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In the next five years, molecular biology will get its first look at the complete genetic code of a multicellular animal. The Caenorhabditis elegans genome sequencing project, a collaboration between Robert Waterston's group in St. Louis and John Sulston's group in Cambridge, is currently on schedule towards its goal of obtaining the complete sequence of this organism and all its estimated 15,000 to 20,000 genes by 1998. By that time, we should also know the complete genome sequence of a few other organisms as well, including the prokaryote Escherichia coli and the single-celled eukaryote Saccharomyces
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Sorrentino V, Deplancke B, Ouhmad T, Cornaglia M, Gijs MA, Auwerx J, Williams EG, Krishnamani G, Frochaux MV, Nicolet-Dit-Felix AA, Lin T, Mouchiroud L
[
Curr Protoc Neurosci,
2016]
Phenotyping strategies in simple model organisms such as D. melanogaster and C. elegans are often broadly limited to growth, aging, and fitness. Recently, a number of physical setups and video tracking software suites have been developed to allow for accurate, quantitative, and high-throughput analysis of movement in flies and worms. However, many of these systems require precise experimental setups and/or fixed recording formats. We report here an update to the Parallel Worm Tracker software, which we termed the Movement Tracker. The Movement Tracker allows variable experimental setups to provide cross-platform automated processing of a variety of movement characteristics in both worms and flies and permits the use of simple physical setups that can be readily implemented in any laboratory. This software allows high-throughput processing capabilities and high levels of flexibility in video analysis, providing quantitative movement data on C. elegans and D. melanogaster in a variety of different conditions. 2016 by John Wiley and Sons, Inc.
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[
1960]
For the purpose of the present chapter the noun 'cultivation' is to be taken as the maintenance, in the laboratory, of a population of organisms belonging to a desired species through successive generations and subcultures over a prolonged period of time (weeks, months, or years). This is a deliberate restriction of the term. The noun 'culture' is most aptly used for a population within a circumscribed vessel or container (test-tube, Petri dish, U.S. Bureau of Plant Industry watch glass, etc.); it is also used in a looser, more general way (as "in culture") to cover conditions of substantial growth whether or not leading to cultivation in the strict sense
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[
Methods Cell Biol,
1995]
Geneticists like to point out that the ultimate test of a proposed function for a gene and its encoded product (or products) in a living organism involves making a mutant and analyzing its phenotype. This is the goal of reverse genetics: a gene is cloned and sequenced, its transcripts and protein coding sequence are analyzed, and a function may be proposed; one must then introduce a mutation in the gene in a living organism to see what the functional consequences are. The analysis of genetic mosaics takes this philosophy a step further. In mosaics, some cells of an individual are genotypically mutant and other cells are genotypically wild type. One then asks what the phenotypic consequences are for the living organism. This is not the same as asking what cells transcribe the gene or in what cells the protein product of the gene is to be found, but rather it is asking in what cells the wild-type gene is needed for a given function...
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[
1990]
Induction of the C. elegans vulva is a simple example of pattern formation in which the combined action of two intercellular signals specifies three cell types in a precise spatial pattern. These two signals, a graded inductive signal and a short-range lateral signal, are each mediated by a distinct genetic pathway. To understand how these intercellular signals specify cell type, we are studying, by genetic analysis and molecular cloning, genes whose products are involved in the induction pathway.
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[
Methods Cell Biol,
1995]
Although Caenorhabditis elegans was originally chosen as a model organism for cell biology with serial section electron microscopy (EM) methods in mind, these methods have remained a daunting challenge. There is an apocryphal story that Nichol Thomson originally advised Sydney Brenner that C. elegans was unsuitable for electron microscopy and that Brenner should choose another species. Other experienced microscopists have probably shared similar dark thoughts from time to time. Nonetheless, the worm's very small size, simple organization, and cablelike nervous system have permitted Brenner's colleagues to characterize every cell and cell contact in the wild-type animal, potentiating the genetic characterization of cellular development in remarkable detail. We attempt to provide an adequate background for anyone to initiate EM studies of C. elegans. Two decades ago, as the first of Brenner's postdoctoral fellows left his laboratory to establish new worm laboratories, it was standard practice to include an EM component in their studies. Their combined efforts to characterize the adult animal's cell types and the essential steps in its development helped to erect a lovely scaffold of key manuscripts, capped by the description of the "Mind of the Worm" in some 600 micrographs and 175 drawings. Many of these works required technical heroics or suffered long delays before publication. Most people later chose to leave electron microscopy behind in pursuit of molecular quarry. The fruits of their molecular and genetic studies should soon stimulate a renewed flowering of electron microscopy. We hope to smooth your entry or reentry into these techniques. We also summarize our methods for three-dimensional (3D) image reconstruction, based largely on film techniques introduced by John White and Randle Ware. Digital imaging techniques seem poised to make 3D reconstruction more accessible, and may simplify the exchange of morphological data between laboratories. We discuss several computer systems that the C. elegans community could adopt for high-resolution studies of structure and function. In addition, we briefly cover several specialized specimen preparation techniques for electron microscopy, including freeze fracture and electron microscopic immunocytochemistry.
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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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[
Methods Cell Biol,
1995]
The number of easily distinguishable mutant phenotypes in Caenorhabditis elegans is relatively small, and this constrains the number of factors that can be followed in standard genetic crosses. Consequently, a new mutation is mapped, first to a chromosome using two-factor data from one or more crosses, and then to a chromosomal subregion by successive three-factor crosses. Mapping would be more efficient if it were possible to score a large number of well-distributed markers in a single cross. The advent of the polymerase chain reaction makes this approach feasible by allowing polymorphic genomic regions to serve as genetic markers that are easily scored in DNA released from individual animals. The only "phenotype" is a band on a gel, so the segregation of many of these markers can be followed in a single cross. Following the terminology proposed by Olsen et al. (1989), we refer to polymorphisms that can be scored by appropriately designed polymerase chain reaction (PCR) assays as polymorphic seqeunce-tagged sites (STSs)...
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[
1985]
At first sight the inclusion of a chapter on Caenorhabditis elegans in a volume on cell biology may seem unusual. However this nematode has been a superb model system for a number of cell biology studies as well as a useful model of aging. This widespread interest in C. elegans is engendered in large part by its genetic system and its optical clarity in Nomarski phase-contrast optics. Nematodes have long been a system in wide use among experimental gerontologists, and with the introduction of C. elegans by Brenner in 1974, this species has become the nematode of choice for most aging studies. We concentrate primarily on C. elegans in this review although a number of other speices, including Caenorhabditis briggsae, Turbatrix aceti, and Panagrellus redivivus, have been used in aging studies also. Other reviews on aging in C. elegans have appeared recently, including a more detailed review in another volume of this series.
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[
Lecture Notes in Computer Science,
2008]
One of the most tractable organisms for the study of nervous systems is the nematode Caenorhabditis elegans, whose locomotion in particular has been the subject of a number of models. In this paper we present a first integrated neuro-mechanical model of forward locomotion. We find that a previous neural model is robust to the addition of a body with mechanical properties, and that the integrated model produces oscillations with a more realistic frequency and waveform than the neural model alone. We conclude that the body and environment are likely to be important components of the worms locomotion subsystem.