Quantitative analysis of C bands in chromosomes 1, 9, 16 and Y in Caucasian and Japanese males

A comparative analysis of the C bands of chromosomes 1, 9, 16 and Y of 27 Caucasian and 27 Japanese males is reported. The mean of the total centromeric heterochromatin of the three pairs (sigma h1, 9, 16) is larger in Caucasian than in Japanese subjects, but Caucasians showed a lower mean of C band size of chromosome Y. Heritability of the C band of the Y chromosome was studied in 26 families.     

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16 and Y

Summary The generalized characteristic of the C-segment lengths on chromosomes 1, 9, 16, and Y is suggested for a study of population heterogeneity. For this purpose, the concept of the distance D is introduced, taking into account the individual C-segment lengths, the mean lengths and standard deviations of C-segment lengths in a group of subjects, as well as the coefficients of correlation of the C-segment lengths on the said chromosomes.It is demonstrated that distance D may be employed to study the relevance of the given subject to the group studied, the relation to the mean characteristics within the group, and selection of subjects' pairs with almost identical C-segment lengths on respective chromosomes.In the study of such problems as zygosity of twins, family analysis, etc., along with the absolute C-segment lengths, it is recommended to employ the relative C-segment lengths on chromosomes 1, 9, 16, and Y, calculated as a part of the sum total of their absolute lengths.     

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16, and Y

Summary A paracentric inversion of chromosome 5 was detected after RHG banding in a subject affected by Klinefelter's syndrome. The inversion was also observed in the patient's mother, and was confirmed by QFQ-and RBA-banding techniques.A second paracentric inversion affecting chromosome 7 was detected in a woman with Turner's syndrome. The same structural anomaly was found in her father and her half-brother.The possible relationship between sex chromosome nondisjunction and paracentric inversion is discussed.Furthermore, the inversion of chromosome 7 reproduces exactly the chromosome 7 of the gorilla, which is presumed to be ancestral to the human 7. This therefore appears to be the first reported case of reverse chromosomal mutation.     

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16, and Y

This study was made to establish a stable quantitative characteristic of C segments on chromosomes 1, 9, 16, and Y in an individual karyotype that was reproducible in successive experiments. The C segment of these chromosomes were measured in successive cultures of cells from three males and the C segments of chromosomes 1, 9, and 16 in cells from three pairs of female monozygotic twins were measured. The results show that the absolute lengths of C segments tend to vary considerably with the cell samples analyzed, while the relative length, i.e., the length of a single C segment as a percentage of the total length of all C segments of the chromosomes being studied, is more stable and can be used for individual characteristics.     

Quantitative analysis of C bands in chromosomes 1, 9, and 16 of Brazilian Indians and Caucasoids

Summary Densitometric C-band measurements in chromosomes 1, 9, and 16 of 394 Indians and 40 Caucasoids living in Brazil are reported. No significant intratribal variability in the average length of these regions was observed, and the intertribal variation showed no consistent patterns. But the Caucasoids always presented lower means. The relative C-band sizes of these three chromosomes, however, were very similar in Indians and Caucasoids. The indices of heteromorphism displayed analogous results; only in chromosome 16 are they dissimilar in these two ethnic groups. An unexpected sex difference was observed in the C-band sizes of this chromosome, females uniformly presenting higher averages than males. Centromeric heterochromatin appeared in 6% and 9% respectively of the short arms of chromosomes 1 and 9 among the Caucasoids, while among the Indians its prevalence was 2% in both chromosomes.     

Heterochromatic regions of human chromosomes 1, 9, 16 and Y and the phenotype

The relationship between variability of the heterochromatic regions of chromosomes 1, 9, 16, Y and the anthropometric characteristics (the height, the biacromial diameter and weight) was studied in two groups of children; 70 children had embryopathies of unknown etiology and 40 children had the Down syndrome. The positive statistically significant correlation of the C-segments lengths of chromosomes 1, 9, 16, their sum included, and above characteristics was found. The correlation coefficients of Y-chromosome were non-significant. The problems of functional role of the structural heterochromatin and its influence on viability and physical development of the organism are discussed.     

