Wen C-h et al. (1996) East Coast Worm Meeting "Genetic study of sel-9"

Greenwald IS, Wen C-h

[East Coast Worm Meeting, 1996]

sel-9 mutations were first isolated in a screen for suppressors of lin-12(n676n930), a lin-12 hypomorphic mutation(1). Recently, in a complementation screen for new sel-9 mutations, we have obtained more alleles of sel-9 which show strong interactions with both lin-12 and glp-1 mutations. One class of sel-9 mutations, probably gain-of-function alleles, increase lin-12 and glp-1activity. The other class of mutation, represented by a probable loss-of-function allele, decreases lin-12 and glp-1activity. From genetic analysis, we propose that sel-9 defines a postive regulator or effector in the lin-12 and/or glp-1 pathways. Some of the sel-9 alleles also show new phenotypes in a wild type background, suggesting additional roles for sel-9 other than the involvement in the lin-12 and glp-1 pathways. We have also been trying to clone the sel-9 gene. sel-9 maps to LG V, between the left hand break points of two deficiencies, sDf47 and mDf3, a region covered by a few cosmids and YACs. Preliminary experiments indicate that sel-9 can be rescued by a single cosmid clone. We are trying to verify this result with the new sel-9 alleles. 1) Sundaram, M. and I. Greenwald 1993 Suppressors of a lin-12 hypomorph define genes that interact with both lin-12 and glp-1 in Caenorhabditis elegans. Genetics 135: 765-783.

Wen C-h et al. (1995) International C. elegans Meeting "sel-9 AND sel-10: GENETICS, MAPPING AND CLONING"

Hubbard EJA, Wen C-h, Greenwald IS

[International C. elegans Meeting, 1995]

The lin-12 gene plays a central role in several different cell fate decisions requiring cell interactions and may encode a receptor for intercellular signals. lin-12(n676n930) is a hypomorphic allele of lin-12 at 25C. Five sel genes, including sel-9 and sel-10, were isolated in a screen for suppressors of lin-12(n676n930), and therefore may contribute to cell fate decisions mediated by lin-12 (see also abstract by Grant and Greenwald).

Wen C-h et al. (1997) International C. elegans Meeting "PROGRESS REPORT ON TWO GENES THAT INTERACT WITH LIN-12: SEL-9 AND SUP-17"

Wen C-h, Greenwald IS

[International C. elegans Meeting, 1997]

Two sel-9 mutations were originally isolated as suppressors of a lin-12 hypomorphic allele (Sundaram and Greenwald, 1993), and we have isolated 6 additional alleles of sel-9 by a noncomplementation screen. We have examined the genetic interactions between sel-9 and lin-12 alleles. None of the alleles of sel-9 behave like sDf47, a deficiency of the locus(Hunter and Wood, 1992). These results indicate either that none of the sel-9 alleles are null alleles, or that the deficiency does not behave like a null allele (perhaps because it reduces the activity of another interacting gene). The complex genetics have made sel-9 difficult to clone, and we will present the status of our efforts at the meeting. sup-17 was identified by suppressors of lin-12(d) alleles (Ferguson and Horvitz, 1985; F. Tax, J. Thomas, E. Ferguson and H.R. Horvitz, 1997). We have been investigating interactions of sup-17 with lin-12 and glp-1 hypomorphs, and with other genes that interact with lin-12. We have also begun to try to isolate sup-17, beginning with a 180kb YAC clone that Mark Metzstein (personal communication) used to rescue sup-17 in the process of correlating the genetic and physical maps in the ces-1 region. We have used in vivo recombination in yeast to truncate this YAC clone, and have identified a 60 kb region that is able to rescue sup-17. We hope to have made additional progress towards cloning sup-17 by the meeting.

Wen C-h et al. (1998) East Coast Worm Meeting "Members of the p24 family proteins influence LIN-12/GLP-1 activity in C. elegans"

Wen C-h, Greenwald IS

[East Coast Worm Meeting, 1998]

In eukaryotic cells, newly synthesized proteins are packaged in coated vesicles and exported along secretion pathway to reach the cell surface. Cargo proteins are selectively packaged into transport vesicles, a process that involves both the cargo proteins and the coat proteins. The p24 family of membrane proteins were isolated as membrane components of transport vesicles. Recent studies have suggested the p24 proteins are involved in the selective packaging of cargo proteins into vesicles and they may function as a link between the cargo proteins and the coat proteins. In C. elegans, we have found members of the p24 family are involved in regulating the activity of LIN-12 and GLP-1, two members of the LIN-12/NOTCH family of receptor proteins. One of these p24 proteins corresponds to the sel-9 gene product. We will describe genetic and molecular analysis of the sel-9 gene. Our results are consistent with the proposed function of the p24 family proteins. Based on studies of the p24 proteins in other organisms and our analysis of the interactions between sel-9 and lin-12/glp-1, we propose the p24 proteins are involved in the export of LIN-12/GLP-1 receptors to the cell surface.

