• Dwijen Sarkar

      Articles written in Journal of Biosciences

    • Expression of antigens in virulent and avirulent Indian strains ofLeishmania donovani

      Tapati Sanyal Prosenjit Gangopadhyay Dilip K Ghost Dwijen Sarkar

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      Indo-Gen mediated surface labelling with125I demonstrated differences in surface oriented antigens between virulent and virulent promastigote ofLeishniania donovani, In case of virulent strains, surface polypeptides with molecular masses of 63, 53, 42 and 38 kDa were found to be labelled with125I whereas in the case of aviralent stains 68, 55, 50, 46, 42 and 33 Da, components were iodinated. Further studies by immunoblot assay using different subcellular fractions of virulent and avirulent parasites demonstrated that antibody raised against gp63 cross-reacted with the 63 and 60 kDa antigen of the virulent and avirulentLeishmania donovani strains of Indian origin respectively. It indicates that these two polypeptides are antigenically similar. When virulent and avirulent cells were grown in the presence of varying concentration of tunicarnycin and immunoblot with anti gp63, it was observed that with increasing concentration of tunicamycin the 63 kDa polypeptide of the virulent cells shifted to approximately 58–57 kDa and the 60 kDa polypoptide of the aviruleni cells shifted to 57 kDa. This suggests that glycosylation may play an important role in antigenic variation between virulent and avirulent parasites.

    • Involvement ofLeishmania donovani major surface glycoprotein gp63 in promastigote multiplication

      Sanjeev Pandey Phuljhuri Chakraborti Rakhi Sharma Santu Bandyopadhyay Dwijen Sarkar Samit Adhya

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      The major surface glycoprotein gp63 of the kinetoplastid protozoal parasiteLeishmania is implicated as a ligand mediating uptake of the parasite into, and survival within, the host macrophage. By expressing gp63 antisense RNA from an episomal vector inL. donovani promastigotes, gp63-deficient transfectants were obtained. Reduction of the gp63 level resulted in increased generation times, altered cell morphology, accumulation of cells in the G2/M phase of the cell cycle, and increased numbers of binucleate cells with one or two kinetoplasts. Growth was stimulated, and the number of binucleate cells reduced, by addition to the culture of a bacterially expressed fusion protein containing the fibronectin-like SRYD motif and the zinc-binding (metalloprotease) domain of gp63. These observations support an additional role of gp63 in promastigote multiplication; the fibronectin-like properties of gp63 may be important in this process

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