Simon JM et al. (2002) Proc Natl Acad Sci U S A "Evidence of a mate-finding cue in the hermaphrodite nematode Caenorhabditis elegans."

Simon JM, Sternberg PW

[Proc Natl Acad Sci U S A, 2002]

When males of the roundworm Caenorhabditis elegans come into association with their hermaphroditic counterparts they cease foraging behavior and begin to mate. Here we detail several assays used to demonstrate that a diffusible cue is correlated with this process. This cue is sexually dimorphic, given off only by the hermaphrodite and eliciting a response only in the male. Males are attracted to, reverse direction of movement frequently, and remain in regions of agar conditioned with hermaphrodites. From our studies we suggest a form of kinesis that works by attracting males to their mating partners from a distance and functions, once males arrive, in holding attracted males in close proximity. The hermaphrodite vulva is not required for the cue. Males from general sensory mutants osm-5 and osm-6 fail to respond to the cue, whereas male-specific mutants lov-1 and pkd-2 respond. Finally, that males from multiple isolates of C elegans also respond similarly to this cue indicates that this cue is robust and has been maintained during recent evolution.

Matthews LR et al. (1994) Worm Breeder's Gazette "A Potential C. elegans E2F Homolog: Is it zyg-9?"

Galas S, Matthews LR

[Worm Breeder's Gazette, 1994]

A potential C. elegans E2F homolog: Is it zyg-9? Lisa Matthews and Simon Galas, CRBM, CNRS Montpellier, France

da Silva AF et al. (2022) Neurotoxicology "JM-20 affects GABA neurotransmission in Caenorhabditis elegans."

Arantes LP, Soares MV, Nunez-Figueredo Y, Cordeiro LM, da Silveira TL, Soares FAA, Baptista FBO, Machado ML, Zamberlan DC, da Silva AF, Rodriguez EO

[Neurotoxicology, 2022]

Along with the discovery of new candidate molecules for pharmaceuticals, several studies have emerged showing different mechanisms of action and toxicological aspects. 3-ethoxycarbonyl-2-methyl-4- (2-nitrophenyl)4,11-dihydro-1H-pyrido [2,3-b] [1,5] benzodiazepine (JM-20) is a hybrid molecule. It is derived from 1,5-benzodiazepines and structurally differentiated by the addition of 1,4-dihydropyridine bonded to the benzodiazepine ring. This gives this molecule potential neuroprotective, antioxidant, and anxiolytic activity. As this is a promising multi-target molecule, further studies are necessary to improve the knowledge about its mechanism of action. In our study, we used Caenorhabditis elegans (C. elegans) to investigate the effects of chronic treatment with JM-20. Nematodes from the wild-type strain (N2) were treated chronically at different concentrations of JM-20. Our results show that JM-20 does not cause mortality, but higher concentrations can delay the development of worms after 48h exposure. We assessed basic behaviors in the worm, and our data demonstrate decreased defecation cycle. Our results suggest that JM-20 acts on the C. elegans GABAergic system because GABA neurotransmission is associated with the worm intestine. We also observed increased locomotor activity and decreased egg-laying after JM-20 treatment. When both behaviors were evaluated in mutants with have reduced levels of GABA (unc-25), this effect is no observed, suggesting the GABAergic modulation. Still, the JM-20 exert similar effect of Diazepam in basic behaviors observed. To reinforce neuromodulatory action, computational analysis was performed, and results showed a JM-20 binding on allosteric sites of nematodes GABA receptors. Overall, this work provided a better understanding of the effects of JM-20 in C. elegans as well as showed the effects of this new molecule on the GABAergic system in this animal model.

Berger S et al. (2018) Lab Chip "Correction: Long-term C. elegans immobilization enables high resolution developmental studies in vivo."

Aegerter-Wilmsen T, DeMello A, Berger S, Casadevall I Solvas X, Hengartner M, Hajnal A, Lattmann E

[Lab Chip, 2018]

Correction for 'Long-term C. elegans immobilization enables high resolution developmental studies in vivo' by Simon Berger et al., Lab Chip, 2018, 18, 1359-1368.

