Maguire, Sean et al. (2011) International Worm Meeting "Behavioral adaptation of soil nematodes facilitates escape from predacious fungi."

Clark, Christopher M., Maguire, Sean, Alkema, Mark J., Pirri, Jennifer K.

[International Worm Meeting, 2011]

Animal nervous systems need to respond to challenges in their natural environment. This is epitomized by predator-prey interactions where survival depends on the animal's ability to escape. However, we have few insights into how natural selection has shaped the molecular and neural mechanisms of behavior. We investigated predator-prey interactions between C. elegans and predacious fungi that catch and devour nematodes using constricting rings as trapping devices. Gentle touch to the anterior half of the body of C. elegans induces an escape response in which the animal reverses and suppresses exploratory head movements. We found that the constricting rings of Drechslerella doedycoides catch early larval stages with a diameter similar to the trap opening. There is a delay between the ring entry and ring closure, which allows the animal to withdraw from the trap before getting caught. Tyramine-signaling mutants that fail to suppress head movements in response to touch are caught more efficiently than the wild type in constricting fungal rings. Competition experiments show that the suppression of head movements in response to touch is an ecologically relevant behavior that allows the C. elegans to smoothly retract from a fungal noose and evade capture. Behavioral analysis of other soil nematodes suggests that selective pressures imposed by predacious fungi have shaped the evolution of escape behavior of free-living soil nematodes.

Sean Maguire et al. (2009) European Worm Neurobiology Meeting "Tyraminergic control of a C. elegans escape response"

Chris Clark, Jennnifer Pirri, Mark Alkema, Sean Maguire, Jamie Donnely

[European Worm Neurobiology Meeting, 2009]

A key feature of escape responses is the fast translation of sensory information into a coordinated motor output. In C. elegans anterior touch initiates a backward escape response in which lateral head movements are suppressed. The neural wiring diagram and genetic analysis indicate that release the biogenic amine, tyramine, links the neural circuit that regulates the touch response with the neural circuit that regulates head movements. To test the neural circuit that underlies this escape response we generated transgenic animals that express of the light activated Channelrhodopsin2 (ChR2) in the ALM/AVM touch sensory neurons, the AVA backward locomotion command neurons or the tyraminergic RIM neurons. Activation of the ALM/AVM, AVA or RIM induces a backing response and the suppression of head movements in a tyramine dependent manner. Tyramine release coordinates the output of distinct motor programs through the activation of a tyramine-gated chloride channel, LGC-55 and the G-protein coupled receptor SER-2. In the wild, the coordination of these motor programs in response to touch may allow the animal to escape nematophagous fungi that trap nematodes with constricting hyphal rings.

Chang JT et al. (2020) Methods Mol Biol "Correction to: Assessing Tissue-Specific Autophagy Flux in Adult Caenorhabditis elegans."

Chang JT, Kumsta C, Hansen M

[Methods Mol Biol, 2020]

Correction to: Chapter 17 in: Sean P. Curran (ed.), Aging: Methods and Protocols, Methods in Molecular Biology, vol. 2144.

Eddy SR (1994) Worm Breeder's Gazette "Three Families of Reverse Transcriptase Elements in C. elegans"

Eddy SR

[Worm Breeder's Gazette, 1994]

Three families of reverse transcriptase elements in C. elegans Sean Eddy, MRC-LMB, Hills Road, Cambridge CB2 2QH, UK

Zhang H et al. (2008) Mol Biol Cell "RAB-11 permissively regulates spindle alignment by modulating metaphase microtubule dynamics in Caenorhabditis elegans early embryos."

Zhang H, White JG, Squirrell JM

[Mol Biol Cell, 2008]

Monitoring Editor: Sean Munro Alignment of the mitotic spindle along a pre-formed axis of polarity is crucial for generating cell diversity in many organisms (Segal and Bloom, 2001; Betschinger and Knoblich, 2004), yet little is known about the role of the endomembrane system in this process. RAB-11 is a small GTPase enriched in recycling endosomes. When we depleted RAB-11 by RNAi in C. elegans, the spindle of the one-cell embryo failed to align along the axis of polarity in metaphase and underwent violent movements in anaphase. The distance between astral microtubules ends and the anterior cortex was significantly increased in rab-11(RNAi) embryos specifically during metaphase, possibly accounting for the observed spindle alignment defects. Additionally, we found that normal ER morphology requires functional RAB-11, particularly during metaphase. We hypothesize that RAB-11, in conjunction with the ER, acts to regulate cell cycle specific changes in astral microtubule length to ensure proper spindle alignment in C. elegans early embryos.

