Photophysics of ruthenium(II) complexes carrying amino acids in the ligand 2,2′-bipyridine and intramolecular electron transfer from methionine to photogenerated Ru(III)

New ruthenium(II) complexes carrying methionine and phenylalanine in the bipyridine ligand, [Ru(bpy)₂(4-Me-4′-(CONH-l-methionine methyl ester)-2,2′-bipyridine)](PF₆)₂ (IV) and [Ru(bpy)₂(4-Me-4′-(CONH-l-phenylalanine ethyl ester)-2,2′-bpy)](PF₆)₂(V) have been synthesized and characterized and their photophysical properties studied. Flash photolysis measurements of complex IV, in the presence of an electron acceptor, methyl viologen (MV²⁺) show that an intermolecular electron transfer from the excited state of Ru(II) in complex IV, to MV²⁺ takes place, forming Ru(III) and the methyl viologen cation radical, MV⁺. The formation of MV⁺ in this system is confirmed using time-resolved transient absorption spectroscopy. This intermolecular electron transfer is followed by intramolecular electron transfer from the thioether moiety (methionine) to the photogenerated Ru(III), regenerating Ru(II).     

Genetic Traits of Vibrio cholerae O1 Haitian Isolates That Are Absent in Contemporary Strains from Kolkata,India

The world''s worst cholera epidemic in Haiti (2010) coerced to trace the origin and dissemination of the causative agent Vibrio cholerae O1 for proper management of cholera. Sequence analysis of the Haitian strain showed several variations in the genes encoding cholera toxin B subunit (ctxB); toxin-co-regulated pilus (tcpA), repeat in toxins (rtxA), quinolone resistance-determining region (QRDR) of gyrase A (gyrA), rstB of RS element along with the change in the number of repeat sequences at the promoter region of ctxAB. Our earlier studies showed that variant tcpA (tcpA CIRS) and ctxB (ctxB7) first appeared in Kolkata during 2003 and 2006, respectively. The present study revealed that a variant rtxA was first isolated in Kolkata during 2004 and probably formed the genetic background for the emergence of the ctxB7 allele as we were unable to detect a single strain with the combination of El Tor rtxA and ctxB7. The variant gyrA was first time detected in Kolkata during 1994. The Kolkata strains contained four heptad repeats (TTTTGAT) in their CT promoter regions whereas Haitian strains carried 5 heptad repeats. Haitian strains had 3 nucleotide deletions at the rstB gene, which is a unique feature of the classical biotype strains. But the Kolkata strains did not have such deletion mutations in the rstB. Our study demonstrated the existence of some Haitian genetic traits in Kolkata isolates along with the dissimilarities in genomic content with respect to rstB and ctxAB promoter region. Finally, we conclude that Haitian variant strain may be evolved due to sequential event in the Indian subcontinent strain with some cryptic modification in the genome.     

Purification of proteins from polyacrylamide gels, free of detergent or dye

A two step procedure recovers proteins from sodium dodecyl sulfate polyacrylamide gels. The proteins are eluted by electrophoretic dialysis. The eluent is then passed through an Amberlite CG-400 anion-exchange resin. The recovery of protein is nearly total. The recovered proteins have no detectable sodium dodecyl sulfate contamination. With gels that have been stained with Coomassie Brilliant Blue R, the procedure recovers the proteins free of the dye. We have used this procedure successfully during the purification of epidermal glycoproteins.     

Interaction of human recombinant alphaA- and alphaB-crystallins with early and late unfolding intermediates of citrate synthase on its thermal denaturation

We have investigated the role of recombinant human alphaA- and alphaB-crystallins in the heat-induced inactivation and aggregation of citrate synthase. Homo-multimers of both alphaA- and alphaB-crystallins confer protection against heat-induced inactivation in a concentration-dependent manner and also prevent aggregation. Interaction of crystallins with early unfolding intermediates of citrate synthase reduces their partitioning into aggregation-prone intermediates. This appears to result in enhanced population of early unfolding intermediates that can be reactivated by its substrate, oxaloacetate. Both these homo-multimers do not form a stable complex with the early unfolding intermediates. However, they can form a soluble, stable complex with aggregation-prone late unfolding intermediates. This soluble complex formation prevents aggregation. Thus, it appears that the chaperone activity of alpha-crystallin involves both transient and stable interactions depending on the nature of intermediates on the unfolding pathway; one leads to reactivation of the enzyme activity while the other prevents aggregation.     

