Caenorhabditis elegans (/ˌsiːnoʊræbˈdaɪtəs ˈɛləɡænz/) 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.
C. elegans is an unsegmented pseudocoelomate and lacks respiratory or circulatory systems. Most of these nematodes are hermaphrodites and a few are males. Males have specialised tails for mating that include spicules.
In 1963, Sydney Brenner proposed research into C. elegans primarily in the area of neuronal development. In 1974, he began research into the molecular and developmental biology of C. elegans, which has since been extensively used as a model organism. It was the first multicellular organism to have its whole genome sequenced, and as of 2012, is the only organism to have its connectome (neuronal "wiring diagram") completed.
|An adult hermaphrodite C. elegans worm|
C. elegans is unsegmented, vermiform, and bilaterally symmetrical. It has a cuticle (a tough outer covering, as an exoskeleton), four main epidermal cords, and a fluid-filled pseudocoelom (body cavity). It also has some of the same organ systems as larger animals. About one in a thousand individuals is male and the rest are hermaphrodites. The basic anatomy of C. elegans includes a mouth, pharynx, intestine, gonad, and collagenous cuticle. Like all nematodes, they have neither a circulatory nor a respiratory system. The four bands of muscles that run the length of the body are connected to a neural system that allows the muscles to move the animal's body only as dorsal bending or ventral bending, but not left or right, except for the head, where the four muscle quadrants are wired independently from one another. When a wave of dorsal/ventral muscle contractions proceeds from the back to the front of the animal, the animal is propelled backwards. When a wave of contractions is initiated at the front and proceeds posteriorly along the body, the animal is propelled forwards. Because of this dorsal/ventral bias in body bends, any normal living, moving individual tends to lie on either its left side or its right side when observed crossing a horizontal surface. A set of ridges on the lateral sides of the body cuticle, the alae, is believed to give the animal added traction during these bending motions.
In relation to lipid metabolism, C. elegans does not have any specialized adipose tissues, a pancreas, a liver, or even blood to deliver nutrients compared to mammals. Neutral lipids are instead stored in the intestine, epidermis, and embryos. The epidermis corresponds to the mammalian adipocytes by being the main triglyceride depot. 
The pharynx is a muscular food pump in the head of C. elegans, which is triangular in cross-section. This grinds food and transports it directly to the intestine. A set of "valve cells" connects the pharynx to the intestine, but how this valve operates is not understood. After digestion, the contents of the intestine are released via the rectum, as is the case with all other nematodes. No direct connection exists between the pharynx and the excretory canal, which functions in the release of liquid urine.
Numerous gut granules are present in the intestine of C. elegans, the functions of which are still not fully known, as are many other aspects of this nematode, despite the many years that it has been studied. These gut granules are found in all of the Rhabditida orders. They are very similar to lysosomes in that they feature an acidic interior and the capacity for endocytosis, but they are considerably larger, reinforcing the view of their being storage organelles. A remarkable feature of the granules is that when they are observed under ultraviolet light, they react by emitting an intense blue fluorescence. Another phenomenon seen is termed 'death fluorescence'. As the worms die, a dramatic burst of blue fluorescence is emitted. This death fluorescence typically takes place in an anterior to posterior wave that moves along the intestine, and is seen in both young and old worms, whether subjected to lethal injury or peacefully dying of old age. Many theories have been posited on the functions of the gut granules, with earlier ones being eliminated by later findings. They are thought to store zinc as one of their functions. Recent chemical analysis has identified the blue fluorescent material they contain as a glycosylated form of anthranilic acid (AA). The need for the large amounts of AA the many gut granules contain is questioned. One possibility is that the AA is antibacterial and used in defense against invading pathogens. Another possibility is that the granules provide photoprotection; the bursts of AA fluorescence entail the conversion of damaging UV light to relatively harmless visible light. This is seen a possible link to the melanin–containing melanosomes.
