Toshiaki Suzuki et al. (2003) International Worm Meeting "Analysis of Ce-PARKIN in C. elegans"

Nobutaka Hattori, Toshiaki Suzuki, Keiji Tanaka, Yoshikuni Mizuno, Shohei MItani, Noriyuki Matsuda, Hideki Yashiroda, Toshiaki Kitami, Keiko Gengyo-Ando

[International Worm Meeting, 2003]

Autosomal recessive juvenile parkinsonism (AR-JP) is one of the most common forms of familial parkinsons disease characterized by selective loss of dopaminergic neurons in substantia nigra and the locus coeruleus. parkin is the causative gene of AR-JP. The human parkin gene encodes 465 amino acids with a ubiquitin-like domain in the amino-terminus and two RING finger motifs in the carboxy terminus. So far, various deletion mutations and point mutations have been discovered in patients of AR-JP, suggesting that the loss of function of Parkin is the cause of AR-JP. Recently we and others showed that Parkin has a ubiquitin-protein ligase activity and therefore suggested that the defect of protein degradation in the neurons of AR-JP patients (Shimura H. et al. Nat. Genet. 25, 302-5, 2000). To investigate the function of Parkin in vivo, we began to analyze the Ce-PARKIN of C. elegans. Two deletion mutations in parkin genes show no defect in their viabilities. The expression of Ce-PARKIN seems to be specific to subset of neurons. Therefore, we focused on the function of Ce-PARKIN in the neurons and the analysis is underway.

Aamna Kaul et al. (2003) International Worm Meeting "Hyperactivation of glutamate-gated chloride channels with ivermectin results in necrosis."

Joseph Dent, Aamna Kaul

[International Worm Meeting, 2003]

Ivermectin is a widely used antiparasitic drug. It kills worms by activating glutamate-gated chloride channels (GluCls), which belong to the family of ligand-gated anion channels that includes the GABA and glutamate receptors (Cully et al., 1994; Dent et al., 2000). The chloride permeability that ivermectin induces in excitable cells tends to prevent excitation. For example, ivermectin targets a GluCl expressed in the pharyngeal muscle to inhibit muscle contraction and prevent eating (Dent et al., 1997). The worms linger for several days in the presence of ivermectin before they starve to death. However, we have found that the lethal effects of ivermectin on C. elegans become irreversible after only a few hours of exposure. When L1 worms were exposed to 20ng/ml for 5 hours and then washed, they gradually developed large vacuoles in their pharyngeal muscle over the next several days. A mutant strain that lacks ivermectin receptors shows little or no necrosis when treated. Ivermectin is hydrophobic and it irreversibly opens GluCls expressed in Xenopus oocytes. So it is possible that ivermectin persists in membranes and continues to activate GluCls. Furthermore, it has been shown that hyperactive cation channels can induce excitotoxic necrosis (Driscoll and Chalfie, 1991). Why, though, would an inhibitory channel have a similar effect when hyperactivated? We are trying to address this question by looking at whether mutations known to inhibit excitotoxicity also inhibit the necrotic effects of ivermectin. Cully DF, Vassilatis DK, Liu KK, Paress PS, Van der Ploeg LHT, Schaeffer JM, Arena JP. Nature 371: 707-711 1994 Dent JA, Smith MM, Vassilatis DK, Avery L. PNAS USA 97: 2674-2679 2000 Dent JA, Davis MW, Avery L. EMBO Journal 16: 5867-5879 1997 Driscoll, M and Chalfie, M. Nature 349: 588-593 1991

Cully DF et al. (1993) International C. elegans Meeting "Expression cloning of an avermectin and glutamate-sensitive chloride channel from C. elegans."

Arena JP, Paress PS, Liu KK, Cully DF

[International C. elegans Meeting, 1993]

Banse, S.A. et al. (2017) International Worm Meeting "The Crucible: A microfluidic platform for stress assays."

Jarret, C.M., Blue, B.W., Robinson, K.J., Phillips, P.C., Banse, S.A.

[International Worm Meeting, 2017]

In a world of uncertainty, an organism's ability to mount a response to stress is fundamental to its interaction with the environment. Experimental exploration of that interaction benefits greatly from tight environmental control, as well as the ability to minimize the behavioral response of fleeing stress. We present a microfluidic platform that enables tight environmental control, and high-throughput image acquisition while confining single animals to individual arenas that allow a broad range of behavioral activities. The platform is easily scalable, with two 50 arena arrays per chip, and an imaging capacity of 600 animals per imaging scanner. We present validation of the stress platform using osmotic stress, oxidative stress, and starvation, although the system should be adaptable to many stress paradigms.

Gourgou, E. et al. (2019) International Worm Meeting "Can C. elegans learn to navigate in a maze? A story of food-triggered, touch-governed spatial learning."

Gourgou, E., Hsu, A-L, Cheh, C., Adiga, K., Goettemoeller, A.

