- 1. A population of homogeneous organisms possessing a set of defined characteristics; 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. [A.S. streon, progeny] 3. To make an effort to the limit of one's strength. 4. To injure by overuse or improper use (usually refers to a muscle tear). 5. An act of straining. 6. Injury resulting from s. or overuse. [L. stringere, to draw tight] 7. The change in shape that a body undergoes when acted upon by an external force. 8. To filter; to percolate.- auxotrophic strains strains 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. SYN: pseudolysogenic s..- cell s. in tissue culture, cells derived from a primary culture or a single cell (clone) and possessing a specific feature such as a marker chromosome, antigen, or resistance to a virus.- congenic s. an 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.- 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. SYN: neotype culture.- prototrophic strains strains that have the same nutritional requirements as the wild-type s..- stock s. a bacterial or other microbial s. that has been maintained under laboratory conditions as representative of its type.- wild-type s. a s. found in nature or a standard s.. SEE ALSO: auxotrophic strains, prototrophic strains.
* * *strain 'strān n a group of presumed common ancestry with clear-cut physiological but usu. not morphological distinctions <a highly virulent \strain of bacteria>strain vt1 a) to exert (as oneself) to the utmostb) to injure by overuse, misuse, or excessive pressure <\strained his heart by overwork>c) to cause a change of form or size in (a body) by application of external force2) to cause to pass through a strainer vi to contract the muscles forcefully in attempting to defecate often used in the phrase strain at stoola) excessive physical or mental tension also a force, influence, or factor causing such tensionb) bodily injury from excessive tension, effort, or use <heart \strain> esp one resulting from a wrench or twist and involving undue stretching of muscles or ligaments <back \strain> compare SPRAINc) deformation of a material body under the action of applied forces
* * *1. n. excessive stretching or working of a muscle, resulting in pain and swelling of the muscle. Compare sprain.2. n. a group of organisms, such as bacteria, obtained from a particular source or having special properties distinguishing them from other members of the same species.3. vb. to damage a muscle by overstretching.
* * *(strān) 1. to exercise or use to an extreme, potentially harmful, degree. 2. excessive effort or undue exercise. 3. an overstretching or overexertion of some part of the musculature. to 4. filter something or subject it to colation. 5. change in the size or shape of a body as the result of an externally applied force; expressed as the fractional or percentage change in dimension resulting from the application of stress (q.v.). 6. a group of organisms within a species or variety, characterized by some particular quality, such as rough or smooth strains of bacteria.
Medical dictionary. 2011.