Waterston RH et al. (1979) International C. elegans Meeting "organization of the unc-54 myosin heavy chain gene."

Smith KC, Waterston RH

[International C. elegans Meeting, 1979]

Kravtsov, V. et al. (2013) International Worm Meeting "The effects of aging on dendritic plasticity and PVD-FLP branch coexistence."

Podbilewicz, B., Oren-Suissa, M., Kravtsov, V.

[International Worm Meeting, 2013]

Self-avoidance, tiling and coexistence are the main mechanisms that enable the best dendritic coverage. C. elegans undergoes aging-associated changes that ultimately lead to decreased functionality of the organism, including its neurological functions. Recent research has shown that the nervous system of C. elegans undergoes changes and alterations during aging including dendritic morphology (Tank et al., 2011). We study dendritic plasticity, aging and spatial dendritic organization of two highly arborized mechanoreceptors in C. elegans, PVD and FLP (Oren-Suissa et al., 2010). PVD dendrites of L4s and young adults show regenerative ability following dendrotomy (laser induced severing of dendrites). Our working hypothesis is that in older ages this ability to regenerate is compromised. Previous studies and our preliminary results indicate that PVD and FLP do not overlap in larval stages (Smith et al., 2010). In addition, dendrites within each bilateral PVD do not overlap through a self-avoidance mechanism (Smith et al., 2012). We found that (1) the coverage fields of the PVD and FLP overlap in adult worms, which indicates coexistence and not tiling. This overlap increases as the worm ages. (2) PVDs show aberrant arborization at the age of 9 days of adulthood. (3) Dramatic increase in self-avoidance defects as animals age. In humans many neurodegenerative diseases as well as generalized cognitive decline are associated with age, aberrant arborization or both (e.g. autism and Alzheimer's disease). However our understanding of how these disorders are triggered and aggravated is scarce. Our research provides an insight into the aging and regeneration process of individual neurons. Oren-Suissa, M., et al. (2010). Science 328, 1285-1288. Smith, C.J. et al. (2010). Developmental Biology 345, 18-33. Smith, C.J., et al. (2012). Nature Neuroscience 15, 731-737. Tank, E.M.H. et al. (2011). Journal of Neuroscience 31, 9279-9288.

Denich KTR et al. (1983) International C. elegans Meeting "ts embryonic mutants: the Gottingen set revisited."

Cassada RC, Smith KC, Isnenghi E, Schierenberg E, Denich KTR

[International C. elegans Meeting, 1983]

Isnenghi E et al. (1981) International C. elegans Meeting "maternal and other modes of expression and time of temperature sensitivity of genes affecting embryogenesis."

Radnia K, Cassada RC, Isnenghi E, Von Ehrenstein G, Smith KC

[International C. elegans Meeting, 1981]

Isnenghi E et al. (1981) International C. elegans Meeting "genetic dissection of embryogenesis in Caenorhabditis elegans."

Radnia K, Isnenghi E, Von Ehrenstein G, Denich KTR, Cassada RC, Schierenberg E, Smith KC

[International C. elegans Meeting, 1981]

Pourkarimi, Ehsan et al. (2015) International Worm Meeting "Epigenetic program of DNA replication."

Whitehouse, Iestyn, Pourkarimi, Ehsan, Bellush, James

[International Worm Meeting, 2015]

In eukaryotes, multiple replication origins initiate DNA synthesis bidirectionally. Half of the genome is duplicated discontinuously on the lagging strand in the form of Okazaki Fragments (OFs). Previously we have purified and sequenced OFs from S. cerevisiae, and have demonstrated their utility in mapping genome wide DNA replication patterns (1,2). Despite many years of research, the precise location efficiency and abundance of replication origins in metazoa remains elusive. Here we capture and sequence OFs from C. elegans and generate a genome wide map of DNA replication.We use a DNA ligation compromised genetic background and purify single stranded OFs from developing embryos. Aligning sequence reads of OFs to the C. elegans genome reveals a characteristic strand bias at specific sites that are approximately 50-100 Kb apart. The complementary enrichment of Okazaki fragments to either the Watson or Crick strands is the hallmark of a replication origin. Additionally we have found that origins of replication in C. elegans are correlated with transcriptionally active regions of chromatin. Using the histone modification data set of modENCODE we found a strong association between replication start sites and acetylation of Histone H3 lysine 27 (H3K27ac). Acetylation of H3K27 is a chromatin mark characteristic of gene enhancer elements. Finally, we show that a partial depletion of CBP/P300 the sole histone H3 acetyltransferase (HAT) responsible for H3K27 acetylation has a profound effect on DNA replication. Our data indicate that the DNA replication program is likely plastic and is matched with the transcriptional program. Ultimately our data show, both DNA replication and gene transcription are likely regulated by similar epigenetic processes. 1. Intrinsic coupling of lagging-strand synthesis to chromatin assemblyDuncan J. Smith& Iestyn Whitehouse. Nature, 20122. Quantitative, genome-wide analysis of eukaryotic replication initiation and termination.McGuffee SR, Smith DJ, Whitehouse I. Mol Cell, 2013.

