MEASUREMENT BY FLOW-CYTOMETRY OF GENOMIC AT GC RATIO AND GENOME SIZE/

Flow cytometry with the AT-specific fluorochrome Hoechst 33258 (HO) an d the GC-specific fluorochrome olivomycin (OM) was used for measuremen t of base pair specific DNA content in 20 species of vertebrates. The results were found to be in good correlation with the biochemical lite rature on base pair frequencies (r = 0.972, P < 1 x 10(-8)). This corr elation allows one to determine the percent of GC/AT-pairs and genome size from flow cytometric data. The genome sizes obtained were compare d with the literature data on flow cytometric genome size values deter mined with the use of propidium iodide (PI) that is usually believed t o be non-base pair specific. The results were found to be in general a greement; however, the previously reported slight GC-preference of PI is confirmed. The optimal conditions for flow cytometry of AT/GC ratio and genome size with the use of OM and HO are discussed. The approach can be useful for research in ecology, fisheries science, species con servation, and other environmental studies as a tool for rapid survey of a vast array of specimens. (C) 1994 Wiley-Liss, Inc.