Saxena, Ayush Shekhar et al. (2019) International Worm Meeting "Evolution of noise and phenotypic plasticity with relaxed selection in Caenorhabditis elegans."

Laird, Anne, Dembek, Joanna, Baer, Charles, Snyder, Michael, Saxena, Ayush Shekhar

[International Worm Meeting, 2019]

The "Fluctuation-Dissipation Relation" of statistical physics shows that the random fluctuation ("noise") experienced by certain kinds of physical systems at thermodynamic equilibrium is expected to be proportional to the response of the system to perturbation. Biological organisms are a special kind of physical system, and it has been posited that the Fluctuation-Dissipation Relation applies to many aspects of biological systems. Specifically, it has been suggested that the phenotypic variance exhibited among a genetically uniform set of individuals raised in a uniform environment (= "noise") should be proportional to the consistent variation in phenotype between sets of genetically identical individuals raised in different environments (= "phenotypic plasticity"). That is, the FDR applied to biological systems predicts that phenotypic noise within a uniform environment should be proportional to phenotypic plasticity between environments. If so, it implies a fundamental tradeoff in fitness components, such that genotypes that are more capable of responding to systematic environmental variation - which is adaptive, all else equal - will experience more random phenotypic variation even in the optimal environment - which is maladaptive, all else equal. If indeed there is a fundamental tradeoff between noise and plasticity, at an evolutionary optimum, there are three possible outcomes: (1) natural selection may favor greater plasticity at the cost of additional noise; (2) robustness ("quiet") may be favored at the cost of restricted plasticity, or (3, and least likely), both plasticity and robustness may be optimal. Under this scenario, the cumulative effects of deleterious mutations will cause the system to evolve away from the selective optimum, thereby illuminating the pattern of natural selection. Alternatively, if the relationship between noise and plasticity is an emergent property of the system, or if there is no relationship, the relationship will remain unchanged, or will change at random. To test these competing hypotheses, we assayed fitness, and 15 other fitness-proximal traits, in four environments, in ~130 mutation accumulation (MA) lines of C. elegans, generated from two starting ancestors, N2 and PB306. We observe that both noise and plasticity in relative fitness increase with mutation accumulation. In addition, the mutational variance (VM) of noise is on the same order of magnitude as VM for trait means. However, we did not find covariance between noise and plasticity, which suggests a role for natural selection in shaping this relationship in the wild. In addition, we find that mutational heritability of mean trait value and noise in trait value are highly correlated across the 16 traits we measured.

Chan S et al. (1991) International C. elegans Meeting "SEEKING UNC-40."

Culotti JG, Su M-W, Chan S, Hedgecock EM

[International C. elegans Meeting, 1991]

unc-40 is required with unc-6 to guide ventral migrations on the nematode epidermis (Hedgecock et al., Neuron 4, 61-85, 1990). We have positioned unc-40 genetically by 3-factor crosses with dpy-5 and bli-4 as flanking markers and we have isolated 5 new alleles of unc-40 (2 spontaneous, 2 gamma, and 1 EMS) making a total of 12. DNAs from cosmids covering this region (obtained from Alan Coulson and John Sulston) are being used to probe DNA and RNA from the mutants and DNA from strains carrying duplications that break to either side of unc-40 (obtained from Anne Rose's laboratory). We are also injecting cosmid DNAs into gonads to look for rescue by germline transformation. The brood sizes of various unc-40 alleles are very small, so we have resorted to injecting the wild type in order to create a series of transformed lines, each carrying an extrachromosomal array of a different cosmid. Each array will be passed into appropriately marked unc-40 animals to ask if any can rescue the mutant phenotype. Mosaic experiments are also underway to determine whether unc-40 acts in migrating cells.

Shi, Cheng et al. (2019) International Worm Meeting "Insulin-like peptides and the mTOR-TFEB pathway protect C. elegans hermaphrodites from Mating-induced Death."

