Biology subjects

English, S.

Publications and source records attributed to English, S..

9 recordsLinked to original sources

bioRxiv2026

Heat exposure and adverse pregnancy outcomes: evidence from humans and other viviparous species

Introduction: With global warming, heatwaves are increasing in severity, affecting species worldwide. Recent studies show associations between heat exposure in pregnancy and adverse birth outcomes such as preterm birth, low birthweight and stillbirth across multiple species. This suggests potentially conserved mechanisms such as maternal inflammation, dehydration and changes in placental physiology in response to heat exposure. Moreover, the gestational timing of antenatal heat likely impacts the type and severity of outcome, yet this is not fully understood. Methods: We conducted a scoping review of studies on heat exposure and pregnancy outcomes in humans and other animals, to identify common mechanisms and temporal dynamics of effects. Temperature-, trimester- and species- specific patterns were reviewed across 197 studies and ten species (human, cow, sheep, pig, goat, rat, mouse, guinea pig, lizard and rabbit). Results: Qualitative trends indicate that high temperatures are associated with adverse birth outcomes. In particular, third trimester exposure increases risk of preterm birth and low birthweight. Many studies emphasise placental involvement in adverse outcomes and point to potential aberrations in placental physiology or cortisol signaling pathways. Conclusions: Overall, literature presents that heat exposure increases risk of adverse birth outcomes across studies, and taxa. Understanding the relationship between heat exposure and adverse birth outcomes, as well as the mechanisms and timing, is vital for informing public health policies and creating mitigating strategies for expecting mothers.

physiology↗

bioRxiv2026

Extended pregnancy during matrotrophy in cockroaches increases progeny survival during dry periods

Animals reproduce across a spectrum from oviparity to viviparity. Internal gestation and live birth have inherent advantages despite their costs. However, comparative analyses of key drivers, such as resilience to dehydration, lack taxonomic breadth. In this study, we assessed whether live birth improves the ability to proliferate in environments with limited access to water. To do so, we used the viviparous cockroach, Diploptera punctata, as a model of viviparity to assess dehydration-induced damage during extended periods of water deprivation. During pregnancy, maternal survival did not decline during dry periods compared with non-pregnant individuals, suggesting that pregnancy has minimal impact on resistance to dehydration stress. When mothers are deprived of water for 2 weeks, they show an increase in osmolality after one week, while their embryos show no change in osmolality until after two weeks, at which point abortions occur. Periods of dehydration increased the duration of pregnancy, likely due to a slower production of in utero milk, but there was no change in the size of progeny. After birth, viviparous D. punctata newborns showed increased survival under dry conditions compared to two other ovoviviparous species, which are much smaller and dehydrate more quickly. The combined impact of increased dehydration resistance during pregnancy and during the first independent phase indicates a benefit of prolonged viviparity in Diploptera punctata. This study provides evidence that viviparity in animal systems could enable progeny survival during drought.

ecology↗

bioRxiv2026

Novel quantitative trait loci conferring broad-based resistance to root-knot nematodes in lima bean (Phaseolus lunatus)

Lima bean (Phaseolus lunatus) is a broadly adapted, economically important leguminous crop and a susceptible host of root-knot nematodes (Meloidogyne spp.; RKN), which are a devastating plant pathogen in agricultural systems worldwide. To date, there have been few studies to elucidate the genetic determinants of RKN resistance in lima beans. Understanding the genetic mechanisms underlying resistance is essential for improving resistance traits and incorporating them into lima bean breeding programs. To assist in marker-assisted selection, we aimed to identify and map quantitative trait loci (QTLs) conferring RKN resistance-related traits. Three recombinant inbred line (RIL) populations were used in this study. Three populations were derived by crossing two RKN-resistant parents with the same RKN-susceptible parent and with each other. All populations were genotyped using genome-wide single-nucleotide polymorphism (SNP) markers. Each population was screened for root galling (RG) and RKN egg reproduction (ER) in response to M. incognita and M. javanica in greenhouse experiments. Three major QTLs were detected and mapped on chromosome Pl04 (QRk-pl04.1), Pl05 (QRk-pl05.1) and Pl10 (QRk-pl10.1) across populations. Among them, QRk-pl05.1 and QRk-pl10.1 affected levels of RG and ER of both RKN species, while QRk-pl04.1 suppressed root galling and reproduction responses of M. incognita but not of M. javanica. These chromosomal regions defined by flanking markers will help guide marker-assisted breeding and gene discovery for broad-based RKN resistance in lima beans.

plant biology↗

bioRxiv2025

A domestication change at PvMYB26 in common bean sheds light on the origins of Middle American agriculture

