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Biomedical subjects

S Pathak

Publications and source records attributed to S Pathak.

At least 199 records · Page 11Linked to original sources
PubMed1978

Induced Robertsonian fusions and tandem translocations in mammalian cell cultures.

Cultures of a cattle cell line and a Peromyscus eremicus cell line recovering from a pulse-treatment with mitomycin C, actinomycin D, 33258 Hoechst, and nitrosoguanidine exhibited translocations between chromosomes at the centromeric regions (Robertsonian fusions) as well as between centromere and telomere and between telomeres (tandem translocations). The frequency of Robertsonian fusions was found to be dose-dependent and duration-dependent with the mitomycin treatment. Biarmed chromosomes resulting from fusions may be monocentric or dicentric. Analyses of clones isolated from treated cells suggested that fused chromosomes may perpetuate in the cell populations.

Animals↗
PubMed1977

Distribution of constitutive heterochromatin in carnivores.

The distribution of constitutive heterochromatin (C-banding) in the genomes of nine species of Felidae, one species of Mustelidae, two species of Procyonidae, one species of Viverridae, one species of Canidae, and one species of Ursidae has been studied. In the chromosomes of several felid species the C-band is apparently absent. A few chromosomes show only telomeric staining in one arm or sometimes in both arms. Centromeric and interstitial distribution of heterochromatin has also been demonstrated in other species of Carnivors, but, in general, the C-banded material in felids is comparatively less in amount, and more weakly staining, than in other mammals. Induction of C-banding patterns in certain carnivore species is rather difficult, probably because of the minimal amount of heterochromatin present.

Animals↗
PubMed1977

Renal tubular abnormalities in a patient with the phenotypic appearance of C-trisomy mosaicism.

In 1971, SINHA et al. described a patient with isochromosomes arising from a C-group autosome. This patient had the phenotypic appearance of C-trisomy mosaicism. Six years later she presented with complaints of polydipsia and polyuria and was documented to have nephrogenic diabetes insipidus and renal tubular acidosis. The abnormal cell line of the patient had disappeared at the time of this observation.

Acidosis, Renal Tubular↗
PubMed1976

Chromosomes and DNA of Mus. The behavior of constitutive heterochromatin in spermatogenesis of M. dunni.

Using C-banded preparations of Mus dunni it is possible to study the behavior of constitutive heterochromatin in early stages of meiotic prophase. The X and the Y chromosomes, both of which contain a large amount of heterochromatin, lie apart in leptotene but move toward each other during zygotene. They then form the sex vesicle at late zygotene. In autosomes zygotene pairing appears to start from the telomeric ends. The centromere of the Y chromosome associates end-to-end with the terminal end of the long arm of the X chromosome. The autosomal heterochromatic short arms show forked morphology in certain bivalents at pachytene, suggesting probable incomplete synapsis.

Animals↗
PubMed1976

Fusion of two apparently intact human X chromosomes.

Cytological studies have been presented from a 15-year-old girl with short stature and failure of puberty. Buccal mucosa preparations revealed X-chromatin mass approximately double in size of that of a normal female. Leukocyte metaphases suggested a two cell line composition of the patient. One population of cells conformed with 45,X chromosome distribution. The chromosome complement of her other cell line had a modal number of 46. In this cell line a "C" chromosome was replaced by an exceptionally large submetacentric chromosome. This abnormal element exhibited late DNA replicating pattern. G-banding study revealed that the abnormal chromosome was produced as a result of fusion involving telomeric ends of long arms of 2 intact X chromosomes. This translocation X was bearing 2 C-banded areas; one around the centromere and the other at the distal end of the long arm. The distal C-band area did not show any evidence for centromeric function. It appears that a centromere becomes latent in the presence of another centromere in a translocation bearing 2 total chromosomes. Such a change of state in the additional centromere is vital for the stability of the translocation chromosome.

Adolescent↗
PubMed1976

An electron-microscopic study of the development of virulent and avirulent strains of Semliki forest virus in mouse brain.

