Gautam Kao et al. (2006) European Worm Meeting "The ATPase ASNA-1 Positively Regulates Insulin Secretion in C. elegans and Mammals and Promotes Growth Non-autonomously"

Simon Tuck, Gautam Kao, Maria Still, Peter Naredia, Cecilia Nordensson, Agneta Rannlund

[European Worm Meeting, 2006]

Gautam Kao1, Cecilia Nordensson2, Maria Still2, Agneta Rnnlund1, Peter Naredi2 & Simon Tuck1. C. elegans embryos that hatch in the absence of food arrest growth during the first larval stage (L1). While much has been learned about the later diapause, called dauer that worms enter on encountering adverse conditions little is known presently about the mechanisms governing L1 arrest. We have identified and characterized a gene, asna-1, which when mutated, causes a complete but reversible arrest at the L1 stage even in the presence of food. We find that asna-1 encodes an ATPase that functions non-autonomously to regulate larval growth. asna-1 is expressed in a restricted set of sensory neurons and in the intestine; cells that produce insulin. asna-1 mutants have reduced insulin signaling while overexpression of asna-1 mimics the effects of overexpressing insulin. The human homologue ASNA1, which rescues the C. elegans mutant phenotype, is expressed at high levels in human pancreatic ?eta cells but not in other pancreatic endocrine or exocrine cell types. Increase or decrease of ASNA1 function in mouse insulinoma cells causes an increase or decrease in insulin secretion respectively. Similarly, reducing asna-1 gene function in C. elegans causes a decrease in levels of secreted insulin. We propose that ASNA1 is a novel evolutionarily conserved modulator of insulin signaling.

Gautam Kao et al. (2006) Development & Evolution Meeting "The ATPase ASNA-1 Positively Regulates Insulin Secretion in C. elegans and Mammals and Promotes Growth Non-autonomously"

Maria Still, Cecilia Nordensson, Peter Naredi, Gautam Kao, Agneta Ronnlund, Simon Tuck

[Development & Evolution Meeting, 2006]

C. elegans embryos that hatch in the absence of food arrest growth during the first larval stage (L1). While much has been learned about the later diapause, called dauer, that worms enter on encountering adverse conditions, little is known presently about the mechanisms governing L1 arrest. We have identified and characterized a gene, asna-1, which when mutated, causes a complete but reversible arrest at the L1 stage even in the presence of food. We find that asna-1 encodes an ATPase that functions non-autonomously to regulate larval growth. asna-1 is expressed in a restricted set of sensory neurons and in the intestine; cells that produce insulin-like proteins. asna-1 mutants have reduced insulin/IGF-1 signalling (IIS) while overexpression of asna-1 mimics the effects of overexpressing worm insulin-like proteins. The human homologue, ASNA1, which rescues the C. elegans mutant phenotype, is expressed at high levels in human pancreatic beta cells but not in other pancreatic endocrine or exocrine cell types. Increase or decrease of ASNA1 function in mouse insulinoma cells causes an increase or decrease in insulin secretion respectively. Similarly, reducing asna-1 gene function in C. elegans causes a decrease in the secreted levels of the insulin-like protein daf-28. We propose that ASNA1 is a novel evolutionarily conserved modulator of insulin signalling.

Marta Maria Gaglia et al. (2006) European Worm Meeting "Transcriptional Changes Underlying Chemosensory Regulation of Lifespan"

Cynthia Kenyon, Marta Maria Gaglia

[European Worm Meeting, 2006]

Marta Maria Gaglia and Cynthia Kenyon. Mutations in the insulin/IGF-1-like receptor daf-2 alone can double the lifespan of C.elegans, suggesting that aging is not just a default state, but instead a genetically regulated process. However, it is not clear what physiological processes regulate the daf-2 pathway. Interestingly, mutants with altered chemosensation also have an extended lifespan (Apfeld and Kenyon, 1999). Both daf-2 and chemosensory mutant longevity are dependent on the activity of the FOXO transcription factor DAF-16. This suggests that external inputs through the chemosensory system may regulate the insulin pathway and in turn affect lifespan. Further studies have identified some of the cellular components of the sensory pathway of lifespan control (Alcedo and Kenyon, 2004). However, the molecular mechanism by which the chemosensory system modulates lifespan remains still largely unknown. To begin to elucidate the mechanisms of chemosensory regulation of lifespan, we have performed genome-wide expression analysis with microarrays on the long-lived chemosensory mutant daf-10. We are in the process of characterizing the genes whose expression was altered with mutants and RNA interference in sensitized backgrounds. In particular, we are interested in those genes that affect lifespan without causing a chemosensory defect, as they may act downstream of the sensory neurons. In addition we are comparing the expression changes to those occurring in daf-2 mutants, to determine how the two pathways interact to modulate lifespan.

