Biology subjects

Riddle, N. C.

Publications and source records attributed to Riddle, N. C..

5 recordsLinked to original sources

bioRxiv2025

Sex differences in DNA methylation in bats

Sex-biased longevity is observed across a wide range of animal taxa, including bats, for reasons not well understood. Patterns of cytosine methylation vary predictably with age in many organisms, offering a valuable means to investigate differences in patterns of aging at the molecular level. We tested sex differences in cytosine methylation across 14 bat species and compared patterns of age-associated variation. Sex differences were overrepresented on the X chromosome, showing a strong pattern of female hypermethylation within promoter regions. Sex and age-associated differences in methylation were non-randomly distributed with respect to proximity to putative sex hormone receptor binding sites, with sites hypermethylated in males and females tending to be underrepresented near androgen and estrogen receptor binding sites, respectively. Across species, we observed the relative steepness of male versus female slopes of age-associated variation was associated with the strength of precopulatory sexual selection, with especially strong trends towards male-biased age-associated slopes in two harem-polygynous species that exhibit female-biased longevity. Our results offer insights into how patterns of methylation differ across sexes and ages, and raise intriguing questions for future research, such as whether sex differences in molecular aging reflect sex-biased longevity, for which records in bats are sparse.

evolutionary biology↗

bioRxiv2021

Exercise-induced changes in climbing performance

Exercise is recommended to promote health and prevent a range of diseases. However, how exercise precipitates these benefits is unclear, nor do we understand why exercise responses differ so widely between individuals. We investigate how climbing ability in Drosophila melanogaster changes in response to an exercise treatment. We find extensive variation in baseline climbing ability, and exercise-induced changes ranging from -13% to +20% in climbing ability. Climbing ability, and its exercise-induced change, are sex- and genotype-dependent. GWASs implicate "cell-cell signaling" genes in the control of climbing ability. We also find that animal activity does not predict climbing ability and that the exercise-induced climbing ability change cannot be predicted from the activity level induced by the exercise treatment. These results provide promising new avenues for further research into the molecular pathways controlling climbing activity and illustrate the complexities involved in trying to predict individual responses to exercise.

genetics↗

bioRxiv2020

GWAS reveal a role for the central nervous system in regulating weight and weight change in response to exercise

Body size and weight show considerable variation both within and between species. This variation is controlled in part by genetics, but also strongly influenced by environmental factors including diet and the level of activity experienced by the individual. Due to the increasing obesity epidemic in much of the world, there is considerable interest in the genetic factors that control body weight and how weight changes in response to exercise treatments. Here, we use GWAS in Drosophila to identify the molecular pathways that control weight and exercise-induced weight changes. We find that there is a complex set of molecular pathways controlling weight, with many genes linked to the central nervous system (CNS). Weight was strongly impacted by animal size and body composition. While the CNS appears to be important for weight and exercise-induced weight change, signaling pathways are particularly important for determining how exercise impacts weight.

genetics↗

bioRxiv2018

Genetic networks underlying natural variation in basal and induced activity levels in Drosophila melanogaster

Exercise is recommended by health professionals across the globe as part of a healthy lifestyle to prevent and/or treat the consequences of obesity. While overall, the health benefits of exercise and an active lifestyle are well understood, very little is known about how genetics impacts an individuals inclination for and response to exercise. To address this knowledge gap, we investigated the genetic architecture underlying natural variation in activity levels in the model system Drosophila melanogaster. Activity levels were assayed in the Drosophila Genetics Reference Panel 2 fly strains at baseline and in response to a gentle exercise treatment using the Rotational Exercise Quantification System. We found significant, sex-dependent variation in both activity measures and identified over 100 genes that contribute to basal and induced exercise activity levels. This gene set was enriched for genes with functions in the central nervous system and in neuromuscular junctions and included several candidate genes with known activity phenotypes such as flightlessness or uncoordinated movement. Interestingly, there were also several chromatin proteins among the candidate genes, two of which were validated and shown to impact activity levels. Thus, the study described here reveals the complex genetic architecture controlling basal and exercise-induced activity levels in D. melanogaster and provides a resource for exercise biologists.

genetics↗

bioRxiv2018

HP1B is a euchromatic Drosophila HP1 homolog with links to metabolism

Heterochromatin Protein 1 (HP1) proteins are an important family of chromosomal proteins conserved among all major eukaryotic lineages. While HP1 proteins are best known for their role in heterochromatin, many HP1 proteins function in euchromatin as well. As a group, HP1 proteins carry out diverse functions, playing roles in the regulation of gene expression, genome stability, chromatin structure, and DNA repair. While the heterochromatic HP1 proteins are well studied, our knowledge of HP1 proteins with euchromatic distribution is lagging behind. We have created the first mutations in HP1B, a Drosophila HP1 protein with euchromatic function, and the Drosophila homolog most closely related to mammalian HP1, HP1{beta}, and HP1{gamma}. We find that HP1B is a non-essential protein in Drosophila, with mutations affecting fertility and animal activity levels. In addition, animals lacking HP1B show altered food intake and higher body fat levels. Gene expression analysis of animals lacking HP1B demonstrates that genes with functions in various metabolic processes are affected primarily by HP1B loss. Our findings suggest that there is a link between the chromatin protein HP1B and the regulation of metabolism.

genetics↗