Physical mapping of rDNA and satDNA in A and B chromosomes of the grasshopper Eyprepocnemis plorans from a Greek population

Abstract

Adult males and females of the grasshopper Eyprepocnemis plorans from a Greek population were analysed by C-banding, silver impregnation and double FISH for two DNA probes, i.e. ribosomal DNA (rDNA) and a 180- bp tandem repeat DNA (satDNA). This population shows characteristics of rDNA location in A chromosomes that are intermediate between those previously reported for eastern (Caucasus) and western (Spain and Morocco) populations. The four rDNA clusters revealed by FISH in chromosomes X, 9, 10 and 11 in Greek specimens imply two more than the two observed in chromosomes 9 and 11 in the Caucasus, but less than the 12 observed in all chromosomes in Morocco. Remarkably, the X chromosome bears one of the new rDNA locations in Greece with respect to the Caucasus, but it appears to be inactive, in contrast to X chromosomes in western populations, which are usually active. B chromosomes were very frequent in the Greek population, and three variants differing in size were observed, all of these being largely composed of rDNA, with the exception of a small pericentromeric satDNA cluster. The high B frequency suggests that B chromosomes in this population might behave parasitically, in resemblance to Bs in western populations.