7 Papers found (0.009 seconds)

Maier, Wolfgang et al. (2013) International Worm Meeting "Characterization of a gene whose expression correlates with the food type-dependent effects on lifespan."

Chandra, Rashmi, Maier, Wolfgang, Alcedo, Joy

[

International Worm Meeting,

2013]

The lifespan of wild-type C. elegans is affected by different types of bacterial food sources through a mechanism that is distinct from food level restriction [1]. Because the mechanism that underlies the food type-dependent effects on lifespan remains unknown, we used microarray analyses to identify genes that are involved in this process. Through this approach, we have identified a set of 26 genes whose expression changes are correlated with longevity on different E. coli strains [1]. Strikingly, this set is enriched for "pathogen-response" genes. However, unlike their expression on different E. coli strains, these genes do not exhibit a similar effect in response to pathogenic bacteria [2]. Indeed, in some cases, the same gene could be up-regulated on one pathogen, but strongly down-regulated on another pathogen. Hence, the regulation of these genes does not necessarily reflect food toxicity, but a more complex modulation of gene expression in response to different food types. To gain a better understanding of how these genes might affect lifespan in a food type-dependent manner, we are characterizing one of these genes, the acyl coA dehydrogenase acdh-1, which has also been recently identified as a dietary sensor [3]. Thus, we are determining the acdh-1 mutant phenotypes in correlation with the gene's spatial and temporal expression patterns on different food sources. Since we have also found that sensory neurons and neuropeptide signaling are involved in the food-type effects on lifespan [1], we are assessing whether sensory inputs and neuropeptides affect acdh-1 function on different food types. Together, these studies could yield insight into the mechanisms underlying the food-type effects on lifespan and physiology. Refs: [1] Maier et al., 2010. Plos Biol 8, e1000376; [2] Shapira et al., 2006. PNAS 103, 14086-14091; [3] MacNeil et al., 2013. Cell 153, 240-252.

Miller, Julia et al. (2021) International Worm Meeting "Whole Brain Calcium Dynamics During Aversive Memory Recall"

Miller, Julia, Saifuddin, Fatema, Dunn, Raymond, L'Etoile, Noelle, Chandra, Rashmi

[

International Worm Meeting,

2021]

Memory provides an important survival benefit across many species, as failure to recognize signals associated with harmful agents can be deadly. For example, the pathogenic bacteria Serratia marcescens emits butanone and acetone which attract the nematode C. elegans, but if ingested it kills the animal within days. However, worms that survive learn to avoid the bacteria to refrain from further ingestion. We use a spaced cycle odor-training paradigm to induce learning in C. elegans by pairing butanone with starvation, and this olfactory memory can last over 16 hours. However, the changes in neural dynamics that allow an animal to make the choice to avoid an odor are still unknown. We want to understand the full complement of neurons, their activity, and the interplay between neuron ensembles that coordinate movement to and away from the odor as a function of memory. As a first step, we will train worms in either butanone or buffer (as a control) in three 80' odor exposures interrupted by 30' feedings in the absence of the odor. We will then image restrained worms that express GCaMP6f in the nuclei of all neurons and present butanone to their nose to ask if butanone exposure elicits calcium changes reflective of the worm's behavior in a chemotaxis assay. Animals trained in buffer chemotax towards butanone, and thus we expect they will show reduced turns and backing during butanone exposure. We predict these behaviors will correlate with lower activity in the neurons AIB and AVA. By contrast, if the animals have learned to avoid butanone, those animals will increase turns and backing, and AIB and AVA will show higher activity under the same odor presentation paradigm. These experiments will also provide us an unbiased approach to identify other neurons important to a learned response. We might predict that the baseline neural dynamics will be the same in buffer and butanone trained animals, in which we may be able to identify the sequence of neurons whose activation elicits butanone attraction in buffer trained animals or repulsion in butanone trained animals. Examining the patterns of activity within the butanone-sensing circuit as well as the interactions with other neuronal ensembles will provide us with important insight into the decision-making process and how it changes after learning.

Chen, Alec J et al. (2022) MicroPubl Biol

Zuazo, Carlos, Mellman, Katie, Chen, Alec J, L'Etoile, Noelle, Chandra, Rashmi

[

MicroPubl Biol,

2022]

C. elegans' experiences and microbiome have been shown to shape its responses to certain stimuli; a recent study found that C. elegans grown on Providencia alcalifaciens JUb39 exhibited increased attraction to that same growth bacteria while also lowered replusion to the odor 1-octanol (O'Donnell et al. 2020). This prompted us to ask whether other strains of bacteria could likewise alter C. elegans' responses to bacterial food and volatile chemicals. So, to expand upon current knowledge, we cultured wild-type C. elegans (N2) on an unidentified Escherichia coli ( E. coli sp?), Pseudomonas mendocina (MSPm1), Pseudomonas lurida (MYb11), Stenotrophomonas maltophilia (JUb19), or Proteus mirabilis strain ( P. mirabilis sp?). After several generations, we examined how their choice of bacterial food was affected. In addition, we looked at their response to the olfactory stimuli 2-butanone; 2,3-butanedione; 2,3-pentanedione; and 2-nonanone, as well as their response to the gustatory stimulus sodium chloride. Interestingly, we found that growth on any of these bacterial strains led to their bacterial preferences and behavioral responses to 2-butanone; 2,3-pentanedione; diacetyl; and sodium chloride remaining unchanged. However, we also saw that C. elegans showed a preference for MSPm1 and P. mirabilis sp? to HB101, and HB101 to MYb11. Furthermore, worms that are grown on MSPm1 showed stronger attraction to a 1:10 dilution of 2-nonanone (AWB-sensed odorant) as compared to worms grown on the other bacterial strains.

