Wang, W. et al. (2019) International Worm Meeting "Ursolic Acid promotes neurite outgrowth and protects against axon degeneration in Caenorhabditis elegans."

Pocock, R., Wang, W., Xiao, Z.

[International Worm Meeting, 2019]

Correct development and maintenance of neuronal architecture is required for proper brain function. Nascent neurons connect with each other through axons and dendrites that derive from neurites. Therefore, outgrowth and structural maintenance of neurites is crucial for a well-organized neuron network. After neural injury or in neurodegenerative disease, axons distal to the injury site exhibit cytoskeletal disassembly and degeneration, known as axonal degeneration. Ursolic acid (UA), a naturally occurring pentacyclic triterpenoid, was first identified in the epicuticular waxes of apples and exists in many fruits and herbs, such as cranberry and rosemary. Various reports have suggested the potential therapeutic application of UA in neural injuries, inflammation, cancer, and diabetes. In this study, we examined neuroprotective activity of UA in Caenorhabditis elegans. We found that UA reduces axon outgrowth defects of the PVQ interneurons in animals defective for the CED-10/Rac1 protein. UA also promoted axon outgrowth in other mutants that affect the Rac1 pathway in C. elegans. Further, we found that the axon outgrowth-promoting effect of UA occurred during embryogenesis. In addition, we found that UA reduces axon degeneration in mutants lacking the MEC-17/?-tubulin acetyltransferase 1, which causes spontaneous, adult-onset axonal degeneration of the PLM mechanosensory neurons. Interestingly, UA treatment in the parental generation suppressed the axon degeneration defects of descendants for several generations. Together, our findings show that UA can promote axon outgrowth and prevent axon degeneration. Therefore, UA has potential therapeutical applications in neurodegenerative disease. Further work will identify the molecular mechanism through which UA protects the nervous system.

Negi, H. et al. (2017) International Worm Meeting "3beta-Hydroxy-urs-12-en-28-oic acid prolongs lifespan in C. elegans by modulating JNK-1."

Shukla, A., Khan, F., Negi, H., Pandey, R.

[International Worm Meeting, 2017]

Remarkably the c-Jun-NH2-terminal kinase (JNK) pathway is all evolutionarily conserved across species. In view of the hypothesis that increased stress resistance subdue aging, we investigated the role of ursolic acid (3 beta -Hydroxy-urs-12-en-28-oic acid; UA) in the pioneering aging model Caenorhabditis elegans with an increase in mean and maximum lifespan by up to 30%. Our genetic study unravelled the underlying pathway where JNK-1 is acting independently of insulin-IGF-1 signalling (IIS) pathway to modulate longevity. In support of in vivo results in silico docking study of UA with C. elegans JNK-1 ATP-binding site suggested promising binding affinity exhibiting binding energy of -8.11 kcalmol-1. UA induced JNK-1 activation in wild-type animals underlie the importance of pharmacological interventions in the delineation of molecular targets for aging and associated pathologies.

Grinan Ferre, Christian et al. (2021) International Worm Meeting "Synergistic Neuroprotective Effects of Mix Extract from Biosearch Life Product Against AD-hallmarks and Cognitive Decline in Caenorhabditis elegans and SAMP8 Mice Model"

Banuelos-Hortiguela, Oscar, Grinan Ferre, Christian, Bellver-Sanchis, Aina, Olivares-Martin, Monica, Pallas, Merce

[International Worm Meeting, 2021]

