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Biomedical subjects

R K Datta

Publications and source records attributed to R K Datta.

At least 19 recordsLinked to original sources
PubMed2002

Tropic failure of Phyllactinia corylea contributes to the mildew resistance of mulberry genotypes.

Different mulberry genotypes show great variation in their resistance to the powdery mildew Phyllactinia corylea. Conidial germination and hyphal growth of P. corylea on the leaf surface of two susceptible mulberry genotypes, viz., Kanva 2 (K2) and Victory 1 (V1) varieties of Morus indica, and on two resistant species, viz,, M. laevigata and M. serrata were studied by scanning electron microscopy. Conidial germination and growth of germ tubes were normal on all the leaves. The hyphae of P. corylea identify stomata on host leaves by their topographical features to produce the stomatopodia precisely over them. The holes and/or the grooves of stomata appear to provide the signals for the initiation of stomatopodia and similar structures are erratically developed over many local depressions or grooves on leaf surface. The abaxial surface of K2 leaf is smooth without prominent undulations of epidermal cell surface, and the stomata are flush with the leaf surface. Although successful penetration is also achieved on V1 leaf, its slightly undulated surface occasionally provides inaccurate tropic signals to the hyphae, inducing the development of stomatopodia away from the stomata. The leaf surfaces of M. laevigata and M. serrata are very rough with highly sculptured cuticle and abundant epidermal outgrowths. Stomata mostly remain sunken or hidden amidst the cuticular ornamentations and the hyphae fail to recognise the precise signals from them. As the surface architecture of the leaves provides many immense sources of tropic signals, stomatopodia are often produced over local depressions or grooves. In these cases the fungus fails to penetrate the leaf, does not develop beyond 24 h and penetration is rarely achieved on the leaves of the resistant plants. The study indicates that the stimulatory effect of the leaf surface topography of resistant varieties misleads the pathogen from successful penetration, thus contributing to the plant's resistance.

Ascomycota↗
PubMed1997

Production of monoclonal antibodies against Nosema bombycis and their utility for detection of pebrine infection in Bombyx mori L.

Latex agglutination assay based on monoclonal antibodies (MCAs) described in this communication may be useful for detection of Pebrine infection in silkworm. Four murine MCAs were produced against Nosema bombycis spore. In ELISA all 4 MCAs (IgM isotype) reacted with alkali treated Nosema spores and to variable extent with acetone precipitated surface protein. However, MA-310 and MA-542 showed a low degree of cross reactivity with BmNPV. In contrast, MA-503 and MA-515 were devoid of reactivity with BmNPV, B. thuringiensis, S. marcescens, Azotobactor, Rhizobium and normal hemolymph protein in ELISA. Latex beads sensitized with a combination of MA-503 and MA-515 (50 micrograms each per ml of 0.4% latex beads) could detect 1 x 10(5) Nosema spores per test. Sensitization of the latex beads with the cocktail of these two MCAs through protein-A bridge further led to a 10-fold increase in the sensitivity (1 x 10(4) spores/test) of the assay. No agglutination was observed in presence of BmNPV, Rhizobium, Azotobactor, E. coli, B. thuringiensis, S. marcescens and normal hemolymph protein indicating the specificity of the test. The results obtained by latex agglutination assay on hemolymph samples of infected as well as normal larvae collected from field, II instar larvae infected in the laboratory and from infected mother moth revealed 100% correlation with results by microscopic examination.

Animals↗
PubMed1997

Protein A linked latex antisera test for detection of infectious flacherie of silkworm, Bombyx mori L. caused by B. mori infectious flacherie virus.

Protein A linked latex antisera (PALLAS) test was used for detection of B. mori infectious flacherie virus (BmIFV) in silkworms. The test was found superior to direct latex agglutination (DLA) test for detection of BmIFV in infected larval and faecal matter extracts and purified preparations. Latex beads sensitized with anti-BmIFV IgG were able to detect up to 75 ng/ml BmIFV in PALLAS test and 300 ng/ml in DLA test. BmIFV was detected in diluted extracts of infected larvae (up to 1:200) and their faecal matter (up to 1:500). BmIFV progressive infection was detected at 12 and 24 hr of post infection in PALLAS and DLA tests, respectively in both larval and faecal matter extracts. PALLAS tests provides a simple, specific and highly sensitive test for detection of infectious flacherie virus.

