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Parkinson's disease (PD) is a common neurodegenerative disorder characterized by symptoms such as bradykinesia, resting tremor, and rigidity, primarily driven by the degradation of dopaminergic (DA) neurons in the substantia nigra. A significant contributor to familial autosomal dominant PD cases is mutations in the LRRK2 gene, making it a primary therapeutic target. This study explores the role of microRNAs (miRNAs) in regulating the proteomic stress responses associated with neurodegeneration in PD using C. elegans models. Our focus is on miR-71, a miRNA known to affect stress resistance and act as a pro-longevity factor in C. elegans. We investigated miR-71's function in C. elegans models of PD, where mutant LRRK2 expression correlates with dopaminergic neuronal death. Our findings reveal that miR-71 overexpression rescues motility defects and slows dopaminergic neurodegeneration in these models, suggesting its critical role in mitigating the proteotoxic effects of mutant LRRK2. Conversely, miR-71 knockout exacerbates neuronal death caused by mutant LRRK2. Additionally, our data indicate that miR-71's neuroprotective effect involves downregulating the toll receptor domain protein tir-1, implicating miR-71 repression of tir-1 as vital in the response to LRRK2-induced proteotoxicity. These insights into miR-71's role in C. elegans models of PD not only enhance our understanding of molecular mechanisms in neurodegeneration but also pave the way for potential research into human neurodegenerative diseases, leveraging the conservation of miRNAs and their targets across species. [ABSTRACT FROM AUTHOR]

Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by symptoms such as bradykinesia, resting tremor, and rigidity, primarily driven by the degradation of dopaminergic (DA) neurons in the substantia nigra. A significant contributor to familial autosomal dominant PD cases is mutations in the LRRK2 gene, making it a primary therapeutic target. This study explores the role of microRNAs (miRNAs) in regulating the proteomic stress responses associated with neurodegeneration in PD using C. elegans models. Our focus is on miR-71, a miRNA known to affect stress resistance and act as a pro-longevity factor in C. elegans. We investigated miR-71’s function in C. elegans models of PD, where mutant LRRK2 expression correlates with dopaminergic neuronal death. Our findings reveal that miR-71 overexpression rescues motility defects and slows dopaminergic neurodegeneration in these models, suggesting its critical role in mitigating the proteotoxic effects of mutant LRRK2. Conversely, miR-71 knockout exacerbates neuronal death caused by mutant LRRK2. Additionally, our data indicate that miR-71’s neuroprotective effect involves downregulating the toll receptor domain protein tir-1, implicating miR-71 repression of tir-1 as vital in the response to LRRK2-induced proteotoxicity. These insights into miR-71’s role in C. elegans models of PD not only enhance our understanding of molecular mechanisms in neurodegeneration but also pave the way for potential research into human neurodegenerative diseases, leveraging the conservation of miRNAs and their targets across species.

The auxin-inducible degradation system in C. elegans allows for spatial and temporal control of protein degradation via heterologous expression of a single Arabidopsis thaliana F-box protein, transport inhibitor response 1 (AtTIR1). In this system, exogenous auxin (Indole-3-acetic acid; IAA) enhances the ability of AtTIR1 to function as a substrate recognition component that adapts engineered degron-tagged proteins to the endogenous C. elegans E3 ubiquitin ligases complex [SKR-1/2-CUL-1-F-box (SCF)], targeting them for degradation by the proteosome. While this system has been employed to dissect the developmental functions of many C. elegans proteins, we have found that several auxin-inducible degron (AID)-tagged proteins are constitutively degraded by AtTIR1 in the absence of auxin, leading to undesired loss-of-function phenotypes. In this manuscript, we adapt an orthogonal auxin derivative/mutant AtTIR1 pair [C. elegans AID version 2 (C.e.AIDv2)] that transforms the specificity of allosteric regulation of TIR1 from IAA to one that is dependent on an auxin derivative harboring a bulky aryl group (5-Ph-IAA). We find that a mutant AtTIR1(F79G) allele that alters the ligand-binding interface of TIR1 dramatically reduces ligand-independent degradation of multiple AID*-tagged proteins. In addition to solving the ectopic degradation problem for some AID-targets, the addition of 5-Ph-IAA to culture media of animals expressing AtTIR1(F79G) leads to more penetrant loss-of-function phenotypes for AID*-tagged proteins than those elicited by the AtTIR1-IAA pairing at similar auxin analog concentrations. The improved specificity and efficacy afforded by the mutant AtTIR1(F79G) allele expand the utility of the AID system and broaden the number of proteins that can be effectively targeted with it.

