Circadian rhythm dependent regulation of myeloid cell development and function in drosophila melanogaster

Abstract

Circadian rhythms are the ubiquitously present regulators of periodic behavior in all organisms. These intrinsic rhythms, entrained by the seasonal availability and daily period of light in the organism‘s surroundings, play a crucial role in organizing the body‘s immensely varied processes at precise points of time during a 24 hour period. They control processes from the likes of the sleep-wake cycle, immunological responses, release of hormones, metabolism, to many physical, mental, and behavioral changes within the body. Dysregulation in circadian rhythms has been linked to various health conditions such as sleep disorders such as insomnia, eating disorders, mental disorders such as bipolarity, obesity, diabetes, and also to seasonal alterations in mental disposition, such as the winter blues. Needless to say from here, understanding of these rhythms is indispensable if we have to look beyond the surface when it comes to several chronic and debilitating health issues. This particular study focuses on one such aspect, the regulation of blood cell development by circadian rhythms. The model system opted for is Drosophila melanogaster and the organ of interest is the hematopoietic organ lymph gland, present in the fruit fly during the larval stages. Upon disruption of circadian rhythms, there is marked increase in the level of differentiation and a concurrent decline in the level of progenitor maintenance in the lymph gland. The unchanging number of hematopoietic niche cells under circadian disruption indicates that the increased differentiation might not be due to a non-functional niche. Furthermore, macrophages in circadian disrupted conditions exhibit substantially increased phagocytic activity. This is especially relevant in the light of bacterial infection in which case the macrophages show a sharp rise in their phagocytic activity. In essence, the current study uncovers the role of circadian rhythms in the development as well as functioning of the myeloid cells found in Drosophila melanogaster.