Mains PE et al. (1989) International C. elegans Meeting "interacting maternal-effect mutations of C elegans."

Mains PE, Sulston IA, Wood WB

[International C. elegans Meeting, 1989]

Tao Cai et al. (2008) C.elegans Neuronal Development Meeting "Loss of the Transcriptional Repressor PAG-3 Results in Enhanced Neurosecretion that is Dependent on the Dense-Core Vesicle Membrane Protein IA-2"

Abner Notkins, Guofeng Zhang, Ping Yu, Michael Krause, Tetsunari Fukushige, Hiroki Hirai, Tao Cai

[C.elegans Neuronal Development Meeting, 2008]

It is generally accepted that neuroendocrine cells regulate dense core vesicle (DCV) biogenesis and cargo packaging in response to secretory demands, although the molecular mechanisms of this process are poorly understood. One factor that has previously been implicated in DCV regulation is IA-2, a catalytically inactive protein phosphatase present in DCV membranes. Our ability to visualize a functional GFP-tagged version of IA-2 directly in live C. elegans animals has allowed us to capitalize on the genetics of the system to screen for mutations that disrupt DCV regulation. We found that loss of activity in the transcription factor PAG-3, that functions as a repressor in many systems, results in a dramatic up-regulation of IA-2 and other DCV proteins. The up-regulation of DCV components was accompanied by an increase in presynaptic DCV numbers and resulted in phenotypes consistent with increased neuroendocrine secretion. Double mutant combinations revealed that these PAG-3 mutant phenotypes were dependent on wild type IA-2 function. Our results support a model in which IA-2 is a critical element in DCV regulation and reveal a novel genetic link to PAG-3-mediated transcriptional regulation.

Tao Cai et al. (2003) International Worm Meeting "IA-2, a Vesicle Membrane-Associated Protein, Regulates Synaptic Transmission in C. elegans"

Michael Krause, Tetsunari Fukushige, Tao Cai, Abner L Notkins

[International Worm Meeting, 2003]

IA-2, a major autoantigen in type 1 diabetes, is a receptor-tyrosine phosphatase-like protein associated with the membrane of secretory granules of neural and endocrine-specific cells. IA-2 lacks phosphatase activity due to an amino acid substitution within the catalytic domain and the function of IA-2 remains unclear. In order to gain insight into the cellular functions of IA-2, we have studied the C. elegans homolog, CeIA-2 encoded by the ida-1 gene. Using two independent, putative null, deletion alleles of ida-1 we show that animals lacking CeIA-2 are viable with only subtle visible phenotypes. Pharmacological studies show loss of CeIA-2 results in presynaptic neuronal defects involving neurotransmitter release. Furthermore, ida-1 interacts genetically with unc-31 and unc-64, two genes encoding factors required for neuronal vesicle function. These results suggest that CeIA-2 is a novel regulator of synaptic transmission that regulates vesicle release.

Hiroshi Ichijo et al. (2006) East Asia C. elegans Meeting "Analysis of mutants defective in olfactory learning induced by AWC-sensed odorants."

Hiroshi Ichijo, Kotaro Kimura, Ichiro Torayama, Isao Katsura

[East Asia C. elegans Meeting, 2006]

C.elegans changes its behavior based on its experience, which can be regarded as learning. For example, animals decrease the efficiency of taxis to a stimulus after they have received the same stimulus under starving conditions: Animals conditioned with starvation and NaCl no longer migrate toward NaCl, and the animals that had been starved at certain temperature avoid the starvation-temperature upon temperature gradient (Saeki et al., 2001; Mohri et al., 2005). In contrast, we discovered that conditioning with food and the AWC-sensed odorant butanone (Bu) enhances chemotaxis to this odorant, which we call butanone enhancement (Torayama et al., submitted).Recently we found that such olfactory enhancement was not specific to butanone: animals showed olfactory enhancement after conditioning with food and AWC-sensed odorant Isoamyl alcohol (Ia) or 2,3-pentanedione (Pd), although animals that conditioned with food and the AWC-sensed odorant benzaldehyde or the AWA-sensed odorant diacetyl exhibited almost no change or decrease (i.e., adaptation) rather than increase in the response to the same odorants.To elucidate the molecular mechanism of olfactory enhancement, we used a forward genetic approach. We screened 7000 genomes and isolated seven candidate mutants for the Ia olfactory enhancement (ut321 - ut327). We are analyzing the phenotypes of these mutants and other mutants that were previously isolated for the Bu olfactory enhancement defective (ut301-ut315). One of the Ia olfactory enhancement mutants (ut324) and some of the Bu olfactory enhancement mutants were also defective in the Pd olfactory enhancement. In this meeting, we will also report on the progress in the genetic mapping of ut324 and some other mutants.