The hermaphroditic worm is considered to be a specialized form of self-fertile female, as its soma is female. The hermaphroditic germline produces male gametes first, and lays eggs through its uterus after internal fertilization. Hermaphrodites produce all their sperm in the L4 stage (150 sperm cells per gonadal arm) and then produce only oocytes. The hermaphroditic gonad acts as an ovotestis with sperm cells being stored in the same area of the gonad as the oocytes until the first oocyte pushes the sperm into the spermatheca (a chamber wherein the oocytes become fertilized by the sperm).
The male can inseminate the hermaphrodite, which will preferentially use male sperm (both types of sperm are stored in the spermatheca).
The sperm of C. elegans is amoeboid, lacking flagella and acrosomes. When self-inseminated, the wild-type worm lays about 300 eggs. When inseminated by a male, the number of progeny can exceed 1,000. Hermaphrodites do not typically mate with other hermaphrodites. At 20°C, the laboratory strain of C. elegans (N2) has an average lifespan around 2–3 weeks and a generation time of 3 to 4 days.
C. elegans has five pairs of autosomes and one pair of sex chromosomes. Sex in C. elegans is based on an X0 sex-determination system. Hermaphrodites of C. elegans have a matched pair of sex chromosomes (XX); the rare males have only one sex chromosome (X0).
The fertilized zygote undergoes rotational holoblastic cleavage.
Sperm entry into the oocyte commences formation of an anterior-posterior axis. The sperm microtubule organizing center directs the movement of the sperm pronucleus to the future posterior pole of the embryo, while also inciting the movement of PAR proteins, a group of cytoplasmic determination factors, to their proper respective locations. As a result of the difference in PAR protein distribution, the first cell division is highly asymmetric. C. elegans embryogenesis is among the best understood examples of asymmetric cell division.
All cells of the germline arise from a single primordial germ cell, called the P4 cell, established early in embryogenesis. This primordial cell divides to generate two germline precursors that do not divide further until after hatching.
The resulting daughter cells of the first cell division are called the AB cell (containing PAR-6 and PAR-3) and the P1 cell (containing PAR-1 and PAR-2). A second cell division produces the ABp and ABa cells from the AB cell, and the EMS and P2 cells from the P1 cell. This division establishes the dorsal-ventral axis, with the ABp cell forming the dorsal side and the EMS cell marking the ventral side. Through Wnt signaling, the P2 cell instructs the EMS cell to divide along the anterior-posterior axis. Through Notch signaling, the P2 cell differentially specifies the ABp and ABa cells, which further defines the dorsal-ventral axis. The left-right axis also becomes apparent early in embryogenesis, although it is unclear exactly when specifically the axis is determined. However, most theories of the L-R axis development involve some kind of differences in cells derived from the AB cell.
Gastrulation occurs after the embryo reaches the 26-cell stage. C. elegans are a species of protostomes, so the blastopore eventually forms the mouth. Involution into the blastopore begins with movement of the endoderm cells and subsequent formation of the gut, followed by the P4 germline precursor, and finally the mesoderm cells, including the cells that eventually form the pharynx. Gastrulation ends when epiboly of the hypoblasts closes the blastopore.
Under environmental conditions favourable for reproduction, hatched larvae develop through four larval stages - L1,L2,L3, and L4 - in just 3 days at 20 °C. When conditions are stressed, as in food insufficiency, excessive population density or high temperature, C. elegans can enter an alternative third larval stage, L2d, called the dauer stage (Dauer is German for permanent). Dauer larvae are stress-resistant; they are thin and their mouths are sealed with a characteristic dauer cuticle and cannot take in food. They can remain in this stage for a few months. The stage ends when conditions improve favour further growth of the larva, now moulting into the L4 stage, even though the gonad development is arrested at the L2 stage .