Dana L. Miller et al. (2007) International Worm Meeting "Adaptation to hydrogen sulfide increases thermotolerance and lifespan."

Mark B. Roth, Dana L. Miller

[International Worm Meeting, 2007]

Hydrogen sulfide (H₂S), which is naturally produced in animal cells, has been shown to effect physiological changes that improve the capacity of mammals to survive environmental changes. We have investigated the physiological response of C. elegans to H₂S to begin to elucidate the molecular mechanisms of H₂S action. We show that nematodes exposed to H₂S are apparently healthy and do not exhibit phenotypes consistent with metabolic inhibition. However, we observed that animals exposed to H₂S had increased thermotolerance and lifespan and survived subsequent exposure to otherwise lethal concentrations of H₂S. Increased thermotolerance and lifespan is not observed in the sir-2.1(ok434) deletion mutant exposed to H₂S. However, mutants in the insulin signaling pathway (both daf-2 and daf-16), animals with mitochondrial dysfunction (isp-1 and clk-1) and a genetic model of caloric restriction (eat-2) all exhibit H₂S-induced increased thermotolerance. These data suggest that H₂S activates a pathway including SIR-2.1 that is separate from dietary restriction and insulin signaling that results in increased lifespan. Moreover, these studies suggest that SIR-2.1 activity may translate environmental change into physiological alterations that improve survival. It is interesting to consider the possibility that the mechanisms by which H₂S increases thermotolerance and lifespan in nematodes are conserved, and that studies using C. elegans may help explain beneficial effects observed in mammals exposed to H₂S.

Abergel, Z. et al. (2017) International Worm Meeting "Adaptation of the nematode C. elegans to hypoxia and reoxygenation stress reveals an unexpected function of the neuroglobin GLB-5 in innate immunity."

Zuckerman, B., Zelmanovich, V., Abergel, Z., Abergel, R., Gross, E., Smith, Y., Romero, L., Livshits, L.

[International Worm Meeting, 2017]

Deprivation of oxygen (hypoxia) followed by reoxygenation (H/R stress) is a major component in several pathological conditions such as vascular inflammation, myocardial ischemia, and stroke. However how animals adapt and recover from H/R stress remains an open question. Previous studies showed that the neuroglobin GLB-5(Haw) is essential for the fast recovery of the nematode Caenorhabditis elegans (C. elegans) from H/R stress. Here, we characterize the changes in neuronal gene expression during the adaptation of worms to hypoxia and recovery from H/R stress. Our analysis shows that innate immunity genes are differentially expressed during both adaptation to hypoxia and recovery from reoxygenation stress. Moreover, we reveal that the prolyl hydroxylase EGL-9, a known regulator of both adaptation to hypoxia and the innate immune response, inhibits the fast recovery from H/R stress through its activity in the O2-sensing neurons AQR, PQR, and URX. Finally, we show that GLB-5(Haw) acts in AQR, PQR, and URX to increase the tolerance of worms to bacterial pathogenesis. Together, our studies suggest that innate immunity and recovery from H/R stress are regulated by overlapping signaling pathways.

Rasika Kalamegham et al. (2004) East Coast Worm Meeting "EGL-26 belongs to the NlpC/P60 superfamily of putative enzymes and is closely related to a mammalian acyl transferase"

Wendy Hanna-Rose, Rasika Kalamegham

[East Coast Worm Meeting, 2004]

egl-26 was identified in a genetic screen to uncover mutants with vulval morphology defects. In egl-26 mutants the morphology of a single vulval toroid (vulF) is abnormal and a proper connection to the uterus is not made leading to the egg-laying defect. EGL-26 is a member of the NlpC/P60 superfamily of enzymes, which is characterized by a Histidine containing domain and a Cysteine containing domain (H-box and NC domain, respectively). EGL-26 along with other eukaryotic proteins belongs to a distinct subclass of NlpC/P60-related putative enzymes. The mammalian proteins lecithin: retinol acyltransferase or LRAT and H-ras revertant 107 or H-Rev107 are the most closely related to EGL-26. Both LRAT and H-Rev107 contain putative transmembrane domains in addition to the H-box and NC domains. Although EGL-26 contains no putative transmembrane domains, it is localized at the apical membrane of cells where it is expressed. Proper localization of LRAT within the retinal pigment epithelium is essential for its function. Significantly, an S-F substitution at amino acid 275 of EGL-26 found in the egl-26 (n481) allele causes mislocalization of an EGL-26::GFP fusion leading to general cytoplasmic expression as opposed to normal apical membrane localization. The corresponding Serine residue is conserved in both LRAT and H-Rev107. We are attempting to analyze the relationship between the mammalian proteins and EGL-26 by attempting a rescue of egl-26 mutants by expression of either LRAT or H-Rev107 or both. We plan to test the importance of membrane localization by restoring membrane localization to EGL-26n481 via addition of alternative membrane localization signals.

Schwartz, Hillel et al. (2013) International Worm Meeting "Developing Heterorhabditis nematodes as an experimental system for the study of mutualistic symbiosis."

