Metabolism of resorcinylic compounds by bacteria: alternative pathways for resorcinol catabolism in Pseudomonas putida.

Two strains of Pseudomonas putida isolated by enrichment cultures with orcinol as the sole source of carbon were both found to grow with resorcinol. Data are presented which show that one strain (ORC) catabolizes resorcinol by a metabolic pathway, genetically and mechanistically distinct from the orcinol pathway, via hydroxyquinol and ortho oxygenative cleavage to give maleylacetate, but that the other strain (O1) yields mutants that utilize resorcinol. One mutant strain, designated O1OC, was shown to be constitutive for the enzymes of the orcinol pathway. After growth of this strain on resorcinol, two enzymes of the resorcinol pathway are also induced, namely hydroxyquinol 1,2-oxygenase and maleylacetate reductase. Thus hydroxyquniol, formed from resorcinol, undergoes both ortho and meta diol cleavage reactions with the subsequent formation of both pyruvate and maleylacetate. Evidence was not obtained for the expression of resorcinol hydroxylase in strain O1OC; the activity of orcinol hydroxylase appears to be recruited for this hydroxylation reaction. P. putida ORC, on the other hand, possesses individual hydroxylases for orcinol and resorcinol, which are specifically induced by growth on their respective substrates. The spectral changes associated with the enzymic and nonenzymic oxidation of hydroxyquinol are described. Maleylacetate was identified as the product of hydroxyquinol oxidation by partially purified extracts obtained from P. putida ORC grown with resorcinol. Its further metabolism was reduced nicotinamide adenine dinucleotide dependent.     

Polymorphism and Food Limitation in Three Daphnia carinata Populations

The annual cycles of Daphnia carinata in three fish-free ponds in southern New Zealand (Quarry, Taieri and Raupo Ponds) are described. Although breeding was continuous, the populations were frequently dominated by distinct cohorts and there was a sexual phase in spring. Growth rates, particularly in Quarry Pond, were often slow, and clutch sizes generally small. Egg and neonate sizes changed seasonally, but changes were not closely related to clutch sizes and body lengths. In Taieri Pond and Raupo Pond some D. carinata grew to 6.14 mm and carried clutches of up to 154 eggs. The potentially high fecundity associated with large size makes D. carinata a good coloniser, but our studies showed that it also survives well in poor food conditions by growing slowly and producing only 1–2 eggs per clutch. D. carinata showed marked seasonal polymorphism in tailspine length and development of head crests. In winter, crests were absent and tailspines were short and varied little with body length. Crests were first apparent, and tailspines began to elongate, in early spring, before the first appearance of a notonectid, Anisops wakefieldi. By midsummer, tailspines had increased markedly with body length but the slope of the relationship declined in autumn. Laboratory trials showed that both tailspine length and crest development increased in the presence of Anisops. These increases may be due to water-soluble factor(s) produced by Anisops.     

Expression of the Coxsackievirus and Adenovirus Receptor in Cultured Human Umbilical Vein Endothelial Cells: Regulation in Response to Cell Density

Primary cultures of human umbilical vein endothelial cells (HUVEC) express the human coxsackievirus and adenovirus receptor (HCAR). Whereas HCAR expression in HeLa cells was constant with respect to cell density, HCAR expression in HUVEC increased with culture confluence. HCAR expression in HUVEC was not quantitatively altered by infection with coxsackievirus B.     

Solid-phase 31P NMR spectra of peat and mineral soils,humic acids and soil solution components: influence of iron and manganese

Solid-phase³¹P nuclear magnetic resonance (NMR) offers a direct means to determine the chemical environment of P present in soil and soil fractions. Iron is often a major component in soil and it has been thought that the presence of paramagnetic Fe and Mn in soil components is responsible for loss of resolution in NMR spectra. We have found that the resolution of signals in the solid-phase ³¹P NMR spectra of a Fe- and Mn-rich mineral soil was no worse than that for a series of four peat soils with a comparable concentration of P. Similarly, the resolution in the solid-phase ³¹P NMR spectra of the humic acid from the mineral soil was not much changed by extraction of the humic acid with acetylacetone in diethyl ether which removed around 40% of its Fe and 30% of its Mn. Removal of up to 50% of the Fe from organic rich, freeze-dried soil solutions from a soil catena with different land uses produced little change in spectral resolution. It was concluded that the limitations to resolution in solid-phase ³¹P NMR spectroscopy of soil humic substances do not stem from the presence of paramagnetic substances, but from the variable way P species are physically held in the amorphous milieu of the organic phase. This revised version was published online in June 2006 with corrections to the Cover Date.     

