scholarly journals SPE-51, a sperm secreted protein with an Immunoglobulin-like domain, is required for sperm-egg fusion in C. elegans

2021 ◽  
Author(s):  
Xue Mei ◽  
Marina Druzhinina ◽  
Sunny Dharia ◽  
Amber R. Krauchunas ◽  
Julie Ni ◽  
...  
Keyword(s):  
Amino Acids ◽  
Caenorhabditis Elegans ◽  
Molecular Basis ◽  
Reproductive Tract ◽  
Forward Genetics ◽  
Secreted Proteins ◽  
Secreted Protein ◽  
Specific Function ◽  
C Elegans ◽  
Sperm Surface

Despite the importance of fertilization, the molecular basis of sperm-egg interaction is not well understood. In a forward genetics screen for fertility mutants in Caenorhabditis elegans we identified spe-51. Mutant worms make sperm that are unable to fertilize the oocyte but otherwise normal by all available measurements. The spe-51 gene encodes a secreted protein that includes an immunoglobulin (Ig)-like domain and a hydrophobic sequence of amino acids. The SPE-51 protein acts cell-autonomously and localizes to the surface of the spermatozoa. This is the first example of a secreted protein required for the interactions between the sperm and egg with genetic validation for a specific function in fertilization. Our analyses of these genes begin to build a paradigm for sperm-secreted or reproductive tract-secreted proteins that coat the sperm surface and influence their survival, motility, and/or the ability to fertilize the egg.

Behavioral Effects of Volatile Anesthetics in Caenorhabditis elegans

1996 ◽  
Vol 85 (4) ◽  
pp. 901-912 ◽  
Author(s):  
Michael C. Crowder ◽  
Laynie D. Shebester ◽  
Tim Schedl
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Time Course ◽  
Model Organism ◽  
Volatile Anesthetic ◽  
Volatile Anesthetics ◽  
Effective Concentration ◽  
Forward Genetics ◽  
C Elegans ◽  
Median Effective Concentration

Background The nematode Caenorhabditis elegans offers many advantages as a model organism for studying volatile anesthetic actions. It has a simple, well-understood nervous system; it allows the researcher to do forward genetics; and its genome will soon be completely sequenced. C. elegans is immobilized by volatile anesthetics only at high concentrations and with an unusually slow time course. Here other behavioral dysfunctions are considered as anesthetic endpoints in C. elegans. Methods The potency of halothane for disrupting eight different behaviors was determined by logistic regression of concentration and response data. Other volatile anesthetics were also tested for some behaviors. Established protocols were used for behavioral endpoints that, except for pharyngeal pumping, were set as complete disruption of the behavior. Time courses were measured for rapid behaviors. Recovery from exposure to 1 or 4 vol% halothane was determined for mating, chemotaxis, and gross movement. All experiments were performed at 20 to 22 degrees C. Results The median effective concentration values for halothane inhibition of mating (0.30 vol%-0.21 mM), chemotaxis (0.34 vol%-0.24 mM), and coordinated movement (0.32 vol% - 0.23 mM) were similar to the human minimum alveolar concentration (MAC; 0.21 mM). In contrast, halothane produced immobility with a median effective concentration of 3.65 vol% (2.6 mM). Other behaviors had intermediate sensitivities. Halothane's effects reached steady-state in 10 min for all behaviors tested except immobility, which required 2 h. Recovery was complete after exposure to 1 vol% halothane but was significantly reduced after exposure to immobilizing concentrations. Conclusions Volatile anesthetics selectively disrupt C. elegans behavior. The potency, time course, and recovery characteristics of halothane's effects on three behaviors are similar to its anesthetic properties in vertebrates. The affected nervous system molecules may express structural motifs similar to those on vertebrate anesthetic targets.

scholarly journals Molecular basis of synaptic vesicle cargo recognition by the endocytic sorting adaptor stonin 2