Each stage transition is punctuated by a molt of the worm's transparent cuticle. Transitions through these stages is controlled by genes of the heterochronic pathway, an evolutionarily conserved set of regulatory factors. Many heterochronic genes code for microRNAs, which repress the expression of heterochronic transcription factors and other heterochronic miRNAs. miRNAs were originally discovered in C. elegans. Important developmental events controlled by heterochronic genes include the division and eventual syncitial fusion of the hypodermic seam cells, and their subsequent secretion of the alae in young adults. It is believed that the heterochronic pathway represents an evolutionarily conserved predecessor to circadian clocks.
Nematodes have a fixed, genetically determined number of cells, a phenomenon known as eutely. The adult hermaphrodite has 959 somatic cells, while the male C. elegans has 1031 cells. The number of cells does not change after cell division ceases at the end of the larval period, and subsequent growth is due solely to an increase in the size of individual cells.
The different Caenorhabditis species occupy various nutrient- and bacteria-rich environments. They feed on the bacteria that develop in decaying organic matter (microbivory). Soil lacks enough organic matter to support self-sustaining populations. C. elegans can survive on a diet of a variety of bacteria, but its wild ecology is largely unknown. Most laboratory strains were taken from artificial environments such as gardens and compost piles. More recently, C. elegans has been found to thrive in other kinds of organic matter, particularly rotting fruit.
C. elegans can also use different species of yeast, including Cryptococcus laurentii and Cryptococcus kuetzingii, as sole source of food. Although a bacterivore, C. elegans can be killed by a number of pathogenic bacteria, including human pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica or Enterococcus faecalis.
Invertebrates such as millipedes, insects, isopods, and gastropods can transport dauer larvae to various suitable locations. The larvae have also been seen to feed on their hosts when they die.
Nematodes can survive desiccation, and in C. elegans, the mechanism for this capability has been demonstrated to be late embryogenesis abundant proteins.
C. elegans, as other nematodes, can be eaten by predator nematodes and other omnivores, including some insects.
Arthrobotrys oligospora is the model organism for interactions between fungi and nematodes. It is the most common nematode capturing fungus, and most widespread nematode trapping fungus in nature.
In 1963, Sydney Brenner proposed using C. elegans as a model organism for the investigation primarily of neural development in animals. It is one of the simplest organisms with a nervous system. The neurons do not fire action potentials, and do not express any voltage-gated ion channels. In the hermaphrodite, this system comprises 302 neurons the pattern of which has been comprehensively mapped, in what is known as a connectome, and shown to be a small-world network. Research has explored the neural and molecular mechanisms that control several behaviors of C. elegans, including chemotaxis, thermotaxis, mechanotransduction, learning, memory, and mating behaviour, and recently has been used as a model organism for study molecular mechanisms in metabolic diseases. Brenner also chose it as it is easy to grow in bulk populations, and convenient for genetic analysis. It is a multicellular eukaryotic organism, yet is simple enough to be studied in great detail. The transparency of C. elegans facilitates the study of cellular differentiation and other developmental processes in the intact organism. The spicules in the male clearly distinguish males from females. Strains are cheap to breed and can be frozen. When subsequently thawed, they remain viable, allowing long-term storage. Maintenance is easy when compared to other multicellular model organisms, a few hundred nematodes can be kept on a single agar plate and suitable growth medium. Brenner described the use of a mutant of E. coli – OP50. OP50 is a uracil-requiring organism and its deficiency in the plate prevents the overgrowth of bacteria which would obscure the worms. The use of OP50 does not demand any major laboratory safety measures, since it is non-pathogenic and is easily grown in Luria-Bertani (LB) media overnight .
The developmental fate of every single somatic cell (959 in the adult hermaphrodite; 1031 in the adult male) has been mapped. These patterns of cell lineage are largely invariant between individuals, whereas in mammals, cell development is more dependent on cellular cues from the embryo.
As mentioned previously, the first cell divisions of early embryogenesis in C. elegans are among the best understood examples of asymmetric cell divisions, and the worm is a very popular model system for studying developmental biology.
