Gray, Jeremy C et al. (2013) International Worm Meeting "Cross Species NILs - A Resource for Speciation, Evolution and Development."

Cutter, Asher D, Gray, Jeremy C, Bundus, Joanna

[International Worm Meeting, 2013]

Caenorhabditis sp 9 and Caenorhabditis briggsae are capable of forming hybrids at low rates, despite being separate species. Reproductive isolation is of long standing interest in evolutionary biology and the presence of interbreeding species in this genus presents a unique opportunity to probe the genetics of speciation in a well understood background. Here we detail the construction and genotyping of 200 near isogenic lines, consisting of small introgressions of one genome into the opposite species in both mitochondrial backgrounds. Introgressions were achieved by random mating and subsequent backcrosses. Next generation sequencing will be undertaken in order to determine which regions are introgressed, and regions which are under or overrepresented. Strains have been phenotyped for reproductive isolation, cytonuclear incompatibility and general developmental defects. The main thrust of the project is to identify and analyse Bateson-Dobzhansky-Muller incompatibilities within the genus, as well as to identify the genetic basis of the mating system differentiation in the two species. It is anticipated these strain will be made available to the community at large along with genotype information to allow further studies into the divergence of these two species.

Pitt, Jason N. et al. (2011) International Worm Meeting "Hypoxia avoidance response in C. elegans requires goa-1 and dgk-1."

Pitt, Jason N., Roth, Mark B.

[International Worm Meeting, 2011]

Oxygen (O2) is essential for the growth and development nearly all metazoans. O2 concentrations in the environment fluctuate and C. elegans exhibits an aerotaxis behavior dependent on the activity of soluble guanylate cylcases, npr-1 and glb-5. We show that, in addition to the previously described aerotaxis pathway, C. elegans displays a genetically distinct acute hypoxia avoidance response (HAR). When worms are placed in hypoxic atmospheres containing less than 5% O2 they immediately switch from a dwelling to roaming behavior. Roaming speed is inversely correlated with %O2 down to 1% O2 and is positively correlated with O2 concentrations <1%. In addition to its requirement for oxidative phosphorylation, molecular O2 is required for the synthesis of the monoamine neurotransmitters which regulate the switch from dwelling to roaming behaviors. The inhibition of roaming by monoamine neurotransmitters requires the activity of the heterotrimeric G-protein GOA-1. We find that loss of function mutations in goa-1 eliminate HAR. goa-1 animals also display a premature entry into suspended animation (SA) at O2 concentrations 0.1%. GOA-1 negatively regulates the activity of the PLC-b EGL-8 through EGL-30. egl-8 animals display a severely attenuated HAR and also prematurely enter SA. EGL-8 signaling through diacylglycerol (DAG) is negatively regulated by the DAG kinase DGK-1. In moderate hypoxia (&#179;5% O2) dgk-1 worms, like npr-1 worms, show a pronounced decrease in locomotion. However, unlike npr-1 worms, at < 5% O2, dgk-1 worms show an inverse HAR; locomotion is increased in room air but suppressed in hypoxia. Hypoxia survival in C. elegans and other metazoans requires the transcription factor HIF-1. hif-1 loss of function animals show no defects in HAR, however, animals that lack the function of the prolylhydroxylase EGL-9, the negative regulator of HIF-1, show an immediate arrest of locomotion when transferred to hypoxia. This arrest is transient and egl-9 animals slowly increase speed during hypoxia eventually reaching wildtype levels of locomotion. Because dgk-1 worms show a similar arrest immediately upon transition to hypoxia, we tested the affect of hypoxia on embryonic diapause, a phenotype which requires HIF-1. We found that dgk-1 worms, like hif-1 worms, exhibit a precocious diapause at 0.5% O2. This suggests that the GOA-1/DGK-1 pathway might influence HIF-1.

DePellegrin Connelly, Tracey et al. (2009) International Worm Meeting "GENETICS, the peer-edited journal of the Genetics Society of America, reports on updates and special projects, including article links to WormBase."

