| Capillitium
|
Sterile threads, which are often coiled and bear ornamentation, intermixed with spores of fruiting bodies of some Mycetozoa. Differentiated prior to complete spore cleavage, these threads aid in spore dispersal. Among higher fungi the term is not restricted to extracellular material, but can describe specialized hyphae in frutifications such as those in puff-balls. The term “elaters” is sometimes used for capillitial strands that are short and unbranched. [Link to this definition]
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| Capsular wall
|
An organic wall in actinopods, especially radiolaria, composed of closely spaced plates deposited within cytoplasmic lacunae or alveoli at the periphery of the central, more dense cytoplasm. Cytoplasmic projections protrude through pores in the wall. In myxozoan spores, the polar capsular wall consists of two layers with varying sensitivities to chemical digestion which can be observed with transmission electron microscopy; the inner electron-lucent layer resists alkaline hydrolysis and the outer electron-dense layer is digested with proteases. The thickness and organization of the wall material varies among actinopod species, and the penetrating cytoplasmic strands vary in complexity and function among major groups. See also, Capsule. [Link to this definition]
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| Capsule
|
A perforated organic layer surrounding the cell body of heliozoa, but not necessarily enclosed within a cytoplasmic envelope. Capsule and capsular wall are sometimes used synonymously for the organic wall surrounding radiolarian or clathruline heliozoan bodies, but it is preferable to separate them based on morphological differences between the wall of radiolaria (capsular wall) and the more loosely organized structure of heliozoa (capsule). A special type of extrusive organelle found in myxozoa is termed “polar capsule”. Some bacteria and yeast are surrounded by a protective organic wall, also known as a “capsule”. Case [Link to this definition]
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| Cartwheel
|
A hub-like central axis with radiating arm-like structures extending to the A-tubule (rarely B-tubule) of each triplet, and appearing like spokes of a wheel when the basal body/kinetosome is viewed in cross-section, located at the proximal end of a basal body/kinetosome. : Sometimes cartwheels appear to be absent; this may be an evolutionarily derived state or the result of inadequate fixation Synonyms: CW-pattern. [Link to this definition]
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| CELL
|
Mass of cytoplasm bounded by plasma membrane. Of two types, prokaryotic or eukaryotic. Eukaryotic organisms are the animals, plants, fungi and protists. Most protists are comprised of a single cell, and with protists the term 'organism' is synonymous with 'cell'. [Link to this definition]
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| Cell membrane
|
see
Plasma membrane.[Link to this definition]
|
| Cell wall
|
A mostly rigid, often multilayered structure consisting of discrete microfibrillar polysaccharides embedded in an amorphous matrix composed of polysaccharides, lipids, and proteins which together comprise an outermost layer of the cell proper. Architectural complexity and composition may vary among taxonomic groups, stages of cell development and environmental conditions. The cell wall confers shape to the cell and constrains the turgid protoplast. In addition, the cell wall (1) influences the cellular uptake of water and other molecules thereby regulating intracellular ionic and solute concentrations, (2) passively regulates secretions, (3) contains enzymes involved in the conversions of nutrients into metabolizable forms prior to entry into the cytoplasm, (4) serves as a store for carbon reserves, and (5) is involved in cell-cell interactions/ recognitions. See also, Cyst wall, Frustule, Spore wall, Wall fimbriae. [Link to this definition]
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| Cellular stalk
|
see
Stalk.[Link to this definition]
|
| CELLULOSE
|
Polysaccharide used to make walls (normally around the outside) of certain types of cell. [Link to this definition]
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| CENTRIC
|
A type of diatom exhibiting radial symmetry - e.g. Stephanodiscus and Melosira. Often forming filaments of many cells joined end to end. [Link to this definition]
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| CENTROHELID
|
A type of heliozoon, with thin parallel-sided arms and with prominent extrusomes (e.g., Acanthocystis). Arms arise from a central granule. Some of organic spicules, many with siliceous scales or spicules, rarely naked - as here, Oxnerella. [Link to this definition]
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| cf.
