epistasis

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epistasis

 [ĕ-pis´tah-sis]
1. suppression of a secretion or excretion, as of blood, menses, or lochia.
2. the interaction between genes at different loci, as a result of which one hereditary character is unexpressed, or is masked by the superimposition of another upon it. See also dominance. adj., adj epistat´ic.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

e·pis·ta·sis

(e-pis'tă-sis),
1. The formation of a pellicle or scum on the surface of a liquid, especially as on standing urine.
2. Phenotypic interaction of nonallelic genes.
3. A form of gene interaction whereby one gene masks or interferes with the phenotypic expression of one or more genes at other loci; the gene the express phenotype of which is said to be "epistatic," whereas the phenotype altered or suppressed is then said to be "hypostatic."
Synonym(s): epistasy
[G. scum; epi- + G. stasis, a standing]
Farlex Partner Medical Dictionary © Farlex 2012

epistasis

(ĭ-pĭs′tə-sĭs)
n. pl. epista·ses (-sēz′)
1. An interaction between nonallelic genes in which the genotype at one locus affects the expression of alleles at another locus.
2. A film that forms over the surface of a urine specimen.
3. The suppression of a bodily discharge or secretion.

ep′i·stat′ic (ĕp′ĭ-stăt′ĭk) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

e·pis·ta·sis

(e-pis'tă-sis)
1. The formation of a pellicle or scum on the surface of a liquid, especially on standing urine.
2. Phenotypic interaction of nonallelic genes.
3. A form of gene interaction whereby one gene masks or interferes with the phenotypic expression of one or more genes at other loci; the gene with the expressed phenotype is said to be epistatic, the phenotype altered or suppressed is then said to be hypostatic.
[G. scum; epi- + G. stasis, a standing]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
Epistasisclick for a larger image
Fig. 152 Epistasis . The interaction of genes A and B.

epistasis

a form of genetic interaction in which one gene interferes with the expression of another gene, as when, for example, genes A and B code for enzymes active in the same PATHWAY. See Fig. 152 . If both ALLELES of gene A code for a nonfunctional version of enzyme A, then the pathway will shut down, irrespective of which B alleles are present, i.e. gene A is epistatic to gene B. Compare DOMINANT EPISTASIS, RECESSIVE EPISTASIS.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

e·pis·ta·sis

(e-pis'tă-sis)
Formation of a pellicle or scum on the surface of a liquid, especially as on standing urine.
[G. scum; epi- + G. stasis, a standing]
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
Higher yielding hybrids and higher yielding homozygous inbreds have been simultaneously developed by human selection for favorable additive, dominant, and epistatic genes. Heterotic groups are formed by isolation and selection for adaptedness over time.
Under two-locus additive x additive epistatic gene action, additive genetic variance is reduced either when both allele frequencies are extreme, or when they are both intermediate (Cheverud and Routman, 1996).
If favorable epistatic effects exist between loci in Parent 1 or between loci in Parent 2, and they are different sets of epistatic genes in the two parents, then one might expect the average of backcross populations to be superior to the [F.sub.3] population.
Recycling of inbreds to form new source populations could result in the loss of epistatic gene combinations through recombination, in particular if they are not tightly linked.
However, the most broadly supported theory suggests a polygenic mode of inheritance with epistatic genes, stochastic developmental events and environmental factors exerting some influence on the phenotypic expression of the genes involved [Theslef, 2000].
The actual effects of the epistatic genes often vary from the example just given, but the general control of such genes is predictable within any genetic system studied.
If Sewall Wright's shifting balance theory is plausible, then complex characters will be controlled by epistatic genes and influenced by other nonlinear components of the genetic system.
The models represent mixed action of two major additive dominant genes plus additive-dominant polygene and mixed action of two major additive dominant epistatic genes plus additive dominant epistasis of some polygene respectively (Table 3).
From the [F.sub.2] ratio it could also be inferred that there are two epistatic genes, one dominant and one recessive, governing yellow seed color in these parents.
These also have unprotected dominant I gene resistance to BCMV and complete resistance to CTV (presumed to be because of two dominant epistatic genes from A 55).