Master of Science
Honey bee workers deactivate their ovaries and are functionally sterile when a queen is present in the colony. I adopt a bioinformatics approach to up-date a model transcriptional regulatory network (TRN) to study gene-regulatory processes that regulate fecundity in workers. On splitting the network, I obtained nine clusters and each cluster conformed to properties associated with real-world networks. Two of the nine clusters are enriched for 'sterility genes' and contained single well-connected hub genes (GB44769, ftz-f1). The genes in the two clusters were functionally enriched for nucleic acid binding (GO:0003676) and nucleotide binding (GO:0000166). I identified homologous genes for my two clusters of interest and constructed corresponding gene regulatory networks for D. melanogaster. In these clusters, I found genes enriched for properties like embryo development in D. melanogaster such as arm, kay and r-l whose homologues in A. mellifera could be tested for their role in honey bee reproduction.
Summary for Lay Audience
Honey bees have an estimated total contribution of $2.57 billion in direct additional harvest value to the Canadian economy according to Agriculture and Agri-food Canada. Moreover, bees play a vital role in pollinating various plants that serve as a source of food to many species both large and small. Hence, the importance of bees cannot be disputed and is the subject of multiple research projects each year. An area of interest is the differences in behaviour displayed by the caste members of a bee colony. The queen is the most reproductive member of the colony influencing the behaviour of both the workers and drones. One behaviour change that has been noticed is the deactivation of worker ovaries in the presence of queen pheromones. These workers forgo their egg laying capabilities and take care of other duties around the hive like caring for the young, foraging and guarding the hive, etc. Social insect researchers have identified the suite of genes that may play a role in worker ovary de-activation in response to pheromone. However, a full understanding of how these genes interact to regulate the reproductive division of labor in colonies could be clarified. Over the last couple of decades, researchers have begun to realise that visualizing and studying a collection of genes in the form of a network – that is, a graph showing how individual genes interact with each other – makes it easier to identify key genes and their functionality, which is in part dependant on their position in the network. The Thompson lab has previously utilized network analysis to identify key genes involved in the pathway that regulates honey bee worker sterility. My thesis study attempts to advance this work by taking advantage of new information to up-date and re-analyze earlier work. Through this project, I aim to solidify our knowledge of the genes involved in the reproductive pathway of honey bees and provide an avenue for future research.
Choorakkat Unnikrishnan, Rahul, "Gene Regulatory Context of Honey Bee Worker Sterility" (2022). Electronic Thesis and Dissertation Repository. 9257.