Animals↗
PubMed1995

Purification and partial characterization of an induced antibacterial protein in the silkworm, Bombyx mori.

Injection of live Escherichia coli into larvae of the silkworm, Bombyx mori, induces antibacterial activity in the hemolymph. The major induced antibacterial activity was purified in two steps by CM-Sephadex C-50 and Sephadex G-100 column chromatography. After trypsin treatment, the purified antibacterial protein lost its activity and the antibacterial activity was found to be partially heat labile. The purified protein was a single polypeptide chain of molecular weight 16 kDa. The 20 N-terminal amino acid sequence of the protein was determined and this sequence showed homology with the N-terminal amino acid sequence of lysozymes reported in other species. The purified protein was found to have comparable antibacterial activity against both E. coli and Micrococcus luteus. The purification of antibacterial protein and the antibacterial properties of the purified protein are discussed.

Amino Acid Sequence↗
PubMed1995

Evaluation of protein-A linked monoclonal antibody latex agglutination test for diagnosis of nuclear polyhedrosis virus (BmNPV) of silkworm Bombyx mori L.

The symptomology of BmNPV infection in Bombyx mori L depends on the stages of infection. Discernible symptoms develop at later stages of infection, which leads to improper diagnosis and poor crop yield with sericulturists. In the present study development of direct and protein-A linked monoclonal antibody latex (PALMAL) agglutination test for the detection of BmNPV infection in silkworm is described. Latex beads were precoated with protein-A and then sensitised with monoclonal antibody MA-231 (125 micrograms/ml). PALMAL test could detect 1 x 10(5) nuclear polyhedra/test and is ten times more sensitive than the direct agglutination test employing purified polyclonal antibodies. No agglutination was observed in presence of B. thuringiensis, S. marcescens, N. bombycis, group-A streptococci, Staphylococcus aureus, E. coli and normal haemolymph protein indicating the specificity of the test. Fifty haemolymph samples collected from the field were evaluated by PALMAL test. Twenty one samples having infection other than BmNPV, failed to show positive agglutination. Twenty five samples having > or = 5 x 10(6) BmNPV/ml showed positive agglutination. However, 4 samples having < 5 x 10(6) BmNPV/ml failed to show positive agglutination thereby indicating the limit of sensitivity of the assay.

Animals↗
PubMed1991

Evaluation of three manually operated weeding devices.

Performance of three manually operated weeders was evaluated from ergonomics and mechanical considerations. Three operators were selected for laboratory and field trials; they represented the 5th, 50th and 95th percentiles of the operator population. Laboratory tests were conducted in a psychometric chamber to study physiological response under varying load and environmental conditions. From the data, relationships between energy expenditure rate and oxygen consumption rate vs heart rate were established. Field tests were carried out with the three weeders in a farm with Arhar crop (Cajannus Cajan L.) during August-September, when the average ambient temperature and relative humidity were 36 degrees C and 82% respectively. The results of this investigation indicated that weeding with the indigenous tools of a 'khurpi' and a spade and with the improved tool (3-tine hoe) could be rated as 'moderately heavy' work. However, a 'khurpi' demanded less energy expenditure than a 3-tine hoe followed by a spade. The squatting posture with a 'khurpi' appeared to be more comfortable than the standing posture with about 145 degrees erect position for the 3-tine hoe, followed by the standing posture with about 108 degrees erect position with the spade. For consideration of higher output, the order was spade, 3-tine hoe and 'khurpi', For weeding efficiency the trend was, however, just the reverse.

Journal Article↗
PubMed1983

Non specific aortoarteritis (Takayasu's disease). An immunologic and autopsy study.

Large segments of the aorta and its major branches were found to be diseased in 14 autopsied cases of aortoarteritis. Both renal arteries and the left subclavian artery were frequently affected. Superior vena cava thrombosis and thickening of the inferior vena cava were noted in one case each. Tuberculosis was present as small foci in only 3 of the 14 cases. Angiographic evaluation also revealed thickening and narrowing of diseased segments. The descending thoracic and abdominal aorta and renal arteries were frequently involved. Aneurysmal lesions were infrequent. Antiaorta antibodies were investigated using 4 different parameters. None of our cases showed their presence. The role of tuberculosis and/or autoimmunity appears unlikely in the etiopathogenesis of aortitis.

