Lesley MacNeil et al. (2008) C.elegans Neuronal Development Meeting "UNC-129 Alters the Response to UNC-6/Netrin by Regulating the Decision Between UNC-40 Dependent and Independent UNC-5 Signaling"

Jeffrey Wrana, Lesley MacNeil, William Hardy, Joseph Culotti

[C.elegans Neuronal Development Meeting, 2008]

UNC-129 is a TGF-beta family ligand that regulates ventral to dorsal migration of commissural motor axons in C. elegans. Mutations in unc-129 result in motoraxons that do not accomplish normal ventral to dorsal migration, but instead deviate from their proper course. Genetic evidence demonstrates that UNC-129 does not function as other TGF-beta family ligands, through the classical type I and type II serine/threonine kinase receptors, but instead regulates axon guidance through a novel signaling pathway. Genetic interactions between null alleles of unc-129 and unc-5, unc-40 and unc-6 revealed that unc-129 acts within the UNC-5 signaling pathway to regulate axon guidance, cell migration and patterning of the male tail. Analysis of unc-40 and unc-129 compound null mutants demonstrates that UNC-129 acts specifically to promote UNC-5+UNC-40 signaling. In contrast, overexpression studies using ectopically expressed UNC-129 suggest that UNC-129 acts to inhibit UNC-40 independent UNC-5 signaling. Together, these data suggest a model where UNC-129 regulates the decision between UNC-40 dependent and independent UNC-5 signaling. The result of this, for cells and axons migrating along the ventral-dorsal axis, is to increase the sensitivity of cells and axons to decreasing levels of UNC-6/Netrin by switching from UNC-5 signaling to UNC-5+UNC-40 signaling.

Haight M et al. (1975) Cryobiology "Freeze-thaw survival of the free-living nematode Caenorhabditis briggsae."

Pasternak JJ, Haight M, Frey H, Frim J

[Cryobiology, 1975]

For a long time nematodes have been noted for their ability to survive drastic environmental challenges such as severe dessication and low temperatures. The properties that enable a fully differentiated, postembyronic multicellular organism to recover from such treatment are of interest. In addition to the intrinsic need to examine the cryobiological behavior of such a hardy organism, the value of the nematode in other research areas has been described. Therefore, a reliable and successful method for long-term preservation would be an advantage for maintaining diverse stock cultures....

Montarry, Josselin et al. (2014) Evolutionary Biology of Caenorhabditis and Other Nematodes "Heterozygote deficits in cyst forming plant parasitic nematodes: disentangling consanguinity and Wahlund effect"

Montarry, Josselin, Fournet, Sylvain, Gracianne, Cecile, Pierre-Loup, Jan, Grenier, Eric, Petit, Eric, Bardou-Valette, Sylvie

[Evolutionary Biology of Caenorhabditis and Other Nematodes, 2014]

To date the reproduction mode of plant parasitic nematodes has been poorly investigated in details though it will strongly impact the evolutionary potential of these pests and in particular their ability to adapt more or less rapidly to plant resistances. Molecular data and population genetic analyses are powerful tools to investigate the evolutionary and ecologically processes that impact populations. Deviations of genotypic frequencies from Hardy- Weinberg equilibrium (HWE) expectations could reveal important aspects of the biology of populations. Deviations from HWE due to heterozygote deficits (FIS > 0) have been recorded for few animal parasite species, and interestingly also for two cyst forming plant parasitic nematode species, Globodera pallida and Heterodera shachtii. However, it has never been determined whether the observed deficits were due (i) to the presence of null alleles, (ii) to a high level of consanguinity and/or (iii) to a genetic structuration at a sub-population scale (Wahlund effect). Indeed, the limited active dispersal of larvae from their cysts, which possibly favors mating between siblings or genetic structuration at a small scale, could be responsible for the strong heterozygote deficit observed in cyst forming nematode populations. The aim of the present work was to disentangle, using recently developed microsatellite markers, consanguinity and Wahlund effect in natural populations of three economically important cyst nematode species: G. pallida, G. tabacum and H. shachtii, which attack potato, tobacco and sugar beet, respectively. The obtained results will be discussed regarding the distinctive biological features of those species (e.g. host range, number of generation per year) and of the sampled populations (e.g. coming from different environments including the cultivated and wild compartments).Keywords: consanguinity, Hardy-Weinberg equilibrium, heterozygote deficit, microsatellite, nematode, null allele, Wahlund effect

