Synthesis and crystal structure of a new pyridinium bromide salt: 4-methyl-1-(3-phen-oxy-prop-yl)pyridinium bromide.

In the cation of the title mol-ecular salt, CHNO·Br, the pyridinium and phenyl rings are inclined to one another by 11.80 (8)°. In the crystal, the Br anion is linked to the cation by a C-H⋯Br hydrogen bond.

Redox-sensing iron-sulfur cluster regulators.

Significance: Iron-sulfur cluster proteins carry out a wide range of functions, including as regulators of gene transcription/translation in response to environmental stimuli. In all known cases, the cluster acts as the sensory module, where the inherent reactivity/fragility of iron-sulfur clusters towards small/redox active molecules is exploited to effect conformational changes that modulate binding to DNA regulatory sequences. This promotes an often substantial re-programming of the cellular proteome that enables the organism or cell to adapt to, or counteract, its changing circumstances.

Crystal structures of two mononuclear complexes of terbium(III) nitrate with the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane.

Two new mononuclear cationic complexes in which the Tb ion is bis-chelated by the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane (H, CHO) were prepared from Tb(NO)·5HO and had their crystal and mol-ecular structures solved by single-crystal X-ray diffraction analysis after data collection at 100 K. Both products were isolated in reasonable yields from the same reaction mixture by using different crystallization conditions. The higher-symmetry complex dinitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) nitrate di-meth-oxy-ethane hemisolvate, [Tb(NO)(H)]NO·0.

Mitochondrial-driven sustained active water vapour absorption (WVA) in the firebrat, Thermobia domestica (Packard), during development and the moulting cycle.

Rapid pre-functional mitochondrial biogenesis in the short-lived first-instar nymph occurs in the cells of the developing posterior rectal sacs which when mature are the organs believed to be responsible for sustained active water vapour absorption (WVA) in the firebrat Thermobia domestica (Packard). During the second instar, the mitochondria migrate apically and begin to associate with deep portasome-studded infolds of the apical plasma membrane (apm), just as WVA starts sporadically. By mid to late in the third instar the mature mitochondria-apm apical complex is fully developed, with elongated tubular mitochondria vertically packed hexagonally in transverse section and adpressed to the deeply pleated infolds of the apm, giving the greatest known concentration of mitochondria.

The problems in determining international road mortality.

We examined road traffic crash (RTC) fatality rate data for the year 2002 with the object of determining which data source offered the most reliable estimates for international comparison work. Data from the World Health Organisation (WHO) (supplied by national health authorities) and the International Road Federation (IRF) (supplied by national transport authorities) was compared. There were large discrepancies between the rates reported.

Highly enantioselective total synthesis of (-)-(3'S)-Lomatin and (+)-(3'S,4'R)-trans-khellactone.

Concise highly enantioselective three-step syntheses are described for (-)-(3'S)-lomatin and (+)-(3'S,4'R)-trans-khellactone from 7-hydroxycoumarin in 97% ee and in 57% and 58% overall yields, respectively, using nonaqueous enantioselective epoxidation by an iminium salt as the key step.

Internalization: what does it tell us about pharmacokinetic and pharmacodynamic properties of an antagonist?

Chemokine receptors play an important role in trafficking leukocytes within the body, a process that depends on expression of the receptors on the cell surface. Expression levels are regulated by the rate of internalizing receptor compared to the rate of recycling/recovering receptor. Internalization is commonly induced by binding of agonists to their receptors that in turn use clathrin-coated pits or caveolae to internalize.

An improved dual channel PERCA instrument for atmospheric measurements of peroxy radicals.

This paper describes a new dual-channel PEroxy RadiCal Amplification (PERCA) instrument, which has been designed to improve the time resolution and signal to noise and to reduce the interference caused by variations in ambient ozone concentrations. The instrument was run at the Weybourne Atmospheric Observatory (WAO), North Norfolk, during WAOWEX (Weybourne Atmospheric Observatory Winter Experiment) in January/February 2002 and INSPECTRO (Influence of clouds on the spectral actinic flux in the lower troposphere) in September 2002. The performance of the instrument is assessed and compared to that of a single channel instrument.

Airborne measurements of peroxy radicals using the PERCA technique.

The Peroxy Radical Chemical Amplifier (PERCA) technique is a proven method for measurement of ambient levels of peroxy radicals at ground level, but there are no published instances of the technique being used on an aerial platform. Here we describe deployment of a PERCA on the former UK Meteorological Office C-130 Hercules research aircraft. The instrument uses the established method of chemical amplification and conversion of peroxy radicals to nitrogen dioxide (NO2) by doping the sample air-flow matrix with CO and NO, subsequently measuring the NO2 yield with an improved 'Luminox' LMA-3 NO2 detector.

Characterization of the role of the "MT-loop": an eight-amino acid insertion specific to progelatinase A (MMP2) activating membrane-type matrix metalloproteinases.