Programmed cell death (apoptosis) eliminates many additional cells (131 in the hermaphrodite, most of which would otherwise become neurons); this "apoptotic predictability" has contributed to the elucidation of some apoptotic genes. Cell death-promoting genes and a single cell-death inhibitor have been identified.
RNA interference (RNAi) is a relatively straightforward method of disrupting the function of specific genes. Silencing the function of a gene can sometimes allow a researcher to infer its possible function(s). The nematode can be soaked in, injected with, or fed with genetically transformed bacteria that express the double-stranded RNA of interest, the sequence of which complements the sequence of the gene that the researcher wishes to disable. RNAi has emerged as a powerful tool in the study of functional genomics. In C. elegans, it has been used to analyse gene functions and the report claims the promise of future findings in the systematic genetic interactions.
Environmental RNAi uptake is much worse in other species of worms in the genus Caenorhabditis. Although injecting RNA into the body cavity of the animal induces gene silencing in most species, only C. elegans and a few other distantly related nematodes can take up RNA from the bacteria they eat for RNAi. This ability has been mapped down to a single gene, sid-2, which, when inserted as a transgene in other species, allows them to take up RNA for RNAi as C. elegans does.
Research into meiosis has been considerably simplified since every germ cell nucleus is at the same given position as it moves down the gonad, so is at the same stage in meiosis. In an early phase of meiosis, the oocytes become extremely resistant to radiation and this resistance depends on expression of genes rad51 and atm that have key roles in recombinational repair. Gene mre-11 also plays a crucial role in recombinational repair of DNA damage during meiosis. A study of the frequency of outcrossing in natural populations showed that selfing is the predominant mode of reproduction in C. elegans, but that infrequent outcrossing events occur at a rate around 1%. Meioses that result in selfing are unlikely to contribute significantly to beneficial genetic variability, but these meioses may provide the adaptive benefit of recombinational repair of DNA damages that arise, especially under stressful conditions.
Nicotine dependence can also be studied using C. elegans because it exhibits behavioral responses to nicotine that parallel those of mammals. These responses include acute response, tolerance, withdrawal, and sensitization.
As for most model organisms, scientists that work in the field curate a dedicated online database and the WormBase is that for C. elegans. The WormBase attempts to collate all published information on C. elegans and other related nematodes. Their website has advertised a reward of $4000 for the finder of a new species of closely related nematode. Such a discovery would broaden research opportunities with the worm.
C. elegans has been a model organism for research into ageing; for example, the inhibition of an insulin-like growth factor signaling pathway has been shown to increase adult lifespan threefold; while glucose feeding promotes oxidative stress and reduce adult lifespan by a half. In addition C. elegans exposed to 5mM lithium chloride (LiCl) showed lengthened life spans. When exposed to 10μM LiCl, reduced mortality was observed, but not with 1μM.
C. elegans has been instrumental to identify the functions of genes implicated in Alzheimer's disease, such as presenilin. Moreover, extensive research on C. elegans has identified RNA-binding proteins as essential factors during germline and early embryonic development.
While the worm has no eyes, it has been found to be sensitive to light due to a third type of light-sensitive animal photoreceptor protein, LITE-1, which is 10 to 100 times more efficient at absorbing light than the other two types of photopigments (opsins and cryptochromes)found in the animal kingdom.
C. elegans is remarkably adept at tolerating acceleration, it can withstand 400,000 g’s according to geneticists at the University of São Paulo in Brazil in an experiment 96% of them were still alive without adverse effects after an hour in an ultracentrifuge. 
C. elegans made news when specimens were discovered to have survived the Space Shuttle Columbia disaster in February 2003. Later, in January 2009, live samples of C. elegans from the University of Nottingham were announced to be spending two weeks on the International Space Station that October, in a space research project to explore the effects of zero gravity on muscle development and physiology. The research was primarily about genetic basis of muscle atrophy, which relates to spaceflight or being bed-ridden, geriatric, or diabetic. Descendants of the worms aboard Columbia in 2003 were launched into space on Endeavour for the STS-134 mission. Additional experiments on muscle dystrophy during spaceflight will be carried on board of the ISS starting in December 2018.
|NCBI genome ID|
|Genome size||101.169 Mb|
|Number of chromosomes||5 pairs of autosomes (I, II, III, IV and V) + 1 or 2 sex chromosomes (X)|
|Year of completion||1998|
|Organelle size||0,01 Mb|
C. elegans was the first multicellular organism to have its whole genome sequenced. The sequence was published in 1998, although some small gaps were present; the last gap was finished by October 2002.
