Chromosomal localization and partial sequencing of the 18S and 28S ribosomal genes from Bradysia hygida (Diptera: Sciaridae).

In insects, ribosomal genes are usually detected in sex chromosomes, but have also or only been detected in autosomal chromosomes in some cases. Previous results from our research group indicated that in Bradysia hygida, nucleolus organizer regions were associated with heterochromatic regions of the autosomal C chromosome, using the silver impregnation technique. The present study confirmed this location of the ribosomal genes using fluorescence in situ hybridization analysis. This analysis also revealed the partial sequences of the 18S and 28S genes for this sciarid. The sequence alignment showed that the 18S gene has 98% identity to Corydalus armatus and 91% identity to Drosophila persimilis and Drosophila melanogaster. The partial sequence analysis of the 28S gene showed 95% identity with Bradysia amoena and 93% identity with Schwenckfeldina sp. These results confirmed the location of ribosomal genes of B. hygida in an autosomal chromosome, and the partial sequence analysis of the 18S and 28S genes demonstrated a high percentage of identity among several insect ribosomal genes.