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Cell Host & Microbe Nov 2022Gut-microbiota membership is associated with diverse neuropsychological outcomes, including substance use disorders (SUDs). Here, we use mice colonized with Citrobacter...
Gut-microbiota membership is associated with diverse neuropsychological outcomes, including substance use disorders (SUDs). Here, we use mice colonized with Citrobacter rodentium or the human γ-Proteobacteria commensal Escherichia coli HS as a model to examine the mechanistic interactions between gut microbes and host responses to cocaine. We find that cocaine exposure increases intestinal norepinephrine levels that are sensed through the bacterial adrenergic receptor QseC to promote intestinal colonization of γ-Proteobacteria. Colonized mice show enhanced host cocaine-induced behaviors. The neuroactive metabolite glycine, a bacterial nitrogen source, is depleted in the gut and cerebrospinal fluid of colonized mice. Systemic glycine repletion reversed, and γ-Proteobacteria mutated for glycine uptake did not alter the host response to cocaine. γ-Proteobacteria modulated glycine levels are linked to cocaine-induced transcriptional plasticity in the nucleus accumbens through glutamatergic transmission. The mechanism outline here could potentially be exploited to modulate reward-related brain circuits that contribute to SUDs.
Topics: Mice; Humans; Animals; Cocaine; Proteobacteria; Citrobacter rodentium; Gastrointestinal Microbiome; Bacteria; Escherichia coli; Glycine
PubMed: 36323315
DOI: 10.1016/j.chom.2022.09.014 -
Microbiome Dec 2022Mounting experimental evidence has shown that the gut microbiota plays a significant role in the pathogenesis of mastitis, and clinical investigations have found that...
BACKGROUND
Mounting experimental evidence has shown that the gut microbiota plays a significant role in the pathogenesis of mastitis, and clinical investigations have found that the occurrence of mastitis is correlated with ruminal dysbiosis. However, the underlying mechanism by which the ruminal microbiota participates in the development of mastitis remains unknown.
RESULTS
In the present study, we found that cows with clinical mastitis had marked systemic inflammation, which was associated with significant ruminal dysbiosis, especially enriched Proteobacteria in the rumen. Ruminal microbiota transplantation from mastitis cows (M-RMT) to mice induced mastitis symptoms in recipient mice along with increased mammary proinflammatory signature activation of the TLR4-cGAS-STING-NF-κB/NLRP3 pathways. M-RMT also induced mucosal inflammation and impaired intestinal barrier integrity, leading to increased endotoxemia and systemic inflammation. Moreover, we showed that M-RMT mirrored ruminal microbiota disruption in the gut of recipient mice, as evidenced by enriched Proteobacteria and similar bacterial functions, which were correlated with most proinflammatory parameters and serum lipopolysaccharide (LPS) levels in mice. Recurrent low-grade LPS treatment mirrored gut dysbiosis-induced endotoxemia and caused severe mastitis in mice. Furthermore, we found that gut dysbiosis-derived LPS reduced host alkaline phosphatase activity by activating neuraminidase (Neu), which facilitates low-grade LPS exposure and E. coli-induced mastitis in mice. Conversely, treatment with calf intestinal alkaline phosphatase or the Neu inhibitor zanamivir alleviated low-grade LPS exposure and E. coli-induced mastitis in mice.
CONCLUSIONS
Our results suggest that ruminal dysbiosis-derived low-grade endotoxemia can cause mastitis and aggravate pathogen-induced mastitis by impairing host anti-inflammatory enzymes, which implies that regulating the ruminal or gut microbiota to prevent low-grade systemic inflammation is a potential strategy for mastitis intervention. Video Abstract.
Topics: Female; Humans; Animals; Cattle; Mice; Dysbiosis; Endotoxemia; Lipopolysaccharides; Alkaline Phosphatase; Escherichia coli; Mastitis; Anti-Inflammatory Agents; Inflammation; Proteobacteria
PubMed: 36451232
DOI: 10.1186/s40168-022-01402-z -
Current Biology : CB Mar 2023Muñoz-Gómez and Hess introduce purple photosymbioses, which involve a heterotrophic protist host and anoxygenic photosymbionts from the phylum Proteobacteria.
Muñoz-Gómez and Hess introduce purple photosymbioses, which involve a heterotrophic protist host and anoxygenic photosymbionts from the phylum Proteobacteria.
Topics: Proteobacteria; Symbiosis; Photosynthesis
PubMed: 36917934
DOI: 10.1016/j.cub.2023.01.015 -
Microbial Physiology 2021Predatory bacteria gained interest in the last 20 years. Nevertheless, only a few species are well characterized. The endobiotic predator Bdellovibrio bacteriovorus... (Review)
Review
Predatory bacteria gained interest in the last 20 years. Nevertheless, only a few species are well characterized. The endobiotic predator Bdellovibrio bacteriovorus invades its prey to consume it from the inside, whereas Myxococcus xanthus hunts as a whole group to overcome its prey. Both species were described to prey on cyanobacteria as well. This minireview summarizes the findings of the last 20 years of predatory bacteria of cyanobacteria and is supplemented by new findings from a screening experiment for bacterial predators of the model organism Anabaena variabilis PCC 7937. Known predatory bacteria of cyanobacteria belong to the phyla Proteobacteria, Bacteroidetes, and Firmicutes and follow different hunting strategies. The underlying mechanisms are in most cases not known in much detail. Isolates from the screening experiment were clustered after predation behaviour and analyzed with respect to their size. The effect of predation in high nitrate levels and the occurrence of nitrogen-fixing cells, called heterocysts, are addressed.
