Biology subjects

Sinha, R.

Publications and source records attributed to Sinha, R..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Defining the limits of differential transpiration

Differential transpiration is a newly discovered acclimation strategy of annual plants to a combination of water deficit (WD) and heat stress (HS). Under these conditions (i.e., WD+HS), transpiration of vegetative tissues is suppressed in plants such as soybean and tomato, while transpiration of reproductive tissues is not (termed Differential Transpiration; DT). This newly discovered acclimation process enables the cooling of reproductive organs under conditions of WD+HS, limiting HS-induced damage to plant reproduction. However, at what temperature and WD extremes will this process be active and functional at reducing the internal temperature of reproductive tissues, and at what developmental stages of the plant is it activated, remain unknown. Here, we report that DT occurs at most nodes (leaf developmental stages) of soybean plants subjected to WD+HS, and that it can function under extreme conditions of WD+HS (i.e., 18% of field water capacity and 42{degrees}C combined). Our findings reveal that DT is an effective acclimation strategy that protects reproductive processes from extreme conditions of WD+HS, at almost all developmental stages. In addition, our findings suggest that under field conditions DT could also be active in plants subjected to low or mild levels of WD during a heat wave.

plant biology↗

bioRxiv2024

Carbapenem-Resistant Enterobacter hormaechei Uses Mucus Metabolism to Facilitate Gastrointestinal Colonization

The emergence and global spread of carbapenem-resistant Enterobacter cloacae complex species presents a pressing public health challenge. Carbapenem-resistant Enterobacter species cause a wide variety of infections, including septic shock fatalities in newborns and immunocompromised adults. The intestine may be a major reservoir for these resistant strains, either by facilitating contamination of fomites and transfer to susceptible individuals, or through translocation from the gut to the bloodstream. For this reason, we sought to establish a neonatal mouse model to investigate the mechanisms underpinning gut colonization by carbapenem-resistant Enterobacter hormaechei. We describe a new mouse model to study gut colonization by Enterobacter species, leading to vital insights into the adaptation of carbapenem-resistant E. hormaechei to the gut environment during the early stages of intestinal colonization. We observed successful colonization and proliferation of E. hormaechei in the five-day old infant mouse gut, with primary localization to the colon following oral inoculation. We also uncovered evidence that E. hormaechei uses mucus as a carbon source during colonization of the colon. Our findings underscore the importance of oxygen-dependent metabolic pathways, including the pyruvate dehydrogenase complex, and N-acetyl-D-glucosamine metabolism, in gut colonization and proliferation, which aligns with previous human studies. These insights are essential for developing novel therapeutic strategies that can serve as decolonization therapies in at-risk populations. ImportanceBloodstream infections caused by Enterobacter species pose a significant clinical threat. The intestine acts as the primary site for colonization and serves as a reservoir for infection. To combat this pathogen, it is crucial to understand how carbapenem-resistant Enterobacter species colonize the gut, as such knowledge can pave the way for alternative therapeutic targets. In this study, we developed a novel neonatal mouse model for gastrointestinal colonization by Enterobacter species and discovered that mucus plays a key role as a carbon source during colonization. Additionally, we identified two mucus catabolism pathways that contribute to intestinal colonization by carbapenem-resistant E. hormaechei. This new mouse model offers valuable insights into host-pathogen interactions and helps identify critical gastrointestinal fitness factors of Enterobacter, potentially guiding the development of vaccines and alternative therapeutic strategies to minimize intestinal carriage in patient populations at risk for infection with Enterobacter species.

microbiology↗

bioRxiv2024

A novel method for integrating genomic and Tn-Seq data to identify common in vivo fitness mechanisms across multiple bacterial species

