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2,011 result(s) for "Department of Biology "
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Export of Salicylic Acid from the Chloroplast Requires the Multidrug and Toxin Extrusion-Like Transporter EDS5
Salicylic acid (SA) is central for the defense of plants to pathogens and abiotic stress. SA is synthesized in chloroplasts from chorismic acid by an isochorismate synthase (ICS1); SA biosynthesis is negatively regulated by autoinhibitory feedback at ICS1. Genetic studies indicated that the multidrug and toxin extrusion transporter ENHANCED DISEASE SUSCEPTIBILITY5 (EDS5) of Arabidopsis (Arabidopsis thaliana) is necessary for SA accumulation after biotic and abiotic stress, but so far it is not understood how EDS5 controls the biosynthesis of SA. Here, we show that EDS5 colocalizes with a marker of the chloroplast envelope and that EDS5 functions as a multidrug and toxin extrusion-like transporter in the export of SA from the chloroplast to the cytoplasm in Arabidopsis, where it controls the innate immune response. The location at the chloroplast envelope supports a model of the effect of EDS5 on SA biosynthesis: in the eds5 mutant, stress-induced SA is trapped in the chloroplast and inhibits its own accumulation by autoinhibitory feedback.
Prevalence of Intestinal Parasite Infections and Their Associated Factors among Food Handlers Working in Selected Catering Establishments from Bule Hora, Ethiopia
Intestinal parasites are responsible for one of the major health problems like food contamination with socioeconomic effects in the world with a prevalence rate of 30-60%, in developing countries that lie within tropical and subtropical areas. They pose a reasonable public health burden, particularly in low- and middle-income countries, including Ethiopia. Globally, due to intestinal parasitic infections, around 3.5 billion people are affected and more than 200,000 deaths are reported annually. Around 50000 deaths yearly are caused by intestinal parasites in Ethiopia. As such, intestinal parasites perceived global and local burdens to various countries. The risk of food contamination depends largely on the health status of the food handlers, their hygiene, knowledge, and practice of food hygiene. Food handlers with poor personal hygiene and sanitation conditions are the major potential sources of intestinal helminthes and protozoa worldwide. The proposed study was aimed at evaluating prevalence of intestinal parasitic infections and their associated factors among food handlers working in selected catering establishments. A cross-sectional study was conducted in Bule Hora Town from March to April 2020. A total of 136 catering establishments were selected using a systematic sampling technique. Data analysis was done using SPSS version 20. The prevalence of intestinal parasites in this study was 46.3%. Entamoeba histolytica was the most predominant parasite (33.3%, i.e., 21/63) while Giardia lamblia was the least (11.1%, i.e., 7/63). Consumption of vended or borehole water and hygienic practices such as hand washing before eating, after using toilet, before cooking and trimming of finger nail and wearing proper working clothes and shoes were statistically significant with intestinal parasitic infection (P<0.05). Generally, the prevalence of intestinal parasitic infection in this study was high and contributed by low socioeconomic status and poor environmental and personal hygiene. Measures including education on personal hygiene, environmental sanitation, drinking water supply, regular medical checkups, and treatment should be taken into account to reduce the prevalence of intestinal parasites.
Activation-Induced T Helper Cell Death Contributes to Th1/Th2 Polarization following Murine Schistosoma japonicum Infection
In chronic infectious diseases, such as schistosomiasis, pathogen growth and immunopathology are affected by the induction of a proper balanced Th1/Th2 response to the pathogen and by antigen-triggered activation-induced T cell death. Here, by using S. japonicum infection or schistosome antigens-immunized mouse model, or antigens in vitro stimulation, we report that during the early stage of S. japonicum infection, nonegg antigens trigger Th2 cell apoptosis via the granzyme B signal pathway, contributing to Th1 polarization, which is thought to be associated with worm clearance and severe schistosomiasis. Meanwhile, after the adult worms lay their eggs, the egg antigens trigger Th1 cell apoptosis via the caspase pathway, contributing to Th2 polarization, which is associated with mild pathology and enhanced survival of both worms and their hosts. Thus, our study suggests that S. japonicum antigen-induced Th1 and Th2 cell apoptosis involves the Th1/Th2 shift and favorites both hosts and parasites.