Topics: Animals; Bdellovibrio bacteriovorus; Cyanobacteria; Myxococcus xanthus; Predatory Behavior
PubMed: 34010833
DOI: 10.1159/000516427 -
Frontiers in Cellular and Infection... 2023Rickettial agents are a diverse group of alpha-proteobacteria within the order Rickettsiales, which possesses two families with human pathogens, Rickettsiaceae and... (Review)
Review
Rickettial agents are a diverse group of alpha-proteobacteria within the order Rickettsiales, which possesses two families with human pathogens, Rickettsiaceae and Anaplasmataceae. These obligate intracellular bacteria are most frequently transmitted by arthropod vectors, a first step in the pathogens' avoidance of host cell defenses. Considerable study of the immune responses to infection and those that result in protective immunity have been conducted. Less study has focused on the initial events and mechanism by which these bacteria avoid the innate immune responses of the hosts to survive within and propagate from host cells. By evaluating the major mechanisms of evading innate immunity, a range of similarities among these bacteria become apparent, including mechanisms to escape initial destruction in phagolysosomes of professional phagocytes, those that dampen the responses of innate immune cells or subvert signaling and recognition pathways related to apoptosis, autophagy, proinflammatory responses, and mechanisms by which these microbes attach to and enter cells or those molecules that trigger the host responses. To illustrate these principles, this review will focus on two common rickettsial agents that occur globally, species and .
Topics: Humans; Rickettsia Infections; Immunity, Innate; Rickettsia; Anaplasma phagocytophilum; Autophagy
PubMed: 37228668
DOI: 10.3389/fcimb.2023.1187267 -
Environmental Microbiology Reports Apr 2020Arsenic is a toxin, ranking first on the Agency for Toxic Substances and Disease Registry and the Environmental Protection Agency Priority List of Hazardous Substances.... (Review)
Review
Arsenic is a toxin, ranking first on the Agency for Toxic Substances and Disease Registry and the Environmental Protection Agency Priority List of Hazardous Substances. Chronic exposure increases the risk of a broad range of human illnesses, most notably cancer; however, there is significant variability in arsenic-induced disease among exposed individuals. Human genetics is a known component, but it alone cannot account for the large inter-individual variability in the presentation of arsenicosis symptoms. Each part of the gastrointestinal tract (GIT) may be considered as a unique environment with characteristic pH, oxygen concentration, and microbiome. Given the well-established arsenic redox transformation activities of microorganisms, it is reasonable to imagine how the GIT microbiome composition variability among individuals could play a significant role in determining the fate, mobility and toxicity of arsenic, whether inhaled or ingested. This is a relatively new field of research that would benefit from early dialogue aimed at summarizing what is known and identifying reasonable research targets and concepts. Herein, we strive to initiate this dialogue by reviewing known aspects of microbe-arsenic interactions and placing it in the context of potential for influencing host exposure and health risks. We finish by considering future experimental approaches that might be of value.
Topics: Arsenates; Arsenic; Arsenite Transporting ATPases; Bacteria; Bacteroidetes; Bioaccumulation; Drug Resistance; Escherichia coli Proteins; Firmicutes; Gastrointestinal Microbiome; Gastrointestinal Tract; Genes, Bacterial; Humans; Ion Pumps; Metagenomics; Molecular Chaperones; Multienzyme Complexes; Proteobacteria; RNA, Ribosomal, 16S
PubMed: 31773890
DOI: 10.1111/1758-2229.12814 -
Genome Biology and Evolution Jun 2023The determination of the last common ancestor (LCA) of a group of species plays a vital role in evolutionary theory. Traditionally, an LCA is inferred by the rooting of...
The determination of the last common ancestor (LCA) of a group of species plays a vital role in evolutionary theory. Traditionally, an LCA is inferred by the rooting of a fully resolved species tree. From a theoretical perspective, however, inference of the LCA amounts to the reconstruction of just one branch-the root branch-of the true species tree and should therefore be a much easier task than the full resolution of the species tree. Discarding the reliance on a hypothesized species tree and its rooting leads us to reevaluate what phylogenetic signal is directly relevant to LCA inference and to recast the task as that of sampling the total evidence from all gene families at the genomic scope. Here, we reformulate LCA and root inference in the framework of statistical hypothesis testing and outline an analytical procedure to formally test competing a priori LCA hypotheses and to infer confidence sets for the earliest speciation events in the history of a group of species. Applying our methods to two demonstrative data sets, we show that our inference of the opisthokonta LCA is well in agreement with the common knowledge. Inference of the proteobacteria LCA shows that it is most closely related to modern Epsilonproteobacteria, raising the possibility that it may have been characterized by a chemolithoautotrophic and anaerobic life style. Our inference is based on data comprising between 43% (opisthokonta) and 86% (proteobacteria) of all gene families. Approaching LCA inference within a statistical framework renders the phylogenomic inference powerful and robust.
