Extraction of high-quality host DNA from feces and regurgitated seeds: a useful tool for vertebrate ecological studies

DNA extraction methods for genotyping non-invasive samples have led to great advances in molecular research for ecological studies, and have been particularly useful for analyzing threatened species. However, scarce amounts of fragmented DNA and the presence of Taq polymerase inhibitors in non-invasive samples are potential problems for subsequent PCR amplifications. In this study we describe a novel technique for extracting DNA from alimentary tract cells found on external surfaces of feces and regurgitated seeds. The presence of contaminants and inhibitors is minimized and samples are preserved intact for use in other ecological research (e.g. trophic studies). The amplification efficiency and purity of the extracted DNA from feces were significantly higher than in commonly used extraction procedures. Moreover, DNA of two bird species was identified from seeds expelled by regurgitation. Therefore, this method may be suitable for future ecological studies of birds, and other vertebrate groups.

Comparación de métodos de extracción de ADN de sangre para detectar ADN fúngico por PCR / Comparison of different methods of DNA extraction from blood to detect fungal DNA by PCR

La infección fúngica invasora (IFI) está asociada a un alto índice de mortalidad, que alcanza el 50% debido a la frecuente falla en el tratamiento antifúngico. Existen dificultades para realizar un diagnóstico micológico rápido y certero dada la baja sensibilidad de los métodos convencionales, especialmente en pacientes neutropénicos y con SIDA. Numerosos métodos para diagnosticar infecciones micóticas basados en el estudio del ADN fúngico están actualmente en desarrollo. Nosotros evaluamos la utilidad de dos procedimientos de extracción y purificación del ADN fúngico presente en sangre para su posterior detección por PCR. Ambos métodos resultaron igualmente eficientes para obtener ADNs de óptima calidad y para realizar la técnica de PCR con los iniciadores universales para hongos ITS 1 e ITS 4.

Invasive fungal infections (IFI) are associated with high mortality by reaching levels of 50%, and also with a significant failure in antifungical treatments. This fact mostly obeys to difficulties in obtaining a fast and accurate mycologic diagnosis due to the low sensitivity of conventional methods, mainly in neutropenic and AIDS patients. Various methods based on fungal DNA study are currently being used for the diagnosis of mycotic infections. We herein evaluated two procedures of extraction and purification of fungal DNA in blood for their use in PCR detection. Both of them showed equal efficiency in obtaining high performance DNA with universal primers ITS 1and ITS 4 as target.