Relation between the size of C-segments and corresponding euchromatic regions of human chromosomes 1, 9 and 16 during their mitotic condensation

The nature of associations between the length of C-segments and the corresponding euchromatic regions of chromosomes 1, 9, and 16 in the process of their mitotic condensation has been studied. Their statistically significant linear nature in the range of chromosome 2 condensation from 11 to 4 micron has been established. Within the interval of 6.5-8.5 micron the above association is less significant, at the same time minimal variability of C-segment length is observed as compared to other stages of mitotic condensation. It is recommended to define the absolute size of C-segments in chromosomes 1, 9 and 16 by measuring their dimensions in metaphase plates with chromosome 2 length from 6.5 to 8.5 micron. The regressional correction of the results of C-segment measurements or approximation of values depending on the statistical significance of linear regression equation coefficient has been demonstrated.     

Analysis of the inheritance of heterochromatic regions in human chromosomes 1, 9, 16 and Y

The inheritance of heterochromatic regions of chromosomes 1, 9, 16 and Y was studied in twelve families by means of measuring their C-segments. Maternal and paternal origin of chromosomes 1, 9 and 16 in the child was determined by two methods. The advantages and disadvantages of these methods and possibilities of their application are under discussion.     

C-polymorphism of chromosomes 1, 9, 16 and Y in newborn infants of various gestational ages

Comparative evaluation of absolute C-segment lengths of chromosomes 1, 9, 16 and Y in new-born children of different gestational age has revealed no significant differences in their value between individuals with unfinished intrauterine development and those born in time.     

Polymorphism of human chromosomes 1, 9, 16, Y: Variations,segregation and mosaicism

Summary A study was carried out on C-banded chromosomes 1, 9, 16, Y from an unselected population and from 30 normal families. We found: a) great variability in length and position of the C-bands; b) somatic mosaicism involving C-bands; c) variants in children that were not present in parental patterns. The possible role of crossing-over in generating the last two phenomena is discussed.     

Mitomycin C induced structural changes in heterochromatic regions of human chromosomes 1, 9, 16 and Y

Aberrations and variations in the heterochromatic blocks of chromosomes 1, 9, 16 and Y were found under the influence of mitomycin C in cultured lymphocytes of peripheral human blood. Lymphocytes were cultured during 96 hours, mitomycin C in final concentration of 0.3 mkg/ml was present in the culture during the latest 24 hours of culturing. Different changes in the heterochromatic regions of chromosomes were found in approximately 30% of cells: in 6.3% of cells mitotic chiasmata were indicated. In 9.5% of cells isolocus breaks were observed in heterochromatic region of chromosome 1 in segment 1q11. In the latter case this may be a fragile site detected under the influence of mitomycin C on the lymphocytes.     

Heterochromatic regions on chromosomes 1, 9, 16, and Y in children with some disturbances occurring during embryo development

Some reduction of C-segment lengths and their variability on chromosomes 1, 9, 16, and Y was exhibited by children who had had some disturbances at early stages of morphogenesis. The data obtained might suggest a certain activity of the heterochromatic regions during embryo development. Based on this data one may also suppose that reduction of the amount of heterochromatin might affect the normal morphogenetic processes.     

Q-band chromosome polymorphism in couples with reproductive disorders

A comparative analysis of Q-band polymorphisms was conducted in phenotypically normal individuals and couples with repeated spontaneous abortions. In the group of pathology reduction of the following phenomena was found: frequencies of brilliant fluorescence in bands 4p11q11, 14p11, 14p13, 15p11, 21p13; the mean numbers of the brilliant fluorescent segments per cell per individual; frequencies of extremely large ("marker") Q-bands. All these findings coincided with our earlier published data on reduction of the C-heterochromatin amount in the same group of pathology.     

