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cis-trans test[sis trans]
a test in microbial genetics to determine whether two mutations that have the phenotypic effects, in a haploid cell or a cell with single phage infection, are located in the same gene or different genes; the test depends on the independent behavior of two alleles of a gene in a diploid cell or in a cell infected with two phages carrying different alleles.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
cis-trans testa genetic COMPLEMENTATION TEST to determine if two mutations have occurred within the same CISTRON or in adjacent cistrons. The test depends upon the two mutations being introduced into a cell at the same time. If they ‘complement’ each other by producing a WILD TYPE phenotype the mutations are in different cistrons (i.e. nonallelic). If a mutant phenotype is produced this shows the two mutations to be noncomplementary and therefore to be located in the same cistron (i.e. allelic). Two arrangements are possible in the cis-trans test (see Fig. 104 which can be carried out in a double HETEROZYGOTE individual (a HETEROKARYON in a haploid type). The more important is the transconfiguration, which is diagnostic, since two normal cistrons are present if the mutations are nonallelic (giving wild type) whereas the same cistron is mutant on both chromosomes if the mutations are allelic (giving a mutant phenotype).
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005