McEwen JM et al. (2008) Mol Biol Cell "UNC-18 promotes both the anterograde trafficking and synaptic function of syntaxin."

Kaplan JM, McEwen JM

[Mol Biol Cell, 2008]

Monitoring Editor: Sean Munro The SM protein UNC-18 has been proposed to regulate several aspects of secretion, including synaptic vesicle (SV) docking, priming, and fusion. Here we show that UNC-18 has a chaperone function in neurons, promoting anterograde transport of the plasma membrane SNARE protein Syntaxin-1. In unc-18 mutants, UNC-64 (C. elegans Syntaxin-1) accumulates in neuronal cell bodies. Colocalization studies and analysis of carbohydrate modifications both suggest that this accumulation occurs in the endoplasmic reticulum. This trafficking defect is specific for UNC-64 Syntaxin-1, as 14 other SNARE proteins and 2 active zone markers were unaffected. UNC-18 binds to Syntaxin through at least two mechanisms: binding to closed Syntaxin, or to the N-terminus of Syntaxin. It is unclear which of these binding modes mediates UNC-18 function in neurons. The chaperone function of UNC-18 was eliminated in double mutants predicted to disrupt both modes of Syntaxin binding, but was unaffected in single mutants. By contrast, mutations predicted to disrupt UNC-18 binding to the N-terminus of Syntaxin caused significant defects in locomotion behavior and responsiveness to cholinesterase inhibitors. Collectively, these results demonstrate the UNC-18 acts as a molecular chaperone for Syntaxin transport in neurons, and that the two modes of UNC-18 binding to Syntaxin are involved in different aspects of UNC-18 function.

Zhu GD et al. (2009) Mol Biol Cell "SPE-39 family proteins interact with the HOPS complex and function in lysosomal delivery."

Doucette MM, Salazar G, Faundez V, Fiza B, L'Hernault SW, Heilman CJ, Zhu GD, Zlatic SA, Levey AI

[Mol Biol Cell, 2009]

Monitoring Editor: Sean Munro Yeast and animal homotypic fusion and vacuole protein sorting (HOPS) complexes contain conserved subunits, but HOPS-mediated traffic in animals might require additional proteins. Here we demonstrate that SPE-39 homologues, which are found only in animals, are present in RAB5-, 7- and 11-positive endosomes where they play a conserved role in lysosomal delivery and probably function via their interaction with the core HOPS complex. While C. elegans spe-39 mutants were initially identified as having abnormal vesicular biogenesis during spermatogenesis, we show that these mutants also have disrupted processing of endocytosed proteins in oocytes and coelomocytes. C. elegans SPE-39 interacts in vitro with both VPS33A and VPS33B while RNAi of VPS33B causes spe-39-like spermatogenesis defects. The human SPE-39 ortholog, C14orf133, also interacts with VPS33 homologues and both coimmunoprecipitates and cosediments with other HOPS subunits. SPE-39 knockdown in cultured human cells altered the morphology of syntaxin 7-, 8-, and 13-positive endosomes. These effects occurred concomitantly with delayed mannose 6-phosphate receptor-mediated cathepsin D delivery and degradation of internalized epidermal growth factor receptors. Our findings establish that SPE-39 proteins are a previously unrecognized regulator of lysosomal delivery and that C. elegans spermatogenesis is an experimental system useful for identifying conserved regulators of metazoan lysosomal biogenesis.

Prasad BC et al. (1997) International C. elegans Meeting "THE C. ELEGANS unc-3 GENE ENCODES A HOMOLOGUE OF THE O/E FAMILY OF MAMMALIAN TRANSCRIPTION FACTORS"

Prasad BC, Reed RR, Seydoux GC

[International C. elegans Meeting, 1997]

