Ram S. Verma

Centromeric banding (C) of sequentially Q- and R-banded human chromosomes.

SummaryA modified C-banding technique is described that produces C bands on human chromosomes after sequential Q and R banding and retains good chromosome morphology. Despite the considerable exposure to UV light during sequential Q and R bandings, clear C bands could still be achieved. Employing the present technique, Q, R, and C polymorphisms can be recorded on a single metaphase.

Size Variation Polymorphisms of the Short Arm of Human Acrocentric Chromosomes Determined by R-Banding by Fluorescence Using Acridine Orange (RFA)

SummaryOne 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.

Preferential association of nucleolar organizing human chromosomes as revealed by silver staining technique at mitosis

SummaryThe frequency of different types of satellite associations of nucleolar organizing human chromosomes (i.e. acrocentric chromosomes; 13, 14, 15, 21, and 22) is reported using 10 normal individuals by Ag-staining technique. The preferential involvement of acrocentric chromosomes in satellite association is suggested. Only acrocentric chromosomes with active NORs (i.e. Ag-stained) were found in association while unstained (inactive NORs) chromosomes were never seen in satellite association. In general as number of NORs expression increase, the frequency of association per cell was also increased. A possible mechanism and the clinical consequences of such an unusual phenophenon is described.

Population heteromorphisms of Ag-stained nucleolus organizer regions (NORs) in the acrocentric chromosomes of East Indians

SummaryThe nucleolar organizer regions (NORs) of acrocentric chromosomes in 70 normal East Indians were examined by Ag-staining (NSG) and acridine orange reverse banding (RFA) techniques. The Ag-stainability of NORs was variable from one individual to another but characteristics were constant within each individual. The average modal number of Agpositive NORs per individual was eight. A racial difference in the expression of NORs is suggested. to study the heteromorphism of NORs, the NSG technique was found to be more useful than RFA. Furthermore, it is concluded that there is no direct relationship between a heteromorphism of NORs identified by NSG and that identified by the RFA technique. Quantitative data on these differences is provided. In addition NOR-regions are classified into five sizes namely; very large, large, medium, small, and very small using subjectively defined criteria.

Effect of CO2 on short-term human lymphocyte culture in vitro.

SummaryThere was no significant difference in the mitotic indices of the cultures maintained at different CO2 concentrations, i.e. 0%, 5% and 10%. However, considerable variation was recorded among different individuals.

Human chromosomal heteromorphisms in american blacks

SummaryOne hundred normal American Blacks (B) were studied by sequential QFQ and RFA banding techniques in order to estimate the type and frequency of heteromorphisms. Color heteromorphisms were classified into one of six colors by RFA and intensity variation into one of five levels by QFQ. The data are compared with a previously studied Caucasian population (C). The frequencies of QFQ and RFA heteromorphisms were significantly higher in the Black than in the Caucasian population. No racial difference was noted for chromosome 21 by QFQ, while RFA demonstrated a clear difference. It is concluded that the maximum characterization of racial differences of human chromosomal heteromorphisms was far greater by RFA than with QFQ. The present study suggests differences in QFQ and RFA heteromorphisms among the two races.

Trisomy 21 in a child due to paternal nondisjunction as determined by RFA technique.

SummarySequential QFQ and RFA techniques were performed on a patient with Down syndrome and his parents. The paternal nondisjunctional event occurred in the first meiotic division. The origin of the extra chromosome 21 was determined by RFA. QFQ was not informative due to the absence of markers on chromosome 21. For maximal characterization of variations involving chromosome 21, sequential QFQ and RFA techniques are necessary. Consequently, the sequential QFQ and RFA techniques would be a definite asset in determining the source of the extra chromosome in patients with Down syndrome.

The quantitative analysis of constitutive heterochromatic regions of human chromosomes 1, 9, and 16 in relation to size and inversion heteromorphisms in East Indians.

100 normal East Indians were studied by C-banding technique to estimate the frequency of size and inversion heteromorphisms of the secondary constriction regions (h) of human chromosomes 1, 9, and 16, and the data were compared to those of Caucasians and Black Americans.

Chromatin of h regions of human chromosomes at high resolution.

Segmentation of the secondary constriction region (h) of human chromosomes 1, 9 and 16 is demonstrated by a high resolution banding technique. Based on these staining properties, it is suggested that the composition of theh region in human chromosomes is heterochromatic as well as euchromatic.

Human chromosomal heteromorphisms in American Blacks VII. Correlation (r) between height and the size of the Y chromosome

SummaryFifty normal American Blacks were selected to examine the correlation between the length of the Y chromosome and their height using QFQ technique. Chromosomes 19 and 20 (F group) and Y were measured directly from the film and Y/F indices were calculated as a parameter of Y length. The average length of the Y chromosome was 1.09. There was no correlation between the height of an individual with the length of his Y (p>.01). The biological and clinical significance of human Y chromosome heteromorphisms is discussed.