Saifuddin, Mashel Fatema et al. (2021) International Worm Meeting "Olfactory memory consolidation requires the TRPV channel OSM-9 in sensory neurons of the circuit."

Miller, Julia, L'Etoile, Noelle, Chandra, Rashmi, Chen, Alec, Benedetti, Kelli, Gallegos, Maria, Dunn, Raymond, Zhang, Bo, Kaye, Julia, Saifuddin, Mashel Fatema, Kato, Saul

[

International Worm Meeting,

2021]

Memory is one of the most important abilities of the brain. It is defined as an alteration in behavior as a consequence of an experience. For example, the C. elegans nematode will downregulate its chemotactic response to the innately attractive odor, butanone, if the odor is not paired with food. Through repeated, spaced training with this odor in the absence of food, C. elegans will maintain this memory for a prolonged period of time. Although transient receptor potential (TRP) channels are classically thought of as primary sensory receptors, it was reported that the OSM-9/TRPV5/TRPV6 (TRP vanilloid 5/6) channel is required for single exposure learning. Here we describe a new role for osm-9 in consolidation of memory that is induced by repeated, spaced training. In this paradigm, osm-9 mutant animals learn as well as wild-types, but are unable to consolidate the memory. Though sleep is required for memory consolidation, loss of the TRPV channel OSM-9 does not affect sleep. This indicates that the TRP channel promotes memory in a process that acts outside the sleep pathway. We investigate the endogenous expression pattern of OSM-9 and show that it is not expressed in the butanone-responsive AWC olfactory sensory neuron. Instead, it is expressed in the paired AWA olfactory neuron, the ASH nociceptive neurons, the OLQ and two other unidentified sensory neurons which are most likely ADF and ADL as they express osm-9 mRNA. Because OSM-9 acts in sensory neurons that do not participate in butanone sensation, this indicates that the circuit participates in olfactory memory consolidation.

Sheffy Levin, S. et al. (2011) International Worm Meeting "Regulation of Autophagy by RNF-5, an E3 Ubiquitin Ligase."

Sheffy Levin, S., Broday, L.

[

International Worm Meeting,

2011]

The three main protein degradation pathways in the cell are the proteasome, the lysosome and autophagy. Autophagy is a general term for processes by which cytoplasmic materials including organelles reach lysosomes for degradation. Ubiquitin-E3 ligases are the components of the ubiquitin machinery that confer specificity to the ubiquitination process by recognizing target substrates and mediating transfer of ubiquitin from an E2 ubiquitin-conjugating enzyme to the substrate. The RING finger E3 ligase RNF-5 is an ER-bound protein implicated in ER-associated degradation (ERAD). Using the LGG-1/LC3::GFP reporter [1] we revealed that RNF-5 inhibition caused an increase in autophagy . Our purpose is to understand the mechanism by which RNF-5 regulates autophagy. rnf-5(tm794) mutant worms are more resistant to ER stress than wild-type animals, as assessed by exposing them to tunicamycin, an inhibitor of N-glycosylation. This resistance was reduced when different components of the autophagy core machinery were knocked down, suggesting that the activity of RNF-5 in the regulation of ER homeostasis is mediated through autophagy. Life span analysis revealed that elevated levels of RNF-5 in eat-2(ad465) mutant worms, but not in wild-type worms, suppressed their longevity phenotype. Since autophagy is required for the longevity of eat-2 worms [2, 3], we conclude that elevated expression of RNF-5 reduced autophagy in these animals and diminished their longevity. Together these data suggest that RNF-5 is a negative regulator of autophagy. 1. Melendez, A., Talloczy, Z., Seaman, M., Eskelinen, E.L., Hall, D.H., and Levine, B. Autophagy genes are essential for dauer development and life-span extension in C. elegans. Science, 2003. 301(5638): p. 1387-91. 2. Hansen, M., Chandra, A., Mitic, L.L., Onken, B., Driscoll, M., and Kenyon, C. A role for autophagy in the extension of lifespan by dietary restriction in C. elegans. PLoS Genet, 2008. 4(2): p. e24. 3. Jia, K. and Levine, B. Autophagy is required for dietary restriction-mediated life span extension in C. elegans. Autophagy, 2007. 3(6): p. 597-9.

Munoz-Lobato, Fernando et al. (2021) International Worm Meeting "Sleep is required for odor exposure to consolidate memory and remodel olfactory synapses."

