Kulikovskiyia gen. nov. (Bacillariophyceae) from the lateritic rock pools of the Western Ghats,India and from Hainan Province,China

A new triundulate naviculoid diatom genus is described from the Western Ghats of Peninsular India and Hainan Province, China. The new taxon, Kulikovskiyia gen. nov. has robust conical spines along its margin and at the apices and the external valve face has longitudinally‐oriented siliceous slat system extending the length of the valve. The external distal raphe ends bifurcate and terminates on the valve face. There appear to be superficial similarities between this Asian genus and species and Playaensis, a genus comprised of two species found only in the western USA. The systematic position of Kulikovskiyia is discussed, and other than noting its similarities to other biraphid naviculoid diatoms due to symmetry features and the position of the raphe, we are uncertain about its systematic placement at finer levels of classification.     

A review on interplay between small RNAs and oxidative stress in cancer progression

Molecular and Cellular Biochemistry - Oxidative stress has been known to be the underlying cause in many instances of cancer development. The new aspect of cancer genesis that has caught the...     

Molecular recognition of a model globular protein apomyoglobin by synthetic receptor cyclodextrin: effect of fluorescence modification of the protein and cavity size of the receptor in the interaction

Labelling of proteins with some extrinsic probe is unavoidable in molecular biology research. Particularly, spectroscopic studies in the optical region require fluorescence modification of native proteins by attaching polycyclic aromatic fluoroprobe with the proteins under investigation. Our present study aims to address the consequence of the attachment of a fluoroprobe at the protein surface in the molecular recognition of the protein by selectively small model receptor. A spectroscopic study involving apomyoglobin (Apo‐Mb) and cyclodextrin (CyD) of various cavity sizes as model globular protein and synthetic receptors, respectively, using steady‐state and picosecond‐resolved techniques, is detailed here. A study involving Förster resonance energy transfer, between intrinsic amino acid tryptophan (donor) and N, N‐dimethyl naphthalene moiety of the extrinsic dansyl probes at the surface of Apo‐Mb, precisely monitor changes in donor acceptor distance as a consequence of interaction of the protein with CyD having different cavity sizes (β and γ variety). Molecular modelling studies on the interaction of tryptophan and dansyl probe with β‐CyD is reported here and found to be consistent with the experimental observations. In order to investigate structural aspects of the interacting protein, we have used circular dichroism spectroscopy. Temperature‐dependent circular dichroism studies explore the change in the secondary structure of Apo‐Mb in association with CyD, before and after fluorescence modification of the protein. Overall, the study well exemplifies approaches to protein recognition by CyD as a synthetic receptor and offers a cautionary note on the use of hydrophobic fluorescent labels for proteins in biochemical studies involving recognition of molecules. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of Lactobacillus rhamnosus NCDC 298 with FOS in Combination on Viability and Toxin Production of Enterotoxigenic Escherichia coli

Probiotics and Antimicrobial Proteins - The present study was to investigate the utilization of prebiotics by Lactobacillus rhamnosus NCDC 298 and its synergistic adversary effect on both...     

Light-controlled gene silencing in zebrafish embryos

Functional genomic studies in zebrafish frequently use synthetic oligonucleotides called morpholinos that block RNA splicing or translation. However, the constitutive activity of these reagents limits their experimental utility. We report here the synthesis of a photoactivatable morpholino targeting the no tail (ntl) gene. This caged reagent permits spatiotemporal gene regulation in vivo and the photochemical generation of functionally mosaic organisms.     

Solid state and solution conformations of a helical peptide with a central gly-gly segment

The influence of amino acids with contrasting conformational tendencies on the stereochemistry of oligopeptides has been investigated using an octapeptide Boc-Leu-Aib-Val-Gly-Gly-Leu-Aib-Val-OMe, which contains two helix-promoting Aib residues and a central helix-destabilizing Gly-Gly segment. Single crystal x-ray diffraction studies reveal that a 3 ₁₀-helix is formed up to the penultimate Aib residue, at which point there is a helix reversal in the backbone, reminiscent of a C-terminal 6 → I hydrogen bond. The curious feature in the crystal is the solvation of the possible 6 → 1 bond by a CH₃OH molecule, where the OH is inserted between O(3) and N(8) and participates in hydrogen bonds with both. The cell parameters are as follows: space group P2₁2₁2₁, a = 10.649(4) Å, b = 15.694(5) Å, c = 30.181(8) Å, R = 6.7% for 3427 data (| F₀| > 3σF) observed to 0.9 Å. Nuclear magnetic resonance studies in CDCl₃ using NH group solvent accessibility and nuclear Overhauser effects as probes are consistent with a 3 ₁₀-helical conformation. In contrast, in (CD₃)₂SO, unfolding of the central segment results in a multiple β-turn structure, with β-turn conformations populated at residues 1–2, 3–4, and 6–7. CD studies in methanol-2,2,2-trifluoroethanol (TFE) mixtures also provide evidence for a solvent-dependent structural transition. Helical conformations are populated in TFE, while type II β-turn structures are favored in methanol. © 1996 John Wiley & Sons, Inc.     

