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Biomedical subjects

S Pathak

Publications and source records attributed to S Pathak.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1975

Chromosomes and DNA of Mus: the karyotypes of M. fulvidiventris and M. dunni.

The chromosomes of the Asian mice, Mus fulvidiventris (booduga?), are typical of the Mus in general, viz., 40 telocentric chromosomes. The centromeric heterochromatin does not fluoresce brightly. The G band pattern of the euchromatin is the same as that of M. musculus. The diploid number of M. dunni is also 40, but each autosome possesses a short, heterochromatic second arm. The X chromosome is a long submetacentric, whose entire short arm and the terminal segment of the long arm are heterochromatic. The Y is a long telocentric and is heterochromatic. The G band pattern of the long arms of M. dunni involved only the addition of C bands. Mus dunni and M. booduga are sympatric in many localities in India, but they can be separated by karyological and subtle morphological differences.

Animals↗
PubMed1975

The possibility of latent centromeres and a proposed nomenclature system for total chromosome and whole arm translocations.

Translocations involving entire chromosomes or whole chromosome arms may not necessarily require deletion of a centromere. Conceivably, in the process of centromeric or telomeric fusion or of fusion of a centromere with a telomere, centromeric inactivation may occur, thus preserving both centromeres--one functional, the other latent--in the resultant translocation chromosome. If such latent centromeres exist and, in addition, are capable of being reactivated, it would explain how additional functional centromeres are acquired in the reverse process of chromosomal fission or fragmentation. A system of nomenclature is proposed for identifying the origin and nature of these chromosomal rearrangements.

Animals↗
PubMed1974

The X chromosomes of mammals: karylogical homology as revealed by banding techniques.

A comparison of the Giemsa-banding patterns of the X chromosomes in various mammalian species including man indicates that two major bands (A and B), which are resistant to trypsin and urea-treatments, are always present irrespective of the gross morphology of the X chromosomes. This is true in all mammalian species with the "original or standard type" X chromosomes (5-6% of the haploid genome) thus far analyzed. In the unusually large-sized X chromosomes the extra chromosomal material may be due either to the addition of genetically inert constitutive heterochromatin or to an X-autosome translocation. In these X chromosomes two major bands are present in the actual X-chromosome segment. Our data on C and G band patterns also support Ohno's hypothesis that the mammalian X chromosome is extremely conservative in its genetic content, in spite of its cytogenetic variability.

Animals↗