PAITZ, R.T.; HAUSSMANN, M.F.; BOWDEN, R.M.; JANZEN, F.J.; VLECK, C.M.; Illinois State Univ.; Iowa State Univ.; Illinois State Univ.; Iowa State Univ.; Iowa State Univ.: Long telomeres may minimize the effect of aging in the painted turtle

Nearly all organisms show evidence of aging, involving progressive loss of physiological functioning and increasing risk of death. Telomeres are short tandem sequences of DNA located at the ends of eukaryotic chromosomes. Telomere restriction fragments (TRF) are normally detected between 5-35 kb in birds and mammals, and in non-germline tissues shorten with age in many taxa. During normal aging, the gradual loss of telomeric DNA can contribute to cellular senescence, and has generated interest in whether telomere shortening is involved in increased age-related disease and mortality. We examined telomeres in a long-lived vertebrate, the painted turtle (Chrysemys picta), to assess age-related variation in telomere length. Painted turtles continue to grow throughout their lives (estimated at >60 years) and the reproductive output of older females is comparable to or exceeds that of younger females with no apparent age-related decline in reproductive viability. We extracted DNA from blood cells collected from turtles of five different age classes: hatchling (<10 d), juvenile (2 yr), immature (3-5 yr), young mature (6-10 yr), and old mature (>12 yr). Mean TRF length was measured by separating digested DNA in a pulsed-field electrophoresis system. We did not detect any age-related variation in TRF length (p > 0.05), nor did we observe any TRFs shorter than ~60kb, sizes which are common in previously studied taxa. If turtles do not have TRFs shorter than 60kb, cellular senescence caused by telomere shortening may not apply to turtles. These long telomeres could potentially explain the indeterminate growth and apparent lack of reproductive senescence characteristic of painted turtles.