Ralf Schnabel et al. (2002) European Worm Meeting "Improvement of the biolistic transformation of C. elegans"

Cathrin Struck, Ralf Schnabel

[European Worm Meeting, 2002]

Transformation of the worm by microinjection is now a rate-limiting step in many labs during the analysis of genes. We find microinjection still quite unreliable and cumbersome. At least in our hands the transformation rate is in average quite low, we get only one stable array per 30 injected hermaphrodites. In 1999 we demonstrated that the worm can be reliably transformed using ballistic bombardment with gold particles using a helium gun. However, the efficiency by which stable arrays were formed was still rather low, approximately one stable line per ten shots was isolated. Meanwhile we improved the method by a factor of 100; typically we now isolate 10 stable arrays per shot. One or two of these lines show a stable transmission of the transformed DNA, indicating that integration into the genome occurred. The in and outs of biolistic transformation will be discussed.

Mark T Palfreyman et al. (2002) West Coast Worm Meeting "The role of SNAREs in exocytosis"

Mark T Palfreyman, M Wayne Davis, Rob Weimer, Erik M Jorgensen

[West Coast Worm Meeting, 2002]

Neurotransmission at a chemical synapse occurs via the controlled fusion of synaptic vesicles with the plasma membrane. Central players in this process are the SNARE proteins. In C. elegans the SNARE proteins are encoded by unc-64, snb-1 , and ric-4 which correspond to syntaxin, synaptobrevin, and SNAP-25 respectively. Due to their central and conserved role in membrane fusion, the SNARE proteins have been widely studied. Yet despite extensive study, heated debate still remains concerning their function.

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.

Fujita, T. et al. (2019) International Worm Meeting "Identification of novel autophagy negative regulator modulating C. elegans reproductive lifespan."

Yoshimori, T., Fujita, T., Nakamura, S., Hamasaki, M., Kubo, S., Ogawa, H.

[International Worm Meeting, 2019]

In many species reproductive capacity is negatively correlated with animal lifespan. How the balance between these two is regulated is still unclear. The knowledge regarding the factors or processes specifically regulating reproductive capacity are still limited. So far it has been shown that TGF-b Sma/Mab signaling pathway non-cell autonomously regulates reproductive lifespan (Luo et al., Cell, 2010) but the gonad intrinsic factor is not poorly characterized. By using siRNA based screening in mammalian cell culture we identified novel nuclear protein, which negatively regulates an evolutionally conserved cytoplasmic degradation process, autophagy. Knockdown of the protein function induced autophagy via transcriptional upregulation of some autophagy related genes. The expression study of C. elegans homologs revealed that this nuclear protein is highly expressed in germline and/ or somatic gonadal cells including distal tip cells and sheath cells. Moreover, knockdown of these protein function significantly extended reproductive lifespan in an autophagy dependent manner, but not extended animal lifespan. These results indicate that this novel autophagy negative regulators uncouple the balance between reproduction and animal lifespan and thus are key factors to elucidate the underlying mechanism. We would like to discuss the possible mechanisms with our updated data.

Chen, W.-L. et al. (2019) International Worm Meeting "Dopamine-Mediated Gravitaxis in Caenorhabditis elegans."

Bau, H. H., Raizen, D., Chen, W.-L., Chuang, H.-S., Ko, H.-T.

