Biology subjects

Gates, D.

Publications and source records attributed to Gates, D..

5 recordsLinked to original sources

bioRxiv2026

Bacterial pyruvate metabolism regulates host insulin sensitivity in C. elegans

Two different individuals can consume an identical diet but experience different physiological outcomes. While there are many potential mechanistic reasons for this, one increasingly recognized reason is that differences in an animals microbiome can lead to differences in the processing of dietary nutrients. Thus, though a diet might start out the same, how it is experienced by a host is dependent on their microbiome. While exciting, mechanistic studies of diet-microbiome-host effects are often limited by the lack of high throughput laboratory techniques to identify and define interactions between dietary metabolites, microbial metabolism, and host biology. We hypothesized that the model organism Caenorhabditis elegans is an advantageous animal model for rapidly identifying and genetically dissecting interactions between dietary nutrients, microbial metabolism, and host physiology. Here, we used an established model of the effects of dietary glucose on insulin resistant mutant animals (daf-2/IR mutants) to study how differences in bacterial metabolism influence the consequences of dietary sugars on animal physiology. We found that the effect of dietary sugars on daf-2 mutant physiology is dependent on how the microbiome metabolizes dietary sugars. We found dietary sugar suppresses multiple daf-2 mutant phenotypes in the presence of some bacteria but has no effect in the presence of others. To determine how bacteria mediate the effects of dietary sugars on host physiology we screened 5,000 transposon mutations in the canonical C. elegans dietary bacteria, E. coli OP50 for effects on animal insulin signaling. From this, we found that the effects of exogenous sugars on the phenotype of daf-2 mutant animals is dependent on the function of pyruvate dehydrogenase in bacteria and that the loss of bacterial pyruvate dehydrogenase genes (ex. aceE) is sufficient to mimic the effects of dietary sugars on dauer formation, longevity, and gene expression in insulin signaling deficient animals. Collectively, our findings further support the growing body of evidence that the effects of dietary nutrients on animal physiology can be influenced by the gut microbiome. In addition, these studies demonstrate the advantages of the C. elegans model system for studying 3-way diet-microbiome-host interactions that are difficult to dissect in other model systems.

microbiology↗

bioRxiv2025

Oocyte mitochondria link maternal environment to offspring phenotype

During oogenesis and maturation oocytes undergo a recently discovered mitochondrial electron transport chain (ETC) remodeling in flies1, frogs1, and humans2. This conserved oocyte ETC remodeling is regulated by maternal insulin signaling, but its role in biology remains unclear. In the model animal Caenorhabditis elegans, we previously found that insulin signaling to oocytes regulates offsprings ability to adapt to future osmotic stress by altering offspring metabolism. However, the molecular mechanisms that function in oocytes to mediate this intergenerational stress response are similarly unknown. Here, we developed a low-input oocyte proteomics workflow and combined it with our C. elegans intergenerational stress response model to find that both a mothers environment and maternal insulin signaling regulate the abundance of ETC proteins in oocytes - particularly the abundance of proteins involved in the transfer of electrons from QH2 to cytochrome C by ETC Complex III. Using genetic perturbations of ETC function we further found that promoting ETC Complex III function in oocytes was both necessary and sufficient to link a mothers environment to adaptive changes in offspring metabolism. Lastly, we found that the effects of Complex III dysfunction in oocytes on offspring were mediated via an AMP-kinase (AAK-2) dependent mechanism and that AAK-2 functions in offspring to promote ATP preservation and glycerol metabolism in response to stress. Collectively, our data suggest that the role of oocyte ETC remodeling in biology includes linking maternal environments to changes in offspring metabolism that promote offspring survival in the environment experienced by their mother.

genetics↗

bioRxiv2021

Structural dynamics determine voltage and pH gating in human voltage-gated proton channel

Voltage-gated ion channels are key players of electrical signaling in cells. As a unique subfamily, voltage-gated proton (Hv) channels are standalone voltage sensors without separate ion conductive pores. They are gated by both voltage and transmembrane proton gradient (i.e {Delta}pH), serving as acid extruders in most cells. Amongst their many functions, Hv channels are known to regulate the intracellular pH of human spermatozoa and compensate for the charge and pH imbalances caused by NADPH oxidases in phagocytes. Like the canonical voltage sensors, the Hv channel is a bundle of 4 helices (named S1 through S4), with the S4 segment carrying 3 positively charged Arg residues. Extensive structural and electrophysiological studies on voltage-gated ion channels generally agree on an outwards movement of the S4 segment upon activating voltage, but the real time conformational transitions are still unattainable. With purified human voltage-gated proton (hHv1) channel reconstituted in liposomes, we have examined its conformational dynamics at different voltage and pHs using the single molecule fluorescence resonance energy transfer (smFRET). Here we provided the first glimpse of real time conformational trajectories of the hHv1 voltage sensor and showed that both voltage and pH gradient shift the conformational dynamics of the S4 segment to control channel gating. Our results suggested the biological gating is determined by the conformational distributions of the hHv1 voltage sensor, rather than the conformational transitions between the presumptive resting and activated conformations. We further identified H140 as the key residue sensing extracellular pH and showed that both the intracellular and extracellular pH sensors act on the voltage sensing S4 segment to enrich the resting conformations. Taken together, we proposed a model that explains the mechanisms underlying voltage and pH gating in Hv channels, which may also serve as a general framework to understand the voltage sensing and gating in other voltage-gated ion channels.

biophysics↗

bioRxiv2021

Selective sorting of ancestral introgression in maize and teosinte along an elevational cline