Domestication imposed radically different selection pressures on plants, eventually transforming them into the cultivated forms that support global populations today. Here, we investigate the loss of seed dispersal via pod shattering during common bean (Phaseolus vulgaris L.) domestication. We identified an eight-kb deletion eliminating the transcription start site and promoter of the candidate gene PvMYB26. Mutants express PvMYB26 at < 1% of the level of wild types and produce 44% less pod lignin. Whole-genome sequencing revealed that the mutation is nearly diagnostic for domestication status among Middle American common bean, indicating its importance in domestication. We also identified a high-frequency PvMYB26 frameshift/premature stop mutation unique to Andean domesticates. Wild haplotypes most like Middle American domesticates are found in eastern Jalisco, Mexico. Our results suggest that West-Central Mexico was the site of common bean domestication and suggest that this region may have been important in the rise of Middle American agriculture.

evolutionary biology↗

bioRxiv2025

Daily activity rhythms, sleep, and pregnancy are fundamentally related in the Pacific beetle mimic cockroach, Diploptera punctata

Sleep and pregnancy are contentious bedfellows; sleep disorders and disturbances are associated with adverse pregnancy outcomes, although much is still unknown about this relationship. Sleep and pregnancy have been studied in many models, but most focus heavily on mammals. However, pregnancy is ubiquitous across the animal kingdom - a hallmark of convergent evolution; similarly sleep is a shared feature across diverse species. Here, we present an ideal model in which to study the dynamics between sleep and pregnancy in invertebrates. The Pacific beetle mimic cockroach, Diploptera punctata, is a viviparous cockroach species that uses milk proteins to nourish its young with a broodsac over a three month pregnancy. However, little is known about the relationship between this unique reproductive biology and daily rhythms of activity and sleep. We established that D. punctata displayed a peak in activity shortly following sunset, with males significantly more active than females. When scavenging behavior was examined, males and non-pregnant females emerged more often and traveled further from a shelter compared to pregnant females, suggesting reduced risk-taking behavior in late pregnancy. Chronic disturbance of sleep during pregnancy negatively impacted embryo development by increasing gestational duration and decreasing the transcription of milk proteins. These findings indicate that sleep is key to embryo development and that pregnancy has a significant impact on the daily rhythms of activity in Diploptera punctata. More broadly, we present a tractable invertebrate model for understanding the relationship between sleep and pregnancy, which will aid in the exploration of the poorly understood interface between these two ubiquitous and highly conserved traits.

physiology↗

bioRxiv2024

How does host age and nutrition affect density regulation of obligate versus facultative bacterial symbionts? Insights from the tsetse fly

The relationships between insect hosts and their symbionts can vary tremendously in the extent to which hosts depend on and control their symbionts. Obligate symbionts that provide micronutrients to their host are often compartmentalised to specialised host organs and depend on their hosts for survival, whereas facultative symbionts retain the ability to survive outside of their hosts. Few studies compare the extent to which a host controls and adjusts the density of obligate and facultative symbionts directly. Here, we used tsetse as a model for teasing apart the relationships between a host (Glossina morsitans morsitans) and obligate (Wigglesworthia glossinidia) and facultative (Sodalis glossinidius) symbionts. We hypothesised that tsetse actively regulate the density of Wigglesworthia according to the hosts requirements, depending on their current nutritional state and developmental age. In contrast, we postulated that Sodalis retains some independence from host control, and that the growth of this symbiont is dependent on the conditions of the immediate environment, such as nutrient availability. Using qPCR, we examined how symbiont densities change across host age and the hunger cycle. Additionally, we investigated how host nutrition influences symbiont density, by comparing tsetse that were fed diluted blood (poor nutrition) or blood supplemented with yeast extract (vitamin enriched). We found that the density of Wigglesworthia did not reflect the nutritional status of the host, but was optimised to accommodate long-term host requirements (in terms of nutrient provisioning). In contrast, the density of facultative Sodalis was influenced by the ecological context (i.e. nutrient availability). This suggests that tsetse regulate the abundance of Wigglesworthia to a greater extent than Sodalis. We propose that tsetse exert only partial control over Sodalis growth due to the relatively recent transition of this symbiont to host-associated living. Author summarySymbiotic microbes have the potential to significantly impact the wider ecosystem by affecting the fitness and behaviour of their animal hosts. The density of a particular symbiont population within host tissues is likely an important factor influencing the effect it has on the host, however, little is known about the factors which determine how symbiont density is regulated, and how these differ between symbionts with different degrees of host-association (e.g. obligate and facultative symbionts). Here, we found that Wigglesworthia and Sodalis, two bacterial tsetse symbionts, demonstrate distinct trends in density according to host age and nutrition. We discuss how the evolutionary histories of these symbionts with their host potentially explain these results, highlighting the complexity and dynamic nature of host-symbiont interactions. Our findings contribute to our understanding of the extent to which hosts and symbionts control symbiont density and how symbiont density regulation can be affected by the ecological context.

evolutionary biology↗

bioRxiv2022

Structure of trimeric pre-fusion rabies virus glycoprotein in complex with two protective antibodies