Sternberg PW et al. (2000) West Coast Worm Meeting "Evidence of a Mate-finding Cue in the Free-Living Soil Nematode C. elegans"

Simon JM, Sternberg PW

[West Coast Worm Meeting, 2000]

Use of mate-finding cues is well documented throughout the nematode literature, but no assays for C. elegans have come into common practice. Here we report two assays that suggest young adult males can detect young adult hermaphrodites through some unidentified cue. Accumulation of 14 males (per trial) to agar conditioned with 5 hermaphrodites (the muscle mutant unc-52 was used to construct a point source), which were sequentially removed, suggests a cue given off by hermaphrodites and detected by males [mean number of males observed in 1-cm diameter scoring circles shifted from 3.2+2.2 in control trials (n=29) to 6.5+2.5 in conditioned-agar trials (n=28); p<0.0001 (2a)]. Similar assays testing the effects of such cues on solitary males were also constructed. Single males were followed for 10 minutes and total elapsed time and number of reversals were noted [mean time and reversals in scoring regions (again 1-cm diameter circles) shifted from 4 seconds and 0.2 reversals in control trials (n=30) to 90 seconds and 8.7 reversals in conditioned-agar trials (n=31); p<0.002 and p<0.001, respectively (2a)]. Pilot studies suggest some form of kinesis, but the possibility of an additional short-range taxis, especially in a gas-liquid soil environment, should not be eliminated.

Killeen M et al. (2002) Dev Biol "UNC-5 function requires phosphorylation of cytoplasmic tyrosine 482, but its UNC-40-independent functions also require a region between the ZU-5 and death domains."

Culotti J, Pawson T, Tong J, Steven R, Killeen M, Krizus A, Scott I

[Dev Biol, 2002]

Members of the UNC-5 protein family are transmembrane receptors for UNC-6/netrin guidance cues. To analyze the functional roles of different UNC-5 domains, we sequenced mutations in seven severe and three weak alleles of unc-5 in Caenorhabditis elegans. Four severe alleles contain nonsense mutations. Two weak alleles are truncations of the cytodomain, but one is a missense mutation in an extracellular immunoglobulin domain. To survey the function of different regions of UNC-5, wild-type and mutant unc-5::HA transgenes were tested for their ability to rescue the unc-5(e53) null mutant. Our data reveal partial functional requirements for the extracellular domains and identify a portion of the cytoplasmic juxtamembrane (JM) region as essential for rescue of migrations. When nine cytodomain tyrosines, including seven in the JM region, are mutated to phenylalanine, UNC-5 function and tyrosine phosphorylation are largely compromised. When F482 in the JM region of the mutant protein is reverted to tyrosine, UNC-5 tyrosine phosphorylation and in vivo function are largely recovered, suggesting that Y482 phosphorylation is critical to UNC-5 function in vivo. Our data also show that part of the ZU-5 motif is required for UNC-40-independent signaling of UNC-5.

Juan Wang et al. (2003) International Worm Meeting "Hermaphrodite Signal for male mating behavior"

Juan Wang, Maureen M Barr

[International Worm Meeting, 2003]

The male mating behavior of C. elegans is composed of several sub-steps: response to hermaphrodite contact; backing; turning; location of vulva (LOV); spicule insertion; and sperm transfer (1). The hermaphrodite may play an active role in male mating behavior by providing certain cues for attracting or holding male mating partners (2). Our goal is to identify the hermaphrodite cues for response and LOV, and the genetic and molecular basis of these mating signals and behaviors.lov-1 is required for C. elegans male mating behavior sub-steps of response and LOV step. lov-1 encodes a 3178 amino acid protein, with a large extracellular amino terminus followed by multiple transmembrane spanning domains. The LOV-1 N-terminus contains a mucin-like serine/threonine rich region, an ATP/GTP binding site, a number of glycosylation sites, and a G-protein coupled receptor proteolysis site (GPS) preceding the first putative transmembrane domain. Over expression of the first 600 amino acids results in a dominant negative phenotype(3). The function of this large extracellular amino terminus remains unknown. One model is that the extracellular portion binds a protein to regulate the activity of the LOV-1 receptor. To test this hypothesis, we will isolate proteins that interact with extracellular region of LOV-1. Discrete domains of the LOV-1 N-terminus will be expressed in a Baculovirus expression system and will be used as a bait to screen for interacting proteins.To identify the sensory cues that the hermaphrodite provides the male, wild type males were paired with various hermaphrodite mutants, and behavior assays were performed. Interestingly, one category of srf(surface antigenicity abnormal) mutant provides a poor response signal, but appear to have no effect on other steps of male mating. Characterization of what surface proteins have been lost is in progress.I am also screening for mutant males that show defects in the response and LOV steps. Among them, n4132 (a kind gift from Hillel Schwartz and Bob Horvitz) is a good candidate. Characterization and cloning is in progress and will be described. References: 1. Liu, KS & Sternberg, PW. (1995). Neuron 1, 79-89; 2. Simon, JM& Sternberg, PW. (2002). Proc Natl Acad Sci U S A 99, 1598-603; 3. Barr, MM & Sternberg, PW. (1999). Nature 401, 386-9.