Schwartz, Hillel, Sternberg, Paul

[International Worm Meeting, 2013]

Entomopathogenic nematodes of the genus Heterorhabditis are insect killers that live in mutually beneficial symbiosis with pathogenic Photorhabdus bacteria. Photorhabdus is rapidly lethal to insects and to other nematodes, including C. elegans, but is required for Heterorhabditis growth in culture and for the insect-killing that defines the entomopathogenic lifestyle. The symbiosis between Heterorhabditis and Photorhabdus offers the potential to study the molecular genetic basis of their cooperative relationship. We developing tools to make such studies more feasible: we have been studying multiple nematodes of the genus Heterorhabditis and developing tools for the molecular genetic analysis of Heterorhabditis bacteriophora. Many species of Heterorhabditis and variants of Photorhabdus have been isolated; some pairings show specificity in their ability to establish a symbiotic relationship. To better understand these interactions and other variations in the lifestyles of Heterorhabditis, we have sequenced H. indica, H. megidis, H. sonorensis, and H. zealandica; a H. bacteriophora genome sequence is available. A comparison of these closely related species may help us to identify mechanisms that regulate the response to bacterial interactions and to find variations that correlate with differences in lifestyle or bacterial compatibility. In addition to genomics, we are developing H. bacteriophora as a laboratory organism. H. bacteriophora grows well on plates, has been reported to be susceptible to RNAi and transgenesis, and can develop as a selfing hermaphrodite, and so should be a powerful system for the molecular genetic study of the aspects of biology to which it is uniquely well suited, most prominently symbiosis. This potential is severely diminished by inconvenient sex determination: the self-progeny of hermaphrodites are mostly females with some males; at low density, their progeny are almost exclusively females. We have screened for and isolated a constitutively hermaphroditic mutant for use in molecular genetic studies of symbiosis. This mutant also offers the opportunity to explore the basis of hermaphrodite sex determination in H. bacteriophora.

Schwartz H et al. (2010) Aging, Metabolism, Stress, Pathogenesis, and Small RNAs, Madison, WI "Towards a SNP map for Heterorhabditis bacteriophora"

Sternberg P, Schwartz H

[Aging, Metabolism, Stress, Pathogenesis, and Small RNAs, Madison, WI, 2010]

Heterorhabditis bacteriophora is a species of insect-parasitic nematode that lives in mutually beneficial symbiosis with pathogenic Photorhabdus luminescens bacteria. P. luminescens bacteria are lethal to insects and to other nematodes, including the soil nematode Caenorhabditis elegans, but are required for H. bacteriophora growth. The symbiosis between H. bacteriophora and P. luminescens therefore offers the potential to study the molecular genetic basis of their cooperative relationship. We are interested in developing tools to make such studies more feasible; in particular, we propose to generate tools for genetic mapping in H. bacteriophora. We will test independent isolates of H. bacteriophora to ensure that the isolates are cross-fertile. We will then examine the abilities of these isolates to grow on and to become infected with different wild-type and mutant Photorhabdus bacteria. From these tests we will select an isolate on which we will use next-generation high-throughput sequencing technology for the purpose of refining the existing draft genome sequence and for the creation of a SNP map. We anticipate that this SNP map will enable us and the wider insect-parasitic nematode community to identify induced mutations and natural variations affecting the interactions between H. bacteriophora nematodes and pathogenic Photorhabdus bacteria.

Chu, Yu-De et al. (2013) International Worm Meeting "An RNAi-based screen for the DExD/H-box RNA helicases involved in Caenorhabditis elegans microRNA function."

Chan, Shih-Peng, Chen, Shin-Kai, Chu, Yu-De, Chen, Guan-Rong, Huang, Tao

[International Worm Meeting, 2013]

MicroRNAs (miRNAs) are small non-coding regulatory RNAs that regulate gene expression at the post-transcriptional level and are involved in a broad spectrum of biological processes. Rearrangements of inter- or intra-molecular RNA structures and conformational changes of ribonucleoprotein complexes in the multiple processes of the miRNA pathway have led to the involvement of RNA helicase activities but little is known so far. In eukaryotes, RNA helicases generally belong to the superfamily 2 (SF2) in helicase classification, especially the DExD/H-box helicase family. The DExD/H-box proteins have been shown in association with many cellular processes involving RNA. To better understand the possible roles of DExD/H-box RNA helicases in miRNA function, we employed RNAi screen to identify genetic interaction between C. elegans DExD/H-box RNA helicases and the let-7 miRNA, which controls the timing of cell cycle exit and terminal differentiation. In addition to the RNA helicase p72, a component of Drosha Microprocessor complex, and CGH-1 that has been reported to facilitate the function of miRNA-induced silencing complex (miRISC), we found several DExD/H-box RNA helicases, which are involved in ribosomal RNA processing, pre-mRNA splicing and mRNA surveillance, may also take part in miRNA biogenesis and/or function. (Support: National Science Council, Taiwan. NSC 100-2311-B-002-006-MY3).