DNA-DAMAGE CAUSED BY COMMON CYTOLOGICAL FIXATIVES

Tissues from nine species of plants and fungi were treated separately with eight solutions, including seven cytological fixatives (3.7% form aldehyde at pH 3.0 and 7.0, FAA at pH 3.0 and 7.0, 1% glutaraldehyde a t pH 3.0 and 7,0, and Lavdowsky's fluid at pH 3.0) and one storage buf fer (SED = NaCl-EDTA-DMSO, pH 7.0). DNA from untreated tissue and SED- treated tissue was of high molecular weight (> 50 kb). DNA from glutar aldehyde-treated tissues averaged 20 kb in length, while DNA from all other treatments averaged less than 8 kb in length. Each DNA was subje cted to amplification using the polymerase chain reaction, followed by sequencing of 250 bp near the 3' end of the nuclear rRNA small subuni t gene. Glutaraldehyde treatments (at pH 3.0 and 7.0) produced damaged bases at rates of 0.0% to less than 0.1%. Treatments with Lavdowsky's fluid (containing mercuric chloride), FAA at pH 7.0, and SED produced rates of 0.0% to 3.6%. FAA at pH 3.0 produced rates of 7.6% to 15.6%. Nearly 100 attempts to amplify from specimens treated with 3.7% forma ldehyde (at pH 3.0 and 7.0) failed, indicating extreme damage to the D NA. (C) 1998 Elsevier Science B.V. All rights reserved.