Bruce Wightman (2005) International Worm Meeting "MUTANT SCREENING AND GENE MAPPING IN FIFTEEN WEEKS"

Bruce Wightman

[International Worm Meeting, 2005]

I favor semester-long projects in my intermediate level undergraduate Genetics lab course. This approach helps to give students a stake in whats happening in the lab, instead of having them walk in each week and ask the pedagogical equivalent of Whats for dinner tonight? One project is a semester-long Drosophila population genetics lab that allows them to evaluate forces the disrupt Hardy-Weinberg equilibrium. The other major project is a C. elegans F2 EMS screen for mutations that cause visible phenotypes, followed by a single round of STS mapping. Most students are able to generate some linkage data from this approach. In some cases, they can even postulate potential gene identities from their linkage data after consulting Wormbase. Using this approach, students are able to gain some experience that is open-ended and genuinely focused on actual research strategies within the confines of a traditional 3-hour per week teaching laboratory. I will bring protocols for any who are interested.

Kearn J et al. (2013) Invert Neurosci "Meeting report: 2012 Caenorhabditis elegans Neurobiology meeting, EMBL Advanced Training Centre, Germany."

Dalliere N, Dillon J, Kearn J

[Invert Neurosci, 2013]

Some of the finest minds in the field of Caenorhabditis elegans neurobiology were brought together from 14 June to 17 June 2012 in the small, quaint and picturesque German city of Heidelberg for the biannual C. elegans neurobiology conference. Held at the EMBL Advanced Training Centre and wonderfully organised by Diah Yulianti, Jean-Louis Bessereau, Gert Jansen and William Schafer, the meeting contained 62 verbal presentations and hundreds of posters that were displayed around the double-helical walkways that looped throughout the conference centre. Presentations on recent advances in microfluidics, cell ablation and targeted gene expression exemplified the strengths of C. elegans as a model organism, with these advances allowing detailed high-throughput analysis and study. Interesting behaviours that were previously poorly characterised were widely discussed, as were the advantages of C. elegans as a model for neurodevelopment and neurodegeneration and the investigation of neuropeptide function. The examples discussed in this meeting report seek to illustrate the breadth and depth of presentations given on these recurring topics.

Fisher MC et al. (1998) Proc Biol Sci "The population genetic structure of the facultatively sexual parasitic nematode Strongyloides ratti in wild rats."

Fisher MC, Viney ME

[Proc Biol Sci, 1998]

We have investigated the population genetic structure of the parasitic nematode Strongyloides ratti in wild rats. In the UK, S. ratti reproduces predominantly by mitotic parthenogenesis, with sexual forms present at a rate of less than 1%. S. ratti was found to be a prevalent parasite and substantial genetic diversity was detected. Most rats were infected with a genotypic mixture of parasites. A hierarchical analysis of the genetic variation found in S. ratti sampled across Britain and Germany showed that 73.3% was explained by variation between parasites within individual hosts and 25.3% by variation between rats within sample sites. Only a small proportion (1.4%) of the total genetic variation was attributable to genetic subdivision between sample sites, suggesting that there is substantial gene flow between these sites. Most parasites sampled were found to exist in Hardy-Weinberg equilibrium and this population genetic structure is discussed in view of the virtual absence of sexual reproduction.

Sela N et al. (2008) Biol Direct "Transduplication resulted in the incorporation of two protein-coding sequences into the turmoil-1 transposable element of C. elegans."

Ast G, Makalowski W, Sela N, Pupko T, Stern A

[Biol Direct, 2008]

ABSTRACT: Transposable elements may acquire unrelated gene fragments into their sequences in a process called transduplication. Transduplication of protein-coding genes is common in plants, but is unknown of in animals. Here, we report that the Turmoil-1 transposable element in C. elegans has incorporated two protein-coding sequences into its inverted terminal repeat (ITR) sequences. The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene. We further report that an open reading frame specific to C. elegans may have been created as a result of a Turmoil-1 insertion. Mutations at the 5'' splice site of this open reading frame may have reactivated the transduplicated RRM motif. Reviewers: This article was reviewed by Dan Graur and William Martin. For the full reviews, please go to the Reviewers'' Reports section.

Stephan R Goodwin et al. (2003) International Worm Meeting "A C. elegans population genetics lab."

