Caracterização genética da região controladora do mtDNA e de loci de microssatélites das subpopulações de tursiops truncatus(cetacea, delphinidae) do complexo lagunar de Santo Antônio dos Anjos, Santa Catarina, e litoral norte do Rio Grande do Sul

Abstract

Museum specimens are an important source of DNA for taxonomic identifications and population genetics studies. This is especially true for rare species, which has great scientific value due to its small sample size in museums. Moreover, often, access to collections for performing molecular studies on these taxa is only possible through the use of nondestructive DNA extraction techniques. An alternative method, which avoids the destruction of museum samples and with an efficient DNA extraction is presented here for four bottlenose dolphins (Tursiops truncatus) specimens collected along the coast of Santa Catarina, Brazil, from 1985 to 2007. This is the first study in Brazil to amplify teeth DNA of T. truncatus for the mtDNA control region. Using a drill (Bosch GSR 14.4-2 model) with drill bits of about 2 mm, small holes were made in teeth of specimens of Tursiops truncatus physically adults deposited in the collection of the Laboratório de Mamíferos Aquáticos, Universidade Federal de Santa Catarina (LAMAQ/UFSC). Between 100-150 mg of powdered dentin/cementum were removed and demineralized for 7 days at 55° C with 950 µl of EDTA (0.5 M, pH 8). This material was incubated at 55° C overnight to the cells suffer digestion of proteins and RNA by the action of 300 µl of Buffer ATL, 20 µl Proteinase K and 1 µl of RNAse. The final step was completed by the extraction kit Qiagen DNA Investigator (QIAGEN®). The efficiency of the extracted DNA was tested by amplification of a fragment of at least 362 base pairs (bp) of the mitochondrial DNA control region in four specimens of T. truncatus. A total of two haplotypes were defined from 11 polymorphic sites. The high polymorphism detected is a possible consequence of the great genetic variability of the genus Tursiops. In cases where there is the subspecies hypothesis based on morphological data, molecular identification can help to assign these museum specimens to each ecotypes, being extremely important the use of efficient and nondestructive extraction methods, as showed here, to obtain satisfactory results and to conserve the specimens.