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Riddle DL, Blumenthal T, Meyer BJ, et al., editors. C. elegans II. 2nd edition. Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 1997.

Cover of C. elegans II

C. elegans II. 2nd edition.

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Section IIOrigins of the Model

The potential value of Rhabditis species for genetic research was pointed out by Dougherty and Calhoun (1948). C. elegans was initially described and named Rhabditis elegans by Maupas (1900); it was subsequently placed in the subgenus Caenorhabditis by Osche (1952) and then raised to generic status by Dougherty (1955). The name is a blend of Greek and Latin (Caeno, recent; rhabditis, rod; elegans, nice). Two strains have historical importance. One strain, Bergerac, was collected from the soil in France by Victor Nigon of the Université de Lyon (Nigon 1949), and the other strain, Bristol, was isolated by L.N. Staniland (National Agricultural Advisory Service, London) from mushroom compost near Bristol, England (Nicholas et al. 1959). At high inoculum, C. elegans and its associated bacteria are reported to cause losses in mushroom yield and quality (Grewal 1991).

Using the Bergerac isolate, Nigon (1949) observed a haploid chromosome number of six and documented the two modes of reproduction, by selfing and by crossing with males. Males of the Bristol strain were obtained in Nigon's laboratory for taxonomic classification, and the arrangement and morphology of the caudal papillae, or “rays,” in the male copulatory bursa (Emmons and Sternberg, this volume) were found to be the same as that already described for C. elegans var. Bergerac (Nigon and Dougherty 1949). Bristol males were then successfully crossed with hermaphrodites of the French strain.

Ellsworth Dougherty brought C. elegans to his laboratory at the Kaiser Foundation Research Institute in Richmond, California. He subsequently moved to the nearby Department of Nutritional Sciences at the University of California at Berkeley in 1961, and he continued to study the nutritional requirements and axenic cultivation of Caenorhabditis species, particularly C. briggsae, until his death in 1965. Although permanent cultures were maintained on nutrient agar slants inoculated with E. coli, an axenic medium (having no organism present) with chemically undefined supplements was developed in 1954 (Dougherty et al. 1959). Subsequently either monoxenic or axenic cultures of C. elegans and C. briggsae were provided to numerous investigators for research on nutrition, reproduction, genetics, and aging. Much of this early work on the biochemistry, physiology, culture, and nutrition of Caenorhabditis and other free-living nematodes can be found in Nicholas (1975) The Biology of Free-living Nematodes and in Zuckerman (1980) Nematodes as Biological Models, Volumes 1 and 2. Volume 1 includes chapters on C. elegans genetics, development, and behavior. More recently, anatomical and physiological information from C. elegans has been integrated with that from plant and animal parasitic species by Bird and Bird (1991) in the second edition of the classic monograph The Structure of Nematodes.

The Bergerac strain was found to exhibit a high spontaneous mutation frequency owing to transposition of the Tc1 transposon, which is present in high copy number (300—400 copies) in this strain (Moerman and Waterston 1984). It was crossed repeatedly with the low-copy-number (30 copies) Bristol strain to generate some of the “mutator” strains used for transposon tagging (Mori et al. 1988a). In part because the Bergerac males are essentially infertile and the hermaphrodites are temperature-sensitive sterile mutants (Fatt and Dougherty 1963), virtually all C. elegans genetics has been done with the Bristol strain, i.e., the N2 line that Sydney Brenner derived from the Bristol culture he obtained from Ellsworth Dougherty in the spring of 1964. However, some genetic work on the Bergerac strain was carried out in the laboratory of Jean-Louis Brun at Claude-Bernard University, Villeurbanne, France (Dion and Brun 1971; Abdul-Kader and Brun 1978). The Bergerac strain survives today as two diverged sublines, N62 (CB4851) and BO (RW7000). Several dumpy and lethal mutant lines derived from the Bergerac strain are also available.

Other wild-type strains of C. elegans have been isolated from numerous sites around the world (Fitch and Thomas, this volume). These strains sometimes display different traits (see, e.g., Barker 1994), but they are all interfertile with the N2 laboratory strain, which was defined in 1965 as the wild-type reference. C. briggsae seems to be much less common in nature. One isolate (G16) from Gujarat, India, has been reported and compared with the Dougherty strain of C. briggsae and with C. elegans N2 (Fodor et al. 1983). This analysis revealed that the C. briggsae strain, which descended from a single worm isolated in 1944 from soil on the Stanford University campus by Margaret Briggs Gochnauer (Gochnauer and McCoy 1954), had accumulated numerous mutations in its 40 years of laboratory cultivation. Consequently, the G16 isolate replaced the Briggs isolate as the wild-type reference, and currently available DNA libraries are derived from G16. Prior to Brenner (1974), C. briggsae had been the species of choice for most research, including a genetic study of a spontaneous “dwarf” mutant (Nigon and Dougherty 1950). It lost popularity in the 1970s because Brenner's work stimulated the adoption of C. elegans as a biological model (Edgar and Wood 1977), and because several Caenorhabditis laboratory lines thought to be C. briggsae were actually C. elegans (Friedman et al. 1977). C. briggsae had, in fact, been originally identified as C. elegans but was later reclassified and named as a new species (Dougherty and Nigon 1949).

Copyright © 1997, Cold Spring Harbor Laboratory Press.
Bookshelf ID: NBK20127


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