Nathalie Pujol et al. (2001) Worm Breeder's Gazette "Ver midi IV"

Jonathan Ewbank, Nathalie Pujol

[Worm Breeder's Gazette, 2001]

La quatrieme reunion annuelle des equipes francaises ayant un interet pour C. elegans se tiendra le Vendredi 23 fevrier 2001 a Luminy, Marseille. Contact: pujol@ibdm.univ-mrs.fr ewbank@ciml.univ-mrs.fr

Zarkower D et al. (1994) Worm Breeder's Gazette "mab-3 YAC Rescue"

De Bono M, Hodgkin JA, Zarkower D

[Worm Breeder's Gazette, 1994]

mab-3 YAC rescue David Zarkower, Mario de Bono, and Jonathan Hodgkin MRC Laboratory of Molecular Biology, Cambridge, England

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

Plasterk RHA et al. (1994) Worm Breeder's Gazette "Reverse Genetics Using Transposon Tc1: A Progress Report"

Plasterk RHA, de Vroomen M

[Worm Breeder's Gazette, 1994]

Reverse genetics using transposon Tcl: A progress report Ronald H.A. Plasterk, Marianne de Vroomen, the Netherlands Cancer Institute, Division of Molecular Biology, Plesmanlaan 121,1066 CX Amsterdam, the Netherlands, fax + 31 20 6172625, phone +31 20 5122081, E-mail RPLAS@NKI.NL

(1976) Worm Breeder's Gazette

[Worm Breeder's Gazette, 1976]

Robert Wyman (Department of Biology, Yale University) reports that Theodore Bullock (University of California at San Diego, La Jolla, California) has isolated a 4.1-meter long nematode from a 3.8-meter whale. The specimen is preserved, and Dr. Bullock is searching for a taxonomist interested in taking the beast. Want Ad: Does anyone know a way to cause a large population of males to release their sperm into the medium? CONTEST REMINDER: Don t forget that bottle of champagne from S. Ward and D. Hirsh promised to whoever scores the most progeny from a single hermaphrodite (see Newsletter, Vol. 1, # 2 for details). Deadline for submission of entries to either judge is February 23rd.

Naclerio G et al. (1991) Worm Breeder's Gazette "Descriptive analysis of some repeated elements"

Naclerio G, La Volpe A

[Worm Breeder's Gazette, 1991]

In the last few years our group has been studying the large scale organization of repetitive DNA sequences. We are characterizing six repetitive DNA families interspersed in the genome of C. elegans: RcA1, RcD1, Rc35, RcC9, RcS5 and RcB1. We presented in CSH 1989 the physical distribution of our repeated elements in the genome. Some of these families (RcD1, Rc35, RcC9, see also La Volpe et al. (1988) Nucl. Acids Res. 16, 82138231 ) are characterized by the presence of short tandemly repeated modules (satellite-like repetitive DNA). We compared the sequence of three elements belonging to the RcA1 family (Copy number: 161) localized on chromosomes I, II and V respectively; each member is 118 bp in length and the core region of 46bp is perfectly conserved between the three. The elements of the RcD1 family (present at 138 loci in the genome) are characterized by tandem repetitions of an extremely conserved 15bp unit. The Rc35 is another satellite-like family localized at 76 loci; the tandem repeated module is 35bp long. The RcC9 family described in La Volpe et al. (1988) has the basic tandemly repeated unit of 10bp (and the same consensus of the Heat-Shock Element) and is present at 84 positions on C. elegans genome. An element belonging to the RcB1 family (copy number 57) is characterized by the presence of direct terminal repeats of 64 bp. We observed that, although they are present along all the chromosomes, these families are not distributed completely randomly, but there are some regions of accumulation of elements belonging to different repetitive families, some of which we analyzed in detail by sequencing. There is an inverse correlation between the presence of repetitive regions along the chromosomes and the frequency of recombination, that recalls the repression of legitimate recombination near the centromeres of Drosophila and Schizosaccharomyces pombe.

Tabuse Y et al. (1994) Worm Breeder's Gazette "The tpa-1 Gene Encodes Two Forms of a Protein Kinase C Homolog."

Tabuse Y, Miwa J, Sano T

[Worm Breeder's Gazette, 1994]

The tpa-l gene encodes two forms of a protein kinase C homolog Yo Tabuse, Tohru Sano, and Johji Miwa NEC Fundamental Research Laboratories, Tsukuba, Ibaraki 305, Japan. Typical tumor-promoting phorbol esters (TPA and PDD) cause severe disorders in the growth and behavior of C. elegans. The tpa-l gene, which mediates the action of the agents, encodes a protein kinase C (PKC) homolog. The tpa-l gene consists of eleven exons and spans a genomic region of about 20 kb. Two mRNA species, 2.8 kb and 2.4 kb, are transcribed from the tpa-l locus and both are trans-spliced to SL1. The former contains all the eleven exons and codes for a protein of 80 kDa (TPA-lA); on the other hand, the latter lacks the first four exons and codes for a 65-kDa protein (TPA-lB) without some 150 amino acids at the amino-terminal portion of TPA-lA (Sano et al. C. elegans meeting '93, see Figure). In order to examine whether the two mRNA species are produced by two alternate promoters, we have tried to rescue a TPA- resistant mutant strain, MJ563, by microinjecting genomic fragments of the tpa-l gene, variously lacking its 5' region. Microinjection of plasmid constructs of these fragments showed rescuing activity. One of these rescuing constTucts, pSK14, contained a fragment covering only about 1 kb upstream of the 5th exon through the end of tpa-l, indicating that there is another promoter within 1 kb upstream of the 5th exon for the 2.4-kb mRNA. The result also shows that TPA-lB is sufficient to confer TPA-sensitivity on C. elegans. We are now examining tissue expression patterns of the 2.8-kb and 2.4-kb mRNAs with tpa-l-lacZ fusions to ask whether there are any differences in the distribution of these two mRNAs.

