Wang Y et al. (1998) East Coast Worm Meeting "JAK/STAT Signaling Pathway in C. elegans?"

Levy DE, Wang Y

[East Coast Worm Meeting, 1998]

The primary interest of our laboratory is to study JAK/STAT signaling pathway in mice. Though characterized by simplicity and directness in mammalian systems, this pathway is involved in many different regulatory events, such as innate immune responses to viral or bacterial infection, T cell functions, and embryonic development. In Drosophila, a STAT homologue has been identified and shown to be essential for embryonic development. The fact that Dictyostelium discoideum has a STAT-like molecule to regulate its pre-stalk cell differentiation suggests the existence of STAT(s) in a wide variety of organisms. We intend to identify JAK/STAT signaling pathway in C. elegans by cloning worm STAT(s) and use the genetic tools available in nematodes to characterize its role in development.

Wang, Y. et al. (2019) International Worm Meeting "Natural variation of C. elegans short tandem repeats."

Wang, Y., Andersen, E., Zdraljevic, S., Cook, D.

[International Worm Meeting, 2019]

Short tandem repeats (STRs) can rapidly evolve and have been implicated in the regulation of gene expression, genetic diseases, and complex traits. Despite the increased recognition of their functional importance, little is known about the variation of STRs across the Caenorhabditis elegansspecies. To understand how STRs evolve across the C. elegans population, we analyzed whole-genome sequencing data of 330 wild isolates and leveraged HipSTRs to infer the genetic variation of STRs. First, we identified 11,193 high-confidence polymorphic STRs, which are unevenly distributed across the genome. Second, we determined the allele frequencies of STRs across the population and found STRs that fall into coding regions show features of functional constraint, depleted heterozygosity, and increased interrupted allele frequencies. Third, we analyzed the distribution of STR motifs across the genome. We characterized motif-specific enrichment and depletion among the intergenic region, promoter, coding sequences (CDS), intron, and UTRs. Taken together, we discovered a large number of population-wide STR polymorphisms, of which variation could be shaped by natural selection in a motif-specific manner.

Wang, Y. et al. (2019) International Worm Meeting "Flexible motor sequence generation during stereotyped escape responses."

Zhen, M., Zhang, X., Xu, T., Huo, J., Wen, Q., Xin, Q., Xie, Y., Hung, W., Alkema, M., Wang, Y.

[International Worm Meeting, 2019]

Rich and organized animal behaviors arise from a flexible combination of stereotyped motor primitives. How do nervous systems generate interesting dynamics to purposefully explore the action space? Here we study escape responses of the nematode C. elegans, who predictably moves away from a potential threat, such as a mechanical or thermal stimulus. However, the motor sequences and the timing that constitute the whole behavior are variable. Our combined imaging, optogenetic and computational analyses suggest that a rapid feedforward pathway embedded in a stochastic recurrent attractor network underlies robust motor sequence generation, whereas functionally segregated neurons exploit synaptic inhibition with short-term depression to flexibly control motor state transitions. The worm connectome and molecular genetics also reveal that the feedforward coupling takes the form of electrical synapses while glutamatergic synaptic transmission contributes to selective inhibitions between motor programs. Behavioral statistics can be understood through computing the first passage time from the Fokker-Planck equation. Our results identify a neural computation for robust and flexible motor sequence generation in a compact nervous system.

Wang Y et al. (2010) Biology of the C. elegans Male, Madison, WI "Progress Towards A Reconstruction Of The C. elegans Male Anterior Nervous System"

Bloniarz A, Xu M, Wang Y, Hall D, Emmons S, Nguyen K

[Biology of the C. elegans Male, Madison, WI, 2010]

Having completed the connectivity of the posterior nervous system of the C. elegans male, we are now pursuing reconstruction of the C. elegans male head. Unlike the posterior nervous system, which contains 85 male-specific neurons, 55 common neurons whose cell bodies are in the posterior and 18 processes of common neurons running into the tail from the anterior, the head is occupied by 200 common neurons and four male-specific neurons as well as 4 processes of male-specific neurons running through from the posterior to the anterior. Our present connectivity results demonstrated that some common neurons have sexually dimorphic wiring. They establish input and output synapses with male-specific neurons in the tail and also may be connected differently to each other. Therefore, we suppose that common neurons in the head may also display different wiring in the male compared to the hermaphrodite. Male-specific neuron processes which run into the head will establish further differences. In addition to copulation, male behavior differs from that of the hermaphrodite in several general ways, such as locomotion, chemotaxis, and attraction to food and mates. To compare male connectivity in the head to that of the hermaphrodite, we have begun to collect EM images of the male head. We chose males which were capable of mating and used traditional methods to fix and section them. We have 5000 serial sections of three animals' heads. We are collecting EM data from two available electron microscopes in Albert Einstein College of Medicine. Digital images are computationally aligned (see abstract by Xu et al) and neurons are traced using our reconstruction platform Elegance. If everything is on schedule, we can reconstruct the C. elegans male head within this year.

