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Abstract
Stem cells are precursor cells for all the specialized cells in our body. The stem cell niche or microenvironment plays an important role in maintaining and regulating stem cell activities. A variety of physiological and environmental factors have also been known to affect stem cell activity.However, little is known about how they regulate their mitotic activity. Drosophila gonads are an excellent model to study stem cell activity in response to physiological and environmental cues.
Our lab discovered that germline stem cell division frequency increases on mating in Drosophila melanogaster males. Germ line stem cells divide faster in males heavily mated with virgin females as compared to non-mated males. The aim of this project was to investigate the mechanism causing this upregulation. In chapter 2, we report that the entire mating behavior is required to cause this upregulation suggesting that the signal maybe be a hormone or a neurotransmitter.
We generated a list of receptors expressed on testis tip using RNA sequencing. This sequencing data also revealed a number of G-protein coupled receptors. In chapter 3, we have obtained data which suggests that two different G-proteins, G-αi and G-γ1, are involved in this process. We also report the results of our screening using RNA-interference technique, to identify the receptors involved in this pathway. Our data implicated seven GPCRs in this pathway. These were the serotonin receptors 5-HT1A, 5-HT1B,5-HT7, the methuselah receptors Mth and Mthl-5, the octopamine receptor Octβ2R and a putative receptor encoded by the gene CG12290. Chapter 4 details the results of our efforts to identify the signaling molecule upstream of these receptors. We discovered that when males were fed with a certain concentration of serotonin with their food, their germline stem cells divide more frequently. This was similar to an increase in germline stem cell divisions on mating suggesting that serotonin may be upstream of this pathway. This project has enabled us to better understand how germline stem cells regulate their mitotic activity.
Our lab discovered that germline stem cell division frequency increases on mating in Drosophila melanogaster males. Germ line stem cells divide faster in males heavily mated with virgin females as compared to non-mated males. The aim of this project was to investigate the mechanism causing this upregulation. In chapter 2, we report that the entire mating behavior is required to cause this upregulation suggesting that the signal maybe be a hormone or a neurotransmitter.
We generated a list of receptors expressed on testis tip using RNA sequencing. This sequencing data also revealed a number of G-protein coupled receptors. In chapter 3, we have obtained data which suggests that two different G-proteins, G-αi and G-γ1, are involved in this process. We also report the results of our screening using RNA-interference technique, to identify the receptors involved in this pathway. Our data implicated seven GPCRs in this pathway. These were the serotonin receptors 5-HT1A, 5-HT1B,5-HT7, the methuselah receptors Mth and Mthl-5, the octopamine receptor Octβ2R and a putative receptor encoded by the gene CG12290. Chapter 4 details the results of our efforts to identify the signaling molecule upstream of these receptors. We discovered that when males were fed with a certain concentration of serotonin with their food, their germline stem cells divide more frequently. This was similar to an increase in germline stem cell divisions on mating suggesting that serotonin may be upstream of this pathway. This project has enabled us to better understand how germline stem cells regulate their mitotic activity.