DePellegrin Connelly, Tracey, Schedl, Tim

[International Worm Meeting, 2009]

GENETICS, the peer-edited journal of the Genetics Society of America has partnered with WormBase (Arun Rangarajan, Hans-Michael Muller and Paul Sternberg) to produce interactive journal articles (in full text/HTML, XML and PDF outputs). A reader who clicks on a gene or protein name, allele, transgene (or potentially any object found in the database) is taken directly to the corresponding page in WormBase. This innovative project integrates two major modes of communication used in the biological sciences: journal articles and databases. The project offers several benefits to readers, including fast access to relevant information associated with a genetic object in the text. This information can be general, providing an overview (e.g. gene summary), or highly specific, providing an important experimental detail (e.g. the molecular lesion of an allele). Also, the project promotes standardization of individual object nomenclature (e.g. gene names) and simplifies connections when there is a nomenclature change. Finally, the objects remain connected but evolve with advancesin knowledge. The benefits to WormBase include increased use of and interest in the database, more efficient and extensive corrections of information in the database by the community, facile incorporation of new information, reverse integration of the database with the primary data in the literature, all with minimal ongoing cost. We will show examples of the article links to WormBase, and discuss a number of other initiatives being undertaken by the journal GENETICS.

Attila L Kovcs et al. (2005) International Worm Meeting "Electron microscopy of autophagy in Caenorhabditis elegans"

Jnos Kovcs, Attila L Kovcs, Tibor Vellai, Zsolt Plfia, Krisztina Takcs-Vellai, Judit Fehr

[International Worm Meeting, 2005]

Cellular autophagy is a process for the degradation of cytoplasmic constituents in eukaryotic cells. Since its discovery in 1957 in the epithelial cells of kidney of the newborn mice (1) electron microscopy has been and still remains an indispensable method for studying autophagy. One of the main reasons of the late start of autophagy research in C. elegans is the relative difficulty of performing transmission electron microscopy with worm samples. Recently we have developed a technique by which autophagic processes of the worm become accessible for systematic morphological and, in three major tissue types, for morphometric analysis by transmission electron microscopy (2). Our poster introduces the method, presents the criteria for the identification and morphological analysis of various types of autophagic vacuoles in all major cell types, and shows the latest morphometric data on autophagy in hypodermal, gut epithelial and body wall muscle cells during postembryonic development including all four larval, as well as the predauer, dauer and postdauer stages. Our results indicate that the cells of continuously feeding worms are practically devoid of autophagic vacuoles. Significant increase in the quantity of autophagic vacuoles can be observed at the end of each larval stage when the lethargus is reactivated. Systematic measurements on Daf-c mutants in the predauer period show that preparation for the dauer stage does not involve constitutive autophagic activity. (1) Clark S.L. (1957) Cellular differentiation in the kidneys of newborn mice studied with the electron microscope, J. Biophysic. Biochem. Cytol. 3, 349 (2) Kovacs AL, Vellai T, Muller F (2004) Autophagy in Caenorhabditis elegans. In: "Autophagy" Ed. Daniel J. Klionsky, Landes Bioscience 2004, Chapter 17, pp 216-223

Raymond C Chan et al. (2002) West Coast Worm Meeting "The C. elegans TIMELESS homolog is an essential regulator of chromosome cohesion."

Mili Jeon, Tammy F Wu, Raymond C Chan, Barbara J Meyer, Annette Chan, Ann Rougvie

[West Coast Worm Meeting, 2002]

Faithful segregation of chromosomes during cell division is essential for the inheritance of equivalent genetic information by each daughter cell. One mechanism to ensure the fidelity of chromosome segregation during mitosis is to maintain the tight association of sister chromatids from DNA replication until chromatid separation at anaphase. A conserved mitosis-specific multimeric protein complex, termed cohesin, is largely responsible for maintaining sister chromatid cohesion. The core of this complex consists of a heterodimer of Smc1 (structural maintenance of chromosome) and Smc3. At least two additional proteins are found within this complex; these include the Scc3p/SA (stromal antigen) and Scc1p/Mcd1p/RAD21 protein families. In meiosis, chromosomes undergo two rounds of division following a single round of replication in order to generate haploid gamates. To accommodate this specialized and highly regulated dispersal of meiotic chromosomes, there is also a meiosis-specific cohesin complex. A conserved difference between the mitotic and meiotic cohesin complexes is the substitution of the mitotic Scc1p/RAD21 protein by the meiotic REC-8 protein. Although the worm Scc1p homologs and their meiotic ortholog have been identified, the larger cohesin complexes, as defined by the four cohesin proteins, had not been fully characterized. Here we report the characterization of the mitotic and meiotic cohesin complexes in order to examine 1) the composition of the worm complexes relative to their counterparts in other eukaryotes and 2) the regulated localization of these proteins to meiotic chromosomes.

Kimura, Yoshishige et al. (2017) International Worm Meeting "Imaging mass spectrometry for C. elegans."