|
Abbreviation of Latin "confer", meaning "compare". Used in nomenclature
to indicate that a specimen is similar, but not necessarily identical, to
a named taxon. Example: "Ulothrix cf. speciosa"; the specimen resembles
but is not necessarily identical to the species Ulothrix speciosa. [Link to this definition]
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| Chitinous threads
|
Stiff, elongate fibrils of p-chitin (sometimes called chitan) that emanate from pores in the silica valves of some centric diatoms, and may extend a considerable distance from the cell surface. Chitinous threads (chitin fibrils) in diatoms originate from specialized invaginations of the plasma membrane that appear involved in fibril formation. One or occasionally two fibrils emit from a single pore, and appear to be replaced if dislodged from the surface. In some species chitin fibrils may be involved in colony formation. Chitin is also a major component of cell walls in many protists (especially fungal protists) and also occurs in loricae, thecae, and cyst walls of some algal and protozoan protists (chrysophytes, choanoflagellates, ciliates). [Link to this definition]
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| chlorophyceae algae
|
The Chlorophyceae, algae with green chloroplasts and an external cell wall made of cellulose. This group includes desmids, volvocids, filamentous green algae, and gave rise to the land plants. See filamentous green algae. [Link to this definition]
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| CHLOROPHYLL
|
A family of pigments used in photosynthesis to trap radiant energy. Normally located with chloroplasts. Chloroplasts with chlorophyll B have a bright green colour, those with chlorophylls a and c are off-green or yellow green. See Colour. [Link to this definition]
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| CHLOROPLAST
|
An organelle found in eukaryotic algae and plants (and occasionally as symbionts in certain protozoan and animal cells). The site of photosynthesis and of chlorophyll. See Colour and Chlorophyll. [Link to this definition]
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| CHONOTRICH
|
A type of ciliate found as an ectosymbiont on crustacea (Fig. **). [Link to this definition]
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| CHROMATIC ABERRATION
|
A fault in microscopes which leads to a failure for the object to imaged faithfully. Colours are poorly imaged so that the 'wrong' colour is seen or a colour may be seen when none is present. [Link to this definition]
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| CHROMOSOMES
|
Assemblages of the molecule DNA in nuclei of eukaryotic cells. Genetic information is located on chromosomes. Chromosomes of dinoflagellates have a peculiar arrangement and can be observed in living cells (Fig. [Link to this definition]
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| CHRYSOMONAD
|
A type of flagellate, autotrophic, mixotrophic or autotrophic. Plastids if present with chlorophylls a and c, with two unequal flagella. Also referred to as chrysos, or chrysophytes. [Link to this definition]
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| CHYTRIDS
|
A type of protist believed to be related to fungi. With a flagellated stage which settles on other organisms, sending a branching system of 'rhizoids' into the host cell and using them to draw up energy and nutrients. Flagellated stage with a single long posterior flagellum. [Link to this definition]
|
| Ciliary membrane
|
see
Plasma membrane.[Link to this definition]
|
| CILIUM
|
A behavioural type of eukaryotic flagellum, distinctive because they occur in large numbers, have a co-ordinated behaviour, and usually direct fluids parallel to the surface. Plural = cilia. [Link to this definition]
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| CINE
|
A means of obtaining a moving record by preserving a sequence of images on a light-sensitive emulsion (negatives). [Link to this definition]
|
| CINGULUM
|
A horizontal or spiral groove on the surface of dinoflagellate cells and in which lies a flagellum. The longitudinal groove is the sulcus. [Link to this definition]
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| CIRCUMFERENTIAL
|
Relating to the circumference, usually means passing round the cell in a plane normal to the (longitudinal) axis of the cell (as of cinglulum, above). [Link to this definition]
|
| CIRRI
|
A locomotor structure typical of hypotrich ciliates, formed from a tight cluster of individual cilia which move as a single entity. Used more for pushing against a solid substrate than against fluid water. This image is of the ventral surface of a hypotrich. [Link to this definition]
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| CLADISTICS
|
[Link to this definition]
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| CLASSIFICATION
|
[Link to this definition]
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| COCCOID
|
Rounded in shape, ball-like. This is Cyanidium, it looks like a blue green alga but is a red alga. [Link to this definition]
|
| Coccolith
|