Neurodegenerative diseases such as Alzheimer's disease (AD) are well recognized as major public health problems in the aged population. Recognized events in AD include cognitive impairment, oxidative stress (OS), AB plaques accumulation in brain tissue. The current drugs to treat AD no cure or reduce the progression of the disease. Thus, the study of different extracts can provide a wealth of bioactive compounds and their combination, which can exert a new strategy for several neurodegenerative diseases, including AD. Among the natural extracts, Ginkgo biloba is one of the most investigated herbal remedies for cognitive disorders and AD. Moreover, docosahexaenoic acid (DHA), and Pinitol and Ursolic acid (UA) are associated to a prophylactic role in certain age-related diseases with particular emphasis on some of the effects of certain degenerative diseases. This study aimed to investigate the synergistic neuroprotective effects of mixed extract composed by different concentrations of DHA (150 microM), Ginkgo (120 microM) Pinitol (105 microM), and UA (35 microM) from Biosearch Life product, including OS tolerance, Thioflavin-S staining AB plaques, and lifespan in several transgenic Caenorhabditis elegans (C. elegans) as well as cognitive performance in C. elegans and senescence-accelerated prone mice 8 (SAMP8) model. Firstly, we found a significantly higher survival percentage in C. elegans treated with Mix extract group in comparison with the single extract treated groups (DHA 150 microM group, Ginkgo 120 microM group, Pinitol 105 microM group, UA 35 microM group), reaching the Vitamin C group. Likewise, we found a significantly increased the lifespan in C. elegans Mix extract-treated group compared to the other groups, suggesting the synergistic effects. Remarkably, we determined a significant reduction in AB plaques accumulation in C. elegans strain CL2006 Mix extract group compared to other groups, including all treated groups, confirming the synergistic effect again. Finally, we demonstrated better cognitive performance in the Mix extract group in both AD models (neuronal AB C. elegans strain CL2355 and SAMP8 mice model), confirming the molecular result and demonstrating the synergist effects of this Mix extract. Taken together, our results demonstrated the potential therapeutic strategy for AD of this new Mix extract product from Biosearch Life.

Raj, Vishnu et al. (2017) International Worm Meeting "Degeneration of dopamine neurons affects memory formation in Caenorhabditis elegans."

Mangalath, Aswathy, Raj, Vishnu, Santhosh, Rasitha, Nair, Agrima, Thekkuveettil, Anoopkumar, Vijayan, Bejoy

[International Worm Meeting, 2017]

Degeneration of dopamine neurons often found to develop dementia as a comorbidity. It is not deciphered, however, the involvement of the dopamine connectome in memory formation as well as in dementia. Caenorhabditis elegans is an excellent model system to study the connectome variations because of its elementary and well-mapped nervous system. The four CEP neurons in the head region of the organism use dopamine as their neurotransmitter and play a critical role in the movement. To understand the role of dopamine circuit in learning, we used adaptive learning paradigm of Caenorhabditis elegans to olfactory cues. Significantly low associative learning towards butanone was observed in mutant DAT-1::ICE, which develops dopamine neuron degeneration in their late larval stages. These results were comparable to that of mutants of str-2, a G-protein coupled receptor in AWC neurons, having a significantly low associative learning. A similar pattern of learning defects were observed in UA-44 strain with age-associated dopamine neurodegeneration. However, Cat-2 and Tph-1 mutants, which are defective in dopamine and serotonin synthesis respectively, showed no significant changes in learning pattern. These findings suggest dopamine connectome have a critical role in memory formation.

Jami Milton Dantzker et al. (2002) West Coast Worm Meeting "Imaging neuronal activity in AWC chemosensory neurons"

Jami Milton Dantzker, Cori I Bargmann

[West Coast Worm Meeting, 2002]

Particular odorants reliably elicit chemotactic behaviors from C. elegans, but the response can depend on odorant concentration, odorant type and the initial state of the animal. The detection of several volatile attractive odorants is mediated by the AWC chemosensory neuron pair; analyses of animals mutant in their ability to recognize these odorants have revealed many gene products involved in AWC olfactory signaling. However, it has been difficult to study the effect of olfactory stimulation on the activity of chemosensory neurons themselves. Recently, the Schafer lab has successfully measured neuronal activity by using the genetically encodable calcium indicator cameleon. Our goal is to optimize calcium imaging of AWC chemosensory neurons in live animals presented with attractive volatile odorants, including benzaldehyde, butanone and isoamyl alcohol. We will probe the variation of calcium transients that can be elicited by odorant type, concentration, and stimulations at different durations and time intervals. We will evaluate how molecular components of olfactory transduction pathways influence calcium signaling and behavior by measuring calcium transients in chemotaxis mutants.

