Brazilian red propolis reduces the adhesion of oral biofilm cells and the Toxoplasma gondii intracellular proliferation.

Infectious diseases remain as a significant cause of thousands of deaths annually worldwide. Therefore, this study aimed to investigate the antimicrobial and antiparasitic activity of the crude hydroalcoholic extract and compounds isolated from Brazilian Red Propolis (BRP) against oral pathogens and Toxoplasma gondii, using in vitro, in vivo and in silico approaches. Antimicrobial and synergistic activities were determined using the broth dilution method and the checkerboard assay, respectively. Antibiofilm activity was evaluated by staining with 2 % crystal violet and counting microorganisms. In vivo infection was carried out in Caenorhabditis elegans AU37 larvae and in silico analysis was performed using molecular docking simulations. The effect on growth modulation of T. gondii was evaluated through a ß-galactosidase colorimetric assay. Minimum Inhibitory Concentration values ranged from 3.12 to 400 µg/mL. Biofilm Minimum Inhibitory Concentration (MICB50) values ranged from 6.25 to 375 µg/mL, with a significant reduction in the number of viable cells. Furthermore, Guttiferone E and the crude extract reduced cell aggregation and caused damage to the biofilm cell wall. The highest concentrations of the crude extract and Guttiferone E increased the survival and reduced the risk of death of infected and treated larvae. Guttiferone E and Oblongifolin B inhibited the intracellular proliferation of T. gondii and demonstrated several targets of action against bacteria and T. gondii through in silico analysis. These data demonstrate that BRP has antimicrobial and antiparasitic activity against pathogens of clinical relevance, and can be used in the future as phytomedicines.

Distinct functions of three Wnt proteins control mirror-symmetric organogenesis in the C. elegans gonad.

Organogenesis requires the proper production of diverse cell types and their positioning/migration. However, the coordination of these processes during development remains poorly understood. The gonad in C. elegans exhibits a mirror-symmetric structure guided by the migration of distal tip cells (DTCs), which result from asymmetric divisions of somatic gonadal precursors (SGPs; Z1 and Z4). We found that the polarity of Z1 and Z4, which possess mirror-symmetric orientation, is controlled by the redundant functions of the LIN-17/Frizzled receptor and three Wnt proteins (CWN-1, CWN-2, and EGL-20) with distinct functions. In lin-17 mutants, CWN-2 promotes normal polarity in both Z1 and Z4, while CWN-1 promotes reverse and normal polarity in Z1 and Z4, respectively. In contrast, EGL-20 inhibits the polarization of both Z1 and Z4. In lin-17 egl-20 cwn-2 triple mutants with a polarity reversal of Z1, DTCs from Z1 frequently miss-migrate to the posterior side. Our further analysis demonstrates that the mis-positioning of DTCs in the gonad due to the polarity reversal of Z1 leads to mis-migration. Similar mis-migration was also observed in cki-1(RNAi) animals producing ectopic DTCs. These results highlight the role of Wnt signaling in coordinating the production and migration of DTCs to establish a mirror-symmetric organ.

Calcineurin inhibition enhances Caenorhabditis elegans lifespan by defecation defects-mediated calorie restriction and nuclear hormone signaling.

Calcineurin is a highly conserved calcium/calmodulin-dependent serine/threonine protein phosphatase with diverse functions. Inhibition of calcineurin is known to enhance the lifespan of Caenorhabditis elegans through multiple signaling pathways. Aiming to study the role of calcineurin in regulating innate immunity, we discover that calcineurin is required for the rhythmic defecation motor program (DMP) in C. elegans. Calcineurin inhibition leads to defects in the DMP, resulting in intestinal bloating, rapid colonization of the gut by bacteria, and increased susceptibility to bacterial infection. We demonstrate that intestinal bloating caused by calcineurin inhibition mimics the effects of calorie restriction, resulting in enhanced lifespan. The TFEB ortholog, HLH-30, is required for lifespan extension mediated by calcineurin inhibition. Finally, we show that the nuclear hormone receptor, NHR-8, is upregulated by calcineurin inhibition and is necessary for the increased lifespan. Our studies uncover a role for calcineurin in the C. elegans DMP and provide a new mechanism for calcineurin inhibition-mediated longevity extension.

