Banding Patterns Of Human Chromosomes Research Articles

Replication Banding Patterns in Human Chromosomes Detected Using 5-ethynyl-2'-deoxyuridine Incorporation

A novel technique using the incorporation of 5-ethynyl-2'-deoxyuridine (EdU) into replicating DNA is described for the analysis of replicating banding patterns of human metaphase chromosomes. Human lymphocytes were synchronized with excess thymidine and treated with EdU during the late S phase of the cell cycle. The incorporated EdU was then detected in metaphase chromosomes using Alexa Fluor® 488 azides, through the 1,3-dipolar cycloaddition reaction of organic azides with the terminal acetylene group of EdU. Chromosomes with incorporated EdU showed a banding pattern similar to G-banding of normal human chromosomes. Imaging by atomic force microscopy (AFM) in liquid conditions showed that the structure of the chromosomes was well preserved even after EdU treatment. Comparison between fluorescence microscopy and AFM images of the same chromosome 1 indicated the presence of ridges and grooves in the chromatid arm, features that have been previously reported in relation to G-banding. These results suggest an intimate relationship between EdU-induced replication bands and G- or R-bands in human chromosomes. This technique is thus useful for analyzing the structure of chromosomes in relation to their banding patterns following DNA replication in the S phase.

The nature of G-bands analyzed by chromosome stretching.

To investigate the nature of G-banding, chromosome stretching was performed on chromosome 6 at the 400-band level of normal human lymphocytes that had been cultivated and harvested using standard techniques. The GTG-banding patterns of five stretched chromosomes 6 were compared microscopically with each other and found to be identical at the 1,400-band level. A high-resolution ideogram at the 1,400-band level was constructed. The banding pattern at this level appeared to be very regular, with all dark bands at the 400-band level splitting into three to six dark subbands. While the dark subbands observed at the 1,400-band level seem to derive solely from the dark bands seen at the 400-band level, light bands visible at the 400-band level do not split into subbands, which is in contrast to the published (ISCN, 1995) ideograms. The splitting process, which was analyzed on the video monitor in more detail, shows that chromosome stretching is due mainly to the appearance of light subbands flanked by dark subbands. To shed more light on this phenomenon, the staining intensity of the dark bands and their subbands was measured while the chromosomes were stretched from the 400- to the 1,400-band level. At first, staining intensity was found to diminish in inverse proportion to the elongation of the chromosome, but then remained relatively unaffected until the dark subbands were gradually split up. After stretching to the 1,400-band level, these dark subbands were followed by newly appearing small light subbands, which were about the same size as the stretched light bands visible at the 400-band level. The results indicate that, in general, the light bands of human chromosomes are the preferentially stretched chromosome regions and that the resolution-dependent characteristic banding pattern of human chromosomes is mainly based on a fixed hierarchy of the stretchability of chromosomes.

A new banding pattern of human chromosomes by in situ nick translation using ECO RI and biotin-dUTP.

Here we present first results of an attempt to replace the nicking activity of DNAase I by ECO RI for in situ nick translation of human chromosomes. For the detection of nick translated sites we used biotinylated dUTP. The procedure resulted in a distinct banding pattern of the chromosomes which does not seem to correspond to that reached by any known banding technique.

Fluorescence banding pattern of human and mouse chromosomes with a benzimidazol derivative (Hoechst 33258).

The fluorescent banding patterns of human chromosomes and mouse chromosomes (from a tumour line MSWBS) following binding with a benzimidazol derivative (Hoechst 33258) were studied. Constitutive heterochromatic blocks in both materials fluoresced intensively with this stain. DNAase digestion or alkali denaturation and reassociation of the preparations increased the specifity of this fluorochrome to the constitutive heterochromatic blocks. The possible reasons for this differential binding of the stain to the heterochromatin are briefly discussed.

G, R and C banding patterns of human chromosomes produced by heat treatment in organic and inorganic salt solutions.

Various procedures for obtaining G, R and C bands of human chromosomes are described, all comprising treatment at 65d̀C for 22 hours in salt solutions containing different chlorides of alkaline metals, alkaline earth metals and different anions of sodium. It is concluded that the banding patterns depend upon the initial condition of the chromosomes, the pH and the kind of salt applied during the heat treatment; the pH during heat treatment depends upon the number of slides (area of exposed glass surface), temperature, duration, as well as concentration and kind of salt.

Structural basis of banding pattern of human chromosomes

Human chromosomes treated to demonstrate centromeric heterochromatin and trypsin-induced bands were observed under the scanning electron microscope and by Nomarski phase-contrast optics. The bulging appearance of the bands suggests that extracting the DNA with the proper agents will result in an alteration of the three-dimensional structure of the chromosome. The bands take up more Giemsa stain simply because of the higher density of the remaining chromatin in particular areas.

COMPARATIVE BANDING PATTERN ANALYSES IN HUMAN CHROMOSOMES INDUCED BY UREA AND TRYPSIN TREATMENTS

The present study was undertaken to compare the banding patterns of human chromosomes produced by trypsin and urea treatment techniques. Banding patterns produced by these two techniques appeared to be essentially the same and specific in each pair of homologues. These patterns also enabled the recognition of specific segments of all individual human chromosomes. From the banding pattern produced by the two techniques a diagram of the pattern was proposed by a slight modification from our previous presentation (Shiraishi and Yosida 1972).

Banding patterns in human chromosomes: production by proteolytic enzymes.

Banding patterns in human chromosomes: production by proteolytic enzymes.

Giemsa banding patterns of human chromosomes.

A method of obtaining differentially stained chromosomes is described. The method based on the treatment of the chromosomes with NaOH and subsequent incubation in phosphate buffer and Giemsa staining gave distinct banding patterns in both blood and bone marrow chromosomes. The banding patterns in some instances agreed closely with those of other methods but in others they were dissimilar. A probable explanation for the differences in banding patterns is the various treatments involved in producing banded chromosomes. While repetitive DNA may play a part in band formation, other factors may also be important.

Banding pattern analysis of human chromosomes by use of a urea treatment technique.

A new technique to reveal the banding pattern of human chromosomes is described. Slides prepared by the routine air drying technique were treated with urea-Sorensen buffer solution for ten minutes at pH 6.8 at 37° C. Individual pairs of all human chromosomes exhibited a characteristic banding pattern by this technique, and by its use the karyotypes were analysed. With the exception of some minor differences the banding patterns obtained by the present technique appeared to be identical with those obtained by the Giemsa staining and quinacrine fluorescence methods carried out by previous workers.

Specific banding patterns of human chromosomes.

Individual pairs of human chromosomes can be reliably identified by a new method that does not require special optical equipment and that results in permanent preparations. This method, which is based on treatment of the chromosomes in situ with NaOH, followed by incubation in sodium chloride-trisodium citrate and Giemsa staining, results in highly specific banding patterns in characteristic regions of the chromosome arms. It should prove useful for the detection of small structural changes in chromosomes.

A suggestion for the nomenclature of the fluorescent banding patterns in human metaphase chromosomes.

With the application of fluorescent technique, it is now possible to recognize characteristic banding patterns in human chromosomes. A simple nomenclature for the bands is suggested according to their visual identification.