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It is often difficult to identify the molecular mechanisms that underlie interactions between species. Using Caenorhabditis elegans as a model system,Patange et al. recently demonstrated that H 2 S mediates interactions between C. elegans and Actinobacteria., Competing Interests: Declaration of interests No interests are declared., (Copyright © 2025 Elsevier Ltd. All rights reserved.)

Transmission of immune responses from one generation to the next represents a powerful adaptive mechanism to protect an organism's descendants. Parental infection by the natural C. elegans pathogen Pseudomonas vranovensis induces a protective response in progeny, but the bacterial cues and intergenerational signal driving this response were previously unknown. Here, we find that animals activate a protective stress response program upon exposure to P. vranovensis-derived cyanide and that a metabolic byproduct of cyanide detoxification, β-cyanoalanine, acts as an intergenerational signal to protect progeny from infection. Remarkably, this mechanism does not require direct parental infection; rather, exposure to pathogen-derived volatiles is sufficient to enhance the survival of the next generation, indicating that parental surveillance of environmental cues can activate a protective intergenerational response. Therefore, the mere perception of a pathogen-derived toxin, in this case cyanide, can protect an animal's progeny from future pathogenic challenges., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2025 Elsevier Inc. All rights reserved.)

Canonical polyamines such as agmatine, putrescine, and spermidine are evolutionarily conserved metabolites found in nearly all forms of life ranging from bacteria to humans. Recently, interactions between polyamines produced by gut bacteria and human intestinal cells have been proposed to contribute to both Irritable Bowel Syndrome with Diarrhea (IBS-D) and inflammatory bowel diseases. However, the molecular mechanisms that underlie these effects are often unclear due in part to limitations in the methods used to manipulate and study polyamine functions in vivo. Here, we developed a Caenorhabditis elegans based screening platform and a modified LC-MS approach for profiling polyamine metabolites. We combined these methods to make the unexpected discovery that dysfunctional polyamine metabolism in both Gram-negative ( E. coli ) and Gram-positive ( B. subtilis ) bacteria can result in the accumulation of a noncanonical polyamine intermediate, N 1 -Aminopropylagmatine (N 1 -APA). We further find that N 1 -APA is produced via spermidine synthase (SpeE) and that it is bioactive when encountered by animals. Specifically, we find that when N 1 -APA is produced by bacteria in animal intestines it can be transported into intestinal cells via the polyamine transporter CATP-5 where it antagonizes both animal development and mitochondrial function across diverse animal species. Lastly, we find that N 1 -APA functions analogously to the deoxyhypusine synthase inhibitor GC7. For example, like GC7, N 1 -APA antagonizes eIF5A hypusination and inhibits the alternative activation of mammalian macrophages. To our knowledge, these findings are the first to demonstrate that N 1 -APA is a bioactive metabolite and that bacteria can produce a small molecule that functions similarly to existing deoxyhypusine synthase inhibitors. Furthermore, these results suggest an exciting new mechanistic hypothesis for why the loss of speB in gut microbes, including E. coli, has been both linked to inflammatory bowel disease (IBD) in humans and found to drive IBD in germ free mice., Competing Interests: Declarations of Interest The authors declare that they have no competing interests.

Penicillin-binding proteins (PBPs) are an essential family of bacterial enzymes that are covalently inhibited by the β-lactam class of antibiotics. PBP inhibition disrupts peptidoglycan biosynthesis, which results in deficient growth and proliferation, and ultimately leads to lysis. IC 50 values are often employed as descriptors of enzyme inhibition and inhibitor selectivity, but can be misleading in the study of time-dependent, covalent inhibitors. Due to this disconnect, the second-order rate constant, k inact / K I , is a more appropriate metric of covalent-inhibitor potency. Despite being the gold standard measurement of potency, k inact / K I values are typically obtained from in vitro assays, which limits assay throughput if investigating an enzyme family with multiple homologues (such as the PBPs). Therefore, we developed a whole-cell k inact / K I assay to define inhibitor potency for the PBPs in Streptococcus pneumoniae using the fluorescent, activity-based probe, Bocillin-FL. Our results align with in vitro k inact / K I data and show a comparable relationship to previously established IC 50 values. These results support the validity of our in vivo k inact / K I method as a means of obtaining β-lactam potency for a suite of PBPs to enable structure-activity relationship studies.

