Blood puncture as a nondestructive sampling tool to obtain DNA in frogs: comparison of protocols and survival analysis

In molecular biology studies of Anura, nondestructive methods to obtain genetic material are needed as alternatives to toe clipping. This work evaluates a nondestructive method for sampling DNA from blood puncture, comparing the performance of three different extraction protocols (Qiagen Kit, Salting-out and Chelex). We collected 134 individuals of Eleutherodactylus johnstonei, extracting blood via puncture of the medial vein using commercial-grade glucometer lancets. We extracted 1001880 ng DNA, finding no differences between the extraction protocols. We compared the quality of the resulting DNA through amplification and sequencing of the 16S mitochondrial gene. Amplification was successful for the three extraction protocols, although Chelex showed better performance, making it the most recommendable protocol for extraction of DNA from blood. The resulting sequences corresponded to those registered in the GenBank for this species. Additionally, we found no significant differences in survival or weight change between the individuals that were manipulated and a control group (mean survival 66.7% treated, 62.9% untreated). Data reveal that blood samples obtained by puncture are a convenient alternative to other tissues (phalange, buccal swab, liver) that have traditionally been used as DNA sources for anurans. The technique is applicable to small and large species, covering most anuran diversity, provides enough DNA for many genetic applications and produces no noticeable effect on the survival or performance, given that it does not affect the motor parts or the dexterity of the animals.