Biology subjects

Gage, M. J.

Publications and source records attributed to Gage, M. J..

3 recordsLinked to original sources

bioRxiv2026

Transcriptomic profile of a rat jaw opener (anterior digastric) and a jaw closer (superficial masseter).

Mammalian skeletal muscle research predominantly focuses on locomotor muscles, and feeding related muscles remain less extensively characterized despite their role in mastication, mandibular stabilization, and swallowing. In this study, we investigated the transcriptomic specialization of three functionally and developmentally unique rat muscles: the anterior digastric (AD), a jaw opening muscle; the superficial masseter (SM), a jaw closing muscle; and the Sternohyoid (SH), a non-mandibular muscle involved in swallowing. Differential gene expression and weighted gene co-expression network analysis were used to characterize the transcription level features associated with their distinct roles. Our results indicated that all three muscles predominantly expressed fast-twitch contractile isoforms. However, the AD showed lower overall expression of several contractile gene families, including myosin heavy chain, myosin light chain, and tropomyosin isoforms, while exhibiting elevated expression of slow/oxidative myosin isoforms like Myh7 and Myh2. Network analysis revealed that modules correlated with AD are strongly enriched for fatty acid catabolism, mitochondrial energy production, and vascular/extracellular matrix remodeling. Additionally, AD and SM shared a distinct gene set compared to SH, highlighting their common developmental origin from the first branchial arch. Our findings show that the rat feeding related muscles possess unique transcriptomic profiles shaped by their contractile functions, developmental origins, and metabolic functions.

bioinformatics↗

bioRxiv2023

Socially plastic responses in females are robust to evolutionary manipulations of adult sex ratio and adult nutrition

BackgroundSocially plastic behaviours are widespread among animals and can have a significant impact on fitness. Here we investigated whether the socially plastic responses of female Drosophila melanogaster can evolve in predictable ways following long term manipulation of adult sex ratio and adult nutrient availability. Previous reports show that female D. melanogaster respond plastically to their immediate same-sex social environment by altering their fecundity, laying fewer eggs after they mate if previously exposed to other females, Fecundity is also highly sensitive to a females immediate nutritional status, being significantly reduced when dietary protein in particular is scarce. On this basis, we predicted that an evolutionary history of exposure to variation in adult sex ratio and adult nutritional environment would select strongly upon a females plastic fecundity responses. ResultsWe used females that had been drawn from replicated lines that had experienced an evolutionary history of male biased, female biased or equal adult sex ratios and either standard or low-quality adult nutrition. We tested the specific predictions that a history of elevated competition among females (in female-biased regimes) would select for increasingly sensitive plastic fecundity responses to the presence of conspecifics, and that these would be magnified under poor nutritional resource regimes. In contrast to the expectations, we found that the plastic responses in females were strikingly robust to perturbations of both sexual competition and nutrient availability and did not differ significantly across any of the evolutionary regimes. The lack of response is not explained by an insufficient strength of selection. For example, among females held in isolation prior to mating, we did observe significant evolutionary responses in virgin egg according to nutritional regime and in virgin egg retention to sex ratio regime. ConclusionThe lack of variation in the existence and magnitude of predicted plasticity is consistent with the idea that the costs of maintaining fecundity plasticity in females are low, benefits high, and that plasticity itself can be hard wired.

evolutionary biology↗

bioRxiv2022

Frequency-dependent viscosity of salmon ovarian fluid has biophysical implications for sperm-egg interactions

Gamete-level sexual selection of externally fertilising species is usually achieved by modifying sperm behaviour with mechanisms thought to alter the chemical environment in which gametes perform. In fish this can be accomplished through the ovarian fluid, a substance released with the eggs at spawning. While its biochemical effects in relation to sperm energetics have been investigated, the influence of the physical environment in which sperm compete remains poorly explored. Our objective was therefore to gain insights on the physical structure of this fluid and potential impacts on reproduction. Using soft-matter physics approaches of steady-state and oscillatory viscosity measurements, we subjected salmon ovarian fluids to variable shear stresses and frequencies resembling those exerted by sperm swimming through the fluid near eggs. We show that this fluid, which in its relaxed state is a gel-like substance, displays a non-Newtonian viscoelastic and shear-thinning profile, where the viscosity decreases with increasing shear rates. We concurrently find that this fluid obeys the Cox-Merz rule below 7.6 Hz and infringes it above, thus indicating a shear-thickening phase where viscosity increases provided it is probed gently enough. This suggests the presence of a unique frequency-dependant structural network with relevant implications on sperm energetics and fertilisation dynamics.

evolutionary biology↗