Wang Y et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "Knock-out of Glial DEG/ENaC Channel ACD-1 Results in Sensory Deficits in a Hypomorphic Mutant of the cGMP Channel Subunit tax-2"

Wang Y, D'Urso G, Bianchi L

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

DEG/ENaC channels are voltage-independent Na+ or Na+/Ca2+ channels expressed in a large variety of tissues and mediate a wide range of physiological functions, including sensory perception and transepithelial Na+ transport, which is often coupled to K+ excretion. In the mammalian nervous system DEG/ENaCs are expressed both in neurons and glia. ASIC2 is expressed in the nerve fiber and core lamellae of the Pacinian corpuscles, whereas ASIC1a is expressed in brain neurons and astrocytes. However, the role of glial versus neuronal DEG/ENaC channels in the nervous system remains unclear. We recently reported the cloning and characterization of a novel DEG/ENaC channel in C. elegans termed ACD-1. ACD-1 is expressed in C. elegans glial amphid sheath cells but not in sensory neurons. ACD-1 activity is required with neuronal DEG/ENaC DEG-1 channel to mediate acid avoidance and attraction to lysine. Based on the unique phenotype of deg-1;acd-1 double mutant C. elegans, we hypothesized that ACD-1 is required for optimal neuronal function and that knock-out of function may exacerbate sensory deficits caused by mutations in sensory neurons genes. We report here that knock-out of acd-1 in glia exacerbates and results in sensory deficits caused by a hypomorphic allele of the cGMP gated channel subunit tax-2 (tax-2(p694)). The sensory deficits of tax-2(p694);acd-1 double mutant C. elegans include the inability of sensory neurons to respond to sensory cues, but does not result in defects in the downstream interneurons. The sensory deficits caused by mutations in other signaling genes including Gi protein odr-3 and guanylate cyclase daf-11, are not exacerbated by knock-out of acd-1. Finally, the sensory deficits caused by knock-out of acd-1 are consistent with the hyperpolarization of the plasma membrane of the sensory neurons. We propose that ACD-1 in glia may regulate the function of sensory neurons by controlling their resting potential, perhaps through control of the extracellular K+ concentration.

Y Wang et al. (1999) International C. elegans Meeting "Molecular Cloning and Characterization of a STAT homologue in C. elegans"

DE Levy, Y Wang

[International C. elegans Meeting, 1999]

Though characterized by simplicity and directness in mammalian systems, JAK/STAT signaling pathway is involved in many different regulatory events, such as innate immune responses to viral or bacterial infection, T cell functions, and embryonic development. In Drosophila , a STAT homologue has been identified and shown to be essential for embryonic development. The fact that Dictyostelium discoideum has a STAT-like molecule to regulate its pre-stalk cell differentiation suggests the existence of STAT(s) in a wide variety of organisms. Here we report a C. elegans homologue of STATs. Nucleotide sequence analysis reveals that the 2.4kb cDNA contains a single ORF about 2.1kb which encodes a 80KD protein. With human STAT5b, ceSTAT shares 29% identity in SH2 domain, 37% in DNA binding domain. It also contains a GYIQ tyrosine phosphorylation motif which is conserved in all the STATs. Surprisingly, ceSTAT does not have an N-terminal domain which is highly conserved in mammalian STATs as well as in Drosophila STAT. Northern analysis of total RNA from mix-staged N2 worms shows a single mRNA of 2.4kb. When expressed in cell culture, ceSTAT can be tyrosine phosphorylated by mammalian kinases, resulting in its ability to bind DNA probe containing GAS element. Further, the C-terminus contains a transactivation domain that will function when fused to the GAL4 DNA binding domain. Initial studies of the function of ceSTAT involved injection of dominant-inhibitory dsRNA. We saw no phenotype in either injected animals, F1 or F2 progeny. This suggests that ceSTAT is probably not involved in worm developmental processes. To further determine the function of ceSTAT, we are currently isolating mutagenized worms carrying genomic mutations.

