PART/CELL NAME |
ABBREVIATION
SYNONYMS (S)
ANTONYMS (A) |
LINEAGE |
DESCRIPTION |
B fiber |
B subfiber
(S) |
|
A special
form of microtubule within the ciliary axoneme (Chalfie
and Thomson, 1982). |
B cell |
|
ABprppppapa |
Rectal
epithelial cell. Postembryonic blast cell within male tail rectal epithelium. The B cell lineage contributes to the male proctodeum. |
B motor
neurons |
|
|
Class
B motorneurons are a subset of the motorneurons driving the bodywall muscles
and drive forward movement. This class of neuron includes VB and DB cells. |
"b"
neuron |
AWBL
AWBR
AWB cell (S) |
ABalpppppap
ABpraaappap |
Amphid wing "b" cells,
neurons having ciliated sheet-like sensory endings closely associated
with amphid sheath.
See AW
(Amphid wing) cell
|
Bacillary band |
|
|
A modification of the lateral (or medial) hypodermal cells in some nematode species in which non-syncytial hypodermal cells appear to have a glandular specialization, directed outwards to secrete material towards a cuticular pore (bacillary pore), perhaps involved in osmoregulation (Wright, 1963; McLaren, 1976). In some species, cells containing neurosecretory granules project ciliated endings into the bacillary band (gland cell), perhaps permitting granule release towards the pseuocoelom in response to sensory input to those cilia (Wright and Chan, 1973). |
Bacillary pore |
|
|
An elongated opening in the cuticle associated with the lateral alae in some nematode species (Wright, 1963).
See Bacillary band
|
Backcross |
|
|
A procedure
in which the progeny of a sexual mating or a new isolate from a genetic
screen is mated back into a parental strain. This procedure is commonly
used after genetic screens to obtain a desired mutation as a stable homozygote,
while eliminating any secondary mutations from its genetic composition.
Alternatively, it is used after introducing a desired mutation into a strain
via mating, to eliminate any genetic contributions from one parental strain
other than the selected mutant gene.
See Crossing
See Inbred / Inbreeding
See Outcross
|
Backing |
Backward locomotion (S)
Backing behavior (S)
Backing response (S)
Backing avoidance response
(S)
Backing reflex (S) |
|
"Backing" describes
several spontaneous and induced behaviors of C. elegans:
1) Backward locomotion; backing
behavior: Spontaneous backward crawl. Forward locomotion and backward
locomotion are antagonistic behaviors, controlled by distinct neural circuits,
although these circuits functionally interact. The neuronal circuit comprising AVA, AVD and the A motor neurons drives backward movement.
2) Backing behavior: Male specific
behavior (see mating behavior movie) where after the male's tail comes into contact with the hermaphrodite, the male backs sharply, curving his tail until his ventral side becomes apposed to the hermaphrodite. He then continues backing, sliding along the hermaphrodite's body and turning sharply near its ends (male avoids the head and tail of the hermaphrodite by turning either under or over the hermaphrodite body near but before it reaches the ends) until his tail
reaches the vulva (Barr and Garcia, 2006). The PVY interneuron is required for continued
backing.
3) Backing response; backing
avoidance response; backing reflex: Worms that bump into obstacles (e.g.
glass beads) on their paths or that are touched with a fine hair or that
encounter high osmotic strength crawl backwards typically for several
body lengths. After this, they usually turn around. This response is mediated by the mechanosensory touch neurons. |
Bacterial
lawn |
|
|
A thin film of bacteria grown
upon the surface of an agar plate as food for nematodes; this is the most
common means to raise C. elegans in the laboratory. The lawn is
usually kept from overgrowing the plate by the use of an auxotrophic strain
of E. coli (uracil-requiring), and adding a limited supply of uracil
to the plate. The lawn varies somewhat as the plate ages, growing somewhat
thicker until the uracil is exhausted, and usually becoming slightly thicker
at the border of the lawn than in the middle. There also may be subtle
differences in the lawn depending on the character of the bacterial strain;
such differences can affect some behavioral assays and nutritional studies.
