Karyotype

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karyotype

[′kar·ē·ə‚tīp]
(cell and molecular biology)
The complement of chromosomes characteristic of an individual, species, genus, or other grouping.
An organized array of the chromosomes from a single cell, grouped according to size, centromere position, and banding pattern, if any.

Karyotype

 

chromosome set, the aggregate features of the chromosomes (numaber, size, shape, details of microscopic structure) in the cells of an organism of a given species.

The concept of the karyotype was introduced by the Soviet geneticist G. A. Levitskii in 1924. The karyotype is one of the most important genetic characteristics of a species, since every species has a particular karyotype that is different from that of related species (karyosystematics, a new branch of systematics, is based on this phenomenon). The fixed nature of the karyotype in the cells of a given organism is ensured by mitosis and, within a given species, by meiosis. The karyotype of an organism may change if the gametes are altered by mutation. The karyotype of individual cells sometimes differs from the species karyotype because of chromosomal or genomic somatic mutations. The karyotype of diploid cells consists of two haploid sets (genomes) from each parent; each chromosome of such a set has a homologue from the other set. The karyotype of males may differ from that of females in the shape (sometimes also in number) of the sex chromosomes, in which case they are described separately.

The chromosomes in a karyotype are studied during the metaphase stage of mitosis. The description of a karyotype must be accompanied by a microphotograph or sketch. In systematizing karyotypes, the pairs of homologous chromosomes are arranged (for example) in order of decreasing length, beginning with the longest pair. The pairs of sex chromosomes are put at the end of the series. Pairs of chromosomes of equal length are identified by the position of the centromere (primary constriction), which divides the chromosome into two arms, by the position of the nucleolar organizer (secondary constriction), and by the shape of the satellite. The karyotypes of several thousand species of plants (wild and cultivated) and animals and man have been studied.

REFERENCES

Rukovodstvo po tsitologii, vol. 2. Edited by A. S. Troshin. Moscow-Leningrad, 1966.
Lobashev, M. E. Genetika, 2nd ed. Leningrad, 1967.

IU. F. BOGDANOV

References in periodicals archive ?
Cassileth et al., "Karyotypic analysis predicts outcome of preremission and postremission therapy in adult acute myeloid leukemia: a southwest oncology group/eastern cooperative oncology group study," Blood, vol.
Karyotypic and sperm distinction of Calomys hummelincki from Calomys laucha (Rodentia: Cricetidae).
Distribution of a supernumerary chromosomes system and aspects of karyotypic evolution in the genus Prochilodus (Pisces, Prochilodontidae).
Systematic and taxonomic implications of karyotypic, electrophoretic, and mitochondrial-DNA variation in Peromyscus from the Pacific Northwest.
One of the colonies was chosen for expansion of cells by subculture and subjected to karyotypic analysis.
In this work, we aimed to test the involvement of repetitive sequences in the karyotypic evolution of Akodontini.
Cytogenetic research efforts in blind mole rats have been rather extensive and the present review summarizes almost 100 papers reporting and describing karyotypic features of these animals across their distribution range.
It may be used as a platelets recovery marker in hematopoietic stem cell transplant recipients.9 Studies suggest that this parameter may also be used as indirect biomarker of poor prognosis in myelodysplastic syndrome with karyotypic abnotmalities.10
i(12p): A specific karyotypic abnormality in germ cell tumours.