ABBREVIATION

SYNONYMS (S)
ANTONYMS (A)

The bundle of thick (myosin) and thin (actin) filaments running lengthwise within the sarcomere of bodywall muscles, best viewed by polarized light, or by phalloidin or antibody staining. Runs in parallel with I bands to form a series of alternating bright and dark bands (Waterston, 1988; Miller et al., 1983). The A band is brighter by polarized light, with a thin darker central stripe, the H zone; the A band contains interdigitating thick and thin filaments.

See H zone
See I band
See M line

Class A motor neurons are a subset of the ventral cord motor neurons which drive the bodywall muscles and execute backward movement. This class of neuron includes VA and DA cells.

See DA neurons
See VA neurons

AWAL
AWAR

AWA cell (S)

An early blast cell (embryonic founder cell) in the developing embryo which gives rise to many ectodermal cells, principally hypodermis, neurons and accessory cells. The daughters of the cell divisions of such a blast cell are named according to the orientation of the subsequent cell division planes, for instance: ABa and ABp are the anterior and posterior daughters of AB.
In early studies of other nematode species this blast cell was also called the S₁, or “somatic” blastomere.

Anterior body contraction. A motor step in defecation behavior in which anterior body wall muscles contract to concentrate the intestinal contents before the posterior body wall muscles contract.

See Defecation motor program
See pBoc

Condensed chromosomes that lack visible points of crossover (attachment) during meiosis, a condition that is increased in some mutants which interfere with crossovers.

See Chiasmate / Chiasmata

An abundant cytoskeletal protein in most cells, often linked to the plasma membrane and concentrated at cell junctions. Can assemble in different forms to create a mesh-like web or gel (g actin) underneath the plasma membrane, or long parallel fibers (f actin; as in muscle sarcomeres or stress fibers) stretching between distant portions of the cell. Through interactions with myosin motors and with anchoring proteins on organelles and the plasma membrane, these thin filaments help to provide the basis for cell shape changes, tissue rigidity, morphogenetic movements, and muscle contraction.

See Myosin
See Thin filament

Anterior deirid sheath cells.

See Deirid image gallery

H2 aaL
H2 aaR

Anterior deirid socket cells.

See Deirid image gallery

AJ

Belt junction (S)
Belt desmosome (S)
Zonula adherens (S)

The most common form of intercellular junction between epithelial cells in C. elegans. At high resolution these junctions display many cell specific differences in size and cell-cell spacing. This suggests that some tissues utilize AJ's in order to provide cell-cell adherence at their apical borders, while other AJ's also create a severe restriction or sealing of the extracellular space (tight junction-like) between cells. This is seen in tissues which undergo stronger forces and tend to form larger, more robust adherens junctions.

In most instances, these junctions form belt desmosomes, also known as zonula adherens, stretching along a continuous narrow border near the apical side of epithelial cells to link two neighboring cells tightly together. Spot desmosomes, also called macula adherens, are rare in C. elegans, though they have been seen in somatic sheath (Hall et al., 1999; Hall, unpublished).

Very similar structures, hemi-adherens junctions or hemidesmosomes, form as one-sided membrane appositions in epithelial cells to the cuticle.

See Hemidesmosome
See Ring and dot
See Sealing junction
See Secretory membrane
See Self-junction
See Tight junction

AFDL
AFDR

Finger cell (S)

Age-related fluorophores formed by non-enzymatic sugar addition to free amino groups of proteins followed by autocatalyzed cross-linking (Ulrich and Cerami, 2001).

See Age pigments

A social behavior in which nematodes choose to move together into a tight grouping, often to feed (De Bono et al., 2002), or perhaps as a preliminary step in sexual behavior. This is the opposite behavior from dispersal, and generally only occurs in the presence of food.

