Production and Stability Studies of a Neurotoxin Produced by Clostridium sp. RKD

ABSTRACT: A neurotoxigenic Clostridium sp. (RKD) isolated from intestine of decaying fish produced a neurotoxin that was neutralized by botulinum antitoxin (A+B+E) when tested by mouse protection bioassay. An amplicon of expected size (approximately 700 bp) was generated with primers specific for BoNT/B. Toxin was maximally released in the culture supernatant in the late stationary phase and was dependent on media composition. Growth was optimal in trypticase peptone yeast-extract glucose (TPYG) medium in a pH range of 7.5 to 8.0 and at a temperature between 35°C to 40°C while toxin production was optimum at 37°C (3 to 4 × 10³ minimum lethal dose per milliliter) without any protease treatment. There was no correlation between growth and toxin production when cells were grown in media containing different concentrations of NaCl (0% to 5%). Toxin in the culture supernatant was more stable (50% reduction at 50°C in 90 min) than the partially purified fraction. Toxicity was destroyed gradually after increasing the number of freeze-thaw cycles and was almost completely inactivated after 5 cycles. It was completely inactivated by overnight treatment of 1 N NaOH while it retained 1.5% activity with a similar treatment with 1 N HCl.     

A study of antioxidant properties of some varieties of grapes (Vitis vinifera L.)

Grapes (Vitis vinifera L.) are a major fruit crop in the world. Grapes seem to confer health benefits due to their antioxidant activity. We have evaluated the antioxidant potential of 11 grapes varieties from India and nearby Asian countries. The assays employed involve different levels of antioxidant action like ferric reducing antioxidant power, radical scavenging by 1,1-diphenyl-2-picrylhydrazyl, ferrylmyoglobin/2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid, oxygen radical absorbance capacity (ORAC), and inhibition of lipid peroxidation. The total phenolic and flavonoids contents were also estimated. Our study indicates that cv. Mango is the most potent followed by Sharad Seedless. Ethanolic extracts were found to be more effective than aqueous extracts. Cv. Sharad Seedless, Mango, and Manikchaman also had high ORAC values. Their HPLC analysis showed the presence of various antioxidant polyphenols. In conclusion our studies identified some varieties of grapes with high antioxidant activities and showed that their high antioxidant potential may be due to their phenolic and flavonoid contents.     

DE-ASHING OF COALS WITH HIGH GRADIENT MAGNETIC SEPARATION USING ENHANCEMENT OF MAGNETIC PROPERTY.

ABSTRACT

De-ashing of Indian coal samples from Bhojudih, Mandaman and Kusumunda has been studied using High Gradient Magnetic Separation (HGMS(. Coating of the ash particles with magnetite or blue dust brings down the operating magnetic field considerably. The flow velocity has a significant effect on the removal as well as Heat Value Recovery (HVR).     

Surveillance of the quality of turmeric powders from city markets of India on the basis of curcumin content and the presence of extraneous colours

Curcumin, the principal curcuminoid of turmeric, is responsible for its yellow colour and serves as a measure of turmeric quality. The Prevention of Food Adulteration (PFA) Act of India allows only Curcuma longa L. for the production of turmeric powder and prohibits addition of any foreign matter/artificial colour, but it does not specify a minimum curcumin content. The present surveillance was undertaken to study the quality of loose versus branded turmeric powders vis-à-vis curcumin content and the presence of unwarranted extraneous colours from city markets in India using a newly developed two-dimensional high-performance thin-layer chromatography (2D-HPTLC) method. The results show that curcumin content in branded samples ranged from 2.2% to 3.7%, while non-branded samples had from 0.3% to 2.6%. Though none of the branded turmeric powders contained artificial colours, 17% of loose powders showed the presence of extraneous colour metanil yellow, in the range 1.0–8.5 mg g^?1, which may pose health threats. Low curcumin content in the analysed samples may be due to mixing of other curcuma species or their curcumin-depleted matrices and foreign starches as cheaper alternatives. This is supported by the fact that major Indian turmeric trade types are known to possess curcumin contents ranging from 2.1% to 8.6%, with an average of 4.8%. There is thus an urgent need to prescribe realistic curcumin limits for turmeric powder, otherwise there is no obligation on the part of traders to stick to any minimum levels and consumers will keep on getting this nutrient-depleted household spice.     

