The reduced DNA stability at RH

The reduced DNA stability at 100% RH confirms previous results for incubates at these conditions, although in the present study amplifiable DNA still survived for months. The crucial point appears to be the onset of microbial growth, which happened at room temperature and at 35 °C. In the biologically less favourable temperature range (45–65 °C) microbial growth was not observed, but DNA was evidently less stable since the amplificability of the 1600bp and 273bp fragments dropped to approximately one month, and three months, respectively, at 55 °C and 65 °C. It is, however, noted that even at 45 °C, the 1600bp fragment was amplifiable after eight months. Given the high stability of DNA in dry stains at ambient temperature and humidity, it can be excluded that endogenic RVX-208 play any significant role in the degradation of DNA. Firstly, the low quantity of water in “dry” stains presumably is too small to allow enzymatic reactions to occur, secondly, most endogenic enzymes become inactivated due to denaturation during the drying process. The present results indicate that degradation of DNA at lower temperatures is mainly exerted by the presence of microbial organisms. At higher temperatures (in the present work 45–65 °C), degradation of DNA is probably the result of spontaneous hydrolytic and oxidative reactions, most notably depurination which results in subsequent breakage of the DNA strand. Such non-enzymatic reactions are often more temperature sensitive than enzymatic processes; for example the rate of depurination increases 6–7 fold for each 10 °C the temperature is raised, as compared to ∼2 fold for enzymatic reactions.26, 27, 28 The result of these non-enzymatic reactions is the accumulation of nucleotide derivatives that affect the ability to PCR amplify the DNA, as well as an exponential increase in shorter and shorter DNA fragments.11, 29, 30 The present work shows that normal climatic conditions are not critical for the long time survival of DNA in untreated blood stains. This information may be useful for laboratories who wish to store reference blood samples in a simple way, while saving the costs of commercial substrates that are treated with DNA stabilizing agents. The amplicon size of standard forensic STR’s are <500bp, and <300bp for STRs tailored for degraded DNA (e.g., Minifiler®, Applied Biosystems, Foster City, CA), and for SNP-based systems the amplicon size is <150 bp. We believe that the present findings, using a 1600bp fragment that is much larger than any STR amplicon, and a 245bp fragment larger than any SNP amplicon, provide an adequate assessment of the forensic applicability of DNA after long time storage of blood stains.
Introduction Performance in poultry breeding flocks, routinely measured by fertility and hatchability of eggs, is dependent on genetic and non-genetic components related to males and females, as well as the synergy of these two components (Wolc et al., 2009). These contributions of both sexes to egg fertilization and embryo development enhance the need for selection of females and males simultaneously (Wolc et al., 2009). In males, reproductive efficiency may be affected by behavioral and semen variables, which seemingly have low and moderate-to-high heritability, respectively (Soller et al., 1965, Dunnington and Siegel, 1983, Ansah et al., 1985, Barbato, 1999, Kabir et al., 2007, Hu et al., 2013). Semen analysis in poultry breeding programs is, therefore, considered a useful technique, not only for sire selection (i.e., prior establishment of the breeding flock), but also for monitoring adult males throughout chick production (Donoghue, 1999, Parker and McDaniel, 2002).