Izazi zezinto eziphilayo ziye zathola izinqubo zokuguga

Abanye abantu babukeka bebadala kuneminyaka yabo, kanti abanye ababoni. Kungani lokhu kwenzeka? Ososayensi baseChina babike imiphumela yocwaningo olubonisa ukuxhumana kwesakhi sofuzo esithile nokuguga ngaphambi kwesikhathi. Ngenxa yokuba khona kwalesi sakhi sofuzo, i-pigment emnyama ikhiqizwa emzimbeni. Kukholakala ukuthi umjaho waseCaucasia onesikhumba esimhlophe uvele ngenxa yakhe. Ngenxa yalesi sizathu, kuyadingeka ukucabangela ngokuningiliziwe ubudlelwano phakathi kokuguga nokuguqulwa kwezakhamuzi ezimhlophe zaseYurophu.

Abaningi bethu bafuna ukubukeka bebancane kuneminyaka yethu, ngoba siyaqiniseka ukuthi kusebusheni, njengasesibukweni, ukuthi impilo yomuntu ibonakala. Eqinisweni, njengoba kuye kwafakazelwa ucwaningo ososayensi abahlonishwayo baseDenmark nase-UK, iminyaka yangaphandle yomuntu iyasiza ekunqumeni ubude bokuphila kwakhe. Lokhu kuhlobene ngokuqondile nokuba khona kokuhlobana phakathi kobude be-telomere, okuwuphawu lwe-biomolecular, kanye nobudala bangaphandle. Izazi ze-Gerontologists, ezibuye zibizwe ngokuthi ochwepheshe bokuguga emhlabeni wonke, zithi izinqubo ezinquma ushintsho olukhulu ekubukekeni kufanele ziphenywe ngokucophelela. Lokhu kusiza ukuthuthukisa izindlela zakamuva zokuvuselela kabusha. Kodwa namuhla, isikhathi esincane kakhulu nezinsiza kunikezwa ocwaningweni olunjalo.

Muva nje, ucwaningo olukhulu lwenziwa iqembu lososayensi baseShayina, baseDashi, baseBrithani nabaseJalimane abangabasebenzi bezikhungo ezinkulu zesayensi. Umgomo wakhe kwakuwukuthola izinhlangano ezibanzi ze-genome ukuze zixhumanise iminyaka yangaphandle nezakhi zofuzo. Ikakhulukazi, lokhu kwakuphathelene nobunzima bokushwabana kobuso. Ukwenza lokhu, ama-genomes abantu asebekhulile abangaba ngu-2000 e-UK ahlolisiswa ngokucophelela. Izihloko zazingabahlanganyeli ocwaningweni lwe-Rotterdam, olwenziwa ukuze kucaciswe izici ezibangela ukuphazamiseka okuthile kubantu asebekhulile. Cishe izigidi ezingu-8 ze-nucleotide polymorphisms eyodwa, noma ama-SNP nje kuphela, ahlolwe ukuze kutholakale ukuthi bukhona yini ubudlelwano obuhlobene nobudala.

Ukubonakala kwe-snip kwenzeka lapho kushintsha ama-nucleotide ezingxenyeni ze-DNA noma ngokuqondile kufuzo. Ngamanye amazwi, kuwukuguqulwa okudala i-allele, noma okuhlukile kofuzo. Ama-alleles ahlukile komunye nomunye ngama-snips ambalwa. Lezi zamuva azinawo umthelela okhethekile kunoma yini, ngoba azikwazi ukuthinta izingxenye ezibaluleke kakhulu ze-DNA. Kulesi simo, ukuguqulwa kungaba yinzuzo noma kuyingozi, okubuye kusebenze ekusheshiseni noma ekunciphiseni ukuguga kwesikhumba ebusweni. Ngakho-ke, umbuzo uphakama wokuthola ukuguqulwa okuthile. Ukuze kutholwe ukuhlobana okudingekayo ku-genome, kwakudingeka kuhlukanise izihloko ngamaqembu ukuze kunqunywe ukushintshwa kwe-nucleotide okukodwa okuhambisana namaqembu athile. Ukwakhiwa kwala maqembu kwenzeka kuye ngokuthi isimo sesikhumba ebusweni babahlanganyeli.

