W-enriched satellite sequence in the Indian meal moth, Plodia interpunctella (Lepidoptera, Pyralidae)

The W chromosome of most lepidopteran species represents the largest heterochromatin entity in the female genome. Although satellite DNA is a typical component of constitutive heterochromatin, there are only a few known satellite DNAs (satDNAs) located on the W chromosome in moths and butterflies. In this study, we isolated and characterized new satDNA (PiSAT1) from microdissected W chromosomes of the Indian meal moth, Plodia interpunctella. Even though the PiSAT1 is mainly localized near the female-specific segment of the W chromosome, short arrays of this satDNA also occur on autosomes and/or the Z chromosome. Probably due to the predominant location in the non-recombining part of the genome, PiSAT1 exhibits a relatively large nucleotide variability in its monomers. However, at least a part of all predicted functional motifs is located in conserved regions. Moreover, we detected polyadenylated transcripts of PiSAT1 in all developmental stages and in both sexes (female and male larvae, pupae and adults). Our results suggest a potential structural and functional role of PiSAT1 in the P. interpunctella genome, which is consistent with accumulating evidence for the important role of satDNAs in eukaryotic genomes.