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strain (stran)

1. A population of homogeneous organisms possessing a set of defined characters; in bacteriology, the set of descendants that retains the characteristics of the ancestor; members of a s. that subsequently differ from the original isolate are regarded as belonging either to a substrain of the original s., or to a new s. 2. Specific host cell(s) designed or selected to optimize production of recombinant products. 3. To make an effort to the limit of one's strength. [L. stringere, to bind] 4. To injure by overuse or improper use. 5. An act of straining. 6. Injury resulting from s. or overuse. 7. The change in shape that a body undergoes when acted upon by an external force. 8. To filter; to percolate. [A.S. stryand; streonan, to beget]
auxotrophic s.'ss.'s which are derived from the prototrophic s. but which require extra growth factors.
carrier s.a bacterial s. that is contaminated with a bacteriophage of low infectivity.pseudolysogenic s;
cell tissue culture, cells derived from a single cell (clone) and possessing a specific feature such as a marker chromosome, antigen, or resistance to a virus.
congenic inbred s. of animals produced by continued crossing of a gene of one line onto another inbred (isogenic) line.
HFR s., Hfr s.a s., or clone, in which a conjugative plasmid (such as an F´), integrated in the bacterial genome, is instrumental in the transfer (along with plasmid DNA) of integrated bacterial DNA in a sequential manner to a suitable recipient. [high freguency of recombination]
hypothetical mean s. (HMS) a hypothetical s. that possesses the characteristics of a calculated mean organism.
isogenic s.a s. of animals inbred for many generations and with high probability homozygous for certain specified genes.
lysogenic s.a s. of bacterium that is infected with a temporate bacteriophage. See lysogeny.
neotype s.a s. accepted by international agreement to replace a type s. which is no longer in existence or to serve as the type s. if a type s. was not designated and if no s. exists which can be designated as the type.neotype culture;
prototrophic s.'ss.'s that have the same nutritional requirements as the wild-type s.
pseudolysogenic s.carrier s
recombinant s. See recombinant (1) .
stock s.a bacterial or other microbial s. that has been maintained under laboratory conditions as representative of its type.
type s.the nomenclatural type of a species or subspecies.
wild-type s.a s. found in nature or a standard s. See also auxotrophic s.'s, prototrophic s.'s.


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