Three new species of Jainus Mizelle, Kritzky & Crane, 1968, are described parasitizing the gill filaments of Triportheus angulatus (Spix & Agassiz) (Characiformes: Triportheidae), an omnivorous fish endemic to the Amazon River basin. Jainus iquitensis n. sp. is characterized by the morphology of the vagina, which is bell-shaped, with a canal as a sclerotized tube and the morphology of hook pair VII, which in the new species presents an inflated base, a characteristic not observed in other congeners. Jainus loretoensis n. sp. is unique among Jainus species due to the morphology of its Y-shaped ventral anchors, with an arrow-shaped superficial root and a finger-shaped deep root. Jainus sardinae n. sp. is characterized by presenting a slender, small J-shaped tube with a sigmoid accessory piece and a ventral anchor that is Y-shaped, with inconspicuous finger-shaped deep root and superficial root with rounded ending with a chin-shaped projection. These findings add three new species to the previously reported two Jainus species from Peru., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Penicillin-binding proteins (PBPs) are an essential family of bacterial enzymes that are inhibited by the β-lactam class of antibiotics. PBP inhibition disrupts cell wall biosynthesis, which results in deficient growth and proliferation, and ultimately leads to lysis. IC 50 values are often employed as descriptors of enzyme inhibition and inhibitor selectivity but can be misleading in the study of time-dependent, irreversible inhibitors. Due to this disconnect, the second order rate constant k inact / K I is a more appropriate metric of covalent inhibitor potency. Despite being the gold standard measurement of potency, k inact / K I values are typically obtained from in vitro assays, which limits assay throughput if investigating an enzyme family with multiple homologs (such as the PBPs). Therefore, we developed a whole-cell k inact / K I assay to define inhibitor potency for the PBPs in Streptococcus pneumoniae using the fluorescent activity-based probe Bocillin-FL. Our results align with in vitro k inact / K I data and show a comparable relationship to previously established IC 50 values. These results support the validity of our in vivo k inact / K I method as a means of obtaining a full picture of β-lactam potency for a suite of PBPs.

Pygocentrus nattereri Kner, 1858 and Serrasalmus rhombeus (Linnaeus, 1766) are species of serrasalmids sold in open-air markets and market municipalities in Maranhão, Brazil. Fifty-two individuals of P. nattereri and 52 of S. rhombeus were acquired from a fish market in the Municipality of Pinheiro,Maranhão, Brazil, and transported to the laboratory of "Inmunohistoquímica" from "Universidade Estadual do Maranhão" (UEMA). The lateral musculature of the fish was analyzed by making fine cuts, internal organs were placed in Petri dishes with distilled water, and with the aid of tweezers and needles, the tissue was examined by making fine cuts that allowed observation inside them. The results of the study revealed the presence of nematode larvae L3 of Contracaecum sp. was found parasitizing the visceral cavity, intestines, pyloric cecum, and stomach of P. nattereri and S. rhombeus. This study alerts local authorities and the population to take the necessary measures to prevent the accidental ingestion of endoparasites with zoonotic potential.

Purpose: The present study aims to report the occurrence of Eustrongylides sp. in some neotropical fish species commercialized in the Peruvian Amazonia., Methods: Samples of young farmed Arapaima gigas were collected from a fish farmer; young Brachyplatystoma tigrinum were acquired from a fish exporter and samples of adult specimens of Acestrorhynchus falcirostris, Pseudoplatystoma punctifer, Cichla monoculus, Hoplias malabaricus, Hydrolycus scomberoides, Raphiodon vulpinus, and Serrasalmus rhombeus were acquired from a fish market of Iquitos, Loreto-Peru. Samples were transported to the "Laboratorio de Parasiología y Sanidad Acuícola" from "Instituto de Investigaciones de la Amazonía Peruana" located in Iquitos, Peru., Results: Larvae L4 of Eustrongylides sp. were found in the host body, in the muscle, and in the visceral cavity of studied fish species. Notorious damages were reported in young A. gigas (lumps in the muscle, inflammation and severe redness of the skin) and in young B. tigrinum (perforation of the abdominal cavity), while in adult specimens of the remaining species, no external damage was reported., Conclusion: The presence of Eustrongylides sp. in various fish species collected in the city of Iquitos-Peru contributes to the distribution of this parasite in the Peruvian Amazon, reporting it, for the first time in this country. Its presence in the muscle of various fish species commercialized in fish markets, warm a possible public health concern and implications for their marketability in the city of Iquitos, Peru., (© 2022. The Author(s) under exclusive licence to Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