Sepsis is life-threatening organ dysfunction due to an unregulated immune response to infection. Bacteremia is a leading cause of sepsis, and members of the Enterobacterales cause nearly half of bacteremia cases annually. While previous Tn-Seq studies to identify novel bacteremia-fitness genes have provided valuable insight into virulence mechanisms, evidence for common pathways across species is lacking. To identify common fitness pathways in five bacteremia- caused Enterobacterales species, we utilized the JCVI pan-genome pipeline to integrate Tn-Seq fitness data with multiple available functional data types. Core genes from species pan-genomes were used to construct a multi-species core pan-genome, producing 2,850 core gene clusters found in four out of the five species. Integration of Tn-Seq fitness data enabled identification of 373 protein clusters that were conserved in all five species. A scoring rubric and filter was applied to these clusters, which incorporated Tn-Seq fitness defects, operon localization, and antibiotic susceptibility data, which reduced the number of bacteremia-fitness genes and identified seven common fitness mechanisms. Independent mutational validation of one prioritized fitness gene, tatC, showed reduced fitness in vivo and increased susceptibility to beta- lactams that were restored following tatC complementation in trans. By integrating known operon structures and antibiotic susceptibility with Tn-Seq fitness data, common genes within the core pan-genome emerged and revealed mechanisms that are essential for colonization of, or survival in, the mammalian bloodstream. Our prediction and validation of tatC as a common bacteremia fitness factor and contributor of antibiotic resistance supports the utility of this bioinformatic approach. This study represents a major step forward to prioritize potentially novel targets for therapy against these deadly widespread sepsis infections. Author SummaryBacteremia is a leading cause of sepsis, a life-threatening condition where an unregulated immune response to infection causes systemic organ failure. Nearly half of bacteremia cases are caused by members of the Gram-negative bacterial taxonomic order Enterobacterales. Given the public health impact of bacteremia and the reduction of existing antibiotic treatment options, novel strategies are needed to combat these infections. Pan-genome software was used to predict seven shared fitness pathways in these bacteria that may serve as novel targets for treatment of bacteremia. Briefly, a scoring rubric was applied to shared pan-genome clusters, which incorporated multiple data types, including Tn-Seq fitness defects, operon localization, and antibiotic susceptibility data to rank and prioritize fitness genes. To validate one of our predictions, mutations were constructed in tatC, which showed both reduced fitness in mice and increased susceptibility to beta-lactam antibiotics; complementation restored fitness and antibiotic susceptibility to wild type levels. This study takes a novel bioinformatics approach to build a core pan-genome across multiple distantly related bacteria to integrate computational and experimental data to predict important shared fitness genes and represents a major step forward toward identifying novel targets of therapy against these deadly widespread life-threatening infections.

bioinformatics↗

bioRxiv2024

Atlas of Cynomolgus Macaque Hematopoiesis

Self-renewal and differentiation are inherent properties of hematopoietic stem cells (HSCs) that are necessary to support hematopoiesis; however, the underlying mechanisms, especially in human, remain unclear. Here, using the cynomolgus macaque as a surrogate model, we develop a new gating strategy to isolate with high purity transplantable cynomolgus HSCs and generated a single-cell transcriptomic map of cynomolgus HSCs and progenitor cells -- that covering gestational periods previously not analyzed in human. We show that hematopoietic cells from the late-1st to early-3rd trimester fetal liver and late-2nd trimester and thereafter bone marrow have repopulating potential, closely mimicking humans. Unexpectedly however, we found unlike in human, cynomolgus HSCs express CD38 but not CD33, indicating that these cellular counterparts are molecularly distinct. Our transcriptomic analysis reveals the presence of a direct differentiation pathway from HSCs to megakaryocyte lineages, lineage-primed multipotent progenitors and also identified putative HSC surface markers. Taken together, our comprehensive dataset highlights not only the utility of cynomolgus monkeys as model systems to study hematopoiesis but also their potential for translational applications.

cell biology↗

bioRxiv2024

Engineering inducible signaling receptors to enable erythropoietin-free erythropoiesis

Blood transfusion plays a vital role in modern medicine. However, availability is contingent on donated blood, and frequent shortages pose a significant healthcare challenge. Ex vivo manufacturing of red blood cells (RBCs) derived from universal donor O-negative pluripotent stem cells emerges as a solution, yet the high cost of recombinant cytokines required for ex vivo erythroid differentiation remains a major barrier. Erythropoietin (EPO) signaling through the EPO receptor is indispensable to RBC development, and EPO is one of the most expensive components in erythroid-promoting media. Here, we used design-build-test cycles to develop highly optimized small molecule-inducible EPO receptors (iEPORs) which were integrated at a variety of genomic loci using homology-directed repair genome editing. We found that integration of iEPOR at the endogenous EPOR locus in an induced pluripotent stem cell producer line enabled culture with small molecule to yield equivalent erythroid differentiation, transcriptomic changes, and hemoglobin production compared to cells cultured with EPO. Due to the dramatically lower cost of small molecules vs. recombinant cytokines, these efforts eliminate one of the most expensive elements of ex vivo culture media--EPO cytokine. Because dependence on cytokines is a common barrier to ex vivo cell production, these strategies could improve scalable manufacturing of a wide variety of clinically relevant cell types. More broadly, this work showcases how synthetic biology and genome editing may be combined to introduce precisely regulated and tunable behavior into cells, an advancement which will pave the way for increasingly sophisticated cell engineering strategies.