[International Worm Meeting, 2019]

C. elegans ability to exhibit associative, non-associative and imprinted memory in the context of chemical stimuli is well established. Here we demonstrate that C. elegans nematodes are capable of spatial learning in a structured environment (maze). We use 3D-printing technology to build the custom-made Worm-Maze platform, a novel and versatile behavioral arena. We show that C. elegans young adults can locate food in T-shaped mazes and, based on this experience, they can learn which maze arm to reach, after a single training session. Results indicate that learning is sufficient to introduce bias in the decision-making process, even when in contradiction with inherent preferences. We provide evidence that C. elegans food location ability in the maze requires tactile input and functional proprioception, and that learning depends on chemosensation and mechanosensation. We also show that CREB-like transcription factor and dopamine signaling pathway are involved. C. elegans learning in the maze environment shares certain properties with the working memory mechanism, especially regarding timeframe of retention and sensitivity to environmental change. Moreover, it deteriorates with age earlier than food location ability decline. This is the first time that spatial learning is established and extensively characterized in C. elegans, and the underlying mechanism is explored.

Blau, Axel et al. (2015) International Worm Meeting "Si elegans - A neuromimetic emulation platform for exploring C. elegans' neurobiology and behavior."

Ferrara, Lorenzo, Callaly, Frank, Morgan, Fearghal, Mc Ginley, Brian, Leskovsky, Peter, Blau, Axel, Machado, Pedro, Krewer, Finn, McGinnity, Martin, Epelde, Gorka, Petrushin, Alexey, Mujika, Andoni

[International Worm Meeting, 2015]

Despite being one of the five best-characterized model organisms, there is still only sparse knowledge on how C. elegans' nervous system codes for its rich behavioral repertoire. The European Si elegans project aims at unravelling C. elegans' nervous system function (hermaphrodite) by its emulation with 302 parallelly interconnected field-programmable gate array (FPGA) neurons and by embodying this hardware nervous system with a biophysically accurate soft-body representation in a virtual behavioral arena. We critically discuss past and present neurocomputational approaches and pitfalls of simulating nervous system function. We then present the first Si elegans implementation and system integration steps with focus on its key components and challenges. The biophysics-based simulation platform shall allow scientists to test neural processing hypotheses and (un)published behavioral paradigms. Users will have access to all currently known and biologically relevant variables for the reverse-engineering of nervous system function to confirm or even anticipate some of the underlying principles. This contribution aims at opening a scientific discourse on the requirements, possibilities and limits of the faithful biomimetic emulation of an organism from both the biological and engineering perspectives.Acknowledgements: This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement ndeg 601215, FET Proactive, call ICT-2011.9.11: Neuro-Bio-Inspired Systems (NBIS). www.si-elegans.eu.

Yan, Wenwei Richard et al. (2021) International Worm Meeting "Real-time volumetric whole-animal imaging at cellular resolution with SCAPE microscopy in NeuroPAL worms"

Yemini, Eviatar, Yan, Wenwei Richard, Hillman, Elizabeth M. C., Li, Wenzi, Hobert, Oliver

[International Worm Meeting, 2021]

Recording neural activity at single cell resolution during unrestrained behavior holds tremendous potential for investigating the C. elegans neural code on a global scale. As fluorescent calcium indicators and 3D microscopy speeds have improved, recording from 100's of cells in moving worms has become feasible. However, 2 problems remain 1) being able to extract robust information from individual cells in a moving worm, and 2) knowing the defined identity of each individual tracked cell. Recently, a novel C. elegans strain termed NeuroPAL was developed that labels individual neuronal identities via a stereotypical multi-color fluorescence map. To harness the power of this worm we developed a high-speed multispectral volumetric microscopy platform with sub-cellular resolution, optimized for the NeuroPAL worms. Our SCAPE microscopy-based approach uses a scanning oblique light sheet which provides low phototoxicity and optical sectioning capabilities in a convenient single-objective geometry compatible with common C. elegans sample mounting procedures. The system's multi-laser launch, spectral image splitter and high-speed intensified camera make it possible to rapidly acquire a fully 3D NeuroPAL image in under 0.3 s. These scans can be interspersed with dual channel imaging of GCaMP and RFP with 0.33 x 0.67 x 0.25 microm sampling density over a 310 x 210 microm FEP-covered agarose arena at 13 volumes per second. The resulting data suggests much simpler tracking of uniquely identifiable cells throughout the worm, and analysis of the cellular calcium dynamics during free behavior.

Sanders, Tom et al. (2015) International Worm Meeting "Nonlinear sensory integration in C. elegans: a computational model."

Cohen, Netta, Ghosh, D.D., Sanders, Tom, Nitabach, M.N.