Calcareous scale or plate-like particle deposited on the surface membrane of some prymnesiophytes (the coccolithophorids), varying in complexity and surface decoration according to species. Coccoliths are synthesized within cytoplasmic vesicles and deposited by exocytosis on the surface of the cell in an overlapping arrangement forming a coccosphere. Between 10 and 100 coccoliths comprise the coccosphere, which may range in size from 5 to 50 microns. The function of the coccosphere is not fully understood. Under certain growth conditions coccoliths are not secreted and the cells are naked. Coccoliths with little modification of the calcite crystal form are termed holococcoliths and are apparently developed at the surface of organic scales. Heterococcoliths are composed of identifiable component elements and are produced within the cell. A special terminology has been developed for various subtypes of holococcoliths (e.g., calyptroliths, crystalloliths) and heterococcoliths (e.g., cricoliths, placoliths, etc.). [Link to this definition]
|
| CODE OF NOMENCLATURE
|
One of three mutually independent sets of rules that govern the process of naming and classifying living things, and are applicable to protists or prokaryotes once thought to be protists. The International Code of Zoological Nomenclature applies to organisms "traditionally" (i.e., before the mid-20th century) considered to be animals. The International Code of Botanical Nomenclature applies to organisms traditionally considered to be plants or fungi. The International Code of Nomenclature of Bacteria governs prokaryotes. Several groups of protists, especially photosynthetic flagellates, are treated simultaneously by both codes - which can lead to the phenomenon of the same taxon having two different "correct" names. [Link to this definition]
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| COLLAR
|
A thin flange encircling a structure - as of the collar of pseudopodia around the flagellum of collar flagellates. [Link to this definition]
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| COLLAR FLAGELLATE
|
A type of flagellate, such as Monosiga. Also referred to as choanoflagellates. With single apical flagellum surrounded by a collar of fine pseudopodia. Two species evident in this picture [Link to this definition]
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| COLLECTING CANAL
|
Part of the contractile vacuole complex of certain ciliates. One or more of these structures may lead from the cytoplasm to the contractile vacuole [Link to this definition]
|
| COLONIAL
|
A type of organization in which many cells are bound together by secretions or cytoplasmic extensions. The cells are usually similar and so compete with each other for resources, but some degree of differentiation (cellular specialization) does occur in a number of colonial species. Colonies are usually spherical if planktonic or arborescent if attached. [Link to this definition]
|
| COLOUR
|
Colour in protists can be a useful diagnostic feature. It may be caused by photosynthetic pigments in chloroplasts (e.g. Fig. **), by other pigments in the cytoplasm (Fig. **), by metal salts which accumulate in secretions (e.g. Trachelomonas, Fig. **) or may be artifically created by chromatic aberration. Many colour blind people will not be able to distinguish between different pigment combinations in chloroplasts. [Link to this definition]
|
| COLOUR BLIND
|
[Link to this definition]
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| COLOURS - MONITOR
|
In order to fully appreciate the colours in images, computer monitors need to be set up or calibrated so they can discriminate among colours. Brightness and contrast settings need to be adjusted so that all of the panels in this chart - except the right most columns (all are black) look different. [Link to this definition]
|
| COLPODID
|
A type of ciliated protozoon, e.g. Colpoda [Link to this definition]
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| COMPOUND MICROSCOPE
|
A type of microscope, typically used for higher magnification light microscopy. Light is projected through the specimen which is placed on a platform (called a stage), the light is focussed on the speciment and directed along the optical axis of the microscope (as defined by the objectives) by means of a lens in the condenser below the stage. There are usually a number of objectives that project light into the eypieces - at the top of the microscope. [Link to this definition]
|
| Concentric fibers
|
Intra-axonemal structures consisting of filaments that often connect to the outer doublets of the axoneme. The filaments may be arranged as rings, a helix or a stellate structure. We distinguish at least three types of concentric fibers: (1) concentric ring fibers, (2) the transitional helix, and (3) the stellate structure. Concentric fibers are the most variable of the transitional features, and they may have evolved independently more than once. [Link to this definition]
|
| Concentric ring fibers
|
A stacked series of fine concentric rings (or possibly a helix) connecting A-tubules of the axonemal doublets. This type occurs in chytrids, ciliates, euglenids, plasmodiophoromycetes, and the amoebo-flagellate Naegleria. [Link to this definition]
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| CONDENSER
|