synthetic biology↗

bioRxiv2024

Fitness Factor Genes Conserved within the Multi-species Core Genome of Gram-negative Enterobacterales Species Contribute to Bacteremia Pathogenesis

There is a critical gap in knowledge about how Gram-negative bacterial pathogens, using survival strategies developed for other niches, cause lethal bacteremia. Facultative anaerobic species of the Enterobacterales order are the most common cause of Gram-negative bacteremia, including Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, and Enterobacter hormaechei. Bacteremia often leads to sepsis, a life-threatening organ dysfunction resulting from an unregulated immune response to infection. Despite a lack of specialization for this host environment, Gram-negative pathogens cause nearly half of bacteremia cases annually. Based on our existing Tn-Seq fitness factor data from a murine model of bacteremia combined with comparative genomics of the five Enterobacterales species above, we prioritized 18 conserved fitness genes or operons for further characterization. Each mutant in each species was used to cochallenge C57BL/6 mice via tail vein injection along with the respective wild-type strain to determine competitive indices for each fitness gene or operon. Among the five species, we found three fitness factor genes, that when mutated, attenuated the mutant for all species in the spleen and liver (tatC, ruvA, gmhB). Nine additional fitness factor genes or operons were validated as outcompeted by wild-type in three or four bacterial species in the spleen (xerC, wzxE, arcA, prc, apaGH, atpG, lpdA, ubiH, aroC). Overall, 17 of 18 fitness factor mutants were attenuated in at least one species in the spleen or liver. Together, these findings allow for the development of a model of bacteremia pathogenesis that may include future targets of therapy against bloodstream infections. >Author SummaryFrequent cases of bacteremia plague our ICUs, bone marrow transplant units, and inpatient facilities. Nearly half of these infections are caused by Gram-negative bacteria. The Enterobacterales order including E. coli, K. pneumoniae, S. marcescens, C. freundii, and E. hormaechei are leading causes of bacteremia. An alarming proportion of these are due to antibiotic-resistant isolates, which are four times more likely to kill than antibiotic-susceptible isolates. Clearly, we need new therapeutic targets to treat cases of bacteremia and sepsis. Previously, it has been unclear what genes contribute to their ability to survive in this hostile host environment. We have previously undertaken unbiased genetic screens to identify 18 genes shared by all five bacterial genera that are required for survival in blood and blood-filtering organs. These include genes that encode proteins that maintain proton motive force, resist antimicrobial peptides and complement, mediate genome maintenance, transport key metabolites and proteins, avoid oxidative stress, acquire iron, and regulate key pathways. Mutants, constructed in these shared genes in the five species, were validated for a high proportion of genes as critical for infection in the mouse model of bacteremia.

microbiology↗

bioRxiv2023

NK and NKT cells in the pathogenesis of Hidradenitis suppurativa: Novel therapeutic strategy through targeting of CD2

Hidradenitis suppurativa (HS) is a chronic debilitating inflammatory skin disease with poorly understood pathogenesis. Single-cell RNAseq analysis of HS lesional and healthy individual skins revealed that NKT and NK cell populations were greatly expanded in HS, and they expressed elevated CD2, an activation receptor. Immunohistochemistry analyses confirmed significantly expanded numbers of CD2+ cells distributed throughout HS lesional tissue, and many co-expressed the NK marker, CD56. While CD4+ T cells were expanded in HS, CD8 T cells were rare. CD20+ B cells in HS were localized within tertiary follicle like structures. Immunofluorescence microscopy showed that NK cells (CD2+CD56dim) expressing perforin, granzymes A and B were enriched within the hyperplastic follicular epidermis and tunnels of HS and juxtaposed with apoptotic cells. In contrast, NKT cells (CD2+CD3+CD56bright) primarily expressed granzyme A and were associated with -SMA expressing fibroblasts within the fibrotic regions of the hypodermis. Keratinocytes and fibroblasts expressed high levels of CD58 (CD2 ligand) and they interacted with CD2 expressing NKT and NK cells. The NKT/NK maturation and activating cytokines, IL-12, IL-15 and IL-18, were significantly elevated in HS. Inhibition of cognate CD2-CD58 interaction with blocking anti-CD2 mAb in HS skin organotypic cultures resulted in a profound reduction of the inflammatory gene signature and secretion of inflammatory cytokines and chemokines in the culture supernate. In summary, we show that a cellular network of heterogenous NKT and NK cell populations drives inflammation, tunnel formation and fibrosis in the pathogenesis of HS. Furthermore, CD2 blockade is a viable immunotherapeutic approach for the management of HS.