[International Worm Meeting, 2015]

Animal survival depends on a combination of often conflicting demands such as foraging and evading of dangers. To navigate effectively in such unknown and changing conditions, animals must continuously integrate over a variety of sensory cues, and adapt their decision making strategy in a context dependent manner. Here, we examine the neural control of a sensory integration task in the nematode C. elegans. The task involves an ASH-triggered aversive response to high osmolarity fructose and an AWA-triggered attractive response to diacetyl [1]. In the assay, worms are placed in the center of a ring of fructose; two drops of diacetyl are located outside the ring. We present a computational model, consisting of point worms, situated in a virtual arena that closely mimics this experimental assay, and endowed with a sensory motor pathway of two sensory neurons, a neural integration pathway and two motor programs (pirouettes and steering). A monoamine (PDF-2 and tyramine) modulation circuit involving RIM and ASH is overlaid on the synaptic circuit, in line with molecular data [1]. Model parameters were constrained by behavioral data for wild type and mutant animals for a range of stimulus concentrations. Based on our simulation results, we reject a null hypothesis of a linear sensory integration mechanism in RIM and present results that are consistent with the data for a sensory "coincidence detector" like process in RIM.[1] Ghosh, D.D., Sanders, T., Hong, S., Chase, D.L., Cohen, N., Koelle, M.R., and Nitabach, M.N. "Neuroendocrine reinforcement of a dynamic multisensory decision." International C. elegans meeting.

Albrecht, Dirk R et al. (2009) International Worm Meeting "C. elegans behavior in dynamic microfluidic environments."

Bargmann, Cori, Albrecht, Dirk R

[International Worm Meeting, 2009]

Neuronal circuits that govern goal-directed behaviors such as chemotaxis are highly interconnected, suggesting that their emergent functions may not be evident from the properties of individual neurons or connections. To study the underlying neural computation and dynamics, an engineering approach would systematically quantify output responses to many precise inputs under many circuit perturbations. While C. elegans locomotory behaviors are easily measured, and genetic tools enable precise circuit modification, the presentation of input stimuli in typical agar-plate assays is often poorly controlled. To address this limitation, we developed microfluidic liquid-filled arenas that enable the study of freely-moving animals in highly precise and dynamic microenvironments. We first optimized arena geometry to mimic C. elegans crawling motion, speed, and behavioral responses on agar surfaces. Microfluidic features create controlled liquid gradients that span several cm for population behavior or change sharply across the animal (<50 micron), and remain stable for hours or change rapidly within seconds. The transparent arenas are compatible with light-based neural control (via genetically-encoded rhodopsins) and fluorescent readouts of neural activity. We are characterizing wildtype C. elegans responses to complex spatial and temporal odorant patterns (steps and ramps) to understand how modulation of specific behaviors (e.g., speed, types of turns) influences chemotaxis strategy. Similar studies of genetic mutants with disrupted neurons or neuronal connections are revealing the role of perturbed information flow in directing these behaviors. For example, we found new behaviors (gradient-directed turning), new circuit pathways (glutamate-independent speed regulation), and strong phenotypes in subtle neuromodulatory mutants. Overall, the vast improvement in stimulus control in these microfluidic arenas enables new studies to understand the flow of information in neural circuits governing behavior.

Sato, Hirofumi et al. (2015) International Worm Meeting "A gustatory neural circuit for experience-dependent salt chemotaxis in C. elegans."

Hashimoto, Koichi, Iino, Yuichi, Fei, Xianfeng, Kunitomo, Hirofumi, Sato, Hirofumi

[International Worm Meeting, 2015]

Caenorhabditis elegans shows experience-dependent behaviors to many environmental cues. For sodium chloride, worms are known to memorize a particular salt concentration and approach the memorized concentration. In this study, we therefore searched for the neural circuit required for the memory of salt concentration. First, we conditioned worms in different salt concentrations, and monitored the activity of the salt-sensing chemosensory neuron ASER and three downstream interneurons; AIA, AIB, and AIY. We found that ASER, AIB, and AIY changed the responses depending on the previously exposed salt concentrations. We investigated the response of ASER in more detail, and found that the basal calcium level of ASER might change depending on cultivation concentration, and the plasticity of ASER response seemed to be independent of inputs from other neurons. Next, to assess the contribution of the three interneurons to the behavior, we ablated them individually, and compared behavioral responses of those worms with wild type. As a result, the reversal frequency of cell-ablated worms was different from that of the wild type. However, cell-ablated worms showed normal salt chemotaxis under the tested conditions, indicating that there are redundancies in the neural circuit that processes the salt perception signal. Furthermore, we investigated the relationship between the neural response and locomotion of worms. We used a tracking-imaging system with microfluidic arena that allowed worms to crawl in a controlled liquid environment (Albrecht et al., 2011), and recorded locomotion of worms and neural responses simultaneously. The result showed that the speed of worms decreased only when salt concentration was decreased below cultivation concentration. However, ASER always showed an off-response to salt, indicating that there is an experience-dependent plasticity in the process that links the ASER response to moving velocity.