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Kaleta, C., Li, C.C.Y., Casanueva, O, Le Novere, N., Witting, M., Hastings, J.
[
International Worm Meeting,
2017]
C. elegans has recently been advanced as a premier metazoan model organism for the study of metabolism, with the publication of two whole-genome metabolic models (1, 2). Using these models together with -omics data allows the in-depth data-driven exploration of systems-level metabolism using in silico simulations. In a GENiE workshop to be held April 2017 at the Babraham Institute, Cambridge, UK, the relationships between these two existing metabolic models will be explored with the objective of generating a consensus model. Because the two reconstructions are still incomplete, and certain important pathways and areas of metabolism are currently under-annotated, we aim to identify specific areas that are relevant to the C. elegans community and prioritise them for further annotation in a follow-up community-driven "annotation jamboree" workshop. This poster will describe the main objectives set by the first workshop and opens the invitation to the C. elegans metabolic research community to contribute to the follow-up annotation efforts. 1. Gebauer, J.; Gentsch, C.; Mansfeld, J.; Schmei beta er, K.; Waschina, S.; Brandes, S.; Klimmasch, L.; Zamboni, N.; Zarse, K.; Schuster, S.; Ristow, M.; Schauble, S. & Kaleta, C. (2016), 'A Genome-Scale Database and Reconstruction of Caenorhabditis elegans Metabolism.', Cell Syst 2(5), 312--322. 2. Yilmaz, L. S. & Walhout, A. J. M. (2016), 'A Caenorhabditis elegans Genome-Scale Metabolic Network Model.', Cell Syst 2(5), 297--311.
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[
International Worm Meeting,
2019]
The development of Caenorhabditis elegans is very robust and it takes two days to reach adulthood under standard laboratory conditions. However, in the wild, developing animals face many challenges that are not necessarily present in a sterile and controlled laboratory environment, such as pathogen stress and dietary limitations. We investigated how development is influenced by pathogen stress using C. elegans larvae and 35 Pseudomonas aeruginosa strains under modified slow-killing conditions. We observed that C. elegans larvae exhibit three developmental phenotypes when fed with different P. aeruginosa strains: normal development, slow development and very slow development. Normal and slow development are classified as reaching adulthood in 2 days and 3 days, respectively; the third group causes extreme developmental slowing and P. aeruginosa strain CF18 fed larvae do not reach adulthood. To determine the mechanism of very slow development caused by CF18, we investigated three possible mechanisms: larval gut colonization status, bacterial nutrient deficiencies and pathogenesis/toxins1,2. We found that the larva's gut is not colonized by CF18. The larvae were able to reach adulthood on UV radiated CF18 lawn, suggesting that it is not nutrient deficiency but the pathogenicity of the strain that causes this developmental slowing. Secreted compounds by CF18 in the medium were also required for the very slow development phenotype. To determine the bacterial effectors causing this developmental delay, we have generated a transposon insertion library in the CF18 background and examined the developmental phenotype of larvae when fed with these mutants. We have found that transposon insertion in certain bacterial genes, including quorum sensing and two-component system genes, allow C. elegans larvae to overcome developmental slowing. 1. Tan, M.-W., Mahajan-Miklos, S. & Ausubel, F. M. Killing of Caenorhabditis elegans by Pseudomonas aeruginosa used to model mammalian bacterial pathogenesis. Proc. Natl. Acad. Sci. 96, 715-720 (1999). 2. Watson, E. et al. Interspecies systems biology uncovers metabolites affecting C. elegans gene expression and life history traits. Cell 156, 759-770 (2014).
