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

Abstract

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.

Protective Effect of HER2 Gene Polymorphism rs24537331 in the Outcome of Canine Mammary Tumors

“…The relevance of HER2 expression in CMT is not straightforward, with different studies sometimes reporting contradictory results. A growing body of evidence has demonstrated a remarkable genetic variation of the canine HER2 gene, with several SNPs being documented [ 20 , 21 , 24 , 25 ]. Nonetheless, although SNPs in the human HER2 gene have been associated with the susceptibility, clinical course, and response to treatment of breast cancer disease [ 37 , 38 , 39 ], the knowledge regarding the influence of HER2 SNPs on clinicopathological features and prognosis of CMT is still incomplete.…”

“…A veterinary adaptation of the human Nottingham Prognostic Index (vet-NPI) was also computed [ 30 ]. Veterinary-adapted NPI was computed as vet-NPI = [tumor size (cm) × 0.2] + NHG (1, 2, or 3 respectively for grades I, II, and III) + evidence of vascular invasion/regional lymph node metastases (1 or 2 if absent or present, respectively) [ 25 ].…”

“…Although the presence of the receptor in mammary tissues has been confirmed through immunohistochemical analyses, its functional activity may be altered due to genetic variation. Some authors have recognized that genetic variability of the canine HER2 gene exists and includes amplifications, translocations, and genetic single nucleotide polymorphisms (SNP) [ 20 , 21 , 24 , 25 ]. Although our group did not find an association between SNPs in the canine HER2 gene and the risk for CMT development [ 26 ], more recently, the influence of HER2 SNPs on histotype aggressiveness of CMT was demonstrated [ 12 ].…”