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Biomedical subjects

D N Deobagkar

Publications and source records attributed to D N Deobagkar.

17 recordsLinked to original sources
PubMed2003

Enhanced esterase activity in salivary gland and midgut of Aedes aegypti mosquito infected with dengue-2 virus.

Mosquitoes were infected by intrathoracic inoculation. About 95% head squashes were positive for dengue virus antigen on the 15th post infection day (PID). Esterase activity was determined in the homogenates prepared from the salivary glands and midguts on different PIDs of dengue virus inoculated and control mosquitoes showed that it was consistently higher in the virus-infected batches.

Aedes↗
PubMed2001

Highly-substrate active isoenzyme acetylcholinesterase-II, in rosy eye mutant of Aedes aegypti mosquito.

Insecticide bioassays were carried out on larvae and adults of rosy eye mutant and wildtype strains of A. aegypti. Both the strains were equally susceptible to DDT, malathion and deltamethrin. Biochemical assays showed an increase in acetylcholinesterase enzyme (AChE) activity in all the stages of mutant strain with both the substrates i.e. acetylthiocholine iodide and S-butyrylthiocholine iodide. However, there was no difference in the percent inhibition of enzyme activity with propoxur in these two strains. Polyacrylamide gel electrophoresis performed in native conditions on the homogenates of adults of rosy eye mosquitoes showed that AChE-II allele was highly active with the substrate acetylthiocholine iodide as compared to wildtype strain. Frequency of the highly active AChE-II allele in the mutant strain was about 68%, whereas it was about 5% in the wildtype strain.

Acetylcholinesterase↗
PubMed1997

Characterization of cloned endoxylanase from Cellulomonas sp. NCIM 2353 expressed in Escherichia coli.

A 22-kDa xylanase encoded by a cloned gene (XCs16)of Cellulomonas was purified to homogeneity with an overall yield of 44%. It is a basic protein with a pI of 8.1 and has a Km and Vmax of 3 mg/ml and 1150 micromoles/mg/min, respectively, for oat spelt xylan at 55 degrees C and pH 5.8. Homologous xylanase from Cellulomonas could be identified with antibodies raised against purified xylanase encoded by XCs16. The enzyme from Cellulomonas also exhibited identical temperature and pH optimum and had a molecular weight of 23 kDa. Modification of tryptophan residue of purified xylanase resulted in the loss of xylanase activity. This loss could be reversed by the addition of substrate, indicating the involvement of tryptophan residue in the catalytic site.

Actinomycetales↗
PubMed1997

The glucanases of Cellulomonas.

Cellulomonas is a unique bacterium possessing not only the capacity to degrade various carbohydrates, such as starch, xylan and cellulose, but crystalline cellulose as well. It has developed a complex battery of glucanases to deal with substrates possessing such extensive microheterogeneities. Some of these enzymes are multifunctional, as well as cross inducible, possessing a multi-domain structure; these enzymes are thought to have arisen by the shuffling of these domains. Intergeneric hybrids have been constructed between Cellulomonas and Zymomonas so as to enhance the industrial potential of this organism. This review examines the unique features of this microorganism and evaluates its key role in the conversion of complex wastes to useful products, by virtue of its unusual attributes.

Journal Article↗
PubMed1996

Multifactional glucanases.

Diverse functional roles of multifunctional proteins arise from either their independent functional domains or dual activities mediated through a single active site. Presence of multifunctional proteins significantly enhances the metabolic efficiency of a cell. Microorganisms utilising complex substrates with extensive microheterogeneities, such as carbohydrates evolved batteries of multifunctional glucanases, facilitating parsimonious utilisation of these substrates. Various attempts have since been made to artificially construct these glucanases. Analysis of information on various glucanases would be helpful in understanding the evolutionary interrelationship between this class of enzymes and will give an insight into the structural features controlling different unrelated activities. This review examines the genesis, evolution and structural features of multifunctional glucanases.

Journal Article↗
PubMed1996

Adaptive larval thermotolerance and induced cross-tolerance to propoxur insecticide in mosquitoes Anopheles stephensi and Aedes aegypti.

Fourth-instar larvae of mosquitoes Anopheles stephensi and Aedes aegypti normally died within 90 min at 43 degrees C. Pre-exposure to high but sublethal temperatures conferred adaptive thermotolerance, dependent on the temperature and the duration of pre-exposure. Adaptive cross-tolerance to propoxur (a carbamate insecticide) was also induced in larvae by pre-exposing them to sublethal temperatures. Pre-exposure to sublethal concentrations of propoxur was found to confer cross-thermotolerance to a lower extent. These results suggest that the shock proteins (e.g. heat shock proteins) induced by unrelated stress factors play an important role in the development of adaptive cross-protection (stress response) to other stress conditions.

Aedes↗
PubMed1993

Protoplast fusion: a tool for intergeneric gene transfer in bacteria.

Protoplasts can be isolated from bacterial cells by digestion of the cell wall with the help of lysozyme in presence of osmotic stabilizers. Fusion of protoplasts can be induced by chemical fusogens like polyethylene glycol. The electrofusion technique has been reported in bacteria in which the fusion frequency is much higher than that obtained by PEG induced protoplast fusion. This technology allows recombination to take place not only between related species but also between unrelated genera and is of great potential in the breeding and improvement of industrial strains. This review includes the information and developments on the protoplast fusion in bacteria with special reference to genetic recombination by protoplast fusion between phylogenetically unrelated bacteria.