Microsporidia are ubiquitous obligate intracellular pathogens of animals. These parasites often infect hosts through an oral route, but little is known about the function of host intestinal proteins that facilitate microsporidia invasion. To identify such factors necessary for infection by Nematocida parisii, a natural microsporidian pathogen of Caenorhabditis elegans, we performed a forward genetic screen to identify mutant animals that have a Fitness Advantage with Nematocida (Fawn). We isolated four fawn mutants that are resistant to Nematocida infection and contain mutations in T14E8.4, which we renamed aaim-1 (Antibacterial and Aids invasion by Microsporidia). Expression of AAIM-1 in the intestine of aaim-1 animals restores N. parisii infectivity and this rescue of infectivity is dependent upon AAIM-1 secretion. N. parisii spores in aaim-1 animals are improperly oriented in the intestinal lumen, leading to reduced levels of parasite invasion. Conversely, aaim-1 mutants display both increased colonization and susceptibility to the bacterial pathogen Pseudomonas aeruginosa and overexpression ofaaim-1 reduces P. aeruginosa colonization. Competitive fitness assays show that aaim-1 mutants are favored in the presence of N. parisii but disadvantaged on P. aeruginosa compared to wild-type animals. Together, this work demonstrates how microsporidia exploits a secreted protein to promote host invasion. Our results also suggest evolutionary trade-offs may exist to optimizing host defense against multiple classes of pathogens.

TMEM132D is a human gene identified with multiple risk alleles for panic disorders, anxiety and major depressive disorders. Defining a conserved family of transmembrane proteins, TMEM132D and its homologs are still of unknown molecular functions. By generating loss-of-function mutants of the sole TMEM132 ortholog in C. elegans, we identify abnormal morphologic phenotypes in the dopaminergic PDE neurons. Using a yeast two-hybrid screen, we find that NAP1 directly interacts with the cytoplasmic domain of human TMEM132D, and mutations in C. elegans tmem-132 that disrupt interaction with NAP1 cause similar morphologic defects in the PDE neurons. NAP1 is a component of the WAVE regulatory complex (WRC) that controls F-actin cytoskeletal dynamics. Decreasing activity of WRC rescues the PDE defects in tmem-132 mutants, whereas gain-of-function of TMEM132D in mammalian cells inhibits WRC, leading to decreased abundance of select WRC components, impaired actin nucleation and cell motility. We propose that metazoan TMEM132 family proteins play evolutionarily conserved roles in regulating NAP1 protein homologs to restrict inappropriate WRC activity, cytoskeletal and morphologic changes in the cell.

In the nematode Caenorhabditis elegans, signals derived from bacteria in the diet, the animal's major nutrient source, can modulate both behavior and healthspan. Here we describe a dual role for trimethylamine (TMA), a human gut flora metabolite, which acts as a nutrient signal and a neurotoxin. TMA and its associated metabolites are produced by the human gut microbiome and have been suggested to serve as risk biomarkers for diabetes and cardiovascular diseases. We demonstrate that the tyramine receptor TYRA-3, a conserved G protein-coupled receptor (GPCR), is required to sense TMA and mediate its responses. TMA activates guanylyl cyclase DAF-11 signaling through TYRA-3 in amphid neurons (ASK) and ciliated neurons (BAG) to mediate food-sensing behavior. Bacterial mutants deficient in TMA production enhance dauer formation, extend lifespan, and are less preferred as a food source. Increased levels of TMA lead to neural damage in models of Parkinson's disease and shorten lifespan. Our results reveal conserved signaling pathways modulated by TMA in C. elegans that are likely to be relevant for its effects in mammalian systems.

Objective This research aimed to identify Fusariums belonging to Elegans and Martiella-Ventricosum sections related to cucurbit plants in Tehran province and to evaluate the ability of ISSR markers to investigate the kinship relationships of these groups of Fusariums. Materials and methods In this research, five ISSR primers (AG)8C, (AG)8G, (AC)8YA, (ATG)6 and BHB(GA)7 were selected. Fungal isolates identified based on morphological and microscopic characteristics. For ISSR markers, the statistics of polymorphism information content (PIC), Marker Index (MI) and Effective Multiplex Ratio (EMR) were calculated. Relationships and similarity between Fusarium isolates were analyzed using NTSYS-PC V2.02. Results Out of 96 Fusarium isolates, 48 isolates were identified as Fusarium solani, 25 isolates as Fusarium oxysporum and 23 isolates as Fusarium redolens. A total of 408 bands were obtained from ISSR amplifications. 130 different bands were produced, of which 83 were polymorphic and 47 were monomorphic. The size of PCR fragments produced varied from 273 to 2428 bp. The polymorphism percentage, ranged from the highest (73%) for (ATG)6 to the lowest (56%) for (AG)8C. Primers (ATG)6 and BHB(GA)7 performed better in differentiation Elegans and Martiella-Ventricosum sections from each other. Primers (AG)8C with 26 gene loci, and BHB(GA)7 with 25 gene loci, produced the most bands in Elegans isolates and Martiella-Ventricosum isolates, respectively. Conclusions The results of this research showed that there was a high genetic diversity among the investigated Fusarium isolates and that the ISSR markers are efficient markers to reveal the molecular relationships between Fusarium populations.