Lassegue, Circe et al. (2011) International Worm Meeting "Do ascarosides affect egg-laying behavior in Caenorhabditis elegans?"

Lassegue, Circe, Edison, Arthur, Nimalendran, Rathika, Ajredini, Ramadan

[International Worm Meeting, 2011]

Caenorhabditis elegans, a small transparent nematode that lives in temperate soil environments, is one of the simplest eukaryotic organisms with a nervous system to be studied in great detail. Over recent years, a large number of ascarosides have been identified as signaling molecules in C. elegans (Edison, 2009). Ascaroside levels are affected by worm concentration and available food when developed in "worm water". Ascarosides have been shown to regulate a large number of behaviors in C. elegans including dauer formation (Butcher, et al., 2007), mating behavior ((Srinivasan, et al., 2008), aggregation (Macosko, et al., 2009), and olfaction (Yamada, et al., 2010). Additionally, environmental and homeostatic cues are now being explored to see how these affect nematode egg-laying habits (Schafer et al., 2001). We studied the modulatory effect of several ascarosides on egg-laying behavior and brood size in adult female C. elegans. This study aims to determine the effect of ascarosides on egg-laying behavior in adult C. elegans. A range of concentrations of several synthetic ascarosides as well as natural worm water produced by C. elegans were studied. Standard egg-laying assays and known positive and negative controls were utilized (Koelle, 2004).

Zhaoyang Feng et al. (2003) International Worm Meeting "C. elegans, a genetically tractable model for the study of nicotinic signaling"

Anthony Kempf, William Schafer, Zhaoyang Feng, Marika Orlov

[International Worm Meeting, 2003]

Nicotine abuse is the most critical but preventable public health problem. Although nicotinic acetylcholine receptor (nAChR) is identified as the main target of nicotinic signaling, the molecular and neuronal circuits of nicotinic signaling remain unknown. Using invertebrate models such as c. elegans or Drosophila metanogaster as animal models to study drug abuse has recently attracted the attention of researchers because of their simple nervous system, and the available powerful genetic tools in these models [Schafer WR, J. Neurosciences, 2002, Wolf FW and Heberlein U, Cur. Opp. in Neuroscience, 2003]. Utilizing a quantitative c. elegans behavior analysis system (Feng Z. et al, abstract in this meeting), a c. elegans locomotory acclimation behavior is identified and defined. Using this locomotory acclimation behavior as a behavioral assay, the c. elegans animals were found to response acutely to nicotine at a wild concentration range including concentrations close to physiological concentration in human blood after a cigarette consummation. This locomotory acclimation behavior is also found can be used in the study of nicotine adaptation, withdrawal, and possibly sensitization. The distinct roles of several nicotinic receptor subunits (unc-29, unc-38, and unc-63), Go and Gq signaling circuits, and several neuronal transmitters (dopamine, serotonin, glutamate) in the locomotory acclimation behavior, and their functions in nicotinic signaling are discussed.

M Dekkers et al. (2004) European Worm Meeting "IN VIVO IMAGING OF GUSTATORY SIGNALLING IN C. ELEGANS"

M Dekkers, G Jansen

[European Worm Meeting, 2004]

We are interested in the molecular and cellular mechanisms that govern gustatory plasticity. Using behavioural assays, we have identified many signalling molecules that are involved in this behaviour. In addition, we have identified several pairs of sensory neurons that mediate gustatory plasticity: the ASE neurons provide an attractive signal in response to NaCl, which is balanced by inhibitory inputs from the ASI neurons and the nociceptive neurons ASH and ADL. In a parallel approach we use genetically encoded probes to image the responses of single cells upon stimulation. We drive expression of these imaging constructs in the cells mentioned above using cell-specific promoters. The primary reporter construct we use is the Cameleon construct (Miyawaki et al 1999), which uses Fluorescence Resonance Energy Transfer (FRET) to visualise changes in the calcium levels in the cytosol. We have optimised imaging using an sra-6-prom::Cameleon line (kindly provided by the Schafer lab, with feedback), which is expressed in ASH. Besides the Cameleon construct we are also testing a construct that is a measure for PIP2 hydrolysis in the membrane (van der Wal et al 2001) and a pH sensitive derivate of GFP, pHluorin (Miesenbck et al.1998), as a reporter for vesicle release in the synaptic cleft. Together with the data from the behavioural assays, this will allow us to further dissect the intercellular and intracellular signalling routes leading to gustatory behaviour.