Sato, Manami et al. (2015) International Worm Meeting "Expression pattern of C. elegans Y RNA homologs."

Ushida, Chisato, Kihara, Shinya, Sato, Manami

[International Worm Meeting, 2015]

Y RNA is a small structured ncRNA of about 100 nt in length. This RNA binds to Ro60 protein, which is a target of autoimmune disease antibody in patients with systemic lupus erythematosus and Sjogren's syndrome. Several lines of evidence suggest that the role of Y RNA and Ro60 function in the quality control of structured ncRNAs in cells under stress conditions. It is also indicated that vertebrate Y RNAs function in the initiation of DNA replication without Ro60. However, the molecular mechanisms of these functions and the contribution of Ro60/Y RNP to the autoimmune disease are still unclear. C. elegans genome encodes one Ro60 homolog (ROP-1) and 19 Y RNA homologs (1 CeY RNA and 18 sbRNAs). Other animals also have several Y RNA homologs, but C. elegans is the first example which has more than 5 Y RNA homologs encoded in the genome. Here we show the expression pattern and the cellular localization of these Y RNA homologs in C. elegans examined by the RNA fluorescent in situ hybridization (RNA-FISH). The signals of 14 homologs were detected in the intestinal cytoplasm. The signals of two other homologs were detected in the germ cytoplasm. The remaining three could not be detected, probably because they present in too low abundance to be detected by RNA-FISH. All 19 Y RNA homologs have the structural elements required for the binding of ROP-1. In other organisms, Ro60 binding stabilizes Y RNAs in cells. To know whether C. elegans Y RNA homologs also stabilized by the presence of ROP-1, we examined RNA-FISH of the Y RNA homologs against a mutant strain MQ470, which has a transposon insertion in the middle of the ROP-1 gene and lacks ROP-1 proteins in the cell. As expected, all Y RNAs examined so far decreased extensively. These were confirmed by northern hybridization. The results suggest that several C. elegans Y RNA homologs are expressed in a tissue-specific manner and most Y RNA homologs are stabilized by ROP-1 binding as well as those in other organisms.

Nancy L Price et al. (2003) International Worm Meeting "The utilization of Caenorhabditis briggsae as a host model to study bacterial pathogenesis"

Ann M Rose, Nancy L Price

[International Worm Meeting, 2003]

Caenorhabditis elegans has now been established as a host model for studies of infectivity by bacterial pathogens including Pseudomonas aeruginosa, Salmonella typhimurium, Burkholderia pseudomallei, and Enterococcus faecalis. However, virulence determinants of bacterial pathogens are regulated by temperature and environmental conditions, thereby limiting the use of C. elegans which cannot survive in temperatures higher than 25oC. This study shows that the related species, C. briggsae survives better than C. elegans on bacterial culture media at higher temperatures and describes the effects on C. briggsae of mammalian enteric pathogens, primarily Yersinia enterocolitica. C. briggsae grown on Y. enterocolitica accumulated bacteria in the gastrointestinal tract of the worm, resulting in decreased life-span and progeny fitness in a depleted-calcium environment. The mechanisms of the interaction are as yet unknown as both virulent and avirulent strains of Y. enterocolitica displayed the similar results. Investigations were undertaken to examine whether the shortened life span could be attributed to starvation, toxicity, or possible infection. Starvation effects was determined not to be the sole cause of pre-mature worm death as C. briggsae grown on Y. enterocolitica survived several days longer than starved worms. A bacterial mixing experiment using both Y. enterocolitica and E. coli OP50 shortened the worm life span compared to feeding on Y. enterocolitica alone, suggesting a possible toxic effect. However worms feeding on Y. enterocolitica and later shifted to E. coli OP50 resulted in reversion of the survival curve to that of worms feeding on E. coli OP50 alone, indicating that the detrimental effect of Y. enterocolitica was reversible. Fluorescent labeling of bacterial strains with a lacZ-GFP reporter gene demonstrated that Y. enterocolitica, but not E. coli OP50, is retained in the gut, a result which is compatible with a molecular interaction between Y. enterocolitica and nematode cellular components. These findings suggest that Y. enterocolitica may cause an infection within the nematode gastrointestinal tract and provide an assay for genetic dissection of the molecular basis of pathogenesis.

