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

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Banding with the HaeIII RE produced specific banding patterns, allowing an accurate organization of the karyotype of O.
Molecular karyotype analysis offered a much higher level of resolution than traditional cytogenetic analysis.
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The main aim of this study was to describe the mitotic chromosome number and karyotype of the tropical freshwater crayfish P.
After detailed history and examination, the current approach is to (a) identify the sex chromosome complement by karyotype analysis or FISH with X and Y probes and chromosome microarray; (b) gather additional phenotypic information by complete metabolic and endocrine testing as well as imaging studies, and (c) genetic testing for copy number variants in regions associated with known DSD genes or gene sequencing either for single candidate gene or a gene panel.
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The main differences between karyotype and CMA are that
2008) recognized as 60W the karyotype originally described by Sozen et al.
tesselatus are virtually indistinguishable from the conserved karyotype seen in all but two of the other 20 members of the Cyprinodontina so far examined.