Journal Article↗
PubMed1986

Partial purification and properties of the assimilatory nitrate reductase of the food yeast Candida utilis.

The addition of nitrate, EDTA and dithiothreitol to the enzyme extraction buffer resulted in improved stability of the assimilatory nitrate reductase activity from the food yeast Candida utilis at both 4 degrees C and -10 degrees C. By incorporating this critical step in the following sequence the yeast NAD(P)H: nitrate oxidoreductase (EC 1.6.6.2) was purified approximately 68-fold by protamine sulphate precipitation, calcium gel adsorption, ion exchange chromatography and gel filtration. Both NADPH-nitrate reductase and NADH-nitrate reductase activities remained in constant association and ratio (2:3) during the entire course of purification. The enzyme showed an absolute requirement of NADPH or NADH for its activity. Maximal enzyme activity was obtained with 10-120 micrograms protein in a 10 min assay at 30 degrees C at pH 6.5, with an apparent Michaelis constant of 0.69 mM for nitrate as substrate. The enzyme is a molybdoflavo-protein involving sulphydryl groups, and is highly sensitive to free reducing agents, heavy metal ions and electron-transfer inhibitors. The results also suggested possible involvement of a second metal ion, perhaps iron, which was hypothesized to participate in the electron transfer scheme catalysed by this enzyme.

Candida↗
PubMed1978

Cells nonproductively transformed by Abelson murine leukemia virus express a high molecular weight polyprotein containing structural and nonstructural components.

Cell clones nonproductively transformed by the replication-defective Abelson strain of murine leukemia virus (AbLV) were analyzed for type C viral antigen expression by competition immunoassay. AbLV-transformed mink non-producer lines were found to express a 110,000- to 130,000-molecular weight polyprotein containing murine leukemia virus gag proteins p15 and p12 covalently linked to nonstructural AbLV-coded component(s) of around 80,000-100,000 molecular weight. This polyprotein lacked detectable antigenic cross-reactivity with other virion-coded gag gene proteins such as p30, p10, the viral reverse transcriptase (RNA-dependent DNA polymerase), or the major viral envelope glycoprotein, gp70. By analogy to earlier data on feline and avian sarcoma viruses, these results suggest that a portion of this polyprotein might represent the AbLV src gene product and that in translation it is initially linked in precursor form to gag structural proteins. Superinfection of mink cells nonproductively transformed by AbLV--with either a wild mouse amphotropic type C virus isolate, 4070-A, or with the endogenous cat virus, RD114--led to production of pseudotype virus containing high concentrations of the AbLV-coded precursor polyprotein.

Antigens, Viral↗
PubMed1978

Murine leukemia virus (T-8)-transformed cells: identification of a precursor polyprotein containing gag gene-coded proteins (p15 and p12) and a nonstructural component.

Mink cells nonproductively transformed by the T-8 strain of mink cell focus-inducing virus express two type C viral amino terminal gag gene-coded structural proteins, p15 and p12, in the form of a 90,000 to 110,000 molecular weight polyprotein that lacks detectable immunological reactivity with other known type C virus-coded translational products. The observation concurs with the previous demonstration of similar high-molecular-weight precursor polyproteins in cell lines nonproductively transformed by either of two other mammalian sarcoma viruses also limited in virus-coded structural protein expression to p15 and p12.

Animals↗
PubMed1978

Studies on transfer RNA from mycobacteria.

Active preparations of tRNA and aminoacyl-tRNA synthetases have been isolated from exponentially growing cells of Mycobacterium smegmatis and Mycobacterium tuberculosis H37Rv. Though the aminoacyl-tRNA synthetases of older cells retain their activity, the tRNAs seem to undergo modification and show poorer activity. The mycobacterial enzyme preparations catalyse homologous and heterologous aminoacylation between tRNA from the two species (M. smegmatis and M. tuberculosis H37Rv) or from Escherichia coli, with equal efficiency; tRNA samples from eukaryotic cells (yeast and rat liver) do not serve as substrates for the mycobacterial synthetases. The analytical separation of the different amino acid specific tRNAs from M. smegmatis resembles the pattern found in other bacteria. Purification of valine- (three species) and methionine-specific tRNA (two species) to 70-80% purity has been accomplished by using column-chromatographic techniques. Of the two species of tRNAMet, one can be formylated in the presence of formyl tetrahydrofolate and the transformylase from mycobacteria.

Amino Acyl-tRNA Synthetases↗
PubMedDate not supplied

Characterization of MboI repeat DNA sequence of Anopheles stephensi.

MboI repeat fragment of mosquito Anopheles stephensi has been isolated by molecular cloning. The restriction map and entire nucleotide sequence of the 433bp insert has been determined. Hybridization of this repeat DNA with restriction enzyme digest of mosquito DNA does not show an interspersed pattern but suggests that this repeat may be tandemly repeated at one major site and a few minor sites in the genome of Anopheles stephensi. The hybridization pattern also indicates that this repeat family comprises of many similar but non-identical sequences. An open reading frame encoding 66 amino acids with an initiation and two tandem termination codons has been identified. This putative 66 amino acid polypeptide sequence has significant homology to a small region of RNA tumour viral envelope protein.

Animals↗