Penicillin-binding proteins (PBPs) make up an essential class of bacterial enzymes that carry out the final steps of peptidoglycan synthesis and regulate the recycling of this polymeric structure. PBPs are an excellent drug target and have been the most clinically relevant antibacterial target since the 1940s with the introduction of β-lactams. Despite this, a large gap in knowledge remains regarding the individual function and regulation of each PBP homologue in most bacteria. This can be attributed to a lack of chemical tools and methods that enable the study of individual PBPs in an activity-dependent manner and in their native environment. The development of such methods in Gram-negative bacteria has been particularly challenging due to the presence of an outer membrane and numerous resistance mechanisms. To address this, we have developed an optimized live-cell assay for screening inhibitors of the PBPs in Escherichia coli MG1655. We utilized EDTA to permeabilize Gram-negative cells, enabling increased penetration of our readout probe, Bocillin-FL, and subsequent analysis of PBP-inhibition profiles. To identify scaffolds for future development of PBP-selective activity-based probes, we screened ten β-lactams, one diazabicyclooctane, and one monobactam for their PBP-selectivity profiles in E. coli MG1655. These results demonstrate the utility of our assay for the screening of inhibitors in live, non-hypersusceptible Gram-negative organisms.

Bacillus thuringiensis and other members of the Bacillus cereus family are resistant to many β-lactams. Resistance is dependent upon the extracytoplasmic function sigma factor σ P . We used label-free quantitative proteomics to identify proteins whose expression was dependent upon σ P . We compared the protein profiles of strains which either lacked σ P or overexpressed σ P . We identified 8 members of the σ P regulon which included four β-lactamases as well as three penicillin-binding proteins (PBPs). Using transcriptional reporters, we confirmed that these genes are induced by β-lactams in a σ P -dependent manner. These genes were deleted individually or in various combinations to determine their role in resistance to a subset of β-lactams, including ampicillin, methicillin, cephalexin, and cephalothin. We found that different combinations of β-lactamases and PBPs are involved in resistance to different β-lactams. Our data show that B. thuringiensis utilizes a suite of enzymes to protect itself from β-lactam antibiotics. IMPORTANCE Antimicrobial resistance is major concern for public health. β-Lactams remain an important treatment option for many diseases. However, the spread of β-lactam resistance continues to rise. Many pathogens acquire antibiotic resistance from environmental bacteria. Thus, understanding β-lactam resistance in environmental strains may provide insights into additional mechanisms of antibiotic resistance. Here, we describe how a single regulatory system, σ P , in B. thuringiensis controls expression of multiple genes involved in resistance to β-lactams. Our findings indicate that some of these genes are partially redundant. Our data also suggest that the large number of genes controlled by σ P results in increased resistance to a wider range of β-lactam classes than any single gene could provide.