Carbon dioxide (CO2) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent, experience-dependent and/or life-stage-dependent behavioural responses to CO2, suggesting that CO2 plays crucial roles throughout the nematode life cycle in multiple ethological contexts. Nematodes also show a wide range of physiological responses to CO2. Here, we review the diverse responses of parasitic and free-living nematodes to CO2. We also discuss the molecular, cellular and neural circuit mechanisms that mediate CO2 detection in nematodes, and that drive context-dependent and experience-dependent responses of nematodes to CO2.

Water is critical for the survival of most cells and organisms. Remarkably, a small number of multicellular animals are able to survive nearly complete drying. The phenomenon of anhydrobiosis, or life without water, has been of interest to researchers for over 300 years. In this review we discuss advances in our understanding of protectants and mechanisms of desiccation tolerance that have emerged from research in three anhydrobiotic invertebrates: brine shrimp (Artemia), roundworms (nematodes), and tardigrades (water bears). Discovery of molecular protectants that allow each of these three animals to survive drying diversifies our understanding of desiccation tolerance, and convergent themes suggest mechanisms that may offer a general model for engineering desiccation tolerance in other contexts.

Chromatin regulators contribute to the maintenance of the germline transcriptional program. In the absence of SET-2, the Caenorhabditis elegans homolog of the SET1/COMPASS H3 Lys4 (H3K4) methyltransferase, animals show transgenerational loss of germline identity, leading to sterility. To identify transcriptional signatures associated with progressive loss of fertility, we performed expression profiling of set-2 mutant germlines across generations. We identify a subset of genes whose misexpression is first observed in early generations, a step we refer to as priming; their misexpression then further progresses in late generations, as animals reach sterility. Analysis of misregulated genes shows that down-regulation of germline genes, expression of somatic transcriptional programs, and desilencing of the X-chromosome are concurrent events leading to loss of germline identity in both early and late generations. Upregulation of transcription factor LIN-15B, the C/EBP homolog CEBP-1, and TGF-β pathway components strongly contribute to loss of fertility, and RNAi inactivation of cebp-1 and TGF-β/Smad signaling delays the onset of sterility, showing they individually contribute to maintenance of germ cell identity. Our approach therefore identifies genes and pathways whose misexpression actively contributes to the loss of germ cell fate. More generally, our data shows how loss of a chromatin regulator in one generation leads to transcriptional changes that are amplified over subsequent generations, ultimately leading to loss of appropriate cell fate.

Objective This research aimed to identify Fusariums belonging to Elegans and Martiella-Ventricosum sections related to cucurbit plants in Tehran province and to evaluate the ability of ISSR markers to investigate the kinship relationships of these groups of Fusariums. Materials and methods In this research, five ISSR primers (AG)8C, (AG)8G, (AC)8YA, (ATG)6 and BHB(GA)7 were selected. Fungal isolates identified based on morphological and microscopic characteristics. For ISSR markers, the statistics of polymorphism information content (PIC), Marker Index (MI) and Effective Multiplex Ratio (EMR) were calculated. Relationships and similarity between Fusarium isolates were analyzed using NTSYS-PC V2.02. Results Out of 96 Fusarium isolates, 48 isolates were identified as Fusarium solani, 25 isolates as Fusarium oxysporum and 23 isolates as Fusarium redolens. A total of 408 bands were obtained from ISSR amplifications. 130 different bands were produced, of which 83 were polymorphic and 47 were monomorphic. The size of PCR fragments produced varied from 273 to 2428 bp. The polymorphism percentage, ranged from the highest (73%) for (ATG)6 to the lowest (56%) for (AG)8C. Primers (ATG)6 and BHB(GA)7 performed better in differentiation Elegans and Martiella-Ventricosum sections from each other. Primers (AG)8C with 26 gene loci, and BHB(GA)7 with 25 gene loci, produced the most bands in Elegans isolates and Martiella-Ventricosum isolates, respectively. Conclusions The results of this research showed that there was a high genetic diversity among the investigated Fusarium isolates and that the ISSR markers are efficient markers to reveal the molecular relationships between Fusarium populations. [ABSTRACT FROM AUTHOR]

cGMP plays a role in sensory signaling and plasticity by regulating ion channels, phosphodiesterases, and kinases. Studies that primarily used genetic and biochemical tools suggest that cGMP is spatiotemporally regulated in multiple sensory modalities. FRET- and GFP-based cGMP sensors were developed to visualize cGMP in primary cell culture and Caenorhabditis elegans to corroborate these findings. While a FRET-based sensor has been used in an intact animal to visualize cGMP, the requirement of a multiple emission system limits its ability to be used on its own as well as with other fluorophores. Here, we demonstrate that a C. elegans codon-optimized version of the cpEGFP-based cGMP sensor FlincG3 can be used to visualize rapidly changing cGMP levels in living, behaving C. elegans We coexpressed FlincG3 with the blue-light-activated guanylyl cyclases BeCyclOp and bPGC in body wall muscles, and found that the rate of change in FlincG3 fluorescence correlated with the rate of cGMP production by each cyclase. Furthermore, we show that FlincG3 responds to cultivation temperature, NaCl concentration changes, and sodium dodecyl sulfate in the sensory neurons AFD, ASEL/R, and PHB, respectively. Intriguingly, FlincG3 fluorescence in ASEL and ASER decreased in response to a NaCl concentration upstep and downstep, respectively, which is opposite in sign to the coexpressed calcium sensor jRGECO1a and previously published calcium recordings. These results illustrate that FlincG3 can be used to report rapidly changing cGMP levels in an intact animal, and that the reporter can potentially reveal unexpected spatiotemporal landscapes of cGMP in response to stimuli.

