TELOMERASE ACTIVITY IN IMMORTAL FISH

Eukaryotic chromosome termini consist of telomeres, short sequence rep eats. According to the telomere hypothesis, DNA replication leads to t elomere shortening, resulting in a cellular mitotic clock. Telomerase resets it by telomere synthesis. In mammals with a limited growth phas e, telomerase activity in somatic tissues is restricted to stem cell d erivatives with high proliferation potential. But other animals, like some fish, grow throughout their life with little senescence, All soma tic cells require a high proliferation capacity and telomerase should be active in all cells, irrespective of fish age. Indeed, we detected high telomerase activities in all analyzed organs of rainbow trout (On corhynchus mykiss). (C) 1998 Federation of European Biochemical Societ ies.