Adolescent↗
PubMed1978

Induction of dominant lethals with ethyl methane-sulfonate in male germ cells of mulberry silkwork, Bombyx mori l.

Sensitivity of male germ cells in the mulberry silkworm, Bombyx mori L., to ethyl methanesulfonate (EMS) was determined by treating newly emerged 5th- instar larvae, and 2-day- and 7-day-old pupae with 3 concentrations, 0.05, 0.1 and 0.15%, of the mutagen. The frequency of dominant-lethal mutations induced by EMS treatment was used as the parameter for the study. Spermatids and spermatozoa were markedly sensitive to EMS. Statistical analysis confirmed that differences in respect of percentage of egg hatch among the 3 different treatments as well as the interactions between the 3 factors, e.g. stages, hatchability and EMS treatment, were highly significant.

Animals↗
PubMed1977

Mescaline-induced changes of brain-cortex ribosomes. Mescaline demethylase activity of brain-cortex soluble supernatant.

Brain-cortex slices demethylate mescaline and p-methoxyacetanilide, a reference O-demethylating substrate, though the rate of demethylation of mescaline is about one third that of the reference substrate. The demethylase activity is localized mostly in the soluble supernatant (105 000 x g). It is purified 47-fold with respect to the demethylation of mescaline by ammonium sulfate precipitation and DEAE cellulose chromatography. The partially purified demethylase, which is stable for 3-5 days at -5 degrees C in the presence of dithiothreitol and glutathione and is inhibited by p-chloromercuribenzoate, has maximal activity at pH between 7.2 and 8.0. It demethylates mescaline into 3,4-dimethoxy-5-hydroxyphenethylamine and 3,5-dimethoxy-4-hydroxyphenethylamine and some unidentified derivatives.

Acetamides↗
PubMed1977

Binding of mescaline with subcellular fractions upon incubation of brain cortex slices with [14C] mescaline.

Incubation of brain cortex slices in the presence of glucose resulted in the permeation of about 65% of [14C] mescaline into slices. Of this, about one-third radioactivity was bound with nuclei, mitochondria, microsomes, and ribosomes. Dialysis of subcellular fractions did not markedly reduce the amounts of radioactivity bound to the fractions. The permeation into slices and the binding of mescaline to subcellular fractions were fairly time-dependent, but were inhibited by the presence of potassium cyanide, or by the absence of glucose and by heating to 80 degrees C for 1 min.

Animals↗
PubMed1976

Influence of acute and chronic administration of methadone hydrochloride on NADPH-cytochrome c reductase and cytochrome P-450 of mouse liver microsomes.

Administration of a single acute dose (20 mg/kg body weight) of methadone hydrochloride to both male and female mice increased the specific activity of NADPH-cytochrome c reductase and did not change much the content of cytochrome P-450 of their liver microsomes. Administration of multiple acute doses of methadone in male mice increased the specific activity of cytochrome c reductase and the content of cytochrome P-450 of their liver microsomes. Chronic administration of progressively increasing doses of methadone (up to 40 mg/kg body weight) to male mice increased the specific activity of c reductase. Similar chronic administration of methadone up to 28 mg/kg body weight also increased the microsomal content of P-450, but with higher doses of methadone, the content of P-450 declined and finally dropped slightly below control levels. The levels of c reductase activity and P-450 content returned to normal about two weeks after discontinuation of methadone administration.

Animals↗
PubMed1976

Effects of morphine sulfate on NADPH-cytochrome c reductase and cytochrome P-450 of mouse liver microsomes.

Three hr after i.p. administration of a single dose of 30 mg/kg of morphine to male mice, an increase in specific activity of NADPH-cytochrome c reductase by about 10% and the content of cytochrome P-450 by about 14% of their liver microsomes was observed.Administration of 30 mg/kg of morphine, once daily,during 5 days, caused about 16% and 9% increases in specific activity of c reductase and the content of P-450 respectively. Administration of a single dose of morphine to male and female mice caused no sex-dependent differences in the specific activity of c reductase and the content of P-450. Repeated administration of morphine up to 100 mg/kg to male mice increased the specific activity of microsomal c reductase by about 70%. Repeated administration of morphine up to 55 mg/kg also increased the microsomal content of P-450 by about 22%, but with higher doses of morphine, the content of P-450 declined and finally dropped below control levels. The levels of c-reductase activity and P-450 content returned to normal levels about 2 weeks after termination of morphine administration.

Animals↗