Human Acrocentric Chromosomes Research Articles

Silver staining for the analysis of rearrangements of human acrocentric chromosomes.

Silver staining for the analysis of rearrangements of human acrocentric chromosomes.

Frequency of RFA colour polymorphisms of human acrocentric chromosomes in caucasians: interrelationship with QFQ polymorphisms.

One hundred normal caucasians were studied by sequential QFQ and RFA in order to estimate the type and frequency of variation. Colour variants were classified into 1 of 6 colours by RFA and intensity variations into 1 of 5 levels by QFQ. The interrelationship between QFQ and RFA variants was also examined. It was found that there was no consistent relationship between negative or brilliant QFQ variants and the various colours observed with RFA. RFA colour polymorphisms for chromosomes 13, 14, 15, 21 and 22 were 33.0, 38.0, 28.0, 50.0 and 24.5% while QFQ frequencies were 56.5, 10.0, 10.0, 15.5 and 10.0% respectively. RFA is especially useful in studying the inheritance of chromosome 21.

Intersatellite connections of human acrocentric chromosomes in associations

Associations of chromosomes were discovered from the existence of intersatellite connections. Hypotheses regarding their hypergeometric, binomial, Poisson, uniform, and exponential distributions were rejected after testing statistical hypotheses for the quantitative distribution of chromosomes of the D and G groups in associations. Agreement between corresponding discrete points of empirical frequencies and theoretical frequencies calculated by the normal law of distribution is explained by differences in the associative power of chromosomes within the D and G groups. The basic numerical characteristics of the quantitative distribution of acrocentrics in 3- and 4-chromosome associations were calculated.

Demonstration of color and size polymorphisms in human acrocentric chromosomes by acridine orange reverse banding.

Demonstration of color and size polymorphisms in human acrocentric chromosomes by acridine orange reverse banding.

A photometric method for quantifying the polymorphisms in human acrocentric chromosomes.

Photometric measurements on photomicrographs of quinacrine mustard--stained metaphase chromosomes, processed by a reverse developing procedure provide quantitative data on the polymorphisms of human acrocentric chromosomes. The method described is intended for population studies. The method is easily reproducible, allowing comparisons of data obtained by different laboratories.

N-band polymorphism of human acrocentric chromosomes and its relevance to satellite association.

With the aid of Q- and N-banding techniques we investigated the relationship between the length of satellite stalks, the appearance of N-bands and the frequency of satellite association of individual acrocentric chromosomes in the cells of seven individuals, including one male with a satellited and small Y-chromosomes. The appearance of N-bands, seemed to be a constant and characteristic property of individual acrocentric chromosomes, independent of the status of concentration of the chromosomes at metaphase. The homolog with longer satellite stalks had larger N-bands and participated in satellite association at a higher frequency than the one with shorter stalks. It appeared that N-bands were present along the whole length of the satellite stalk, the size of which could possibly reflect the amount of rDNA present in the nucleolar organizers in human chromosomes.

Size variation polymorphisms of the short arm of human acrocentric chrosomes determined by R-banding by fluorescence using acridine orange (RFA).

One hundred normal Caucasians were studied by the RFA technique to estimate the frequencies of size variation of the short arm of acrocentric chromosomes. Each size variation was classified into one of five levels. The most frequent size level(code) was 3; therefore, this was regarded as the 'average' size. If one excludes the average size, the frequencies of size variation by RFA for chromosome 13, 14, 15, 21, and 22 were 22.5, 19.5, 14.5, 19, and 17% respectively. There was no significant difference for the overall frequencies of size variation between sexes. Furthermore, the RFA technique detects more variation in the size of human acrocentric chromosomes than any other method.

Non-random association of trypsin-banded human acrocentric chromosomes.

This paper deals with a computer-aided study of the associations between acrocentric chromosomes as well as between those other chromosomes which in our investigations were revealed to be significantly closer to each other than random. The chromosome pairs were identified by a trypsin-banding technique. The method used has been elaborated previously with the specific aim of determining associations in a manner that avoids all subjective criteria. The tendency for association between homologous chromosomes is in decreasing order: 21 and 13 greater than 1 greater than 14, 18 and 19 greater than 17. Among the nonhomologous acrocentric chromosomes the significant tendencies for associations are between D-D: 13-14 greater than 13-15 greater than 14-15; between D-G: 13-21 greater than 14-21 greater than 13-22 greater than 15-22. The implication of the different tendencies to associate are dicussed in terms of aetiology of numerical and structural chromosome abnormalities.