[

International Worm Meeting,

2021]

Sleep is not only an essential function of humans but remains conserved across metazoans. Here we demonstrate that wild-type C. elegans sleep after repeated odor trainings This provides us with a platform to dissect how sleep affects memory at a synaptic resolution. We identified that sleep immediately after training is required for the animal to retain a long-term memory of the odor. We found that if animals do not sleep in the first two hours after training, memory is not consolidated. After identifying the neurons that are required for the memory, we show that the sensory-interneuron connections within the circuit are downscaled after sleep. Therefore, we found a time-specific requirement of sleep that modulates synaptic downscaling to preserve memory. Conversely, lack of sleep post-training erases the long-term memory and destabilizes the synaptic downscaling, indicating that modulating the amount of sleep is sufficient to modulate memory. These results make C. elegans an excellent tool to ask what molecular mechanisms, cell biological processes and circuit level reorganizations are engaged during sleep to promote memory. This understanding will provide insights into the functions of sleep that contributes to our health and well-being.

Wei B et al. (2018) MicroPubl Biol "oxi-1 and fshr-1 are required for neuromuscular signaling under normal and oxidative stress conditions in C. elegans"

Kowalski JR, Wei B

[

MicroPubl Biol,

2018]

Reactive oxygen species (ROS) contribute to neuronal degeneration by readily reacting with cellular components, consequently breaking down cellular integrity. Excess ROS often leads to oxidative stress, which results from destabilization of the organisms ability to control the balance between antioxidants and free radicals (Chandra et al. 2015). The ubiquitin-proteasome system helps to regulate oxidative stress and overall damage to cellular components by forming chains of ubiquitin polypeptides on cellular proteins; these chains then serve as a signal to break down the attached protein (Hershko et al. 1983). Mutation of UBE3B, an E3 ubiquitin ligase, has been found to lead to Blepharophimosis-Ptosis-Intellectual-Disability Syndrome (BPID) in human infants, indicating potential involvement of UBE3B in the regulation of neuronal signaling in the brain (Basel-Vanagaite et al. 2012). The UBE3B protein was also shown to be involved in mitochondrial function and oxidative stress responses in mammalian cells (Braganza et al. 2017). In C. elegans, the oxi-1 gene encodes an ubiquitin ligase homologous to UBE3B (58% amino acid similarity); expression of C. elegans oxi-1 is induced by oxidative stress and is required for proteasomal responses to this stress (Basel-Vanagaite et al. 2012). However, despite the link to neurodevelopmental disorders including BPID, specific roles for UBE3B or oxi-1 in neuronal biology and synaptic function, with or without oxidative stress, have not been explored (Basel-Vanagaite et al. 2012). A second C. elegans gene fshr-1, which encodes a G protein-coupled receptor homologous to a family of mammalian glycopeptide hormone receptors (Cho et al, 2007), is also involved in both oxidative stress responses and neuronal signaling. Specifically, fshr-1 regulates expression of gcs-1, an oxidative-stress response gene (Miller et al. 2015) and was identified in an RNAi interference screen as a gene required for proper structure and function of neuromuscular synapses (Sieburth et al. 2005). Despite data suggesting roles for oxi-1 UBE3B, and fshr-1 in neuronal signaling, which is susceptible to oxidative damage, neither gene has been investigated with regards to neuronal signaling in the presence of oxidative stress. Here, we tested the requirements of both oxi-1 and fshr-1 for their effects on neuromuscular signaling under both normal and oxidative stress conditions in C. elegans. Neuronal signaling activity can be measured at the neuromuscular junction in C. elegans, a model synapse, by observing the motility of individual worms in liquid medium in a body bending assay (Nawa and Matsuoka 2012). Under normal conditions, C. elegans mutants lacking expression of either oxi-1 or fshr-1 had reduced motility compared to wild type animals by 11.0% (p < 0.0001= 2.1167E-05) and 11.2% (p < 0.00001= 3.8259E-06), respectively (Figure 1A). Following exposure to oxidative stress conditions (5 mM paraquat) for 48 hours, the mean number of body bends for wild type animals remained constant (normal: 194 body bends/minute, oxidative stress: 199 body bends/minute). However, the motility of oxi-1 mutants compared to wild type N2 worms under oxidative stress conditions in the body bending assay decreased from 173 to 160.5 body bends/minute, a 19.2% reduction compared to the wild type strain (p < 0.001= 1.77E-04) (Figure 1B). An even larger decrease in body bends, from 172.5 to 140.8 body bends/minute, a decrease of 29.2% (p = < 0.00000012.1771E-08) was observed for fshr-1 mutants compared to wild type animals under oxidative stress conditions (Figure 1B). Successful induction of oxidative stress was determined for each body bending assay by assessing whether a separate strain of worms (IdIs3) carrying the oxidative stress responsive reporter gcs-1p::GFP exposed to paraquat alongside oxi-1, N2, and fshr-1 expressed green fluorescence when observed under a fluorescence stereomicroscope.