2007 ◽  
Vol 179 (7) ◽  
pp. 1497-1510 ◽  
Author(s):  
Nadja Jung ◽  
Martin Wienisch ◽  
Mingyu Gu ◽  
James B. Rand ◽  
Sebastian L. Müller ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Synaptic Vesicles ◽  
Molecular Basis ◽  
C Elegans ◽  
Evolutionarily Conserved ◽  
Molecular Determinants ◽  
Direct Association ◽  
Endocytic Sorting ◽  
Synaptotagmin 1 ◽  
Stonin 2

Synaptic transmission depends on clathrin-mediated recycling of synaptic vesicles (SVs). How select SV proteins are targeted for internalization has remained elusive. Stonins are evolutionarily conserved adaptors dedicated to endocytic sorting of the SV protein synaptotagmin. Our data identify the molecular determinants for recognition of synaptotagmin by stonin 2 or its Caenorhabditis elegans orthologue UNC-41B. The interaction involves the direct association of clusters of basic residues on the surface of the cytoplasmic domain of synaptotagmin 1 and a β strand within the μ–homology domain of stonin 2. Mutation of K783, Y784, and E785 to alanine within this stonin 2 β strand results in failure of the mutant stonin protein to associate with synaptotagmin, to accumulate at synapses, and to facilitate synaptotagmin internalization. Synaptotagmin-binding–defective UNC-41B is unable to rescue paralysis in C. elegans stonin mutant animals, suggesting that the mechanism of stonin-mediated SV cargo recognition is conserved from worms to mammals.

scholarly journals Mutation of a putative sperm membrane protein in Caenorhabditis elegans prevents sperm differentiation but not its associated meiotic divisions.

1992 ◽  
Vol 119 (1) ◽  
pp. 55-68 ◽  
Author(s):  
S W L'Hernault ◽  
P M Arduengo
Keyword(s):  
Caenorhabditis Elegans ◽  
Membrane Protein ◽  
Molecular Basis ◽  
Close Association ◽  
Integral Membrane Protein ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Fibrous Body ◽  
Sperm Membrane ◽  
Internal Membrane Structure

Spermatogenesis in the nematode Caenorhabditis elegans uses unusual organelles, called the fibrous body-membranous organelle (FB-MO) complexes, to prepackage and deliver macromolecules to spermatids during cytokinesis that accompanies the second meiotic division. Mutations in the spe-4 (spermatogenesis-defective) gene disrupt these organelles and prevent cytokinesis during spermatogenesis, but do not prevent completion of the meiotic nuclear divisions that normally accompany spermatid formation. We report an ultrastructural analysis of spe-4 mutant sperm where the normally close association of the FB's with the MO's and the double layered membrane surrounding the FB's are both defective. The internal membrane structure of the MO's is also disrupted in spe-4 mutant sperm. Although sperm morphogenesis in spe-4 mutants arrests prior to the formation of spermatids, meiosis can apparently be completed so that haploid nuclei reside in an arrested spermatocyte. We have cloned the spe-4 gene in order to understand its role during spermatogenesis and the molecular basis of how mutation of this gene disrupts this process. The spe-4 gene encodes an approximately 1.5-kb mRNA that is expressed during spermatogenesis, and the sequence of this gene suggests that it encodes an integral membrane protein. These data suggest that mutation of an integral membrane protein within FB-MO complexes disrupts morphogenesis and prevents formation of spermatids but does not affect completion of the meiotic nuclear divisions in C. elegans sperm.

Optimal levels of the essential amino acids histidine, lysine and threonine in Caenorhabditis elegans maintenance medium

Nematology ◽  
2008 ◽  
Vol 10 (4) ◽  
pp. 539-544 ◽  
Author(s):  
Nancy Lu ◽  
Xiaoyan Xiong
Keyword(s):  
Amino Acids ◽  
Caenorhabditis Elegans ◽  
Population Growth ◽  
Dry Weight ◽  
Essential Amino Acids ◽  
Maintenance Medium ◽  
C Elegans ◽  
Quantitative Studies ◽  
Free Living Nematode ◽  
Optimal Population

