Extraction of dna from sheep white blood cells

Common methods for the extraction of DNA from whole blood involve several phenol extraction steps. Phenol is corrosive and toxic, and the extraction steps are time-consuming, limiting the number of samples that can be processed. Two other methods using high salt or guanidine hydrochloride were tested for extraction of DNA from sheep blood. Extraction using the guanidine hydrochloride method resulted in a gelatinous material that failed to resuspend in TE buffer. The high salt method produced a good yield of high molecular weight DNA as determined by agarose gel electrophoresis. The mean yields of DNA from 100 samples of 20 ml of whole blood extracted by either the phenol or the high salt methods were 0.50 mg (SD=0.19) and 0.64 mg (SD=0.26) respectively. The quality of the DNA extracted by the high salt method was equivalent to that extracted by the phenol method and the DNA from both methods was digested to completion with a range of restriction enzymes and was suitable for analysis by Southern blotting. The high salt method can be used routinely for the extraction of DNA from sheep samples, increasing the number of samples processed and facilitating DNA extraction for genetic linkage analysis and diagnostic tests