Oxidative metabolism in caste differentiation in honeybees: number and structure o...
| Grant number: | 07/04859-5 |
| Support type: | Scholarships in Brazil - Doctorate |
| Effective date (Start): | March 01, 2008 |
| Effective date (End): | May 31, 2011 |
| Field of knowledge: | Biological Sciences - Genetics |
| Principal Investigator: | Klaus Hartmann Hartfelder |
| Grantee: | Sergio Vicente de Azevedo |
| Home Institution: | Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil |
Abstract In the honey bee, Apis mellifera, the female castes, queen and worker, show differences in their anatomy, physiology and behaviors, which enhance efficiency in the reproductive tasks performed by the queen and maintenance of the beehive by the workers, respectively. The differentiation of the castes into a worker or queen phenotype depends on the diet offered to the female larvae during the growth period. This causes differences in the titers of the morphogenetic hormones juvenile hormone and ecdysteroids. While these hormones have important functions in the subsequent differentiation of organs and tissues, which eventually will culminate in the expression of different phenotypes, information about mechanisms able to integrate the signal provided by the diet with the endocrine system is still lacking. Recent studies in insects, including Apis mellifera, have pointed to the role of the insulin signaling pathway (IIS) as a possible cue integrating the nutritional stimulus with the developmental response in each caste. This is of interest because the insulin signaling module is highly conserved in metazoans, as it allows the organism to adapt to the prevailing nutritional conditions. This project aims at establishing the relationship between the components of the IIS pathway with the differentiation of the female honey bee castes, and to investigate the role of this pathway in the division of labor among adult workers. The transcriptional profiles of genes involved in the IIS pathway (InR1, InR2, ILP1 and ILP2) will be investigated by qRT-PCR, during the critical larval phases of caste development and in adult workers. Going beyond these analyses of transcriptional profiling, we will also use three functional approaches: first, the analysis of the activation pattern of insulin receptor by Western Blotting with specific antibodies to the phosphorylated form of these receptor tyrosin kinases; second, the silencing of the insulin receptor genes by dsRNA application; and third, a pharmacological inhibition of the phosphatidylinositol 3-kinase (PI3K), an essential IIS element, by Wortmaninn. The treated bees will be analyzed with respect to morphology, rates of insulin receptor (InR1 and InR2) and insulin-like peptide (ILP1 and ILP2) transcription, and their juvenile hormone titer will be determined by RIA. The relationship of the IIS pathway with division of labor among adult workers will be verified using single cohort colonies and analyzing by qRT-PCR the transcriptional profiles of IIS genes (InR1, InR2, ILP1 and ILP2) in workers performing different tasks. | |