AbstractCurrent Caenorhabditis elegans Maintenance Medium (C-CeMM) is used to cultivate the free-living nematode, C. elegans. In C-CeMM, ten amino acids (AA) were found to be nutritionally essential. The optimal requirements of seven of these ten essential AA were determined previously. The objectives of the present study were to determine the optimal requirements of the remaining three essential AA: histidine, lysine and threonine. The Optimal Caenorhabditis elegans Maintenance Medium (O-CeMM) was formulated using the levels of all essential AA that supported the optimal population growth for C. elegans from previous quantitative studies and from the results obtained in the first part of this study. The efficacy of O-CeMM, C-CeMM, as well as Egg CeMM (E-CeMM), based on the essential AA ratio in hen's egg, was studied. The optimal requirements (mg ml–1) of histidine, lysine and threonine were determined to be 2.26 (8× C-CeMM), 1.03-2.06 (1× to 2× C-CeMM), and 0.717-2.86 (1× to 4× C-CeMM), respectively. It was found that O-CeMM supported a significantly higher (1.55 ∼ 1.60×) population growth (number of nematodes/ml) when compared with C-CeMM and E-CeMM. For both O-CeMM and C-CeMM, the AA efficiency ratio (AAER; g dry weight (wt) gain of C. elegans/g of total AA) was determined to be 0.18, which was significantly higher than the 0.15 that was determined in E-CeMM. Although the O-CeMM supported a significantly higher population growth, a higher level of histidine and consequently higher total AA were used in O-CeMM than in C-CeMM. Therefore, based on the findings on AAER, it was concluded that both the O-CeMM and C-CeMM were equally efficient for the cultivation of C. elegans.

scholarly journals A lineage-resolved molecular atlas of C. elegans embryogenesis at single-cell resolution

Science ◽  
2019 ◽  
Vol 365 (6459) ◽  
pp. eaax1971 ◽  
Author(s):  
Jonathan S. Packer ◽  
Qin Zhu ◽  
Chau Huynh ◽  
Priya Sivaramakrishnan ◽  
Elicia Preston ◽  
...  
Keyword(s):  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Single Cell ◽  
Molecular Basis ◽  
Cell Types ◽  
Embryonic Cells ◽  
Cell Type ◽  
C Elegans ◽  
Exact Position ◽  
Sister Cells

Caenorhabditis elegans is an animal with few cells but a wide diversity of cell types. In this study, we characterize the molecular basis for their specification by profiling the transcriptomes of 86,024 single embryonic cells. We identify 502 terminal and preterminal cell types, mapping most single-cell transcriptomes to their exact position in C. elegans’ invariant lineage. Using these annotations, we find that (i) the correlation between a cell’s lineage and its transcriptome increases from middle to late gastrulation, then falls substantially as cells in the nervous system and pharynx adopt their terminal fates; (ii) multilineage priming contributes to the differentiation of sister cells at dozens of lineage branches; and (iii) most distinct lineages that produce the same anatomical cell type converge to a homogenous transcriptomic state.

scholarly journals Glycine promotes longevity in Caenorhabditis elegans in a methionine cycle-dependent fashion

2018 ◽  
Author(s):  
Yasmine J. Liu ◽  
Georges E. Janssens ◽  
Rashmi Kamble ◽  
Arwen W. Gao ◽  
Aldo Jongejan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Amino Acid ◽  
Caenorhabditis Elegans ◽  
C Elegans ◽  
Beneficial Effects ◽  
A Genome ◽  
Methionine Cycle ◽  
Cycle Dependent