Weisblat D et al. (1975) Worm Breeder's Gazette "Electrophysiological Studies of Ascaris Muscle"

Byerly L, Russell RL, Weisblat D

[Worm Breeder's Gazette, 1975]

Using Ascaris as a model system, we are studying ionic mechanisms of the spontaneous electrical activity in nematode somatic muscle. The fast spike potentials appear to be Ca+2 mediated; their amplitude depends on the external Ca+2 concentration, they are TTX insensitive, they persist when Na+ is replaced by Tris+, choline+, or Cs+, and they are blocked by Co+2 and La+3. When the normal solution is replaced by one containing 11 mM Ba+2 and 0.15 mM Ca+2 as the only divalent cations, the slow waves underlying the normal spike activity appear to increase dramatically in amplitude and duration; spike activity gradually disappears. The duration and amplitude of the slow waves at steady state under these conditions increase with Ba+2 concentration, reaching values of 1-2 minutes and 50-60 mV, respectively, in 26 mM Ba+2. These results and others lead us to conclude that the slow waves are also Ca+2 mediated. The muscles are depolarized by 0.1 mM ouabain, suggesting some involvement of an electrogenic pump in maintaining the membrane potential. TEA, in concentrations as low as 1 mM, has pronounced effects on the spontaneous myogenic activity, consistent with the effects observed when TEA is injected iontophoretically into C. elegans.

Mueller F et al. (1991) Worm Breeder's Gazette "CHROMATIN ELIMINATION IN ASCARIS LUMBRICOIDES TAKES PLACE WITHIN A SHORT, PRECISELY DEFINED CHROMOSOMAL DNA SEGMENT"

Tobler H, Mueller F, Wicky C

[Worm Breeder's Gazette, 1991]

The chromosomes of Ascaris lumbricoides undergo chromatin diminution in those cells destined to form the somatic lineages of the animal. During this process, the heterochromatic ends of the chromosomes break off and eventually degrade in the cytoplasm. The shortened chromosomes are stable, suggesting that elimination is accompanied by a de novo formation of telomeres. In order to test this hypothesis, we decided to analyze the structure of the somatic telomeres of A. lumbricoides. Bal 31 experiments revealed that they carry multiple copies of the tandemly repeated hexamer TTAGGC, a sequence that is similar to those found at the chromosomal ends of vertebrates and some lower eukaryotes. Since we expected the regions flanking the somatic telomeres to be involved in the elimination process, we designed a cloning strategy for their isolation from the genome of A. lumbricoides. One of the positive clones obtained (pTel 1) was analyzed in detail. By sequencing we found pTel 1 to carry 27 perfect repeats of the hexamer TTAGGC, oriented 5' to 3' towards the end of the fragment. Thus, the orientation of the G-rich strand corresponds exactly to the defined orientation of eukaryotic telomeric repeats. The subtelomeric DNA sequences of pTel 1 are unique and therefore specific for a single somatic telomere. The corresponding region within the germ line genome is located at an internal chromosomal site rather than on a telomere. Elimination, however, does not take place merely at the locus cloned in pTel 1, but also at many more sites, all of them being scattered throughout a 3 kb long specific DNA segment within this region. The nucleotide sequence of this DNA segment is very AT-rich, but so far no specific elimination signals could be identified. Comparison of pTel 1 with the corresponding germ line sequences shows that chromosomal fragmentation is followed by the addition of tandem arrays of the telomeric repeating units TTAGGC, which are not present on the germ line chromosome at this site. The interesting question, whether this de novo formation of telomeres is carried out by the action of a telomere terminal transferase activity, is currently investigated in our laboratory.

Donkin SG et al. (1993) Worm Breeder's Gazette "C. elegans as a Soil Toxicity Test Organism"

Donkin SG, Dusenbery DB

[Worm Breeder's Gazette, 1993]

We have developed a new procedure for recovering nematodes from soils in an efficient and non-destructive manner, which has permitted the development of a short-term soil toxicity test using nematodes as toxicity indicators. The procedure involves gentle centrifugation through a colloidal silica suspension (Ludox AM or Ludox HS-40, both available from E. I. Du Pont de Nemours & Co., Wilmington, DE), which allows the soil to settle out while floating the nematodes on top of the suspension. The nematodes are recovered with great efficiency (~90%) and are unharmed by the recovery process. Short-term lethality tests (24-hour exposure) were performed with several metals (Cd, Cu, Hg, Ni, Pb, and Zn) in several different characterized soils, and replicable results were obtained, allowing concentration-response curves to be generated and LC(50)s to be estimated. It was found that the presence of soil generally decreased the toxicity of the metals to nematodes when compared to tests done without soil present. This is presumably due to the sorption of the metal ions to the soil particles, which lowered their availability to the nematodes. Comparison between nematode lethality results and data published for earthworms exposed to metals in soil revealed that, in most cases, the nematode is at least as sensitive as the earthworm in terms of its response to toxic metals in soil. The earthworm test, which is currently the standard animal soil toxicity test, has the disadvantage of taking two weeks to perform, while the nematode test can be done in 24 hours. Some correlations between soil or metal properties and the resulting lethal effects were obtained, while other properties showed no significant correlation with toxic effects. This suggests that, as other studies have indicated, the bioavailability of metals in soils cannot be reliably predicted by considering only a few sample conditions. Soils are complex and heterogeneous systems, and there are many physico-chemical processes that may occur within them and which may influence the resulting bioavailability of a contaminant. The C. elegans soil toxicity test may provide the means to identify some of the more important environmental characteristics that influence contaminant bioavailability.