized uas ua rau nws muaj peev xwm ua rau lub qe fertilized los tsim cov kab mob tshiab? Ua ke, pab pawg Tachibana tau kawm txog qhov teeb meem no siv tus qauv nas.
Nws yog lub npe hu hais tias cov pioneer yam tseem ceeb yuav khi rau cov cheeb tsam tshwj xeeb ntawm cov DNA tsis muaj zog los qhib lawv. Tshawb nrhiav seb cov pioneer yam tseem ceeb hauv zygote hlwb yog dab tsi ntawm txoj kev tshawb no tshiab.
Tachibana tau hais tias, "Cov pab pawg tseem ceeb ntawm txoj kev tshawb fawb tshiab no muaj cov kws tshaj lij hauv embryology, biochemistry, bioinformatics, microscopy, thiab genomics. Ua ke, peb tuaj yeem tshawb pom cov ntsiab lus hauv genome, tshawb pom qhov hloov pauv ntawm Nr5a2, thiab tshawb xyuas nws cov txheej txheem ntawm kev ua. sab hauv thiab sab nraum lub cell."
Totipotency pioneer factor Nr5a2
Tus Pioneer qhov tseem ceeb muaj peev xwm los khi rau cov DNA nruj nruj. Lawv nyob rau ib tsev neeg loj ntawm cov ntaub ntawv transcription. Lawv khi rau cov qauv ua ntu zus ntawm DNA kom sau cov noob kab ke.
Imre Gaspar, thawj tus kws sau ntawv ntawm daim ntawv thiab tus kws tshaj lij ntawm Max Planck Lub Tsev Haujlwm ntawm Biochemistry, piav qhia, "Peb pom cov qauv ua ntu zus rau cov qauv mRNA thaum ntxov uas tsim tawm hauv lub embryo thiab tuaj yeem nrhiav tau ntau yam kab ke motifs. Peb pom muaj nyob ze rau ib leeg, tsim ib lub npe hu ua supermotif (supermotif). Qhov kev tshawb pom tshiab no supermotif zoo li lub npe hu ua SINE B1 keeb thiab muaj kev sib raug zoo heev rau cov ntsiab lus ALU uas tau txais txiaj ntsig zoo hauv tib neeg genome. tseem hu ua 'dhia noob' vim tias lawv tuaj yeem txav los ntawm ib qho chaw hauv genome mus rau lwm qhov ntawm qee theem cellular (xws li lub embryo thaum ntxov).
Nr5a2 khi rau qhov supermotif. Johanna Gassler, thawj tus kws sau ntawv ntawm daim ntawv thiab tus kws kho mob embryologist ntawm Max Planck Biochemical Research Institute, tau hais tias, "Thaum pib, Nr5a2 tau pom nyob rau hauv daim siab. Nyob rau hauv kev loj hlob biology, Nr5a2 paub tias tseem ceeb nyob rau theem tom qab. Nr5a2 tseem ceeb npaum li cas tom qab fertilization yog tsis paub, nyob rau hauv peb thwmsim, peb muaj peev xwm nrhiav tau hais tias ib zaug Nr5a2 raug thaiv, feem ntau embryonic mRNA molecules twb tsis tsim lawm. Qhov no qhia tias Nr5a2 ua lub luag haujlwm tseem ceeb hauv cov theem ntxov tshaj plaws ntawm kev loj hlob ntawm embryonic."
Siv cov txheej txheem biochemical thiab genomic tsis ntev los no, cov kws sau ntawv tau sim seb Nr5a2 ua haujlwm li cas hauv kev txhim kho thaum ntxov. Wataru Kobayashi, thawj tus kws sau ntawv ntawm daim ntawv thiab biochemist ntawm Max Planck lub koom haum rau Biochemistry, tau piav qhia, "Peb tau sim paub tseeb tias Nr5a2 tuaj yeem qhib thaj tsam DNA tsis muaj zog, ua rau ntau thaj tsam DNA muaj rau cov txheej txheem rov qab." Yog li, zygote. genome yog qhib rau ntawm ob-cell theem, thiab lub embryo nws thiaj li loj hlob mus rau hauv ib tug tag nrho dynamic kab mob.
Tachibana tau hais tias, "Nrhiav Nr5a2 yog qhov tseem ceeb ntawm kev ua haujlwm ntawm genome yog ib kauj ruam tseem ceeb rau kev ua tiav kev nkag siab txog kev pib ntawm lub neej. Nws kuj tseem pom tseeb tias yuav tsum muaj lwm tus neeg pab cuam los txheeb xyuas. Txog tam sim no, peb txoj kev tshawb fawb muab lub tswv yim Lub moj khaum uas tuaj yeem piav qhia yuav ua li cas transcriptional activation tshwm sim robustly nyob rau hauv thaum ntxov embryos los xyuas kom meej embryonic txoj kev loj hlob raws li ib tug tsis muaj kab mob.