Makoto Tsunozaki et al. (2002) West Coast Worm Meeting "Mechanisms of odor discrimination"

Makoto Tsunozaki, Cori Bargmann

[West Coast Worm Meeting, 2002]

We are using the chemotactic response to volatile odors by C. elegans to ask how animals discriminate between multiple inputs to produce the appropriate behavior. The AWC amphid neurons of C. elegans sense the attractive odors benzaldehyde (bz), butanone (bu), isoamyl alcohol (iaa), pentanedione (pd), and trimethylthiazole (tmt). The AWC pair alone can discriminate between bu, pd, tmt, and bz/ia - that is, in a uniform background of one odor, animals can still chemotax towards a point source of a different odor. The mechanisms for odor discrimination are not well understood.

Weber M et al. (2000) European Worm Meeting "Regulation of programmed cell death in the Germ line of C. elegans Hermaphrodites"

Conradt B, Weber M

[European Worm Meeting, 2000]

Four genes, egl-1 (for egg laying defective), ced-9 (for cell death defective), ced-4, and ced-3, form the general PCD (Programmed Cell Death) pathway in somatic tissues of C. elegans (METZSTEIN et al. 1998). Although ced-9, ced-4, and ced-3, are also involved in PCD in the germ line of hermaphrodites, the regulatory, proapoptotic egl-1 gene is not required for PCD in this tissue (CONRADT & HORVITZ 1998, GUMIENNY et al. Q999). This indicates that different pathways regulate the process of PCD in the soma and in the germ line. To identify loss-of-function mutations in proapoptotic genes acting specifically in the germ line, we are screening for mutants with reduced PCD in the germ line. To that end, the numbers of cell corpses in the germ line of the F2 progeny of EMS-treated animals are analyzed using Nomarski optics. The screen is performed in a ced-1 mutant background, in which the engulfment of germ cell corpses is partially blocked and in which cell corpses therefore accumulate in the germ line. The ced-1 mutant background hence increases the sensitivity of the screen and allows the identification of mutants with weak defects. The extend of PCD in the germ line of hermaphrodites increases with age (SULSTON 1988, GUMIENNY et al. 1999). In addition, it has been reported that the death of germ cells may be affected by environmental factors (SULSTON 1988). To determine whether PCD in the germ line varies with environmental conditions, and therefore might be regulated cell non-autonomously, we are in the process of examining the effect of stress and food-deprivation on PCD in the germ line. Conradt, B. and Horvitz, H. R. (1998). Cell 93, 9-529. Gumienny, T. L., Lambie, E., Hartwieg, E., Horvitz, H. R. and Hengartner, M. O. (1999). Development 126, 1011-1022. Metzstein, M. M., Stanfield, G. H. and Horvitz, H. R. (1998). Trends Genet., 14: 408-414. Sulston, J. (1988) in The Nematode Caenorhabditis elegans, (ed. W. B. Wood), pp. 123-155. Cold Spring Harbor.

Hiroshi Ichijo et al. (2007) International Worm Meeting "Genetic mapping of a novel butanone enhancement mutant."