Lee DG et al. (1997) International C. elegans Meeting "THE EXPRESSION PATTERN OF CALETICULIN, A HIGH AFFINITY CALCIUM BINDING PROTEIN"

Ahnn JH, Lee DG

[International C. elegans Meeting, 1997]

In C. elegans, a homologue of mammalian calreticulins was cloned and sequenced (M. Smith, DNA seq. 2: 235-40). This gene is composed of three exons and two introns and encodes a protein of 395 amino acid residues including an N-terminal signal sequence. The C-terminus contains an ER retention signal HDEL preceded by a polyacidic region similar to the mammalian calreticulins. Especially, the sequence displays 61% homology to mouse calreticulin, increasing up to 82% in the proline-rich region. This gene was designated as crt-1 and mapped to the left end of chromosome V of the physical map. To observe the expression pattern of calreticulin in some tissues of C. elegans, we are currently constructing a genomic clone fused with GFP reporter, which will be injected into an animal to obtain transgenic lines. At the same time, a cDNA clone obtained by PCR will be used for over expression in E. coli to produce antibodies.

Mary Kosinski et al. (2001) International C. elegans Meeting "Control of Oocyte Meiotic Maturation and Gonadal Sheath Cell Contraction by MSP Signaling"

Mary Kosinski, David Greenstein, Michael A Miller

[International C. elegans Meeting, 2001]

Oocyte meiotic maturation and ovulation are essential biological processes required for reproduction. During meiotic maturation, C. elegan s oocytes undergo nuclear envelope breakdown, cortical rearrangement, and meiotic spindle assembly in an assembly-line-like fashion. Recently we found that the major sperm cytoskeletal protein (MSP) is the sperm derived signal that induces both oocyte meiotic maturation and gonadal sheath cell contraction (1). Many questions remain about this newly discovered signaling pathway. For example, how does a cytoskeletal protein function as a signaling molecule? How does MSP signal two distinct responses? To examine MSP signaling in vivo , we analyzed extracellular MSP localization. Previous studies reported the intracellular localization of MSP during spermatogenesis (2). We stained mated fog-2 females with anti-peptide antibodies generated to the N- and C- terminal regions of MSP, as well as previously described antibodies (2). In addition to intracellular staining within spermatozoa, we observed an extracellular MSP gradient, with the highest levels of MSP within the spermatheca and lower levels in the proximal gonad arm. The average extent of the observable MSP gradient is approximately 30 m m. Detection of this extracellular MSP gradient is dependent on the number of sperm present and their position in the spermatheca. By mating females with Mr. Vigorous, we have been able to detect the MSP gradient extending as far as 90 m m. These data suggest that a fraction of MSP is released from sperm in vivo, and the most proximal oocyte receives the highest concentration of released MSP. MSP is a bipartite signal: MSP (106-126) is sufficient to promote gonadal sheath cell contraction, and MSP (1-106) is sufficient to promote oocyte maturation (1). In solution MSP exists as a dimer (3). To determine if dimerization is necessary for signaling, we injected dimerization mutants (4) into females and measured oocyte maturation and sheath cell contraction rates. The dimerization mutants tested signal both oocyte maturation and gonadal sheath cell contraction at rates similar to wild-type MSP. To further identify regions responsible for promoting oocyte maturation and gonadal sheath cell contraction, we tested whether Ascaris suum MSP could signal in C. elegans . Ascaris MSP shares about 80% identity with C. elegans MSP at the amino acid level. Our results indicate that Ascaris MSP can signal maturation and sheath cell contraction in C. elegans at rates comparable to C. elegans MSP. We are currently targeting regions for deletion experiments that are conserved between both C. elegans and Ascaris . 1. Miller et al. (2001). Science 291:2144-2147 2. Ward & Klass. (1982). Dev. Bio. 92:203-208 3. Haaf et al.(1996). J. Mol. Biol. 260:251-260 4. Smith & Ward. (1998). J. Mol. Biol. 279:605-619 We would like to thank T. Roberts and P. Griffin for Ascaris clones and S. Ward and H. Smith for dimerization mutants and antibodies.