See Auxotroph
|
BAG cell |
BAGL
BAGR |
ABalppappap
ABarappppap |
Neurons,
not part of any sensillum, dendrite runs along ILLso. Ciliated endings of
BAG neurons terminate in bag-shaped structures that wrap short projections
from the ILL socket cells. |
Bag of
worms |
Bag (S) |
|
A terminal phenotype in which
fertilized embryos hatch from their eggshells within the body of the hermaphrodite
and begin to feed upon the tissues of the parent animal. This process
can occur occasionally in older animals, but is very common in certain
mutants where egg-laying is inhibited by poor vulva development or inadequate
motility of the vulval muscles.
See Internal hatchees
See Oviparous
See Ovoviviparous
|
Basal
body |
|
|
A modified centriole found
distally in many sensory dendrites. The proximal segment of the ciliary axoneme, consisting of an organized
ring of microtubules lying at a local enlargement of a distal dendrite.
These structures in nematode cilia do not exactly match the organization
of classical basal bodies in motile cilia from other animals, and therefore
have sometimes been called transition zones.
Alternately, this term is often more loosely used to refer to that portion
of the cilium in which the modified centriole is located, which should
more properly be termed the transition zone.
See Axoneme
See Centriole
See Transition zone
|
Basal
lamella |
|
|
The innermost layer of the
cuticle, lying between the fiber layers and the cell membrane of the hypodermis.
See Basal zone
|
Basal
lamina |
Basement membrane (S)
Lamina (S)
Extracellular matrix (S) |
|
An extracellular
structure formed along the basal pole of the cells of a tissue. It is a
continuous layer of connective tissue over the surface of the tissue, such as hypodermis, muscle, or pharynx, uterus (ubl), and germline, and
serves to separate it from neighboring tissues. This structure consists
primarily of collagens, laminin, fibronectin, and other long chain macromolecules (See Kramer, 2005 for more detail).
In higher animals the basal lamina often consists of two or three distinct
layers, but in C. elegans it usually appears as a single homogeneous
layer which can be thick or thin depending on the tissue. The basal lamina
generally looks quite thin in cross section by TEM (after chemical fixation),
but can look more broad, fluffy or mesh-like after certain treatments (such
as high pressure freezing) or visualization by electron tomography. |
Basal
layer |
Inner layer (S)
Basal lamella (S) |
|
The innermost layer of the
cuticle is called the basal layer. It is relatively thin and may display
longitudinal striations (alternating light and dark bands; see Chitwood
and Chitwood, 1950).
See Cortical
layer
See Fiber layers
See Fibril layer
See Matrix layer
|
Basal slowing response |
|
|
A slowing in locomotion rate that occurs when well fed C. elegans encounter bacteria. This response is mediated by dopamine signaling (Sawin et al., 2000). |
Basal
zone |
Fiber layer (S)
Fiber endocuticle (S) |
|
A major
subdivision of the cuticle, consisting of three fiber layers
and a basal lamella, all of which lie innermost within the whole cuticle,
just outside the hypodermal cell membrane. Each fiber layer may contain
coherent parallel fibers running in different orientations, some in helical
bands running around the whole body, or circumferentially around the body. |
Basement
membrane |
|
|
See Basal
lamina |
BDU cell |
BDUL
BDUR |
ABarppaappp
ABarpppappp |
Neurons,
processes run along excretory canal and also in nerve ring, unique darkly
staining synaptic vesicles. |
Belt
junction |
Belt desmosome (S)
Adherens junction (S) |
|
These prominent, robust intercellular
junctions have also been called tight junctions or desmosomes; they form
continuous belts at the apical margin of lateral cell borders in most
nematode epithelia. They are tightly linked to the internal cytoskeleton
and provide strength to the tissue. They are a form of adherens junction,
but may contain some gene products that are typical of tight junctions
in higher animals.
See Adherens junction
|
Bent head |
|
|
A mutant phenotype in which the nematode exhibits a characteristic sharp kink in its head, causing misdirected body motion (Ward, 1973; Pierce-Shimomura et al., 2005).