Analysis of the morphology of short arms of human acrocentric chromosomes by sequential staining for G and C banding

Sequential staining of acrocentric chromosomes from eight individuals for G and C banding showed that a large heterochromatin region is present more often in homologs of chromosome 15 than of 13 and 14, and in the G group it is found more often in pair 22 than in pair 21. As a rule the size of the heterocheomatin region does not correspond to the size of the short arm of the acrocentrics when stained for G banding. The frequency of occurrence of satellites in all eight individuals was approximately the same for all five pairs of acrocentrics. Staining for constitutive heterochromatin revealed heteromorphism for the presence of satellites frequently in the homologs.

Suppression of human nucleolus organizer activity in mouse-human somatic hybrid cells

Cells from four different mouse-human somatic cell hybrids were stained with quinacrine to identify each metaphase chromosome and with ammoniacal silver by the Ag-AS method to locate nucleolus organizer regions. Each of the hybrids contained human acrocentric chromosomes. None of these human acrocentric chromosomes was stained with silver in any hybrid cell. Diploid cells were available from the human parent of one of the hybrids. In these cells both copies of nos. 13 and 15 stained with silver; the same chromosomes in the hybrid cell were not stained. These results support earlier reports that the expression of human ribosomal RNA (rRNA) genes is suppressed in mouse-human hybrid cells. Further, they suggest that silver staining by the Ag-AS method reflects activity of rRNA genes rather than just the presence of these genes.

Variation in the number of genes for rRNA among human acrocentric chromosomes: correlation with frequency of satellite association

Grain counts after hybridization of 125I-rRNA to human chromosomes indicate numerical polymorphism at the rDNA sites. Prephotographing procedures decrease labeling but do not change the proportions of labeled RNA annealed to different chromosomes. A positive correlation was found between the frequency of participation of a given chromosome in satellite associations and its rDNA content by the criterion of grain count. Certain individual chromosomes are clear exceptions to this correlation.

Satellite-association frequency and rDNA content of a double-satellited chromosome.

A correlation between the amount of rDNA and the frequency of participation in satellite associations is observed in a double-satellited human acrocentric chromosome.

Differential staining of the satellite regions of human acrocentric chromosomes.

Es wird eine neue Ammoniak-Silber-Methode für das Färben menschlicher Chromosomen in der Metaphase beschrieben, wodurch die Satelliten aller 10 akrozentrischen Chromosomen zu unterscheiden sind.

Letter: Ribosomal DNA connectives between human acrocentric chromosomes.

ASSOCIATION of satellite regions of the human acrocentric chromosomes 13, 14, 15, 21 and 22 has received much attention because of its possible relation to nondisjunction, translocation and lesser structural variations, to which these chromosomes seem unusually prone. (A list of references relevant to this subject is available from the authors.) The overall frequency of associations in metaphase varies with techniques of cell culture and preparation as well as with the individual1–4. The participation of different acrocentric chromosomes is random in some people, but nonrandom in others3–13. As individual variation may account, in part, for contradictory reports concerning correlation of association characteristics with age14,15, sex4,14,17,18 and chromosomal abnormalities12–14,18–22 it is an important feature to explain.

Some aspects on the variability of the satellitized arm, in human acrocentric chromosomes.

The variability of chromatic and heterochromatic zones in human acrocentric chromosomes is studied. There is a small variability in the latter, and that of heterochromatic zones seems positively related to the participation of the chromosome in the so-called “satellited association”.

Non-random association of human acrocentric chromosomes.

The association of human acrocentric chromosomes was found to be nonrandom using fluorescence technic.

In vitro alteration of association patterns of human acrocentric chromosomes.

Association patterns of the human acrocentric chromosomes are supposed to reflect the metabolic and structural behavior of interphase nucleoli. Attempts were made to alter the association patterns by the action of chemical and physical agents (glucose, actinomycin D, temperature), which presumably influence nucleolar ultrastructur and function.

Comparative study of the association of human acrocentric chromosomes in male and female mitoses.

This paper deals with a statistical study of the spatial relationships between the acrocentric chromosomes in men and in women as can be inferred from the analysis of metaphase figures. This analysis confirms the hypothesis that the acrocentric chromosomes are not randomly situated and shows as a new fact that this effect is considerably more striking in women than in men. This might account for a part of the prominent role attributed to the mother in many cases of mongolism.

Biochemical differentiation of trisomic Down's syndrome (mongolism) from that due to translocation.

IN 1959 Lejeune, Gautier and Turpin1 observed that patients with Down's syndrome had 47 chromosomes instead of the usual 46. An extra small acrocentric chromosome, belonging to the No. 21 group, was present, producing 21. Since then, other patients with mongolism have been described with only 46 chromosomes but with translocation of chromatin material from 1 chromosome to another. If an entire chromosome is translocated an equivalent trisomy is produced. (In translocations of human acrocentric chromosomes part of the short arms may be deleted in the process of translocation.) Thus, there are at least 2 very distinct types of . . .