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Biomedical subjects

M Srivastava

Publications and source records attributed to M Srivastava.

At least 109 records · Page 6Linked to original sources

Cloning and sequencing of the human nucleolin cDNA.

A cDNA containing the entire coding region for human nucleolin has been isolated from a lambda gt10 human retinal library using a bovine cDNA probe. The cDNA hybridized to a transcript of 3000 bases from fast-dividing cells, as well as terminally differentiated tissues of several species. Translation of the nucleotide sequence revealed a long open reading frame which predicts a 707 amino acid protein with several distinct domains. These include repeating elements, four conserved RNA-binding regions, a glycine-rich carboxy-terminal domain and sites for phosphorylation, glycosylation and dibasic cleavage. Human and bovine nucleolin exhibited more additions and/or substitutions of aspartate, glutamate and serine residues in the chromatin-binding domains by comparison with the hamster and mouse nucleolins. These differences may be related to species-specific functions in transcription.

Adrenal Medulla↗

Calcium channel activity of purified human synexin and structure of the human synexin gene.

Synexin is a calcium-dependent membrane binding protein that not only fuses membranes but also acts as a voltage-dependent calcium channel. We have isolated and sequenced a set of overlapping cDNA clones for human synexin. The derived amino acid sequence of synexin reveals strong homology in the C-terminal domain with a previously identified class of calcium-dependent membrane binding proteins. These include endonexin II, lipocortin I, calpactin I heavy chain (p36), protein II, and calelectrin 67K. The Mr 51,000 synexin molecule can be divided into a unique, highly hydrophobic N-terminal domain of 167 amino acids and a conserved C-terminal region of 299 amino acids. The latter domain is composed of alternating hydrophobic and hydrophilic segments. Analysis of the entire structure reveals possible insights into such diverse properties as voltage-sensitive calcium channel activity, ion selectivity, affinity for phospholipids, and membrane fusion.

Amino Acid Sequence↗

Cytochrome b561 catalyzes transmembrane electron transfer.

Purified cytochrome b561 from bovine adrenal medulla chromaffin vesicles has been reconstituted into phosphatidylcholine vesicles by a detergent-dialysis method. When the reconstituted cytochrome-containing vesicles were preloaded with ascorbic acid and cytochrome c was added to the external medium, the internal ascorbic acid was able to reduce the external cytochrome c. This reduction of cytochrome c was dependent on the presence of cytochrome b561 in the membrane and was not due to leakage of ascorbate from the vesicles. These results demonstrate that cytochrome b561 catalyzes a transmembrane electron transfer.

Adrenal Medulla↗

Position-specific induction of benzo(a)pyrene metabolism by 3-methylcholanthrene and phenobarbital in mullet (Mugil cephalus), a marine fish.

Mullet (Mugil cephalus), a marine fish, were treated with 3-methylcholanthrene and phenobarbital by i.p. injection and the effects on the metabolism of benzo(a)pyrene by isolated liver microsomes were evaluated. The most significant effect found in treated fish was an increase in the oxidation of benzo(a)pyrene at the bay region, a position-specific increase which was not reflected in an increase in the total activity. Comparison of metabolite patterns of the dihydrodiols of benzo(a)pyrene in the presence and absence of trichloropropene oxide showed that predicted inhibitions were observed in control as well as treated animals. No significant differences in metabolite patterns were found between the 3-methylcholanthrene- and phenobarbital-treated fish in either the presence or absence of trichloropropene oxide. Comparison is made to published data on similar position-specific effects observed in rats.

Animals↗

Retinoblastoma.

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Child↗

Studies on in vitro survival of Isoparorchis hypselobagri.

Adult parasites, Isoparorchis hypselobagri were maintained in vitro in four basic salt solutions, viz. Stephenson saline, AB saline, Tyrode's solution and Locke's solution. Survival was prolonged by adding sugars to Tyrode's solution. Of all the sugars, glucose was found most effective and parasites survived for 39 days in solution containing glucose, 6 days in galactose and sucrose, 10 days in fructose and lactose and 12 days in maltose. The parasites absorb carbohydrates through the cuticle. Ligated parasites survived for a longer period than unligated parasites. The pH 9 was considered as an optimum for maximum survival of the parasites Isoparorchis hypselobagri for 39 days.

Absorption↗

Protein metabolism in Isoparorchis hypselobagri.

Isoparorchis hypselobagri was maintained in a non-nutrient medium containing streptomycin and penicillin to prevent bacterial growth for a period of 12 hours. The parasites were kept under aerobic conditions at a suitable temperature of 30 degrees C. The protein content in Isoparorchis hypselobagri ranged from 56.25% to 67.5% with an average of 63.5%+/-4.6 of dry seight of the tissue. The nitrogen of Isoparorchis hypselobagri excreted as ammonia, after 12 hours of starvation was 3.04% of the total body nitrogen and as uric acid 1.6% of total body nitrogen.

Aerobiosis↗

Amino acid composition in Isoparorchis hypselobagri.

The free amino acids of Isoparorchis hypselobagri have been determined by the chromatographic method (two-dimensional ascending). These are: leucine, valine, proline, alanine, glycine, glutamic acid and aspartic acid.

Amino Acids↗

Egg-shell formation in Isoparorchis hypselobagri.

Egg-shell formation in Isoparorchis hypselobagri is descirbed. The egg-shell in Isoparorchis hypselobagri is colorless and transparent as in case of Diplodiscus mehrai (Madhavi, 1968). Eleven histochemical tests were used to elucidate the process and it was observed that the basic mechanism of egg-shell formation followed the quinone tanned system as all the three precursors i.e. proteins, phenols and phenolase were present in vitelline globules.

Animals↗