Isolates of Theileria annulata collected from different parts of India show phenotypic and genetic diversity.

Phenotypic and genetic polymorphism was studied amongst four Theileria annulata isolates collected from three different parts of India. Amongst various markers studied for the comparison of growth characteristics of schizont cell lines established from these isolates, viability, non-viability counts and nitric oxide (NO) production showed significant variation. A negative correlation was observed between NO production and mRNA expression for TNF-alpha, a potent proinflammatory cytokine related to the pathogenesis of the disease. Phenotypic polymorphism was also revealed by T. annulata schizont-specific monoclonal antibodies (Mabs), viz. 1C7, 1E11, 2G2 and EU-106, which recognized variable number of cells in indirect fluorescent antibody and indirect immunoperoxidase tests, when tested against the four T. annulata isolates collected from India. Genetic polymorphism was recognized amongst the four isolates by restriction digestion analysis of Tams-1 gene PCR products. These observations revealed that the four isolates of T. annulata are different from each other and might be expressing different antigenic determinants on their cell surface.

Underexpression of ap from R-plasmids in fast-growing Rhizobium species.

The presence of the plasmid RP1 in the cells of Rhizobium leguminosarum strains Rld1, 300, and 248, R. phaseoli 1233, R. trifolii strains T1 and 6661, and R. meliloti 4013 was found to appreciably increase bacterial resistance toward kanamycin and tetracycline but not toward ampicillin. The presence of 16 other R-plasmids in R. leguminosarum was also found to either not increase or only marginally increase bacterial resistance toward ampicillin. It appears now that underexpression of the plasmid-specified ampicillin function is common to most fast- and slow-growing rhizobia.