Pulse radiolytic oxidation of beta-carotene with halogenated alkylperoxyl radicals in a quaternary microemulsion: formation of retinol

Pulse radiolytically generated halogenated alkylperoxyl radicals, namely CCl3OO*, CBr3OO*, CHCl2OO*, CHBr2OO*, etc. have been employed for a study of the oxidation of beta-carotene in a quaternary microemulsion. All these halogenated alkylperoxyl radicals produce a radical cation (absorption maximum at 840 nm), either via the initial formation of an adduct (absorption maximum at 740 nm), or by direct reaction. There was a considerable blue shift of both absorption peaks in the present system as compared to those earlier reported in non-polar as well as in micellar media. An additional intense absorption peak at approximately 345 nm was noted at a longer time scale and was stable up to 5 ms. On irradiation with a large number of electron pulses, a stable product with an absorption maximum at 315 nm appeared. On excitation at 315 nm, this product gave a fluorescence spectrum with an emission maximum at 525 nm. The absorption and fluorescence spectra of the stable product compared with those of retinol; this was further confirmed by HPLC analysis. A suitable mechanism has been proposed.     

Expression of the Oligodendrocyte-Myelin Glycoprotein by Neurons in the Mouse Central Nervous System

Abstract: The oligodendrocyte-myelin glycoprotein (OMgp) is a 110-kDa glycosylphosphatidylinositol-linked protein that was initially identified as a myelin-specific protein but whose precise function remains unknown. In this study, immunohistochemistry, western blots, in situ hybridization, and northern blots were used to determine the distribution of OMgp in the mouse brain. OMgp is present in a concentration detectable on western blots in the brains of newborn mice, and its concentration gradually increases until day 24 of life. OMgp mRNA is also present in amounts detectable on northern blots in the brains of newborn mice, and its concentration gradually increases until day 21 of life, after which the concentration diminishes a little. Most of the OMgp in the mouse brain appears to be expressed in diverse groups of neurons, but it is particularly prominent in large projection neurons such as the pyramidal cells of the hippocampus, the Purkinje cells of the cerebellum, motoneurons in the brainstem, and anterior horn cells of the spinal cord. However, OMgp is not confined to these cells and is expressed in cells in the white matter as well. The OMgp gene is placed within an intron of the neurofibromatosis type I gene and on the opposite strand. This organization raises the possibility that there may be a relationship between the functions of the products of the two genes. In support of this possibility, we show that within the mouse CNS OMgp and neurofibromin are expressed in the same cell types.     

Structure of the C-terminal domain from Trypanosoma brucei variant surface glycoprotein MITat1.2

The variant surface glycoprotein (VSG) of African trypanosomes has a structural role in protecting other cell surface proteins from effector molecules of the mammalian immune system and also undergoes antigenic variation necessary for a persistent infection in a host. Here we have reported the solution structure of a VSG type 2 C-terminal domain from MITat1.2, completing the first structure of both domains of a VSG. The isolated C-terminal domain is a monomer in solution and forms a novel fold, which commences with a short alpha-helix followed by a single turn of 3(10)-helix and connected by a short loop to a small anti-parallel beta-sheet and then a longer alpha-helix at the C terminus. This compact domain is flanked by two unstructured regions. The structured part of the domain contains 42 residues, and the core comprises 2 disulfide bonds and 2 hydrophobic residues. These cysteines and hydrophobic residues are conserved in other VSGs, and we have modeled the structures of two further VSG C-terminal domains using the structure of MITat1.2. The models suggest that the overall structure of the core is conserved in the different VSGs but that the C-terminal alpha-helix is of variable length and depends on the presence of charged residues. The results provided evidence for a conserved tertiary structure for all the type 2 VSG C-terminal domains, indicated that VSG dimers form through interactions between N-terminal domains, and showed that the selection pressure for sequence variation within a conserved tertiary structure acts on the whole of the VSG molecule.     

