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Biomedical subjects

S Basu

Publications and source records attributed to S Basu.

At least 415 records · Page 23Linked to original sources
PubMed1986

Relationship between sporulation and synthesis of mycobacillin and dipicolinic acid under condition of catabolite repression in Bacillus subtilis.

Sporulation was repressed in the parent strain by various carbon sources whereas glucose-resistant mutants were resistant to them but not to glycerol 2-phosphate. Both mycobacillin and dipicolinic acid synthesis were repressed in the parent by some of the compounds tested, viz. glucose, pyruvate and glycerol 2-phosphate. However, these syntheses in the glucose-resistant mutants were not repressed by glucose and pyruvate but were repressed by glycerol 2-phosphate. The possible interrelationship between sporulation, dipicolinic acid and mycobacillin synthesis is discussed in light of these findings.

Antifungal Agents↗
PubMed1986

Stimulation of human neuroblastoma DNA polymerase alpha and primase activities by a protein factor isolated from rat liver chromatin.

Nuclear protein factor type 1 (NPF-1) that simulates IMR-32 primase-associated DNA polymerase alpha 1 and alpha 2 activities has been purified from a high-salt extract of liver chromatin from 6-month-old rats. The final purified factor lacks DNA polymerase alpha, RNA polymerase, and DNA-unwinding or topoisomerase type I activities. The stimulatory activity is destroyed by trypsin (60 min at 37 degrees C), DNase II (60 min at 37 degrees C), and heat treatment (2 min at 68 degrees C). The 125I-labeled NPF-1 does not bind to activated calf thymus DNA or poly(dC). However, it forms a ternary complex with DNA in the presence of DNA polymerase alpha-primase complex (alpha 1 and alpha 2). The ternary complex sediments on sucrose density gradient as a heavier band (11S). The NPF-1 also stimulates (2.5-fold) primase-catalyzed incorporation of GMP and dGMP from the corresponding triphosphates on poly(dC) template even in the presence of a high concentration of alpha-amanitin (400 micrograms/ml). The labeled duplex containing the poly(dC) template, [32P]-GTP, and [3H]dGTP loses 80% of the 32P label and 70% of the 3H label after treatment with 0.3 M KOH and DNase I, respectively. The products were isolated from reaction mixtures incubated with and without NPF-1 and subjected to alkaline sucrose-density-gradient sedimentation analysis. The results suggest that the rate of synthesis of DNA short chains is increased in the presence of NPF-1 without a concomitant increase in the chain length of the newly synthesized products.

Animals↗
PubMed1986

Role of selective pressure by screening organisms in the development of producer mutant isolates of different antibiotic markers.

The phenotypes of producer mutant isolates when obtained after mutagenesis of the spontaneous degenerate Aspergillus versicolor N5 by screening on Trichophyton rubrum and those on A. niger G3Br were found to be markedly different. In respect of phenotypic character anti-T. rubrum producer mutant isolates resembled the parental type more closely (which is specifically active against T. rubrum and generally against dermatophytes) than anti-A. niger mutant isolates. This clearly indicates not only the role of selective pressure of the screening organism in the development of a given producer mutant isolate but also shows the possibility of recovery of a producer type of the lost antibiotic marker.

Anti-Bacterial Agents↗
PubMed1986

Atropine-antagonized miosis induced in the goat by intravenous infusions of prostaglandin E (PGE1 and PGE2).

Effects of 30 min intravenous infusions of prostaglandin (PG) E1 (total dosage 0.07 mg kg-1), E2 and F2 alpha (total dosage 0.12 mg kg-1), respectively, were studied concomitant with measurements of renal excretion of PGF metabolites in hyperhydrated goats. None of the PGs induced any rise in rectal temperature. However, the PGEs elicited pronounced, atropine-antagonized miosis and an inhibition of the water diuresis accompanied by some increase in renal excretion of arginine vasopressin (AVP). These effects were not obtained in response to PGF2 alpha. The PGF2 alpha rapidly induced a conspicuous and long-lasting increase in the renal excretion of PGF metabolites. The corresponding effect of the PGEs was more delayed, and less than 10% of the increase obtained in response to PGF2 alpha. Nevertheless, the excretion of these metabolites in response to the PGEs was of the same magnitude as that previously observed during endotoxin fever in the goat. It is concluded that endotoxin-induced miosis and stimulation of AVP secretion previously demonstrated in the goat might well have been secondary to systemic PGE production. However, this does not seem to hold true for endotoxin-induced fever.