See Adherens junction
|
Bergerac
strain |
|
|
One of the two most commonly
studied wild type strains of the nematode Caenorhabditis elegans,
originally collected from the wild in France (Nigon
and Dougherty, 1949). Reference copies are now stored frozen at the C.
elegans Stock
Center, at the University of Minnesota, to reduce the amount of possible
genetic drift from generation to generation. RW7000 subclone is used as the standard STS (sequence-tagged sites) mapping strain.
See Bristol strain
|
Bilayer |
|
|
A characteristic
feature of plasma membranes, visible in thin section by TEM, in which the
lipids, when seen in
cross-section, are organized into two discrete dark-staining layers separated by an extremely narrow clear space. The orientation of the lipids is such that non-polar
(hydrophobic) portions of the lipids are concentrated towards the middle
of the bilayer, while the polar (hydrophilic) headgroups lie
on the outward faces, exposed to the cytoplasm or the extracellular space. Proteinaceous intramembrane channels lying within the membrane can span
both lipid layers to allow passage of materials across the membrane. |
Biofilm |
|
|
A thin layer of bacteria growing on a surface, such as over the body cuticle, within the rectum or in the gut lumen. Sticky biofilms growing on the head or tail of C. elegans can cause swelling of the underlying hypodermis, interfere with feeding or defecation, and lead to delays in growth, larval arrest or death (Höflich et al., 2004). Aging nematodes often show pronounced swelling of the intestinal lumen due to infection. |
Biolistic
transformation |
|
|
A method
to create transgenic lines in C. elegans by bombardment of live animal
with DNA-coated gold microparticles (Praitis
et al., 2001). |
Bipolar |
|
|
When referring to a neuron, that which has two processes extending directly from the soma.
Alternatively, a tissue which extends two equivalent processes from a common central region. |
Birefringence |
|
|
A double refraction of light into two rays which occurs when it passes through certain types of material. In C. elegans, electron dense, birefringent structures are specifically noted in the intestine and are called gut granules. |
Blast cell |
Stem cell (S) |
|
An ancestral cell in a cell lineage that divides
once or more to give rise to several daughter cells. The daughter cells
may be of non-equivalent cell fates (as in the AB cell or the MS cell) or
of equivalent cell fates, as in a mesoblast. Later in cell lineages, the
descendants of individual blast cells may become further restricted, as
those of epidermoblasts (neuroblasts) and others. |
Blastocoel |
|
|
The fluid-filled compartment inside the developing embryo at the onset of gastrulation, surrounded by the early blastomeres, into which some cells begin to migrate at gastrulation to create a multi-layered embryo. This internal space later is converted into the pseudocoelom as the embryo develops. |
Blastomere |
|
|
Any of the early cells that
result from divisions of the fertilized oocyte. In some animal species,
all blastomeres may have equivalent genetic potential and be interchangeable.
However, in C. elegans early segregation of cytoplasmic and nuclear
determinants give each blastomere a distinct identity, non-equivalent
size and position. Early loss of any blastomere in C. elegans will
result in a dead embryo since there is virtually no means to replace its
subsequent lineage cells.
See AB
blastomere
See EMS blastomere
See Founder cell
See P blastomeres
|
Blastopore |
|
|
A hole in the ventral/posterior side of the embryo
caused by the inward flow of cells during gastrulation. It is initially
formed at the 26 cell stage by the movements of Ea and Ep. Over time,
the blastopore enlarges to form the ventral groove. |
Blastula |
|
|
The embryonic stage at which gastrulation begins.
At this time the entire embryo still consists of a single mass of cells,
except for a small internal space, the blastocoel. |
Bleb |
|
|
A small
protuberance of the cuticle in a localized spot, often near the lips or
tail tip. These often occur in certain mutant phenotypes, such as the vabs.
