A factorial design experiment as a pilot study for noninvasive genetic sampling

Noninvasive genetic sampling has increasingly been used in ecological and conservation studies during the last decade. A major part of the noninvasive genetic literature is dedicated to the search for optimal protocols, by comparing different methods of collection, preservation and extraction of DNA from noninvasive materials. However, the lack of quantitative comparisons among these studies and the possibility that different methods are optimal for different systems make it difficult to decide which protocol to use. Moreover, most studies that have compared different methods focused on a single factor – collection, preservation or extraction – while there could be interactions between these factors. We designed a factorial experiment, as a pilot study, aimed at exploring the effect of several collection, preservation and extraction methods, and the interactions between them, on the quality and amplification success of DNA obtained from Asiatic wild ass (Equus hemionus) faeces in Israel. The amplification success rates of one mitochondrial DNA and four microsatellite markers differed substantially as a function of collection, preservation and extraction methods and their interactions. The most efficient combination for our system integrated the use of swabs as a collection method with preservation at ?20 °C and with the Qiagen DNA Stool Kit with modifications as the DNA extraction method. The significant interaction found between the collection, preservation methods and the extraction methods reinforces the importance of conducting a factorial design experiment, rather than examining each factor separately, as a pilot study before initiating a full‐scale noninvasive research project.     

Effect of Temperature on Growth, Cell Size, and Free Amino Acid Pool of the Thermophilic Ciliate Cyclidium citriullus

SYNOPSIS. A clone of Cyclidium citrullus , adapted to growth at 18, 27, 37, 43, and 46 C had an optimum at 43 C, with 6.5 divisions/day. Transfer of cells previously grown at 43 or 46 C to 18 C resulted in death of most of the cells, transfer to 27 C increased the lag period, and transfer from 18 C to 37 or 46 C was followed faster division. All cells died at 48 C; some divided before death. At the temperatures employed maximum cell sizes (length and width) were achieved in the early log phase. At 43 C, however, the early log phase cells were smaller. Quantitative and qualitative differences in the free amino acids in the cells were found in ciliates grown at 18, 43, and 46 C; the highest amount/cell was found at 18 C, and the lowest at 43 C. High concentration of proline was noted only at 18 C.