Centromeric instability of chromosomes 1, 9, and 16 associated with combined immunodeficiency

Summary Instability of the centromeric regions of chromosomes 1, 9, and 16 in cultured lymphocytes of an 8-month-old girl with malabsorption and combined immunodeficiency is reported. Together with the two previous reports on this condition, the present report seems to confirm the specific association of combined immunodeficiency and centromeric instability of chromosomes 1, 9 and 16 with multibranching.     

Multibranched chromosomes 1, 9, and 16 in a patient with combined IgA and IgE deficiency

Summary Instability of the centromeric region of chromosome 1 and multibranched configurations formed by different numbers and combinations of arms of chromosomes 1, 9, and 16 were found in cultured lymphocytes of 12-year-old male with combined IgA and IgE deficiency. No chromosome abnormalities were found in fibroblast cultures from the patient or in blood cultures from his parents.A possible effect on the frequency of the abnormalities of the almost continuous antibiotic treatment received by the patient was found both in vivo and in vitro, but no abnormalities were found in blood cultures from control subjects who received similar treatment. Interphase association of chromosomes 1, 9, and 16 and a high frequency of interchanges among the centromeric regions of these chromosomes due to the presence of a fragile site is assumed to be the cause of the abnormalities.     

Classification of qh regions in human chromosomes 1, 9, and 16 by C-banding

Summary We present a classification for secondary constriction (qh) regions with C-banding technique in chromosomes 1,9, and 16 by means of comparing them to the short arm of chromosome 16. It is simple and convenient and can be used routinely. It can be incorporated into the modified Paris nomenclature system.     

The segregation of C-band polymorphisms on chromosomes 1, 9, and 16.

Eleven normal families with at least four children were studied cytogenetically using the C-band technique to identify polymorphisms in the constitutive heterochromatin of chromosomes 1, 9 and 16. Thirteen individuals showed one or more variants in such chromosomes. The analysis of the segregation ratios in the 35 offspring of these 13 individuals showed that these marker chromosomes generally segregated according to the expected 50:50. However, one of these variants, chromosome no. 9 with an increased heterochromatin block in the secondary constriction, has an apparently preferential segregation, when the findings from this study are combined with those of other authors.     

Differential condensation of human chromosomes 9 and Y

Some differences were observed in the mitotic condensation of regions composing human chromosomes 9 and Y: regions 9p, 9h and Y nf are characterized by an intense condensation by the end of the spiralization interval studied (the length of the repair chromosome 3 varying from 5.4 to 2.9 mkm). At the same time, the condensation of regions 9q-h (region 9q without heterochromatic block) is slowing in the initial spiralization interval (the length of chromosome 3 varying from 16.6 to 5.5 mkm). The Yf-block of Y-chromosome is condensing faster than nf-region. The condensation parameters of Q-heterochromatic blocks are most variable while the euchromatic regions are most stable. The dynamics of 9h and of f-block condensation are independent within one karyotype. Based on the data obtained we doubt the correctness of studies on linear dimensions of the constitutive heterochromatin blocks for the evaluation of its quantity in the karyotype. A possible association of differential mitotic condensation with the chromosome segregation disturbances is discussed.     

Chromosomal heteromorphisms in Delhi infants. III. Qualitative analysis of C-band inversion heteromorphisms of chromosomes 1, 9, and 16

Qualitative analysis of C-band heteromorphisms was carried out in 200 infants (100 males and 100 females) in Delhi, India. Partial inversions minor and half inversions were observed as modal levels for chromosomes 1 and 9 in both sexes. No chromosome 16 with a C-band inversion was observed in the present investigation. A significantly higher incidence of percent inversions for chromosomes 1 and 9 was observed in males than in females. The frequency of heterozygous inversion level combinations for chromosome pairs 1 and 9 were remarkably higher than homozygous combinations both in males and females. Our results are compared with the other reported studies, and the possible role of these heteromorphisms in ethnic/racial variation and in developmental disturbances are discussed.