Alternately, a small acellular protuberance which breaks off from a cell
to create a cytoplast as viewed by light microscopy, in some mutant embryos
(Hird
and White, 1993). |
Blister |
|
|
A local
swelling or loosening of the cuticle (larger than a bleb), which can occur
anywhere along the body. These often occur in certain mutant phenotypes,
such as the vabs, or in normal animals as a precursor to a molt. |
Body
cavity neurons |
|
|
A set of sensory cells (AQR, PQR, URX) that respond to ambient levels of oxygen and whose sensilla lie close to the pseudocoelomic cavity (Cheung et al., 2004). |
Body
lobe |
|
|
See Membraneous
organelle |
Body
wall muscle |
Body
muscle (S) |
|
The principal
muscle cell type whose contractile activity generates body motion in the
nematode. They consist of 95 unfused cells in the adult organized into four
muscle quadrants. Their sarcomeres are obliquely striated and lie lengthwise
along the bodywall. Body wall muscles send muscle arms to motor neurons
to receive innervation. |
Bordering |
Bor |
|
A common behavior observed in C. elegans when grown on a culture plate. Animals move actively and stop to feed, but tend to collect preferentially on the edge (border) of the bacterial lawn, apparently where the lawn is slightly thicker. Animals (mutants) that fail to collect at the border are known as “nonBordering” animals, or Bor(-). Bordering and social feeding are thought to be under the influence of an external pheromone that is sensed by several amphid neurons (De Bono et al., 2002), and by oxygen levels monitored by body cavity sense cells (Coates and De Bono, 2002; Gray et al., 2004).
See Aerotaxis
See Pheromone
See Social feeding |
Boundary
zone |
|
|
Thin region of demarcation
within the cuticle that separates the overlying matrix layer from the
fiber layers beneath it.
See Basal zone
See Matrix layer |
Bristol
strain |
N2 (S) |
|
One of the two most commonly
studied strains of the nematode Caenorhabditis elegans, originally
collected from the wild in Bristol, England by L.N. Staniland from mushroom compost (Nicholas et al., 1959, Fatt
and Dougherty, 1963). Reference copies are now stored frozen at the C. elegans Stock Center, at the University of Minnesota, to
reduce the amount of possible genetic drift from generation to generation.
See Bergerac strain
|
Brush |
Thrush
(S) |
|
Residual
cytoplasts and/or membranous whorls and debris lying in the fan cuticle
of the male tail after retraction; most probably derive from retreating
hypodermal cells. |
Brush
border |
Bacillary
layer (archaic S) |
|
The microvillar specialization
at the apical zone of the intestine, including a densely packed set of
parallel microvilli extending into the lumen from the plasma membrane,
and a rugged layer of cytoskeletal elements which form a dense reinforcing
layer, the terminal web, just beneath the microvilli.
See Microvillus
See Terminal web
|
Buccal
capsule |
|
|
The more
anterior portions of the pharyngeal region, often subdivided into subregions
of cheilostom, prostom (arcade), mesostom, metastom and telostom. Different
authors may include all or only some of these regions when using the term. |
Buccal
cavity |
|
|
A cuticle-lined
lumenal region which lies just behind the lips at the entrance to the pharyngeal
lumen. Buccal cavity is surrounded by the pharyngeal epithelium and the
arcade cells. The buccal cavity and the pharynx are separated by a cuticular
constriction, the flaps. The nematodes food is consumed by entry into
the digestive tract through the buccal cavity. |
Buccal
epithelium |
Pharyngeal
epithelium (S) |
|
See Pharyngeal
epithelium |
Buccal
filter |
|
|
Several cuticular specializations
extend into the lumen of the pharynx and may act to trap food particles
within the central portion of the lumen during pharyngeal pumping. Three
outward channels, in turn, may permit excess fluids to be ejected from
the corners of the lumen, thus concentrating food solids.
See Channels
See Flaps
See Grinder
See Sieve
|
Bulb |
Pharyngeal
bulb (S) |
|
The tubular pharynx in C.
elegans shows two enlarged spherical regions (bulbs) along its length
which are separated by a narrower tube-shaped isthmus. First
bulb = anterior bulb = metacorpus, and second bulb = posterior bulb =
terminal bulb. In some other families of nematode, the pharynx may feature
one bulb or none.
See Isthmus
|
Bursa |
Male tail (S) |
|
The adult male tail including the the lateral fan and rays. |