DNA methylation levels in candidate genes associated with chronological age in mammals are not conserved in a long-lived seabird

© 2017 De Paoli-Iseppi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Most seabirds do not have any outward identifiers of their chronological age, so estimation of seabird population age structure generally requires expensive, long-term banding studies. We investigated the potential to use a molecular age biomarker to estimate age in short-tailed shearwaters (Ardenna tenuirostris). We quantified DNA methylation in several A. tenuirostris genes that have shown age-related methylation changes in mammals. In birds ranging from chicks to 21 years of age, bisulphite treated blood and feather DNA was sequenced and methylation levels analysed in 67 CpG sites in 13 target gene regions. From blood samples, five of the top relationships with age were identified in KCNC3 loci (CpG66: R2 = 0.325, p = 0.019). In feather samples ELOVL2 (CpG42: R2 = 0.285, p = 0.00048) and EDARADD (CpG46: R2 = 0.168, p = 0.0067) were also weakly correlated with age. However, the majority of markers had no clear association with age (of 131 comparisons only 12 had a p-value < 0.05) and statistical analysis using a penalised lasso approach did not produce an accurate ageing model. Our data indicate that some age-related signatures identified in orthologous mammalian genes are not conserved in the long-lived short tailed shearwater. Alternative molecular approaches will be required to identify a reliable biomarker of chronological age in these seabirds

Comparison of DNA methods defined in UV-Vis spectrometry with a 2 mm and 10 mm light beam passing through the cuvette

Większość danych pochodzących z piśmiennictwa prezentuje rutynowo dwa parametry dotyczące izolatów DNA, a mianowicie jego stężenie oraz zanieczyszczenie białkami. Bardzo ważnym parametrem często pomijanym w doniesieniach naukowych jest zanieczyszczenie próbek DNA odczynnikami do izolacji. Zanieczyszczenia te mogą hamować działanie polimerazy DNA i enzymów restrykcyjnych. W ocenie spektrofotometrycznej istotne znaczenie ma droga optyczna kuwety, ponieważ przy 10 mm nie zawsze możliwy jest pomiar badanych parametrów DNA. Celem pracy było określenie metodą spektroskopii UV-Vis parametrów DNA wyizolowanego za pomocą dwóch komercyjnych zestawów przy dwóch drogach przechodzenia wiązki światła przez kuwetę (2 mm i 10 mm) oraz względem dwóch różnych prób ślepych, tj. wody i buforu, w którym zostało zawieszone DNA.Most of the data in this literature presents two parameters that routinely isolate DNA, namely its concentration and level of protein contamination. A very important factor that is often overlooked in scientific reports is contamination of DNA samples with isolation reagents. These impurities can inhibit the activity of a DNA polymerase and restriction enzymes. When assessed spectrophotometrically the optical path of the cuvette is of great importance, because at 10 mm, it is not always possible to measure the parameters of DNA. The aim of this study was to determine the method of UV-Vis spectroscopy parameters for the DNA isolate using two commercial kits on two paths passing a beam of light through a cuvette (2 mm and 10 mm) and the two different blind tests of water and a buffer in which the DNA was suspended