Bio-oxidation of a refractory gold bearing high arsenic sulphide concentrate: A pilot study

Abstract: A modular mobile bioleach pilot plant has been designed and constructed by Coastech Research Inc. The pilot plant was designed to be transported on two flatbed trucks to any location in North America for on-site piloting.The first bioleach demonstration pilot study was completed on a refractory gold bearing high arsenic (7.5% As) sulphide (28.9cf S) flotation concentrate. A production capacity of up to 562 kg per day at a feed solids concentration of approximately 14Of (w/w) solids and overall retention time of 115 h was achieved under steady operating conditions. Sulphide oxidation exceeded 75% while almost complete arsenic solubilization was observed for the final bioleached product. Oxygen and carbon dioxide uptake rates were obtained from off gas analyses. Oxygen uptake rates as high as 0.99 kg h^-1 m³ were observed. A critical dissolved oxygen concentration, to maintain chemical oxidation, within the range of 0.7-1.1 ppm was observed. Carbon dioxide uptake ratcs were decreased at dissolved oxygen concentrations below approximately 0.7-0.5 ppm. Gold extraction was enhanced from approximately 5% for the pretreated flotation concentrate, to in excess of 90% for the final bioleached product. A worker environment monitoring program was undertaken during the pilot plant operation. All samples taken for air-borne and urinary monitoring were below their respective time weighted average exposure limits.     

Nocturnal primates of kibale forest: Effects of selective logging on prosimian densities

To evaluate the potential impact of logging on nocturnal primates, densities ofGalago demidovii, G. inustus, andPerodictus potto were determined in two areas of the Kibale Forest Reserve, Uganda. One of these areas had been logged at a moderate level in the late 1960's, while the second area was relatively undisturbed. The density of the nocturnal primates was lower in the logged area than in the neighboring unlogged area. For the most frequently sighted nocturnal primate,G. demidovii, sightings were spatially clustered both within a year and between years, suggesting that clumped resources and/or social factors were influencing space use.     

NMR q-space analysis of canonical shapes of human erythrocytes: stomatocytes, discocytes, spherocytes and echinocytes

q-Space plots obtained experimentally using pulsed field-gradient stimulated echo (PGSTE) nuclear magnetic resonance (NMR) spectroscopy from water diffusing in red blood cells (RBCs) of different canonical (distinct variant) morphologies have “signature” features. The experimental q-space plots from suspensions of stomatocytes, echinocytes and spherocytes generated chemically had no diffraction features; in contrast a sample of blood from a patient with hereditary spherocytosis showed diffraction minima. To understand the forms of q-space plots, mathematical/geometrical models of discocytes, stomatocytes, echinocytes and spherocytes were used as restricting boundaries in simulations of water diffusion with Monte Carlo random walks. These simulations indicated that diffusion-diffraction minima are expected for each of the cell shapes considered. The absence of diffusion-diffraction minima in stomatocytes generated by dithiothreitol treatment was surmised to be due to non-alignment of the cells with the magnetic field of the NMR spectrometer. Differential interference contrast microscopy images of the chemically generated spherocyte and echinocyte suspensions showed them to be heterogeneous in cell shape. Therefore, we concluded that the shape heterogeneity caused the loss of the diffusion-diffraction features, which were observed in the more homogeneous sample from a patient with hereditary spherocytosis, and in the simulations of homogeneous cell suspensions. This understanding of factors that affect q-space plots from RBC suspensions will assist morphological studies of other cell and tissue types.     

Discovery of novel, potent, and orally active spiro-urea human glucagon receptor antagonists

A novel class of spiro-ureas has been discovered as potent human glucagon receptor antagonists in both binding and functional assays. Preliminary studies have revealed that compound 15 is an orally active human glucagon receptor antagonist in a transgenic murine pharmacodynamic model at 10 and 30 mpk. Compound 15 is orally bioavailable in several preclinical species and shows selectivity toward cardiac ion channels and other family B receptors, such as hGIP1 and hGLP.