Non‐destructive genetic sampling in fish. An improved method for DNA extraction from fish fins and scales

摘要

In recent years, a great number of vertebrate species have been designated at risk and DNA-based studies on threatened or endangered species have been one of the major interests in gathering information on the diversity, conservation biology and population analyses (O'Brien 1994; Avise 1996; Snow and Parker 1998).Species and population genetic assessment requires a reliable source of biological material. Among different procedures to obtain DNA, non-invasive sampling seems to be very attractive, since it allows genetic analysis of several individuals without having to catch, handle or even observe them (H?ss et al. 1992; Taberlet and Bouvet 1992; Morin et al. 1993). The source of DNA can be hairs, feces, urine, shed feathers, snake skin, sloughed whale skin, eggshells and even skulls in owl pellets. However, this strategy usually Results in a low quantity and poor quality DNA and also does not provide individual identification, which limits its potential. In contrast, non-destructive sampling, that implies the use of tissues (blood, skin, scales, muscle biopsy) without critical damages to the animals, can exploit the full potential of DNA analyses including individual and sex determination, relatedness estimates, pedigree reconstruction, determination of the effective population size and the level of genetic polymorphism within and between populations (Taberlet et al. 1999).Liver and muscle tissue represent the most common used sources of fish DNA. However, non-destructively DNA isolation is desirable, especially when large populations or threatened species have to be analyzed. Although DNA can be successfully obtained from muscle (Hilsdorf et al. 1999) or blood samples of fish (Cummings and Thorgaard 1994; Estoup et al. 1996; Martinez et al. 1998) without the sacrifice of the animals, adult individuals of some species are often too small to be effectively sampled by muscle biopsy or drawing blood.The sampling strategy can be overcome by non-destructive procedures for DNA isolation from fish fins or scales. In the present paper, an improved DNA extraction method is described, using a lysis buffer containing a high urea concentration and further DNA purification with phenol-chloroform. The DNA-sampling method provides high-quality and high-quantity DNA useful as template in polymerase chain reaction (PCR) experiments and allows the maintenance of the individuals without disturbance in their health or behavior.