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Biomedical subjects

R Raman

Publications and source records attributed to R Raman.

At least 163 records · Page 9Linked to original sources
PubMed1982

Identification and patterns of synapsis of the autosomally translocated Y-chromosome of the Indian mongoose, Herpestes auropunctatus (Hodgson).

The multiple sex chromosome system, X1X2Y male/X1X1X2X2 female, in the small Indian mongoose, Herpestes auropunctatus, results from a translocation of a part of Y chromosome to an autosome. It is not possible to distinguish the autosome which harbours the Y chromosome element in the somatic complement. By employing the surface-spreading technique to prophase I meiocytes we have identified the region to which the Y chromosome has been translocated as the short arm of chromosome 9 which is a subtelocentric chromosome. This Y chromosome component lacks heterochromatin and no sex vesicle is organised during meiotic prophase. This suggests to us that Y heterochromatin in mammals may be required for the production of a sex vesicle.

Animals↗
PubMed1981

Cytological similarity between the heterochromatin of the large x and y chromosomes of the soft-furred field rat, Millardia meltada (family: muridae).

Patterns of DNA replication, fluorescence, and meiotic pairing have been studied in the composite X and Y chromosomes of a rodent, the soft-furred field rat, Millardia meltada. The heterochromatin of both the chromosomes replicated during late S and fluoresces brightly with Netropsin-Olivomycin. The fluorescence with Actinomycin D-Hoechst is dull, suggesting that the heterochromatin of both the X and the Y is relatively GC-rich. When surface-spread testis cells are analyzed after silver staining considerable portions of the X and Y exhibit synapsis. On the basis of this study it appears that the heterochromatin of the X chromosome of M. meltada is substantially similar to that of the Y chromosome.

Animals↗
PubMed1977

Preferential late replication of one of the two morphologically distinguishable X-chromosomes in a female muntjac.

In a female barking deer, Muntiacus muntjak, whose 2 X-chromosomes are mutually distinguishable from each other, one X has been found to be late replicating in 57.8% cells compared to the other which is late replicating in 42.2% cells. These data are suggestive of preferential inactivation of one X-chromosome. These findings have been discussed in the light of Lyon's hypothesis of random X-inactivation in eutherian mammals.

Animals↗
PubMed1976

Unique multiple sex chromosomes of the tree mouse Vandeleuria o. oleracea: identification of X1 and X2.

The tree mouse Vandeleuria o. oleracea has an odd diploid chromosome complement (2n = 29 female/male) accompanied by a unique multiple sex-chromosome mechanism (X1X2Ymale/X1X1X2female). In the present paper the sex chromosomes have been identified unequivocally with the help of G-banding and DNA replication patterns which confirm our earlier suggestion that the X1 is smaller in size than the simple mammalian X, and also that the combined sizes of the X1 and X2 (3-8 and 1-7 per cent respectively) approximate to the size of the conservative mammalian X (5 per cent). It is proposed that the mammalian X has attained a minimum functional size so that further reduction is not tolerated.

Animals↗
PubMed1969

Splenic bruit.

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Adolescent↗