Cuiabad Aguilar virus See dAguilar virus

Culicoides A genus of minute biting flies (midges), dipteran insects in the family Ceratopogonidae, that feed on various warm-blooded animals and on mosquitoes. They transmit a number of virus infections, most notably a large number of species of Orbivirus.

culture medium A liquid or semi-solid mixture which supplies the physical conditions and substances necessary for cell growth or maintenance in vitro. All culture media must provide:

(1) The correct osmotic pressure. This is largely due to the concentration of sodium chloride, but other ions and glucose also contribute.

(2) The correct pH. This is usually obtained with bicarbonate buffer, with up to 5% carbon dioxide in the closed head-space above the medium.

(3) The necessary inorganic ions: sodium, potassium, calcium, magnesium, iron, carbonate, phosphate and sulfate.

(4) Carbohydrate, usually glucose.

(5) Amino acids. About 12 are necessary.

(6) Vitamins and growth factors. These may be provided either in the form of pure substances or as undefined products such as yeast or embryo extract.

(7) Peptides and proteins. Some cells will grow in completely defined media, but for most tissue cultures a supply of serum and peptides is necessary.

Most culture media contain phenol red to give visual indication of change of pH. Antibiotics are virtually always included to maintain sterility, although neither phenol red nor antibiotics are required for cell metabolism. See also tissue culture.

CUMC-B11 virus A strain of Hantaan virus in the genus Hantavirus.

Cupixi virus A probable species in the genus Orbivirus, isolated from phlebotomine sandflies in the Amazon region of Brazil. Antigenically related to the Changuinola virus group. Not associated with disease in humans.

curing Conversion of a lysogenic bacterial culture to a non-lysogenic state. Can occur spontaneously or can be induced, for example, by heating the culture briefly or by exposure to irradiation.

Curionopolis virus An unclassified virus isolated in the Amazon region of Brazil. Not associated with disease in humans.

CV-1 cells (CCL 70) A heteroploid cell line derived from the kidney of an adult male African green monkey, Cercopithecus aethiops, in 1964, for use in transformation studies on Rous sarcoma virus.

C value The amount of DNA (picograms per cell) in the haploid genome of a eukaryotic cell. The DNA content of diploid nuclei is the 2C value. The lack of correlation between the amount of DNA per cell and the phenotypic complexity of an organism is termed 'the C value paradox'.

cyanogen bromide A chemical which reacts with methionine, converting it to homoserine lactone, splitting the peptide chain on the C-terminal side of each methionine. It is used in studies of the structure and amino acid sequence of proteins.

cyanophage Viruses which replicate in blue-green algae.

cybrid Result of the fusion of a cell with a cytoplast. The cytoplast can transmit cytoplasmic components which may not be under the control of the cell genome. For example, intracisternal A-type virus particles can be transmitted to a cell which does not contain them by fusion of the cell with a cytoplast which does. The result of the fusion is a cybrid.

cyclical variations Many virus diseases undergo monthly or yearly cyclical variations which are not well understood, e.g. influenza occurs almost exclusively during the winter months, and Hepatitis

A virus is associated with epidemics every 5-7 years.

Dowell SF (2001) Emerg Inf Dis 7, 369

cyclic AMP A compound derived from ATP by the action of the enzyme adenyl cyclase. It is an important regulatory molecule in higher eukaryotes.

cyclins Proteins (A and B forms are known) whose levels fluctuate during the cell cycle, reaching a peak at mitosis then falling to zero. They are thought to be responsible for driving cells into the G2 phase, and so into mitosis.

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