Alprostadil↗
PubMed1986

Selective action of mycobacillin on the cellular permeability of Aspergillus niger.

Cells of Aspergillus niger normally release not all but of some specific cell constituents viz., lysine, proline, ATP, Pi, Na+, K+ and Ca2+ in the absence of mycobacillin. Mycobacillin enhances the release of these materials without causing lysis. The time and concentration of mycobacillin for optimum release depends on the nature of the materials involved.

Adenosine Triphosphate↗
PubMed1985

Biosynthesis in vitro of disialosylneolactotetraosylceramide by a solubilized sialyltransferase from embryonic chicken brain.

A sialyltransferase involved in the biosynthesis in vitro of LD1c (NeuAc alpha 2-8NeuGc alpha 2-3Gal beta 1-4Glc-NAc beta 1-3Gal beta 1-4Glc-Cer) has been characterized from 9 to 11-day-old embryonic chicken brains. The CMP-[14C]NeuAc:LM1(alpha 2-8)sialyltransferase (SAT-2) sedimented (75%) at the junction of 0.75 and 1.2 M on a discontinuous sucrose density gradient when still membrane bound. In addition to the biosynthesis of LD1c, the detergent-solubilized (0.4% Nonidet P-40) preparation also catalyzes the transfer of sialic acid to O-8 of sialic acid in GM3 to form GD3 (NeuAc alpha 2-8NeuAc alpha 2 - 3Gal beta 1 - 4Glc - Cer). Substrate inhibition studies indicated that these two reactions are probably catalyzed by the same enzyme, SAT-2. The kinetic parameters of SAT-2 activity were determined. The Km values were 70 and 63 microM with CMP-[14C]NeuAc and LM1, respectively, when the detergent-solubilized supernatant fraction was used as enzyme source. The (alpha 2-8)-linkage between the terminal and penultimate sialic acids was determined using nonradioactive CMP-NeuAc and [Ac-14C]LM1 as substrates (Higashi, H., and Basu, S. (1982) Anal. Biochem. 120, 159-164) for the enzyme, followed by identification of the permethylated [14C]sialic acid of the product by radioautography. At 0.5 mM N-ethylmaleimide, the SAT-2 activity was inhibited 50% whereas SAT-1 and SAT-3 activities (Basu, M., Basu, S., Stoffyn, A., and Stoffyn, P. (1982) J. Biol. Chem. 257, 12765-12769) remained uninhibited.

Age Factors↗
PubMed1985

Nucleotide sequence of a major class-III phage-T3 RNA-polymerase promoter located at 98.0% of phage-T3 genetic map.

The entire nucleotide sequence of a 409-bp HincII fragment, located within the MboI-E fragment on bacteriophage T3 DNA and containing a major class-III T3 RNA polymerase promoter positioned at 98% on the standard T3 genetic map, has been determined. Alignment of this class-III promoter with previously determined T3 RNA polymerase promoters, with start points of transcription (+1) in register, indicates high degree of sequence conservation between position -16 to +6 among all T3 RNA polymerase promoters. The conserved portion of the (-) strand sequence is 5'-A-TA-T-AT-A-C-C-C-T-C-A-C-T-A-A-A-G-G-G-A---3'. This fragment also contains an open reading frame (ORF) with a translational start codon located at position +146 which is preceded by a potential ribosome binding site (RBS). There is more than 70% amino acid-sequence homology between the deduced sequences of the -NH2 terminal region of this putative T3 phage protein and the corresponding protein coded by bacteriophage T7 (protein of T7 gene 19.5).

