RAPID ISOLATION OF DNA FOR GENETIC SCREENING OF CATFISHES BY POLYMERASE CHAIN-REACTION

We evaluated two methods, boiling and microwave irradiation, for the r apid isolation of DNA from barbel, adipose fin, and blood of channel c atfish Ictalurus punctatus. Compared with routine DNA isolation method s, these procedures were fast (microwaving, 2-4 min; boiling, 10-18 mi n), simple, and inexpensive (about US$0.10/fish). Samples of DNA isola ted from barbels of small (mean +/- SD, 2.9 +/- 1.0 g) and large (290 +/- 43 g) fish were of high purity (ratios of absorbances at 260 and 2 80 nm, A260/A280 = 1.72-1.90) and were between 0.29 and 0.67 mug/muL i n concentration. Samples of DNA isolated from barbel, adipose fin, and blood of small fish, by either method, were used successfully for ana lysis by polymerase chain reaction (PCR). Samples isolated by boiling of barbel and blood from large fish also proved useful for PCR analysi s. These DNA isolation procedures would be useful for rapid genetic sc reening of channel catfish. Removal of the barbel for tissue analysis would also enable direct marking of fish, and after analysis, individu als designated for further study could be identified.