immunology↗

bioRxiv2023

Light-adaptation clamp: a tool to predictably manipulate photoreceptor light responses

Computation in neural circuits relies on the judicious use of nonlinear circuit components. In many cases, multiple nonlinear components work collectively to control circuit outputs. Separating the contributions of these different components is difficult, and this limits our understanding of the mechanistic basis of many important computations. Here, we introduce a tool that permits the design of light stimuli that predictably alter rod and cone phototransduction currents - including stimuli that compensate for nonlinear properties such as light adaptation. This tool, based on well-established models for the rod and cone phototransduction cascade, permits the separation of nonlinearities in phototransduction from those in downstream circuits. This will allow, for example, direct tests of how adaptation in rod and cone phototransduction affects downstream visual signals and perception.

neuroscience↗

bioRxiv2023

Gut metabolite L-lactate supports Campylobacter jejuni population expansion during acute infection

How the microaerobic pathogen Campylobacter jejuni establishes its niche and expands in the gut lumen during infection is poorly understood. Using six-week-old ferrets as a natural disease model, we examined this aspect of C. jejuni pathogenicity. Unlike mice, which require significant genetic or physiological manipulation to become colonized with C. jejuni, ferrets are readily infected without the need to disarm the immune system or alter the gut microbiota. Disease after C. jejuni infection in ferrets reflects closely how human C. jejuni infection proceeds. Rapid growth of C. jejuni and associated intestinal inflammation was observed within two-three days of infection. We observed pathophysiological changes that were noted by cryptic hyperplasia through the induction of tissue repair systems, accumulation of undifferentiated amplifying cells on the colon surface, and instability of HIF-1 in colonocytes, which indicated increased epithelial oxygenation. Metabolomic analysis demonstrated that lactate levels in colon content were elevated in infected animals. A C. jejuni mutant lacking lctP, which encodes an L-lactate transporter, was significantly decreased for colonization during infection. Lactate also influences adhesion and invasion by C. jejuni to a colon carcinoma cell line (HCT116). The oxygenation required for expression of lactate transporter (lctP) led to discovery of a putative thiol based redox switch regulator (LctR) that may repress lctP transcription under anaerobic conditions. Our work provides new insights into the pathogenicity of C. jejuni. SignificanceThere is a gap in knowledge about the mechanisms by which C. jejuni populations expand during infection. Using an animal model which accurately reflects human infection without the need to alter the host microbiome or the immune system prior to infection, we explored pathophysiological alterations of the gut after C. jejuni infection. Our study identified the gut metabolite L-lactate as playing an important role as a growth substrate for C. jejuni during acute infection. We identified a DNA binding protein, LctR, that binds to the lctP promoter and may repress lctP expression, resulting in decreased lactate transport under low oxygen levels. This work provides new insights about C. jejuni pathogenicity.

microbiology↗

bioRxiv2023

Augmenting complex and dynamic performance through mindfulness-based cognitive training: an evaluation of training adherence, trait mindfulness, personality and resting-state EEG.

