Identifying Novel Pair-Rule Genes in Oncopeltus fasciatus

Abstract

Pair-rule genes encode transcription factors that play a significant role in the development of segments during the embryogenesis of insects. In Drosophila melanogaster, nine pair-rule genes have been identified. Although many developmental studies have focused on Drosophila, the establishment of segments that form sequentially after gastrulation in Oncopeltus fasciatus, milkweed bug, make it an important representative model to study. Earlier studies demonstrated that orthologs of the nine Drosophila pair-rule genes had no pair-rule like expression in Oncopeltus. The discovery of a pair-rule gene, Ofas-E75A, in Oncopeltus paved the way to looking for more pair-rule genes in this organism. We investigated whether a set of candidate genes exhibit pair-rule like expression, similar to Ofas-E75A, in Oncopeltus. These genes were selected based on their coexpression with Ofas-E75A. The expression patterns of these genes were assessed by synthesizing an antisense RNA probe, labeled with digoxigenin, targeting the gene of interest, then performing an in-situ hybridization using the RNA probe. Thus far, the expression patterns of two of the ten candidate genes have been examined. Ofas-000545 displayed staining in the thoracic segments and Ofas-000627 displayed expression along the midline in Oncopeltus. Neither displayed pair rule-like expression patterns. Identification of the expression patterns of the remaining eight genes is in progress. Whether they display pair-rule like expression patterns remains to be determined. If a gene is found to have a pair-rule like expression pattern, parental RNAi can be used to determine the function of the gene.