Many research efforts currently focus on identifying the dietary, pharmacological or genetic interventions that could help to prolong life. In the process, these investigations often uncover complex or even unexpected relationships between a range of physiological processes. The link between longevity and the immune system, for example, is yet to be fully understood. To explore these dynamics, Das et al. focused on calcineurin, an enzyme present in organisms across the tree of life. In humans, calcineurin is known to regulate a set of proteins essential for the immune response; these proteins are absent in the microscopic worm Caenorhabditis elegans, in which inhibiting calcineurin extends lifespan. Investigating how calcineurin inhibition impacts the immune system of C. elegans therefore presents a unique opportunity to better understand the complex links between immunity and longevity. Experiments conducted on worms genetically modified to lack calcineurin showed that these animals lived longer than their 'normal' counterparts, but that they were also more susceptible to infection when exposed to a harmful species of bacteria. Further experiments showed that the enzyme was crucial for regulating defecation in C. elegans. Without calcineurin, the worms became bloated and constipated; they could not properly eliminate bacteria, which could then proliferate in the digestive system and cause issues. However, intestinal bloating also activated signalling pathways normally triggered by calorie restriction ­ an intervention well-known for extending the lifespan of various species. Taken together, the findings by Das et al. help explain why calcineurin inhibition in C. elegans leads to opposite effects on longevity and resistance to infection. They also align with a recent body of work showing the profound effect of gut bloating on food-seeking behaviors, immunity and lifespan. Further investigations into these mechanisms may one day uncover new ways to improve human health.

The TOP-2/condensin II axis silences transcription during germline specification in C. elegans.

In C. elegans, the germline is specified via a preformation mechanism that relies on the PIE-1 protein's ability to globally silence mRNA transcription in germline precursor cells, also known as the P lineage. Recent work from our group has identified additional genome silencing events in C. elegans during oogenesis and in starved L1 larvae, and these require the condensin II complex, topoisomerase II (TOP-2), and components of the H3K9me/heterochromatin pathway. Interestingly, silencing in oocytes also requires PIE-1, but this is not the case in starved L1s. Here, we ask if additional genome silencing components besides PIE-1 are required to repress gene expression in the P lineage of early embryos, and we find that condensin II and TOP-2 are required and the H3K9me/heterochromatin pathway is not. We show that depletion of TOP-2/condensin II activates the normally suppressed RNA polymerase II to inappropriately transcribe somatic genes in the P lineage. We also present evidence that while both PIE-1 and TOP-2/condensin II are required for genome silencing in the P lineage, PIE-1 can silence transcription independently of TOP-2/condensin II when misexpressed in somatic cells. Thus, in oocytes, all three genome silencing systems (TOP-2/condensin II, H3K9me, and PIE-1) are operational while in both early embryos and starved L1s two of the three are active. Our data show that multiple, redundantly acting genome silencing mechanisms act in a mix and match manner to repress transcription at different developmental stages in the C. elegans germline.

Investigating the impact of ketogenic diets.

Exposure to ketone bodies in early development can reduce neurological impairments in a strain of the nematode C. elegans with PTEN defects.

A mitochondrial unfolded protein response-independent role of DVE-1 in longevity regulation.