Topics: Phylogeny; Biological Evolution; Genomics; Genome; Eukaryota; Proteobacteria
PubMed: 37247390
DOI: 10.1093/gbe/evad096 -
Scientific Reports Mar 2022Rickettsia species are endosymbionts hosted by arthropods and are known to cause mild to fatal diseases in humans. Here, we analyse the evolution and diversity of 34... (Meta-Analysis)
Meta-Analysis
Rickettsia species are endosymbionts hosted by arthropods and are known to cause mild to fatal diseases in humans. Here, we analyse the evolution and diversity of 34 Rickettsia species using a pangenomic meta-analysis (80 genomes/41 plasmids). Phylogenomic trees showed that Rickettsia spp. diverged into two Spotted Fever groups, a Typhus group, a Canadensis group and a Bellii group, and may have inherited their plasmids from an ancestral plasmid that persisted in some strains or may have been lost by others. The results suggested that the ancestors of Rickettsia spp. might have infected Acari and/or Insecta and probably diverged by persisting inside and/or switching hosts. Pangenomic analysis revealed that the Rickettsia genus evolved through a strong interplay between genome degradation/reduction and/or expansion leading to possible distinct adaptive trajectories. The genus mainly shared evolutionary relationships with α-proteobacteria, and also with γ/β/δ-proteobacteria, cytophagia, actinobacteria, cyanobacteria, chlamydiia and viruses, suggesting lateral exchanges of several critical genes. These evolutionary processes have probably been orchestrated by an abundance of mobile genetic elements, especially in the Spotted Fever and Bellii groups. In this study, we provided a global evolutionary genomic view of the intracellular Rickettsia that may help our understanding of their diversity, adaptation and fitness.
Topics: Animals; Arthropods; Evolution, Molecular; Gammaproteobacteria; Genomics; Phylogeny; Rickettsia; Spotted Fever Group Rickettsiosis
PubMed: 35264613
DOI: 10.1038/s41598-022-07725-z -
G3 (Bethesda, Md.) Jan 2021Homologous recombination is a key pathway found in nearly all bacterial taxa. The recombination complex not only allows bacteria to repair DNA double-strand breaks but...
Homologous recombination is a key pathway found in nearly all bacterial taxa. The recombination complex not only allows bacteria to repair DNA double-strand breaks but also promotes adaption through the exchange of DNA between cells. In Proteobacteria, this process is mediated by the RecBCD complex, which relies on the recognition of a DNA motif named Chi to initiate recombination. The Chi motif has been characterized in Escherichia coli and analogous sequences have been found in several other species from diverse families, suggesting that this mode of action is widespread across bacteria. However, the sequences of Chi-like motifs are known for only five bacterial species: E. coli, Haemophilus influenzae, Bacillus subtilis, Lactococcus lactis, and Staphylococcus aureus. In this study, we detected putative Chi motifs in a large dataset of Proteobacteria and identified four additional motifs sharing high sequence similarity and similar properties to the Chi motif of E. coli in 85 species of Proteobacteria. Most Chi motifs were detected in Enterobacteriaceae and this motif appears well conserved in this family. However, we did not detect Chi motifs for the majority of Proteobacteria, suggesting that different motifs are used in these species. Altogether these results substantially expand our knowledge on the evolution of Chi motifs and on the recombination process in bacteria.
Topics: DNA, Bacterial; Escherichia coli; Exodeoxyribonuclease V; Exodeoxyribonucleases; Proteobacteria; Recombination, Genetic
PubMed: 33561247
DOI: 10.1093/g3journal/jkaa054 -
The Veterinary Clinics of North... Nov 2022Emerging evidence regarding the microbiome of liver abscesses (LAs) and the gastrointestinal tract of cattle suggests that a reexamination of the etiopathogenesis of LAs... (Review)
Review
Emerging evidence regarding the microbiome of liver abscesses (LAs) and the gastrointestinal tract of cattle suggests that a reexamination of the etiopathogenesis of LAs is warranted. Microbiome studies using 16S rRNA gene sequencing have demonstrated that LAs are highly polymicrobial, and hundreds of bacterial taxa are typically found in these lesions at slaughter. Fusobacteria and Bacteroidetes are equally dominant phyla within LAs, followed by Proteobacteria. The gut-liver axis (ie, bidirectional crosstalk between the gut and liver) is linked with a variety of liver diseases in humans, and investigation of host-microbiome interactions in cattle may lead to improved methods of prevention.
Topics: Animals; Bacteroidetes; Cattle; Cattle Diseases; Humans; Liver Abscess; Microbiota; Proteobacteria; RNA, Ribosomal, 16S
PubMed: 36243459
DOI: 10.1016/j.cvfa.2022.08.004