Effect of storage temperature and duration on direct PCR amplification of various feather types and DBS matrices

The use of direct PCR has been pioneered over the last decade for DNA analysis of biological specimens of distinct origins. The information on how longer these specimens can be stored and amplified by direct PCR is however scanty. Such a piece of information could expedite research and diagnostic studies without compromising the reliability of results. The current study was therefore designed to analyze the effect of storage temperature and duration on direct PCR amplification of biological specimens having either low quantity or high quantity of DNA. Whole blood, dried blood spots (DBS), and feathers from chicken were stored for five years at three different temperatures, viz. room temperature (∼25 °C), 4 °C, and -20 °C. These samples were subjected to crude DNA extraction by diluting them in PBS buffer and heating at 98 °C after 1 day, 7 days, 15 days, 1 month, 3 months, 6 months, 1 year, 3 years and 5 years of storage. The crude DNA was PCR-amplified with the use of DNA sexing primers as well as DNA barcoding primers. Incubation at 98 °C for 10 min of any type of sample in PBS buffer was sufficient for crude DNA extraction. There was irrelevant impact of feather type, DBS matrix nature and storage temperature on amplification success over the period of analysis. It was possible to successfully accomplish the amplification of 96 samples with the use of routine PCR reagents within 3.5-6.0 hrs. In short, economical and fast genetic analysis of commonly used avian samples is feasible after their storage for longer time at room temperature.