Base Sequence↗
PubMed1985

Pygopagus twins.

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Adult↗
PubMed1985

Segmentation of wet elongated mitochondria into spheres.

Wet replication studies of potato mitochondria suggest that these mitochondria are basically elongated organelles of length 3-6 micron and width 0.5-0.9 micron. However due to unnatural extracellular and environmental conditions these mitochondria are subject to spontaneous segmentation or fission to yield organelles of smaller forms, and finally to round mitochondria, the diameter of which equals the width of the segmenting mitochondria. Only these reduced, round mitochondria are found as spherical mitochondria by the critical-point drying technique. Whereas this segmentation behavior of mitochondria points out the need for further improvement of the wet replication technique, it poses a serious issue: perhaps the real, undisputed shape and size of mitochondria remain to be determined.

Histological Techniques↗
PubMed1985

Cathodoluminescence studies: from chromatin and chromosome to human hair.

Evidence has been presented to prove that cathodoluminescence (CL) studies of chromosomes and spread, Giemsa stained chromatin may lead to early detection of structural changes, such as the superstructure of heterochromatin. Several compounds including the potent hallucinogenic drugs, LSD and cocaine, have been discovered to be cathodoluminescent. The main issue confronting the CL applications using biological stains is the need for a clear identification of the source (dye or drug) of CL contrast. Unequivocal proof to this matter has been given by studies in which the time-dependent incorporation of LSD into the non-cathodoluminescent, virtually impermeable human hairs have been presented. The major implication of this finding is in forensic applications.

Chromatin↗
PubMed1984

A rapid preparative method for isolation of neutral and acidic glycosphingolipids by radial thin-layer chromatography.

An efficient method to separate neutral and acidic glycosphingolipids (GSLs) from their mixtures within a short period (45-60 min) and with low consumption of solvents (chloroform-methanol-water, 60/35/8 (v/v/v); 250-500 ml) has been developed. This method utilizes a centrifugal thin-layer chromatograph (Chromatotron) and the GSL mixtures (30-400 mg) are applied to glass plates coated with a 1-mm layer of silica gel 60 PF-254. The method (radial thin-layer chromatography) is rapid and simple and the recovery of glycosphingolipids is high (70-80%).

Animals↗
PubMed1984

Biosynthesis in vitro of Ii core glycosphingolipids from neolactotetraosylceramide by beta 1-3- and beta 1-6-N-acetylglucosaminyltransferases from mouse T-lymphoma.

The N-acetylglucosaminyltransferases probably involved in the biosynthesis in vitro of Ii core glycosphingolipids have been solubilized from a membrane preparation of mouse lymphoma P-1798 and partially characterized. The detergent-extracted membrane supernatant contains both beta 1-3- and beta 1-6-N-acetylglucosaminyltransferase activities that transfer [3H]GlcNAc from UDP-[3H]GlcNAc to the terminal galactose of neolactotetraosylceramide (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-ceramide; nLcOse4ceramide), to form the Ii core structures. The linkage of [3H]N-acetylglucosamine incorporated into the terminal galactose of nLcOse4Cer was determined from identification of 2,4,6-tri-O-methyl[3H]galactose and 2,3,4-tri-O-methyl[3H]galactose after hydrolysis of the permethylated enzymatic products, GlcNAc beta-[3H]Gal-GlcNAc-Gal-Glc-ceramide. In addition to the presence of beta-N-acetylglucosaminyltransferases, we have detected a galactosyltransferase activity in this soluble supernatant fraction that catalyzes the transfer of [14C]galactose from UDP-[14C]galactose to lactotriaosylceramide (GlcNAc beta 1-3Gal beta 1-4Glc-ceramide; LcOse3ceramide) to form nLcOse4ceramide, the acceptor in the N-acetylglucosaminyltransferase-catalyzed reaction.

Animals↗