Howells RE et al. (1991) Parasitol Today "Caenorhabditis elegans: A model for parasitic nematodes."

Johnstone IL, Howells RE

[Parasitol Today, 1991]

The free-living nematode Caenorhabditis elegans offers many advantages as an experimental system and extensive similarities in overall structure and development exist between it and parasitic nematodes. The purpose of the meeting held at Broadway, 17-20 February 1991, with the financial support of the Wellcome Trust, was to stimulate interaction between schools of nematologists.

Avila, Felipe et al. (2009) International Worm Meeting "Genome-wide analysis of the chromosomal distribution of transposable elements in C. elegans."

Avila, Felipe, Feschotte, Cedric, Broadway, Brad, Pires-daSilva, Andre

[International Worm Meeting, 2009]

The C. elegans genome is around 100 Mb long, and about 12% of it is derived from transposable elements (TEs). There has been a recent growing interest in the possible role of mobile elements in genome regulation and evolutionary plasticity; however, there has been no comprehensive, detailed analysis of the overall C. elegans TE distribution and their possible functional roles. In this study, we analyzed the intra and inter-chromosomal distribution pattern of all 156 TE families known in C. elegans. We found that more than 12% of these families are over-represented on the X chromosome. The many unique features of the X chromosome, such as dosage compensation, inactivation in the germline and low gene density make it an interesting case study for possible biological relevance of the skewed distribution of these families. Cele45, for example, is a family of Short Interspersed Elements (SINEs) which has 3 times more insertions on the X chromosome than expected. Conversely, we found that 10% of the TE families are completely absent in this chromosome, despite their high copy number (more than 500 copies) in the autosomes. Cele4, a DNA transposon, has 831 copies in the C. elegans genome and none of those are found on the X chromosome. It has been previously shown that the distribution pattern of DNA transposons is positively correlated with high recombination rates, which usually occur in the chromosomal arms. In the X chromosome, however, recombination rates are uniform across its length. Intriguingly, we found that the distribution pattern of most of the families (51%) of both DNA and RNA transposons does not correlate with recombination rate on the X chromosome. Thus, other factors must account for the preferential accumulation of these TEs on the arms of the X chromosome.

Schein JE et al. (1996) West Coast Worm Meeting "CONSTRUCTION AND UTILIZATION OF THE CHROMOSOME IV COSMID TRANSGENIC LIBRARY"

Schein JE, Rose AM, Baillie DL, Franz NW, Janke DL

[West Coast Worm Meeting, 1996]

Construction of a chromosome IV cosmid transgenic library of C. elegans strains carrying sequenced cosmids in extrachromosomal arrays has begun as part of our labs' collaboration with the Genome Sequencing Consortium (see abstract by D. Janke et al.). There are 20 chromosome IV cosmids available in transgenic strains at the time of this writing, and we estimate a total of 40-50 will be available to the community by the end of July. In order to enhance the utility of this library, we are also using these strains to localize approximately 50 essential gene mutations, previously identified in the Baillie lab, to cosmids by way of transgenic rescue experiments (for results of similar efforts on chromosomes III and V, see abstracts by Nigel O'Neil et al., Helen Stewart et al., and Brad Barbazuk et al.). Correlation of the genetic and physical maps in this manner will facilitate the selection of candidate cosmids for use in further rescue experiments, and thereby increase the speed with which the connection between genetic mutations and DNA sequence is made. Currently these rescue experiments are focused in the sDf2 region, in particular in the lin-3 - let-60 interval, which contains 13 essential gene mutations and 21 overlapping cosmids. The two genes bracketing this interval, lin-3 and let-60(ras), were previously placed on the physical map by others. To date, two additional essential genes have been positioned to cosmids on the physical map; let-70(ubc2) (in collaboration with Mei Zhen and Peter Candido) and let-64. It is anticipated that by the time of the meeting several additional mutations will have been positioned to cosmids. This work is being funded by a grant from the Canadian Genome and Associated Technologies Program to Ann Rose and David Baillie.

Riddle DL et al. (1984) Worm Breeder's Gazette "Caenorhabditis elegans from Adelaide soil."

Riddle DL, Kirtland SK, Bird AF

[Worm Breeder's Gazette, 1984]

Soil samples (200-300 gms) from the Adelaide area were collected from leafy compost, cultivated garden plots, orchards and open areas at 17 locations. The soil samples were placed over funnel collectors in a misting chamber overnight and the filtrate was collected in 90 ml test tubes. Most of the water was removed by suction, and the remainder was allowed to settle in a conical centrifuge tube. This sediment of worms and debris about 0.1-0.2 ml in volume was transferred to the surface of a 8.5 cm diameter NGM agar petri plate spread with E. coli. After three days incubation at room temperature (24 C), worms which grew and reproduced on the E. coli were selected. Worms morphologically similar to C. elegans were transferred to fresh plates at hourly intervals, 2 to 3 times in succession. These repeated transfers removed contaminating soil microbes. The worms were cloned, and those animals capable of self-fertilization were then mated with C. elegans N2 males. Generally, no more than four clones were made from any soil sample, and two hermaphrodite progeny from each clone were mated with four males on a petri plate. When F1 males (usually 30-60) issued from such a cross, the maternal clone was tentatively identified as C. elegans. Final confirmation was obtained by backcrossing the F1 hybrid males with hermaphrodites from the cloned soil isolate. The appearance of F1 males in this latter cross demonstrated that the hybrid males were fertile. The 17 soil samples produced four new C. elegans isolates: one from Alan Bird's garden (AB1), one from the Australian Wine Research Institute grounds (AB2), and two from Waite Agricultural Research Institute nursery plots. The samples containing C. elegans were moist, well-aerated, and near the surface where decaying vegetable matter provided ground cover. We conclude from these preliminary results that C. elegans may be widespread in the Adelaide area, and perhaps in other areas of Australia as well. Stocks of AB1, AB2, AB3 and AB4 were repeatedly sub-cloned to ensure that a genetically true- breeding stock was obtained. To determine the male bursa morphology exhibited by an Australian C. elegans strain, spontaneous males were picked from a large population (approx. 50,000 worms) of the AB1 clone, and subsequently propagated by mating with AB1 hermaphrodites. The pattern of bursal rays was identical to that previously described for C. elegans isolates from England and France. Southern hybridizations with AB strain genomic DNA using a Tc1 probe (kindly provided by Brad Rosensweig) showed that each of the AB strains is of the low copy number (N2) type, although the AB1 pattern differs slightly from the other three, and they all differ slightly from N2.