Part of a compound microscope situated between the light source and the specimen and used to focus light onto the specimen. The condenser is used to align the light along the optical axis of the microscope, to focus the light and to modify the light for various contrast enhancement optics - such as Phase Contrast. [Link to this definition]
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| CONJUGATION
|
A type of sexual event during which two cells fuse; may or may not lead to reproduction. Most commonly seen in the ciliates. Typically, two cells fuse near the mouth and a channel forms through which the cvells exchange genetic material. [Link to this definition]
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| Connecting fibers
|
Fibrillar or amorphous structure linking triplets of different basal bodies/kinetosomes with each other. A variety of adjectives have been used — amorphous, banded, dense, fan-shaped, fibrillar, filamentous, plate-like, striated. There is a bewildering array of these structures that defies classification, and at this time homologies between different protistan groups are uncertain. Centrin, a contractile protein, has been investigated at the molecular level and it occurs in the distal connecting fibers of many flagellate green algae. [Link to this definition]
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| CONTRACT
|
A kind of cellular motility in which the whole or part of a cell shortens at a visible rate in one or more directions. An agreement. [Link to this definition]
|
| CONTRACTILE VACUOLE
|
Part of the contractile vacuole complex, often the only part that is visible with the light- microscope. Collects fluid and periodically allows the fluid to be discharged through the cell surface. [Link to this definition]
|
| CONTRACTILE VACUOLE COMPLEX
|
An organelle involved in osmoregulation in protist cells, including contractile vacuole, spongiome (a membranous system not usually visible with the light microscope), possibly a pore, collecting canals and ampullae. [Link to this definition]
|
| convergence
|
Refers to similarity in form or other features of organisms which has been achieved independently - usually as a means of adapting the organism to a particular life style - for example the star-shape of actinophryid and centrohelid ( [Link to this definition]
|
| Copula
|
Plural: copulae. A strip of silica, usually more or less in the shape of a cigar band, found between the valves of a diatom. One or more copulae form the GIRDLE (synonym: CINGULUM) of a diatom, and serve to attach the two valves to each other. Synonym: girdle band. [Link to this definition]
|
| Cortex
|
The outer portion or layer(s) of a protist cell, including the plasma membrane but excluding secreted nonliving structures that may lie outside that membrane. In ciliates, the cortex exhibits considerable thickness, like the ectoplasm of many rhizopod amoebae, and contains the pellicular alveoli and the epiplasm as well as infraciliary organelles, notably the kinetosomes and their associated microfibrillar and microtubular structures. It also bears the cilia. In recent literature, the term “cortex” is used almost exclusively in reference to ciliates. See also, Cuticle, Pellicle. [Link to this definition]
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| Costa
|
Siliceous rib made up of costal strips which join and make up a spicular basket or basket-like lorica in members of the choanoflagellate family Acanthoecidae. Term also used for an elongated, solid thickening of the diatom valves , the “attachment band” connected at both ends to coiled filaments that confer elasticity to the cortex in acantharian actinopods, and a ridge or rib serving as an external ornament on the calcareous test of certain foraminifers, running parallel to the length or axis of the test. Within a lorica of choanoflagellates, costae are usually positioned in a plane parallel or perpendicular to the long axis of the protoplast and are called longitudinal and transverse costae, respectively. Some species may have helically or more irregularly arranged costae. For many taxa the number and organization of costae are used taxonomically. In addition to the above usage, the term “costa” is also used in certain parasitic flagellates (trichomonads) for a structure which is strictly speaking not a cell surface structure, namely a slender, rib-like structure or rod (a modified flagellar root, but not microtubular), which subtends the undulating membrane and which is often highly contractile and used in locomotion of the entire organism. The term “costa” is also widely used to describe diverse non-homologous rib-like structures in non-protist organisms, e.g., the ribs of vertebrates, the anterior vein on an insect wing, or the single midrib of a plant leaf, frond, or moss thallus. [Link to this definition]
|
| COVER SLIP TECHNIQUE
|
The cover slip technique is a simple way bto look at rich communities of microbes. Having found a good source of mud, sediment or sand, seive off large pieces of debris, place in a tray to a depth of about one centimetre, leave for a few hours to allow any water to separate, and remove with a pipette or turkey baster, then add one sheet of open-mesh lens tissue to the surface of the damp mud and add (22 mm X 22 mm No 1) coverslips, set cover lightly on dish and leave for 24-72 hours, over which times the microbes will migrate to the undersurface of the coverslip. [Link to this definition]