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[
International Worm Meeting,
2017]
Extracellular vesicles are emerging as an important aspect of intercellular communication by delivering a parcel of proteins, lipids even nucleic acids to specific target cells over short or long distances (Maas 2017). A subset of C. elegans ciliated neurons release EVs to the environment and elicit changes in male behaviors in a cargo-dependent manner (Wang 2014, Silva 2017). Our studies raise many questions regarding these social communicating EV devices. Why is the cilium the donor site? What mechanisms control ciliary EV biogenesis? How are bioactive functions encoded within EVs? EV detection is a challenge and obstacle because of their small size (100nm). However, we possess the first and only system to visualize and monitor GFP-tagged EVs in living animals in real time. We are using several approaches to define the properties of an EV-releasing neuron (EVN) and to decipher the biology of ciliary-released EVs. To identify mechanisms regulating biogenesis, release, and function of ciliary EVs we took an unbiased transcriptome approach by isolating EVNs from adult worms and performing RNA-seq. We identified 335 significantly upregulated genes, of which 61 were validated by GFP reporters as expressed in EVNs (Wang 2015). By characterizing components of this EVN parts list, we discovered new components and pathways controlling EV biogenesis, EV shedding and retention in the cephalic lumen, and EV environmental release. We also identified cell-specific regulators of EVN ciliogenesis and are currently exploring mechanisms regulating EV cargo sorting. Our genetically tractable model can make inroads where other systems have not, and advance frontiers of EV knowledge where little is known. Maas, S. L. N., Breakefield, X. O., & Weaver, A. M. (2017). Trends in Cell Biology. Silva, M., Morsci, N., Nguyen, K. C. Q., Rizvi, A., Rongo, C., Hall, D. H., & Barr, M. M. (2017). Current Biology. Wang, J., Kaletsky, R., Silva, M., Williams, A., Haas, L. A., Androwski, R. J., Landis JN, Patrick C, Rashid A, Santiago-Martinez D, Gravato-Nobre M, Hodgkin J, Hall DH, Murphy CT, Barr, M. M. (2015).Current Biology. Wang, J., Silva, M., Haas, L. A., Morsci, N. S., Nguyen, K. C. Q., Hall, D. H., & Barr, M. M. (2014). Current Biology.
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[
European Worm Meeting,
2002]
M. nematophilum is a novel pathogen of C. elegans recently described by J. Hodgkin et al. (1). The bacterium is able to attach to the post-anal region of C. elegans and to induce massive swelling of the underlying tissues by an unknown mechanism. The disease causes constipation and slows growth of affected worms. M. nematophilum belongs to the Gram-positive coryneform group of bacteria and is poorly characterised.
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[
International Worm Meeting,
2009]
How are polarized epithelia established and maintained? This question is of critical importance, as the loss of epithelial polarity is associated with metastasis(1). There are many well-studied protein complexes that lie in specific membrane compartments with roles integral to the epithelial cell. The E-cadherin-containing adherens junction serves to link neighboring epithelial cells together while the more basal tight junction functions to separate the apical and basolateral surfaces. For some cells, E-cadherin is the major initiator of cell polarity and epithelium formation via cell-cell adhesion(2). However, recent studies have discovered E-cadherin independent polarity pathways(3-6). C. elegans offers a powerful system to study this cadherin-independent mechanism, as E-cadherin is dispensible for the initiation of epithelial polarity in nematodes(4). We study cadherin-independent epithelium formation during pharynx development. Nine pharyngeal arcade cells undergo a mesenchymal-to-epithelial transition to link the pharynx to the outer epidermis(7). Ablation of the arcade cells results in a Pharynx unattached (Pun) phenotype, in which the pharynx fails to connect to the epidermis(7). Pun animals die as they are unable to eat. Our lab has undertaken a genetic screen for Pun mutants that fail to form the arcade cell epithelium (Portereiko and Mango, unpublished). This screen revealed that loss of the central-spindlin component ZEN-4/MKLP1 induces a Pun phenotype because the arcade cells fail to polarize(8). We are currently studying where and when ZEN-4 is needed for arcade cell polarization. We have also undertaken a structure/function analysis of this mitotic kinesin in order to elucidate its role in epithelialization. In addition, we are in the process of cloning several mutants that were isolated in the Pun mutagenesis screen. (1). J. M. Lee, S. Dedhar, R. Kalluri, E. W. Thompson, J Cell Biol 172, 973 (Mar 27, 2006). (2). L. N. Nejsum, W. J. Nelson, J Cell Biol 178, 323 (Jul 16, 2007). (3). A. F. Baas et al., Cell 116, 457 (Feb 6, 2004). (4). M. Costa et al., J Cell Biol 141, 297 (Apr 6, 1998). (5). T. J. Harris, M. Peifer, J Cell Biol 167, 135 (Oct 11, 2004). (6). W. B. Raich, C. Agbunag, J. Hardin, Curr Biol 9, 1139 (Oct 21, 1999). (7). M. F. Portereiko, S. E. Mango, Dev Biol 233, 482 (May 15, 2001). (8). M. F. Portereiko, J. Saam, S. E. Mango, Curr Biol 14, 932 (Jun 8, 2004).