Human performance applications of mindfulness-based training have demonstrated its utility in enhancing cognitive functioning. Previous studies have illustrated how these interventions can improve performance on traditional cognitive tests, however, little investigation has explored the extent to which mindfulness-based training can optimise performance in more dynamic and complex contexts. Further, from a neuroscientific perspective, the underlying mechanisms responsible for performance enhancements remain largely undescribed. With this in mind, the following study aimed to investigate how a short-term mindfulness intervention (one week) augments performance on a dynamic and complex task (target motion analyst task; TMA) in young, healthy adults (n = 40, age range = 18 - 38). Linear mixed effect modelling revealed that increased adherence to the mindfulness-based training regime (ranging from 0-21 sessions) was associated with improved performance in the second testing session of the TMA task, controlling for baseline performance. Further analyses of resting-state electroencephalographic (EEG) metrics and additional individual factors demonstrated enhancements associated with training adherence remained relatively consistent across varying levels of participants resting-state EEG metrics, personality measures (i.e., trait mindfulness, neuroticism, conscientiousness), self-reported enjoyment and timing of intervention adherence. Our results thus indicate that mindfulness-based cognitive training leads to performance enhancements in distantly related tasks, irrespective of several individual differences. We also revealed nuances in the magnitude of cognitive enhancements contingent on the timing of adherence, regardless of total volume of training. Overall, our findings suggest that mindfulness-based training could be used in a myriad of settings to elicit transferable performance enhancements.

neuroscience↗

bioRxiv2023

Integrative phenotypic-transcriptomic analysis of soybean plants subjected to multifactorial stress combination

Global warming, climate change, and industrial pollution are altering our environment subjecting crops to an increasing number and complexity of abiotic stress conditions, concurrently or sequentially. Recent studies revealed that a combination of 3 or more stresses simultaneously impacting a plant (termed multifactorial stress combination; MFSC) can cause a drastic decline in plant growth and survival, even if the level of each stress involved in the MFSC has a negligible effect on plants. However, the impacts of MFSC on crops are largely unknown. We subjected soybean plants to a MFSC of up to five different stresses (water deficit, salinity, low phosphate, acidity, and cadmium), in an increasing level of complexity, and conducted integrative transcriptomic-phenotypic analysis of reproductive and vegetative tissues. We reveal that MFSC has a negative cumulative effect on soybean yield, that each set of MFSC condition elicits a unique transcriptomic response (that is different between flowers and leaves), and that selected genes expressed in leaves or flowers are linked to the effects of MFSC on different vegetative, physiological, and/or reproductive parameters. We further reveal that the transcriptomic response of soybean and Arabidopsis to MFSC shares common features associated with reactive oxygen and iron/copper signaling/metabolism. Our study provides unique phenotypic and transcriptomic datasets for dissecting the mechanistic effects of MFSC on the vegetative, physiological, and reproductive processes of a crop plant.

plant biology↗

bioRxiv2023

Employing Deep Learning Model to Evaluate Speech Information in Vocoder Simulations of Auditory Implants

Vocoder simulations have played a crucial role in the development of sound coding and speech processing techniques for auditory implant devices. Vocoders have been extensively used to model the effects of implant signal processing as well as individual anatomy and physiology on speech perception of implant users. Traditionally, such simulations have been conducted on human subjects, which can be time-consuming and costly. In addition, perception of vocoded speech varies significantly across individual subjects, and can be significantly affected by small amounts of familiarization or exposure to vocoded sounds. In this study, we propose a novel method that differs from traditional vocoder studies. Rather than using actual human participants, we use a speech recognition model to examine the influence of vocoder-simulated cochlear implant processing on speech perception. We used the OpenAI Whisper, a recently developed advanced open-source deep learning speech recognition model. The Whisper models performance was evaluated on vocoded words and sentences in both quiet and noisy conditions with respect to several vocoder parameters such as number of spectral bands, input frequency range, envelope cut-off frequency, envelope dynamic range, and number of discriminable envelope steps. Our results indicate that the Whisper model exhibited human-like robustness to vocoder simulations, with performance closely mirroring that of human subjects in response to modifications in vocoder parameters. Furthermore, this proposed method has the advantage of being far less expensive and quicker than traditional human studies, while also being free from inter-individual variability in learning abilities, cognitive factors, and attentional states. Our study demonstrates the potential of employing advanced deep learning models of speech recognition in auditory prosthesis research.

bioengineering↗

bioRxiv2023

Hippocampal mechanisms support cortisol-induced memory enhancements

Stress can powerfully influence episodic memory, often enhancing memory encoding for emotionally salient information. These stress-induced memory enhancements stand at odds with demonstrations that stress and the stress-related hormone cortisol can negatively affect the hippocampus, a brain region important for episodic memory encoding. To resolve this apparent conflict and determine whether and how the hippocampus supports memory encoding under cortisol, we combined behavioral assays of associative memory, high-resolution functional magnetic resonance imaging (fMRI), and pharmacological manipulation of cortisol in a within-participant, double-blinded procedure. Hydrocortisone led to enhanced functional connectivity between hippocampal subregions, which predicted subsequent memory enhancements for emotional information. Cortisol also modified the relationship between hippocampal representations and memory: whereas hippocampal signatures of distinctiveness predicted memory under placebo, relative integration predicted memory under cortisol. Together, these data provide novel evidence that the human hippocampus contains the necessary machinery to support emotional memory enhancements under stress.

