Abstract
Birds are unique models for molecular studies on aging processes and cellular senescence because of their slow rates of aging and comparatively long life spans among homoeothermic animals. The study aimed to examine the relative telomere length and amount of nuclear, mitochondrial DNA lesions in hens of different ages and to find out the correlation between these biomarkers of aging. The study was carried out on hens of crossbreed «High Sex Brown» of different age groups - 1, 75, 225, 330, 450 days old. The measurements of telomeres and DNA damage were done in red cells of hens using quantitative PCR technique. We found out that the amount of telomeric DNA reduced significantly with age. Telomere length ratio to control group (1 day old) made up: 0.88±0.08 for 75 days old, 0.73±0.07 for 225 days old, 0.66±0.1 for 330-days old and 0.58±0.12 for 450 days old. The amount of DNA lesions in both genomes had great, age-dependent increase. The relative quantity of lesions per 10 kb detected in the nuclear DNA were as follows: 0.17±0.19 for 75 days old, 0.66±0.21 for 225 days old, 1.02±0.33 for 330-days old and 1.48±0.45 for 450 days old and the relative quantity of lesions in mtDNA were as follows: 0.11±0.06 for 75 days old, 0.84±0.23 for 225 days old, 1.18±0.3 for 330-days old and 1.49±0.35 for 450 days old. The results obtained are of fundamental interest for aging processes, as well as could have an economic value for poultry farming.
Highlights
The aging processes are being widely investigated in diverse taxa (Gomes et al, 2010; Baudisch, 2012) and among vertebrates aging of birds is of particular interest
It has been found that telomere length of somatic cells decreases with age in various species of different taxa, for instance: Siberian sturgeon (Simide et al, 2016), turquoise killifish (Ocalewicz, 2013), nine-spine stickleback (Noreikiene et al, 2017), loggerhead sea turtle (Hatase et al, 2008), alligators (Scott et al, 2006; Xu et al, 2009) sand martins, dunlins (Pauliny et al, 2006), donkey, sheep, domestic cat (Gomes et al, 2010) and others
The results of telomere length measurement by qPCR revealed the correlation between birds age and relative telomere length. dCt (Ct Tel-Ct Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)) values were as follows: 1 day old 7.5±0.4; 75 days old 6.6±0.7; 225 days old 5.5±0.5; 330-days old 4.9±0.7; 450 days old 4.3±0.9
Summary
The aging processes are being widely investigated in diverse taxa (Gomes et al, 2010; Baudisch, 2012) and among vertebrates aging of birds is of particular interest. Birds have the paradoxical long life expectancy and slow rates of aging as compare with mammals, especially, taking into account such features of avian physiology, that adversely affect lifespan: elevated body temperature (about 3°C higher than in mammals), rapid metabolism processes (2-2.5 times higher), high blood glucose content (2-4 times higher) (Holmes et al, 2001; Austad, 2011). All these features make birds extremely interesting objects for studying the aging processes. Telomeres length has high interindividual variability and depends on many genetic and environmental factors
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