Ukuhunyushwa okukodwa noma ngaphezulu okwenzeka kaningi kufanele kube sezakhini zofuzo ezibhekele iminyaka yangaphandle. Ochwepheshe benze ucwaningo kubantu abangu-2693 ukuthola ama-snips anquma ukuguga kwesikhumba sobuso, ukushintsha kwesimo sobuso nombala wesikhumba, nokuba khona kwemibimbi. Naphezu kweqiniso lokuthi abacwaningi abakwazanga ukunquma ukuhlobana okucacile nemibimbi nobudala, kwatholakala ukuthi ukushintshwa kwe-nucleotide eyodwa kungatholakala ku-MC1R etholakala ku-chromosome yeshumi nesithupha. Kodwa uma sicabangela ubulili neminyaka, khona-ke kukhona ukuhlobana phakathi kwama-alleles alesi sakhi. Bonke abantu banesethi ephindwe kabili yama-chromosome, ngakho-ke kukhona amakhophi amabili ofuzo ngalunye. Ngamanye amazwi, nge-MC1R evamile neguqukayo, umuntu uzobukeka emdala ngonyaka, futhi enamafuzo amabili aguqukayo, ngeminyaka emi-2. Kuyaphawuleka ukuthi isakhi sofuzo esibhekwa njengeguquliwe siyi-allele engakwazi ukukhiqiza iphrotheni evamile.

Ukuze bahlole imiphumela yabo, ososayensi basebenzise ulwazi olumayelana nezakhamuzi zase-Denmark ezingaba ngu-600, oluthathwe emiphumeleni yokuhlola injongo yaso kwakuwukuhlola imibimbi nobudala bangaphandle esithombeni. Ngesikhathi esifanayo, ososayensi baziswa kusengaphambili mayelana neminyaka yezifundo. Njengomphumela, kube nokwenzeka ukusungula ukuhlobana nezifinyezo ezibekwe eduze kakhulu ne-MC1R noma ngokuqondile ngaphakathi kwayo. Lokhu akuzange kumise abacwaningi, futhi banquma okunye ukuhlola ngokubamba iqhaza kwabaseYurophu abangu-1173. Ngesikhathi esifanayo, u-99% wezifundo kwakungabesifazane. Njengangaphambili, iminyaka yayihlotshaniswa ne-MC1R.

Umbuzo ophakamayo: yini ephawuleka kangaka ngofuzo lwe-MC1R? Kuye kwafakazelwa kaningi ukuthi iyakwazi ukufaka ikhodi yohlobo 1 lwe-melanocortin receptor, ehilelekile ekuphenduleni okuthile kokusayina. Ngenxa yalokho, i-eumelanin ikhiqizwa, okuyi-pigment emnyama. Ucwaningo lwangaphambilini luqinisekisile ukuthi u-80% wabantu abanesikhumba esikhanyayo noma izinwele ezibomvu bane-MC1R eshintshile. Ukuba khona kwama-spins kuwo kuthinta ukubukeka kwamabala eminyaka yobudala. Kubuye kwavela ukuthi umbala wesikhumba, ngokwezinga elithile, ungathonya ubuhlobo phakathi kweminyaka yobudala nama-alleles. Lobu budlelwano bugqama kakhulu kulabo abanesikhumba esiphaphathekile. Inhlangano encane kunazo zonke yabonwa kubantu abanesikhumba somnqumo.

Kuyaqapheleka ukuthi i-MC1R ithinta ukubukeka kweminyaka, kungakhathaliseki ukuthi angakanani amabala. Lokhu kubonise ukuthi ukuhlobana kungase kube ngenxa yezinye izici zobuso. Ilanga nalo lingase libe yisici esinqumayo, njengoba ama-allele aguquguqukayo abangela umbala obomvu nophuzi ongakwazi ukuvikela isikhumba emisebeni ye-ultraviolet. Naphezu kwalokhu, akukho ukungabaza ngamandla kasoseshini. Ngokusho kwabacwaningi abaningi, i-MC1R iyakwazi ukusebenzisana nezinye izakhi zofuzo ezibandakanyeka ezinqubweni ze-oxidative nezokuvuvukala. Ucwaningo olwengeziwe luyadingeka ukuze kwembulwe izindlela zamangqamuzana nezamakhemikhali ezinto eziphilayo ezinquma ukuguga kwesikhumba.

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