β-Lactams are a class of antibiotics that target the synthesis of peptidoglycan, an essential component of the cell wall. β-Lactams inhibit the function of penicillin-binding proteins (PBPs), which form the cross-links between strands of peptidoglycan. Resistance to β-lactams complicates the treatment of bacterial infections. In recent years, the spread of β-lactam resistance has increased with growing intensity. Resistance is often conferred by β-lactamases, which inactivate β-lactams, or the expression of alternative β-lactam-resistant PBPs. σ P is an extracytoplasmic function (ECF) σ factor that controls β-lactam resistance in the species Bacillus thuringiensis , Bacillus cereus , and Bacillus anthracis σ P is normally held inactive by the anti-σ factor RsiP. σ P is activated by β-lactams that trigger the proteolytic destruction of RsiP. Here, we identify the penicillin-binding protein PbpP and demonstrate its essential role in the activation of σ P Our data show that PbpP is required for σ P activation and RsiP degradation. Our data suggest that PbpP acts as a β-lactam sensor since the binding of a subset of β-lactams to PbpP is required for σ P activation. We find that PbpP likely directly or indirectly controls site 1 cleavage of RsiP, which results in the degradation of RsiP and, thus, σ P activation. σ P activation results in increased expression of β-lactamases and, thus, increased β-lactam resistance. This work is the first report of a PBP acting as a sensor for β-lactams and controlling the activation of an ECF σ factor. IMPORTANCE The bacterial cell envelope is the target for numerous antibiotics. Many antibiotics target the synthesis of peptidoglycan, which is a central metabolic pathway essential for bacterial survival. One of the most important classes of antibiotics has been β-lactams, which inhibit the transpeptidase activity of penicillin-binding proteins to decrease the cross-linking of peptidoglycan and the strength of the cell wall. While β-lactam antibiotics have historically proven to be effective, resistance to β-lactams is a growing problem. The ECF σ factor σ P is required for β-lactam resistance in B. thuringiensis and close relatives, including B. anthracis Here, we provide insight into the mechanism of activation of σ P by β-lactams., (Copyright © 2021 Nauta et al.)

In Bacillus thuringiensis, β-lactam antibiotic resistance is controlled by the extracytoplasmic function (ECF) σ factor σ P . σ P activity is inhibited by the anti-σ factor RsiP. In the presence of β-lactam antibiotics, RsiP is degraded and σ P is activated. Previous work found that RsiP degradation requires cleavage of RsiP at site 1 by an unknown protease, followed by cleavage at site 2 by the site 2 protease RasP. The penicillin-binding protein PbpP acts as a sensor for β-lactams. PbpP initiates σ P activation and is required for site 1 cleavage of RsiP but is not the site 1 protease. Here, we describe the identification of a signal peptidase, SipP, which cleaves RsiP at a site 1 signal peptidase cleavage site and is required for σ P activation. Finally, many B. anthracis strains are sensitive to β-lactams yet encode the σ P -RsiP signal transduction system. We identified a naturally occurring mutation in the signal peptidase cleavage site of B. anthracis RsiP that renders it resistant to SipP cleavage. We find that B. anthracis RsiP is not degraded in the presence of β-lactams. Altering the B. anthracis RsiP site 1 cleavage site by a single residue to resemble B. thuringiensis RsiP results in β-lactam-dependent degradation of RsiP. We show that mutation of the B. thuringiensis RsiP cleavage site to resemble the sequence of B. anthracis RsiP blocks degradation by SipP. The change in the cleavage site likely explains many reasons why B. anthracis strains are sensitive to β-lactams. IMPORTANCE β-Lactam antibiotics are important for the treatment of many bacterial infections. However, resistance mechanisms have become increasingly more prevalent. Understanding how β-lactam resistance is conferred and how bacteria control expression of β-lactam resistance is important for informing the future treatment of bacterial infections. σ P is an alternative σ factor that controls the transcription of genes that confer β-lactam resistance in Bacillus thuringiensis, Bacillus cereus, and Bacillus anthracis. Here, we identify a signal peptidase as the protease required for initiating activation of σ P by the degradation of the anti-σ factor RsiP. The discovery that the signal peptidase SipP is required for σ P activation highlights an increasing role for signal peptidases in signal transduction, as well as in antibiotic resistance.