Two strains of Semliki Forest Virus (SFV), the avirulent and virulent, were used to study the development of virus in both baby and adult mouse brain. The development of SFV in the brain was similar in baby and adult brain using the virulent strain and in the baby mouse brain using the avirulent strain. Mature virus could not be found in adult mouse brain using the avirulent strain. This paper shows that extracellular virus particles near the cell membrane stimulate the formation of coated vesicles and thus absorption of virus particles by the cell. It is suggested that these coated vesicles with contained virus particles are stimulated to develop nucleoid cores on their membrane forming cytopathic vacuoles, Type II (CPV-II). Excessive membrane growth takes place and the membrane of the CPV-II with the nucleoid cores invaginates to form intravacuolar tubules. It is suggested that these tubules become responsible fro the formation of mature virus particles. Thus the membrane of the CPV-II appears to be responsible for the development of both the inner core and outer coat of the virus.

Animals↗
PubMed1976

Giemsa-banding and the identification of the Y/autosome translocation in the african marsh mongoose, Atilax paludinosus (Carnivora, Viverridae).

The diploid chromosome number of 35 in the male and 36 in the female African marsh mongoose, Atilax paludinosus, has been confirmed. C- and G-banding analyses have shown that the Y chromosome is probably translocated onto the proximal end of the acrocentric partner of a heteromorphic autosomal pair (C3). The other partner is a subtelocentric with a heterochromatic short arm. During the translocation process, this short arm was removed and presumably lost. The sex determining mechanism in Atilax could be written as XX in the female and XYA-A in the male.

Animals↗
PubMed1976

Pachytene mapping of the male Chinese hamster.

Minced seminiferous tubules of male Chinese hamsters when treated with a mixture of trypsin (one part) and McCoy's 5a growth medium with 20% fetal calf serum (nine parts) at 4 degrees C, washed twice with the regular growth medium, incubated at 37 degrees C in growth medium for 4 h, and harvested without Colcemid and hypotonic pretreatments, gave excellent pachytene morphology for studies on chromomere patterns. The Giemsa banding patterns of all somatic metaphase chromosomes except the sex chromosomes of the hamster cells correspond well to the chromomere patterns of meiotic pachytene bivalents.

Animals↗
PubMed1975

A high resolution study of the DNA replication patterns of chinese hamster chromosomes using sister chromatid differential staining technique.

Chinese hamster cells were grown for 1+ and 2+ cell cycles in the presence of BrdU and then treated by the sister chromatid differential staining technique (SCD). Those regions of a chromosome which had replicated twice in the presence of BrdU were pale staining and by selecting appropriate metaphase cells an accurate reconstruction of the DNA synthetic patterns was possible. A direct correlation between the staining intensity of the G bands and the order in which they replicate was found. Dark staining G bands were always the last region of a chromosome to replicate while G negative bands were first. It is concluded that each G band may be a cluster of replicons capable of initiating DNA synthesis simultaneously.

Animals↗
PubMed1975

The possible role of histones in the mechanism of chromosomal G banding.

Cytochemical data are presented to show that the histone fractions f1 and f2a are involved in the induction of chromosomal G bands, whereas the f2b and f3 fractions are not involved. Removal of the f1 and f2a fractions probably occurs during fixation and is necessary for the induction of G bands.

Azure Stains↗
PubMed1975

A combination of sister chromatid differential staining and giemsa banding.

We report a procedure for combining sister chromatid differential staining and G banding in the same metaphase plate. Mammalian cells in culture are grown in medium containing 5-bromodeoxyuridine for two cell cycles, and conventional air-dried preparations are made. The slides are treated with a trypsin or a urea solution the same way as for regular G banding. This method is simple and fast and provides additional information for cytogeneticists.

Animals↗
PubMed1975

Actinomycin D effects on mitosis and chromosomes: sticky chromatids and localized lesions.

When Indian muntjac and Chinese hamster cells in culture were treated with Actinomycin D (1 micron/ml) for 1-2 hours, the sister chromatids, especially the distal segments, appeared to have difficulty separating in anaphase. The separated proximal segments progressively became stretched. The nucleolus organizer regions seemed to be most susceptible to stretching, and breaks in these regions were frequently observed. Electron microscopic observations showed that the sticky chromatids (and less frequently sticky chromosomes) contain connecting submicroscopic chromosome strands. When the treated cells were allowed to grow in a drug-free medium for several days, a high frequency of endoreduplicated mitotic figures was found. Chromosome and chromatid breaks and other aberrations were common, mainly localized at G band negative areas particularly nucleolus organizer regions.

Adhesiveness↗