Field blood preservation and DNA extraction from wild mammals: methods and key factors for biodiversity studies

Studies on public health and wild mammal biodiversity include a genetic component. For blood samples, there must be optimal sample collection conditions since these can affect DNA preservation and extraction. This study evaluated the use of liquid and dry DNA preservation methods and commercial and non-commercial DNA extraction methods on field-collected blood samples. For this, 264 total blood samples were collected from wild mammals. A first group of samples was preserved in guanidine hydrochloride (GuHCl) and DNA was extracted using six commercial kits: Bioline, Norgen, Invitrogen, Promega, and Qiagen, in addition to phenol-chloroform isoamyl alcohol (PC) and guanidine thiocyanate (GIT). Another group of samples was preserved in Whatman® FTA® cards and DNA was extracted with PC and GIT. The extractions with GIT and PC showed the highest values (ng/µL) and variation in DNA concentration, while the commercial kit showed low variation. Sample preservation in Whatman® FTA® cards provided low variation and quantity of the extracted DNA compared with the use of GuHCl. Concerning DNA quality, the commercial kits yielded higher purity, while GIT and PC-based protocols provided highly variable results. Furthermore, the use of GIT and PC yielded a higher amount of DNA, yet, of variable quality. Overall, extraction based on commercial kits and Whatman® FTA® preservation allowed obtaining more standardized DNA qualities and quantities.