Rabies virus (RABV) causes lethal encephalitis and is responsible for approximately 60,000 deaths per year. As the sole virion-surface protein, the rabies virus glycoprotein (RABV-G) mediates host-cell entry. RABV-Gs pre-fusion trimeric conformation displays epitopes bound by protective neutralizing antibodies which can be induced by vaccination or passively administered for post-exposure prophylaxis. We report a 2.8-[A] structure of a RABV-G trimer in the pre-fusion conformation, in complex with two neutralizing and protective monoclonal antibodies, 17C7 and 1112-1. One of these antibodies is a licensed prophylactic (17C7, Rabishield), which we show locks the protein in pre-fusion conformation. We demonstrate that targeted mutations can stabilize RABV-G in the pre-fusion conformation, a key step towards structure-guided vaccine design. These data reveal the higher-order architecture of a key therapeutic target and the structural basis of neutralization by antibodies binding two key antigenic sites, and will facilitate the development of improved vaccines and prophylactic antibodies.

microbiology↗

bioRxiv2022

Live-bearing cockroach genome reveals convergent evolutionary mechanisms linked to viviparity in insects and beyond

Insects provide an unparalleled opportunity to link genomic changes with the rise of novel phenotypes, given tremendous variation in the numerous and complex adaptations displayed across the group. Among these numerous and complex adaptations, live-birth has arisen repeatedly and independently in insects and across the tree of life, suggesting this is one of the most common types of convergent evolution among animals. We sequenced the genome and transcriptome of the Pacific beetle-mimic cockroach, the only truly viviparous cockroach, and performed comparative analyses including two other viviparous insect lineages, the tsetse and aphids, to unravel the genomic basis underlying the transition to viviparity in insects. We identified pathways experiencing adaptive evolution, common in all viviparous insects surveyed, involved in uro-genital remodeling, maternal control of embryo development, tracheal system, and heart development. Our findings suggest the essential role of those pathways for the development of placenta-like structure enabling embryo development and nutrition. Viviparous transition seems also to be accompanied by the duplication of genes involved in eggshell formation. Our findings from the viviparous cockroach and tsetse reveal that genes involved in uterine remodeling are up-regulated and immune genes are down-regulated during the course of pregnancy. These changes may facilitate structural changes to accommodate developing young and protect them from the mothers immune system. Our results denote a convergent evolution of live-bearing in insects and suggest similar adaptive mechanisms occurred in vertebrates, targeting pathways involved in eggshell formation, uro-genital remodeling, enhanced tracheal and heart development, and reduced immunity.

genomics↗

bioRxiv2021

Differential transcriptomic response of Anopheles arabiensis to Plasmodium vivax and Plasmodium falciparum infection

Plasmodium vivax malaria is now recognized as the second most dangerous parasitic threat to human health with the regular decrease of Plasmodium falciparum worldwide over recent decades. A very limited numbers of studies address the interaction of P. vivax with its Anopheles mosquito vectors. Those studies were conducted in P. vivax endemic countries with P.vivax local major vectors for which limited genomic and genetic tools are available. Despite the presence of P. vivax in several African countries and increasing reports on its occurrence in many others, there is virtually no data on the molecular responses of Anopheles arabiensis, a major African mosquito vector, to P. vivax, which limits the development of further "mosquito-targeted" interventions aimed at reducing P. vivax transmission. Taking advantage of the situation of Madagascar where P. falciparum, P. vivax and An. arabiensis are present, we explore the molecular responses of An. arabiensis towards these two human malaria parasites. RNA sequencing on RNAs isolated from mosquito midguts dissected at the early stage of infection (24 hours) was performed using mosquitoes fed on the blood of P. vivax and P. falciparum gametocyte carriers in a field station. From a de novo assembly of An. arabiensis midgut total RNA transcriptome, the comparative analysis revealed that a greater number of genes were differentially expressed in the mosquito midgut in response to P. vivax (209) than to P. falciparum (81). Among these, 15 common genes were identified to be significantly expressed in mosquito midgut 24 hours after ingesting P. vivax and P. falciparum gametocytes, including immune responsive genes and genes involved in amino-acid detoxification pathways. Importantly, working with both wild mosquitoes and field circulating parasites, our analysis revealed a strong mosquito genotype by parasite genotype interaction. Our study also identified 51 putative long non-coding RNAs differentially expressed in An. arabiensis mosquito infected midgut. Among these, several mapped to the published An. arabiensis genome at genes coding immune responsive genes such as gambicin 1, leucine-rich repeat containing genes, either on sense or antisense strands. This study constitutes the first comparison of An. arabiensis molecular interaction with P. vivax and P. falciparum, investigating both coding and long non-coding RNAs for the identification of potential transcripts, that could lead to the development of novel approaches to simultaneously block the transmission of vivax and falciparum malaria.

microbiology↗