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 ?
(5) sSMCs can additionally be present in a karyotype of 46 normal chromosomes, in a numerically abnormal karyotype (e.g.
Karyotypes of marine mollusks in the family Haliotidae found in Thailand.
Karyotypes of Nannospalax (Palmer 1903) populations (Rodentia: Spalacidae) from central-eastern Anatolia, Turkey.
TS registration cards contained information on date of birth, age at diagnosis, karyotype, height (cm), height standard deviation (SD) [World Health Organization (WHO), 2007] (36), weight (kg), body mass index [BMI (kg/[m.sup.2])] derived from WHO percentile tables for girls of appropriate age (36) and Tanner stage of sexual development (37).
Studied species of Frieseomelita, collecton sites in Brazil, diploid number (2n) and karyotypes. Species Collecton site Frieseomelita varia Lontra - MG Frieseomelita sp.
They also proposed a new etiological classification on the basis of karyotype analysis2.
For the characterization of the karyotype were analyzed 50 mitotic metaphases (I and II).
In the five species, the X chromosome is the largest or nearly the largest element of the karyotype, and all chromosomes are biarmed.
In our study, we assessed the frequency of complex karyotypes in hematological diseases and manifestations.
Levy, "Placental histology in fetuses between 18 and 23 weeks' gestation with abnormal karyotype," American Journal of Obstetrics & Gynecology, vol.
Complex (multiple) karyotypes -5, del(5q), -7, inv(3), abnormalities of 3q, t(3;3), found mostly in higher age group have worst prognosis.3,7,13 The prognosis is worst in those who have two or more monosomies (-5, -7, -17) or one monosomywith a structural chromosomal anomaly (inv(3), t(3;3), and del(5q)).13
DAPI-banded Karyotypes and Hybrid Compatibility in Diploid and Tetraploid Taxa of Achillea Millefolium Agg.