Figure 4. Characterization of Bt-tra2, a putative sex determination gene in B. tabaci.

(A). The schematic drawing shows structural features of the two predicted Bt-tra2 isoforms (RS, arginine/serine rich domain; RRM, RNA binding domain). (B). Semi-quantitative transcriptional profile of Bt-tra2 transcripts throughout different developmental stages, including L1–L2 (1-2^rd instar larvae), L3 (3^rd instar larvae), L4 (4^rd instar larvae), female and male adults. The actin was used as a loading control. (C). The phylogenetic relationship of Tra2 RRM domains among different insect orders, including Hemiptera (B. tabaci and Acyrthosiphon pisum),Hymenoptera (Apis mellifera, Nasonia vitripennis, and Acromyrmex echinatior), Lepidoptera (Bombyx mori), Coleoptera (Tribolium castaneum), and Diptera (Drosophila melanogaster, Lucilia cuprina, and Musca domestica). Dots indicate amino acids identical to the predicted Bt-Tra2 RRM of the whitefly. RNP sequence elements (RNP1 and RNP2) are highlighted in boxes.