Shi, Cheng, Murphy, Coleen

[International Worm Meeting, 2019]

C. elegans lifespan is shortened by mating, but must be delayed long enough for successful reproduction. Susceptibility to brief mating-induced death increases with age; surprisingly, this is not due to declining health, but to loss of protection upon self-sperm depletion. Self-sperm maintains expression of a DAF-2 insulin-like antagonist, INS-37, which promotes the nuclear localization of HLH-30/TFEB, a pro-longevity regulator. Mating induces the agonist INS-8, promoting HLH-30 nuclear exit and subsequent death. In opposition to the protective role of HLH-30 and DAF-16/FOXO, TOR/LET-363 and the IIS-regulated Zn-finger transcription factor PQM-1 promote seminal-fluid-induced killing. Self-sperm maintenance of nuclear HLH-30/TFEB allows hermaphrodites to resist mating-induced death, increasing the chances that mothers will survive through reproduction. The hijacking of the IIS pathway by males is combated by the mother's expression of an insulin antagonist that keeps her healthy through the activity of pro-longevity factors, as long as she has her own sperm to utilize. ** If possible, I would prefer that this abstract please be considered with the abstract submitted by Lauren N. Booth, Travis J. Maures, Robin W. Yeo, and Anne Brunet ("Self-sperm induce resistance to the detrimental effects of sexual encounters with males in hermaphroditic nematodes").

Verster, Adrian et al. (2009) International Worm Meeting "Examining Changes in Gene Function in Caenorhabditis nematodes using RNAi libraries."

Felix, Marie-Anne, Verster, Adrian, Mckay, Sheldon, Ramani, Arun

[International Worm Meeting, 2009]

Gene functions change throughout evolutionary history and understanding how this occurs is a key goal of molecular evolutionary biology. To date researchers have systematically looked at changes in gene function by comparing loss of function phenotypes in orthologs from different model organisms, such as S. cerevisiae and C. elegans. However, since there has been such a large evolutionary divergence between these organisms their body plans are so different and many phenotypes are impossible to compare. It is much more practical to compare phenotypes from organisms with similar body plans and ecological niches. Here we use Caenorhabditis nematodes to systematically look at changes in gene function through evolution because loss of function phenotypes map easily between species. In order to address this problem we are building an RNAi library for C. briggsae to look for changes in gene phenotype from those that were observed in C. elegans. Genome scale RNAi has been successfully used in C. elegans and thus we are going to use it in C. briggsae. In order to do this we take advantage of the sid-2 transgenic C. briggsae line (gratefully contributed by Marie-Anne Felix''s group) which has been shown to uptake RNAi by feeding. We will present preliminary screening data from the C. briggsae RNAi library and showcase the changes in gene function we have found so far.

Jorgensen EM et al. (1995) International C. elegans Meeting "CLONING AND CHARACTERIZATION OF THE SYNAPTIC FUNCTION MUTANT RIC-1."

Harris TW, Jorgensen EM

[International C. elegans Meeting, 1995]

We have taken a genetic approach to identify molecules involved in neurotransmission. We identified several previously unidentified genes in a behavioral screen for mutants defective in synaptic function. Among these was ric-5(n1337). When touched on the head, ric-5(n1337) mutants move backwards in a jerky, uncoordinated fashion, and frequently coil. ric-5 maps to the cluster of LG III. To obtain putative null alleles of ric-5, a noncomplementation screen was conducted to generate additional alleles. Approximately 7000 EMS mutagenized genomes were screened, and we recovered 7 new alleles of ric-5. We mapped the position of ric-5 to the right of mec-14 and to the left of lin-39. Several other mutations resembling the ric-5 phenotype mapped to this same region. osm-13(n1602) (Josh Kaplan and Anne Hart, personal communication) mapped to this interval and we demonstrated that n1337 and n1602 failed to complement. Carl Johnson mapped ric-1(e239) to this interval, and we demonstrated that e239 and n1337 failed to complement. In light of these data, ric-5 has now been renamed ric-1. Jim Rand's laboratory has isolated 19 mutations in ric-1, bringing the total number of ric-1 alleles to 28. Microinjection of cosmid pools spanning this region weakly rescue the coiling phenotype of ric-1.

