IL-10- and TGF-beta-mediated susceptibility in kala-azar and post-kala-azar dermal leishmaniasis: the significance of amphotericin B in the control of Leishmania donovani infection in India

Visceral leishmaniasis (VL) or kala-azar is known to be associated with a mixed Th1-Th2 response, and effective host defense requires the induction of IFN-gamma and IL-12. We address the role of the differential decline of IL-10 and TGF-beta in response to sodium antimony gluconate (SAG) and amphotericin B (AmB), the therapeutic success of SAG and AmB in Indian VL, and the significance of IL-10 and TGF-beta in the development and progression of post-kazla-azar dermal leishmaniasis (PKDL). In the active disease, PBMC from VL patients showed suppressed Ag-specific lymphoproliferation, IFN-gamma and IL-12 production, and elevation of IL-10 and TGF-beta. Cure corresponded with an elevation in IFN-gamma and IL-12 production and down-regulation of IL-10 and TGF-beta. Both CD4(+) and CD8(+) T cells were involved in IFN-gamma and IL-10 production. Interestingly, the retention and maintenance of residual IL-10 and TGF-beta in some SAG-treated individuals and the elevation of IL-10 and TGF-beta in PKDL, a sequel to kala-azar, probably reflects the role of these cytokines in reactivation of the disease in the form of PKDL. Contrastingly, AmB treatment of VL resulted in negligible TGF-beta levels and absolute elimination of IL-10, reflecting the better therapeutic activity of AmB and its probable role in the recent decline in PKDL occurrences in India. Moreover, elucidation of immune responses in Indian PKDL patients revealed a spectral pattern of disease progression where disease severity could be correlated inversely with lymphoproliferation and directly with TGF-beta, IL-10, and Ab production. In addition, the enhancement of CD4(+)CD25(+) T cells in active VL, their decline at cure, and reactivation in PKDL suggest their probable immunosuppressive role in these disease forms.     

Dissecting the non-specific and specific components of the initial folding reaction of barstar by multi-site FRET measurements

Initial polypeptide chain collapse plays a major role in the development of subsequent structure during protein folding, but it has been difficult to elucidate the coupling between its cooperativity and specificity. To better understand this important aspect of protein folding, nine different intramolecular distances in the protein have been measured by fluorescence resonance energy transfer (FRET) in the product(s) of the initial, sub-millisecond collapse reaction during the folding of barstar, under different folding conditions. All nine distances contract in these initial folding products, when the denaturant concentration is reduced. Two of these distances were also measured in peptides corresponding to sequence segments 38-55 and 51-69 of the protein. Surprisingly, both distances do not contract in the peptides which remain fully unfolded when the denaturant concentration is reduced. This suggests that the contraction of at least some segments of the polypeptide chain may be facilitated only by contraction of other segments. In the case of the initial product of folding of the protein, the dependence on denaturant concentration of the relative change in each distance suggests that there are two components to the initial folding reaction. One is a nonspecific component, which appears to be driven by the change in denaturant concentration that is used to initiate refolding. This component corresponds to the collapse of completely unfolded protein (U) to unfolded protein in refolding conditions (U(C)). The extent of nonspecific collapse can be predicted by the response of completely unfolded protein to a change in denaturant concentration. All distances undergo such solvent-induced contraction, but each distance contracts to a different extent. There is also a specific component to initial sub-millisecond folding, in which some distances (but not all) contract more than that predicted by solvent-induced contraction. The observation that only some of the distances undergo contraction over and above solvent-induced contraction, suggest that this specific component is associated with the formation of a specific intermediate (I(E)). FRET efficiency and distance change differently for the different donor-acceptor pairs, with a change in denaturant concentration, indicating that the formation or dissolution of structure in U(C) and I(E) does not happen in a synchronized manner across different regions of the protein molecule. Also, all nine FRET efficiencies and intramolecular distances in the product(s) of sub-ms folding, change continuously with a change in denaturant concentration. Hence, it appears that the transitions from U to U(C) and to I(E) are gradual transformations, and not all-or-none structural transitions. Nevertheless, the product of these gradual transitions, I(E), possesses specific structure.     

Activation of Candida rugosa lipase at alkane-aqueous interfaces: a molecular dynamics study

The effect of solvent hydrophobicity on activation of Candida rugosa lipase (CRL) was investigated by performing molecular dynamics simulations for four nano seconds (ns). The closed/inactive conformer of CRL (PDB code 1TRH) was solvated in three alkane-aqueous environments. The alkanes aggregated in a predominantly aqueous environment and by 1 ns a stable spherical alkane-aqueous interface had formed. This led to the interfacial activation of CRL. On analyzing the simulated conformers with the closed conformer of CRL, the flap was found to have opened from a closed state by 7.7 A, 10.2 A, 13.1 A at hexane-aqueous, octane-aqueous, and decane-aqueous interfaces. Further, essential dynamics analysis revealed that major anharmonic fluctuations were confined to residues 64-81, the flap of CRL.     