neuroscience↗

bioRxiv2023

Reconstructing cellular differentiation networks and identifying cell fate-determining features with CIBER

Trajectory inference methods are frequently used for cell fate analysis, however, most of them are similarity-based and lack an understanding of the causality underlying differentiation processes. Here, we present CIBER, a Causal Inference-Based framework for the Evaluation of feature effects and the Reconstruction of cellular differentiation networks. CIBER provides a novel paradigm for dissecting cell state transitions other than trajectory inference and differential analysis. It is a versatile framework that can be applied to various types of data, including transcriptomic, epigenomic and microarray data. It can identify both known and potential cell-lineage structures with minimal prior knowledge. By integrating the CIBER-learned network with structural causal model and applying in silico perturbation as inventions, we generated an effect matrix that quantifies the impact of different features on each differentiation branch. Using this effect matrix, CIBER can identify crucial features involved in haematopoiesis, even if these features show no significant difference in expression between lineages. Moreover, CIBER can predict novel regulation associations and provide insight into the potential mechanism underlying the influence of transcription factors on biological processes. To validate CIBERs capabilities, we conducted in vivo experiments on Bcl11b, a non-differentially expressed transcription factor identified by CIBER. Our results demonstrate that dysfunction of Bcl11b leads to a bias towards myeloid lineage differentiation at the expense of lymphoid lineage, which is consistent with our predictions.

systems biology↗

bioRxiv2023

The transcriptome of soybean reproductive tissues subjected to water deficit, heat stress, and a combination of water deficit and heat stress.

Global warming and climate change are driving an alarming increase in the frequency and intensity of extreme climate events, such as droughts, heat waves, and their combination, inflicting heavy losses to agricultural production. Recent studies revealed that the transcriptomic responses of different crops to water deficit (WD) or heat stress (HS) is very different from that to a combination of WD+HS. In addition, it was found that the effects of WD, HS, and WD+HS are significantly more devastating when these stresses occur during the reproductive growth phase of crops, compared to vegetative growth. As the molecular responses of different reproductive and vegetative tissues of plants to WD, HS, or WD+HS could be different from each other, and these differences could impact many current and future breeding and/or engineering attempts to enhance the resilience of crops to climate change, we conducted a transcriptomic analysis of different soybean (Glycine max) tissues to WD, HS, and WD+HS. Here we present a reference transcriptomic dataset that includes the response of soybean leaf, pod, anther, stigma, ovary, and sepal to WD, HS, and WD+HS conditions. Mining this data set for the expression pattern of different stress-response transcripts revealed that each tissue had a unique transcriptomic response to each of the different stress conditions. This finding is important as it suggests that attempting to enhance the overall resilience of crops to climate change could require a coordinated approach that simultaneously alters the expression of different groups of transcripts in different tissues in a stress-specific manner. SIGNIFICANCE STATEMENTA reference transcriptomic dataset of different reproductive tissues of soybean subjected to water deficit, heat stress, and their combination, generated by this study, reveals that different tissues display different responses to these stress conditions. Attempting to enhance the resilience of crops to different stress combinations, associated with climate change, might therefore require simultaneously altering the expression of different sets of transcripts in different tissues in a coordinated and stress-specific manner.