Daniel L Chase et al. (2003) International Worm Meeting "Dopamine-resistant mutants of C. elegans identify components of Go and Gq signaling pathways"

Daniel L Chase, Judy S Pepper, Michael R Koelle

[International Worm Meeting, 2003]

Dopamine, a major neurotransmitter in the mammalian central nervous system, acts through two classes of G protein-coupled receptors known as D1-like and D2-like receptors. These two classes of receptor signal to antagonistically regulate neural activity. Despite intensive research, the signaling mechanisms responsible for the antagonistic effects of dopamine in the brain remain debated. We describe the first genetic screen designed to identify proteins required for dopamine signaling. C. elegans uses endogenous dopamine to inhibit locomotion behavior1, and treatment with excess exogenous dopamine paralyzes worms2. We isolated mutants unresponsive to exogenous dopamine and found that they are also defective for endogenous dopamine signaling. Eleven mutations identified five different genes. Four of these genes encode components of the Go and Gq signaling pathways, including the G protein Go itself and subunits of the RGS complex that inhibits Gq signaling. The Go and Gq signaling pathways act antagonistically in C. elegans to control behavior and their components are conserved in humans. Mutations in these signaling components that decrease Go signaling or increase Gq signaling cause dopamine resistance, while mutations that have opposite effects on these two signaling pathways cause dopamine hypersensitivity. Thus the physiological effects of dopamine are mediated by Go in C. elegans and are antagonized by Gq signaling. Such a dopamine signaling mechanism in mammals could explain many of the opposing effects of D1-like and D2-like receptor activation. Our screen also identified one gene that appears to encode a new Go/Gq signaling component. 1. Sawin, E.R., Ranganathan, R., and Horvitz, H.R. (2000). Neuron 26, 619-631; 2. Schafer, W.R., and Kenyon, C.J. (1995). Nature 375, 73-78.

Tod R Thiele et al. (2005) International Worm Meeting "The role of identified neurons in the sensorimotor transformation underlying C. elegans chemotaxis."

Tod R Thiele, Shawn R Lockery

[International Worm Meeting, 2005]

C. elegans climbs a gradient of chemical attractant by modulating its turning frequency in response to changes in chemical concentration. The sensorimotor transformation underlying chemotaxis has been defined by recording the behavior of unrestrained worms in a NaCl step-response assay. An increase in salt concentration (an upstep) increases the probability of forward locomotion (run behavior), whereas a decrease in concentration (a downstep) increases the probability of reversals and omega bends (turn behavior). Toward characterizing the neural mechanisms of the chemotaxis sensorimotor transformation, we have been identifying essential neurons by laser ablation in combination with the step-response assay. Previously we have shown that the chemosensory neuron ASE is necessary for turn behavior but unnecessary for run behavior. Calcium imaging experiments (H. Suzuki & W. Schafer UCSD) have uncovered a functional asymmetry between ASER and ASEL. ASER responds to NaCl downsteps whereas ASEL responds to NaCl upsteps. Here we present the results of unilateral ASE ablations that further specify the functional roles of ASE neurons. In unilateral ASER ablations, we found that the amplitude of the downstep turn was strongly reduced, whereas the amplitude of the upstep run was normal. In unilateral ASEL ablations, we found that the amplitudes of the downstep turn and upstep run were normal. These results are consistent with a model in which ASER drives downstep turns whereas ASEL acts redundantly with other sensory neurons to drive upstep runs. We are currently in the process of identifying these other sensory neurons using laser ablation and calcium imaging. Our experiments are focusing on the neurons ADF, ASI and ASG which have been previously implicated in NaCl chemotaxis (Bargmann 1991).