AbstractThe deregulation of metabolism is a hallmark of aging. As such, changes in the expression of metabolic genes and the profiles of amino acid levels are features associated with aging animals. We previously reported that the levels of most amino acids decline with age in Caenorhabditis elegans (C. elegans). Glycine, in contrast, substantially accumulates in aging C. elegans. In this study we show that this is coupled to a decrease in gene expression of enzymes important for glycine catabolism. We further show that supplementation of glycine significantly prolongs C. elegans lifespan and ameliorates specific transcriptional changes that are associated with aging. Glycine feeds into the methionine cycle. We find that mutations in components of this cycle, methionine synthase (metr-1) and S-adenosylmethionine synthetase (sams-1), completely abrogate glycine-induced lifespan extension. Strikingly, the beneficial effects of glycine supplementation are conserved when we supplement with serine, also driving the methionine cycle. RNA sequencing of serine- and glycine-supplemented worms reveals similar transcriptional profiles including widespread gene suppression. Taken together, these data uncover a novel role of glycine in the deceleration of aging through its function in the methionine cycle.Author summaryThere are a growing number of studies showing that amino acids function as signal metabolites that influence aging and health. Although contemporary -OMICs studies have uncovered various associations between metabolite levels and aging, in many cases the directionality of the relationships is unclear. In a recent metabolomics study, we found that glycine accumulates in aged C. elegans while other amino acids decrease. The present study shows that glycine supplementation prolongs longevity and drives a genome-wide inhibition effect on C. elegans gene expression. Glycine as a one-carbon donor fuels the methyl pool of one-carbon metabolism composed of folates and methionine cycle. We find that glycine-mediated longevity effect is fully dependent on methionine cycle, and that all of these observations are conserved with supplementation of the other one-carbon amino acid, serine. These results provide a novel role for glycine as a promoter of longevity and bring new insight into the role of one-carbon amino acids in the regulation of aging that may ultimately be beneficial for humans.

scholarly journals The uptake of avermectins in Caenorhabditis elegans is dependent on Intra-Flagellar Transport and other protein trafficking pathways

2021 ◽  
Author(s):  
Robert A Brinzer ◽  
David J France ◽  
Claire McMaster ◽  
Stuart Ruddell ◽  
Alan D Winter ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Protein Trafficking ◽  
Molecular Mechanisms ◽  
Intraflagellar Transport ◽  
Resistance Mechanisms ◽  
Forward Genetics ◽  
Cross Resistance ◽  
Parasitic Nematodes ◽  
C Elegans ◽  
Downstream Effectors

Parasitic nematodes are globally important and place a heavy disease burden on infected humans, crops and livestock, while commonly administered anthelmintics used for treatment are being rendered ineffective by increasing levels of resistance. Although the modes of action and resistance mechanisms caused by detoxification and target site insensitivity for these compounds is well documented, the mechanisms for uptake, which can also cause resistance, are still poorly defined. It has recently been shown in the model nematode Caenorhabditis elegans that the avermectins or macrocyclic lactones such as ivermectin and moxidectin gain entry though the sensory cilia of the amphid neurons. This study interrogated the molecular mechanisms involved in the uptake of avermectins using a combination of forward genetics and targeted resistance screening approaches along with visualising a BODIPY labelled ivermectin analog and confirmed the importance of intraflagellar transport in this process. This approach also identified the protein trafficking pathways used by the downstream effectors and the components of the ciliary basal body that are required for effector entry into these non-motile structures. Mutations in many of the genes under investigation also resulted in resistance to the unrelated anthelmintic drugs albendazole and levamisole, giving insights into the potential mechanisms of multidrug resistance observed in field isolates of the parasitic nematodes that are a scourge of ruminant livestock. In total 50 novel C. elegans anthelmintic survival associated genes were identified in this study, three of which (daf-6, rab-35 and inx-19) are associated with broad spectrum cross resistance. When combined with previously known resistance genes, there are now 53 resistance associated genes which are directly involved in amphid, cilia and IFT function.

scholarly journals Distinct mechanoreceptor pezo-1 isoforms modulate food intake in the nematode Caenorhabditis elegans

2021 ◽  
Author(s):  
Kiley J Hughes ◽  
Ashka Shah ◽  
Xiaofei Bai ◽  
Jessica Adams ◽  
Rosemary Bauer ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Basis ◽  
Digestive System ◽  
Cation Channels ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Functional Differences ◽  
Pharyngeal Muscles ◽  
Differential Pattern ◽  
Sensory Processes

