Quamme, Elizabeth et al. (2021) International Worm Meeting "Exploring natural genetic variation influencing ethanol response behaviors."

Kammenga, Jan, Riksen, Joost, Quamme, Elizabeth, Mathies, Laura, Sterken, Mark, van Wijk, Marijke, Davies, Andrew, Bettinger, Jill

[International Worm Meeting, 2021]

The propensity to develop alcohol use disorder is strongly influenced by genetics, but it has been difficult to identify allelic variation in humans underlying abuse liability. Natural allelic variation in the human population is likely to largely consist of mild change-of-function alleles of important genes that contribute to the physiological effects of ethanol. Only certain genes and pathways can be modified to affect alcohol response phenotypes, and only certain types of alleles are likely to be maintained in a natural population. Studies of laboratory-induced mutations in animal models have yielded a good understanding of the neuropharmacology of ethanol, but much remains to be learned about relevant natural allelic variation that impacts alcohol use phenotypes in humans. We aim to advance the understanding of the natural allelic variation that exists and the pathways that can be modulated in wild populations to modify the neurobiological response to alcohol in wild isolates of C. elegans. We examined four French wild strains (JU1511, JU1931, JU1941, JU1926), of which two were isolated from a fruit (apple) and two from a plant (hogweed), for three acute ethanol response behaviors. We tested low dose locomotor activation, high dose initial sensitivity, and high dose induction of acute functional tolerance. We found that there is substantial phenotypic variation between the four strains for these phenotypes, strongly suggesting that there is natural allelic variation that modulates acute ethanol responses. To identify the causal variants, we are performing quantitative trait locus mapping using a panel of approximately 200 recombinant inbred lines (RILs) derived from these four wild parent strains. The phenotypes vary continuously among the RILs tested. We have found transgressive RILs for each of the three behavioral phenotypes, indicating that there are multiple alleles in the population that can assort independently. Finally, at least some of the alleles influence specific aspects of the behavioral response to ethanol, because there is low correlation between the phenotypes in the RILs. Together, our observations indicate that there is extensive natural genetic variation underlying independent aspects of the ethanol response behaviors in C. elegans. We will map these to loci and aim to confirm causal alleles using genome editing.

De Stasio E et al. (1994) Worm Breeder's Gazette "Mutagenesis of C. elegans Using N-ethyl-N-nitrosourea."

De Stasio E, Stanislaus D, Lephoto C

[Worm Breeder's Gazette, 1994]

Mutagenesis of C. elegans using N-ethyl-N-nitrosourea Elizabeth De Stasio, Dinesh Stanislaus and Catherine Lephoto. Department of Biology, Lawrence University, Appleton, Wl 54911

Goodwin EB et al. (1994) Worm Breeder's Gazette "The laf-1 Gene Functions in the 3'UTR-Mediated Translational Repression of the Sex Determination Gene, tra-2"

Kimble JE, Goodwin EB

[Worm Breeder's Gazette, 1994]

The laf-l Gene Functions in the 3'UTR-mediated Translational Repression of the Sex Determination Gene, tra-2. Elizabeth Goodwin# and Judith Kimble University of Wisconsin, Madison, WI. # Dept. of CMS Biology, Northwestern Univ. Medical School, Chicago Ill.

(2023) Development "An interview with Aimee Jaramillo-Lambert."

[Development, 2023]

Aimee Jaramillo-Lambert is currently an Assistant Professor at the University of Delaware. Aimee was awarded the Society for Developmental Biology 2023 Elizabeth D. Hay New Investigator Award in recognition of her outstanding research in developmental biology during the early stages of her independent career. We caught up with Aimee over a video call to talk about her research into sexual reproduction in Caenorhabditis elegans, the importance of mentorship, and what drives her work in diversity, equity and inclusion.

Hsiao, Andrew et al. (2021) International Worm Meeting "SWI/SNF chromatin remodeling complexes regulate the expression of innate immunity genes and modulate acute responses to alcohol."

