The western honey bee, Apis mellifera, has become a model organism for studies of social structure and behavior in insects. The genome of A. mellifera is well-described and allows us to investigate specific genes that may be important in modulating social behavior, especially those involved with nutrition. In A. mellifera, nutrition is important in mediating task allocation within a colony, with genes displaying differential expression between the two worker tasks, nurses and foragers. In this thesis, I first aimed to identify a nutritionally-linked candidate gene that influences social structure. First, a comparative transcriptome was completed by comparing transcripts of nurse and forager brains. We identified 89 differentially expressed genes between the brains of A. mellifera nurses and foragers and categorized those with known functions into: immune response, binding, regulatory, enzyme activity, metabolism, transport, cellular component, and localization. Of these genes, we identified major royal jelly protein 1 (mrjp1) as a candidate gene of interest due to its involvement in nurse behavior and nutrition. mrjp1 was found to be upregulated 5.0-fold higher in nurses than in foragers, and is part of a larger family of major royal jelly proteins (mrjps) that range in function from nutrition, immune function, and nitrogen storage. To further assess the relationship of the mrjp among Hymenoptera, a phylogenetic analysis of mrjp lineages was conducted to study the evolutionary context of the gene in relation to other Hymenopteran species. By utilizing domains of mrjp homologs, we confirmed that mrjps of Apis evolved independently from those of other Hymneopteran species and diversified into nine copies and one pseudogene. The mrjp family has subfunctionalized into different roles across Hymenoptera, and some mrjps have been shown to possess unique nutritive functions within Apis. In A. mellifera, the function of mrjp1 is generally understood to be involved in the synthesis of royal jelly. However, little is known about the hormonal regulation of this gene. To test the effect of juvenile hormone, a hormone involved in task allocation, a JH analog bioassay was conducted through topical application of methoprene on the abdomens of nurse bees to measure the expression of mrjp1. No statistical evidence was found to elucidate the nature of the relationship between mrjp1 and JH.
Jumana Hayat (Thu,) studied this question.