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Landuyt, Bart, Horvitz, H.Robert, Meelkop, Ellen, Schoofs, Liliane, Husson, Steven J., Gottschalk, Alexander, Temmerman, Liesbet, Ringstad, Niels
[
International Worm Meeting,
2011]
Egg laying has mainly been studied at the behavioral, neuronal and neurochemical levels, but little is known about the biochemical control of the relevant neuropeptidergic signaling systems. Biosynthesis of endogenous peptides requires processing enzymes, such as proprotein convertase 2, which is encoded by
egl-3 (1, 2), and a carboxypeptidase encoded by
egl-21 (3, 4). Mutants defective in these genes have egg-laying defects, consistent with the finding that FMRFamide-like peptides (FLPs) have been linked to egg laying behavior. C. elegans enzymes that carry out the last step in the production of biologically active peptides, the carboxy-terminal amidation reaction, have not been characterized. This multistep reaction involves hydroxylation of the glycine a-carbon by a peptidyl-a-hydroxylating monooxygenase (PHM), followed by a cleavage reaction performed by peptidyl a-hydroxyglycine a-amidating lyase (PAL) to generate a glyoxylate molecule and the a-amidated peptide. In vertebrates, both enzymatic activities responsible for the carboxyterminal amidation reaction are contained in one bifunctional enzyme, peptidylglycine a-amidating monooxygenase (PAM). By contrast, invertebrates generally express two separate enzymes encoded by two different genes. Here we report the identification and characterization of C. elegans amidating enzymes using bioinformatics to identify candidate genes and mass spectrometry to compare the neuropeptides in wild-type and newly generated mutants. Mutants lacking a functional PHM displayed an altered neuropeptide profile, showed impaired egg laying behavior and had a decreased brood size. Interestingly, PHM mutants still displayed fully processed amidated neuropeptides, probably as a result of the presence of a bifunctional PAM, the main amidating enzyme in vertebrates. Our data indicate the existence of a robust complementation system for the amidation reaction of neuropeptides in nematodes and suggest the involvement of amidated neuropeptides in egg laying. (1) S. J. Husson et al., J. Neurochem. 98, 1999 (2006); (2) J. Kass et al., J. Neurosci. 21, 9265 (2001); (3) S. J. Husson et al., J. Neurochem. 102, 246 (2007); (4) T. C. Jacob, J. M. Kaplan, J. Neurosci. 23, 2122 (2003).
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[
International C. elegans Meeting,
2001]
Heparan sulfate binds and activates a large variety of growth factors, enzymes and extracellular matrix proteins. These interactions largely depend on the specific arrangement of sulfated moieties and uronic acid epimers within the chains. These oligosaccharide sequences are generated in a step-wise manner, initiated by the formation of a linkage tetrasaccharide which is then extended by copolymerization of alternating
a1,4GlcNAc and
b1,4GlcA residues. As the chains polymerize, they undergo a series of sulfation and epimerization reactions. The first set of modifications involves the removal of acetyl units from subsets of GlcNAc residues, and the addition of sulfate groups to the resulting free amino groups. These reactions are catalyzed by a family of enzymes designated as GlcNAc N-deacetylase/N-sulfotransferases (NDST), since they simultaneously. Four members of the family have been identified in vertebrates, with single orthologs present in Drosophila and C. elegans. We have revealed tissue-specific expression pattern and unique enzymatic properties of these four isozymes1,2). In fly, loss of NDST (sulfateless) results in unsulfated chains and defective signaling by multiple growth factors and morphogens. I reconstituted cDNA for worm NDST from EST clones and 5' RACE products. Enzymatic activities will be discussed. 1) Aikawa, J. & Esko, J. D J. Biol. Chem. 274, 2690-2695 (1999) 2) Aikawa, J., Grobe, K., Tsujimoto, M. & Esko, J. D J. Biol. Chem. 276, 5876-5882 (2001)
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[
International C. elegans Meeting,
1997]
We are developing a method to control gene expression in a temperature dependent manner. Our strategy is to regulate reporter expression with a well-defined promoter at the 5' end and a mutant
fem-3 3'UTR at the 3' end. The
fem-3(gf) mutations map to the
fem-3 3'UTR and release
fem-3 from post-transcriptional repression at 25 C, but not at 15 C (1,2). We have tested expression of a
lag-2 promoter::GFP construct that carries either a strong or a weak
fem-3(gf) 3'UTR. The
lag-2 promoter drives expression in the distal tip cells of adults (3-5). We find that transgenes express GFP at much lower levels at 15 C than at 25 C when carrying a
fem-3(gf) 3'UTR. We are currently trying to optimize repression at 15 C using the
lag-2 promoter and GFP as a reporter. In addition, we are testing whether temperature sensitive repression can be achieved in other tissues, and we are starting to explore the biological activity of various proteins expressed in the distal tip cell. 1. Ahringer, J., and Kimble, J. (1991). Nature 349, 346-348. 2. Barton, M. K., Schedl, T. B., and Kimble, J. (1987). Genetics 115, 107-119. 3. Fitzgerald, K., and Greenwald, I. (1995). Development 121, 4275-4282. 4. Gao, D. and J. Kimble, midwest worm meeting 1996. 5. Henderson, S. T., Gao, D., Lambie, E. J., and Kimble, J. (1994). Development 120, 2913-2924.