Stably transmitted transgenes are indispensable for labeling cellular components and manipulating cellular functions. In Caenorhabditis elegans, transgenes are generally generated as inheritable multi-copy extrachromosomal arrays, which can be stabilized in the genome through a mutagenesis-mediated integration process. Standard methods to integrate extrachromosomal arrays primarily use protocols involving ultraviolet light plus trimethylpsoralen or gamma- or X-ray irradiation, which are laborious and time-consuming. Here, we describe a one-step integration method, following germline-mutagenesis induced by mini Singlet Oxygen Generator (miniSOG). Upon blue light treatment, miniSOG tagged to histone (Histone-miniSOG) generates reactive oxygen species (ROS) and induces heritable mutations, including DNA double-stranded breaks. We demonstrate that we can bypass the need to first establish extrachromosomal transgenic lines by coupling microinjection of desired plasmids with blue light illumination on Histone-miniSOG worms to obtain integrants in the F3 progeny. We consistently obtained more than one integrant from 12 injected animals in two weeks. This optogenetic approach significantly reduces the amount of time and labor for transgene integration. Moreover, it enables to generate stably expressed transgenes that cause toxicity in animal growth.

Microsporidia are ubiquitous parasites that infect a wide range of animal hosts, and these fungal-related microbes undergo their entire replicative lifecycle inside of host cells. Despite being widespread in the environment and causing medical and agricultural harm, virtually nothing is known about the host factors important to facilitate their growth and development inside of host cells. Here, we perform a genetic screen to identify host transcription factors important for development of the microsporidian pathogen Nematocida parisii inside intestinal cells of its natural host, the nematode Caenorhabditis elegans Through this screen, we identified the C. elegans Myc family of transcription factors as key host regulators of microsporidia growth and development. The Mad-like transcription factor MDL-1, and the Max-like transcription factors MXL-1 and MXL-2 promote pathogen levels, while the Myc-Mondo-like transcription factor MML-1 inhibits pathogen levels. We used epistasis analysis to show that MDL-1 and MXL-1, which are thought to function as a heterodimer, appear to be acting canonically. In contrast, MXL-2 and MML-1, which are also thought to function as a heterodimer, appear to be acting in separate pathways (noncanonically) in the context of pathogen infection. We also found that both MDL-1::GFP and MML-1::GFP are expressed in intestinal cells during infection. These findings provide novel insight into the host transcription factors that regulate microsporidia development.

Alzheimer’s disease (AD), characterized by memory loss and cognitive decline, is one of the diseases with the highest attrition rate in drug development. As with other neurodegenerative diseases, AD manifests on several scales (molecular, cellular and organismal), resulting in an organismal phenotype that is difficult to replicate and exploit for screening in vitro. Development of high-throughput drug screening platforms using invertebrate organisms may therefore facilitate drug discovery in AD, at least for compounds that target mechanisms that can be modelled in invertebrates, such as metabolic defects and mitochondrial toxicity. Here we present a potentially high-throughput screening platform against AD in Caenorhabditis elegans (C. elegans). The system is based on our transgenic AD model strain (GRU102) that expresses a pathogenic human amyloid-beta peptide (Aβ1-42) specifically in neurons and we use this approach to identify Metformin, Lithium and Curcumin as potential “hits”. We find that the ability to rescue the swim-exhaustion phenotype correlates well with lifespan and healthspan improvements in GRU102. Importantly, several other drugs, such as Thioflavin T that have been reported previously to extend lifespan, modify aspects of ageing or for which protective effects in AD model might be suspected did not rescue the swim performance nor lifespan of GRU102. This illustrates the predictive value of the screening assay and confirms that not all compounds targeting ageing are capable of compensating for the toxic effects of Aβ1-42 in GRU102. Together, these findings demonstrate the utility of our screen towards the Aβ-induced defects in GRU102.

