• A K Gupta

      Articles written in Journal of Biosciences

    • Preparation of standard amoeba-antigen from axenicEntamoeba histolytica and its use in the serodiagnosis and seroepidemiology of amoebiasis

      S R Das S A Kidwai A K Gupta

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      A method described for large scale cultivation ofEntamoeba histolytica axenically in a modified Diamond’s TP-S-1 monophasic medium. Crude amoebaantigen prepared by the ultrasonication of the trophozoites ofE. histolytica, was fractionated by sephadex G-200 column into four different fractions. The whole antigen and its different fractions were freeze-dried and upon reconstitution contained approximately 1.8 mg N/ml or roughly the equivalent of 10 × 106 amoebae per ml. Both whole antigen and its fractions have been used for the detection of specific antibody in the patients’ sera. Rabbits were immunised with the antigen and the immunoglobulins were separated from hyperimmune sera by DEAE-cellulose chromatography and salt fractionations. Sera collected from different categories of amoebiasis patients, amoebic liver abscess, amoebic hepatitis, amoebic dysentery, and asymptomatic amoebiasis, were tested serologically using standard amoeba-antigen for serodiagnosis and epidemiological assay of amoebiasis. Results of the assay showed that standard amoeba-antigen is very useful for diagnosis of invasive amoebiasis.

    • Deep-sea palaeoceanography of the Maldives Islands (ODP Hole 716A), equatorial Indian Ocean during MIS 12–6

      S Sarkar A K Gupta

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      Deep-sea benthic foraminifera, planktic foraminifer Globigerina bulloides and pteropods have been quantitatively analysed in 451 samples from Ocean Drilling Program (ODP) Hole 716A, to understand both surface and deep-sea palaeoceanographic changes in the equatorial Indian Ocean basin during the late Quaternary (∼444–151 Kyrs). Benthic foraminifera were analysed from > 125 𝜇m size fraction whereas Globigerina bulloides and pteropods were analysed from > 150 𝜇m size fraction. Factor analysis of most dominant benthic foraminiferal species over the studied time span made it possible to identify three biofacies characterizing distinct deep-sea environmental settings at Hole 716A. The environmental interpretation of each species is based on the ecology of recent deep-sea benthic foraminifera. The faunal record indicates fluctuating deep-sea conditions including changes in surface productivity, organic food supply and deep-sea oxygenation linked to changing wind intensities. These changes are pronounced on glacial-interglacial time scales driven by summer monsoon winds.

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