The special AT-rich sequence-binding (SATB) protein DVE-1 is widely recognized for its pivotal involvement in orchestrating the retrograde mitochondrial unfolded protein response (mitoUPR) in C. elegans. In our study of downstream factors contributing to lifespan extension in sensory ciliary mutants, we find that DVE-1 is crucial for this longevity effect independent of its canonical mitoUPR function. Additionally, DVE-1 also influences lifespan under conditions of dietary restriction and germline loss, again distinct from its role in mitoUPR. Mechanistically, while mitochondrial stress typically prompts nuclear accumulation of DVE-1 to initiate the transcriptional mitoUPR program, these long-lived mutants reduce DVE-1 nuclear accumulation, likely by enhancing its cytosolic translocation. This observation suggests a cytosolic role for DVE-1 in lifespan extension. Overall, our study implies that, in contrast to the more narrowly defined role of the mitoUPR-related transcription factor ATFS-1, DVE-1 may possess broader functions than previously recognized in modulating longevity and defending against stress.

A FMRFamide-like neuropeptide FLP-12 signaling regulates head locomotive behaviors in C. elegans.

Neuropeptides play a critical role in regulating behaviors across organisms, but the precise mechanisms by which neuropeptides orchestrate complex behavioral programs are not fully understood. Here, we show that the FMRFamide-like neuropeptide FLP-12 signaling from the SMB head motor neurons, modulates head locomotive behaviors, including stomatal oscillation in C. elegans. lim-4 mutants, in which the SMB neurons are not properly specified, exhibited various head and body locomotive defects, including stomatal oscillation. Chronic activation or inhibition of neuropeptidergic signaling in the SMB motor neurons resulted in a decrease or increase in stomatal oscillation, respectively. The flp-12 neuropeptide gene is expressed and acts in the SMB neurons to regulate head and body locomotion, including stomatal oscillation. Moreover, the frpr-8 GPCR and gpa-7 Gα genes are expressed in the AVD command interneurons to relay the FLP-12 signal to mediate stomatal oscillation. Finally, heterologous expression of FRPR-8 either Xenopus oocytes or HEK293T cells conferred FLP-12 induced responses. Taken together, these results indicate that the C. elegans FMRFamide neuropeptide FLP-12 acts as a modulator of stomatal oscillation via the FRPR-8 GPCR and the GPA-7 G-protein.

A role for organ level dynamics in morphogenesis of the C. elegans hermaphrodite distal tip cell.

The morphology of cells in vivo can arise from a variety of mechanisms. In the Caenorhabditis elegans hermaphrodite gonad, the distal tip cell (DTC) elaborates into a complex plexus over a relatively short developmental time period, but the mechanisms underlying this change in cell morphology are not well defined. We correlated the time of DTC elaboration with the L4-to-adult molt, but ruled out a relevant heterochronic pathway as a cue for DTC elaboration. Instead, we found that the timing of gonad elongation and aspects of underlying germline flux influence DTC elaboration. We propose a 'hitch and tow' aspect of organ-level dynamics that contributes to cellular morphogenesis, whereby germline flux drags the flexible DTC cell cortex away from its stationary cell body. More broadly, we speculate that this mechanism may contribute to cell shape changes in other contexts with implications for development and disease.

Bisphenol S decreased lifespan and healthspan via insulin/IGF-1-like signaling-against mitochondrial stress in Caenorhabditis elegans.

Bisphenol S (BPS) is widely presented and affects aging with unclear mechanisms. Here, we applied C. elegans to evaluate the effects of BPS on lifespan and healthspan and to investigate the underlying mechanisms. Both early-life and whole-life exposure to BPS at environmentally relevant doses (0.6, 6, 60 µg/L) significantly decreased lifespan, and healthspan (body bend, pharyngeal pumping, and lipofuscin accumulation). BPS exposure impaired mitochondrial structure and function, which promoted ROS production to induce oxidative stress. Furthermore, BPS increased expressions of the insulin/IGF-like signaling (IIS). Also, BPS inhibited expression of the IIS transcription factor daf-16 and its downstream anti-oxidative genes. Quercetin effectively improved BPS-induced oxidative stress byreversing BPS-regulated IIS/daf-16 pathway and anti-oxidative gene expressions. In daf-2 and daf-16 mutants, the effects of BPS and quercetin on lifespan, healthspan, oxidative stress, and anti-oxidative genes expressions were reversed, demonstrating the requirement of IIS/daf-16 for aging regulation. Molecular docking and molecular dynamics simulations confirmed the stable interaction between DAF-2 and BPS mainly via three residues (VAL1260, GLU1329, and MET1395), which was attenuated by quercetin. Our results highlighted that adverse effects of BPS on impairing lifespan and healthspan by affecting IIS/daf-16 function against mitochondrial stress, which could be inhibited by quercetin treatment. Thus, we first revealed the underlying mechanisms of BPS-induced aging and the potential treatment.

