Systemic orchestration of cell size throughout the body: Influence of sex and rapamycin exposure inDrosophila melanogaster

Abstract

Along with differences in life histories, metazoans have evolved vast differences in cellularity, involving changes in the molecular pathways controlling the cell cycle. The extent to which the signalling network systemically determines cellular composition throughout the body and whether tissue cellularity is organized locally to match tissue-specific functions are unclear. We cultured genetic lines of Drosophila melanogaster on food with and without rapamycin to manipulate the activity of TOR/insulin pathways and evaluate cell-size changes in five types of adult cells: wing and leg epidermal cells, ommatidial cells, indirect flight muscle cells, and Malpighian tubule epithelial cells. Rapamycin blocks TOR multiprotein complex 1, reducing cell growth, but this effect has been studied in single cell types. As adults, rapamycin-treated flies had smaller bodies and consistently smaller cells in all tissues. Regardless, females eclosed with larger bodies and larger cells in all tissues than males. Thus, differences in TOR activity and sex were associated with the orchestration of cell size throughout the body, leading to differences in body size. We postulate that the activity of TOR/insulin pathways and their effects on cellularity should be considered when investigating the origin of ecological and evolutionary patterns in life histories.

Systemic orchestration of cell size throughout the body: influence of sex and rapamycin exposure in Drosophila melanogaster

“…The datasets, R code and materials supporting this article have been uploaded as part of the electronic supplementary material [76]. The early version of the manuscript was deposited at bioR X iv -the preprint server for Biology: https://doi.org/10.1101/ 2023.01.11.521715 [77].…”

Heat tolerance in Drosophila melanogaster is influenced by oxygen conditions and mutations in cell size control pathways

“…For example, at high temperatures, small-celled fish species were found to tolerate hypoxia better than large-celled species [27]. In other studies, small-celled forms of adult D. melanogaster were induced developmentally by larval feeding with rapamycin, a drug that downregulates the activity of the TOR kinase in TOR complex 1, reducing downstream signalling coming from this part of the TOR/insulin pathways [63,64]. The small-celled flies in these studies showed better flight performance under hypoxia than large-celled flies, and this effect was temperature-dependent [26], but they suffered increased mortality during early adulthood [63].…”