Evaluation of mutagenicity of the antitubercular naphthylglycine hydrazides insalmonella typhimurium

N-(2-naphthyl)glycine hydrazide and N-methyl-N-(2-naphthyl) glycine hydrazide, which inhibitMycobacterium tuberculosis H₃₇ R_V and show activity against experimental tuberculosis, were evaluated for their mutagenic potential inSalmonella typhimurium. Both the compounds at concentration ranges from 0.1 Μgplate to 1000 Μg/plate failed to induce mutations at the histidine locus either directly or after treatment with rat liver homogenate fraction-“S-9”. N-(2-naphthyl)glycine hydrazide and its N-methyl derivative elicited toxicity at concentrations of 500 Μg/plate and 1000 Μg/plate. However, in the presence of the liver homogenate system, reduction in toxicity was noticed probably due to detoxification and/ or conjugation of the compounds. Under the assay conditions employed, standard mutagens like 4-nitroquinoline-N-oxide, 9-aminoacridine and benzo(a)pyrene were positive. The non-mutagenic nature of N-(2-naphthyl)glycine hydrazide and N-methyl-N-(2-naphthyl)glycine hydrazide should enhance their potential for inclusion in treatment protocols for management of tuberculosis     

Volvariella-treated Eucalyptus sawdust stimulates wheat and onion growth

Conversion of sawdust, a major waste generated by the timber industry, to an agricultural supplement was explored. Beds made with a mixture of Eucalyptus sawdust and soil reduced the chlorophyll content and the growth rate of wheat seedlings. However, following treatment with Volvariella volvaceae and urea, the sawdust in growth beds enhanced both the chlorophyll content and growth of wheat seedlings. Application of treated sawdust to soil increased the biomass of both bulb and foliage of onion. This represents a small beginning in the conversion of an industrial solid waste into a soil conditioner for enhancing agricultural productivity.     

Live non-invasive Shigella dysenteriae 1 strain induces homologous protective immunity in a guinea pig colitis model

A non-invasive live transconjugant Shigella hybrid (LTSHΔstx) strain was constructed from a Shiga toxin gene deleted mutant of Shigella dysenteriae 1 by introducing a plasmid vector pPR1347 that carried a lipopolysaccharide biosynthesis gene (rfb and rfc) of Salmonella typhimurium. In guinea pigs, four successive oral administrations of LTSH Δstx showed complete protection against rectal challenge with wild type S. dysenteriae 1 strain. Exponential increase of the serum IgG and IgA titer against lipopolysaccharide of LTSH Δstx was observed during immunization, peaked on day 28 and remained at that level until day 35 after the initiation of the immunization. In intestinal lavage of the immunized animals, significant increase of IgA titer against lipopolysaccharide of LTSH Δstx was also observed. These data suggested that LTSH Δstx could be a useful candidate to induce protective immunity against S. dysenteriae 1 infection.     

LIN28A: A multifunctional versatile molecule with future therapeutic potential

An RNA-binding protein, LIN28A was initially discovered in nematodes Caenorhabditis elegans and regulated stem cell differentiation and proliferation. With the aid of mouse models and cancer stem cells models, LIN28A demonstrated a similar role in mammalian stem cells. Subsequent studies revealed LIN28A’s roles in regulating cell cycle and growth, tissue repair, and metabolism, especially glucose metabolism. Through regulation by pluripotency and neurotrophic factors, LIN28A performs these roles through let-7 dependent (binding to let-7) or independent (binding directly to mature mRNA) pathways. Elevated LIN28A levels are associated with cancers such as breast, colon, and ovarian cancers. Overexpressed LIN28A has been implicated in liver diseases and Rett syndrome whereas loss of LIN28A was linked to Parkinson’s disease. LIN28A inhibitors, LIN28A-specific nanobodies, and deubiquitinases targeting LIN28A could be feasible options for cancer treatments while drugs upregulating LIN28A could be used in regenerative therapy for neuropathies. We will review the upstream and downstream signalling pathways of LIN28A and its physiological functions. Then, we will examine current research and gaps in research regarding its mechanisms in conditions such as cancers, liver diseases, and neurological diseases. We will also look at the therapeutic potential of LIN28A in RNA-targeted therapies including small interfering RNAs and RNA-protein interactions.