Nguyen, Anh Quynh et al. (2009) International Worm Meeting "THE GENETICS OF DEET RESISTANCE IN Caenorhabditis elegans."

Limes, Julia, Freedman, Matt, Douglas, Alfred, Nguyen, Anh Quynh, Hartman, Phil, Copeland, Heather

[International Worm Meeting, 2009]

The molecular mechanism(s) by which DEET (N,N-diethyl-m-toluamide) acts as an insect "repellent" has not been resolved. Using forward genetic screens in Caenorhabditis elegans, we have isolated five DEET-resistant mutants (der-1) after EMS mutagenesis of DEET-sensitive N2. Two are allelic and have been mapped between 2.4 mu and 2.9 mu on linkage group (LG) IV. Specifically, 3F (factor) cross data between two markers unc-5 (1.78 mu) and egl-19 (3.34 mu) on LGIV showed that 11/22 (50%) Egl-19 recombinants were DEET-resistant and 11/22 (50%) were DEET sensitive for allele hf175. In case of allele hf176, the data were 19/32 (59%) and 13/32 (41%), respectively. In addition, all Lin-33 recombinants from the 3F cross between two references unc-5 (1.78 mu) and lin-33 (2.55 mu) showed DEET sensitivity in both hf175 and hf176. Several additional 3F crosses are in various stages of completion. Interestingly, wild-type strains CB4856, AB1, and AB2 have been shown to be DEET resistant relative to the wild-type strains N2 and CB4852, which are both DEET sensitive. These findings suggest that DEET-resistance may be more common than we originally expected. Successful cloning of the der-1 gene is an important step not only to elucidate the mechanism of DEET action but may prove useful in designing the next generation of chemicals that helps reducing insect-borne-diseases.

AI Vaz Gomes et al. (1999) International C. elegans Meeting "Elucidating the function of a novel DNA polymerase"

EL Sonnhammer, AI Vaz Gomes

[International C. elegans Meeting, 1999]

The C. elegans genomic sequence has revealed the presence of a gene (W03A3.2) homologous to bacterial DNA polymerase I (PolA). This family was previously thought to be specific for bacteria but other genes clearly belonging to this family are now found in many eukaryotes, including Drosophila, maize, Plasmodium, Arabidopsis, mouse, and human. No such gene is present in yeast however. It thus appears that this is an ancient family of DNA polymerase which has been lost in some species. Functional studies on the Drosophila homolog (mus-308) have indicated a role in repair of crosslinked DNA (1). Both the Drosophila and Arabidopsis homologs posses an N-terminal helicase domain. Intriguingly, a similar helicase domain is encoded upstream of W03A3.2, denoted W03A3.3. They were not predicted as one gene by Genefinder because another gene, ceh-10, lies in between these domains the opposite strand. We are currently addressing the following questions: 1. Are the helicase and polymerase domains parts of one gene in the worm too? 2. What is the function of this or these genes? 3. What is the evolutionary relationship between the PolA-like sequences in different species? Indications that the domains may be transcribed separately include: Attempted RT-PCR from the helicase to the polymerase domain yielded no product; RNAi knockdown of the helicase domain induced degeneration of embryos "in utero" while targeting the polymerase domain gave no phenotype at all. Indications for one single gene include: No RT-PCR product was yielded between SL1 or SL2 and the polymerase domain; The fly and plant homologs have the two domains on a single protein chain. On the other hand, a recently cloned human homolog, named Pol eta (3), lacks the helicase domain. We have showed that the helicase domain is expressed (transspliced to SL1) and has a function essential for development. More work is needed to understand the polymerase domain. These studies are being pursued by simultaneous targeting, Northern analysis, RACE-PCR, expression studies, and antibody raising for immunodetection. 1. Harris et al (1996) Mol.Cell.Biol. 16, 5764-5771 2. Sonnhammer & Wootton (1997) Curr.Biol. 7, R463-465 3. Sharief, Ropp and Copeland, unpublished

Yoko Honda et al. (2005) International Worm Meeting "Study of space-flight effect on the aging of C. elegans in the International C. elegans Experiment(ICE)-First"

Shuji Honda, Noriaki Ishioka, Yoko Honda

[International Worm Meeting, 2005]

As exposures to the space environment become longer, information regarding the effects on biological aging will become important. We have not yet fully clarified aging processes in space environments. The aging process and lifespan are affected by various kinds of environmental factors including oxygen concentration (1), temperature and radiation. The aging phenomena that we usually see occur under certain conditions on the ground. Space environments differ from ground environments especially with regard to the radiation spectrum and gravity. We participated in the International C. elegans Experiment(ICE)First that examined the effects of a 10-day space flight on the nematode C. elegans. C. elegans has frequently been used for study of aging because of its short lifespan. Recently, Morley et al. reported that Huntington's-like polyglutamine (polyQ)-repeat proteins expressed in the muscle of C. elegans form aggregates as the animals age, and that this aggregation is delayed in long-lived mutants(2). We measured the polyQ aggregates in these nematodes after space flight as an aging marker. Herndon et al. showed that the sarcomere orientation in the body-wall muscle becomes disorderly as the animals age(3). We also observed the sarcomere orientation in the body-wall muscle of these nematodes after space flight as another aging marker. Acknowledgement: We thank Dr. R. L. Morimoto (Northwestern University) for providing us polyQ-YFP C. elegans strains. We also thank CGC for other strains. ICE-First was mainly conducted by the French Space Agency (CNES), with support of the European Space Agency and the Space Research Organization of the Netherlands. We are grateful to Dr. Michel Viso (CNES), Dr. K. Kuriyama (JAXA) and Dr. A. Higashitani (Tohoku University) for their support and suggestion for our experiment. References: 1) Honda S., Ishii N, Suzuki K, Matsuo M. J Gerontol. 48:B57-61. 1993 2) James F. Morley, Heather R. Brignull, Jill J. Weyers, and Richard I. Morimoto. Proc. Natl. Acad. Sci. USA, 99: 10417-10422. 2002 3) Herndon LA, Schmeissner PJ, Dudaronek JM, Brown PA, Listner KM, Sakano Y, Paupard MC, Hall DH, Driscoll M. Nature. 419:808-814. 2002