[International Worm Meeting, 2019]

Molecular and circuit-based mechanisms that allow animals to sense and respond to gravity are still not clear. We found that well-nourished as well as starved wild-type N2 and AB1 adults suspended in aqueous solutions orient with the direction of the gravity vector and swim with their nose facing downwards. Paralyzed worms settle with a random orientation, indicating that nonuniform mass distribution is unlikely to cause gravitaxis behavior. In an aqueous solution that is slightly denser than the worms, worms still rotate to swim in the downwards direction, indicating that gravitaxis is not explained by hydrodynamic effects. Che-2 and osm-6 mutants, which have disrupted sensory cilia, show defective gravitaxis, suggesting that sensing gravity is mediated by sensory neurons. Cat-2 mutants, which have reduced dopamine, are gravitaxis defective, but show restored gravitaxis when dopamine is repleted pharmacologically. The mec-4 gene is not required for gravitaxis, suggesting that other mechanically responsive ion channels mediate the response to gravity. We establish C. elegans as a genetic system to study the sensation and response to gravity and conclude that gravity sensing requires ciliated neurons and dopamine.

Alcantara, Alfredo Jr. et al. (2019) International Worm Meeting "Investigating the Effects of Microgravity on the Neuromuscular Junction in C. elegans."

Alcantara, Alfredo Jr., Kalichamy, Saraswathi, Lee, Jin I., Moon, Je-Hyun, Higashitani, Atsushi

[International Worm Meeting, 2019]

A move towards deep space is on the horizon for humanity. Life, however, is adapted for earth not space gravity. Astronauts are known to experience muscle atrophy after a long-term stay in outer space, yet its complete effect on neuronal development and synaptic connectivity are still unclear. In our previous study, we demonstrated that hypergravity can affect axonal development of the DD/VD motor neuron in C. elegans. In this study, we wanted to know whether long-term altered gravity exposure can affect synaptogenesis in C. elegans GABAergic motor neurons. By using a snb-1::GFP reporter strain, we will expose the worms to various gravity conditions and observe the quality and quantity of the synaptic puncta formed. In addition, we are looking into other neuronal and cell biology effects of microgravity. We are currently conducting experiments in hypergravity using a centrifuge and simulated microgravity using a 2D and 3D clinostat. Furthermore, we have already sent our samples in outer space aboard the International Space Station (ISS) for actual microgravity exposure. Preparations to recover and analyze these samples are still on-going this year. We hope to reveal any effects of altered gravity in C. elegans synapse and likewise establish a good model for neuromuscular junction development in humans.

Branda CS et al. (1996) East Coast Worm Meeting "A Genetic Screen in an unc-53 Background Should Identify Components of the Gonad-Dependent Mechanism of Sex-Myoblast Migration in C. elegans"

Branda CS, Stern MJ

[East Coast Worm Meeting, 1996]

During larval development in C. elegans hermaphrodites, two sex myoblasts (SMs) are generated in the posterior of the animal. The SMs migrate anteriorly to final positions flanking the precise center of the developing gonad where they divide and differentiate to form the egg-laying muscles. While the gonad is required for their precise localization, the SMs are still able to migrate in the absence of the gonad to a broad range of positions spanning the center of the animal. Thus, two mechanisms are normally involved in the positioning of the SMs: a gonad-dependent mechanism and a gonad-independent mechanism. Only when both mechanisms are compromised do the SMs fail to migrate and remain essentially where they are generated. This redundancy prohibits the isolation of mutants that compromise only one mechanism Through the analysis of mutations that enhance the weak SM defects of sem-5 mutants, we discovered that mutations in unc-53 compromise the gonad-independent mechanism (Chen, et. al., submitted). While in unc-53 single mutants the SMs are still able to acquire their normal final positions, gonad ablation leads to severely displaced SMs. Thus, by compromising the gonad-independent mechanism, mutations in unc-53 make the migrations of the SMs completely dependent upon the gonad-dependent mechanism. This finding should allow us to use an unc-53 background to screen for mutations affecting the gonad-dependent mechanism. Based on this model, we postulate that sem-5 and let-60 are required for the gonad-dependent mechanism. While mutations in sem-5 and let-60 confer only weak SM migration defects on their own, in an unc-53 background they confer severe SM displacement. To identify other genetic components of the gonad-dependent mechanism, we are beginning to screen mutagenized unc-53 animals for mutants with severely displaced sex muscles. When the SMs are posteriorly displaced, the sex muscles are still generated but at posterior positions. We have integrated an egl-15::GFP reporter construct that is strongly expressed in the sex muscles to facilitate this screen.