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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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[
2017]
Since their discovery in late 1970, transient receptor potential (TRP) channels have been implicated in a variety of cellular and physiological functions (Minke, 2010). The superfamily of TRP channels consists of nearly 30 members that are organized into seven major subgroups based on their specific function and sequence similarities (Owsianik et al., 2006; Ramsey et al., 2006). With the exception of TRPN channels that are only found in invertebrates and fish, mammalian genomes contain representatives of all six subfamilies: (1) TRPV (vanilloid); (2) TRPC (canonical); (3) TRPM (melastatin); (4) TRPA (ankyrin); (5) TRPML (mucolipin); and (6) TRPP (polycystin). TRP channels play crucial regulatory roles in many physiological processes, including those associated with reproductive tissues. As calcium-permeable cation channels that respond to a variety of signals (Clapham et al., 2003; Wu et al., 2010), TRP channels exert their role as sensory detectors in both male and female gametes, and play regulatory functions in germ cell development and maturation. Recent evidence obtained from Caenorhabditis elegans studies point to the importance of these proteins during fertilization where certain sperm TRP channels could migrate from a spermatozoon into an egg to ensure successful fertilization and embryo development. In this chapter we discuss how TRP channels can regulate both female and male fertility in different species and their specific roles.
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[
1994]
Nematodes have been cultured continuously in the laboratory since 1944 when Margaret Briggs Gochnauer isolated and cultured the free-living hermaphroditic species Caenorhabditis briggsae. Work with C. briggsae and other rhabditid nematodes, C. elegans, Rhabditis anomala, and R. pellio, demonstrated the relative ease with which they could be cultured. The culturing techniques described here were developed for C. elegans, but are generally suitable (to varying degrees) for other free-living nematodes. Whereas much of the early work involved axenic culturing, most of these techniques are no longer in common use and are not included here. In the 1970s C. elegans became the predominant research model due to work by Brenner and co-workers on the genetics and development of this species. An adult C. elegans is about 1.5 mm long, and under optimal laboratory conditions has a life cycle of approximately 3 days. There are two sexes, males and self-fertile hermaphrodites, that are readily distinguishable as adults. The animals are transparent throughout the life cycle, permitting observation of cell divisions in living animals using differential interference microscopy. The complete cell lineage and neural circuitry have been determined and a large collection of behavioral and anatomical mutants have been isolated. C. elegans has six developmental stages: egg, four larval stages (L1-L4), and adult. Under starvation conditions or specific manipulations of the culture conditions a developmentally arrested dispersal stage, the dauer larva, can be formed as an alternative third larval stage. Many of the protocols included here and other experimental protocols have been summarized in "The Nematode Caenorhabditis elegans". We also include a previously unpublished method for long-term chemostat cultures of C. elegans. General laboratory culture conditions for nematode parasites of animals have been described, but none of these nematodes can be cultured in the laboratory through more than one life cycle. Marine nematodes and some plant parasites have been cultured xenically or with fungi. Laboratory cultivation of several plant parasites on Arabidopsis thaliana seedlings in agar petri plates has also been reported.
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[
1983]
The advantages of the free-living nematode Caenrohabditis elegans as a model for pharmacologic, toxicant and anthelmintic testing have become apparent to many companies, and the application of this organism as a primary screen for test compounds or toxic agents has expanded rapidly. It is appropriate to briefly summarize some of this nematode's qualities, to invoke an appreciation of this elegant system. As true of many invertebrate test organisms, C. elegans is small (about 1 mm X 40 u at maturity) and has a short life cycle: reproduction starts on day 3-4, ceases by day 14 and by day 25 it dies. Thus, for aging studies, all the symptoms of senescence are compressed into a short time period. In addition, this nematode has a small, fixed number of cells (about 830 at maturity) and differentiated organ systems: nervous, excretory, muscular, digestive and reproductive. The preceding characteristics are not unique in invertebrate model systems and their enumeration fails to explain the increasing popularity of C. elegans as a test organism. To understand this phenomenon several additional facts must be emphasized. First, the selection of C. elegans for detailed studies on the genetic control and regulation of behavior and developmental processes has fostered a wealth of knowledge on its neuroanatomy, cell lineages, biochemistry and behavior. There is now undoubtedly more accumulated knowledge on C. elegans than on any other multicellular creature. It is also the largest metazoan which can be continuously cultured on a chemically defined medium, and though most studies have proceeded on undefined media or in monoxenic culture (utilizing a bacterium as a food source), this property can be exploited for precise nutritional studies. In regard to aging studies, the question of relevance of aging in the nematode to that in mammals has been answered in respect to some parameters which characterize senescence in humans, and further study will define other features of aging which are common to all metazoa. In practical terms, this means that test which require 24-36 months to rear an aged rat for evaluation of a pharmaceutical, can potentially be accomplished in 21 days using the nematode. The paper emphasizes that the use of the C. elegans system as a primary screen for candidate compounds to intervene in the aging process can save time, effort and money, while