Neurons of humans and C. elegans are almost identical. Both human and C. elegans neurons contain a dendrite which extends from the cell to receive neurotransmitters, and extend to the nerve ring or brain for a synaptic connection between neurons. The biggest difference is that C. elegans have motor excitatory and inhibitory neurons, known as cholingergic and gabaergic neurons, which simply act as further regulation for the tiny creature. It has no influence to the nervous system besides regulating neuron impulses.
Size and gene content. The C. elegans genome is about 100 million base pairs long and consists of six chromosomes and a mitochondrial genome. Its gene density is about one gene per five kilo-base pairs. Introns make up 26% and intergenic regions 47% of the genome. Many genes are arranged in clusters and how many of these are operons is unclear. C. elegans and other nematodes are among the few eukaryotes currently known to have operons; these include trypanosomes, flatworms (notably the trematode Schistosoma mansoni), and a primitive chordate tunicate Oikopleura dioica. Many more organisms are likely to be shown to have these operons.
Protein-coding genes. The genome contains an estimated 20,470 protein-coding genes. About 35% of C. elegans genes have human homologs. Remarkably, human genes have been shown repeatedly to replace their C. elegans homologs when introduced into C. elegans. Conversely, many C. elegans genes can function similarly to mammalian genes. The number of known RNA genes in the genome has increased greatly due to the 2006 discovery of a new class of 21U-RNA genes, and the genome is now believed to contain more than 16,000 RNA genes, up from as few as 1,300 in 2005. Scientific curators continue to appraise the set of known genes; new gene models continue to be added and incorrect ones modified or removed.
The reference C. elegans genome sequence continues to change as new evidence reveals errors in the original sequencing. Most changes are minor, adding or removing only a few base pairs of DNA. For example, the WS202 release of WormBase (April 2009) added two base pairs to the genome sequence. Sometimes, more extensive changes are made as noted in the WS197 release of December 2008, which added a region of over 4,300 bp to the sequence.
Related genomes. In 2003, the genome sequence of the related nematode C. briggsae was also determined, allowing researchers to study the comparative genomics of these two organisms. The genome sequences of more nematodes from the same genus e.g., C. remanei, C. japonica and C. brenneri (named after Brenner), have also been studied using the shotgun sequencing technique. These sequences have now been completed.
As of 2014, C. elegans is the most basal species in the 'Elegans' group (10 species) of the 'Elegans' supergroup (17 species) in phylogenetic studies. It forms a branch of its own distinct to any other species of the group.
Tc1 transposon is a DNA transposon active in C. elegans.
In 2002, the Nobel Prize in Physiology or Medicine was awarded to Sydney Brenner, H. Robert Horvitz, and John Sulston for their work on the genetics of organ development and programmed cell death in C. elegans. The 2006 Nobel Prize in Physiology or Medicine was awarded to Andrew Fire and Craig C. Mello for their discovery of RNA interference in C. elegans. In 2008, Martin Chalfie shared a Nobel Prize in Chemistry for his work on green fluorescent protein; some of the research involved the use of C. elegans.
Many scientists who research C. elegans closely connect to Sydney Brenner, with whom almost all research in this field began in the 1970s; they have worked as either a postdoctoral or a postgraduate researcher in Brenner's lab or in the lab of someone who previously worked with Brenner. Most who worked in his lab later established their own worm research labs, thereby creating a fairly well-documented "lineage" of C. elegans scientists, which was recorded into the WormBase database in some detail at the 2003 International Worm Meeting.
