Parmidge, Amelia et al. (2015) International Worm Meeting "Finding Neuro: Automating calcium image analysis."

L'Etoile, Noelle, Parmidge, Amelia, Young, Jared, Brueggemann, Chantal

[International Worm Meeting, 2015]

In recent years, fluorescent imaging has been used more and more to capture the state of biological systems at different moments in time. For many researchers, analysis of the fluorescent image data has become the limiting factor of this new technique. We have developed NEPIC, a semi-automated tool for finding and tracking the soma of a single neuron over an entire movie of grayscale calcium image data. When tested on calcium image movies of the AWC neuron in C. elegans under highly variant conditions, NEPIC correctly identified the neuronal soma in 95.48% of the movie frames, and successfully tracked this soma feature across 98.60% of the frame transitions. Although support for finding and tracking multiple fluorescing Regions of Interest (or fROIs) has yet to be implemented, NEPIC displays promise as a tool for assisting researchers in the bulk analysis of fluorescent imaging data.

Mitchell, Robin et al. (2021) International Worm Meeting "Reversal behavior upon encountering a cliff involves mechanosensation"

Mitchell, Robin, Young, Jared, Zhang, Shuyu, Pattillos, Diana

[International Worm Meeting, 2021]

The precipice response is a little-understood phenomenon in which C. elegans move rapidly away from edges or gaps in an agar plate. First described by Chalfie et al. (2014), this behavior has yet to be characterized by the research community, and up until now potential underlying mechanisms remained unexplored. We hypothesized that mechanosensation underlies the precipice response and that mutant worms with deficient mechanosensation would exhibit the precipice response less frequently than N2 wild-type worms. Our experiments sought to 1) characterize the precipice response and craft a sufficient biological definition, and 2) test our hypothesis about mechanosensation's role in the precipice response. N2 wild-type worms were used to define the precipice response. Using a wire or dog whisker pick, worms were transferred onto small chunks of agar with smooth, 90° edges. We observed that, indeed, worms had a strong tendency to quickly reverse when their head went over the edge of the agar. We defined the precipice response as a reversal initiated within two seconds of the head going over a 90° edge. This reversal must extend for a full sine wave within two seconds. In an initial dataset of 32 N2 worms, 26 of them (81%) exhibited the precipice response. To test whether mechanosensation plays an important role in the precipice response, we tested three strains of worms with varying degrees of mechanosensory deficiency: mec-3(e1338), mec-10(e1515), and trp-4(sy595). mec-3 mutants do not respond to light or harsh touch, while mec-10 and trp-4 mutants exhibit partial loss of response to mechanical stimuli. In blinded trials, we found that mec-3 mutants exhibited the precipice response less frequently than N2, mec-10, or trp-4 worms. Neither mec-10 nor trp-4 exhibited the precipice response at a frequency that was significantly different from the N2 strain. These results show that mechanosensation underlies the precipice response, and imply that near total loss of mechanosensation may be necessary to have a profound impact on the precipice response. This study is an illuminating first step in discerning the mechanisms of the precipice response in C. elegans, and may have broader implications in animal behavior.

Gutierrez, Paula M. et al. (2011) International Worm Meeting "Candidate mediators of the food block on olfactory adaptation."

L'Etoile, Noelle, Braslow, Joshua, Young, Jared, Gutierrez, Paula M.

[International Worm Meeting, 2011]

Animals sense a variety of environmental cues and can change their behavior as a consequence of the experience. For example, Caenorhabditis elegans is attracted to specific odors that are sensed by the paired AWC olfactory sensory neurons; however, the attraction decreases if exposure occurs in the absence of food, referred to as olfactory adaptation. We seek to further explore odor processing and its interaction with food sensory signals in the model organism C. elegans. Adaptation in C. elegans to particular odorants does not occur when exposure is accompanied by food. We are focusing on understanding the role of insulin signaling and oxygen sensing in the food block of adaptation by studying the behavior and neurobiology of mutant strains. Olfactory stimulation and the accompanying behavioral responses are important pathways for complex organisms and this fundamental project will contribute to its understanding.

Tee, Ling Fei et al. (2021) International Worm Meeting "Toward the understanding of molecular mechanism of electrical sensation and response"

Young, Jared, Kimura, Kotaro, Tee, Ling Fei, Suzuki, Ryoga, Maruyama, Keisuke

[International Worm Meeting, 2021]