Stephan R Goodwin, Scott E Baird

[International Worm Meeting, 2003]

Studying evolution with an investigative approach in introductory biology is difficult due to time, space and monetary limitations. Caenorhabditis elegans, however, provides an effective model organism to look at natural selection and population genetics within a manageable timeframe. We have developed a single-day C. elegans laboratory exercise to illustrate natural selection. In this exercise, mixed populations of fog-2 and dpy-11 fog-2 worms were initiated at four-day intervals starting thirty days prior to the scheduled laboratory date. Populations were bleached and L1 larvae collected five days prior to the lab. Starvation-arrest L1s were fed two days prior to the lab. Thus, students were required to score Dpy and wild-type phenotypes in synchronous populations of young adults. From frequencies of Dpy worms present at each time point students were required to determine dpy-11 (e224) allelic frequencies and observe the increase in calculated heterozygousity via the Hardy-Weinberg law. We found the optimal way to initiate populations was with 18 gravid dpy11 fog-2 females and two gravid fog-2 females. Starting with such populations we observed an exponential decay of the dpy11 (e224) frequency that reached zero by the last time point.

Bourguinat C et al. (2006) Parasitology "Genetic polymorphism of the beta-tubulin gene of Onchocerca volvulus in ivermectin naive patients from Cameroon, and its relationship with fertility of the worms."

Pion SD, Boussinesq M, Gardon-Wendel N, Prichard RK, Kamgno J, Duke BO, Gardon J, Bourguinat C

[Parasitology, 2006]

Observations of low response of patients infected with Onchocerca volvulus to ivermectin suggest that the parasite may be under a selection process toward potential resistance. To limit the extension of this phenomenon, it is crucial to characterize the genes of O. volvulus that are involved. For this, O. volvulus adult worms collected before the introduction of ivermectin in an onchocerciasis endemic area of central Cameroon were genotyped for beta-tubulin. To derive a baseline to investigate the selective pressure of ivermectin, we analysed (1) the frequency distribution of the beta-tubulin alleles, and (2) the relationship between the different beta-tubulin related genotypes and the fertility status of the female worms. The frequency of allele b of the beta-tubulin gene was very low, as it was observed in West Africa. We observed a deficit of heterozygous female worms leading to Hardy Weinberg disequilibrium, which might be explained by a shorter life-span of these worms compared to the homozygous worms. Unexpectedly, our results also show that the heterozygous female worms were much less fertile than the homozygotes: more than two thirds of the homozygotes were fertile, whereas only 37% of the heterozygotes were fertile. These results will be further considered when analysing post-treatment data.

Fonte V et al. (2002) Proc Natl Acad Sci U S A "Interaction of intracellular beta amyloid peptide with chaperone proteins."

Taft A, Link CD, Friedman D, Fonte V, Fluet A, Kapulkin V

[Proc Natl Acad Sci U S A, 2002]

Communicated by William B. Wood, University of Colorado, Boulder, CO, May 24, 2002 (received for review March 22, 2002) Expression of the human ss amyloid peptide (Ass) in transgenic Caenorhabditis elegans animals can lead to the formation of intracellular immunoreactive deposits as well as the formation of intracellular amyloid. We have used this model to identify proteins that interact with intracellular Ass in vivo. Mass spectrometry analysis of proteins that specifically coimmunoprecipitate with Ass has identified six likely chaperone proteins: two members of the HSP70 family, three alphaB-crystallin-related small heat shock proteins (HSP-16s), and a putative ortholog of a mammalian small glutamine-rich tetratricopeptide repeat-containing protein proposed to regulate HSP70 function. Quantitative reverse transcription--PCR analysis shows that the small heat shock proteins are also transcriptionally induced by Ass expression. Immunohistochemistry demonstrates that HSP-16 protein closely colocalizes with intracellular Ass in this model. Transgenic animals expressing a nonaggregating Ass variant, a single-chain Ass dimer, show an altered pattern of coimmunoprecipitating proteins and an altered cellular distribution of HSP-16. Double-stranded RNA inhibition of R05F9.10, the putative C. elegans ortholog of the human small glutamine-rich tetratricopeptide-repeat-containing protein (SGT), results in suppression of toxicity associated with Ass expression. These results suggest that chaperone function can play a role in modulating intracellular Ass metabolism and toxicity.