Progelatinase A (proGLA) activation is thought to be initiated almost exclusively by the type I transmembrane members of the membrane type matrix metalloproteinase family (MT-MMP): MT1, -2, -3, and -5-MMP (MMP14, -15, -16, and -24). One difference between these enzymes and the other MMP family members is the insertion of eight amino acids between strands betaII and III in the catalytic domain. In MT1-MMP, the best characterized of these enzymes to date, these residues consist of (163)PYAYIREG(170).

Membrane type 4 matrix metalloproteinase (MMP17) has tumor necrosis factor-alpha convertase activity but does not activate pro-MMP2.

Membrane type 4 matrix metalloproteinase (MT4-MMP) shows the least sequence homology to the other MT-MMPs, suggesting a distinct function for this protein. We have isolated a complete cDNA corresponding to the mouse homologue which includes the signal peptide and a complete pro-domain, features that were lacking from the human form originally isolated. Mouse MT4-MMP (mMT4-MMP) expressed in COS-7 cells is located at the cell surface but does not show ability to activate pro-MMP2.

Structural investigation of the molybdenum site of the periplasmic nitrate reductase from Thiosphaera pantotropha by X-ray absorption spectroscopy.

The molybdenum centre of the periplasmic respiratory nitrate reductase from the denitrifying bacterium Thiosphaera pantotropha has been probed using molybdenum K-edge X-ray absorption spectroscopy. The optimum fit of the Mo(VI) EXAFS suggests two ==O, three -S- and either a fourth -S- or an -O-/-N- as molybdenum ligands in the ferricyanide-oxidized enzyme. Three of the -S- ligands are proposed to be the two sulphur atoms of the molybdopterin dithiolene group and Cys-181.

Construction and characterization of Streptomyces coelicolor A3(2) mutants that are multiply deficient in the nonessential hrd-encoded RNA polymerase sigma factors.

Previous studies showed that Streptomyces coelicolor A3(2) has four genes (hrdA, hrdB, hrdC, and hrdD) that appear to encode RNA polymerase sigma factors very similar to the sigma 70 subunit of Escherichia coli and that hrdC and hrdD could be individually disrupted without causing obvious phenotypic defects. Here, hrdA was cloned and stable null hrdA and hrdD mutants were constructed by gene replacement. These two mutants and a previously constructed hrdC null mutant were used in crosses to generate hrdAC, hrdAD, hrdCD, and hrdACD strains.

Isolation and characterization of the major vegetative RNA polymerase of Streptomyces coelicolor A3(2); renaturation of a sigma subunit using GroEL.

The promoter region of the agarase gene (dagA) of Streptomyces coelicolor A3(2) is complex; it consists of four distinct promoters with different -10 and -35 regions. We report the isolation of a form of RNA polymerase that mediates transcription in vitro from the dagAp4 promoter. The core components of this RNA polymerase are associated with a polypeptide of c.

Characterization of a gene conferring bialaphos resistance in Streptomyces coelicolor A3(2).

A gene (bar) was identified adjacent to the hrdD sigma factor gene in Streptomyces coelicolor A3(2). The predicted bar product showed 32.2% and 30.

Cloning, disruption, and transcriptional analysis of three RNA polymerase sigma factor genes of Streptomyces coelicolor A3(2).

The rpoD gene of Myxococcus xanthus was used as a probe to isolate three Streptomyces coelicolor genes, hrdB, hrdC, and hrdD, which appear to encode RNA polymerase sigma factors extremely similar to the sigma 70 polypeptide of Escherichia coli. Gene disruption experiments suggested that hrdB is essential in S. coelicolor A3(2) but showed that hrdC and hrdD mutants are viable and are apparently unaffected in differentiation, gross morphology, and antibiotic production.

Spiracular closing mechanisms in the firebrat, Thermobia domestica (packard) (Thysanura).

Mechanisms for regulating the degree of opening of its spiracles are present in Thermobia. That of the mesothoracic spiracle is of the external type with a flap-like hood guarding the spiracular aperture. Contraction of muscles open the spiracle by raising the hood.

The control of glycolysis in aged slices of carrot root tissue.

The possibility that the rate of glycolysis in aged slices of carrot (Daucus carota L.) is controlled by the enzyme phosphofructokinase was examined, by changing the rate of metabolism, by supplying the tissue with potassium chloride, potassium phosphate and potassium citrate and measuring the subsequent changes in levels of metabolites. Potassium chloride and potassium phosphate stimulate glycolysis, potassium citrate inhibits glycolysis and the associated changes in metabolites are consistent with the view that respiration is controlled by a dual system involving phosphofructokinase and glyceraldehyde phosphate dehydrogenase or possibly phosphoglycerate kinase.

The Pasteur effect in carrot root tissue.

The presence of a Pasteur effect in aged discs of carrot (Daucus carota L.) storage tissue and its apparent absence in fresh discs was confirmed. Changes in the concentration of glycolytic intermediates have been determined, following the transfer of fresh and aged discs from air to nitrogen.

Respiration rates and population metabolism of woodland snails.

Experiments were done to measure the respiration rates of twenty species of terrestrial snail. Acclimatization phenomena were sought in two species, Discus rotundatus and Hygromia striolata, but not detected. The Q between 5 and 15° C for the twenty species varied between 1.