Haag, E.S. et al. (2019) International Worm Meeting "Evolution of sex ratio through gene loss."

Haag, E.S., Yin, D.

[International Worm Meeting, 2019]

The maintenance of males at intermediate frequencies is an important evolutionary problem. Several species of Caenorhabditis nematodes have evolved the androdioecious mating system, where selfing hermaphrodites and males coexist. They reproduce mostly through self-fertilization, but can also outcross. While selfing produces XX hermaphrodites, cross-fertilization produces 50% XO male progeny. Thus, male mating success dictates the sex ratio [1]. Here, we focus on the contribution of the male secreted short (mss) gene family to male mating success, sex ratio, and population growth. The mss family is essential for full sperm competitiveness in gonochoristic species, but has been lost in parallel in androdioecious species [2]. Using a transgene to restore mss function to the androdioecious C. briggsae, we examined how mating system and population subdivision influence the fitness of the mss+ genotype. Consistent with theoretical expectations, mss+ is sufficient to increase male frequency and depress population growth in genetically homogenous androdioecious populations. When mss+ and mss-null (i.e. wild-type) genotypes compete, mss+ is positively selected in both mixed-mating and strictly outcrossing situations, though more strongly in the latter. Thus, while sexual mode alone affects the fitness of mss+, it is insufficient to explain its parallel loss. We propose that the lack of inbreeding depression [3] and the strong subdivision that characterize natural Caenorhabditis populations [4] impose selection on sex ratio that makes loss of mss adaptive. By reducing, but not completely eliminating outcrossing, loss of the mss genes tunes the sex ratio to its new optimum after self-fertility is established. 1. Stewart AD, Phillips PC (2002) Genetics 160: 975 2. Yin et al. (2018) Science 359: 55 3. Dolgin et al. (2007) Evolution 61: 1339 4. Kiontke KC, et al. (2011) BMC Evol Biol 11: 339

Stephan Steidl et al. (2002) West Coast Worm Meeting "Mutations of a glutamate-gated chloride channel in C. elegans affect short-term memory in an ISI dependant manner, long-term memory, and foraging behaviour"

Nicholas Dube, Catharine H Rankin, Stephan Steidl, Jacqueline K Rose

[West Coast Worm Meeting, 2002]

avr-14 encodes a alpha-type subunit of a glutamate-gated chloride channel (GluCls) in C. elegans, a receptor closely related to mammalian glycine-gated chloride channels. avr-14 is expressed on the glutamatergic sensory neurons of the tap-withdrawal response (TWR) (Dent et al., 2000). avr-14 receptors may act as an autoreceptors regulating sensory neuron activity. Worms with a functional null mutation of avr-14 were tested for short-term habituation of the TWR at 10s, 30s, 45s, and 60 s ISI's. It was found that worms with this mutation showed more rapid habituation than wild-type at shorter ISIs (10s and 30s) while showing habituation similar to wild-type at long ISIs (45s and 60s). Worms with the same mutation appear to show enhanced long-term memory compared to wild-type controls. avr-14 mutants show an increased frequency and a decreased magnitude of spontaneous reversals compared to wild-type. Spontaneous reversals are thought to be part of a foraging strategy in C. elegans. The hypothesis that the altered frequency and magnitude of spontaneous reversal would affect foraging strategy was supported by an experiment is which avr-14 worms were unable to negotiate a simple copper sulfate maze to reach food while wild-type worms easily reached the food. Reference: Dent, J.A., Smith, M.M., Vassilatis, D.K., & Avery, L. (2000). The genetics of Ivermectin resistance in Caenorhabditis elegans. Proc. Natl. Acad. Sci. (USA), 97, 2674-2679. Supported by: An NSERC PGS A to SS and an NSERC operating grant to CHR.