Caveolin-3 regulates slow oxidative myofiberformation in female mice

Objectives:Caveolin-3(Cav-3)plays a pivotal role in maintaining skeletal muscle mass and function.Mutations ordeletions of Cav-3 can result in the development of variousforms of myopathy,which affect the integrity and repaircapacity of musclefiber membranes.However,the potentialeffect of Cav-3 on myofiber type composition remainsunclear.Methods:To investigate the effect of Cav-3 on musclestrength and running capacity,we examined the grip forcetest and the low/high-speed running test.Oxidative andglycolytic myofiber-related genes,proteins,and skeletalmusclefiber composition were measured to determine therole of the Cav-3 in oxidative myofiber formation.Results:We report the impact of Cav-3 on enhancing muscleendurance performance in female mice,and the discovery ofa new physiological function to increase the proportion ofslow-twitch oxidative musclefiber by analyzing thegastrocnemius and soleus.Skeletal muscle-specific ablationof Cav-3 in female mice increased oxidative myofiber-relatedgene expression and type I oxidative myofiber composition,with resultant improvements in endurance performance.Inmale mice,the absence of Cav-3 in skeletal muscle reduced inthe expression of glycolyticfiber-related genes and proteins.Conclusions:This study identified Cav-3 as a regulatorof slow-twitch oxidative musclefiber formation acting onfemale mice,which may provide a potential target forimproving muscle oxidative function.

What does it mean to be a macronutritional generalist? A five-year case study in wild rhesus macaques(Macaca mulatta)

DEAR EDITOR,Dietary generalism is widely associated with ecological flexibility,but the mechanisms of this relationship remain poorly understood.A recently developed body of theory on the relationship between generalism/specialism at the levels of foods selected vs.nutrients ingested,termed multi-level dietary niche theory,offers a powerful opportunity to deepen our understanding of the dietary generalist-specialist spectrum and its ecological significance.

Seasonal diet and microbiome shifts in wild rhesus macaques are better correlated at the level of nutrient components than food items

Food supply is one of the major drivers of animal behavior,and the gut microbiome is an important mediator be-tween food supply and its effects on physiology.However,predicting the outcome of diet change on microbiome and consequences for the animal has proven extremely challenging.We propose this reflects processes occurring at different scales.Inadequate accounting for the multi-level complexity of nutrition(nutrients,foods,diets)obscures the diet influence on microbiome and subsequently animal.Here,we present a detailed year-round,multi-level analysis of diet and microbiome changes in a wild population of a temperate primate,the rhesus macaque(Macaca mulatta).Total daily food and nutrient intake of 6 male and 6 female macaques was monitored in each of the 4 sea-sons(total 120 days observations).For each individual,we found significant variation in the microbiome between all 4 seasons.This response was more strongly correlated with changes in macronutrient intake than with food items and much of the response could be explained at the level of 6 ecological guilds—sets of taxa sharing similar responses to nutrient intake.We conclude that study of diet,microbiome,and animal performance in ecology will more effectively identify patterns if diet is recorded at the level of nutrient intake.Although microbiome response to diet does show variation in species-level taxa in response to food items,there is greater commonality in response at the level of guilds.A goal for microbiome researchers should be to identify genes encoding microbial attributes that can define such guilds.