Umlando wokudalwa kwethiyori kaHayflick
ULeonard Hayflick (owazalwa ngoMeyi 20, 1928 ePhiladelphia), uprofesa wesayensi yemvelo e-University of California eSan Francisco, wakha inkolelo-mbono yakhe ngenkathi esebenza e-Wistar Institute ePhiladelphia, ePennsylvania, ngo-1965. UFrank MacFarlane Burnet wetha le nkolelo-mbono ngoHayflick incwadi yakhe enesihloko esithi Internal Mutagenesis, eyanyatheliswa ngo-1974. Umqondo womkhawulo kaHayflick wasiza ososayensi ukuba bahlole imiphumela yokuguga kwamangqamuzana emzimbeni womuntu, ukukhula kwamangqamuzana ukusuka esigabeni sombungu kuya ekufeni, kuhlanganise nomphumela wokunciphisa ubude bamaphethelo ama-chromosome abizwa ngokuthi. ama-telomeres.
Ngo-1961, uHayflick waqala ukusebenza e-Wistar Institute, lapho abona khona ngokubona ukuthi amangqamuzana omuntu awahlukani unomphela. U-Hayflick kanye no-Paul Moorehead bachaze lesi sigameko ku-monograph enesihloko esithi Serial Cultivation of Human Diploid Cell Strains. Umsebenzi kaHayflick e-Wistar Institute wawuhloselwe ukunikeza isisombululo somsoco kososayensi abenza izivivinyo kulesi sikhungo, kodwa ngesikhathi esifanayo uHayflick wayezibandakanye ocwaningweni lwakhe ngemiphumela yamagciwane kumaseli. Ngo-1965, uHayflick wachaza kabanzi ngomqondo womkhawulo we-Hayflick ku-monograph enesihloko esithi "Limited Lifespan of Human Diploid Cell Strains in the Artificial Environment".
UHayflick wafinyelela esiphethweni sokuthi ingqamuzana liyakwazi ukuqeda i-mitosis, okungukuthi, inqubo yokukhiqiza kabusha ngokuhlukana, izikhathi ezingamashumi amane kuya kwezingamashumi ayisithupha kuphela, ngemva kwalokho ukufa kwenzeka. Lesi siphetho sasisebenza kuzo zonke izinhlobo zamangqamuzana, kungakhathaliseki ukuthi amangqamuzana amadala noma amagciwane. U-Hayflick wabeka phambili umbono wokuthi ikhono elincane lokuphindaphinda leseli lihlotshaniswa nokuguga kwalo futhi, ngokufanele, nenqubo yokuguga yomzimba womuntu.
Ngo-1974, uHayflick wasungula iNational Institute on Aging eBethesda, eMaryland.
Lesi sikhungo siyingxenye ye-US National Institutes of Health. Ngo-1982, uHayflick uphinde waba yiphini likasihlalo we-American Society for Gerontology, eyasungulwa ngo-1945 eNew York. Kamuva, uHayflick wasebenzela ukukhulisa umbono wakhe futhi aphikise umbono kaCarrel wokungafi kwamaselula.
Ukuphikiswa kwethiyori kaCarrel
U-Alexis Carrel, udokotela ohlinzayo ongumFulentshi owayesebenza ngezicubu zenhliziyo yenkukhu ekuqaleni kwekhulu lamashumi amabili, wayekholelwa ukuthi amangqamuzana angazalana unomphela ngokuhlukana. UCarrel wathi wakwazi ukufeza ukuhlukaniswa kwamangqamuzana enhliziyo yenkukhu endaweni enomsoco - le nqubo yaqhubeka iminyaka engaphezu kwamashumi amabili. Ukuhlola kwakhe izicubu zenhliziyo yenkukhu kwaqinisa inkolelo-mbono yokuhlukana kwamangqamuzana okungapheli. Ososayensi baye bazama kaningi ukuphinda umsebenzi kaCarrel, kodwa ukuhlola kwabo akuzange kuqinisekise "ukutholwa" kukaCarrel.
Ukugxekwa kwethiyori kaHayflick
Ngawo-1990, abanye ososayensi, abanjengoHarry Rubin eNyuvesi yaseCalifornia eBerkeley, bathi umkhawulo weHayflick usebenza kuphela kumaseli alimele. U-Rubin uphakamise ukuthi ukulimala kwamangqamuzana kungabangelwa amaseli ukuba sendaweni ehlukile endaweni yawo yasekuqaleni emzimbeni, noma ngososayensi abadalula amaseli elebhu.
Ucwaningo olwengeziwe mayelana nokwenzeka kokuguga
Naphezu kokugxekwa, abanye ososayensi baye basebenzisa inkolelo-mbono kaHayflick njengesisekelo socwaningo olwengeziwe mayelana nesenzakalo sokuguga kwamangqamuzana, ikakhulukazi ama-telomere, okuyizingxenye zokugcina zama-chromosome. Ama-telomere avikela ama-chromosome futhi anciphise ukuguqulwa kwe-DNA. Ngo-1973, usosayensi waseRussia u-A. Olovnikov wasebenzisa inkolelo-mbono ka-Hayflick yokufa kwamangqamuzana ezifundweni zakhe zokuphela kwama-chromosome angazizali ngesikhathi se-mitosis. Ngokuka-Olovnikov, inqubo yokuhlukaniswa kwamangqamuzana iphela ngokushesha lapho ingqamuzana lingasakwazi ukukhiqiza iziphetho zama-chromosome alo.
Ngemva konyaka, ngo-1974, uBurnet wabiza ithiyori kaHayflick ngokuthi umkhawulo weHayflick, esebenzisa leli gama ephepheni lakhe elithi, Internal Mutagenesis. Umnyombo womsebenzi kaBurnet kwakuwukucabanga ukuthi ukuguga kuyisici esiyisisekelo esitholakala kumaseli ezinhlobo ezihlukahlukene zokuphila, nokuthi umsebenzi wawo obalulekile uhambisana nethiyori eyaziwa ngokuthi umkhawulo weHayflick, osungula isikhathi sokufa kwento ephilayo.
U-Elizabeth Blackburn waseNyuvesi yaseSan Francisco kanye nozakwabo uJack Szostak waseHarvard Medical School eBoston, Massachusetts, baphendukela emfundisweni yomkhawulo kaHayflick ezifundweni zabo zesakhiwo sama-telomere ngo-1982 lapho bephumelela ekwenzeni i-cloning nokuhlukanisa ama-telomere.
Ngo-1989, uGreider noBlackburn bathatha isinyathelo esilandelayo sokutadisha isenzakalo sokuguga kwamangqamuzana ngokuthola i-enzyme ebizwa ngokuthi i-telomerase (i-enzyme evela eqenjini lokudlulisa elilawula usayizi, inombolo kanye nokwakheka kwe-nucleotide ye-chromosome telomeres). UGreider noBlackburn bathola ukuthi ukuba khona kwe-telomerase kusiza amangqamuzana omzimba agweme ukufa okuhleliwe.
Ngo-2009, uBlackburn, D. Szostak kanye no-K. Greider bathola uMklomelo KaNobel kuPhysiology noma Medicine namagama athi “ngokuthola kwabo izindlela zokuvikela ama-chromosome ngama-telomere kanye ne-enzyme telomerase.” Ucwaningo lwabo belusekelwe kumkhawulo we-Hayflick.