Production of lactic acid from cellobiose and cellotriose by Lactobacillus delbrueckii mutant Uc-3

Lactobacillus delbrueckii mutant Uc-3 utilizes both cellobiose and cellotriose efficiently, converting it into L(+) lactic acid. The enzyme activities of cellobiose and cellotriose utilization were determined for cell extracts, whole cells, and disrupted cells. Aryl-beta-glucosidase activity was detected only for whole cells and disrupted cells, suggesting that these activities are cell bound. The mutant produced 90 g/liter of lactic acid from 100 g/liter of cellobiose with 2.25 g/liter/h productivity.     

DIVERSITY IN GUT MICROFLORA OF Helicoverpa armigera POPULATIONS FROM DIFFERENT REGIONS IN RELATION TO BIOLOGICAL ACTIVITY OF Bacillus thuringiensis δ‐ENDOTOXIN Cry1Ac

Transgenic crops expressing toxin proteins from Bacillus thuringiensis (Bt) have been deployed on a large scale for management of Helicoverpa armigera. Resistance to Bt toxins has been documented in several papers, and therefore, we examined the role of midgut microflora of H. armigera in its susceptibility to Bt toxins. The susceptibility of H. armigera to Bt toxin Cry1Ac was assessed using Log‐dose‐Probit analysis, and the microbial communities were identified by 16S rRNA sequencing. The H. armigera populations from nine locations harbored diverse microbial communities, and had some unique bacteria, suggesting a wide geographical variation in microbial community in the midgut of the pod borer larvae. Phylotypes belonging to 32 genera were identified in the H. armigera midgut in field populations from nine locations. Bacteria belonging to Enterobacteriaceae (Order Bacillales) were present in all the populations, and these may be the common members of the H. armigera larval midgut microflora. Presence and/or absence of certain species were linked to H. armigera susceptibility to Bt toxins, but there were no clear trends across locations. Variation in susceptibility of F₁ neonates of H. armigera from different locations to the Bt toxin Cry1Ac was found to be 3.4‐fold. These findings support the idea that insect migut microflora may influence the biological activity of Bt toxins.     

Does CK2 affect flowering time by modulating the autonomous pathway in Arabidopsis?

CK2 (Casein kinase II), a ubiquitous Ser/Thr kinase, affects multiple developmental and stress response pathways in Arabidopsis, including flowering time under both long- and short-day conditions through the photoperiod and autonomous pathways. CK2 phosphorylates central clock components, CCA1 and LHY, to modulate circadian clock that regulates flowering time through the photoperiod pathway. However, how CK2 regulates flowering time through the autonomous pathway is still unknown. Analyses of phosphorylation sites using several prediction softwares show that most of the autonomous pathway components have multiple CK2 phosphorylation sites. CK2 might phosphorylate any or all of these components to modulate their activity/stability resulting in altered expression of FLC that drives flowering time through the autonomous pathway.     

The pathogenesis of atrial and atrioventricular septal defects with special emphasis on the role of the dorsal mesenchymal protrusion

Partitioning of the four-chambered heart requires the proper formation, interaction and fusion of several mesenchymal tissues derived from different precursor populations that together form the atrioventricular mesenchymal complex. This includes the major endocardial cushions and the mesenchymal cap of the septum primum, which are of endocardial origin, and the dorsal mesenchymal protrusion (DMP), which is derived from the Second Heart Field. Failure of these structures to develop and/or fully mature results in atrial septal defects (ASDs) and atrioventricular septal defects (AVSD). AVSDs are congenital malformations in which the atria are permitted to communicate due to defective septation between the inferior margin of the septum primum and the atrial surface of the common atrioventricular valve. The clinical presentation of AVSDs is variable and depends on both the size and/or type of defect; less severe defects may be asymptomatic while the most severe defect, if untreated, results in infantile heart failure. For many years, maldevelopment of the endocardial cushions was thought to be the sole etiology of AVSDs. More recent work, however, has demonstrated that perturbation of DMP development also results in AVSD. Here, we discuss in detail the formation of the DMP, its contribution to cardiac septation and describe the morphological features as well as potential etiologies of ASDs and AVSDs.     

Antioxidant activity of some polyphenol constituents of the medicinal plant Phyllanthus amarus Linn

Phyllanthus amarus Linn is a widely distributed tropical medicinal plant highly valued for its therapeutic properties. The antioxidant activity of some of its principal constituents, namely amariin, 1-galloyl-2,3-dehydrohexahydroxydiphenyl (DHHDP)-glucose, repandusinic acid, geraniin, corilagin, phyllanthusiin D, rutin and quercetin 3-O-glucoside were examined for their ability to scavenge free radicals in a range of systems including 2,2-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS)/ferrylmyoglobin, ferric reducing antioxidant power (FRAP) and pulse radiolysis. In addition, their ability to protect rat liver mitochondria against oxidative damage was determined by measuring the ROO* radical induced damage to proteins and lipids and *OH radical induced damage to plasmid DNA. The compounds showed significant antioxidant activities with differing efficacy depending on the assays employed. Amariin, repandusinic acid and phyllanthusiin D showed higher antioxidant activity among the ellagitannins and were comparable to the flavonoids, rutin and quercetin 3-O-glucoside.