Calpain-5 is a protein that in humans is encoded by the CAPN5 gene.Calpains are calcium-dependent cysteine proteases involved in signal transduction in a variety of cellular processes. A functional calpain protein consists of an invariant small subunit and 1 of a family of large subunits. CAPN5 is one of the large subunits. Unlike some of the calpains, CAPN5 and CAPN6 lack a calmodulin-like domain IV. Because of the significant similarity to Caenorhabditis elegans sex determination gene tra-3, CAPN5 is also called as HTRA3.COQ7
The clk-1 (clock-1) gene encodes an enzyme (demethoxyubiquinone monooxygenase) that is necessary for ubiquinone biosynthesis in the worm Caenorhabditis elegans and other eukaryotes. The mouse version of the gene is called mclk-1 and the human, fruit fly and yeast homolog COQ7 (coenzyme Q biosynthesis protein 7).CLK-1 is not to be confused with the unrelated human protein CLK1 which plays a role in RNA splicing.Caenorhabditis elegans Cer13 virus
Caenorhabditis elegans Cer13 virus is a species of virus in the genus Semotivirus and the family Belpaoviridae. It exists as retrotransposons in the Caenorhabditis elegans genome.Caenorhabditis elegans Cer1 virus
Caenorhabditis elegans Cer1 virus is a species of retroviruses in the genus Metavirus.Caenorhabditis elegans small RNAs
Small RNAs (sRNAs) have been identified within the C. elegans genome and comparative genomics has shown that they are conserved across several nematode species. These sRNAs contain a characteristic 2,2,7-trimethylguanosine (TMG) cap structure that identifies them as non-coding RNAs that have a functional role within the cell but at present the exact function of these sRNAs is unknown. Immunoprecipitation using antibodies against TMG and RNA microarrays were used to identify these sRNA.Daf-16
DAF-16 is the sole ortholog of the FOXO family of transcription factors in the nematode Caenorhabditis elegans. It is responsible for activating genes involved in longevity, lipogenesis, heat shock survival and oxidative stress responses. It also protects C.elegans during food deprivation, causing it to transform into a hibernation - like state, known as a Dauer. DAF-16 is notable for being the primary transcription factor required for the profound lifespan extension observed upon mutation of the insulin-like receptor DAF-2. The gene has played a large role in research into longevity and the insulin signalling pathway as it is located in C. elegans, a successful ageing model organism.Daf-2
The DAF-2 gene encodes for the insulin-like growth factor 1 (IGF-1) receptor in the worm Caenorhabditis elegans. DAF-2 is part of the first metabolic pathway discovered to regulate the rate of aging. DAF-2 is also known to regulate reproductive development, resistance to oxidative stress, thermotolerance, resistance to hypoxia, and resistance to bacterial pathogens. Mutations in DAF-2 have been shown by Cynthia Kenyon to double the lifespan of the worms. In a 2007 episode of WNYC’s Radiolab, Kenyon called DAF-2 "the grim reaper gene.”Ellsworth Dougherty
Ellsworth C. Dougherty (1921-1965) was a biologist who was first to study the nematode worm Caenorhabditis elegans in the laboratory, with Victor Nigon, in the 1940s.History of research on Caenorhabditis elegans
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.Host microbe interactions in Caenorhabditis elegans
Caenorhabditis elegans-microbe interactions are here broadly defined and encompass the associations with all microbes that are temporarily or permanently living in or on this nematode. The microbes might engage in a commensal, mutualistic or pathogenic interaction with the host and include bacteria, viruses, unicellular eukaryotes, and fungi. In nature C. elegans harbours a variety of different microbes. In contrast, C. elegans strains that are cultivated in laboratories for research purposes have lost their naturally associated microbial communities and are commonly maintained on a single bacterial strain, Escherichia coli OP50.John Graham White
John Graham White (born 1943) is a Professor Emeritus of Anatomy and Molecular Biology at the University of Wisconsin–Madison.Lin-4 microRNA precursor