Two PIEZO mechanosensitive cation channels, PIEZO1 and PIEZO2, have been identified in mammals, where they are involved in numerous sensory processes. While structurally similar, PIEZO channels are expressed in distinct tissues and exhibit unique properties. How different PIEZOs transduce force, how their transduction mechanism varies, and how their unique properties match the functional needs of the distinct tissues where they are expressed remain all-important unanswered questions. The nematode Caenorhabditis elegans has a single PIEZO ortholog (pezo-1) predicted to have twelve isoforms. These isoforms share many transmembrane domains, but differ in those that distinguish PIEZO1 and PIEZO2 in mammals. Here we use translational and transcriptional reporters to show that long pezo-1 isoforms are selectively expressed in mesodermally derived tissues (such as muscle and glands). In contrast, shorter pezo-1 isoforms are primarily expressed in neurons. In the digestive system, different pezo-1 isoforms appear to be expressed in different cells of the same organ. We show that pharyngeal muscles, glands, and valve rely on long pezo-1 isoforms to respond appropriately to the presence of food. The unique pattern of complementary expression of pezo-1 isoforms suggest that different isoforms possess distinct functions. The number of pezo-1 isoforms in C. elegans, their differential pattern of expression, and their roles in experimentally tractable processes make this an attractive system to investigate the molecular basis for functional differences between members of the PIEZO family of mechanoreceptors.

scholarly journals ENU-3 is a novel outgrowth and guidance protein in c. elegans

2021 ◽  
Author(s):  
Callista Stephanie Yee
Keyword(s):  
Amino Acids ◽  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Membrane Protein ◽  
Motor Neuron ◽  
Gene Product ◽  
Motor Neurons ◽  
Growth Cones ◽  
C Elegans ◽  
Extracellular Molecules

During the development of the nervous system, the migration of many cells and axons is guided by extracellular molecules. These molecules bind to receptors at the tips of the growth cones of migrating axons and trigger intracellular signalling to steer the axons along the correct trajectories. Previous work has identified a novel mutant, enu-3 (enhancer of Unc), that enhances the motor neuron axon outgrowth defects observed in strains of Caenorhabditis elegans that lack either the UNC-5 receptor or its ligand UNC-6/Netrin, enu-3 single mutants have weak motor neuron axon migration defects. Both outgrowth defects of double mutants and axon migration defects of enu-3 mutants were rescued by expression of the H04D03.1 gene product. Enu-3/H04D03.1 encodes a novel predicted putative trans-membrane protein of 204 amino acids. ENU-3 is expressed weakly expressed in many cell bodies along the ventral cord, including those of the DA and DB motor neurons.

scholarly journals ENU-3 is a novel outgrowth and guidance protein in c. elegans

2021 ◽  
Author(s):  
Callista Stephanie Yee
Keyword(s):  
Amino Acids ◽  
Nervous System ◽  
Caenorhabditis Elegans ◽  
Membrane Protein ◽  
Motor Neuron ◽  
Gene Product ◽  
Motor Neurons ◽  
Growth Cones ◽  
C Elegans ◽  
Extracellular Molecules

During the development of the nervous system, the migration of many cells and axons is guided by extracellular molecules. These molecules bind to receptors at the tips of the growth cones of migrating axons and trigger intracellular signalling to steer the axons along the correct trajectories. Previous work has identified a novel mutant, enu-3 (enhancer of Unc), that enhances the motor neuron axon outgrowth defects observed in strains of Caenorhabditis elegans that lack either the UNC-5 receptor or its ligand UNC-6/Netrin, enu-3 single mutants have weak motor neuron axon migration defects. Both outgrowth defects of double mutants and axon migration defects of enu-3 mutants were rescued by expression of the H04D03.1 gene product. Enu-3/H04D03.1 encodes a novel predicted putative trans-membrane protein of 204 amino acids. ENU-3 is expressed weakly expressed in many cell bodies along the ventral cord, including those of the DA and DB motor neurons.

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