X-Message-Number: 25369 From: Date: Tue, 21 Dec 2004 09:43:13 EST Subject: telomeres limit both cancer and extreme lifespan >telomeres appear to play no role in either human skin aging, or bone marrow aging.] Heretic! >Telomerase activity was similar in aged and young epidermis. Yes, but telomerase is expressed only in stem cells, and even there it's not enough to prevent shortening. I just tried to force some BJ fibroblasts to express telomerase in a dish (as a practical joke), and they wouldn't do it even with fetal cow hormones and partial synchronizing in S phase. My TRFs on white blood cells from different-age donors show a very large shortening over time (though the longest old telomeres are longer than the shortest young-cell telomeres; there's a lot of individual variation). Seriously, factors other than telomere shortening are more important before advanced age. Being able to turn off telomerase is more important in the short term (to kill cancers), but eventually you'll need them there telomeres. And I don't say that just because I work in a telomerase lab... Content-Type: text/html; charset="US-ASCII" [ AUTOMATICALLY SKIPPING HTML ENCODING! ] Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=25369