|
| CRAWLING
|
A type of movement in which the organism moves across the substrate while maintaining continuous contact with it. May involve no visible organelles (gliding) or cilia or flagella. [Link to this definition]
|
| CRENULATED
|
With a regularly indented margin. [Link to this definition]
|
| CRUSTACEA
|
A type of arthropod (metazoa), including copepods and ostracods. [Link to this definition]
|
| CRYPTOMONAD
|
A type of flagellate (Fig. **) with two similar flagella emerging from an anterior depression, and with extrsible ejectisomes associated with the depression. Also referred to as cryptos, and cryptophytes. [Link to this definition]
|
| Cuticle
|
In the broadest sense, a thin, cellular or non-cellular hydrophobic layer deposited on the outermost surface of the cell wall . In euglenoid flagellates this term is sometimes used synonymously with pellicle . In some protists also used as a synonym of cortex . The terms “cuticle”, “cutis”, and “pellis” are synonyms. The cuticle functions as an effective barrier to the movement of water, leaching of nutrients, and adds protection from injuries due to wind and physical abrasion. It may be present as either a non-cellular waxy layer on hyphae and spores or as a cellular layer of compressed hyphae on fruiting bodies. Multiple layers may be identified in the latter where the uppermost is referred to as the epicuticle and the next below as the subcuticle. Third and fourth layers, if present beneath the subcuticle, are the hypodermial and the subhypodermial layer, respectively. [Link to this definition]
|
| Cutis
|
see
Cuticle.[Link to this definition]
|
| CYANOBACTERIA
|
The same as blue green algae. A type of bacteria with bthe ability to carry out photosynthesis. Unlike the eukaryotic algae, they have no organelles - especially no chloroplasts. However, as illustrated by Chamesiphon, cyanobacteria may undergo cellular differentiation. [Link to this definition]
|
| CYST
|
A differentiated state in which the body is enclosed within a continuous extracellular lorica and exhibits very little activity (Figs **, **). Exploited by only some species. Often used to increase chances of survival in unfavourable conditions. [Link to this definition]
|
| Cyst wall
|
The cell wall of a cyst (a nonmotile, often dehydrated, resistant, inactive, dormant stage in the life cycle of many protists). Cyst walls or cyst membranes, sometimes multiple in number and quite complex, may bear sculpturing or protrusions of a striking nature, and sometimes may be equipped with an emergence pore (plugged or unplugged). Cysts are generally considered to serve in protection, propagation, and/or dispersal of the species. Many kinds of cysts have been described for protozoan protists alone, and very likely they are not all homologous structures. They are characteristic of numerous free-living as well as parasitic groups of protists and are useful in taxonomy. Planktonic foraminifera (e.g., Globigerinita glutinatd) are occasionally enclosed by a thickened protective wall, surrounding the shell , forming a “feeding cyst” containing undigested remains of prey such as diatom frustules. Some cysts contain a cyst plug, a non-living substance as a protective closure within the opening. The term cyst (cyst wall) is sometimes used synonymously with spore [spore wall ]. See also, Pellicle. [Link to this definition]
|
| Cytokalymma
|
A thin cytoplasmic sheath surrounding the siliceous endoskeleton of some actinopods (e.g., radiolaria) that supplies the silicate during skeletal deposition; the geometry of its internal space determines the shape of the skeleton. The cytokalymma is a dynamic structure that enlarges with the growing skeleton. By cytoplasmic streaming and changes in form, it determines the ontogenetic sequence of stages during skeletal growth. [Link to this definition]
|
| CYTOPHARYNX
|
Part of the food ingestion structures (mouth) of some cells, usually a channel of microtubules that draws newly formed food vacuoles away from the cytostome and into the cell (Fig. **). [Link to this definition]
|
| CYTOPLASM
|
The matter which makes up cells, within which organelles occur. [Link to this definition]
|
| CYTOPROCT
|
Found in some ciliates, the site at which old food vacuoles fuse with the cell surface and undigested residues are excreted. [Link to this definition]
|
| Cytoskeleton
|
Intracellular network of protein filaments that is insoluble in non-ionic detergents. The cytoskeleton gives the cell strength, rigidity and shape, and it is responsible for cell motility and intracellular movements. The cytoskeleton of flagellate/ciliate protists consists of (1) the flagellar apparatus/kinetid, and (2) cytoskeletal protein filaments not associated with the flagellar apparatus. [Link to this definition]
|
| CYTOSTOME
|
Literally, 'the cell mouth'. Only used in reference to organisms which ingest food at one or more particular locations, and then best used in reference to the region(s) of the cell surface through which food gains entry into the cell. Part of the 'mouth' structures - see also cytopharynx. [Link to this definition]
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