A multiple chemostat system for consortia studies on microbially influenced corrosion

A multiple chemostat system has been developed in which metal specimens can be exposed to a consortium of bacteria. The system comprises a single test chemostat containing the test specimen operated at a high dilution rate to facilitate the wash out of planktonic bacteria, selecting for attached or biofilm growth. This chemostat is fed at a steady low rate by a number of separate chemostats each of which contains a pure axenic culture of one member of the consortium being tested. This system has the advantage of providing a continual inoculum of the test species to the test specimen allowing both aerobic and anaerobic bacteria to be grown in the same system. Constant levels of three bacterial types were maintained in the system: Pseudomonas aeruginosa, Thiobacillus ferrooxidans and Desulfovibrio vulgaris. Exposure of 316L stainless steel electrodes to this system resulted in increased corrosion of coupons exposed biotically, as compared to those exposed abiotically. A current monitoring technique and electrochemical impedance spectroscopy were used to evaluate effects of bacteria on metallic corrosion.     

The characterisation of liposomes with covalently attached proteins

The problem of characterising liposomes with covalently attached proteins has been analysed theoretically in terms of a normal weight distribution of liposome diameters. The polydispersity of protein conjugation is considered in terms of the width (standard deviation) of the liposome size distribution. It is shown that the weight-average number of proteins per liposome is a convenient parameter to use to define the protein content of proteoliposomes. Two types of proteoliposome have been prepared (small unilamellar vesicles and reverse phase evaporation vesicles) in which wheat germ agglutinin is covalently coupled to the liposomal surface. The liposomes cover a range of weight average diameter from 65 to 240 nm and of polydispersity (weight to number average diameter (dw/dn) from 2.6 to 11.4. The liposomes have been characterised by chemical analysis and photon correlation spectroscopy and the results are discussed in terms of the theoretical consequences of an equivalent normal weight distribution of diameters.     

Purification and characterization of arcelin seed protein from common bean

Arcelin, a seed protein originally discovered in wild bean accessions, was purified, characterized, and compared to phaseolin, the major seed protein of common bean, and to phytohemagglutinin (PHA), the major bean seed lectin. Arcelin and PHA has several characteristics in common. Both were glycoproteins having similar subunit M_r, deglycosylated M_r, and amino acid compositions. The two proteins were related antigenically and they had the same developmental timing of accumulation. Arcelin also had some hemagglutinating activity, a characteristic associated with lectins. However, several features distinguished arcelin from PHA. Arcelin had a more basic isoelectric point than PHA, greater numbers of basic amino acid residues, additional cysteine residues, and one methionine residue, which PHA lacks. Native PHA protein is a tetramer of subunits, and although a small component of native arcelin protein was also tetrameric, most of the arcelin preparation was dimeric. The hemagglutinating activity of arcelin was specific only for some pronase-treated erythrocytes. It did not agglutinate native erythrocytes, nor did it bind to thyroglobulin or fetuin affinity resins as did PHA. Although arcelin has lectin-like properties, we believe the distinctions between arcelin and PHA warrant the designation of arcelin as a unique bean seed protein.     

The acute effect of 30 min of moderate exercise on high density lipoprotein cholesterol in untrained middle-aged men

Fifteen middle-aged, untrained (defined as no regular exercise) men (mean age 49.9 years, range 42-67) cycled on a cycle ergometer at 50 rpm for 30 min at an intensity producing 60% predicted maximum heart rate [(fc,max), where fc,max = 220 - age]. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (Tg) concentrations were measured from fasting fingertip capillary blood samples collected at rest, after 15 and 30 min of exercise, and at 15 min post-exercise. The mean HDL-C level increased significantly from the resting level of 0.85 mmol.l-1 to 0.97 mmol.l-1 (P < 0.05) after 15 min of exercise, increased further to 1.08 mmol.l-1 (P < 0.01) after 30 min of exercise and remained elevated at 1.07 mmol.l-1 (P < 0.01) at 15 min post-exercise. These increases represented changes above the mean resting level of 14.1%, 27.1% and 25.9% respectively. The HDL-C/LDL-C ratio increased significantly from a resting ratio of 0.20 to 0.26 after 30 min of exercise (P < 0.01) and to 0.24 at 15 min post-exercise (P < 0.05). The mean Tg level increased significantly from a resting level of 0.88 mmol.l-1 to 1.05 mmol.l-1 after 15 min, and to 1.06 mmol.l-1 after 30 min of exercise (P < 0.05 at each time). The TC/HDL-C ratio decreased significantly (P = 0.05) after 30 min of exercise and at 15 min post-exercise by 18.8% and 14%, respectively. No significant changes were observed in the levels of TC or LDL-C over time.(ABSTRACT TRUNCATED AT 250 WORDS)     