Kotaro Kimura, Hiroshi Ichijo, Ichiro Torayama, Isao Katsura

[International Worm Meeting, 2007]

We have previously reported that C. elegans enhances its chemotaxis to butanone (bu) after conditioning with food and the odorant, which we call butanone enhancement. This behavioral plasticity is independent to serotonin, which is requires for the modulation of many other food related behavioral plasticity. Analysis of olrn-1(ut305) and olrn-2/bbs-8(ut306) (olrn: olfactory leaning defective) revealed that butanone enhancement is probably conducted in the STR-2-expressing AWC (AWCON) neuron and required the function of Bardet-Biedl syndrome genes, suggesting the importance of sensory cilia in this plasticity (Torayama et al., 2007). Such olfactory enhancement was not specific to butanone: animals also showed olfactory enhancement after conditioning with food and AWC-sensed odorants Isoamyl alcohol (Ia) or 2,3-pentanedione (Pd) (Ichijo et al., EAWM 2006). To elucidate the molecular mechanism of olfactory enhancement, we used a forward genetic approach. We screened 7000 genomes and isolated seven candidate mutants for the Ia olfactory enhancement (ut321 - ut327). We analyzed the phenotypes of these mutants and other mutants that were previously isolated as Bu olfactory enhancement defective mutants (ut301-ut315). Among these mutants, ut311 showed nearly normal chemotaxis to AWC-sensed odorants (Bu, Ia and Pd), and defects in Bu- and Pd-enhancement. To assess whether ut311 has defects in asymmetrical differentiation of AWC neurons and sensory cilia formation, we checked the expression pattern of str-2::gfp and the dye filling of sensory neurons with the fluorescence dye DiI in ut311. ut311 showed neither the 2 AWCOFF phenotype nor dye-filling defects. This suggests that the Bu enhancement defects in ut311 is due to a reason independent of the olrn-1 and olrn-2. To clone the responsible gene for ut311, we mapped ut311 to the 2.5 map unit interval on the chromosome V by snip-SNPs. In this meeting, we will report on the progress of detailed mapping and cloning of ut311.

Diya Banerjee et al. (2004) East Coast Worm Meeting "Molecular connections between developmental timing and circadian timing: The C. elegans homolog of the circadian gene doubletime regulates post-embryonic developmental timing"

Alvin Kwok, Shin-Yi Lin, Diya Banerjee, Frank Slack

[East Coast Worm Meeting, 2004]

Spatial patterning during animal development is genetically controlled by genes such as the Hox cluster. Similarly, the temporal aspect of developmental patterning is under the genetic control of heterochronic genes. The most extensively investigated heterochronic pathway defines a somatic clock that controls the timing of cell fate determination during C. elegans post-embryonic development. Although a number of key heterochronic genes have been identified, the molecular mechanisms that underlie temporal control of cell division and proliferation remain elusive. The heterochronic gene lin-42 is the C. elegans homolog of Drosophila and mammalian period , key regulators of circadian rhythms, which specify behavior and physiology over a 24 hour day/night cycle. lin-42 thus defines a molecular link between two different types of biological clocks: developmetal timing and circadian timing. In addition to lin-42 , the C. elegans genome contains homologs of a number of core circadian clock genes. We have investigated the possible function of these homologs in control of developmental timing by using RNA interference (RNAi) to knock-down gene expression. We describe the identification and characterization of two genes that interact with the developmental clock: kin-20 (casein kinase I e /CKI e ) and kin-19 (casein kinase I a/ CK Ia ), which are C. elegans homologs of Drosophila doubletime . kin-19 / CK Ia and kin-20/CKI e antagonistically regulate cell fate decisions during late larval development. kin-19 is downstream of and negatively regulated by kin-20 , lin-42, lin-41 and hbl-1, which either work together or in parallel. We have also found that the homologs to the Drosophila clock genes timeless , casein kinase II a , protein phosphatase 2A, vrille, and pdp1 appear to function in the developmental clock. Our results, showing function of multiple circadian gene homologs in the developmental clock, suggest that circadian and developmental timing pathways may utilize conserved mechanisms of temporal regulation. Our work also suggests that one or more of the heterochronic genes already identified, including CK Ia and microRNAs, may play a role in circadian timing. Furthermore, our findings point to circadian genes being regulators of cell fate timing, and support reports that circadian genes can function as oncogenes in mammals.

Morck, Catarina et al. (2011) International Worm Meeting "Soulless nematodes: KIN-29 mediates the essential function of the CAN neurons."

