Search Results for: "Caenorhabditis elegans"

Author: Timmons, Lisa; Tabara, Hiroaki; Mello, Craig C.; Fire, Andrew Z. Description: Introduction of double-stranded RNA (dsRNA) can elicit a gene-specific RNA interference response in a variety of organisms and cell types. In many cases, this response has a systemic character in that silencing of gene expression is observed in cells distal from the site of dsRNA delivery. The molecular mechanisms underlying the mobile nature of RNA silencing are unknown. For example, although cellular entry of dsRNA is possible, cellular exit of dsRNA from normal animal cells has not been…

Author: Treinin, M.; Shliar, J.; Jiang, H.; Powell-Coffman, J.A.; Bromberg, Z.; Horowitz, M. Description: Chronic exposure to environmental heat improves tolerance via heat acclimation (AC). Our previous data on mammals indicate that reprogramming the expression of genes coding for stress proteins and energy-metabolism enzymes plays a major role. Knowledge of pathways leading to AC is limited. For their identification, we established a Caenorhabditis elegans AC model and tested mutants in which signaling pathways pertinent to acclimatory responses are mutated. AC attained by maintaining adult C. elegans at 25 degrees C…

Author: Croll, N.A. Description: The behavioural activities during movement, feeding and defaecation have been recorded and measured in adult females of Caenorhabditis elegans. The postures and components of recognizable wave forms are described. Stress has been laid on the mechanism of antagonistic interaction of backward and forward movement, and the rates and characteristics of “spontaneous” and “induced” reversal periods. During feeding, rapid rates of pharyngeal activity are invariably related to low rates of somatic muscle wave propagation. Head oscillations are considered to be separate events not directly linked with feeding…

Author: Sterken, M.G.; Snoek, L.B.; Kammenga, J.E.; Andersen, E.C. Description: Model organisms are of great importance to our understanding of basic biology and to making advances in biomedical research. However, the influence of laboratory cultivation on these organisms is underappreciated, and especially how that environment can affect research outcomes. Recent experiments led to insights into how the widely used laboratory reference strain of the nematode Caenorhabditis elegans compares with natural strains. Here we describe potential selective pressures that led to the fixation of laboratory-derived alleles for the genes npr-1, glb-5,…

Author: White, J. G.; Southgate, E.; Thomson, J. N.; Brenner, S. Description: The structure and connectivity of the nervous system of the nematode Caenorhabditis elegans has been deduced from reconstructions of electron micrographs of serial sections. The hermaphrodite nervous system has a total complement of 302 neurons, which are arranged in an essentially invariant structure. Neurons with similar morphologies and connectivities have been grouped together into classes; there are 118 such classes. Neurons have simple morphologies with few, if any, branches. Processes from neurons run in defined positions within bundles…

Author: Klass, M. R. Description: At each molt a normal animal passes through “lethargus,” a stage in which feeding and locomotion are transiently arrested. In the dauerlarva stage, feeding is arrested indefinitely, and locomotion is markedly reduced. A simple quantitative assay, based on the exceptional resistance of dauerlarvae to sodium dodecyl sulfate (SDS), has been developed to study dauerlarva formation and its reversal. The SDS resistance of dauerlarvae requires both non-feeding and an especially impermeable cuticle. Dauerlarva formation can be efficiently induced by limiting the concentration of bacteria (the food…

Author: Cassada, R. C.; Russell, R. L. Description: In the postembryological development of the free-living nematode Caenorhabditis elegans, a morphologically recognizable, nongrowing stage, called the dauerlarva, may arise. Using synchronous populations and following growth and molting, it has been shown that the dauerlarva is formed by a facultative, reversible arrest at a specific point in the life cycle, the second of four cuticle molts, in response to external conditions. Subject headings: Animals; Environment; Feeding Behavior; Glucose; Larva; Mutation; Nematoda; Sodium Chloride; Sodium Dodecyl Sulfate; Temperature; Caenorhabditis elegans; C elegans; Dauerlarva Publication…