Maureen M Barr (2001) International C. elegans Meeting "Lov neurotransmission"

Maureen M Barr

[International C. elegans Meeting, 2001]

The nervous system of the adult C. elegans male possesses 381 neurons to the hermaphrodite's 302. These additional sex-specific neurons are required for male mating behaviors, namely, response to hermaphrodite contact, backing, turning, location of vulva (Lov), spicule insertion, and sperm transfer. We are specifically studying Lov behavior at the cellular, genetic, and molecular levels. The HOA and HOB hook neurons are required for Lov behavior (1) and the putative sensory receptor lov-1 is expressed in HOB (2). How does signaling initiated by the LOV-1 receptor culminate in Lov behavior? We are interested in identifying the neurotransmitters and neuropeptides used by the HOA and HOB mechano- and chemosensory neurons, respectively (3). Anne Hart and Arif Nathoo have identified 21 putative n europeptide like protein ( nlp ) genes in C. elegans and made transcriptional GFP fusions (4) which we have screened for expression in the adult male tail. An nlp-8::gfp transcriptional fusion is expressed uniformly throughout the HOB neuron. Expression is also observed in other non-sex, non-stage specific cells. We have constructed a full length nlp-8::gfp translational fusion and observed expression only in HOB, suggesting nlp-8 may be a Lov neuropeptide. We are exploring the role of nlp-8 in Lov behavior using genetic and molecular approaches. Liu, K. S. and P. W. Sternberg. 1995. Neuron 14:79-89. Barr, M. M. and P. W. Sternberg. 1999. Nature 401: 386-389. Sulston, J. E. et al. 1980. Developmental Biology 78:542-576. Nathoo, A., R. Moeller, and A. Hart. 1999. International Worm Meeting abstract 621.

Parry D et al. (1997) International C. elegans Meeting "Closing In On unc-34"

Forrester WC, Parry D, Garriga G

[International C. elegans Meeting, 1997]

We are interested in cloning unc-34. Mutations in unc-34 disrupt both cell and growth cone migrations. Laird Bloom split unc-34 and unc-60 and found unc-34 mapped to the left of cosmid R09A1, on VL. Kim McKim observed that DNA from sDf39/sDf34 animals failed to hybridize to cosmid C26D7. sDf34 fails to complement unc-34, and sDf39 fails to complement markers to the left of unc-34, suggesting C26D7 is left of unc-34. Our attempts to rescue unc-34 with either cosmids or YACs in the area have failed. Our current goal is to narrow the physical region where unc-34 may lie, in order to be more focussed in future rescue attempts. We are concentrating our efforts on three approaches. First, we are trying to construct a chromosome with a marker linked to the left of unc-34. Since the previous left end point was determined by deficiency mapping, and deficiencies can be complex, we want to split a marker off from the left of unc-34. The Baillie lab has isolated several lethals which have been placed to the left of unc-34 by deficiency mapping. Our efforts to link one of these lethals to unc-34 by recombination have failed, so we are mutagenizing unc-34 mutant chromosomes and screening for linked lethals. Once we find a lethal linked to the left of unc-34, we will use it to map unc-34 relative to polymorphisms in the region. We will also map polymorphisms to the right with any lethals we find which lie between unc-34 and unc-60. Our second approach is to generate Tc alleles of unc-34 in a non-complementation screen. If we find transposon-induced alleles, we hope to clone unc-34 relatively quickly using PCR with Tc-specific primers. We are also mapping deficiency endpoints in the region, with the hope that we may find more proximal endpoints.

Conroy, Brian et al. (2013) International Worm Meeting "The neuronal basis of food choice behavior in Caenorhabditis elegans."

Morabe, Maria, Chambers, Melissa, Conroy, Brian, Macfarlane, Rachel, Haynes, Lillian, Glater, Elizabeth

[International Worm Meeting, 2013]

Caenorhabditis elegans uses chemosensation to distinguish among various species of bacteria, their major food source (Ha et al., 2010; Shtonda and Avery, 2006). Although the neurons required for the detection of specific food-odors have been well-defined (Bargmann, 2006), less is known about the sensory circuits underlying the discrimination among the mixtures of odors released by bacteria. We plan to examine the neural machinery underlying bacterial preference among a diverse set of bacterial species. Does bacterial choice use one common neuronal mechanism or a diversity of mechanisms depending on the bacteria? Do some bacterial choices involve a single sensory neuron and others involve multiple sensory neurons? To address these questions, we are testing the food preferences of C. elegans for bacteria found in their natural habitats (kindly provided by Marie-Anne Felix, Institut Jacques Monod, Paris, France). We have found that C. elegans strongly prefers the odors of Providencia sp., Alcaligenes sp., and Flavobacteria sp., to Escherichia coli HB101, a commonly used food source for C. elegans. We have identified that the olfactory neuron AWC is necessary for this preference. We intend to test whether other amphid sensory neurons are also necessary for bacterial preference. In the future we will extend our analysis to other bacterial species to determine the diversity of the underlying neuronal mechanisms. Bargmann, C.I. (2006). http://www.wormbook.org. Ha, H.I., Hendricks, M., Shen, Y., Gabel, C.V., Fang-Yen, C., Qin, Y., Colon-Ramos, D., Shen, K., Samuel, A.D., and Zhang, Y. (2010). Neuron 68, 1173-1186. Shtonda, B.B., and Avery, L. (2006). J Exp Biol 209, 89-102.