Mathies, Laura, Davies, Andrew, Bettinger, Jill, Hsiao, Andrew, Quamme, Elizabeth, Lindsay, Jonathan

[International Worm Meeting, 2021]

Alcohol use disorder is a significant social problem. Despite intense study, we have only a limited understanding of the direct and indirect targets of ethanol, leading to difficulty in generating effective pharmacological interventions. We use C. elegans to model the acute effects of ethanol on neuronal function in order to identify molecular targets of ethanol and determine the mechanisms underlying the development of tolerance to those effects. We have found that SWI/SNF genes are associated with alcohol dependence in human populations and that SWI/SNF complexes are important for behavioral responses to alcohol in C. elegans. SWI/SNF chromatin remodeling complexes consist of multiple subunits that can be combined to generate functionally and molecularly distinct chromatin remodelers. Two major subfamilies of SWI/SNF are BAF (Brm/Brg1-associated factors) and PBAF (Polybromo-BAF) and these complexes affect different aspects of the acute response to alcohol in worms. The initial response to alcohol has at least two components, initial sensitivity and the development of acute functional tolerance (AFT). We found that BAF complexes regulate initial sensitivity to ethanol, while PBAF complexes are required in neurons for the development of AFT (Mathies et al, 2015). We focus here on the role of PBAF in AFT. Using neuronal rescue of swsn-9 (a PBAF subunit) and a temperature-sensitive allele of swsn-1 (a core subunit of BAF and PBAF), we identified 603 genes whose expression is regulated by PBAF in neurons and in adults (Mathies et al., 2020). Among the transcriptional targets of PBAF were genes involved in the innate immune response. Innate immunity is regulated by several conserved signaling pathways, including the p38 MAPK, ERK MAPK, TGFB, and insulin pathways, as well as the stress response. We asked if any of these pathways regulates acute behavioral responses to alcohol by testing representative genes in each pathway. We found strong evidence for the involvement of the p38 and ERK MAPK pathways in the development of AFT. We are currently examining genes that are regulated by both SWI/SNF and PMK-1 (p38 MAPK) to identify downstream mediators of AFT.

Silverman PH (1999) Science "C. elegans as a model."

Silverman PH

[Science, 1999]

Elizabeth Pennisi, in her excellent commentary "Worming secrets from the C. elegans" (News Focus, 11 Dec 1998, p.1972), states that "The first person to sense that the worm might take on such a prominent role in biology was molecular biologist Sydney Brenner." I am sure that Brenner would wish to acknowledge the role that Ellsworth C. Dougherty played in this matter. Dougherty originally described in 1949, "[a] new species of the free-living nematode genus Rhabditis of interest in comparative physiology and genetics".

Torti, Sebastian et al. (2021) International Worm Meeting "Investigating the overlap between on-food exploration behavior and off-food behavioral responses to alcohol"

Torti, Sebastian, Quamme, Elizabeth, Hsiao, Andrew, Bettinger, Jill, Davies, Andrew, Mathies, Laura

[International Worm Meeting, 2021]

Variation in genes that modulate the acute level of response to alcohol are predicted to play a significant role in the predisposition of individuals to develop alcohol use disorder (AUD) over their lifetime. We are using C. elegans to identify genes that are important in mediating behavioral responses to ethanol with the goal of highlighting candidate genes that are likely to play similar roles in humans. In a forward genetic screen for mutations that have reduced sensitivity to the effects of ethanol on the speed of locomotion in the absence of food, we identified a nonsense mutation in the nep-2 gene, an ortholog of the mammalian metalloprotease neprilysin. In C. elegans, nep-2 has been shown to be important in regulating the impact of population density on olfactory adaptation behavior (Yamada et al. 2010). Our working hypothesis is that NEP-2 cleaves a peptide that acts to suppress an effect of ethanol on locomotion speed, and that in the absence of NEP-2 function, that peptide accumulates and counters the effect of ethanol to a greater extent, leading to reduced ethanol sensitivity. While investigating neuropeptide receptors (NRs) for a role in mediating this nep-2 effect on ethanol sensitivity, we examined a potential link between ethanol sensitivity and roaming and dwelling behavioral states. In an exploration assay, which serves as a proxy measure for the degree of roaming, we found that nep-2 mutants have increased exploration measures relative to wild-type controls, while mutants for two NRs (pdfr-1 and npr-25) each have reduced exploration on food and are hypersensitive to ethanol off food. This suggests that regulation of exploration-related behavioral states may also impact sensitivity to ethanol. We are now testing the degree of correlation between exploration and sensitivity to ethanol by performing exploration assays on mutants that alter behavioral responses to ethanol, and by examining the ethanol sensitivity of mutants that are known to alter the frequencies of roaming and dwelling. These experiments will enable us to classify genes and pathways that are important in mediating behavioral responses to ethanol.

Vande Waa EA (1991) Parasitol Today "Chemotherapy of filariases."

