Apis mellifera is an attractive model for studying polymorphic systems because of its complex social organization, economic and ecological importance. Understanding the mechanisms involved in caste development in these bees is important to clarify questions about the evolution and maintenance of a social lifstyle in insects. Queens are responsible for colony reproduction and the workers for all other tasks in colony maintenance. The development of these female castes is based on a single genotype, that can alternatively give rise to a queen or worker phenotype depending on the diet received during the larval stages. Such differential feeding triggers endogenous responses in signaling pathways and the endocrine system that eventually result in differential gene expression related to the development of the two phenotypes. One of the main targets of these signaling processes is the reproductive system, which exhibits major differences between adult queens and workers, for instance the number of ovarioles. In workers, this number is drastically reduced as a result of extensive programmed cell death during the larval stage. This current project aims to analyze patterns of gene expression in the ovaries of honey bees in the critical larval stages of caste differentiation. From a series of previously performed microarray assays we compiled a set of 20 genes for validation and further in-depth analysis. For these we will design primers and analyze their expression by quantitative RT-PCR in samples from ovaries of both castes during the larval stages L4 and L5, which are critical for the development of the ovary phenotypes. The genes showing a clear pattern of differential expression, will be then analyzed in other organs presenting caste-specific variation and, in functional assays, we will evaluate the expression of these genes in response to juvenile hormone, which is a major endocrine factors regulating the development of queens and workers.
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