>Divergent Model of Aging? Negligible Senescence in Long-Lived Fishes
>(John C. Guerin, San Diego, CA).
>
>Like mammals, fish display patterns of rapid and gradual senescence, such
>as the Pacific salmon and Medaka, respectively. But unlike warm-blooded
>animals, some poikilotherms exhibit negligible senescence, which is
>chronological aging without an increase in mortality rate. Leonard
>Hayflick observed that "If they do age, it occurs at such a slow rate
>that their aging has not been demonstrated convincingly", and he felt
>this phenomenon was important to study (from his book "How and Why We
>Age", 1994, and personal communication Nov. 1995).
>
>Since fish with gradual senescence exhibit a decline in reproductive
>capacity, oxidative metabolism, protein utilisation and cell numbers
>(neurons), with an increase in mortality rate, cross-linking, lipofuscin,
>and lipid peroxidation, the lowered metabolism of cold-blooded animals alone
>can't be the answer. Perhaps then, the "information derived on the
>mechanism causing extended longevity in such species might be useful in
>finding clues for life extension strategies in humans" (quote and
>information in this paragraph from "Ageing in Cold-Blooded Vertebrates",
>guest editor B.K. Patnaik, International Journal of Experimental and
>Clinical Gerontology, V40, 1994).
>
>A sixty year old halibut was found still fertile and growing upon its
>capture, a rougheye rockfish was recorded at 140 years old, and sturgeon
>are documented at over 150 years old (compiled by Caleb Finch,
>"Longevity, Senescence and the Genome", 1990). In rockfish studied for
>fifteen years by Victoria O'Connell, Alaska Fish and Game, ages ranged up
>to 118 years old, with only three having been reproductively senescent
>during that time (personal communication Mar. 1996). In a recreational book
>on raising Koi in Japan, a record koi was reported to be 222 years old in
>1973, determined by counting scale rings by electron microscope.
>Numerous koi are said to be 100-200 years in age, outliving their owners
>(Nishikigoi Fancy Koi, by Takehiko Tamaki 1974).
>
>Do these long-lived fishes offer a divergent model of senescence? Could
>we look at two closely related species of fish with very different
>patterns of senescence, and examine genetic, hormonal and environmental
>regulators? Would altering certain genetic alleles then alter the
>pattern of negligible senescence in long-lived fishes?
>
>If you are interested in working with this project, have ideas or would
>like additional information, contact John C. Guerin at e-mail address
>ba182 at lafn.org, or call me at (619) 563-9473.
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>John C. Guerin