Caenorhabditis elegans is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek caeno- (recent), rhabditis (rod-like) and Latin elegans (elegant). In 1900, Maupas initially named it Rhabditides elegans. Osche placed it in the subgenus Caenorhabditis in 1952, and in 1955, Dougherty raised Caenorhabditis to the status of genus.
Biological databases are libraries of biological sciences, collected from scientific experiments, published literature, high-throughput experiment technology, and computational analysis. They contain information from research areas including genomics, proteomics, metabolomics, microarray gene expression, and phylogenetics. Information contained in biological databases includes gene function, structure, localization, clinical effects of mutations as well as similarities of biological sequences and structures.
Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding, or breeding of related individuals. Population biological fitness refers to an organism's ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression.
A sheep–goat hybrid is the offspring of a sheep and a goat. While sheep and goats seem similar and can be mated, they belong to different genera in the subfamily Caprinae of the family Bovidae. Sheep belong to the genus Ovis and have 54 chromosomes, while goats belong to the genus Capra and have 60 chromosomes. The offspring of a sheep-goat pairing is generally stillborn. Despite widespread shared pasturing of goats and sheep, hybrids are very rare, indicating the genetic distance between the two species. They are not to be confused with sheep–goat chimera, which are artificially created by combining the embryos of a goat and a sheep.
Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between two species and their parents was thought to be particularly difficult to achieve, and thus hybrid species were thought to be very rare. With DNA analysis becoming more accessible in the 1990s, hybrid speciation has been shown to be a somewhat common phenomenon, particularly in plants. In botanical nomenclature, a hybrid species is also called a nothospecies. Hybrid species are by their nature polyphyletic.
Caenorhabditis briggsae is a small nematode, closely related to Caenorhabditis elegans. The differences between the two species are subtle. The male tail in C. briggsae has a slightly different morphology from C. elegans. Other differences include changes in vulval precursor competence and the placement of the excretory duct opening. C. briggsae is frequently used to study the differences between it and the more intimately understood C. elegans, especially at the DNA and protein sequence level. Several mutant strains of C. briggsae have also been isolated that facilitate genetic analysis of this organism. C. briggsae, like C. elegans, is a hermaphrodite. The genome sequence for C. briggsae was determined in 2003.
Caenorhabditis is a genus of nematodes which live in bacteria-rich environments like compost piles, decaying dead animals and rotting fruit. The name comes from Greek: caeno- ; rhabditis = rod-like. In 1900, Maupas initially named the species Rhabditis elegans, Osche placed it in the subgenus Caenorhabditis in 1952, and in 1955, Dougherty raised Caenorhabditis to the status of genus.
Barbara J. Meyer is a biologist and genetist, noted for her pioneering research on lambda phage, a virus that infects bacteria; discovery of the master control gene involved in sex determination; and studies of gene regulation, particularly dosage compensation. Meyer’s work has revealed mechanisms of sex determination and dosage compensation -- that balance X-chromosome gene expression between the sexes in Caenorhabditis elegans that continue to serve as the foundation of diverse areas of study on chromosome structure and function today.
SmY ribonucleic acids are a family of small nuclear RNAs found in some species of nematode worms. They are thought to be involved in mRNA trans-splicing.
The nematode worm Caenorhabditis elegans was first studied in the laboratory by Victor Nigon and Ellsworth Dougherty in the 1940s, but came to prominence after being adopted by Sydney Brenner in 1963 as a model organism for the study of developmental biology using genetics. In 1974, Brenner published the results of his first genetic screen, which isolated hundreds of mutants with morphological and functional phenotypes, such as being uncoordinated. In the 1980s, John Sulston and co-workers identified the lineage of all 959 cells in the adult hermaphrodite, the first genes were cloned, and the physical map began to be constructed. In 1998, the worm became the first multi-cellular organism to have its genome sequenced. Notable research using C. elegans includes the discoveries of caspases, RNA interference, and microRNAs. Six scientists have won the Nobel prize for their work on C. elegans.
Jonathan Alan Hodgkin is a British biochemist, Professor of Genetics at the University of Oxford, and an emeritus fellow of Keble College, Oxford.
WormBase is an online biological database about the biology and genome of the nematode model organism Caenorhabditis elegans and contains information about other related nematodes. WormBase is used by the C. elegans research community both as an information resource and as a place to publish and distribute their results. The database is regularly updated with new versions being released every two months. WormBase is one of the organizations participating in the Generic Model Organism Database (GMOD) project.
Caenorhabditis angaria is a small nematode, in the same genus as the model organism Caenorhabditis elegans. The name is from the Latin after the tendency to ride weevils. Prior to 2011, the species was referred to as C. sp. 2, C. sp. 3, and C. sp. PS1010. Its genome was sequenced at the California Institute of Technology in 2010. This species is gonochoristic. It has distinct morphology and behavior compared to C. elegans; notably, C. angaria males exhibit a spiral mating behavior. Its divergence from C. elegans is similar to the distance between humans and fish. C. castelli is its closest relative, and the two species can produce F1 hybrids.
Caenorhabditis tropicalis - prior to 2014 referred to as C. sp. 11, is a species of Caenorhabditis nematodes.
Caenorhabditis doughertyi is a species of nematodes in the genus Caenorhabditis. Prior to 2014, it was referred to as C. sp. 10
Victor Marc Nigon was a biologist who was first to study the nematode worm Caenorhabditis elegans in the laboratory, with Ellsworth Dougherty, in the 1940s.
Caenorhabditis sinica, prior to 2014 described as sp. 5, is a species of nematodes in the genus Caenorhabditis. It is found in East Asia. It is found frequently in China.
Holocentric chromosomes are chromosomes that possess multiple kinetochores along their length rather than the single centromere typical of other chromosomes. They have been described for the first time in cytogenetic experiments dating from 1935 and, since this first observation, the term holocentric chromosome has referred to chromosomes that: i) they lack the primary constriction corresponding to centromere observed in monocentric chromosomes; and ii) they possess multiple kinetochores dispersed along the chromosomal axis so that microtubules bind to chromosomes along their entire length and move broadside to the pole from the metaphase plate. These chromosomes are also termed holokinetic, because, during cell division, chromatids move apart in parallel and do not form the classical V-shaped figures typical of monocentric chromosomes. Holocentric chromosomes evolved several times during both animal and plant evolution and are currently reported in about eight hundred diverse species, including plants, insects, arachnids and nematodes As a consequence of their diffuse kinetochores, holocentric chromosomes may stabilize chromosomal fragments favouring karyotype rearrangements. However, holocentric chromosome may also present limitations to crossing over causing a restriction of the number of chiasma in bivalents and may cause a restructuring of meiotic divisions resulting in an inverted meiosis.
Eukaryote hybrid genomes result from interspecific hybridization, where closely related species mate and produce offspring with admixed genomes. The advent of large-scale genomic sequencing has shown that hybridization is common, and that it may represent an important source of novel variation. Although most interspecific hybrids are sterile or less fit than their parents, some may survive and reproduce, enabling the transfer of adaptive variants across the species boundary, and even result in the formation of novel evolutionary lineages. There are two main variants of hybrid species genomes: allopolyploid, which have one full chromosome set from each parent species, and homoploid, which are a mosaic of the parent species genomes with no increase in chromosome number.
Paul W. Sternberg is an American biologist. He does research for WormBase on C. elegans, a model organism.
