Variation in the Maximum Number of Nucleoli in Diploid and Triploid Common Carp

Abstract

The variation in the maximum number of nucleoli per cell in diploid and triploid common carp Cyprinus carpio related to their age was found in attempts to verify the validity of nucleoli counting as an indirect method for polyploidy identification in fish. Although in most cases diploid com-mon carp have a maximum of two nucleoli per cell, some individuals with a maximum of either one, three, and four nucleoli per cell were observed. Anomaly in the silver-stained appearance and the maximum number and distribution of nucleoli were also found in the liver cells, but no clear dif-ference in the maximum number or distribution was found in other somatic tissues (gill, intestine, kidney, spleen, or caudal fin) in either male or female. Most triploids, calibrated by chromosome counts, derived from breeders with a maximum of two nucleoli per cell, had a maximum of three nucleoli per cell. But the distribution of nucleoli in diploid and triploid individuals showed considerable variation, and the maximum number of nucleoli per cell of some triploids changed from two at 1 year to three at 3 years after hatching.