Naturally occurring plasmodium-specific IgA antibody in humans from a malaria endemic area

Blood samples collected from individuals belonging to an endemic area in Uttar Pradesh, were tested for plasmodial antigen specific immunoglobulin A (IgA) by enzyme immuno assay using soluble extract ofPlasmodium falciparum from culture. Among 773 (20.18%,P < 0.0001) samples 156 sera demonstrated a detectable seropositivity for antigen specific IgA. IgA levels were higher among individuals who experienced repeated attacks of malaria compared to acute infected patients. Among seropositive individuals the IgA titers were found increased with the age. Immunoglobulin isolated from sera having high level of IgA showed growth inhibitory effect inPlasmodium falciparum in vitro. A group of sera with high IgA antibody againstPlasmodium falciparum crude antigen showed seronegativity with specific peptides. Statistically, no positive or negative correlations were observed between antigen specific IgG and IgA. However, there was a tendency towards negative correlation between IgA and IgM. Mechanisms for the parasite specific IgA production remain to be established.     

Clustering and analysis of protein families.

Various sequence-motif and sequence-cluster databases have been integrated into a new resource known as InterPro. Because the contributing databases have different clustering principles and scoring sensitivities, the combined assignments complement each other for grouping protein families and delineating domains. InterPro and new developments in the analysis of both the phylogenetic profiles of protein families and domain fusion events improve the prediction of specific functions for numerous proteins.     

Adrenal dehydrogenases in alloxan diabetic rats following continuous exposure to light

The enzymes delta5-3beta-hydroxysteroid dehydrogenase delta5-3beta-HSD) and glucose-6-phosphate dehydrogenase (G-6-PDH) were demonstrated histochemically in the adrenal cortex of female rat. The activities of these enzymes were increased significantly in the alloxan-treated rats kept in LD (light: darkness) cycles of 10:14 h. Continuous light exposure to diabetic animals appeared to decrease delta5-3beta-HSD and g-6-PDH in comparison to the diabetic rats kept in 10 h illumination. The evidence indicates that suppression of adrenal steroidogenesis in diabetic rats after exposure to continuous light is due to the alteration of pentose phosphate pathway.     

Thermal,Chemical and pH Induced Unfolding of Turmeric Root Lectin: Modes of Denaturation

Curcuma longa rhizome lectin, of non-seed origin having antifungal, antibacterial and α-glucosidase inhibitory activities, forms a homodimer with high thermal stability as well as acid tolerance. Size exclusion chromatography and dynamic light scattering show it to be a dimer at pH 7, but it converts to a monomer near pH 2. Circular dichroism spectra and fluorescence emission maxima are virtually indistinguishable from pH 7 to 2, indicating secondary and tertiary structures remain the same in dimer and monomer within experimental error. The tryptophan environment as probed by acrylamide quenching data yielded very similar data at pH 2 and pH 7, implying very similar folding for monomer and dimer. Differential scanning calorimetry shows a transition at 350.3 K for dimer and at 327.0 K for monomer. Thermal unfolding and chemical unfolding induced by guanidinium chloride for dimer are both reversible and can be described by two-state models. The temperatures and the denaturant concentrations at which one-half of the protein molecules are unfolded, are protein concentration-dependent for dimer but protein concentration-independent for monomer. The free energy of unfolding at 298 K was found to be 5.23 Kcal mol⁻¹ and 14.90 Kcal mol⁻¹ for the monomer and dimer respectively. The value of change in excess heat capacity upon protein denaturation (ΔC_p) is 3.42 Kcal mol⁻¹ K⁻¹ for dimer. The small ΔC_p for unfolding of CLA reflects a buried hydrophobic core in the folded dimeric protein. These unfolding experiments, temperature dependent circular dichroism and dynamic light scattering for the dimer at pH 7 indicate its higher stability than for the monomer at pH 2. This difference in stability of dimeric and monomeric forms highlights the contribution of inter-subunit interactions in the former.     

Analysis of DevR regulated genes in Mycobacterium tuberculosis

The DevRS two component system of Mycobacterium tuberculosis is responsible for its dormancy in host and becomes operative under hypoxic condition. It is experimentally known that phosphorylated DevR controls the expression of several downstream genes in a complex manner. In the present work we propose a theoretical model to show role of binding sites in DevR mediated gene expression. Individual and collective role of binding sites in regulating DevR mediated gene expression has been shown via modeling. Objective of the present work is twofold. First, to describe qualitatively the temporal dynamics of wild type genes and their known mutants. Based on these results we propose that DevR controlled gene expression follows a specific pattern which is efficient in describing other DevR mediated gene expression. Second, to analyze behavior of the system from information theoretical point of view. Using the tools of information theory we have calculated molecular efficiency of the system and have shown that it is close to the maximum limit of isothermal efficiency.