Garriga, Gian, Morck, Catarina

[International Worm Meeting, 2011]

The canal-associated neurons (CANL/R) are two bilaterally symmetric neurons that are born in the head and migrate to the middle of the embryo. Each neuron extends two processes: one process grows to the head and one to the tail (1). The CANs are essential for viability. Sulston and Hodgkin originally discovered that killing the CANs with laser microsurgery resulted in a starved appearance and larval arrest, leading them to propose that the CANs were the nematode soul (2). Similarly, ceh-10(gm58) mutants lack CANs and die as larvae (3). In vab-8(e1017) mutants, the CAN neurons fail to migrate, and their posterior processes only extend a short distance. As a consequence, the part of the body that lacks CAN processes becomes much thinner and the worms exhibit a withered tail phenotype (4). We identified a mutation that suppresses the withered tail phenotype of vab-8 mutants and the larval lethality of ceh-10 mutants. Surprisingly, the double mutants still retain defective CANs, which indicates that the suppressor mutation bypasses the requirement for CAN function. The suppressor encodes kin-29, a serine threonine kinase most homologous to members of the ELKL motif kinase (EMK) family and salt-induced kinase family (5). KIN-29 and its homologs phosphorylate and inhibit class II histone deacetylases. In C. elegans, KIN-29 inhibits HDA-4, which acts with the MADS domain transcription factor MEF-2 to regulate chemoreceptor gene expression (6). Loss of HDA-4 or MEF-2 is not lethal, indicating that KIN-29 must have other targets that mediate CAN function. The pseudocoelom fills with fluid in animals with compromised CAN function. This phenotype and the association of the CAN processes with the excretory canals led us to test the model where the CANs essential function is to regulate the activity of the excretory canals. The analysis of CAN and excretory canal mutants suggest that the CANs regulate other cells, and we are currently attempting to identify CAN target cells by addressing where KIN-29 functions. REFERENCES: 1.Sulston, J.E., E.Schierenberg, J.G. White and Thomson, J.N. (1983) Dev. Biol. 100: 64-119 2.Sulston, J.E. and Hodgkin, J.A. Worm Breeder's Gazette 5(1): 19 3.Forrester, W.C., Garriga, G. (1997) Development 124(9): 1831-43. 4.Manser, J. Wood, W.B. (1990) Dev Gen 11:49-64 5.Lanjuin, A., Sengupta, P. (2002) Neuron 33(3): 369-81 6.van der Linden, A.M., Nolan, K., Sengupta, P. (2007) EMBO. 26(2): 358-70.

Iwen Fu et al. (2004) East Coast Worm Meeting "Cloning and characterization of the C. elegans post-embryonic cytokinesis gene unc-85"

Iwen Fu, Fern P Finger, Jason W Reuter

[East Coast Worm Meeting, 2004]

Cytokinesis, the physical division of a mother cell into two daughter cells, is the final stage of the cell cycle. We are studying the unc-85 gene, which is required for post-embryonic cytokinesis in C. elegans. Consistent with its known role in post-embryonic cytokinesis (1, 2) , we find little lethality in unc-85(e1414) mutants during embryogenesis and larval development. The uncoordinated phenotype of unc-85(e1414) mutants has been attributed to cell division failures of post-embryonic ventral cord neuronal precursors (1, 2) . However, assays of locomotory behavior reveal that approximately 45% of newly hatched unc-85 mutants are uncoordinated. Because all of the embryonic ventral cord neurons are present, the uncoordination cannot be attributed to cytokinesis failures in the ventral cord neuronal precursors. This suggests an additional function for unc-85 in neuronal morphogenesis or function. We are cloning the unc-85 gene to determine its molecular identity. Its genetic location has previously been mapped to a 664 kb region on chromosome II between vab-1 and pho-1 . Using a combination of deficiency and snip-SNP mapping, we have narrowed the position of unc-85 to a 225 kb region between F59A6.3 and pho-1 , a region spanned by eight cosmids, and we are continuing to narrow the unc-85 region by additional SNP mapping. We will attempt to rescue unc-85(e1414) mutants by injection of cosmids, and we will also use RNAi to test candidate genes in the unc-85 region for unc-85(e1414) phenocopy. 1. Sulston, J. and Horvitz, H. Abnormal cell lineages in mutants of the nematode C. elegans . Dev. Biol., 82: 41-55, 1981. 2. White, J. G., Horvitz, H. R., and Sulston, J. E. Neurone differentiation in cell lineage mutants of Caenorhabditis elegans . Nature, 297: 584-587, 1982.