PHYSIOLOGY OF INSECTS

Author: CRUZ RODRÍGUEZ JOSEFA.
Year: 2005.
University: BARCELONA [www.ub.es].
Place of defense: UNIVERSIDAD DE BARCELONA.
Place of preparation: UNIVERSIDAD DE BARCELONA.

Summary: SUMMARY: In insects, the various transitions that occur over development, both embryonic as post-embrionario are regulated by pulses ecdisteroides, particularly by the 20-hidroxiecdisona (20E). This signal is transduce through transcription factors of the family of nuclear receptors, in particular the 20E joins heterodimero formed by the ecdisona receptor (EcR) and the product of the gene or / traespiracu / or (USP), and once united, activates a small number of early genes, which in turn amplify this signal by inducing so-called tardíos genes that control the biological response to the hormone. Within this gene cascade noteworthy functional axis formed by nuclear receptors EcR-HR3-FTZ-F1 which is involved in coordinating the larval dummy, as well as the onset of metamorphosis in Drosophi / for me / anogaster. It is important to stress that it is not known if the hierarchy of nuclear factors induced by 20E also exists and operates in more primitive insects with a development hemimetábolo as is our insect model B / attella germanica. So, we have conducted the cloñaje of ortólogos of nuclear receptors HR3 and FTZ-F1 in B. Germanica getting three isoforms of HR3 (BgHR3-A, BgHR3-B1YBgHR3-B2) And two of FTZ-F1 (BgFTZ-F1A and BgFTZ-F1B). We characterized the expression patterns of these transcribed and recipient of the ecdisona (BgEcR-A), which had previously cloned in our laboratory, in the last two phases ninfales well as during embryogenesis of B. Germanica. In addition, we analyzed the regulatory role that these nuclear receptors play during the nymphal development of B. Germanica, and especially in the process of moving. To that end, we used the technique of RNA interference (RNAi) mediated in vivo injection of intraabdominal double chain RNAs (dsRNA) from each of the genes to study. When these dsRNAs were injected into newly emerged females to sixth nymphal stage, most of the nymphs blocked were unable to complete the écdisis and died after 24-48 h. The phenotypic analysis showed that these individuals had duplication of the structures of origin ectodérmico and presenting changes in the levels of ecdisteroides hemolinfáticos. However, a certain percentage of the nymphs treated dsBgEcR-Ay dsBgFTZ-F1 were able to complete the move imaginal, this allowed us to study processes that are affected by these two transcription factors during adulthood. Individuals interfered with dsBgEcR-A who moved to adult showed clear flaws in the extension of the two pairs of wings, for its part, the nymphs treated dsBgFTZ-F1 also had wings incorrectly positioned, although properly extended. The second phenotype observed in all patients treated with dsBgEcR-Ay dsBgFTZ-F1 who moved to adult is that the gland protorácica not turned. We extend the functional analysis of each of the nuclear receptors that we are examining, BgEcR-A, BgHR3 and BgFTZ-F1 the embryonic period of B. Germanica. The analysis of the embryos interfered to BgEcR-Ay BgFTZ-F1 showed that these individuals progressed until 48 h of embryonic development, introducing, however, significant defects that prevented further development. While those who were silenced for BgHR3, who were able to advance to the 8 s 96 hd 29c and development, presented defects in the development of the cephalic region from a severe level shortly, in which only appreciated some reduction or loss the lobes cefálicos until embryos that had lost all segments cefálicos.