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[
International Worm Meeting,
2009]
Interactions between proteins are a key component of most or all biological processes. A key challenge in biology is to generate comprehensive and accurate maps (interactomes) of all possible protein interactions in an organism. This will require iterative rounds of interaction mapping using complementary technologies, as well as technological improvements to the approaches used. For example, we recently developed a novel yeast two-hybrid approach that adds a new level of detail to interaction maps by defining interaction domains(1). Currently, I am working to generate an interaction map of proteins involved in controlling cell polarity in C. elegans to improve our understanding of the molecular mechanisms that establish and maintain cell polarity in multicellular organisms. I will combine two fundamentally different interaction mapping techniques: the yeast two-hybrid system (Y2H) and affinity purification/mass spectrometry (AP/MS). This will provide more detail by identifying both direct interactions between pairs of proteins by Y2H, and the composition of protein complexes by AP/MS. Moreover, interactions missed by one technology may be detected by the other, leading to a more complete interaction map. I will integrate the physical interactions with phenotypic characterizations. To this end I will systematically characterize the interaction network in vivo using two distinct models of polarity: asymmetric division of the one-cell embryo, and stem-cell-like divisions of a multicellular epithelium (in collaboration with M. Wildwater and S. van den Heuvel). M. Boxem, Z. Maliga, N. Klitgord, N. Li, I. Lemmens, M. Mana, L. de Lichtervelde, J. D. Mul, D. van de Peut, M. Devos, N. Simonis, M. A. Yildirim, M. Cokol, H. L. Kao, A. S. de Smet, H. Wang, A. L. Schlaitz, T. Hao, S. Milstein, C. Fan, M. Tipsword, K. Drew, M. Galli, K. Rhrissorrakrai, D. Drechsel, D. Koller, F. P. Roth, L. M. Iakoucheva, A. K. Dunker, R. Bonneau, K. C. Gunsalus, D. E. Hill, F. Piano, J. Tavernier, S. van den Heuvel, A. A. Hyman, and M. Vidal, A protein domain-based interactome network for C. elegans early embryogenesis. Cell, 2008. 134(3): p. 534-545. .
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[
European Worm Meeting,
2004]
Calcium is a ubiquitous intracellular signal responsible for controlling a diverse array of processes. The specificity of Ca2+ signals is determined, in part, by their spatio temporal pattern, which is achieved using different storage compartments and specialised binding and gating molecules. The inositol 1, 4, 5-trisphosphate (IP3) receptor (IP3R) plays a key role in regulating the flux of Ca2+ from the endoplasmic reticulum (ER) into the cytoplasm. It follows that the localisation of IP3Rs may be critical in determining the specificity of Ca2+ signals. Our aim is to explore the relationship between IP3R subcellular localisation and the function of this pathway in the biology of a whole animal. To this end we are establishing a system in C. elegans in which IP3Rs are tagged with GFP. The large size and complex pleiotropic phenotypes associated with the IP3R make this a challenging goal. C. elegans IP3Rs are encoded by a single gene,
itr-1. Previously the expression pattern of
itr-1 has been identified in transgenic animals expressing truncated forms of ITR-1 fused to GFP (1, 2, 3) and by using anti-ITR-1 antibodies (2). To establish a system that is closer to the 'wild-type' situation we made transgenic animals expressing full-length ITR-1 fused to GFP. This construct was generated using PCR fusion and in vivo homologous recombination. To test the ability of the construct to function we used it to rescue the Sa73 mutant phenotypes, which include disrupted defecation, pharyngeal pumping and fertility. Thus we are able to directly link the localisation of ITR-1 with its functions. 1.Dal Santo, P., Logan, M. A., Chisholm, A. D. & Jorgenson, E. M. (1999) Cell 98, 757-767. 2.Baylis, H. A., Furuichi, T., Yoshikawa, F., Mikoshiba, K. & Sattelle, D. B. (1999) J. Mol. Biol. 294, 467-476. 3.Gower, N. J. D., Temple, G. R., Schein, J. E., Marra, M., Walker, D. S. & Baylis, H. A. (2001) J. Mol. Biol. 306, 145-157.