Vande Waa EA

[Parasitol Today, 1991]

The filarial parasites that affect humans most seriously include Onchocerca volvulus, Wuchereria bancrofti, Brugia malayi and Loa loa. In general, these species cause disease that is debilitating long before it is fatal, producing clinical manifestations such as general malaise, pruritus and lichenification of the skin, lymphangitis, elephantiasis and blindness(1). As a result, infection with any one of these organisms is physically, as well as economically, devastating. Currently, the pharmacological armamentarium with which to treat filarial infections is very limited and many of the drugs that are known to be efficacious against these worms may produce side effects that cause extreme discomfort. Here, Elizabeth Vande Waa describes the quest for new chemotherapeutic approaches for the treatment of filarial infections.

Crossen, Tyler et al. (2021) International Worm Meeting "Lipidomic analysis of the effects of exposure to ethanol on worms."

Mathies, Laura, Bettinger, Jill, Kumar, Naren, Crossen, Tyler, Wijesinghe, Dayanjan, Davies, Andrew, Contaifer, Daniel, Quamme, Elizabeth

[International Worm Meeting, 2021]

The use of alcohol causes important physiological changes that contribute to the development of alcohol use disorder (AUD). These ethanol-induced changes are multifaceted and are incompletely characterized. In particular, the effects of ethanol on the composition and quantity of lipid species is under studied. We are particularly interested in lipidomic effects because several lines of evidence in our laboratory have implicated lipid metabolism in acute ethanol responses in worms. We therefore performed an unbiased lipidomic analysis of wild-type animals exposed for 16 hours to an intoxicating dose of ethanol. We found that several different lipid classes responded to the ethanol exposure, and that prominent among these was an increase in several different lipids containing odd-chain fatty acids (OCFA). C. elegans derive most OCFAs from their bacterial diet. In our ethanol exposure paradigm, the animals were exposed while feeding on OP50, so we examined if the bacteria were responding to the ethanol treatment. We found that the bacteria did not change their OCFA levels in response to ethanol, suggesting that the ethanol-induced increase in OCFA was due to effects on the worms themselves. We also observed that the long chain polyunsaturated omega-3 fatty acid eicosapentaenoic acid (EPA) appeared to be moved from its storage form in triacylglycerides to other phospholipid species, suggesting that it was mobilized in response to ethanol exposure. We have previously shown that EPA is required for normal acute behavioral responses to ethanol (Raabe et al., 2014), and that dietary EPA modulates ethanol response behaviors in mice (Wolstenholme et al., 2018). Both OCFA and EPA have been implicated in modulating membrane fluidity; this suggests a model in which animals modify their lipidomes in response to ethanol, perhaps to regulate the function of membrane proteins that are targets of ethanol. Together, these results lend new insight into the role of lipids in the response to ethanol exposure and provide a rich dataset for future studies.

Sterken, Mark et al. (2021) International Worm Meeting "Transcriptional analysis of the response of C. elegans to ethanol exposure"

van Wijk, Marijke, Davies, Andrew, Sterken, Mark, Kammenga, Jan, Bettinger, Jill, Carnell, Lucinda, Quamme, Elizabeth, Mathies, Laura, Riksen, Joost

[International Worm Meeting, 2021]

Ethanol consumption induces differential gene expression that are likely to at least partially underlie the progression to alcohol use disorder. We use C. elegans to study the effects of ethanol on nervous system function. To understand the gene expression dynamics that occur upon ethanol exposure, we conducted a time series experiment exposing C. elegans to a behaviorally intoxicating dose of ethanol for 30, 60, 120, and 480 minutes. The number of differentially expressed genes was positively correlated with exposure duration. We used K- means clustering to cluster genes based on expression over time and divided them in 5 distinct clusters. Gene ontology analysis showed enrichment for processes known to be involved in ethanol responses, for example: drug metabolism - cytochrome P450 and metabolic pathways. Furthermore, at eight hours of exposure several genes that are known to be involved in physiological response to ethanol were down regulated; some of those genes have been previously identified as direct ethanol targets, including the gene encoding the BK SLO-1 channel, the synaptic protein-encoding unc-13 gene, as well as genes involved in GABA signaling, suggesting a simple model in which downregulation of direct ethanol targets could decrease the depressing effects of ethanol and could contribute to the development of tolerance to ethanol. Our exposure paradigm delivered ethanol in the absence of food, and we found that eight hours of food deprivation had a significant impact on overall gene expression as assessed by principal component analysis and transcriptional development analysis. Interestingly, ethanol was able to partially rescue the effect of food deprivation at eight hours, extending previous observations that C. elegans can use ethanol as a calorie source. This timeseries captured gene expression dynamics in response to ethanol over time and will be used as a resource for our follow up studies, including investigating natural variation in gene expression in response to ethanol.