Dr. Walker's group has developed an excellent
preservative solution for field samples. It contains 80%
ethanol, 20% glycerol and 0.25% mercapto-ethanol
(prepared by mixing 80 ml absolute ethanol, 20 ml pure
glycerol and 0.25 ml of mercapto-ethanol). Samples are
crushed or homogenized in this at 1 part sample to 10
parts preservative and survive storage for a reasonable
length of time at room temperature. At the laboratory,
supernatant preservative is removed before nucleic acid
extraction (RNA or DNA) from tissues in the usual
manner for use as a PCR template.