Dynamics of telomere length in captive Siamese cobra (Naja kaouthia) related to age and sex

Abstract

Telomeres comprise tandem repeated DNA sequences that protect the ends of chromosomes from deterioration or fusion with neighboring chromosomes, and their lengths might vary with sex and age. Here, age‐ and sex‐related telomere lengths in male and female captive Siamese cobras (Naja kaouthia) were investigated using quantitative real‐time polymerase chain reaction based on cross‐sectional data. A negative correlation was shown between telomere length and body size in males but not in females. Age‐related sex differences were also recorded. Juvenile female snakes have shorter telomeres relative to males at up to 5 years of age, while body size also rapidly increases during this period. This suggests that an accelerated increase in telomere length of female cobra results from sex hormone stimulation to telomerase activity, reflecting sexually dimorphic phenotypic traits. This might also result from amplification of telomeric repeats on sex chromosomes. By contrast, female Siamese cobras older than 5 years had longer telomeres than males. Diverse sex hormone levels and oxidative stress parameters between sexes may affect telomere length.

Genome Complexity Reduction High-Throughput Genome Sequencing of Green Iguana (Iguana iguana) Reveal a Paradigm Shift in Understanding Sex-Chromosomal Linkages on Homomorphic X and Y Sex Chromosomes

“…The percentage CV for each sample was calculated by determining the standard deviation (SD) of each technical triplicate C p value for GAPDH (G) and sex-specific primers (S), then dividing by the triplicate mean and multiplying by 100. The intra-assay CV should be less than 10% (Schultheiss and Stanton, 2009;Hanneman et al, 2011;Singchat et al, 2019). In the present study, the intra-assay CVs were 1.6267-3.6803 and 1.9351% for G and S, respectively (Supplementary Table S2).…”

Consequence of Paradigm Shift with Repeat Landscapes in Reptiles: Powerful Facilitators of Chromosomal Rearrangements for Diversity and Evolution

“…Such tandem repeats are highly enriched at telomeres and are considered necessary to maintain genomic stability by protecting telomeric regions from degradation [15,19,45,146,168,169]. Apart from their localization at telomeres, these repeats might be embedded within internal sites to form interstitial telomeric sequences, which have been detected in amniote genomes and are considered to be byproducts of ancestral chromosome fusion [170], and are predominantly co-localized with induced chromosome breakage [171][172][173].…”

Snake W Sex Chromosome: The Shadow of Ancestral Amniote Super-Sex Chromosome

“…Cessation of recombination triggers structural changes, predominantly on the Y or W sex chromosomes, including accumulation of deleterious mutations, degradation of gene content, accumulation of repeats, heterochromatinization, and changes in gene expression [20][21][22][23][24][25][26][27][28][29][30][31][32]. Deleterious mutations might accumulate in the nonrecombining region through Muller's ratchet or genetic drift, causing Y or W genes to lose their function or disappear altogether [33].…”