Introdução: Dietas ricas em açúcares podem promover um distúrbio do metabolismo e gerar consequências negativas, afetando inclusive o sistema nervoso e o controle das respostas imunes frente a patógenos. Estudos recentes demonstraram que o sistema dopaminérgico pode atuar como um regulador do sistema imune. Em Caenorhabditis elegans, cepas marcadas com proteína G fluorescente (GFP) permitem a visualização de circuitos neuronais dopaminérgicos, possibilitando a visualização de danos nos mesmos. Além disso, esses animais são infectados por patógenos humanos como Pseudomonas aeruginosa e Staphylococcus aureus. Objetivo: Investigar se dietas com altas concentrações de glicose podem afetar a fisiologia de C. elegans, e consequentemente, impactar na sobrevivência dos vermes a infecções bacterianas. Método: 2% de glicose foi adicionada ao meio usual para nematoides (NGM) e fornecida para os vermes (cerca de 1500 animais) durante os estágios de desenvolvimento L1 a L4. Como controle foram utilizados animais com a dieta usual em meio NGM. A fisiologia dos animais foi verificada através dos ensaios de batimento faríngeo, tamanho corporal, defecação e reprodução utilizando a cepa selvagem N2. Essa cepa também foi utilizada para o ensaio de sobrevivência (infecção) com as bactérias P. aeruginosa e S. aureus. Este foi realizado em meio líquido, em placas de 96 poços contendo tampão M9 e colesterol. As placas foram incubadas a 25°C e a sobrevivência dos animais foi verificada a cada 24 horas. A análise de dano neuronal dopaminérgico (presença ou ausência de danos) foi realizada com a cepa BY200 (marcada com GFP). Resultados: Vermes alimentados com glicose não apresentaram alteração nos batimentos faríngeos em relação ao controle com a dieta usual. Entretanto, esses animais apresentaram uma diminuição no tempo de seu ciclo de defecação, na capacidade de gerar progênie, e também um aumento no comprimento corporal. Na avaliação de danos nos neurônios dopaminérgicos, houve um aumento no percentual de animais que apresentaram algum tipo de dano neuronal quando alimentados com 2% de glicose (56,89%) em relação ao controle com dieta usual (37,14%; diferença estatisticamente significativa). Animais alimentados com altas concentrações de glicose tiveram um aumento na sobrevivência a infecções por P. aeruginosa e S. aureus em relação ao controle com a dieta usual (medianas de 7 e 6 dias, respectivamente). Conclusão: Altas concentrações de glicose afetam parâmetros fisiológicos dos vermes como tamanho corporal, reprodução e ciclo de defecação, além de provocar um aumento de danos neuronais no sistema dopaminérgico. Porém, ao contrário do esperado, apesar dos danos causados pela dieta, animais alimentados com altas concentrações de glicose não tiveram um desfecho negativo quando infectados pelas bactérias P. aeruginosa e S. aureus. Nas condições avaliadas, a dieta com altas concentrações de glicose teve efeito positivo, permitindo um aumento na sobrevivência dos animais as infecções por P. aeruginosa e S. aureus. [ABSTRACT FROM AUTHOR]

Chromatin regulators contribute to the maintenance of the germline transcriptional program. In the absence of SET-2, the Caenorhabditis elegans homolog of the SET1/COMPASS H3 Lys4 (H3K4) methyltransferase, animals show transgenerational loss of germline identity, leading to sterility. To identify transcriptional signatures associated with progressive loss of fertility, we performed expression profiling of set-2 mutant germlines across generations. We identify a subset of genes whose misexpression is first observed in early generations, a step we refer to as priming; their misexpression then further progresses in late generations, as animals reach sterility. Analysis of misregulated genes shows that down-regulation of germline genes, expression of somatic transcriptional programs, and desilencing of the X-chromosome are concurrent events leading to loss of germline identity in both early and late generations. Upregulation of transcription factor LIN-15B, the C/EBP homolog CEBP-1, and TGF-β pathway components strongly contribute to loss of fertility, and RNAi inactivation of cebp-1 and TGF-β/Smad signaling delays the onset of sterility, showing they individually contribute to maintenance of germ cell identity. Our approach therefore identifies genes and pathways whose misexpression actively contributes to the loss of germ cell fate. More generally, our data shows how loss of a chromatin regulator in one generation leads to transcriptional changes that are amplified over subsequent generations, ultimately leading to loss of appropriate cell fate.

John Sulston changed the way we do science, not once, but three times – initially with the complete cell lineage of the nematode Caenorhabditis elegans, next with completion of the genome sequences of the worm and human genomes and finally with his strong and active advocacy for open data sharing. His contributions were widely recognized and in 2002 he received the Nobel Prize in Physiology and Medicine. [ABSTRACT FROM AUTHOR]