In molecular biology lin-4 is a microRNA (miRNA) that was identified from a study of developmental timing in the nematode Caenorhabditis elegans. It was the first to be discovered of the miRNAs, a class of non-coding RNAs involved in gene regulation. miRNAs are transcribed as ~70 nucleotide precursors and subsequently processed by the Dicer enzyme to give a 21 nucleotide product. The extents of the hairpin precursors are not generally known and are estimated based on hairpin prediction. The products are thought to have regulatory roles through complete or partial complementarity to mRNA. The lin-4 gene has been found to lie within a 4.11kb intron of a separate host gene (see also ).Lsy-6 microRNA
lsy-6 microRNA belongs to the class of miRNAs; these function to regulate the expression levels of other genes by several mechanisms. lsy-6 is a short non-coding RNA molecule and the first miRNA identified as having a role in nervous system development. It regulates left-right neuronal asymmetry in the nematode worm Caenorhabditis elegans.Rhabditidae
The Rhabditidae are a family of nematodes which includes the model organism Caenorhabditis elegans.Spermatheca
The spermatheca (pronounced plural: spermathecae ), also called receptaculum seminis (plural: receptacula seminis), is an organ of the female reproductive tract in insects, e.g. bees, some molluscs, oligochaeta worms and certain other invertebrates and vertebrates. Its purpose is to receive and store sperm from the male or, in the case of hermaphrodites, the male component of the body. Spermathecae can sometimes be the site of fertilization when the oocytes are sufficiently developed.Some species of animal have multiple spermathecae. For example, certain species of earthworms have four pairs of spermathecae—one pair each in the 6th, 7th, 8th, and 9th segments. The spermathecae receive and store the spermatozoa of another earthworm during copulation. They are lined with epithelium and are variable in shape: some are thin, heavily coiled tubes, while others are vague outpocketings from the main reproductive tract. It is one of the many variations in sexual reproduction.
The nematode Caenorhabditis elegans has two spermathecae, one at the end of each gonad. The C. elegans spermatheca is made up of 24 smooth muscle-like cells that form a stretchable tubular structure. Actin filaments line the spermatheca in a circumferential manner. The C. elegans spermatheca is used as a model to study mechanotransduction.An apiculturist may examine the spermatheca of a dead queen bee to find out whether it had received sperm from a male. In many species of stingless bees, especially Melipona bicolor, the queen lays her eggs during the provisioning and oviposition process and the spermatheca fertilizes the egg as it passes along the oviduct. The haplo-diploid system of sex determination makes it possible for the queen to choose the sex of the egg.Tc1/mariner
Tc1/mariner is a class of interspersed repeats DNA transposons. The elements of this class are found in all animals, including humans. They can also be found in protists.The class is named after its two best-studied members, the Tc1 transposon of Caenorhabditis elegans and the mariner transposon of Drosophila.Victor Nigon
Victor Marc Nigon (born 11 October 1920 in Metz, France, died 5 July 2015) was a biologist who was first to study the nematode worm Caenorhabditis elegans in the laboratory, with Ellsworth Dougherty, in the 1940s.Jean-Louis Brun, a student of Nigon, continued experiments on the 'Bergerac' variety of C. elegans.The specific epithet given to the nematode species Caenorhabditis nigoni is a tribute to Victor Nigon.WormBase
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.WormBook
WormBook is an open access, comprehensive collection of original, peer-reviewed chapters covering topics related to the biology of the nematode worm Caenorhabditis elegans (C. elegans). WormBook also includes WormMethods, an up-to-date collection of methods and protocols for C. elegans researchers.WormBook is the online text companion to WormBase, the C. elegans model organism database. Capitalizing on the World Wide Web, WormBook links in-text references (e.g. genes, alleles, proteins, literature citations) with primary biological databases such as WormBase and PubMed. C. elegans was the first multicellular organism to have its genome sequenced and is a model organism for studying developmental genetics and neurobiology.