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Biomedical subjects

B N Chakraborty

Publications and source records attributed to B N Chakraborty.

9 recordsLinked to original sources
PubMed1997

Detection of cross-reactive antigens shared by Fusarium oxysporum and Glycine max by indirect ELISA and their cellular location in root tissues.

Pathogenicity test of Fusarium oxysporum on ten cultivars of soybean revealed Soymax and Punjab-1 to be most resistant while JS-2 and UPSM-19 were most susceptible. Antigens were prepared from the roots of all the ten varieties of soybean and the mycelium of F. oxysporum. Polyclonal antisera were raised against the mycelial suspension of F. oxysporum and the root antigen of the susceptible cultivar UPSM-19. Cross reactive antigens shared by the host and the pathogen were detected first by immunodiffusion. The immunoglobulin fraction of the antiserum was purified by ammonium sulfate precipitation and DEAE-Sephadex column chromatography. The immunoglobulin fractions were used for detection of cross-reactive antigens by enzyme-linked immunosorbent assay. In enzyme-linked immunosorbent assay, antigens of susceptible cultivars showed higher absorbance values when tested against the purified anti-F. oxysporum antiserum. Antiserum produced against UPSM-19 showed cross-reactivity with the antigens of other cultivars. Indirect staining of antibodies using fluorescein isothiocyanate indicated that in cross-sections of roots of susceptible cultivar (UPSM-19) cross-reactive antigens were concentrated around xylem elements, endodermis and epidermal cells, while in the resistant variety, fluorescence was concentrated mainly around epidermal cells and distributed in the cortical tissues. CRAs were also present in microconidia, macroconidia and chlamydospores of the fungus.

Antigens↗
PubMed1995

Sequence repeat-induced disruption of the major heat-inducible HSP70 gene of Neurospora crassa.

The process of repeat-induced point mutation (RIP) was used to disrupt hsps-1, the gene encoding the major heat-inducible member of the HSP70 family of Neurospora crassa. A plasmid DNA, containing an incomplete copy of hsps-1 and the selectable marker qa-2+, was introduced into germinated conidia. The sexual progeny of transformants with ectopically integrated hsps-1 DNA was examined for RIP by Southern-blot analysis of MboI- and Sau3A-digested genomic DNA. Progeny strains, showing RIP, were tested for heat shock-responsive expression of hsps-1, by RNA-blot hybridization and Western-blot analysis, as well as for thermotolerance. Isolates with RIP showed low levels of hsps-1 mRNA and a lack of induction of HSP70 protein by heat shock, accompanied by only a marginal decrease in the acquisition of thermotolerance.

Blotting, Northern↗
PubMed1994

Accumulation of antifungal compounds in tea leaf tissue infected with Bipolaris carbonum.

Varietal resistance of tea towards Bipolaris carbonum was tested following detached leaf inoculation technique. Among the fourteen varieties tested, three were found to be highly susceptible, while other three were resistant. Leaf exudates and diffusates collected from the resistant varieties were more fungitoxic than those from the susceptible ones. Two antifungal compounds isolated from healthy and B. carbonum-infected tea leaves exhibited clear inhibition zones at RF 0.8 and 0.65, respectively, in a chromatographic bioassay. On the basis of their color reaction on TLC and UV-spectra these were identified to be catechin and pyrocatechol. Resistant and susceptible varieties accumulated 439-510 and 187-212 micrograms/g fresh mass tissue of pyrocatechol, respectively, 2 d after inoculation with B. carbonum, while a low concentration (45-58 micrograms/g) of this compound was detected in healthy leaf tissue.

Antifungal Agents↗
PubMed1991

An electroporation-based system for high-efficiency transformation of germinated conidia of filamentous fungi.

A rapid and efficient electroporation procedure has been developed for transformation of germinating conidia of filamentous fungi. Pretreatment of conidial preparations with a cell wall weakening agent, such as beta-glucuronidase, was found to be essential for successful transformation. Using the qa-2+ gene of Neurospora crassa, encoding the catabolic dehydroquinase, as a selectable marker with a double-mutant host strain, auxotrophic for aromatic amino acids, integration of the plasmid was observed to be predominantly at ectopic chromosomal sites. Cotransformation with the qa-2+ gene and a plasmid containing a heat shock gene sequence (hsp70 of N. crassa) suggested integration site preference. High efficiencies of transformation to hygromycin resistance were achieved employing the bacterial hygromycin B phosphotransferase gene with N. crassa, the patulin-producer Penicillium urticae, and the causal agent of blackleg disease of crucifers, Leptosphaeria maculans. The economically important species Aspergillus oryzae was similarly transformed to benomyl resistance with the benomyl-resistant beta-tubulin gene of N. crassa as a dominant selectable marker.

Ascomycota↗
PubMedDate not supplied

Biochemical studies following ovulation induction with clomiphene citrate and human menopausal gonadotropin in infertile Indian women.

Biochemical studies were done in 65 anovulatory women before and following induction of ovulation with ethinyl estradiol/clomiphene citrate/human chorionic gonadotropin and also clomiphene citrate/human menopausal gonadotropin/human chorionic gonadotropin to determine the metabolic adverse effects, if any, of such therapy. Significant increases occurred in lipids and lipoprotein levels, while minor changes were seen in liver function enzymes and fasting blood sugar. Sialic acid decreased significantly after therapy in both the regimens, and both induction therapies seem to be free of adverse metabolic effects of hormones. On comparison with normal ovulatory women, this study suggests that some of the biochemical parameters can serve as reliable indicators of ensuing ovulation.

Adult↗