Neural Circuit Remodeling: Mechanistic Insights from Invertebrates.

As nervous systems mature, neural circuit connections are reorganized to optimize the performance of specific functions in adults. This reorganization of connections is achieved through a remarkably conserved phase of developmental circuit remodeling that engages neuron-intrinsic and neuron-extrinsic molecular mechanisms to establish mature circuitry. Abnormalities in circuit remodeling and maturation are broadly linked with a variety of neurodevelopmental disorders, including autism spectrum disorders and schizophrenia. Here, we aim to provide an overview of recent advances in our understanding of the molecular processes that govern neural circuit remodeling and maturation. In particular, we focus on intriguing mechanistic insights gained from invertebrate systems, such as the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster. We discuss how transcriptional control mechanisms, synaptic activity, and glial engulfment shape specific aspects of circuit remodeling in worms and flies. Finally, we highlight mechanistic parallels across invertebrate and mammalian systems, and prospects for further advances in each.

Length-sensitive partitioning of Caenorhabditiselegans meiotic chromosomes responds to proximity and number of crossover sites.

Sensing and control of size are critical for cellular function and survival. A striking example of size sensing occurs during meiosis in the nematode Caenorhabditis elegans. C. elegans chromosomes compare the lengths of the two chromosome "arms" demarcated by the position of their single off-center crossover, and they differentially modify these arms to ensure that sister chromatid cohesion is lost specifically on the shorter arm in the first meiotic division, while the longer arm maintains cohesion until the second division. While many of the downstream steps leading to cohesion loss have been characterized, the length-sensing process itself remains poorly understood. Here, we have used cytological visualization of short and long chromosome arms, combined with quantitative microscopy, live imaging, and simulations, to investigate the principles underlying length-sensitive chromosome partitioning. By quantitatively analyzing short-arm designation patterns on fusion chromosomes carrying multiple crossovers, we develop a model in which a short-arm-determining factor originates at crossover designation sites, diffuses within the synaptonemal complex, and accumulates within crossover-bounded chromosome segments. We demonstrate experimental support for a critical assumption of this model: that crossovers act as boundaries to diffusion within the synaptonemal complex. Further, we develop a discrete simulation based on our results that recapitulates a wide variety of observed partitioning outcomes in both wild-type and previously reported mutants. Our results suggest that the concentration of a diffusible factor is used as a proxy for chromosome length, enabling the correct designation of short and long arms and proper segregation of chromosomes.

The ketone body ß-hydroxybutyrate ameliorates neurodevelopmental deficits in the GABAergic system of daf-18/PTEN Caenorhabditis elegans mutants.