Michael Muller et al. (2006) European Worm Meeting "A Knock-Out of the Small Non-Coding Y RNA in C. elegans"

Michael Muller, Michael Jantsch, Gunter Steiner, Verena Jantsch

[European Worm Meeting, 2006]

Michael Mller1, Verena Jantsch2, Michael Jantsch2, Gnter Steiner1. Ro ribonucleoproteins (RNPs) are small cytoplasmic particles of unknown function that have been found in all eukaryotes except yeasts. The core structure of human Ro RNPs is composed of one molecule of Y RNA to which the 60 kD Ro protein (Ro60) and La protein are stably bound. Ro RNPs are predominant target structures in the autoimmune diseases Systemic Lupus Erythematosus and Sjgrens syndrome and autoantibodies to Ro60 and La, can be frequently found in the sera of patients suffering from these diseases. The Ro60 protein is highly conserved in higher eukaryotes and the phenotype of a disruption of the gene encoding the C. elegans Ro60 homologue (rop-1) was characterized (Labb et al. Genetics 1999, PNAS 2000). A decrease in Y RNA levels and a higher frequency of misfolded ribosome-associated 5s rRNAs was observed in rop-1 mutant worms. Rop-1 mutants were also shown to be defective in the formation of dauer larvae. Recently the structure of Ro60 was established (Stein et al. Cell 2005) and it was shown that the Y RNA binding site of Ro60 overlaps with the binding site for misfolded RNAs. These results suggest a regulatory role the Y RNA for the binding of misfolded RNAs to Ro60.. In humans and most other vertebrates four different Y RNAs are expressed, while in the nematode C. elegans only one Y RNA species has been found. The C. elegans Y RNA is highly conserved in its structure and most closely related to human Y3 RNA. Yet it differs from other eukaryotic Y RNAs as it is missing a 3 extension to which La is binding (van Horn et al. RNA 1995). To learn more about the function of Y RNAs, we took advantage of the fact that the C. elegans genome contains only a single Y RNA gene (yrn-1). We generated a knock-out line of the C. elegans Y RNA by the method of gene targeting by biolistic transformation. Yrn-1 is located within an intron of an uncharacterized, protein-coding gene. We modified a method for gene disruption (Berezikov et al. Nucleic Acids Res. 2004) in our approach, as we deleted yrn-1 in our knock-out construct rather than disrupting the locus, which could have resulted in a double knock-out.. Yrn-1 mutant worms do not display any obvious morphological phenotype. However, preliminary results indicate that Y RNA deficient worms show a delayed response to chemoattractants. Future experiments are planned to elucidate the role of the Y RNA in damage repair upon UV induced damage, in coping with various forms of stress and in the dauer formation pathway.

Sophie Jarriault et al. (2007) International Worm Meeting "The Y to PDA cell identity change in C. elegans : an in vivo model to study cell plasticity."

Yannick Schwab, Iva Greenwald, Sophie JARRIAULT

[International Worm Meeting, 2007]

The question of trans-differentiation or how a commited cell can change its identity has important implications ranging from organ regeneration to cancer. The lineage of the nematode C. elegans has identified a few cells that change their fates as the worm develops (1, 2), but this interesting observation has never been studied further. We are interested in understanding the molecular events underlying the Y to PDA cell transformation in C. elegans. Y is an epithelial cell that is part of the rectum in young larvae. It subsequentely moves anteriorly and becomes PDA, a motor-neuron which has a characteristic axonal projection . We have developed a set of useful molecular markers that allow to track the Y to PDA transformation and characterised the steps involved in this process, which we timed precisely with respect to the development of the somatic gonad. We have characterised the epithelial features of the Y cell at the ultrastructural level by electron-microscopy and we have examined the expression of cell fate markers in both cells. In addition, we showed that Y''s identity change does not require genes known to affect the developmental timing in C. elegans and we found that cell fusion, a possible mechanism invoked for trans-differentiation in vertebrates, does not contribute to the Y to PDA transformation. Finally, we have examined the importance of cell to cell interactions for the Y to PDA transformation by cell ablation experiments and studies of mutants affecting it, and what makes the Y cell competent to change its identity. We believe that this system is a powerful model to study cell plasticity in vivo, and we will discuss the results of our findings at the meeting. 1. J. E. Sulston, H. R. Horvitz, Dev Biol 56, 110-56 (Mar, 1977). 2. J. E. Sulston, J. G. White, Dev Biol 78, 577-97 (Aug, 1980).