Biology subjects

Edwards, J. L.

Publications and source records attributed to Edwards, J. L..

3 recordsLinked to original sources

bioRxiv2023

Dissecting an ancient stress resistance trait syndrome in the compost yeast Kluyveromyces marxianus

Organisms specialized to extreme environments can be the product of millions of years of evolutionary engineering and refinement. The underlying genetics can be quite distinct from the ones operating at earlier stages of trait innovation. In this work, we have developed the multi-stress resistant yeast Kluyveromyces marxianus, which diverged from its closest relative >20 million years ago, as a model for interspecies comparative biology and genomics. In growth assays of the Kluyveromyces genus, we found that K. marxianus exhibited unique tolerance of high heat and a subset of chemical stress conditions. We then generated and analyzed omic profiles from across the genus to find molecular features associated with- and potentially causal for - K. marxianus traits. Expression profiling revealed divergent lipid processing and membrane transport programs in K. marxianus, borne out in changes in lipid utilization in experimental assays. Sequence analyses found robust evidence for expansions in gene families in the K. marxianus genome, most notably among transmembrane transporters and in metabolic enzymes. In molecular-evolution tests, we identified adaptive protein variants throughout the K. marxianus genome among which plasma membrane transporters were over-represented. These data enable a model of the molecular mechanisms and evolutionary pressures underlying K. marxianus traits, including adaptive changes to transporters, lipid processing, and membrane functions mediating stress resistance. Significance statementMany traits of basic and applied interest arose long ago and manifest in the modern day as fixed in a given species; understanding how evolution built them, potentially over millions of years, remains a key challenge in the field. In this study, we report stress-resistance phenotypes that distinguish the yeast Kluyveromyces marxianus from its relatives, and we discover unique patterns of genetic and regulatory variation in membrane-protein genes, as well as unique properties of lipid metabolism, in this species. We propose a broadly applicable model in which evolution can tune membrane lipid composition and membrane-protein function to boost cellular fitness in challenging environments.

evolutionary biology↗

bioRxiv2022

Physiological Levels of Estrogen and Progesterone Modulate CR3 expression on, and Neisseria gonorrhoeae Infection of, Primary, Human, Cervical Epithelial Cells

Despite advances made in our understanding of Neisseria gonorrhoeae pathogenesis, factors dictating the divergent presentation of gonococcal disease observed between men and women, in vivo, remain unclear. Clinical data indicate that gonococcal pathogenesis of the female genital tract is influenced by steroid hormones. Notwithstanding, there are limited data addressing how steroid hormones modulate gonococcal pathogenesis. Hence, we investigated the effect(s) of physiological concentrations of estrogens and progestogens on N. gonorrhoeae viability and on complement-mediated infection of primary cervical cells. In contrast to previous studies that showed a bacteriostatic effect of non-physiological concentrations of steroid hormones on gonococci, our data indicate that physiological concentrations of estrogens and progestogens do not inhibit gonococcal growth in vitro or during infection of primary cervical cells. Estradiol promoted complement receptor 3 recruitment to the cervical cell surface and, thus, the ability of gonococci to associate with these cells. Progesterone-predominant assay conditions resulted in decreased expression of Opa proteins by gonococci, increased complement production by cervical cells, and increased iC3b opsonization of gonococci during cervical cell challenge. Collectively, our data support clinical observations and demonstrate that estrogens and progestogens distinctly modulate gonococcal cervical infection.

microbiology↗

bioRxiv2020

Capturing in-field root system dynamics with the RootTracker

Optimizing root system architecture offers a promising approach to developing stress tolerant cultivars in the face of climate change, as root systems are critical for water and nutrient uptake as well as mechanical stability. However, breeding for optimal root system architecture has been hindered by the difficulty in measuring root growth in the field. Here, we describe a technology, the RootTracker (RT), which employs capacitance touch sensors to monitor in-field root growth over time. Configured in a cylindrical shutter-like fashion around a planted seed, 264 electrodes are individually charged multiple times over the course of an experiment. Signature changes in the measured capacitance and resistance readings indicate when a root has touched or grown close to an electrode. Using the RootTracker, we have measured root system dynamics of commercial maize hybrids growing in both typical Midwest field conditions and under different irrigation regimes. We observed rapid responses of root growth to water deficits and found evidence for a "priming response" in which an early water deficit causes more and deeper roots to grow at later time periods. There was genotypic variation among hybrid maize lines in their root growth in response to drought, indicating a potential to breed for root systems adapted for different environments.

plant biology↗