Developmental Expression Profile Of Cockroach Vitellogenin Genes Vg 1 And 2

The fat body of female Periplaneta americana is the main site of vitellogenins (Vgs) synthesis. The Vgs are large molecules synthesized in the fat body and encoded by two different Vg genes (Vg1 and Vg2). The present study indicates that both Vg genes are represented in the genome by a single copy as revealed by Southern blot analysis.The Vg2 gene is predominantly expressed in the fat body cells and its expression preceded that of Vg1 gene. The expression profile and level of Vg genes are found to be synchronized and up-regulated by the hemolymph JH titer and suppressed by the ecdysteroid titer during vitellogenesis, as revealed by RT-PCR and real time PCR analysis.The differences in the expression levels of Vg genes, suggest the possible differences between the two genes in their responsiveness to the hemolymph JH titer and will pave the way toward further investigation on the JH responsive elements that regulate the expression of these two genes.