See Bordering
See Dispersal
See Pheromone
See Social feeding

Ala/e (/pl)

Small linear ridges running along the lateral lines of the cuticle, lengthwise along the body; these thickenings lie in register with the seam cells which likely produce them and are present in the cuticle of the L1, dauer and adult stages, but not in other larval stages. The alae are suspected to provide better traction when the animal generates a bodywave. Since the animal usually lies on its side, the alae are in perfect position to catch against the substrate.

Digestive tract (S)
Gastrointestinal system (S)

A chemical that affects the growth, health or behavior of a different species. Chemicals that mediate interactions within a species are called pheromones.

See Allomone
See Pheromone

A type of allelochemical that is produced and released by one individual that affects the behavior of another (Huettel, 1986). Usually this is used as a defensive mechanism by plants against insects.

See Allelochemical

Older name for amphid socket cell.

See Amphid socket cell

Amphid lining (S)
Amphid pouch (S)

A narrow enclosed space formed by the amphid sheath and socket cells. The ciliated dendrites of the amphid chemosensory neurons are bathed in the fluid in this space that is continuous with the exterior environment via the amphid pore. The space is filled with an electron dense matrix material that surrounds the cilia. A similar (narrower) phasmid channel is formed in the tail by homologous cell types. A longer, more open canal, the spicule channel, encloses the spicule in the male tail, and is again formed by a sheath and socket cell. Unlike the amphid and phasmid channels, the spicule channel is lined with cuticle.

See Phasmid channel
See Spicule channel
See Accessory cells

A large bundle of nerve processes which exit ventrolaterally from the amphid neuron cell bodies and then travel circumferentially under the ventral body muscles to reach the ventral nerve cord, where each amphid axon turns anteriorly to enter the nerve ring and deliver synaptic outputs to interneurons. The term can refer to the course of any one axon within the bundle, or to the bundle as a whole.

Because the commissure is so large and close to the cuticle, it can apparently be seen by light microscopy in larger nematodes, where it is known as the “hemizonid” (Bird and Bird, 1991).

Older name for amphid sheath cell.

See Amphid sheath cell

The tips of the sensory dendrites of the amphid cilia are exposed to the outside environment via a narrow opening in the cuticle at the lateral lips, the amphid pore. Each pore is formed by one of the amphid socket cells. The pore may be obstructed or closed in certain mutants.

See Amphid channel

Amphid sheath cell

AMshL
AMshR

Amphid gland (S)
Amphid pocket cell (S)

ABplaapaapp
ABpraapaapp

Accessory cells of the amphid sensillum. The sheath cell of the amphid is very large and contains distinctive secretory vesicles that are released into the amphid channel. This secretion may also spill out of the amphid pore to coat the nose of the animal (Bird and Bird, 1991).

See Amphid image gallery

AMsoL
AMsoR

Amphid cap cell (S)

Accessory cells of the amphid sensillum. The anterior process of this interfacial epidermal cell encircles the amphid opening on the left or right lip of the snout, binding tightly to the hypodermal cells (hyp2 and hyp3) and to the amphid sheath cell by adherens junctions.

See Amphid image gallery

Describes a species in which sexual reproduction involves the mixing of eggs and sperm from different individuals. This trait is not always true in C. elegans, since the hermaphrodite can fertilize itself by mixing germ cells produced internally.

See Automictic
See Dioecious

mu anal

Depressor ani (S)
Dorso-rectal muscle (S)

A single muscle cell lying above the anal ridge of the hermaphrodite tail that is in position to widen the anal opening for defecation. In the male tail this muscle cell becomes reorganized in the adult to open the cloaca.

See Defecation motor program

This term is a carryover from the older nematode literature, but it has rarely been used with regard to C. elegans. It refers to sensory receptors in the tail other than the phasmids, but it is not clear how broadly it applies in this species. In the hermaphrodite, the postdeirids lie somewhat too far anterior, and don’t seem to form a visible papilla when viewed by SEM so far (Hall, unpublished).

