Rapid flow cytometry method for ploidy determination in salmonid eggs

Abstract. A rapid and simple method for ploidy determination by Row cytometry was developed for rainbow trout, Oncorhynchus mykiss Walbaum, and brown trout, Salmo trutta L., using commercially available reagents, and protocols previously implemented for plant tissues. The whole egg was directly chopped up in buffer, to release nuclei in an intact state. After filtration, the nuclei suspension was stained with a specific DNA fluorochrome and analysed by flow cytometry, using a compact, one-parameter cytometer. Within minutes, histograms of high quality were obtained, with a very good reproducibility, allowing unambiguous discrimination of diploids and triploids. Preliminary results indicate that the same methodology could be used for non-destructive analysis of young fish, using small samples of fin or muscle.