A finely tuned balance between excitation and inhibition (E/I) is essential for proper brain function. Disruptions in the GABAergic system, which alter this equilibrium, are a common feature in various types of neurological disorders, including autism spectrum disorders (ASDs). Mutations in Phosphatase and Tensin Homolog (PTEN), the main negative regulator of the phosphatidylinositol 3-phosphate kinase/Akt pathway, are strongly associated with ASD. However, it is unclear whether PTEN deficiencies can differentially affect inhibitory and excitatory signaling. Using the Caenorhabditis elegans neuromuscular system, where both excitatory (cholinergic) and inhibitory (GABAergic) inputs regulate muscle activity, we found that daf-18/PTEN mutations impact GABAergic (but not cholinergic) neurodevelopment and function. This selective impact results in a deficiency in inhibitory signaling. The defects observed in the GABAergic system in daf-18/PTEN mutants are due to reduced activity of DAF-16/FOXO during development. Ketogenic diets (KGDs) have proven effective for disorders associated with E/I imbalances. However, the mechanisms underlying their action remain largely elusive. We found that a diet enriched with the ketone body ß-hydroxybutyrate during early development induces DAF-16/FOXO activity, therefore improving GABAergic neurodevelopment and function in daf-18/PTEN mutants. Our study provides valuable insights into the link between PTEN mutations and neurodevelopmental defects and delves into the mechanisms underlying the potential therapeutic effects of KGDs.

To work optimally, the brain needs to delicately balance excitation and inhibition ­ that is, it must precisely control exactly when and how excitatory neurons (which activate the system) or inhibitory ones (which counteract these activating signals) are switched on. Neurological disorders can arise when this equilibrium is disrupted, for example when defects are present in an inhibitory signalling system that relies on a molecule known as GABA. More recently, a gene known as PTEN has also emerged as playing an important role during the development of the nervous system, yet exactly why this is the case has remained unclear. To explore this question, Giunti et al. focused on the neuromuscular system of the roundworm Caenorhabditis elegans, in which excitatory ('cholinergic') and inhibitory ('GABAergic') neurons control how muscles contract and relax. A range of biological approaches were used to assess the impact of PTEN deficiencies on this system. This revealed that mutations in this gene do not impact cholinergic activity; they did, however, lead to diminished GABAergic activity. Overall, this resulted in an increased ratio of excitatory to inhibitory activity in the system. Further work showed that, in the mutated worms, the suppression of inhibitory neurons was due to a specific protein being inactive during early development. This transcription factor is the worm equivalent of the human FOXO protein, and it helps to turn genes on and off during development. Its inactivity is linked to noticeable changes in the shape and activity of GABAergic neurons. In humans, medical ketogenic diets (which force the body to use fats rather than sugars as a source of energy) are known to improve conditions linked to imbalances in the excitatory and inhibitory systems. Giunti et al. therefore investigated whether a similar approach could mitigate some of the defects seen in PTEN mutants. Exposing these worms early in development to a type of molecule produced in ketogenic diets partly improved the state of their GABAergic neurons. Taken together, this work suggests a potential molecular basis for the association between PTEN and the balance between excitatory and inhibitory activity. As PTEN mutations are often found in individuals diagnosed with autism spectrum disorders, further research is necessary to validate these findings in mammals and explore their clinical relevance.

A neurotransmitter atlas of C. elegans males and hermaphrodites.

Mapping neurotransmitter identities to neurons is key to understanding information flow in a nervous system. It also provides valuable entry points for studying the development and plasticity of neuronal identity features. In the Caenorhabditis elegans nervous system, neurotransmitter identities have been largely assigned by expression pattern analysis of neurotransmitter pathway genes that encode neurotransmitter biosynthetic enzymes or transporters. However, many of these assignments have relied on multicopy reporter transgenes that may lack relevant cis-regulatory information and therefore may not provide an accurate picture of neurotransmitter usage. We analyzed the expression patterns of 16 CRISPR/Cas9-engineered knock-in reporter strains for all main types of neurotransmitters in C. elegans (glutamate, acetylcholine, GABA, serotonin, dopamine, tyramine, and octopamine) in both the hermaphrodite and the male. Our analysis reveals novel sites of expression of these neurotransmitter systems within both neurons and glia, as well as non-neural cells, most notably in gonadal cells. The resulting expression atlas defines neurons that may be exclusively neuropeptidergic, substantially expands the repertoire of neurons capable of co-transmitting multiple neurotransmitters, and identifies novel sites of monoaminergic neurotransmitter uptake. Furthermore, we also observed unusual co-expression patterns of monoaminergic synthesis pathway genes, suggesting the existence of novel monoaminergic transmitters. Our analysis results in what constitutes the most extensive whole-animal-wide map of neurotransmitter usage to date, paving the way for a better understanding of neuronal communication and neuronal identity specification in C. elegans.