There are definitely papillae present in the developing male tail; the hook and postcloacal sensillum possibly qualify and are retained in the adult male tail, while the developing rays have an intermediate stage during late L4 in which they form papillae (Hall, unpublished).

mu sph

Rectal valve muscle (S)
Rectal sphincter muscle (S)

A smooth muscle formed by a single cell (mu sph) which encircles the rectal valve and whose contractions likely close the valve.

See Sphincter muscle
See Defecation motor program

The subdivision of M phase during mitosis or meiosis during which the chromatids separate from one another and move to the two ends of the spindle.

AC

gon herm anch

Z1.ppp or Z4.aaa

A cell in the somatic gonad that plays a key role in organizing vulval patterning and morphogenesis in the hermaphrodite; the preAC cell is the source for a secreted signal, LAG-2, which drives the AC/VU decision, which in turn determines the patterns of cell divisions among vulval precursors (reviewed by Greenwald, 1997). Through a feedback mechanism, the mature AC becomes the highest source of LAG-2 secretion, inhibiting LAG-2 production in VU.

In the male gonad, the anchor cell plays a much different role, as the gonadal leader cell during outgrowth, much as the DTC guides the outgrowth of the hermaphrodite gonad.

See AC/VU decision
See Distal tip cell
See Linker cell
See Somatic primordium

A breeding population in which males and hermaphrodites coexist (Stewart and Phillips, 2002).

See Dioecious

A complete absence of oxygen in the culture medium (0% O₂), under which C. elegans enters a reversible state of “suspended animation” or cryptobiosis (Van Voorhies and Ward, 2000; Padilla et al., 2002).  Under anoxic conditions the animals cease all movement, cell division and cell development.

See Cryptobiosis
See Hypoxia

1) A chemical compound that inhibits the effect of a ligand, hormone or drug.

2) A muscle whose contraction counteracts the contraction of another muscle.

A distinctive shape change noted in some embryonic cells just prior to ingression during gastrulation, where the apical cell cortex shortens due to actomyosin contractions (Nance et al., 2005).

The first step in molting, during which time the old cuticle separates from direct contact with the hypodermis, in order to allow for the deposition of new cuticle underneath it.

See Molt

An evolutionary term describing a derived characteristic arising in the descendents of a species making it different from its ancestors.

A common form of cell death which appears to originate as a decision within the nucleus to initiate a cascade of cellular events inside both the nucleoplasm and the cytoplasm resulting in chromatin clumping, nuclear breakdown, cell shrinkage and eventual death. Unlike necrotic cell death, apoptosis does not generally spread to neighboring cells.

See Necrosis
See Phagocytosis

A positive taxis in which the nematode reduces its probability of turning to move towards the stimulus (Miller et al., 2005).

A foraging strategy in which the animal varies its turning frequency to maximize the time spent in places where resources (food) are abundant (Hills et al., 2004). When the animal senses the presence of food, it turns often, and tends to dwell in the same region. But as the time since the last food encounter lengthens, the animal turns less often, causing it to move in a straight line towards a new locale where food may be encountered once again. In C. elegans, ARS behavior seems to be evoked by food (chemosensory) signals but not by touch, and requires glutamatergic, octaminergic and dopaminergic signaling among head neurons (Horvitz et al., 1982).

See Basal slowing response

1) Extended lobes of the gonad in both males and hermaphrodites. In hermaphrodites gonad arms include the uterus, spermatheca and gonad sheath (which together constitute the “proximal arm”) and the unsheathed germ cells and distal tip cell (which together constitute the “distal arm”). The distal and proximal arms of the gonad connect via the “loop” region.

2) Distinctive processes (muscle arms) formed by each bodywall muscle in order to reach major nerve cords where they receive all of their synaptic input from motorneurons.

The typical developmental endpoint (early zygote, lima bean stage, young L1 larva, sterile adult, etc) that is achieved for a particular mutation or condition that leads to arrested development.