Phaseolin variability among wild and cultivated common beans (Phaseolus vulgaris) from Colombia

Phaseolin seed protein variability in a group of 8 wild and 77 cultivated common bean (Phaseolus vulgaris) accessions was determined using 1-dimensional SDS/ PAGE and 2-dimensional IEF-SDS/PAGE. Wild common bean accessions exhibited the 'CH' and 'B' patterns, previously undescribed among either wild or cultivated common beans. The cultivated genotypes showed (in decreasing frequency) the previously described 'S,' T,' and 'C phaseolin patterns as well as the new 'B' pattern similar to the pattern identified in a Colombian wild common bean accession. In the northeastern part of the Colombian bean-growing region, the cultivars exhibited almost exclusively an 'S' phaseolin type, while in the south-western part, the 'T' and 'C phaseolin cultivars were more frequent. Seed size analysis indicated that 'T' and 'C' phaseolin cultivars had larger seeds than 'S' and 'B' phaseolin cultivars. Our results suggest that Colombia is a meeting place for Andean and Middle American common bean germplasms, as well as a domestication center for the common bean.     

Bean lectins

Summary Seeds of forty bean cultivars having different lectin types based on two-dimensional isoelectric focusing-sodium dodecyl sulfate polyacrylamide gel electrophoresis (IEF-SDS/PAGE) were analyzed for quantities of lectin, phaseolin and total protein. Significant differences were found among groups of cultivars with different lectin types for the quantity of lectin and phaseolin. Cultivars with more complex lectin types based on IEF-SDS/PAGE tended to have higher quantities of lectin and lower quantities of phaseolin than cultivars with simple lectin types. An association between lectin type and the quantity of lectin and phaseolin was found also in the seeds of F₂ plants that segregated in a Mendelian fashion for two lectin types. Seeds from plants with the complex lectin type had more lectin and less phaseolin than seeds from plants with the simple lectin type. Therefore, the genes controlling qualitative lectin variation also may influence the quantitative variation of lectin and phaseolin. The results of this study are related to other studies on the quantitative variation for seed proteins and to the possible molecular basis for variation in the quantity of lectins in beans.     

Glomerular lysozyme binding in protein-overload proteinuria

Binding of the cationic molecule lysozyme to the glomerular basement membrane and to the glomerular epithelial cell coat was investigated in the glomerulus of normal female Wistar rats and in rats in which heavy proteinuria was induced by the daily administration of 1 g of bovine serum albumin. In normal rats the binding of lysozyme to the anionic groups in the glomerular basement membrane and the cell coat had no effect on the ultrastructure of the glomerular epithelial cell, in particular the foot processes were unchanged. In the proteinuric rats the lysozyme-binding to the glomerular basement membrane and the epithelial cell coat was completely lost in the damaged glomeruli. In the apparently normal glomeruli present in these proteinuric animals binding was similar to that seen in normal rats. These results suggest that in protein-overload proteinuria there is a loss of glomerular anion and hence a reduction in the glomerular charge barrier. This may account, at least in part, for the increased glomerular leak of negatively charged serum albumin in this experimental model of proteinuria.     

The crystal structure of a nonalkenic,cyclic trimer of levoglucosenone

A single-crystal, X-ray diffraction study was performed on a nonalkenic, cyclic trimer (C₁₈H₁₈O₉, 4) of levoglucosenone, in order to confirm its chemical structure. Crystals of 4 are orthorhombic, with unit-cell parameters of a = 792.20, b = 1874.35, c = 2383.02 pm, space group P2₁2₁2₁, and z = 8. The structure was solved by direct methods, and refined by least-squares to R = 0.032, based on 2990 unique reflections. Each asymmetrical unit contains two symmetry-independent molecules of 4 and one of acetone. The previously assigned chemical structure and stereochemistry of 4 were found to be correct.     

Food and feeding habits of the lesser spotted dogfish, Scyliorhinus canicula (L.), in Isle of Man waters

Stomach contents of the lesser spotted dogfish, Scyliorhinus canicula , from Isle of Man waters were investigated. Dogfish fed opportunistically on a wide range of macrobenthic fauna with hermit crabs, cockles and whelks the dominant prey. Items of secondary importance included various crabs, callianassid shrimps, bivalve molluscs, holothurians, polychaetes and, when locally abundant, herring, Clupea harengus . Dogfish predated more heavily on molluscs than reported in previous studies, reflecting the abundance of molluscs in the associated benthic community.
Composition of the diet altered gradually with dogfish size, reliance on small crustaceans declined and consumption of hermit crabs and molluscs increased with growth. Seasonal changes in the composition of the diet were observed. Feeding intensity was greatest during summer, related in part to increased prey availability, and was least during autumn.