Calcium homeostasis modulators (CALHMs/CLHMs) comprise a family of pore‐forming protein complexes assembling into voltage‐gated, Ca2+‐sensitive, nonselective channels. These complexes contain an ion‐conduction pore sufficiently wide to permit the passing of ATP molecules serving as neurotransmitters. While their function and structure information is accumulating, the precise mechanisms of these channel complexes remain to be full understood. Here, we present the structure of the Caenorhabditis elegans CLHM1 channel in its open state solved through single‐particle cryo‐electron microscopy at 3.7‐Å resolution. The transmembrane region of the channel structure of the dominant class shows an assembly of 10‐fold rotational symmetry in one layer, and its cytoplasmic region is involved in additional twofold symmetrical packing in a tail‐to‐tail manner. Furthermore, we identified a series of amino acid residues critical for the regulation of CeCLHM1 channel using functional assays, electrophysiological analyses as well as structural‐based analysis. Our structure and function analyses provide new insights into the mechanisms of CALHM channels. [ABSTRACT FROM AUTHOR]

Long-term survival of an animal species depends on development being robust to environmental variations and climate changes. We used C. elegans to study how mechanisms that sense environmental changes trigger adaptive responses that ensure animals develop properly. In water, the nervous system induces an adaptive response that reinforces vulval development through an unknown backup signal for vulval induction. This response involves the heterotrimeric G-protein EGL-30//Gαq acting in motor neurons. It also requires bodywall muscle, which is excited by EGL-30-stimulated synaptic transmission, suggesting a behavioral function of neurons induces backup signal production from muscle. We now report that increased acetylcholine during liquid growth activates an EGL-30-Rho pathway, distinct from the synaptic transmission pathway, that increases Wnt production from motor neurons. We also provide evidence that this neuronal Wnt contributes to EGL-30-stimulated vulval development, with muscle producing a parallel developmental signal. As diverse sensory modalities stimulate motor neurons via acetylcholine, this mechanism enables broad sensory perception to enhance Wntdependent development. Thus, sensory perception improves animal fitness by activating distinct neuronal functions that trigger adaptive changes in both behavior and developmental processes. [ABSTRACT FROM AUTHOR]

UDP- glucose: glycoprotein glucosyltransferase (UGGT) is a protein that operates as the gatekeeper for the endoplasmic reticulum (ER) quality control mechanism of glycoprotein folding. It is known that vertebrates and Caenorhabditis genomes harbor two uggt gene copies that exhibit differences in their properties. Bayesian phylogenetic inference based on 195 UGGT and UGGT-like protein sequences of an ample spectrum of eukaryotic species showed that uggt genes went through independent duplications in Caenorhabditis and vertebrates. In both lineages, the catalytic domain of the duplicated genes was subjected to a strong purifying selective pressure, while the recognition domain was subjected to episodic positive diversifying selection. Selective relaxation in the recognition domain was more pronounced in Caenorhabditis uggt-b than in vertebrates uggt-2. Structural bioinformatics analysis revealed that Caenorhabditis UGGT-b protein lacks essential sequences proposed to be involved in the recognition of unfolded proteins. When we assayed glucosyltrasferase activity of a chimeric protein composed by Caenorhabditis uggt-b recognition domain fused to S. pombe catalytic domain expressed in yeast, no activity was detected. The present results support the conservation of the UGGT activity in the catalytic domain and a putative divergent function of the recognition domain for the UGGT2 protein in vertebrates, which would have gone through a specialization process. In Caenorhabditis, uggt-b evolved under different constraints compared to uggt-a which, by means of a putative neofunctionalization process, resulted in a non-redundant paralog. The non-canonical function of uggt-b in the worm lineage highlights the need to take precautions before generalizing gene functions in model organisms. [ABSTRACT FROM AUTHOR]

Vitellogenins are a family of yolk proteins that are by far the most abundant among oviparous animals. In the model nematode Caenorhabditis elegans, the 6 vitellogenins are among the most highly expressed genes in the adult hermaphrodite intestine, which produces copious yolk to provision eggs. In this article we review what is known about the vitellogenin genes and proteins in C. elegans, in comparison with vitellogenins in other taxa. We argue that the primary purpose of abundant vitellogenesis in C. elegans is to support post-embryonic development and fertility, rather than embryogenesis, especially in harsh environments. Increasing vitellogenin provisioning underlies several post-embryonic phenotypic alterations associated with advancing maternal age, demonstrating that vitellogenins can act as an intergenerational signal mediating the influence of parental physiology on progeny. We also review what is known about vitellogenin regulation – how tissue-, sex- and stage-specificity of expression is achieved, how vitellogenins are regulated by major signaling pathways, how vitellogenin expression is affected by extra-intestinal tissues and how environmental experience affects vitellogenesis. Lastly, we speculate whether C. elegans vitellogenins may play other roles in worm physiology.

PUF (PUmilio/FBF) RNA-binding proteins recognize distinct elements. In C. elegans, PUF-8 binds to an 8-nt motif and restricts proliferation in the germline. Conversely, FBF-2 recognizes a 9-nt element and promotes mitosis. To understand how motif divergence relates to biological function, we first determined a crystal structure of PUF-8. Comparison of this structure to that of FBF-2 revealed a major difference in a central repeat. We devised a modified yeast 3-hybrid screen to identify mutations that confer recognition of an 8-nt element to FBF-2. We identified several such mutants and validated structurally and biochemically their binding to 8-nt RNA elements. Using genome engineering, we generated a mutant animal with a substitution in FBF-2 that confers preferential binding to the PUF-8 element. The mutant largely rescued overproliferation in animals that spontaneously generate tumors in the absence of puf-8. This work highlights the critical role of motif length in the specification of biological function.