Omega amino acids in peptide design: incorporation into helices

Incorporation of easily available achiral ω-amino acid residues into an oligopeptide results in substitution of amide bonds by polymethylene units of an aliphatic chain, thereby providing a convenient strategy for constructing a peptidomimetic. The central Gly-Gly segment of the helical octapeptide Boc-Leu-Aib-Val-Gly-Gly-Leu-Aib-Val-Ome(1) has been replaced by δ-amino-valeric acid (δ-Ava) residue in the newly designed peptide Boc-Leu-Aib-Val-δ-Ava-Leu-Aib-Val-OMe(2). ¹H-nmr results clearly suggest that in the apolar solvent CDCl₃, the δ-Ava residue is accommodated into a folded helical conformation, stabilized by successive hydrogen bonds involving the NH groups of Val(3), δ-Ava(4), and Leu(5). The δ-Ava residue must adopt a gauche-gauche-trans-gauche-gauche conformation along the central polymethylene unit of the aliphatic segment, a feature seen in an energy-minimized model conformation based on nmr parameters. The absence of hydrogen bonding functionalities, however, limits the elongation of the helix. In fact, in CDCl₃, the folded conformation consists of an N-terminal helix spanning residues 1–4, followed by a Type II β-turn at residues 5 and 6, whereas in strongly solvating media like (CD₃)₂SO, the unfolding of the N-terminal helix results in β-turn conformations at Leu(1)-Aib(2). The Type II β-turn at the Leu(5)-Aib(6) segment remains intact even in (CD₃)₂SO. CD comparisons of peptides 1 and 2 reveal a “nonhelical” spectrum for 2 in 2,2,2-trifluoroethanol. © 1996 John Wiley & Sons, Inc.     

Cellular stabilization of the melatonin rhythm enzyme induced by nonhydrolyzable phosphonate incorporation

Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AANAT) controls daily changes in the production and circulating levels of melatonin. Here, the significance of the phosphorylation of AANAT was studied using a semisynthetic enzyme in which a nonhydrolyzable phosphoserine/threonine mimetic, phosphonomethylenealanine (Pma), was incorporated at position 31 (AANAT-Pma31). The results of studies in which AANAT-Pma31 and related analogs were injected into cells provide the first direct evidence that Thr31 phosphorylation controls AANAT stability in the context of the intact cells by binding to 14-3-3 protein. These findings establish Thr31 phosphorylation as an essential element in the intracellular regulation of melatonin production. The application of Pma in protein semisynthesis is likely to be broadly useful in the analysis of protein serine/threonine phosphorylation.     

Combination of all-<Emphasis Type="Italic">trans</Emphasis> retinoic acid and taxol regressed glioblastoma T98G xenografts in nude mice

Glioblastoma is the most prevalent and highly malignant brain tumor that continues to defy current treatment strategies. This investigation used all-trans retinoic acid (ATRA) and taxol (TXL) as a combination therapy for controlling the growth of human glioblastoma T98G xenografted in athymic nude mice. Histopathological examination revealed that ATRA induced differentiation and combination of ATRA and TXL caused more apoptosis than either treatment alone. Combination therapy decreased expression of telomerase, nuclear factor kappa B (NFκВ), and inhibitor-of-apoptosis proteins (IAPs) indicating suppression of survival factors while upregulated Smac/Diablo. Combination therapy also changed expression of Bax and Bcl-2 proteins leading to increased Bax:Bcl-2 ratio, mitochondrial release of cytochrome c and apoptosis-inducing factor (AIF), and activation of caspase-9. Increased activities of calpain and caspase-3 degraded 270 kD α-spectrin at the specific sites to generate 145 kD spectrin breakdown product (SBDP) and 120 kD SBDP, respectively. Further, increased activity of caspase-3 cleaved inhibitor-of-caspase-activated DNase (ICAD). In situ double immunofluorescent labelings showed overexpression of calpain, caspase-12, caspase-3, and AIF during apoptosis, suggesting involvement of both caspase-dependent and caspase-independent pathways for apoptosis. Our investigation revealed that treatment of glioblastoma T98G xenografts with the combination of ATRA and TXL induced differentiation and multiple molecular mechanisms for apoptosis.