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Microbiologically influenced corrosion (MIC) is recognized as a considerable threat to carbon steel asset integrity in the oil and gas industry. There is an immediate need for reliable and broadly applicable methods for detection and monitoring of MIC. Proteins associated with microbial metabolisms involved in MIC could serve as useful biomarkers for MIC diagnosis and monitoring. A proteomic study was conducted using a lithotrophically-grown bacterium Desulfovibrio ferrophilus strain IS5, which is known to cause severe MIC in seawater environments. Unique proteins, which are differentially and uniquely expressed during severe microbial corrosion by strain IS5, were identified. This includes the detection of a multi-heme cytochrome protein possibly involved in extracellular electron transfer in the presence of the carbon steel. Thus, we conclude that this newly identified protein associated closely with severe MIC could be used to generate easy-to-implement immunoassays for reliable detection of microbiological corrosion in the field. [ABSTRACT FROM AUTHOR]

Microsomal membranes from etiolated wheat (Triticum aestivum) seedlings cooperatively incorporated xylose (Xyl), arabinose, and glucuronic acid residues from their corresponding uridine 5′-diphosphosugars into an ethanol-insoluble glucurono(arabino)xylan (GAX)-like product. A glucuronyltransferase activity that is enhanced by the presence of UDP-Xyl was also identified in these microsomes. Wheat glucuronyltransferase activity was optimal at pH 7 and required manganese ions, and several lines of evidence suggest its involvement in GAX-like biosynthesis. The GAX characteristics of the 14C-product were confirmed by digestion with a purified endo-xylanase from Aspergillus awamori (endo-xylanase III) and by total acid hydrolysis, resulting in a Xyl:arabinose:glucuronic acid molar ratio of approximately 105:34:1. Endoxylanase III released only three types of oligosaccharides in addition to free Xyl. No radiolabel was released as xylobiose, xylotriose, or xylotetraose, indicating the absence of long stretches of unbranched Xyl residues in the nascent GAX-like product. High-pH anion exchange chromatography analysis of the resulting oligosaccharides along with known arabinoxylan oligosaccharide standards suggests that a portion of the nascent GAX-like product has a relatively regular structure. The other portion of the [14C]GAX-like polymer was resistant to proteinase K, endo-polygalacturonase, and endo-xylanase III (GH11 family) but was degraded by Driselase, supporting the hypothesis that the xylan backbone in this portion of the product is most likely highly substituted. Size exclusion chromatography indicated that the nascent GAX-like polymer had an apparent molecular mass of approximately 10 to 15 kD; however, mature GAXs from wheat cell walls had larger apparent molecular masses (>66 kD). [ABSTRACT FROM AUTHOR]

Primary objective. Elevation of the thrombotic responses mediated by a variety of carbon-derived nanoparticles was recently reported in the literature. In this paper our objective was to investigate whether metal nanoparticles (iron, copper, gold or cadmium sulfide [CdS]) impart such prothrombotic effects on human platelets. Secondly, we wanted to examine whether such effects were mediated through any specific platelet receptor. Experimental design. The size distributions and zeta potentials of characterized gold, copper, iron and CdS (rod & sphere) nanoparticles were measured using photon correlation spectroscopy and laser Doppler velocimetry. The effect of two classes of agonists, adenosine diphosphate (ADP) and epinephrine were studied. To study the effect of ADP, a suboptimal concentration was chosen below a critical concentration. Above the critical concentration, the aggregation assumed its standard hyperbolic shape (and de-aggregation disappeared). Pro-aggregatory action of a given agent can be understood with better sensitivity using a transition from deaggregation to aggregation at this suboptimal agonist level. For epinephrine at low concentration this criticality was absent, however the aggregatory profile showed a delayed response. Two classes of human subjects (a) normal and (b) individuals with acute coronary syndrome, who were under a therapeutic regime of clopidogrel were chosen, as clopidogrel is a specific inhibitor of the low affinity ADP receptor P2Y12. This enabled us to understand the pro-aggregatory effects of nanoparticles with only P2Y1 (high affinity ADP receptor) active. In another set of aggregation experiments, the inhibitor MRS2179 was used to specifically block the high affinity ADP receptor P2Y1. Methods. The threshold ADP concentration was determined using an ADP titration. Nanoparticle rich platelet suspensions were exposed to a previously determined sub-optimal ADP concentration. The experiment was repeated with iron, copper, gold and CdS nanoparticles (later with two different morphologies, rod and sphere). Results. The primary result was that the nanoparticles, composed of various materials and shape features, are likely to impart a pro-aggregatory response in platelets. That the pro-aggregatory effect is not solely a physical self-assembly process and has ADP dependence, is evident from the reversal of the said response by apyrase. The fact that the response was absent in the case of P2Y12 blocked subjects (CdS nanoparticles being an exception) suggests that the low-affinity P2Y12 receptor may be an important target for the nanoparticles. If on the other hand P2Y1 (the high affinity receptor) was blocked by the specific inhibitor MRS2179, nanoparticles could still induce higher aggregation in normal subjects. No significant nanoparticle induced proaggregatory effect was observed for epinephrine. Inference. It is inferred, that the said platelet effect is mediated through ADP receptors, the probable target being the low affinity purinergic receptor P2Y12. The indication is that P2Y12 is a potential target for a wide class of nanoparticles. However the extent of the induced pro-aggregatory effect may be dependent upon the constitutive material and/or the shape of the nanoparticles. This may have important implications in the use of nano-materials in human drug delivery systems. The fact that clopidogrel prevents this nanoparticle mediated prothrombotic effect (with CdS as an exception) may help making nanodrug administration safer. [ABSTRACT FROM AUTHOR]