Vitellogenins are a family of yolk proteins that are by far the most abundant among oviparous animals. In the model nematode Caenorhabditis elegans , the 6 vitellogenins are among the most highly expressed genes in the adult hermaphrodite intestine, which produces copious yolk to provision eggs. In this article we review what is known about the vitellogenin genes and proteins in C. elegans , in comparison with vitellogenins in other taxa. We argue that the primary purpose of abundant vitellogenesis in C. elegans is to support post-embryonic development and fertility, rather than embryogenesis, especially in harsh environments. Increasing vitellogenin provisioning underlies several post-embryonic phenotypic alterations associated with advancing maternal age, demonstrating that vitellogenins can act as an intergenerational signal mediating the influence of parental physiology on progeny. We also review what is known about vitellogenin regulation – how tissue-, sex- and stage-specificity of expression is achieved, how vitellogenins are regulated by major signaling pathways, how vitellogenin expression is affected by extra-intestinal tissues and how environmental experience affects vitellogenesis. Lastly, we speculate whether C. elegans vitellogenins may play other roles in worm physiology. [ABSTRACT FROM AUTHOR]

In this study we provide a simplified model of the forward oscillatory locomotion neural circuit of the worm C. Elegans. Based on available connectome but lacking electrophysiological data on neurons and synapses we fill this gap by fine-tuning the electrophysiological parameters of the model so that it achieves oscillations. We observe that without electrical synapses the motor neurons are not active synchronously, thus hindering movement patterns observed in live worms. After the introduction of electrical synapses into the model, motor neurons work in synchrony. Worm C. Elegans is still the only organism with a completely mapped connectome. This makes it a popular system for computational modelling. C. Elegans hermaphrodite has 302 neurons. The number of chemical and electrical synapses is in the thousands but is not yet definitively mapped. A seminal study by White et al.(1986) provided the first description of C. Elegans connectome and is continually updated. In spite of its relatively simple nervous system, C. Elegans is capable of a whole range of behaviours. The locomotory system of C. Elegans comprises of 95 wall muscles and 75 ventral cord motor neurons. Motor neurons are regulated by motor command interneurons. A worm moves by propagating bends along its body. C. Elegans is capable of moving forward and backward with differing speed. It can also realise U-turns to abruptly change the direction of its movement. Using Animatlab2 software we specified a set of neurons. We built two pairs of artificial motor neurons, representing VB and DB class and a single artificial neuron representing the PVC interneuron. Parameters of neurons and synapses were set by the software and fine-tuned by the authors to mimic processes described in theory. The first step was to build an oscillatory circuit that would enable the undulatory movement of the animal. We set up the PVC neuron with 100 nA tonic stimulus that would simulate incoming impulses that drive the forward movement. We also added 0.1 mV tonic noise to all neurons simulating noise inherent in neural systems. The initial threshold of the PVC neuron was -40mV; the resting potential was -60mV. Accommodation time constant was set to 10 ms, AHP conductance to 1 microS and AHP time constant to 3 ms. Relative accommodation was set to 0.3, relative size to 1 and time constant to 5 ms. We then set up DB1, DB2, VB1 and VB2 neurons with the same parameters: the initial threshold of neurons was -40mV, and the resting potential was -60mV. The accommodation time constant was set to 1 ms, the AHP conductance to 1 microS and the AHP time constant to 30 ms. The relative accommodation was set to 0.3, the relative size to 1 and the time constant to 5 ms. In the next step we introduced four depolarising IPSP synapses from PVC to DB and VB neurons. The equilibrium potential of each synapse was set to -30 mV, the decay rate to 10 ms and the facilitation decay to 100 ms. The relative facilitation was set to 1 and the synaptic conductance to 5 microS. Then we built two pairs of mutually inhibitory synapses; between DB1 and VB1 and between DB2 and VB2. These reciprocal inhibitory synapses together with the threshold adaptation enable oscillation of activity alternating between DB and VB neurons. The parameters of inhibitory (hyperpolarising IPSP synapses) were set as follows: the equilibrium potential of each synapse was set to -70 mV, the decay rate to 10 ms and the facilitation decay to 100 ms. The relative facilitation was set to 1.5 and the synaptic conductance to 0.5 microS. There are more ways to achieve oscillation in a neural circuit. We do not know yet what mechanism is used in C. Elegans as we have very little information on the electrophysiology of C. Elegans neurons. Oscillation can happen because of a rhythmically bursting pacemaker neuron or by mutual inhibition of neurons with adaptation of either neural threshold or the synapses. In our study we provide a possible mechanism of oscillatory synchronised activity necessary for C. Elegans locomotion. We show that without the electrical synapses muscle, contraction would not be synchronous and forward movement would not happen. [ABSTRACT FROM AUTHOR]