Zein nanoparticles extend lifespan in C. elegans and SAMP8 mice.

Empty zein nanoparticles (NP) have been shown to lower glycemia in rats by stimulating the secretion of endogenous GLP-1. This study evaluated the effect of these nanoparticles on the lifespan of two animal models: C. elegans fed with a glucose-rich diet and the senescence accelerated mouse-prone 8 (SAMP8 mice). In C. elegans, NP increased the mean lifespan of worms by 7 days (from 17.1 for control to 24.5 days). This observation was in line with the observed significant reductions of glucose and fat contents, lipofuscin accumulation, and ROS expression. Furthermore, NP supplementation led to an upregulation of the expression of daf-16 and skn-1 genes. DAF-16 (orthologue of the FOXO family) and SKN-1 (orthologue of mammalian Nrf/CNC proteins) are implicated in activating detoxification mechanisms against oxidative damage. In SAMP8, oral administration of NP also extended the mean lifespan of mice (by 28 % compared to controls), corroborating the protective effect of these nanoparticles.

Global analysis of neuropeptide receptor conservation across phylum Nematoda.

BACKGROUND: The phylum Nematoda is incredibly diverse and includes many parasites of humans, livestock, and plants. Peptide-activated G protein-coupled receptors (GPCRs) are central to the regulation of physiology and numerous behaviors, and they represent appealing pharmacological targets for parasite control. Efforts are ongoing to characterize the functions and define the ligands of nematode GPCRs, with already most peptide GPCRs known or predicted in Caenorhabditis elegans. However, comparative analyses of peptide GPCR conservation between C. elegans and other nematode species are limited, and many nematode GPCRs remain orphan. A phylum-wide perspective on peptide GPCR profiles will benefit functional and applied studies of nematode peptide GPCRs. RESULTS: We constructed a pan-phylum resource of C. elegans peptide GPCR orthologs in 125 nematode species using a semi-automated pipeline for analysis of predicted proteome datasets. The peptide GPCR profile varies between nematode species of different phylogenetic clades and multiple C. elegans peptide GPCRs have orthologs across the phylum Nematoda. We identified peptide ligands for two highly conserved orphan receptors, NPR-9 and NPR-16, that belong to the bilaterian galanin/allatostatin A (Gal/AstA) and somatostatin/allatostatin C (SST/AstC) receptor families. The AstA-like NLP-1 peptides activate NPR-9 in cultured cells and are cognate ligands of this receptor in vivo. In addition, we discovered an AstC-type peptide, NLP-99, that activates the AstC-type receptor NPR-16. In our pan-phylum resource, the phylum-wide representation of NPR-9 and NPR-16 resembles that of their cognate ligands more than those of allatostatin-like peptides that do not activate these receptors. CONCLUSIONS: The repertoire of C. elegans peptide GPCR orthologs varies across phylogenetic clades and several peptide GPCRs show broad conservation in the phylum Nematoda. Our work functionally characterizes the conserved receptors NPR-9 and NPR-16 as the respective GPCRs for the AstA-like NLP-1 peptides and the AstC-related peptide NLP-99. NLP-1 and NLP-99 are widely conserved in nematodes and their representation matches that of their receptor in most species. These findings demonstrate the conservation of a functional Gal/AstA and SST/AstC signaling system in nematodes. Our dataset of C. elegans peptide GPCR orthologs also lays a foundation for further functional studies of peptide GPCRs in the widely diverse nematode phylum.

Paeoniflorin alleviates toxicity and accumulation of 6-PPD quinone by activating ACS-22 in Caenorhabditis elegans.

