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Caenorhabditis elegans is a free-living soil nematode, about 1 mm in length, that is found around the world. It is currently a common laboratory model for many aspects of cellular, developmental, and molecular biology. Its popularity comes from its transparency (allowing all nuclei to be followed in living animals at all stages of development), its anatomical simplicity (1000 cells), its small genome (100 Mbp), an invariant somatic cell lineage, ease of laboratory culture, rapid generation time, and a mode of reproduction which facilitates classical genetic analysis. An interested beginner needs only a petri plate, some Escherichia coli, and a stereo dissecting microscope to begin study of this fascinating creature.
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[
1987]
Each year thousands of new chemicals are developed but the potential societal benefits are often unrealized or delayed due to the lack of toxicological data. In the past, chemicals were introduced into the environment with little or no toxicological testing. This has resulted in many examples where adverse effects to humans were seen only after years of exposure (e.g., asbestos, benzene, vinyl chloride). Because few chemicals are used as pure substances, the toxicity of mixtures is another problem. However, these potential chemical interactions are seldom evaluated. All of the above have increased the need for toxicological testing.
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[
2000]
Computer tracking of Caenorhabditis elegans, a free-living soil nematode, is a promising tool to assess behavioral changes upon exposure to contaminants. A short life cycle, a known genetic make-up, thoroughly studied behavior, and a completely mapped nervous system make C. elegans an attractive soil test organism with many advantages over the commonly used earthworm. Although many toxicity tests have been performed with C. elegans, the majority focused on mortality, a much less sensitive endpoint than behavior. A computer tracking system has been developed to monitor behavioral changes using C. elegans. Because conditions unrelated to specific toxicant exposures, such as changes in temperature, developmental stage, and presence of adequate food sources, can affect behavior, there is a need to standardize tracking procedures. To this end, we have developed reference charts for control movement comparing the movement of four and five day-old adult nematodes. The use of K-medium versus deionized (DI) H2O for pre-tracking rinses was also investigated. A final reference chart compared the behavioral responses of nematodes at various food densities (i.e. bacterial concentrations).
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[
1987]
One way to gain an understanding of any biological process is through the use of mutant analysis and selective breeding to generate stocks which have genetic alterations in that process. We have taken just this approach in the analysis of aging...
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[
1990]
Caenorhabditis elegans is a short-lived species that has been widely used in the genetic dissection of development. This species is becoming important in the genetic analysis of aging because strains with mean life spans more than 70% longer than wild type have been identified both through the use of recombinant inbred lines and by the induction of single-gene mutants. Its unique hermaphroditic mode of reproduction leads to a lack of inbreeding depression and simplifies genetic analyses of quantitative traits such as length of life or behavior. Aging in this organism is composed of at least three independent processes: that specifying length of life, that specifying reproductive senescence, and that specifying senescence of the general motor system. These data suggest that aging is not a unitary process but that many different processes or independent components may be involved in various aspects of aging. Most importantly, an apparent single-gene mutation has been mapped to the middle of linkage group II; this mutation lengthens mean and maximum life span 60-110% and also decreases fertility about five-fold.