Telomeres comprise tandem repeats of non-coding DNA that protect the ends of chromosomes from degradation during cell division. Telomeres have been considered in senescence and mortality because they tend to shorten with growth, sex, and age. Here, age-specific telomere length in female and male Siamese cobra (Naja kaouthia) was investigated for possible relation to morphological condition. Measurements of relative telomere length (RTL) were performed on erythrocytes of 80 cobras (29 females and 51 males, age range 3 weeks – 11 years) using quantitative real-time polymerase chain reaction (qPCR). Total length (TTL) and snout-vent length (SVL) of cobras were also examined. Results showed association between age and SVL (female, R2=0.30 and male, R2=0.31), and between age and TTL (R2= 0.28 for both female and male). Two simple regression models between age and RTL were then constructed in accordance with two age groups (A: ≤ 4 years and B: > 4 years). Interestingly, in Group A, increase of telomere length was observed in females (p .05, R2=0.91) but not in males (p=0.62, R2=0.03). By contrast, in Group B, telomere length decreased with age in both sexes (female, R2=0.38 and male, R2=0.21) suggesting that increasing age above 4 years resulted in cobra telomere shortening. No evidence for quadratic or higher-order equations was found for the relationship between RTL and SVL or TTL. Observation with chromosome mapping of telomeric repeat (TTAGGG)n, indicated that the female W chromosome showed degeneration and remarkable (TTAGGG)n amplification, although interstitial telomeric sites were found on autosomes in either sex. This might relate to the increase of telomere length in females. Telomere dynamics may affect the aging process differently in females and males given their divergent reproductive strategies. Further research is required regarding sex chromosome constitution, in particular, the degenerate W chromosome and links to female fitness in snakes
Telomeres comprise tandem repeats of non-coding DNA that protect the ends of chromosomes from degradation during cell division. Telomeres have been considered in senescence and mortality because they tend to shorten with growth, sex, and age. Here, age-specific telomere length in female and male Siamese cobra (Naja kaouthia) was investigated for possible relation to morphological condition. Measurements of relative telomere length (RTL) were performed on erythrocytes of 80 cobras (29 females and 51 males, age range 3 weeks – 11 years) using quantitative real-time polymerase chain reaction (qPCR). Total length (TTL) and snout-vent length (SVL) of cobras were also examined. Results showed association between age and SVL (female, R2=0.30 and male, R2=0.31), and between age and TTL (R2= 0.28 for both female and male). Two simple regression models between age and RTL were then constructed in accordance with two age groups (A: ≤ 4 years and B: > 4 years). Interestingly, in Group A, increase of telomere length was observed in females (p .05, R2=0.91) but not in males (p=0.62, R2=0.03). By contrast, in Group B, telomere length decreased with age in both sexes (female, R2=0.38 and male, R2=0.21) suggesting that increasing age above 4 years resulted in cobra telomere shortening. No evidence for quadratic or higher-order equations was found for the relationship between RTL and SVL or TTL. Observation with chromosome mapping of telomeric repeat (TTAGGG)n, indicated that the female W chromosome showed degeneration and remarkable (TTAGGG)n amplification, although interstitial telomeric sites were found on autosomes in either sex. This might relate to the increase of telomere length in females. Telomere dynamics may affect the aging process differently in females and males give ...
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