The expression of specialized signal transduction components in mammalian olfactory neurons is thought to be regulated by the O/E (Olf-1/EBF) family of transcription factors. The O/E proteins are expressed in cells of the olfactory neuronal lineage throughout development, and are also expressed transiently in neurons in the developing nervous system during embryogenesis. We have identified a C. elegans homologue of the mammalian O/E proteins, which displays greater than 80% similarity over 350 amino acids. The CeO/E cDNA maps to cosmid F42D1, previously shown to encode unc-3(1). We demonstrate that CeO/E is the product of the unc-3 gene, mutations in which cause defects in the axonal outgrowth of motor neurons as well as defects in dauer formation, a process requiring chemosensory input. Like its mammalian homologues, CeO/E is expressed in certain chemosensory neurons (ASI amphid neurons) throughout development, and is also expressed transiently in developing motor neurons when these cells undergo axonal outgrowth. Currently, we are defining the DNA sequence binding specificity of the CeO/E protein. These observations suggest that the O/E family of transcription factors play a central and evolutionarily conserved role in the expression of proteins essential for axonal pathfinding and neuronal differentiation. (1) Sean Eddy, WBG 12(5):86 (February 1, 1993)

Srayko MA et al. (1997) International C. elegans Meeting "Towards cloning mei-2"

Mains PE, Srayko MA

[International C. elegans Meeting, 1997]

Genetic analysis indicates that mei-2 behaves as an activator of mei-1, a putative ATPase required for meiotic spindle function. All three mei-2 mutations exhibit recessive maternal-effect lethality as a result of meiotic failure. However, the null phenotype of mei-2 is currently unknown. Our goal is to clone and characterize mei-2. The mei-2 locus mapped to the left of let-607 (which we rescued by transformation with cosmid F57B10) and to the right of the duplication hDp39, the endpoint of which lies within K06A5 (S. Clark-Maguire, pers. comm). Three overlapping cosmids that span the region from hDp39 to F57B10 (K06A5, M02H2, and C01B6) were found to rescue mei-2(ct102) when coinjected. The rescue was relatively weak, with twenty-fold more embryos surviving from cosmid-bearing mei-2 mothers than embryos from non-cosmid-bearing mei-2 mothers (20/2000 vs 1/2000). To date, all attempts to narrow down the smallest rescuing fragment via transformation rescue have failed (no pairwise combinations or single cosmids rescue). Other approaches to clone mei-2 are in progress, including RFLP analysis of mei-2 alleles and antisense RNA injection of candidate gene sequences produced by the Genome Sequencing Consortium. Antisense experiments for one candidate, a cdc25 homologue on KO6A5, produced dead embryos from injected mothers, a phenotype consistent with mei-2. Upon close examination, a small percentage (~5%) of antisense embryos exhibit what appears to be an enlarged polar body, a frequent hallmark of meiotic spindle disruption. Progress on the identification of mei-2, as well as genetic screens to generate null alleles, will be presented.

Manser J et al. (1985) Worm Breeder's Gazette "Autosomal Extragenic Suppressors Of her-1(n695) V"

Wood WB, Manser J, Trent C

[Worm Breeder's Gazette, 1985]

We are studying five extragenic mutations that suppress the Tra phenotype of her-1(n695) V (see preceding abstract): ct27 III (gamma- ray induced), n1091 III and ct49 III (allelic, EMS-induced; ct49 was isolated by Sean Burgess), and n1092 V and n1102 V (allelic, EMS- induced). ct27 III has a semi-dominant dpy phenotype in XX animals; XO animals are less severely Dpy and are abnormal males. Both ct27; n695 and ct27/+;n695 XX animals exhibit strong suppression of the n695 Tra phenotype. Because ct27 results in a phenotype somewhat similar to that caused by mutations in the chauvinist dpy genes (dpy's 21, 26, 27, 28) it may suppress n695 with an effect on X-chromosome expression. n1091 III has no apparent effect on XX or XO animals by itself, while ct49 III XX and XO animals are Dpy h we have not eliminated the possibility that this phenotype results from a second closely linked mutation). n1091;n695 XX animals are well suppressed; n1091/+;n695 XX animals are not. n1092 V and n1102 V map near unc-76 (about 5% from her-1). Neither appears to have any effect on XX or XO animals by itself. For n1092 and n1102, both n695 sup and n695 sup/n695 + XX animals show strong suppression. n695n1O91 XO, n695n1O92 XO, and n695n11O2 XO animals are all normal males (that is, they are apparently identical to n695 XO animals). This suggests that the EMS-induced suppressor mutations on III and V affect a process that is active in XX, but not XO, animals. For example, the genes identified by these mutations could be involved in turning off her-1 expression in XX animals.