Apr. 5, 1999 Researchers at UC San Francisco have determined
that telomerase - the enzyme brought to fame last year when
scientists demonstrated that its insertion into normal cells
extended the healthy life span of the cells indefinitely - can
wield its power in an unexpected way. The finding, reported in
the current issue of Proceedings of the National Academy of
Sciences, could bolster efforts aimed at manipulating the enzyme
for therapeutic purposes - whether to prompt cell division in
order to replenish stocks of healthy cells, as is needed in bone
marrow transplants, or to interrupt the excessive cell
proliferation that occurs in cancer cells. Telomerase
synthesizes telomeres, snippets of DNA on the ends of
chromosomes that function in part like the plastic tips on the
ends of shoelaces, preventing the gene-bearing, threadlike
spindles from unraveling. With each cycle of cell division, the
tips of telomeres drop off, until the chemical bookends become
so eroded that the chromosomes become unstable, a co