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[
WormBook,
2005]
A wide variety of bacterial pathogens, as well as several fungi, kill C. elegans or produce non-lethal disease symptoms. This allows the nematode to be used as a simple, tractable model host for infectious disease. Human pathogens that affect C. elegans include Gram-negative bacteria of genera Burkholderia, Pseudomonas, Salmonella, Serratia and Yersinia; Gram-positive bacteria Enterococcus, Staphylococcus and Streptococcus; and the fungus Cryptococcus neoformans. Microbes that are not pathogenic to mammals, such as the insect pathogen Bacillus thuringiensis and the nematode-specific Microbacterium nematophilum, are also studied with C. elegans. Many of the pathogens investigated colonize the C. elegans intestine, and pathology is usually quantified as decreased lifespan of the nematode. A few microbes adhere to the nematode cuticle, while others produce toxins that kill C. elegans without a requirement for whole, live pathogen cells to contact the worm. The rapid growth and short generation time of C. elegans permit extensive screens for mutant pathogens with diminished killing, and some of the factors identified in these screens have been shown to play roles in mammalian infections. Genetic screens for toxin-resistant C. elegans mutants have identified host pathways exploited by bacterial toxins.
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[
Modern Cell Biology,
1994]
During the development of any multicellular organism, the behavior of any given cell can be influenced in two ways: by its ancestry, i.e., by the particular pattern of determinants it inherits (lineal programming); or by its environment, i.e., the signals it receives from other cells. In C. elegans, the relative importance of these two factors for the development of any given cell can be examined with an unusually high degree of precision. There are a number of reasons for this, but perhaps the most important is that the cell lineage, the particular pattern of cell divisions and differentiations that occur in development, is known, and is largely the same from animal to animal. Alterations in the lineage, therefore, can be understood in terms of altered developmental decisions of
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[
Methods Cell Biol,
1995]
Compared with other animals, the nematode Caenorhabditis elegans has many advantages for mutant isolation and for genetic analysis. Some of these, for example, small size and rapid growth to high density on inexpensive media, simplify the manipulation of large numbers of animals. Others, such as the lack of a muscle-driven circulatory system and the self-fertilizing hermaphroditic mode of reproduction, enable the survival of strains with genetic defects that would be lethal to more complex animals. Although a few compounds with C. elegans-specific or nematode-specific actions have been described, the vast majority appear to act on targets that are widely distributed in most or all animals, including humans (or even in most or all eukaryotes). As a result, C. elegans has been a popular organism in which to study drug action and there is a substantial body of published work. In this chapter we attempt to extract an underlying feature of this work: the methods that are used in compound-based studies of C. elegans. We present general approaches to evaluating the effects of compounds on C. elegans growth, development, metabolism, and behavior, we discuss strategies for the isolation and analysis of drug-resistant and hypersensitive mutants, and we describe the use of C. elegans for new drug discovery. We also provide, as Table I, a list of some of the compounds already studied in C. elegans, along with one or more references in which information about the detection of compound-specific effects can be found. It is hoped the table will expedite the use of compound-specific mutants as genetic markers...
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[
WormBook,
2005]
Cell-cell interactions mediated by the Notch signaling pathway occur throughout C. elegans embryogenesis. These interactions have major roles in specifying cell fates and in tissue morphogenesis. The network of Notch interactions is linked in part through the Notch-regulated expression of components of the pathway, allowing one interaction to pattern subsequent ones. The Notch signal transduction pathway is highly conserved in animal embryogenesis. The REF-1 family of bHLH transcription factors are major targets of Notch signaling in the C. elegans embryo, and are distantly related to HES proteins that are targets of Notch signaling in Drosophila and vertebrates.