A reference gene catalogue of the pig gut microbiome
The pig is a major species for livestock production and is also extensively used as the preferred model species for analyses of a wide range of human physiological functions and diseases(1). The importance of the gut microbiota in complementing the physiology and genome of the host is now well recognized(2). Knowledge of the functional interplay between the gut microbiota and host physiology in humans has been advanced by the human gut reference catalogue(3,4). Thus, establishment of a comprehensive pig gut microbiome gene reference catalogue constitutes a logical continuation of the recently published pig genome(5). By deep metagenome sequencing of faecal DNA from 287 pigs, we identified 7.7 million non-redundant genes representing 719 metagenomic species. Of the functional pathways found in the human catalogue, 96% are present in the pig catalogue, supporting the potential use of pigs for biomedical research. We show that sex, age and host genetics are likely to influence the pig gut microbiome. Analysis of the prevalence of antibiotic resistance genes demonstrated the effect of eliminating antibiotics from animal diets and thereby reducing the risk of spreading antibiotic resistance associated with farming systems.
Compensation irradiance and depth limits of transplanted eelgrass (Zostera marina) along a eutrophication gradient
The global seagrass decline has prompted numerous restoration efforts to reverse current trends. Yet, restoration efforts are challenged by ecological feedbacks and prevalent stressors. Identifying these stressors and the thresholds where seagrass shoot production becomes negative is vital to improve site-selection procedures and increase restoration success. In this study, we investigated the ecological compensation irradiance (ECI) and depth limit of eelgrass ( Zostera marina L) transplants along a eutrophication gradient. This was accomplished by establishing eelgrass transplants along eutrophication and depth gradients while continuously measuring benthic Photosynthetically Active Radiation (PAR). High-temporal monitoring of shoot count allowed precise estimates of shoot production, which was applied to modified photosynthesis-irradiance curves, thereby estimating the ECI. The ECI fell within the interval 2.6 – 9.8 E m -2 d -1 and responded distinctly along the eutrophication gradient, decreasing as eutrophication and nutrient-derived stressors were alleviated. The depth limits were concurrently controlled by irradiance and ECI and similarly responded along the eutrophication gradient, increasing from 1.1 m at the innermost station to 4.7 – 5.6 m at the two outermost least eutrophic stations. The results demonstrate that the ECI of eelgrass varies according to the local environment, with implications for habitat suitability assessment and site selection procedures in restoration efforts.
Regulatory role of NADPH oxidases in symbiosis and dysbiosis in the sea anemone Aiptasia
The endosymbiosis between cnidarians and photosynthetic dinoflagellates of the Symbiodiniaceae family forms the foundation of coral reef ecosystems. Prolonged environmental shifts can disrupt the cnidarian–Symbiodiniaceae partnership, triggering dysbiosis and coral bleaching and ultimately resulting in coral starvation, mortality, and the collapse of reef ecosystems. Despite its significance, critical gaps remain in our understanding of the cellular mechanisms governing symbiosis and dysbiosis. Innate immune genes and pathways are highly conserved across the Metazoa, including in cnidarians. Among these is NADPH oxidase (NOX), a key enzyme responsible for generating reactive oxygen species (ROS), primarily for microbial degradation within phagolysosomes. In this study, we hypothesize that NOX plays a role in the regulation of cnidarian–Symbiodiniaceae symbiosis and the host phagosomal maturation process. We investigated NOX function in relation to symbiotic state and heat stress in the sea anemone Exaiptasia diaphana (commonly called aiptasia), a model for cnidarian–Symbiodiniaceae symbiosis and dysbiosis. Our findings show that NOX gene and protein expression is suppressed in the symbiotic state, supporting the hypothesis that symbionts modulate host innate immunity. However, upon heat treatment, we observed increased NOX expression and activity along with NOX localization around algal symbionts, suggesting that host phagosomal maturation processes are engaged during bleaching. We propose a model where the phagocytic NOX complex becomes activated during symbiosis breakdown and bleaching. Our findings support the hypothesis that in situ degradation, facilitated by ROS generated by NOX, plays a key role in the process of dysbiosis. This work contributes to our understanding of cnidarian innate immunity, highlighting critical steps in dysbiosis and phagosomal maturation processes within cnidarian–Symbiodiniaceae symbiosis.