Electroless deposition of superconducting MgB2 films on various substrates

The superconducting properties of magnesium diboride (MgB₂) films prepared by electroless deposition on various substrates including silver, gold and silicon are reported. In this study, MgB₂ films were fabricated on silver, gold, and silicon using an electroless plating technique, while controlling the redox potential to improve the deposition quality. The structure, morphology, and superconducting properties of the samples were investigated using X-ray diffraction, magnetometry, scanning electron microscopy, and Raman spectroscopy. X-ray diffraction and Raman spectroscopy confirmed that the films are polycrystalline MgB₂ but also contain some impurity phases. All the MgB₂ films show superconducting transitions near 39 K, the value for bulk MgB₂, with the superconducting volume fraction ranging from approximately 1 to 2%. We find a strong dependence of film quality with the oxidation potential of the bath.     

Investigation of cation-deficient quaternary thiospinels: single crystal study of Ag1.4Cr1.47Sn2.53S8

Single crystals of the quaternary thiospinel Ag_1.41(1)Cr_1.47(5)Sn_2.52(5)S₈ have been obtained by heating stoichiometric mixtures of elemental metals and sulfur at 750 °C. Structural analysis by single crystal X-ray diffraction shows that the above phase crystallizes in the space group with a = 10.4142(3) Å (R₁ = 0.0156 and wR₂ = 0.0416). The Ag-deficiency has been confirmed by solving the structures of crystals prepared in different batches and was observed to vary slightly between crystals. Magnetic studies on a monophasic powder sample with a nominal composition of Ag_1.63CrSn₃S₈ indicates anti-ferromagnetic ordering at low temperature. The high temperature susceptibility leads to a magnetic moment of 3.45 B.M. suggesting that chromium exists predominantly in a trivalent state.     

High gradient magnetic separation of china clays

High gradient magnetic separation has proved to be a successful method for removing micron size colouring bodies from china clays. Clays from Chotanagpur, Bihar have been beneficiated to improve its brightness. The effect of field, flow rate and dispersing agents has been studied on both the run of mine (rom) clay and the washed clay. Significant improvement in the brightness of clay has been obtained.     

Photoconducting a-Si:H films grown at high deposition rates by pulsing a VHF 100 MHz discharge

In a novel experiment hydrogenated amorphous silicon films were deposited by modulating the very high frequency (VHF) (100 MHz) discharges, at low frequency (2 Hz) with a nonzero low power level, using pure as well as 25% hydrogen and 25% helium diluted silane as the source gases. During these studies deposition rate is found to depend on the dwell time as in the case of RF pulsed plasma CVD reported earlier by the authors. The films were characterised for optical bandgap, dark and photoconductivity, hydrogen content, microstructure factor, Urbach energy and defect density. The results indicate that, unlike the RF pulsed plasma case, there is an order of magnitude improvement in the photoconductivity of the material due to pulsing the VHF discharges. Urbach energy and defect density studies also indicate an improvement in the film quality. The improvements are more pronounced in diluted silane deposited films. Controlled ion bombardment (of high flux and lower energy) and the resulting ion bombardment induced preparation of the growth surface in the VHF discharges are believed to be the main factors contributing to the observed results. Thus, a more favourable sheath characteristics as obtained during pulsed VHF discharge conditions over RF (13.56 MHz). Silane discharges holds the key to obtain high growth rate deposition of a-Si:H films of acceptable opto-electronic quality     

Src-like adaptor protein (Slap) is a negative regulator of mitogenesis

The Src-like adaptor protein (Slap) is a recently identified adaptor protein containing Src homology 3 (SH3) and SH2 domains. Slap is found in a wide range of cell types and was shown to interact with the Eck receptor tyrosine kinase in a yeast two-hybrid interaction screen [1]. Here, we found that Slap is expressed in NIH3T3 cells and could associate with the activated platelet-derived growth factor (PDGF) receptor. Using mutated versions of the PDGF receptor and phosphopeptide competition experiments, we determined that Slap has the highest affinity for the Src-binding site of the PDGF receptor. Our inability to produce cell lines that stably expressed Slap suggested that Slap inhibited cell growth. We further investigated this issue by transiently expressing Slap by microinjection. Overexpression of Slap by this method inhibited DNA synthesis induced by PDGF and serum, whereas overexpression of the adaptor proteins Grb2 and Shc did not. Finally, microinjection of a Slap antibody into NIH3T3 cells that had been stimulated with suboptimal doses of growth factors potentiated the effects of the growth factors. These data suggest that, unlike other adaptor proteins, Slap is a negative regulator of signalling initiated by growth factors.