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[
WormBook,
2005]
A genetic enhancer is a mutation in one gene that intensifies the phenotype caused by a mutation in another gene. The phenotype of the double mutant is much stronger than the summation of the single mutant phenotypes. The isolation of enhancers can lead to the identification of interacting genes, including genes that act redundantly with respect to each other. Examples in Caenorhabditis elegans of dominant enhancers are presented first, followed by a review of recessive enhancers of null mutations. In some of these cases, the interacting genes are related in structure and function, but in other cases, the interacting genes are nonhomologous. Recessive enhancers of non-null mutations can also be useful. A powerful advance for the identification of recessive enhancers is genome-wide screening based on RNA interference.
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[
1993]
We now know that the invariance of C. elegans development arises in part from highly reproducible cell interactions. Each cell is formed in an identical position within the developing organism and is therefore susceptible to the same set of intercellular signals. Some of these interactions involve signals among cells of equivalent developmental potential (lateral signalling) while other involve signals between cells of distinct developmental potential (induction). The invariant development and the small cell number of this nematode species allows study of cell interactions at the level of individual cells. Recent molecular evidence indicates that nematodes share many classes of proteins with vertebrates and insects, including proteins involved in signal transduction and transcriptional regulation. Thus, from the point of view of developmental phenomenology and molecular mechanisms, nematodes provide a useful experimental system for the study of general properties of cell signalling.
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Applications of, and investigations on lectins in nematology reflect the existing classification of nematodes according to their life-styles, i.e. free-living, plant-parasitic and animal-parasitic. In animal-parasitic nematodes, lectins have predominately been used to study the cuticle and its interaction between nematode and host. In plant-parasitic nematodes, investigations on the cuticle and amphid exudates have been predominant. Nematode-plant interactions on the other hand have attracted only minor attention. Ironically, however, the free-living nematodes in general, and the widely used model system Caenorhabditis elegans in particular, have been used very little for study of lectins, in spite of the many advantages offered by this organism as a genetic and an experimental model system.
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[
Methods Cell Biol,
1995]
One way to study cell function is to eliminate the cell and observe subsequent developmental or behavioral abnormalities in the animal. In Caenorhabditis elegans, this is usually accomplished by killing individual cells or groups of cells with a laser microbeam. Laser killing has been used to determine the functions of many mature cell types, including neurons involved in locomotion, feeding, mechanosensation, and chemosensation. These studies have been practical because only a few cell types appear to be absolutely required for viability. Laser ablation can also be sued to ask how cells interact during development. Signaling and inductive interactions between cells can be examined by removing one cell and observing the development of the remaining cells...
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[
Methods Mol Biol,
2011]
PhospoPep version 2.0 is a project to support systems biology signaling research by providing interactive interrogation of MS-derived phosphorylation data from four different organisms. Currently the database hosts phosphorylation data from the fly (Drosophila melanogaster), human (Homo sapiens), worm (Caenorhabditis elegans), and yeast (Saccharomyces cerevisiae). The following will give an overview of the content and usage of the PhosphoPep database.
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[
1984]
Current knowledge concerning the protein components of muscle is based largely on biochemical analysis of myofibrillar preparations. Such in vitro studies are limited because direct evidence for the in vivo function of isolated proteins is difficult to obtain. In vitro techniques, futhermore, are restricted often to the study of abundant proteins. Very little is known about minor sarcomeric components or how the sarcomere is assembled overall. Certainly, the assembly and function of a structure as complex as the sarcomere require many more than the dozen or so proteins commonly studied. Genetic techniques provide an alternative approach to the study of muscle. Mutations that cause muscle disfunction define genes required to construct a normal muscle. cell. The nature of mutant defects provides insights into the functions of the wild-type gene products. Genetic analysis is not restricted to the study of abundant proteins. The genes for even low-abundance proteins are subject to mutation, and if a gene product is required for muscle assembly or function, such mutants will be muscle-defective. Macromolecular complexes provide special opportunities for genetic intervention, because gene products that directly interact in the structure can often be identified. Mutational defects that affect one member of an interacting pair of proteins can be compensated by mutations affecting its interacting partner. Not all genes, hwoever, are directly accessible to genetic analysis. For example, genes whose products are essential for cell or organism viability and genes having more than one functional copy present special problems.....