Kaneko, Tomomi, Aoyagi, Satoka, Kimura, Yoshishige

[International Worm Meeting, 2017]

Imaging mass spectrometry (IMS) is a two-dimensional mass spectrometry to visualize the spatial distribution of biomolecules, which does not need either separation or purification of target molecules. The free-living soil nematode C. elegans is a common model organism, extensively used in life science research. Though, various investigations have been performed for metabolomic profiling of worms, the information of a single worm has been lost by? the conventional mass spectrometry (MS) techniques. Thus, the development of a label-free, non-targeted MS technique for molecular mapping in C. elegans has been required. We have previously performed MALDI imaging of C. elegans. However, the resolution was not enough to analyze cellular or subcellular level of biomoleculer distribution. Thus, we next tried the application of TOF-SIMS (Time-of-Flight Secondary Mass Spectrometry) system for C. elegans, which enables us to obtain subcellular distribution of metabolites. By comparison of several sample preparation methods, the frozen sections of C. elegans fixed by paraformaldehyde (PFA) were suitable for TOF-SIMS analysis. By sputtering of Ar gas cluster ion beam (Ar-GCIB), the sensitivity to fatty acids (e.g. stearic acid (SA), oleic acid (OA), and eicosapentaenoic acid (EPA)) was significantly enhanced, and high-resolution images of biomolecules were acquired. Further modification to prepare C. elegans samples for TOF-SIMS imaging is in progress. This is promising to obtain the cellular and subcellular distributions of the various biomolecules easily and efficiently.

Ashe A et al. (2010) Aging, Metabolism, Stress, Pathogenesis, and Small RNAs, Madison, WI "Small RNAs With Characteristics Of 22Gs Are Present Multiple Generations After dsRNA Induced Silencing"

Ashe A, Goldstein L D, Miska E A, Lehrbach N J

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

Since the discovery of RNAi in C. elegans in 1998, our knowledge of the complexity of small RNA pathways in this organism has grown rapidly. We now know that there are many exogenous and endogenous small RNA pathways interacting in complex ways within the organism. Much of this knowledge has come about through advances in sequencing technology that allow us to see in great detail the numerous small RNAs present in cells. Despite this abundance of data, there are still many aspects of small RNA biology that remain unclear. From the first reports of gene silencing induced by exogenous dsRNA, it has been observed that the silencing can be heritable (1). For RNAi of most genes, silencing of the target gene is limited to the F1 generation, with subsequent generations reverting back to normal levels of gene expression. However, there are a small number of reported cases where silencing of a specific gene can be transmitted across multiple generations (2, 3, 4). The mechanism of inheritance is unknown, but studies have suggested the involvement of a diffusible element (4), or chromatin modifiers (3). Here we show that silencing of a single-copy GFP transgene can be inherited for multiple generations, and that this silencing correlates with the presence of small RNAs targeted to the transgene. 1. H. Tabara, A. Grishok, C. Mello, Science 282, 430-431 (1998) 2. A. Grishok, H. Tabara, C. Mello, Science 287, 2494-2497 (2000) 3. N. Vastenhouw, K. Brunschwig, K. Okihara, F. Muller, M. Tijsterman, R. Plasterk, Nature, 442, 882 (2006) 4. R. Alcazar, R. Lin, A. Fire, Genetics, 180, 1275-1288 (2008)

Orbidans, Helen E. et al. (2013) International Worm Meeting "Widespread pleiotropic Bateson-Dobzhansky-Muller incompatibilities between C. elegans isolates."

Snoek, L. Basten, Orbidans, Helen E., Harvey, Simon C., Stastna, Jana, Kammenga, Jan E.

[International Worm Meeting, 2013]

Bateson-Dobzhansky-Muller (BDM) incompatibilities are a result of deleterious interactions between alleles that are neutral or advantageous in their own genetic backgrounds. Both outbreeding depression and a specific incompatibility causing embryonic lethality have been identified within C. elegans. We therefore hypothesised that alleles producing BDM incompatibilities would also be present. Identifying the underlying loci producing such negative epistatic effects within a species is important as it will allow comparison to the loci and alleles that generate isolation between species, i.e. it addresses the role of BDM incompatibilities in driving speciation. To identify genomic regions showing BDM incompatibilities we undertook screens for regions that disrupted the normal process of egg-laying, a complex, highly regulated and coordinated phenotype. Screens were undertaken in recombinant inbred lines (RILs) and a genome-wide panel of nearly isogenic lines (NILs) both produced from the isolates CB4856 and N2. These RIL and NIL analyses identify a number of quantitative trait loci (QTLs) that show synthetic effects on egg-laying, i.e. the disruption in egg-laying is not seen in the parental isolates and is a consequence of negative interactions between CB4856 and N2 alleles. Analysis of these QTLs shows that they also affect other life history traits, affecting lifespan and the internal hatching of progeny (bagging). Further analysis indicates that this approach identifies only a subset of the incompatibilities between CB4856 and N2, that these incompatibilities are a consequence of complex interactions between multiple loci, and that they interact with the stress response. LBS and JK were funded by NWO-ALW NEMADAPT (project 855.01.151) and the Graduate School Production Ecology & Resource Conservation.