Electricity is sensed by many animal species in addition to other stimuli, such as sound, light, and chemicals. Electricity is generally regarded to cause aversive responses, although it is also utilized and sensed for communication, navigation and/or prey detection not only by the well-known electric fishes but also by platypus, salamander and frog etc. The wide use of electricity as a type of environmental signal indicates the importance for animals to sense the world through electricity. However, compared to other environmental stimuli, the molecular mechanism(s) of sensing electricity is far less understood. The electrical sensor is known only in shark and skate, where the sensors are L-type voltage-gated calcium channels (VGCC) (Bellono et al. Nature 2017, 2018). By using a new behavioral paradigm, we are revealing the molecular mechanism of electricity sensation in worms. We first discovered that, when worms on food are stimulated by 32 V / 80 mA (4 Hz) AC, the worms' speed of migratory movement suddenly increases more than 2-fold, which persists for several minutes during electrical admission (ON response). Interestingly, a different response is observed when a stronger electric stimulus is applied: with 80 V / 200 mA (4 Hz), the speed does not increase on average during the stimulus but does increase immediately after the stimulus removal, which lasted for a few minutes (OFF response). This OFF response suggests that the speed increase is likely caused not by direct and/or non-specific motor activation but by activation of a sensory mechanism, probably something like an alert system. Genetic candidate analysis demonstrated that tax-2/4, osm-9;ocr-2, mec-4/10, cat-2, and tph-1 mutants showed wild type-like response, indicating that the conventional sensory mechanisms and the mechanisms for starvation-dependent speed increase are not required. Further, we found that, in addition to the above-mentioned L-type VGCC EGL-19, N-type VGCC UNC-2 is also involved, suggesting a new mechanism of electrical sensation. Currently, we are analyzing the neurons in which EGL-19 and/or UNC-2 function, the neurotransmitters required for the response, and the whole brain activities during the response (see abstracts by Wen). Combining findings from this series of experiments, we hope to elucidate the underlying molecular as well as neural mechanisms of electrical sensation and response which may be evolutionarily conserved across animal species.

Janzen, Laine et al. (2011) International Worm Meeting "Forward screen for mutants lacking a food block on olfactory adaptation."

L'Etoile, Noelle, Cha, Amanda, Ghafari, Ghazal, Llamas, Sara, Young, Jared, Janzen, Laine, Stinson, Pilar, Summers, Stephanie

[International Worm Meeting, 2011]

Context cues play a role in compulsive and addictive behaviors by endowing accompanying stimuli with increased salience. For example, olfactory cues such as food odors accompany the reinforcing stimulus of the food itself, and thus stimulate cravings for the reinforcing stimulus. We suggest important modulation of odor processing may occur in olfactory sensory neurons, and indeed recent studies have indicated that responses to odors may be modified early in the olfactory pathway (1,2). Olfactory adaptation is a basic form of learning that causes desensitization of an organism to an odorant after a prolonged period of exposure. Studies have shown that adaptation to an odorant can be repressed by the presence of food in the model organism C.elegans (3,4). This block of adaptation involves inhibition of changes in the primary sensory neuron which are associated with olfactory adaptation. As part of a larger project to study the molecular, cell biological, and circuit level mechanisms by which food-derived signals affect odor signaling and long-term plasticity in the model organism C.elegans, this project will attempt to identify new genes involved in the inhibition of long-term neuronal plasticity by food signaling in the sensory neuron (AWC). To identify new genes involved in the food block on adaptation, we are using an unbiased forward genetic screen to isolate mutants. This foundational project will contribute to a larger endeavor to reveal how rewarding stimuli alter signal processing within the primary sensory neuron and may inspire therapies for controlling debilitating compulsive behaviors, such as over eating or drug addiction. 1. Li W, Howard JD, Parrish TB, Gottfried JA. Aversive learning enhances perceptual and cortical discrimination of indiscriminable odor cues. Science. 2008 Mar 28;319(5871):1842-5. 2. Doucette W, Gire DH, Whitesell J, Carmean V, Lucero MT, Restrepo D. Associative Cortex Features in the First Olfactory Brain Relay Station, Neuron. 2011 Mar;69(6):1176-1187. 3. L'Etoile ND, Coburn CM, Eastham J, Kistler A, Gallegos G, Bargmann CI. The cyclic GMP-dependent protein kinase EGL-4 regulates olfactory adaptation in C. elegans. Neuron. 2002 Dec 19;36(6):1079-89. 4. Colbert HA, Bargmann CI. Environmental signals modulate olfactory acuity, discrimination, and memory in Caenorhabditis elegans. Learn Mem. 1997 Jul-Aug;4(2):179-91.

Cha, Amanda et al. (2013) International Worm Meeting "A forward screen to identify genes involved in the blockage of olfactory adaptation by food in C. elegans."

Knight, Jamie, Young, Jared, Engelhardt, Marie, Kettellapper, Kelsi, L'Etoile, Noelle, Summers, Stephanie, Cha, Amanda, Stinson, Pilar, Janzen, Laine, Ghafari, Ghazal

[International Worm Meeting, 2013]

C. elegans is attracted to specific odors sensed by the paired AWC olfactory sensory neurons; however, the attraction decreases if exposure occurs in the absence of food, referred to as olfactory adaptation. We seek to further explore odor processing and its interaction with food sensory signals in the model organism C. elegans. Adaptation in C. elegans to particular odorants does not occur when exposure is accompanied by Escherichia coli, a food source for the worm. Here we report results from a forward screen to identify genes involved in the block of olfactory adaptation by food. In the forward screen, F2 mutants were isolated based on their lack of attraction to an odor after the odor was presented along with food. The screen was carried out and 33 worms isolated as possibly interesting mutants. Further analysis, aimed at identifying lines with robust phenotypes, is focused on 7 of these lines.

