Centromere


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centromere

[′sen·trə‚mir]
(cell and molecular biology)
A specialized chromomere to which the spindle fibers are attached during mitosis. Also known as kinetochore; kinomere; primary constriction.

Centromere

 

a part of a chromosome that plays a fundamental role in its movement during cell division (mitosis). In the metaphase stage of mitosis, the area of the centromere within the chromosome is less dense than the chromosome’s other areas and forms a primary constriction that divides the chromosome into two sections; the position of this constriction is a basis for the classification of chromosomes. The cytoplasmic filaments (microtubules) of the spindle of cell division are attached to the centromere by their ends.

Some organisms, such as members of the genus Luzula and the scorpion, have polycentromeric chromosomes with a diffuse centromere and with the spindle filaments attached to the chromosome along its entire length. With a light microscope a cluster of chromomeres may be seen near the centromere of a chromosome during metaphase. Examination of mammalian cells with an electron microscope reveals a three-layered structure near each of the two longitudinal chromosome filaments, or chromatids. This structure is a kinetochore plate, whose interaction with the spindle filaments results in the even distribution of chromosomes among the daughter cells during cell division. Chromosomal aberrations involving the chromomere hamper the distribution of chromosomal material during mitosis and meiosis and alter the organism’s karyotype. Chromosomes that lack a centromere cannot take part in mitosis.

I. I. KIKNADZE

References in periodicals archive ?
The centromere (yellow) and the telomere (red) were considered the landmarks for the long arm.
The chromosomal analysis revealed a karyotype of 46 XY and premature centromere separation in 95.8% of the evaluated metaphase plaques.
Common immunofluorescence antinuclear antibodies patterns associated with specific diseases (6) ANA Antigen Associated pattern diseases Speckled ENA, RNP, Sm, SLE, MCTD, Ro/SSA, Systemic La/SSB, sclerosis, Scl-70, Jo-1, Sjogren's ribosomal-P syndrome, PM Homogenous dsDNA, SLE, Histones Drug-induced SLE Peripheral RNP, Sm, SLE, Systemic (rim) Ro/SSA sclerosis Nucleolar Anti-PM-Scl, Systemic anti-RNA sclerosis, polymerase PM I-III, anti-U3- RNP, To RNP Centromere CENP A-E Limited systemic sclerosis ENA: Extractable nuclear antigens; RNP: Ribonucleoproteins; SLE: Systemic lupus erythematosus; MCTD Mixed connective tissue disease; PM: Polymyositis; dsDNA: Double-stranded deoxyribonucleic acid; CENP Centromere protein.
Thus, the increase of mean chiasma frequency produced by the Spanish supernumerary segment, located interstitially on chromosome S11, is both inter- and intrachromosomal, whereas in the Austrian population, where the segment is located very close to the centromere, its influence only affects other members of the chromosome set, i.e., it is entirely interchromosomal.
Invariably associated with post-reductional meiosis in angiosperms is the absence of localized centromeres (Battaglia & Boyes, 1955).
A P1 clones (P4801) was previously assigned to the long arm of chromosome 5, immediately next to the centromere (Wang et al.
Considering the pesticide mixture used at the RF, the higher frequency of cells with chromosome breaks and asynchronic centromere segregation in animals from this area could result from the action of both clastogenic and aneugenic (spindle poison) agents.
A cutoff for RAI1 gains was not used because of the assumption that cases with gains in HER2, the centromere, and RAI1 were unlikely to represent true HER2 amplification.
That's because the centromere does not participate in the "crossover" process that occurs when cells divide to form sperm or eggs.
Interphase SRY/Y FISH was also performed on paraffin-embedded tissue obtained from the testicular-like structures in the dysgenic right gonad with locus-specific Vysis commercial FISH probes localizing to centromere X (CEPX; DXZ1; Xp11.1-q11.1 Alpha satellite DNA; Spectrum Green) and sex-determining region Y (SRY; Yp11.31-p11.32; Spectrum Aqua) and Yq12 Satellite III DNA locus (DYZ1; Spectrum Orange (Abbott Molecular, Des Plaines, IL).
In meiotic metaphase, both homologous chromosomes are paired along their longitudinal axis, pretending not to have a localized centromere. No figures that denote the presence of chiasmas were observed.