Simple DNA repeats and sex chromosome differentiation in Asellus aquaticus (Crustacea, Isopoda)

Abstract

The crustacean isopod species Asellus aquaticus does not usually have recognizable sex chromosomes. We previously identified a Y chromosome marked by two heterochromatic bands in some males of a population from the Sarno river near Naples. In this work we used oligonucleotide probes to test the presence and possible sex-specific distribution of five simple repeat motifs in the genome of male and female individuals from the Sarno population. The five oligonucleotide probes were hybridized to enzyme-restricted genomic DNAs and the chromosome location of two probes was tested using fluorescence in situ hybridization. Our results show that only the (TCC) repetitive simple sequence has a sex-specific hybridization pattern and presents a significant accumulation on the Y chromosome in the region included between the two heterochromatic areas. Moreover the GGAAT sequence is not present in the genome of A. aquaticus in any detectable quantity.

The status of supergenes in the 21st century: recombination suppression in Batesian mimicry and sex chromosomes and other complex adaptations

“…The same is true in insects; for instance, the XY systems in Diptera are nonhomologous (Toups and Hahn 2010;Pease and Hahn 2012;Vicoso and Bachtrog 2015). Other animal taxa have female heterogamety, with ZW systems, as in birds (Zhou et al 2014), Lepidopteran insects (Suetsugu et al 2013) and Crustacea (Juchault and Rigaud 1995;Volpi et al 1995), and these too often evolved independently, although changes from XY to ZW are also known (Ogata et al 2008), and systems with males ZZ and females with a single Z have been detected in Dipteran flies, which mostly have XY systems (Vicoso and Bachtrog 2015). In all these taxa, at least some species' sex chromosomes have physically large nonrecombining regions that have characteristics differing from most of the rest of the genomes.…”

“…) and Crustacea (Juchault and Rigaud ; Volpi et al. ), and these too often evolved independently, although changes from XY to ZW are also known (Ogata et al. ), and systems with males ZZ and females with a single Z have been detected in Dipteran flies, which mostly have XY systems (Vicoso and Bachtrog ).…”