| 释义 |
polysomic, n. and a. Cytology.|pɒlɪˈsəʊmɪk|
[f. poly- + -some4 + -ic.]
A. adj. Having one or a few normal chromosomes in excess of the usual diploid or polyploid complement; being such a chromosome.
B. n. A polysomic organism.
1932C. D. Darlington Rec. Adv. Cytol. iii. 66 Polysomic forms arise in a diploid through two daughter chromosomes passing to the same pole at mitosis, or at meiosis. 1937T. Dobzhansky Genetics & Origin of Species iv. 80 Spontaneous polysomics, monosomics, polyploids, haploids, and translocations were observed in Datura stramonium by Blakeslee (1922). 1939Jrnl. Genetics XXXVIII. 409 All five asynaptic polysomics possessed three extra chromosomes. 1949R. A. Fisher Theory of Inbreeding iv. 78 Polysomic organisms differ from disomic in having more than two chromosomes mutually homologous and capable of pairing, and of interchange of segments. 1949K. Mather Biometrical Genetics x. 305 A general treatment of polysomic inheritance has not been attempted because of its inherent complexity. 1966J. A. Serra Mod. Genetics II. xii. 35 Cases in which one chromosome of the set becomes polysomic (above the normal number) are known in which the chromosome remains euchromatic and other cases in which it is heterochromatinized. Genetic imbalance and diminished viability or more or less marked lethality accompany, as a rule, the cases of polysomy when the chromosome remains euchromatic, while heterochromatic supernumeraries do not, in general, produce such effects and, probably, are of use to the cell. |