6-PPD quinone (6-PPDQ) is extensively existed in various environments. In Caenorhabditis elegans, exposure to 6-PPDQ could cause multiple toxic effects. In the current study, we further used C. elegans to investigate the effect of paeoniflorin (PF) treatment on 6-PPDQ toxicity and accumulation and the underlying mechanism. Treatment with PF (25-100 mg/L) inhibited 6-PPDQ toxicity on reproduction capacity and locomotion behavior and in inducing reactive oxygen species (ROS) production. Additionally, PF (25-100 mg/L) alleviated the dysregulation in expression of genes governing oxidative stress caused by 6-PPDQ exposure. Moreover, PF (25-100 mg/L) inhibited the enhancement in intestinal permeability caused by 6-PPDQ exposure and the accumulation of 6-PPDQ in the body of nematodes. In 6-PPDQ exposed nematodes, PF (25-100 mg/L) increased expression of acs-22 encoding a fatty acid transporter. RNAi of acs-22 could inhibit the beneficial effect of PF against 6-PPDQ toxicity in decreasing reproductive capacity and locomotion behavior, in inducing intestinal ROS production, and in enhancing intestinal permeability. RNAi of acs-22 could also suppress the PF beneficial effect against 6-PPDQ accumulation in the body of nematodes. Therefore, our results demonstrate the function of PF treatment against 6-PPDQ toxicity and accumulation in nematodes by activating the ACS-22.

Visualizing genomic evolution in Caenorhabditis through WormSynteny.

Understanding the syntenic relationships among genomes is crucial to elucidate the genomic mechanisms that drive the evolution of species. The nematode Caenorhabditis is a good model for studying genomic evolution due to the well-established biology of Caenorhabditis elegans and the availability of > 50 genomes in the genus. However, effective alignment of more than ten species in Caenorhabditis has not been conducted before, and there is currently no tool to visualize the synteny of more than two species. In this study, we used Progressive Cactus, a recently developed multigenome aligner, to align the genomes of eleven Caenorhabditis species. Through the progressive alignment, we reconstructed nine ancestral genomes, analyzed the mutational types that cause genomic rearrangement during speciation, and found that insertion and duplication are the major driving forces for genome expansion. Dioecious species appear to expand their genomes more than androdioecious species. We then built an online interactive app called WormSynteny to visualize the syntenic relationship among the eleven species. Users can search the alignment dataset using C. elegans query sequences, construct synteny plots at different genomic scales, and use a set of options to control alignment output and plot presentation. We showcased the use of WormSynteny to visualize the syntenic conservation of one-to-one orthologues among species, tandem and dispersed gene duplication in C. elegans, and the evolution of exon and intron structures. Importantly, the integration of orthogroup information with synteny linkage in WormSynteny allows the easy visualization of conserved genomic blocks and disruptive rearrangement. In conclusion, WormSynteny provides immediate access to the syntenic relationships among the most widely used Caenorhabditis species and can facilitate numerous comparative genomics studies. This pilot study with eleven species also serves as a proof-of-concept to a more comprehensive larger-scale analysis using hundreds of nematode genomes, which is expected to reveal mechanisms that drive genomic evolution in the Nematoda phylum. Finally, the WormSynteny software provides a generalizable solution for visualizing the output of Progressive Cactus with interactive graphics, which would be useful for a broad community of genome researchers.

Salmonella biofilm formation diminishes bacterial proliferation in the C. elegans intestine.

Non-typhoidal Salmonella serovars are a significant global cause of foodborne infections, owing their transmission success to the formation of biofilms. While the role of these biofilms in Salmonella's persistence outside the host is well understood, their significance during infection remains elusive. In this study, we investigated the impact of Salmonella biofilm formation on host colonization and virulence using the nematode model Caenorhabditis elegans. This infection model enables us to isolate the effect of biofilm formation on gut colonization and proliferation, as no gut microbiome is present and Salmonella cannot invade the intestinal tissue of the nematode. We show that a biofilm-deficient ΔcsgD mutant enhances gut proliferation compared to the wild-type strain, while the pathogen's virulence, the host's immune signaling pathways, and host survival remain unaffected. Hence, our work suggests that biofilm formation does not significantly contribute to Salmonella infection in C. elegans. However, complementary assays in higher-order in vivo models are required to further characterize the role of biofilm formation during infection and to take into account the impact of biofilm formation on competition with gut microbiome and epithelial invasion.