Moderate/subclinical calcium deficiency attenuates trabecular mass,microarchitecture and bone growth in growing rats

Adequate dietary calcium (Ca) intake is essential for bone accretion, peak bone mass (PBM) attainment, bone quality and strength during the mammalian growth period. Severe Ca deficiency during growing age results in secondary hyperparathyroidism (SHPT) and poor bone quality and strength. However, the impact of moderate Ca deficiency during rats early growth period on bone health and the reversibility with supplementing calcium later in adult life remains unclear. Female Sprague-Dawley (SD) rats (postnatal 28th day, P28) were initiated either with a moderate calcium-deficient diet (MCD, 0.25% w/w Ca) or a control diet (0.8% w/w Ca, control group) till P70. Thereafter, MCD rats were continued either with MCD diet or supplemented with calcium diet (0.8% w/w Ca, calcium supplemented group, CaS) till P150. Another group (control rats) were fed 0.8% w/w Ca containing diet from P28 till P150.MCD group, as compared to the control group, had significantly reduced serum ionized Ca and procollagen type 1 N-terminal propeptide (P1NP) at P70 while no significant change was observed in serum corrected Ca, inorganic phosphate (P), alkaline phosphatase (ALP), 25-hydroxy vitamin D [25(OH)D], intact parathyroid hormone (iPTH), and urinary C-terminal telopeptide of collagen 1 (CTX-1), Ca, and P. Femoral and tibial metaphysis in MCD rats had significantly reduced linear growth, cortical and trabecular volumetric BMD (vBMD), trabecular microarchitecture (BV/TV%, trabecular thickness, separation and number, structural model index and connectivity density), cortical thickness, and bone stiffness despite the absence of secondary hyperparathyroidism (SHPT). Continued MCD at P70–P150 results in persistence of compromised bone strength while calcium supplementation (CaS group) improved all the parameters related to bone strength and microarchitecture. Our results indicate that uncorrected moderate/subclinical calcium deficiency in growing rats can result in poor bone quality and strength despite the absence of SHPT. This finding could have relevance in children with poor calcium intake in childhood and adolescence.     

Differential mode of attack on membrane phospholipids by an acidic phospholipase A2 (RVVA-PLA2-I) from Daboia russelli venom

An acidic phospholipase A₂ (RVVA-PLA₂-I) purified from Daboia russelli venom demonstrated dose-dependent catalytic, mitochondrial and erythrocyte membrane damaging activities. RVVA-PLA₂-I was non‐lethal to mice at the tested dose, however, it affected the different organs of mice particularly the liver and cardiac tissues as deduced from the enzymatic activities measured in mice serum after injection of this PLA₂ enzyme. RVVA-PLA₂-I preferentially hydrolyzed phospholipids (phosphatidylcholine) of erythrocyte membrane compared to the liver mitochondrial membrane. Interestingly, RVVA-PLA₂-I failed to hydrolyze membrane phospholipids of HT-29 (colon adenocarcinoma) cells, which contain an abundance of phosphatidylcholine in its outer membrane, within 24 h of incubation. The gas-chromatographic (GC) analysis of saturated/unsaturated fatty acids' release patterns from intact mitochondrial and erythrocyte membranes after the addition of RVVA-PLA₂-I showed a distinctly different result. The results are certainly a reflection of differences in the outer membrane phospholipid composition of tested membranes owing to which they are hydrolyzed by the venom PLA₂s to a different extent. The chemical modification of essential amino acids present in the active site, neutralization study with polyvalent antivenom and heat-inactivation of RVVA-PLA₂-I suggested the correlation between catalytic and membrane damaging activities of this PLA₂ enzyme. Our study advocates that the presence of a large number of PLA₂-sensitive phospholipid domains/composition, rather than only the phosphatidylcholine (PC) content of that particular membrane may determine the extent of membrane damage by a particular venom PLA₂ enzyme.     

Reuse of reactive dyes for dyeing of jute fabric

The aim of the work was to find out suitable method of dyeing so that costly reactive dye can be reused without draining them. The bleached jute fabric was dyed with four different class of reactive dyes namely, cold brand, hot brand, vinyl sulphone and high exhaustion (HE) brand. It is found that the two-step two-bath method of reactive dyeing, where exhaustion and fixation step is separated, is most ideal for reuse of dye bath. Separate original samples produced K/S value same as that of original sample and the K/S value of separate reuse sample varied from 50% to 80% of the original sample depending on the class of dye. In case of same bath method, colour yield of original reuse samples varies from only 10% to maximum 30% of the original samples depending on the class of dyes. Reuse of reactive dyes following separate bath method is particularly suitable for higher depth of shade (4% and above). This process not only utilises costly reactive dyes to the maximum extent but it also produces low water pollution as the effluent contain minimum amount of dye. So the process is economic and eco-friendly as well.