Hartman PS et al. (1995) International C. elegans Meeting "UV RADIATION INHIBITS CELL DIVISION IN THE P1 LINEAGE MORE THAN IN THE AB LINEAGE"

Buckles D, Hartman PS

[International C. elegans Meeting, 1995]

Two-cell embryos were irradiated with germicidal (254nm) radiation and subsequent cell divisions were determined using Nomarski DIC microscopy. A dose of 30 Jm-2 (which gave ca. 10% survival) delayed P1 and P2 divisions by 27%, versus only 8% for the equivalent AB divisions. Similarly, although exposure to 150 Jm-2 abolished cytokinesis in some AB descendants (resulting in occasional binucleated cells), the next two cell cycles were only 22% longer than in unirradiated controls. Conversely, the P1 and P2 cell cycles averaged 95% longer. The delays in the EMSt, E, and MSt cell cycles were similar to those in the AB lineage, suggesting the longer delays were limited to the P4 progenitors. "Cell-cycle checkpoints" have been documented in other organisms. These afford additional time for restitution of DNA damage. Such checkpoints are apparently largely inoperative in the AB lineage (which generates soma exclusively) but at least partially functional in the cells which give rise to the germ line.

Svendsen BA et al. (1988) Worm Breeder's Gazette "effects of UV radiation on embryonic DNA synthesis and cell division (subtitle: tough guy polymerases from the worm?)."

Reddy J, Hartman PS, Svendsen BA

[Worm Breeder's Gazette, 1988]

Synchronous populations of young embryos were exposed to various fluences of 254 radiation and incubated in the presence of tritiated thymidine. At selected times, samples were processed to determine the effects of irradiation on DNA synthesis (measured as the incorporation of tritium into TCA precipitable material) and cell division [measured by counting nuclei a la Gossett and Hecht (1980. J. Histochem. Cytochem. 28, 507-510)]. Despite the fact that over 50% of embryos failed to develop into adults after fluences of 25 Jm-2 or greater, they displayed control (unirradiated) levels of both cell division and replication at fluences of up to 250 Jm-2. This resistance was not due to UV light attenuation, since both parameters were strongly inhibited in two UV radiation hypersensitive mutants (rad-1 and rad-3) by fluences of 10 Jm-2 and greater. Other systems (e.g., bacteria, mammalian cells, yeast) are much more sensitive to the effects of UV radiation on DNA replication. Analysis of the sizes of newly synthesized DNA in irradiated and unirradiated embryos may provide an explanation for this extreme radiation resistance. Synchronous embryos were irradiated, pulse labeled with tritiated thymidine, and chased for various time intervals. After lysis with proteinase K and SDS, samples were subjected to centrifugation through alkaline sucrose gradients. Inclusion of [14C]-labeled T4 and T7 DNA's allowed determination of molecular weights. Fluences of up to 270 Jm-2 failed to reduce the molecular weight of newly synthesized DNA relative to unirradiated controls. This was unexpected, since damage to the parental strand in other organisms suppresses the size of nascent molecules by preventing elongation of DNA polymerase. It can be calculated, based upon the induction frequency of cyclobutane dimers as well as the size of the newly synthesized DNA, that greater than ten cyclobutane dimers were induced in the template opposite each nascent fragment. This leads to the provocative possibility that a DNA polymerase from C. elegans is capable of trans-lesion synthesis through radiation-induced DNA damage. These data are in keeping with the observation, described in the preceding paragraph, that DNA synthesis and cell division during embryogenesis are refractory to super-lethal doses of UV radiation.

Gaud A et al. (2004) Neuromuscul Disord "Prednisone reduces muscle degeneration in dystrophin-deficient Caenorhabditis elegans."

Carre-Pierrat M, Simon JM, Gaud A, Segalat L, Wermuth CG, Witzel T

[Neuromuscul Disord, 2004]

Duchenne muscular dystrophy is a degenerative muscular disease caused by mutations in the dystrophin gene. There is no curative treatment against Duchenne muscular dystrophy. In several countries, the steroid prednisone (or analogs) is prescribed as a palliative treatment. In the model animal Caenorhabditis elegans, mutations of the dys-1 dystrophin-like gene lead to a muscular degenerative phenotype when they are associated with a mild MyoD mutation. This cheap and fast-growing model of dystrophinopathy may be used to screen for molecules able to slow muscle degeneration. In a blind screen of approximately 100 compounds covering a wide spectrum of targets, we found that prednisone is beneficial to the C elegans dystrophin-deficient muscles. Prednisone reduces by 40% the number of degenerating cells in this animal. This result is a proof-of-principle for the use of C. elegans as a tool in the search for molecules active against the effects of dystrophin-deficiency. Moreover, since C. elegans is not susceptible to inflammation, this suggests that prednisone exerts a direct effect on muscle survival.