Paolo Moroni et al. (2006) European Worm Meeting "Characterization of C.elegans NuRD Complexes"

Karin Brunschwig, Fritz Muller, Myriam Passannante, Vanessa Cerantola, Paolo Moroni, Anne-Laure Chanez

[European Worm Meeting, 2006]

Paolo Moroni, Myriam Passannante, Karin Brunschwig, Anne-Laure Chanez, Vanessa Cerantola and Fritz Mller. The NuRD (nucleosome remodeling and histone deacetylase) complex is thought to be involved in the establishment of repressive chromatin structures during development and in the negative control of gene expression. In vertebrates, this complex comprises at least seven polypeptides, including the SWI2/SNF2 helicase/ATPase Mi-2, the histone deacetylases HDAC1/2, the histone-binding proteins RbAp46/48, the metastasis-associated proteins MTA1/2, the methyl-CpG binding protein MBD3 and the potent transcriptional repressor p66. Orthologues of these NuRD subunits are also encoded by the genome of C.elegans, among them the two Mi-2 homologues LET-418 and CHD-3.. Mutations in let-418 show a pleiotropic phenotype, including sterility and larval arrest (von Zelewsky and al., 2000), whereas chd-3 mutants exhibit no obvious defects. However, a null mutation of chd-3 enhances the let-418 phenotype. This suggests that the two proteins have partially redundant functions during development (von Zelewsky et al., 2000).. To find proteins interacting with LET-418 and CHD-3 and to characterize putative NuRD complexes in C.elegans, we take different approaches. We use standard biochemical techniques, such as co-immunoprecipitation, tandem affinity purification (TAP) and yeast two-hybrid screens.. Our preliminary data suggest that LET-418 and CHD-3 may not be interchangeable members of the same complex, but rather are part of different NuRD or NuRD-like complexes.. von Zelewsky and al., Development 127: 5277-5284 (2000)

Chung, Kevin et al. (2015) International Worm Meeting "The neuronal basis of bacterial food odor preference."

Kan, Emily, Glater, Elizabeth, Haynes, Lillian, Ota, Ryan, Chambers, Melissa, Chung, Kevin

[International Worm Meeting, 2015]

Caenorhabditis elegans uses chemosensation to distinguish among various species of bacteria, their major food source 1-3. Although the neurons required for the detection of specific food-odors have been well-defined, less is known about the sensory circuits underlying the discrimination among the mixtures of odors released by different kinds of bacteria. We are examining the neural machinery underlying bacterial preference among a diverse set of bacterial species. Specifically, we are testing the food preferences of C. elegans for bacteria found in their natural habitats (kindly provided by Marie-Anne Felix, Institute of Biology of Ecole Normale Superieure, Paris, France). We have found that C. elegans prefers the odors of most species tested over E. coli. We have identified that the olfactory neuron AWC is involved in many preferences. We also find that some bacterial choices involve multiple sensory neurons with opposing roles. For example, in one choice in which wild-type animals prefer Providencia sp. (JUb39) over E. coli, the AWC neuron appears to be involved in increased preference for Providencia and the AWA neuron in increased preference for E. coli. In the future we will extend our analysis to additional bacterial species to determine the diversity of the underlying neuronal mechanisms.1. Harris, G. et al. Dissecting the Signaling Mechanisms Underlying Recognition and Preference of Food Odors. J. Neurosci. 34, 9389-9403 (2014).2. Ha, H. et al. Functional Organization of a Neural Network for Aversive Olfactory Learning in Caenorhabditis elegans. Neuron 68, 1173-1186 (2010).3. Shtonda, B. B. & Avery, L. Dietary choice behavior in Caenorhabditis elegans. J. Exp. Biol. 209, 89-102 (2006).