Propionic acidemia (PA) is a classical inborn error of metabolism with high morbidity that results from the inability of the propionyl-CoA carboxylase (PCC) enzyme to convert propionyl-CoA to methylmalonyl-CoA. PA is inherited in an autosomal recessive fashion due to functional loss of both alleles of either PCCA or PCCB. These genes are highly conserved across evolutionarily diverse species and share extensive similarity with pcca-1 and pccb-1 in the nematode, Caenorhabditis elegans. Here, we report the global metabolic effects of deletion in a single PCC gene, either pcca-1 or pccb- 1, in C. elegans. Animal lifespan was significantly reduced relative to wild-type worms in both mutant strains, althoughto a greater degree in pcca-1. Mitochondrial oxidative phosphorylation (OXPHOS) capacity and efficiency as determined by direct polarography of isolated mitochondria were also significantly reduced in both mutant strains. While in vivo quantitation of mitochondrial physiology was normal in pccb-1 mutants, pcca-1 deletion mutants had significantly increased mitochondrial matrix oxidant burden as well as significantly decreased mitochondrial membrane potential and mitochondrial content. Whole worm steady-state free amino acid profiling by UPLC revealed reduced levels in both mutant strains of the glutathione precursor cysteine, possibly suggestive of increased oxidative stress. Intermediary metabolic flux analysis by GC/ MS with 1,6-13C2-glucose further showed both PCC deletion strains had decreased accumulation of a distal tricarboxylic acid (TCA) cycle metabolic intermediate (+1 malate), isotopic enrichment in a proximal TCA cycle intermediate (+1 citrate), and increased +1 lactate accumulation. GC/MS analysis further revealed accumulation in the PCC mutants of a small amount of 3-hydroxypropionate, which appeared to be metabolized in C. elegans to oxalate through a unique metabolic pathway. Collectively, these detailed metabolic investigations in translational PA model animals with genetic-based PCC deficiency reveal their significantly dysregulated energy metabolism at multiple levels, including reduced mitochondrial OXPHOS capacity, increased oxidative stress, and inhibition of distal TCA cycle flux, culminating in reduced animal lifespan. These findings demonstrate that the pathophysiology of PA extends well beyond what has classically been understood as a single PCC enzyme deficiency with toxic precursor accumulation, and suggest that therapeutically targeting the globally disrupted energy metabolism may offer novel treatment opportunities for PA. Summary: Two C. elegans model animals of propionic acidemia with single-gene pcca-1 or pccb- 1 deletions have reduced lifespan with significantly reduced mitochondrial energy metabolism and increased oxidative stress, reflecting the disease's broader pathophysiology beyond a single enzyme deficiency with toxic precursor accumulation. [ABSTRACT FROM AUTHOR]

Caenorhabditis elegans are typically cultured in a monoxenic medium consisting of live bacteria. However, this introduces a secondary organism to experiments, and restricts the manipulation of the nutritional environment. Due to the intricate link between genes and environment, greater control and understanding of nutritional factors are required to push the C. elegans field into new areas. For decades, attempts to develop a chemically defined, axenic medium as an alternative for culturing C. elegans have been made. However, the mechanism by which the filter feeder C. elegans obtains nutrients from these liquid media is not known. Using a fluorescence-activated cell sorting based approach, we demonstrate growth in all past axenic C. elegans media to be dependent on the presence of previously unknown particles. This particle requirement of C. elegans led to development of liposome-based, nanoparticle culturing that allows full control of nutrients delivered to C. elegans. [ABSTRACT FROM AUTHOR]

Metabolic homeostasis is coordinately controlled by diverse inputs. Understanding these regulatory networks is vital to combating metabolic disorders. The nematode Caenorhabditis elegans has emerged as a powerful, genetically tractable model system for the discovery of lipid regulatory mechanisms. Here we introduce DBL-1, the C. elegans homolog of bone morphogenetic protein 2/4 (BMP2/4), as a significant regulator of lipid homeostasis. We used neutral lipid staining and a lipid droplet marker to demonstrate that both increases and decreases in DBL-1/BMP signaling result in reduced lipid stores and lipid droplet count. We find that lipid droplet size, however, correlates positively with the level of DBL-1/ BMP signaling. Regulation of lipid accumulation in the intestine occurs through non-cell-autonomous signaling, since expression of SMA-3, a Smad signal transducer, in the epidermis (hypodermis) is sufficient to rescue the loss of lipid accumulation. Finally, genetic evidence indicates that DBL-1/BMP functions upstream of Insulin/IGF-1 Signaling in lipid metabolism. We conclude that BMP signaling regulates lipid metabolism in C. elegans through interorgan signaling to the Insulin pathway, shedding light on a less well-studied regulatory mechanism for metabolic homeostasis. [ABSTRACT FROM AUTHOR]