While often deleterious, hybridization can also be a key source of genetic variation and pre-adapted haplotypes, enabling rapid evolution and niche expansion. Here we evaluate these opposing selection forces on introgressed ancestry between maize (Zea mays ssp. mays) and its wild teosinte relative, mexicana (Zea mays ssp. mexicana). Introgression from ecologically diverse teosinte may have facilitated maizes global range expansion, in particular to challenging high elevation regions (> 1500 m). We generated low-coverage genome sequencing data for 348 maize and mexicana individuals to evaluate patterns of introgression in 14 sympatric population pairs, spanning the elevational range of mexicana, a teosinte endemic to the mountains of Mexico. While recent hybrids are commonly observed in sympatric populations and mexicana demonstrates fine-scale local adaptation, we find that the majority of mexicana ancestry tracts introgressed into maize over 1000 generations ago. This mexicana ancestry seems to have maintained much of its diversity and likely came from a common ancestral source, rather than contemporary sympatric populations, resulting in relatively low FSTbetween mexicana ancestry tracts sampled from geographically distant maize populations. Introgressed mexicana ancestry in maize is reduced in lower-recombination rate quintiles of the genome and around domestication genes, consistent with pervasive selection against introgression. However, we also find mexicana ancestry increases across the sampled elevational gradient and that high introgression peaks are most commonly shared among high-elevation maize populations, consistent with introgression from mexicana facilitating adaptation to the highland environment. In the other direction, we find patterns consistent with adaptive and clinal introgression of maize ancestry into sympatric mexicana at many loci across the genome, suggesting that maize also contributes to adaptation in mexicana, especially at the lower end of its elevational range. In sympatric maize, in addition to high introgression regions we find many genomic regions where selection for local adaptation maintains steep gradients in introgressed mexicana ancestry across elevation, including at least two inversions: the well-characterized 14 Mb Inv4m on chromosome 4 and a novel 3 Mb inversion Inv9f surrounding the macrohairless1 locus on chromosome 9. Most outlier loci with high mexicana introgression show no signals of sweeps or local sourcing from sympatric populations and so likely represent ancestral introgression sorted by selection, resulting in correlated but distinct outcomes of introgression in different contemporary maize populations. Author SummaryWhen species expand their ranges, new encounters with diverse wild relatives can introduce deleterious genetic variation, but may also accelerate the colonization of novel environments by providing ready-made genetic adaptations. Maize today is a global staple, far exceeding the original ecological niche of its wild progenitor. We show that gene flow from highland-endemic wild mexicana facilitated maizes range expansion from the valleys where it was domesticated to sites over 1500m in the mountains of Mexico. We find loci where mexicana ancestry has been repeatedly favored in highland maize populations. We also find loci (including a newly identified inversion) where mexicana ancestry increases steeply with elevation, providing evidence for adaptive trade-offs. We additionally demonstrate selection against mexicana ancestry, especially near domestication genes. We sampled mexicana growing alongside maize fields, yet find little evidence that introgression is recent or locally-sourced genomewide or at adaptive loci. Rather, the majority of mexicana ancestry was introduced into maize over 1000 generations ago, and subsequently diverged and was sorted by selection in individual populations. These results add to our understanding of the effects of introgression on range expansions and adaptation.

evolutionary biology↗

bioRxiv2019

Gene regulatory effects of a large chromosomal inversion in highland maize

Chromosomal inversions play an important role in local adaptation. Inversions can capture multiple locally adaptive functional variants in a linked block by repressing recombination. However, this recombination suppression makes it difficult to identify the genetic mechanisms that underlie an inversions role in adaption. In this study, we explore how large-scale transcriptomic data can be used to dissect the functional importance of a 13 Mb inversion locus (Inv4m) found almost exclusively in highland populations of maize (Zea mays ssp. mays). Inv4m introgressed into highland maize from the wild relative Zea mays ssp. mexicana, also present in the highlands of Mexico, and is thought to be important for the adaptation of these populations to cultivation in highland environments. First, using a large publicly available association mapping panel, we confirmed that Inv4m is associated with locally adaptive agronomic phenotypes, but only in highland fields. Second, we created two families segregating for standard and inverted haplotypess of Inv4m in a isogenic B73 background, and measured gene expression variation association with Inv4m across 9 tissues in two experimental conditions. With these data, we quantified both the global transcriptomic effects of the highland Inv4m haplotype, and the local cis-regulatory variation present within the locus. We found diverse physiological effects of Inv4m, and speculate that the genetic basis of its effects on adaptive traits is distributed across many separate functional variants. Author SummaryChromosomal inversions are an important type of genomic structural variant. However, mapping causal alleles within their boundaries is difficult because inversions suppress recombination between homologous chromosomes. This means that inversions, regardless of their size, are inherited as a unit. We leveraged the high-dimensional phenotype of gene expression as a tool to study the genetics of a large chromosomal inversion found in highland maize populations in Mexico - Inv4m. We grew plants carrying multiple versions of Inv4m in a common genetic background, and quantified the transcriptional reprogramming induced by alternative alleles at the locus. Inv4m has been shown in previous studies to have a large effect on flowering, but we show that the functional variation within Inv4m affects many developmental and physiological processes. Author ContributionsT. Crow, R. Rellan-Alvarez, R. Sawers and D. Runcie conceived and designed the experiment. M. Aguilar-Rangel, J. Rodr[g]uez, R. Rellan-Alvarez and R. Sawers generated the segregating families. T. Crow, J. Ta, S. Nojoomi, M. Aguilar-Rangel, J. Rodr[g]uez D. Gates, D. Runcie performed the experiment. T. Crow, D. Gates, D. Runcie analyzed the data. T. Crow, D. Runcie wrote the original manuscript, and R. Rellan-Alvarez and R. Sawers provided review and editing.

genomics↗