Nathan, Sara et al. (2015) International Worm Meeting "Identifying and characterizing odor receptors in C. elegans."

Cox-Harris, Alesha, Brueggemann, Chantal, Mosqueda, Berenice, Young, Jared, Newman, Elizabeth, Nathan, Sara, Morton, Riva, Dalton, Cassidy, L'Etoile, Noelle, Apostol, Sherrlyne

[International Worm Meeting, 2015]

Although scientists have been studying olfaction in C. elegans for decades, olfactory receptor proteins remain largely uncharacterized. To address this knowledge gap, we are pursuing localization of candidate odor receptor proteins, and studying odor responses in genetically altered worms. We are producing lines with GFP-tagged putative odor receptors using constructs obtain from the Transgeneome project, and looking for proteins that localize to sensory cilia. We are testing chemotaxis to a variety of odors of worms in which expression of putative odor receptors have been reduced using RNA interference. We are also generating knockout worms for putative odor receptors using the CRISPR technique, to be tested in chemotaxis assays. .

Mori A et al. (2000) Japanese Worm Meeting "Studies on protein kinases involved in gametogenasis"

Higashitani A, Takahashi H, Takanami T, Mori A

[Japanese Worm Meeting, 2000]

Protein kinases are well known to play important roles, such as cell-cycle controls, apoptosis and stress responses. A lot of genes containing protein kinase domain are identified in the genome of C. elegans. However, the biological functions of their majority are still unknown. In order to isolate novel kinases involved in meiosis and gametogenasis, at first, we selected about 100 putative kinase genes in the genome. Their expression level were examined by RT-PCR reaction with total RNA from young adult and L2 larval hermaphrodite. After that, some genes whose expression levels obviously increased in young adults were investigated by the RNA interference method. As a result, we found that T08D2.7 is required for gametogenesis. In this presentation, we will discuss the results of functions of some protein kinases.

Xing, Xiaojuan (2010) C. elegans: Development and Gene Expression, EMBL, Heidelberg, Germany "Larvae nematode C.elegans evaluate neurobehavioral toxicity to metallic salts"

Xing, Xiaojuan

[C. elegans: Development and Gene Expression, EMBL, Heidelberg, Germany, 2010]

In this study, we investigated the locomotion behavior changes at different developmental stages in Caenorhabditis elegans exposed to metals for 4h. No obvious differences could be observed in young adults exposed to examined metals, and only exposure to 100 mM of examined metals could signi?cantly decrease the locomotion behaviors of L4 larvae. In contrast, exposure to 50 and 100 mM of examined metals induced noticeable repression of locomotion behaviors at L1L3 larval stages, and a signi?cant decrease of locomotion behaviors could be observed in L1 larvae exposed to Pb and Hg, and in L2 larvae exposed to Hg at the concentration of 2.5 mM. Moreover, the L1-, L2-, and L3- larvae exposed to metals for 4h exhibited similar neuro behavioral toxicity manner to L4- larvae exposed to metals for 24h. Therefore, younger larvae showed more severe de?cits in neuro behavioral phenotypes than L 4 larvae and young adults in metal-exposed nematodes.

Zimmerman, Stephanie et al. (2015) International Worm Meeting "Profiling the aging proteome in C. elegans reveals a new role for extracellular uterine proteins in aging."

Kim, Stuart, Zimmerman, Stephanie, Elias, Joshua, Hinkson, Izumi

[International Worm Meeting, 2015]

One way to understand aging is to use unbiased approaches to profile molecular changes that occur with age, and determine the cause and effect of these changes. In this study, we identify changes in the proteome during aging in C. elegans using mass spectrometry-based proteomics. We find that secreted proteins and proteins expressed specifically in adult animals tend to increase in abundance with age. A previously uncharacterized subset of these age-increased proteins are expressed solely in the extracellular space of the adult uterus. These uterine proteins dramatically accumulate with age, but this increase in abundance is blunted in animals with an extended reproductive period. This suggests that age-induced infertility, an early event in the aging process, is at least partially responsible for the accumulation of proteins in the uterus. Furthermore, we find that uterine proteins rapidly turn over in young adult animals, but are removed much more slowly in old worms. Uterine proteins are not removed in young vulvaless worms, which indicates that egg laying or another means of exit through the vulva is necessary for the rapid removal observed in wild-type young animals. Finally, we show that uterine protein accumulation is toxic for the animal, as knocking down multiple uterine proteins simultaneously can extend lifespan. These findings represent a novel link between reproductive and somatic aging, in which age-induced infertility contributes to changes in the soma that are detrimental for survival. .