See Embryonic arrest
See Monster

AS1
AS2
AS3
AS4
AS5
AS6
AS7
AS8
AS9
AS10
AS11

AS motor neurons (S)
DAS motor neurons (S)

Ventral cord motor neurons, innervate dorsal muscles, They have no ventral counterpart, and are cholinergic. Their connectivities are similar to VA neurons but receive additional synaptic input from AVB. AS neuron cell bodies lie within the ventral cord.

A family of very large parasitic nematode species, commonly studied by physiologists and pharmacologists due to the accessibility of its nerves and muscles by simple dissection.  Adult animals may range in length from 12-30 inches.

Nemathelminthes (S)
Pseudocoelomata (S)

A heterogeneous and large cluster of animals that have traditionally been classified together as a single group but later have been divided into about ten separate phyla, one of which is the Nematoda.

See Introduction to the Aschelminth Phyla

A type of learning in which two stimuli that were previously experienced simultaneously become linked in the memory, such that encountering one of these stimuli provokes the animal to react as if it has now encountered the second, associated stimulus.

Asymmetric cell divisions play an important role in establishing the three main axes of the body and for separating various cellular components that help specific cell fate (for more detail see Gönczy and Rose, 2005).

See Symmetrical cell division

Describes a species in which reproduction involves the mixing of eggs and sperm generated from the same individual. This trait is true in C. elegans hermaphrodites, which can self-fertilize by mixing germ cells produced internally.

See Amphimictic

In C. elegans, refers to any chromosome other than the X sex chromosome.

Refers to any animal that cannot supply a natural substance (such as an amino acid) necessary for its own growth, and therefore requires a nutritional supplement in order to survive and reproduce. Culture plates for C. elegans are usually made with a bacterial lawn of uracil-dependent E. coli; adding a limited amount of uracil within the medium of the culture plate forces a limit to the thickness of the lawn, since the auxotrophic bacteria fail to thrive once uracil is exhausted from the medium.

See Bacterial lawn

A behavioral term, referring to the animal’s withdrawal or retreat from the neighborhood of a repellant or negative stimulus.

See Avoidance behavior

Ring and ventral cord interneuron and an excitatory GABAergic motor neuron for rectal muscles. Makes few synapses. Functions in defecation; together with DVB, activates expulsion muscle contraction (E.p or EMC), also required for anterior body contraction (aBoc) step in defecation motor program.

See Defecation motor program

See Thermal avoidance

A sterile medium on which one can grow nematodes without the presence of whole (live) bacteria, or any other living material.

See Defined medium
See Liquid culture
See Monoxenic medium

General region where homologous chromosomes pair with one another. This region includes the axial element and proteins associated with its pairing.

See Axial element

Single proteinaceous axes of sister chromatids which polymerize in the assembly of the mature synaptonemal complex during meiotic prophase (Moses, 1968). The axial elements of homologous chromosomes become aligned and equidistantly separated by the proteins that constitute the central region of the synaptonemal complex (Zetka et al., 1999). It has been suggested that one role for the axial element is to hold the chromosome in a position so that preferred sites of exchange are exposed (Zetka et al., 1999).

See Central element
See Synaptonemal complex

A long thin process of a neuron, sometimes having distal branches, that forms synaptic outputs onto other neurons or muscles. Since many neuronal processes in C. elegans have mixed functions, not solely dendritic or axonal, these processes are more properly termed neurites.

See Dendrite
See Neurite

The mechanism by which a neuron process is stimulated to grow outward towards a particular signal or target cell, usually along the surface of a pre-existing cell or substrate. Axon outgrowth is typically led by a specialized structure, the growth cone. Dendrite outgrowth may occur by passive stretching as the animal enlarges (if the dendrite tip is well fixed to the cuticle) or by active outgrowth and guidance.

See Growth cone
See Pioneer axon

The mechanism by which a neuron produces a new axon or axon branch, usually as a new outgrowth from the cell body led by the active outgrowth of the growth cone.

See Growth cone