acrocentric chromosome

Five pairs are acrocentric chromosomes and one pair is metacentric.

Robertsonian translocations have been seen involving all combinations of acrocentric chromosomes.

This type of rearrangement involves two acrocentric chromosomes that fuse near the centromere region with loss of the short arms.

A Robertsonian translocation results when the long arms of two acrocentric chromosomes fuse at the centromere and the two short arms are lost.

In some cases, a metacentric chromosome is formed by balanced translocation: the fusion of two acrocentric chromosomes to form one metacentric chromosome.

The domestic horse genome includes one metacentric chromosome that is homologous to two acrocentric chromosomes in the conspecific but undomesticated Przewalski's horse.

C-banding stains the constitutive heterochromatin, which usually lies near the centromere, and NOR staining highlights the satellites and stalks of acrocentric chromosomes.

Ten non homologous acrocentric chromosomes in one animal correspond to five metacentric chromosomes in the other; the other eight pairs of metacentrics are common to all forms.

The autosomes include 26 pairs of acrocentric chromosomes, with a long and a very short arm, and one medium-sized submetacentric pair, with one arm shorter than the other.

One study on chromosome abnormalities in cells from persons with BS documented an elevated frequency of recombination events in the satellite stalks of acrocentric chromosomes [ 40].

In an acrocentric chromosome the p arm contains genetic material including repeated sequences such as nucleolar organizing regions, and can be translocated without significant harm, as in a balanced Robertsonian translocation.

Common Robertsonian translocations are confined to the acrocentric chromosomes 13, 14, 15, 21 and 22, because the short arms of these chromosomes encode for rRNA which is present in multiple copies.

Their children, however, may either be normal and carry the fusion chromosome (depending which chromosome is represented in the gamete), or they may inherit a missing or extra long arm of an acrocentric chromosome.

This may reflect either fixation of a balanced Robertsonian translocation in domestic horses or, conversely, fixation of the fission of one metacentric chromosome into two acrocentric chromosomes in Przewalski's horses.

The lymphocytes from this individual varied greatly with regard to the number of Q-bright satellites and which acrocentric chromosomes contained them, documenting a high frequency of recombination in the rDNA loci of BS cells.

Metaphase spreads hybridized with biotin-labeled HPV-16 probe detected with biotinyl-tyramide and streptavidin-FITC, consistently demonstrated intense signal in the central region of the long arm of an acrocentric chromosome (Figures 1Eand 1F).

A similar situation exists between the human and great ape genomes; in this case, because more species are extant, it is apparent that the evolutionary sequence is a reduction of two acrocentric chromosomes in the great apes to one metacentric chromosome in humans (see Karyotype).