Tensions on the actin cytoskeleton and apical cell junctions in the C. elegans spermatheca are influenced by spermathecal anatomy, ovulation state and activation of myosin.

Introduction: Cells generate mechanical forces mainly through myosin motor activity on the actin cytoskeleton. In C. elegans, actomyosin stress fibers drive contractility of the smooth muscle-like cells of the spermatheca, a distensible, tube-shaped tissue in the hermaphrodite reproductive system and the site of oocyte fertilization. Stretching of the spermathecal cells by oocyte entry triggers activation of the small GTPase Rho. In this study, we asked how forces are distributed in vivo, and explored how spermathecal tissue responds to alterations in myosin activity. Methods: In animals expressing GFP labeled actin or apical membrane complexes, we severed these structures using femtosecond laser ablation and quantified retractions. RNA interference was used to deplete key contractility regulators. Results: We show that the basal actomyosin fibers are under tension in the occupied spermatheca. Reducing actomyosin contractility by depletion of the phospholipase C-ε/PLC-1 or non-muscle myosin II/NMY-1, leads to distended spermathecae occupied by one or more embryos, but does not alter tension on the basal actomyosin fibers. However, activating myosin through depletion of the Rho GAP SPV-1 increases tension on the actomyosin fibers, consistent with earlier studies showing Rho drives spermathecal contractility. On the inner surface of the spermathecal tube, tension on the apical junctions is decreased by depletion of PLC-1 and NMY-1. Surprisingly, when basal contractility is increased through SPV-1 depletion, the tension on apical junctions also decreases, with the most significant effect on the junctions aligned in perpendicular to the axis of the spermatheca. Discussion: Our results suggest that much of the tension on the basal actin fibers in the occupied spermatheca is due to the presence of the embryo. Additionally, increased tension on the outer basal surface may compress the apical side, leading to lower tensions apically. The three dimensional shape of the spermatheca plays a role in force distribution and contractility during ovulation.

Elucidating the effective age for dietary restriction and the key metabolites involved.

Dietary restriction (DR) extends lifespan in various species, but its effect at different ages, especially when started later, is unclear. This study used Caenorhabditis elegans to explore the impact of DR at different ages. Worms were divided into control and DR groups, with daily survival monitored. To confirm the occurrence of DR, the expression of DR-sensitive genes namely acdh-1, pyk-1, pck-2 and cts-1 were determined using RT-qPCR. Liquid chromatography mass spectrometry (LC-MS) was employed to observe the changes in metabolites affected by DR. The results indicated that young worms subjected to mild DR displayed the longest lifespan, highlighting the effectiveness of initiating DR at a young age. Increased expression of acdh-1 and pck-2 suggests activation of beta-oxidation and gluconeogenesis, while decreased cts-1 expression indicates a reduced citric acid cycle, further supporting the observed effects of DR in these worms. Metabolomic results indicated that DR decreased the activity of mechanistic Target of Rapamycin (mTOR) and the synthesis of amino acids namely leucine, tyrosine and tryptophan to conserve energy for cell repair and survival. DR also decreased levels of N-acetyl-L-methionine and S-adenosyl-methionine (SAM) in methionine metabolism, thereby promoting autophagy, reducing inflammation, and facilitating the removal of damaged cells and proteins. In conclusion, initiating dietary restriction early in life extends the lifespan by modulating amino acid metabolism and enhancing the autophagy pathway, thereby maintaining cellular wellbeing.