• Rajkumar S

      Articles written in Journal of Biosciences

    • Factors influencing offspring traits in the oviparous multi-clutched lizard,Calotes versicolor (Agamidae)

      Rajkumar S Radder Bhagyashri A Shanbhag

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      The determinants of offspring size and number in the tropical oviparous multi-clutched lizard,Calotes versicolor, were examined using both univariate and multivariate (path) analyses. InC. versicolor maternal snout-vent length (SVL) and body condition influence clutch mass and clutch size but have no significant influence on offspring size. The positive effect of maternal SVL and body condition on offspring number is counterbalanced by a negative effect of breeding time on egg mass. In fact, breeding time directly influences the offspring body mass and condition through variation in the egg mass. There is a trade-off between offspring mass and condition with offspring number, and breeding time influences both. Offspring hatched from the eggs of early (May–June) or mid (July–August) breeding periods invariably show lower mass and condition than those hatched from the eggs of late breeding season (September–October). Yet, there is no variation in offspring SVL among early, mid and late clutches. Thus, inC. versicolor offspring SVL is optimized while body mass and condition are not optimized.

    • Maternally derived egg yolk steroid hormones and sex determination: Review of a paradox in reptiles

      Rajkumar S Radder

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      During the past decade, maternally derived steroid hormones in the egg yolk of oviparous vertebrates have been the focus of attention for their possible role in sex determination and hence, information on the consequences of maternal egg yolk steroids on sex determination has accumulated rapidly in reptiles and birds. Until recently, the observations were dominated by the idea that yolk steroids of maternal origin play an important role in sex determination of oviparous vertebrates. However, more recent studies have cast significant doubt on the above conclusion. These studies suggest instead that steroids may be present in the yolk simply as the byproduct of passive uptake during yolk formation or observed correlations might reflect embryonically produced rather than maternally derived steroids. Thus, the objective of the present review is

      to provide an overview of such paradoxical observations on the role of maternal yolk steroids in sex determination of reptiles,

      to identify and provide brief explanations for the observed paradoxical results, and

      to provide some future research directions.

    • Cx43, ZO-1, alpha-catenin and beta-catenin in cataractous lens epithelial cells

      Anshul I Arora Kaid Johar Devarshi U Gajjar Darshini A Ganatra Forum B Kayastha Anuradha K Pal Alpesh R Patel Rajkumar S Abhay R Vasavada

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      Specimens of the anterior lens capsule with an attached monolayer of lens epithelial cells (LECs) were obtained from patients (𝑛=52) undergoing cataract surgery. Specimens were divided into three groups based on the type of cataract: nuclear cataract, cortical cataract and posterior subcapsular cataract (PSC). Clear lenses (𝑛=11) obtained from donor eyes were used as controls. Expression was studied by immunofluorescence, real-time PCR and Western blot. Statistical analysis was done using the student’s 𝑡-test. Immunofluorescence results showed punctate localization of Cx43 at the cell boundaries in controls, nuclear cataract and PSC groups. In the cortical cataract group, cytoplasmic pools of Cx43 without any localization at the cell boundaries were observed. Real-time PCR results showed significant up-regulation of Cx43 in nuclear and cortical cataract groups. Western blot results revealed significant increase in protein levels of Cx43 and significant decrease of ZO-1 in all three cataract groups. Protein levels of alpha-catenin were decreased significantly in nuclear and cortical cataract group. There was no significant change in expression of beta-catenin in the cataractous groups. Our findings suggest that ZO-1 and alpha-catenin are important for gap junctions containing Cx43 in the LECs. Alterations in cell junction proteins may play a role during formation of different types of cataract.

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