Nucleic acids content or integrity in biological samples constitute an important limiting factor for DNA typing technology. In the present work, several procedures are tested for the extraction and purification of DNA from different biological sources at different stages of preservation. The methodology we describe al lows PCR‑based DNA typing from an assorted range of biological specimens: blood, tissues, buccal cells and follicle hairs. We also have analysed the impact of the preservation method, ethanol or formalin fixation, on DNA integrity from collected archival materials and hence the suitability for genetic surveys.
The particular example we show refers to sex identification in different mammals by using selective amplification of the ZFX/ZFY loci and subsequent RFLPs analysis. However, this technique sometimes presents problems for sex diagnosis in ruminant species. To improve the accuracy of this sex identification method, we have implemented the technique with an appropiate control in the RFLPs analysis that ensures a correct sex assignation: the pUC18 plasmid.