Impact of oceanographic gradients and marine heatwaves on the picophytoplankton community in the Northern California Current System
The Northern California Current (NCC) system is a productive coastal ecosystem with a mosaic of temporal and spatial features. The phytoplankton community plays a crucial role in supporting the rich ecosystem and economically important fisheries of the NCC. Our study integrates data across two years (2022-2023) and multiple transects to investigate the community composition of two major phytoplankton groups in the NCC: picocyanobacteria and photosynthetic picoeukaryotes (PPE). The abundances and cell sizes of the phytoplankton were measured using flow cytometry. We found PPE present at similar concentrations in both summer and winter, while picocyanobacteria were much more abundant in the summer than the winter. The relationship between the picocyanobacteria and PPE varied across on- to off-shore transects with different coastal bathymetry. Abundances of both picophytoplankton increased with distance from shore. Cell size also varied along these gradients. Sampling during a marine heatwave in summer 2023 revealed a shift towards smaller picophytoplankton. Overall, these data reveal a dynamic microbial community underlying a productive coastal system, which could inform management decisions and future ecosystem models in the context of climate change and marine heat waves.
Female behaviour drives expression and evolution of gustatory receptors in butterflies
Secondary plant compounds are strong deterrents of insect oviposition and feeding, but may also be attractants for specialist herbivores. These insect-plant interactions are mediated by insect gustatory receptors (Grs) and olfactory receptors (Ors). An analysis of the reference genome of the butterfly Heliconius melpomene, which feeds on passion-flower vines (Passiflora spp.), together with whole-genome sequencing within the species and across the Heliconius phylogeny has permitted an unprecedented opportunity to study the patterns of gene duplication and copy-number variation (CNV) among these key sensory genes. We report in silico gene predictions of 73 Gr genes in the H. melpomene reference genome, including putative CO2, sugar, sugar alcohol, fructose, and bitter receptors. The majority of these Grs are the result of gene duplications since Heliconiusshared a common ancestor with the monarch butterfly or the silkmoth. Among Grs but notOrs, CNVs are more common within species in those gene lineages that have also duplicated over this evolutionary time-scale, suggesting ongoing rapid gene family evolution. Deep sequencing (,1 billion reads) of transcriptomes from proboscis and labial palps, antennae, and legs of adult H. melpomene males and females indicates that 67 of the predicted 73 Gr genes and 67 of the 70 predicted Or genes are expressed in these three tissues. Intriguingly, we find that one-third of all Grs show female-biased gene expression (n = 26) and nearly all of these (n = 21) are Heliconius-specific Grs. In fact, a significant excess of Grs that are expressed in female legs but not male legs are the result of recent gene duplication. This difference in Gr gene expression diversity between the sexes is accompanied by a striking sexual dimorphism in the abundance of gustatory sensilla on the forelegs of H. melpomene, suggesting that female oviposition behaviour drives the evolution of new gustatory receptors in butterfly genomes.
Effects of the native-invasive-alien substitution of ecosystem engineers on sediment reworking and nutrient cycling
IntroductionRia de Aveiro, a coastal lagoon on the Atlantic coast of Portugal, was invaded by Arenicola spp. 15 years ago, with the new species successfully spreading throughout the system and replacing the native Diopatra species. With opposite bioturbation traits (Diopatra as sediment stabilizers vs Arenicola as sediment reworkers), the impacts of this replacement can spread across the entire ecosystem.MethodsIn a 21 days microcosm study, we evaluated the effects of the incremental substitution of Diopatra by Arenicola species on relevant proxies of ecosystem functioning, such as sediment reworking depths and nutrient dynamics.ResultsThe results show a strong directional influence on most of the analyzed parameters as a response to higher densities of Arenicola. Specifically, Arenicola-dominated communities were characterized by deeper reworking depths and higher concentrations of ammonium and phosphate in the water column.DiscussionThese results are discussed in the context of the available knowledge on the accompanying biological communities, which are typically fostered by these distinct functional groups. Therefore, there is strong evidence that the introduction of a novel species’ trait will have major consequences across several levels of the invaded system.