Fig. 1

Different zebrafish tissues have different telomere lengths and follow specific dynamics of shortening with aging.

A) Representative images of telomere restriction fragment (TRF) analysis of genomic DNA by Southern Blot (random primer-labelled telomeric probe (TTAGGG)n ³²P-dCTP). Aa) WT telomeres are longer in whole larvae (“L”, ca. 12 kb) and shorter in 3 month-old zebrafish gut (G), testis (T) and muscle (M), but show significant variation in length between tissues (shown for two independent WT zebrafish “1” and “2” in Fig 1Aa, except for testis where only zebrafish “1” is shown; densitometry shown for zebrafish “1”, Fig 1Ab). WT have longer telomeres in testis (ca.9.9 Kb), followed by muscle (ca. 9.4 Kb) and, finally, gut (8.4 Kb). These differences are globally maintained in tert^-/- tissues (ca. 8.3 Kb in the testis, ca. 8.5 in the muscle and ca. 7.8 Kb in the gut; shown for two 3-month old zebrafish “1” and “2” in Fig 1Aa; densitometry shown for individual “1”, Fig 1Ab). Yellow line indicates median telomere length, mTL, for each tissue sample/lane. B) WT telomeres significantly shorten in the fin and kidney marrow with age, but follow different shortening kinetics with time (black star represents WT larvae telomeres; two zebrafish shown for each age after sexual maturation– 3, 12, 17, 24, 28, 36 months for the fin and 3, 18, 24, 36 months for the kidney marrow). Ba) The telomere shortening rate within the same individual (measured by cutting different fins in different time points) is of 45 bp/month and 90 bp/month for two independent zebrafish (in Fig Ba, lanes 1 and 2 of each time point are the same individual over time between the ages of 3 and 24 months). WT telomeres in the fin match the shorter length of 12-month old tert^-/- mutants by 18–24 months (N = 4 for WT and N = 3 for tert^-/- fin; red star represents tert^-/- larvae telomeres; Fig 1Ba), but WT kidney marrow telomeres never reach tert^-/- levels (N = 3–6 per time point for adult WT and N = 3 for adult tert^-/- mutants, Fig 1Bb). TRF mean sizes were calculated as previously described [54]. mTL data is represented as mean +/- SEM.