Pseudoplatystoma punctifer is an Amazonian catfish highly appreciated for its high flesh quality, size, and commercial value. Its aquaculture is pursued to satisfy the demands of an increasing population in the region. However, knowledge of the nutritional needs during the early life stages is necessary for improving growth and reducing the incidence of cannibalism, factors that limit the success of its commercial farming. This study aimed at evaluating the influence of four diets containing different protein and lipid levels (30:15, 30:10, 45:15, or 45:10 in %) in the digestive physiology and performance of early juveniles. The results showed that the dietary protein:lipid as well as carbohydrate levels and ratios influenced differently the whole-body proximate composition, the digestive physiology and development, and hence growth and survival. The 45:15 diet promoted the best growth, survival, and the most rapid development of the digestive system, as shown at histological (higher number of hepatocytes, goblet cells in the anterior intestine and enterocytes in all intestinal portions, and longer folds in the posterior intestine), molecular (highest amylase , lipoprotein lipase , phospholipase , trypsinogen, and pepsinogen gene expression), and biochemical (highest lipase and pepsin activities and higher alkaline phosphatase:leucine alanine peptidase activity ratio) levels. Lipids were favored over carbohydrates as source of energy, with lipids promoting a protein-sparing effect at adequate energy:protein ratio. Carbohydrate content higher than 25% was excessive for this species, leading to unbalanced lipid metabolism and fat deposition in the liver.

There is a high international demand for timber from the genus Dipteryx, or "shihuahuaco" as it is known in Peru. Developing tools that allow the identification and discrimination of Dipteryx species is therefore important for supporting management of natural populations and to underpin legal trade of its timber. The objective of this study was the molecular characterization of Dipteryx species in the Peruvian Amazonia. Two plastid regions (cpDNA: trnH-psbA and matK) were sequenced and 11 microsatellite markers (nDNA) were genotyped for 32 individuals identified as Dipteryx charapilla, D. micrantha morphotype 1 and D. micrantha morphotype 2. Using the concatenated sequences of the plastid genes, we identified ten haplotypes that were not shared between the species or between the D. micrantha morphotypes. Haplotypic diversity was greater in D. micrantha morphotype 2 and D. charapilla than in D. micrantha morphotype 1, which presented only one haplotype with a wide distribution in Peru. The microsatellites allowed the discrimination of the same three clades and identified diagnostic alleles for each clade. These results allowed us to demonstrate that the two morphotypes of D. micrantha are different at both the plastid and nuclear markers, which supports the existence of three genetically distinct species in Peru. This study provides information for the genetic discrimination of Dipteryx species and emphasises the importance of conserving the genetic variability of this genus in the Peruvian Amazonia.

Bacteria can utilize alternative σ factors to regulate sets of genes in response to changes in the environment. The largest and most diverse group of alternative σ factors are the extracytoplasmic function (ECF) σ factors. σ P is an ECF σ factor found in Bacillus anthracis , Bacillus cereus , and Bacillus thuringiensis Previous work showed that σ P is induced by ampicillin, a β-lactam antibiotic, and required for resistance to ampicillin. However, it was not known how activation of σ P is controlled or what other antibiotics may activate σ P Here, we report that activation of σ P is specific to a subset of β-lactams and that σ P is required for resistance to these β-lactams. We demonstrate that activation of σ P is controlled by the proteolytic destruction of the anti-σ factor RsiP and that degradation of RsiP requires multiple proteases. Upon exposure to β-lactams, the extracellular domain of RsiP is cleaved by an unknown protease, which we predict cleaves at site-1. Following cleavage by the unknown protease, the N terminus of RsiP is further degraded by the site-2 intramembrane protease RasP. Our data indicate that RasP cleavage of RsiP is not the rate-limiting step in σ P activation. This proteolytic cascade leads to activation of σ P , which induces resistance to β-lactams likely via increased expression of β-lactamases. IMPORTANCE The discovery of antibiotics to treat bacterial infections has had a dramatic and positive impact on human health. However, shortly after the introduction of a new antibiotic, bacteria often develop resistance. The bacterial cell envelope is essential for cell viability and is the target of many of the most commonly used antibiotics, including β-lactam antibiotics. Resistance to β-lactams is often dependent upon β-lactamases. In B. cereus , B. thuringiensis , and some B. anthracis strains, the expression of some β-lactamases is inducible. This inducible β-lactamase expression is controlled by activation of an alternative σ factor called σ P Here, we show that β-lactam antibiotics induce σ P activation by degradation of the anti-σ factor RsiP., (Copyright © 2019 Ho et al.)