Susoy, Vladislav et al. (2014) Evolutionary Biology of Caenorhabditis and Other Nematodes "EVOLUTIONARY DIVERSIFICATION THROUGH THE GAIN AND LOSS OF DEVELOPMENTAL PLASTICITY"

Ragsdale, Erik J., Sommer, Ralf J., Susoy, Vladislav

[Evolutionary Biology of Caenorhabditis and Other Nematodes, 2014]

Developmental plasticity is common among plants and animals, yet its role in mediating evolutionary processes is debated. Several species of Rhabditina, including Pristionchus pacificus, can execute two alternative mouth phenotypes, one of which is associated with predatory feeding. Studies in P. pacificus have revealed that environmental factors act through a conserved genetic pathway that enables a rapid developmental response to the environment (Bento et al., 2010). In addition, a developmental switch that controls the expression of the alternative mouth phenotypes was recently identified (Ragsdale et al., 2013). In contrast, little is known about the macroevolutionary potential of the mouth plasticity. We studied the relationship between plasticity and morphological change by a macroevolutionary analysis of nematode mouthparts when accompanied by a dimorphism. To test whether plasticity facilitates or hinders morphological change, we analyzed variation in form and complexity in 90 nematode species with or without a mouth dimorphism. Our analyses revealed a two-step process of morphological diversification associated with the gain and loss of plasticity. First, acquisition of a dimorphism was accompanied by an increase in complexity, including structural innovations such as moveable teeth. Second, the fixation of a single mouth-phenotype in several nematode lineages was associated with a decrease in mouth complexity but a sharp increase in evolutionary rates when measured as change of shape and size. Thus, plasticity facilitates phenotypic diversification by fostering evolutionary novelties, whereas subsequent loss of the dimorphism enables acceleration of evolution by releasing novel morphologies from developmental constraints. 1. G. Bento, A. Ogawa, R. J. Sommer. Nature 466, 494-497 (2010). 2. E. J. Ragsdale, M. R. Muller, C. Rodelsperger, R. J. Sommer, Cell 155, 922-933 (2013).

Sym M et al. (2000) West Coast Worm Meeting "Two new genes regulating neuroblast migration in C. elegans"

Kenyon CJ, Sym M, Ch'ng Q-L, Yang L

[West Coast Worm Meeting, 2000]

In C. elegans, the Q cells are bilaterally symmetric neuroblasts present in the posterior body region of the worm at hatching. During the first larval stage, the Q cells divide and migrate. QR and its descendents migrate anteriorly whereas QL and its descendents migrate posteriorly. Several genes that regulate the anterior migrations of QR and its descendents have been identified. These include: 1) lin-39, a homeobox gene required in QR and its descendents for migration (Wang B. et al, 1993; Clark S. et al, 1993); 2) mig-13, a novel transmembrane protein required outside of QR and its descendents for migration (Sym M et al, 1999); and 3) egl-20, a Wnt homolog expressed in cells in the tail region (Whangbo J.. and Kenyon C, 1999). Two mutant screens (Mary Sym and Queelim Ch'ng) were conducted to identify additional genes that regulate the migration of QR and its descendents. From these screens, mutations in two new genes were identified that cause certain cells in the QR lineage to stop migrating prematurely. These two genes seem likely to be involved in guidance rather than in providing cells with the ability to migrate because, in these mutants, other cells sometimes migrate in the wrong direction. Current efforts are directed toward cloning these two genes and determining how these genes regulate the migration of QR and its descendents together with genes previously known to regulate these migrations. References: Clark SG, Chisholm AD, and Horvitz HR. 1993. Control of Cell Fates in the Central Body Region of C. elegans by the Homeobox Gene lin-39. Cell 74: 43-55. Sym M, Robinson N, Kenyon C. 1999. mig-13 Positions Migrating Cells Along Anteroposterior Body Axis of C. elegans. Cell 98: 26-36. Wang BB, Muller-Immergluck MM, Austin, J, Robinson, NT, Chisholm, A, Kenyon, C. A Homeotic Gene Cluster Patterns the Anteroposterior Body Axis of C.. elegans. Cell 74: 29-42. Whangbo J, Kenyon, C. A Wnt Signaling System that Specifies Two Patterns of Cell Migration in C. elegans. Molecular Cell 4: 851-858.