An kammala cikakken jerin kwayoyin halittar ɗan adam na chromosomes guda biyu na X da autosomes daga layin ƙwayar halittar mace da aka samo. Wannan ya haɗa da kashi 8% na jerin kwayoyin halittar da ya ɓace a cikin daftarin farko da aka fitar a shekara ta 2001.
An bayyana cikakken jerin kwayoyin halittar ɗan adam na dukkan nau'ikan tushen biliyan 3.055 ta hanyar ƙungiyar Telomere-to-Telomere (T2T). Wannan yana wakiltar mafi girman ci gaba ga kwayar halittar ɗan adam da aka fitar a shekara ta 2001 ta Celera Genomics da International Human Genome Sequencing Consortium. Wannan jerin kwayoyin halittar ya rufe yawancin yankunan euchromatic yayin da ko dai ya bar yankunan heterochromatin ko kuma wakilcin da ba daidai ba. Waɗannan yankuna sun ƙunshi kashi 8% na kwayar halittar ɗan adam da aka bayyana a ƙarshe. Sabon bayanin T2T-CHM13 1 ya haɗa da cikakken jerin dukkan autosomes 22 tare da Chromosome X. Wannan sabon jerin ya kuma gyara kurakurai da yawa, kuma ya ƙara kusan bp miliyan 200 na sabbin jerin da ke ɗauke da kwafin kwayoyin halitta 2,226, daga cikinsu ana hasashen 115 za su kasance suna da lambar sunadaran.
Tsarin halittar GRCh38.p13 na yanzu ya kasance sakamakon manyan sabuntawa guda biyu, ɗaya a cikin 2013 da ɗayan kuma a cikin 2019 akan jerin kwayoyin halittar Celera na 2001. Duk da haka, har yanzu yana da nau'ikan tushe miliyan 151 na jerin da ba a san su ba da aka rarraba a cikin kwayar halittar , gami da yankunan pericentromeric da sub telomeric, kwafi, jerin kwayoyin halitta da ribosomal DNA (rDNA), duk waɗannan suna da mahimmanci don hanyoyin ƙwayoyin halitta na asali. An sanya wa sabon bayanin suna a matsayin T2T-CHM13 saboda ya fito ne daga jerin DNA daga layin ƙwayoyin halittar CHM13 (Complete Hydatiform Mole) kuma ƙungiyar T2T ce ke yin sa. Layin ƙwayar halitta ya samo asali ne daga ƙwai da aka haɗu da ba daidai ba ko kuma yawan ƙwayar nama daga mahaifa inda mata ke da juna biyu (cikin ciki na ƙarya), don haka jerin suna wakiltar kawai chromosomes X guda biyu da autosomes na mace. An yi amfani da fasahohin jerin abubuwa da yawa kamar PacBio, Oxford Nanopore, 100X da 70X Illumina sequencers don ambato kaɗan. Ci gaban fasaha a jerin abubuwa ya haifar da jerin sauran kashi 8% kamar yadda aka ambata a sama.
Iyakance kawai na jerin T2T-CHM13 shine rashin chromosome Y. Ana ci gaba da wannan jeri a halin yanzu, ta amfani da DNA daga layin salula na HG002, wanda ke da 46 (biyu 23) tare da karyotype XY. Daga nan za a haɗa jerin abubuwan ta amfani da hanyoyin da aka ƙera don homozygous CHM13 genome.
Samuwar T2T-CHM13 a matsayin sabon kwayar halittar da aka yi amfani da ita wajen tantance kwayoyin halitta yana wakiltar babban ci gaba wanda zai taimaka wajen fahimtar rawar da yankunan heterochromatin ke takawa da kuma taimakawa wajen fahimtar tasirinsa akan hanyoyin tantanin halitta dalla-dalla. Har sai an kammala jerin kwayoyin halittar Y, wannan zai zama kwayar halittar da aka yi amfani da ita don nazarin gaba wajen fahimtar hanyoyin tantanin halitta da ayyukanta.
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References
- Nurk S, Koren S, Rhie A, Rautiainen M, Bzikadze AV, Mikheenko A et al. Cikakken jerin a mutum kwayoyin halitta bioRxiv 2021.05.26.445798; DOI: https://doi.org/10.1101/2021.05.26.445798
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