plant biology↗

bioRxiv2022

The effects of multifactorial stress combination on rice and maize

The complexity of environmental factors affecting plants is gradually increasing due to global warming, an increase in the number and intensity of climate change-driven weather events, such as droughts, heat waves, and floods, and the accumulation of different pollutants. The impact of multiple stress conditions on plants was recently termed multifactorial stress combination (MFSC) and defined as the occurrence of three or more stressors that impact plants simultaneously or sequentially. We recently reported that with the increased number and complexity of different stressors, the growth and survival of Arabidopsis thaliana seedlings declines; even if the level of each individual stress is low enough to have no significant effect on plants. This finding is alarming since it reveals that MFSCs of different low-level stressors could impact crops and cause a dramatic reduction in overall growth. However, whether MFSC would impact commercial crop cultivars has not been studied. Here, we reveal that a MFSC of 5 different low level abiotic stresses (salinity, heat, the herbicide paraquat, phosphorus deficiency, and the heavy metal cadmium), applied in an increasing level of complexity, has a significant negative impact on the growth and biomass of a commercial rice (Oryza sativa) cultivar and a maize (Zea mays) hybrid. We further report on the first proteomics analysis of MFSC in plants that identified over 300 proteins common to all 4- and 5-MFSCs. Taken together our findings reveal that the impacts of MFSC on two different crop species are severe, and that MFSC may significantly affect agricultural productivity.

plant biology↗

bioRxiv2022

Differential transpiration between pods and leaves during stress combination in soybean

Climate change is causing an increase in the frequency and intensity of droughts, heat waves, and their combinations, diminishing agricultural productivity and destabilizing societies worldwide. We recently reported that during a combination of water deficit (WD) and heat stress (HS) stomata on leaves of soybean plants are closed, while stomata on flowers are open. This unique stomatal response was accompanied by differential transpiration (higher in flowers, while lower in leaves) that cooled flowers during a combination of WD+HS. Here we reveal that developing pods of soybean plants subjected to a combination of WD+HS use a similar acclimation strategy of differential transpiration to reduce internal pod temperature by about 4{degrees}C. We further show that enhanced expression of transcripts involved in abscisic acid degradation accompanies this response, and that preventing pod transpiration by sealing stomata causes a significant increase in internal pod temperature. Using an RNA-Seq analysis of pods developing on plants subjected to WD+HS, we also show that the response of pods to WD, HS, or WD+HS is distinct from that of leaves or flowers. Interestingly, we report that although flower, pod and seed numbers per plant are decreased under conditions of WD+HS, seed mass of plants subjected to WD+HS is larger than that of plants subjected to HS, and number of seeds with suppressed/aborted development is lower in WD+HS compared to HS. Taken together our findings reveal that differential transpiration occurs in pods of soybean plants subjected to WD+HS and that this process limits heat-induced damage to seed production. One sentence summaryDifferential transpiration between pods and leaves of soybean plants subjected to a combination of water deficit and heat stress buffers internal pod temperature.

plant biology↗

bioRxiv2022

An essential host dietary fatty acid promotes TcpH inhibition of TcpP proteolysis enabling virulence gene expression in Vibrio cholerae

Vibrio cholerae is a Gram-negative gastrointestinal pathogen responsible for the diarrheal disease cholera. Expression of key virulence factors, cholera toxin and toxin-coregulated pilus, is regulated indirectly by two single-pass membrane-localized transcription regulators (MLTR), ToxR and TcpP, that promote expression of the transcription activator toxT. TcpP abundance and activity are controlled by TcpH, a single-pass transmembrane protein, which protects TcpP from a two-step proteolytic process known as regulated intramembrane proteolysis (RIP). The mechanism of TcpH mediated protection of TcpP represents a major gap in our understanding of V. cholerae pathogenesis. Absence of tcpH leads to unimpeded degradation of TcpP in vitro and a colonization defect in a neonate mouse model of V. cholerae colonization. Here, we show that TcpH protects TcpP from RIP via direct interaction. We also demonstrate that a dietary fatty acid, -linolenic acid, promotes TcpH-dependent inhibition of RIP via co-association of TcpP and TcpH molecules within detergent-resistant membranes (DRMs; also known as lipid rafts) in a mechanism requiring the TcpH transmembrane domain. Taken together our data support a model where V. cholerae cells use exogenous -linolenic acid to remodel the phospholipid bilayer in vivo, leading to co-association of TcpP and TcpH within DRMs where RIP of TcpP is inhibited by TcpH, thereby promoting V. cholerae pathogenicity. Significance StatementV. cholerae continues to pose a significant global burden on health infection millions of people every year resulting in [~]100,000 deaths annually. The importance of toxT gene expression in V. cholerae pathogenesis has been well established. Our results show that TcpP, one of the major regulators of toxT gene expression, is protected from proteolysis by TcpH, via direct interaction, in the presence of -linolenic acid, an essential dietary fatty acid. Here we identify a physiological relevant host factor that stimulates V. cholerae pathogenicity via TcpH-dependent antagonism of TcpP proteolysis.

microbiology↗