Dynamics of Methane Production, Sulfate Reduction, and Denitrification in a Permanently Waterlogged Alder Swamp

The dynamics of sulfate reduction, methane production, and denitrification were investigated in a permanently waterlogged alder swamp. Molybdate, an inhibitor of sulfate reduction, stimulated methane production in soil slurries, thus suggesting competition for common substrates between sulfate-reducing and methane-producing bacteria. Acetate, hydrogen, and methanol were found to stimulate both sulfate reduction and methane production, while trimethylamine mainly stimulated methane production. Nitrate addition reduced both methane production and sulfate reduction, either as a consequence of competition or poisoning of the bacteria. Sulfate-reducing bacteria were only slightly limited by the availability of electron acceptors, while denitrifying bacteria were seriously limited by low nitrate concentrations. Arrhenius plots of the three processes revealed different responses to temperature changes in the slurries. Methane production was most sensitive to temperature changes, followed by denitrification and sulfate reduction. No significant differences between slope patterns were observed when comparing summer and winter measurements, indicating similar populations regarding temperature responses.     

Acetate Production by Methanogenic Bacteria

Methanosarcina barkeri MS and 227 and Methanosarcina mazei S-6 produced acetate when grown on H₂-CO₂, methanol, or trimethylamine. Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same. M. barkeri produced 30 to 75 μmol of acetate per mmol of CH₄ formed, but M. mazei produced only 8 to 9 μmol of acetate per mmol of CH₄.     

Reconstitution of barley photosystem I reveals that the N-terminus of the PSI-D subunit is essential for tight binding of PSI-C

Removal of the peripheral subunits PSI-C, -D and -E from the photosystem I (PSI) complex of barley requires a urea treatment much harsher than required to remove the similar subunits from cyanobacterial PSI. The resulting PSI barley core was reconstituted by addition of the E. coli expressed subunits PSI-C and -D, and PSI-E isolated from barley. Western blotting, flash photolysis and NADP⁺ photoreduction measurements demonstrated complete and specific removal of the three subunits from the core and efficient reconstitution of the complex after addition of PSI-C, -D and -E. Flash photolysis reveals that PSI-D is essential for binding of functional PSI-C to the PSI core. An N-terminally truncated barley PSI-D lacking 24 amino acid residues and thus being without the N-terminal extension characteristic for higher plant PSI-D proteins reconstitutes the PSI core to 50% of the level obtained with intact PSI-D as demonstrated by flash photolysis and NADP⁺ photoreduction measurements. Cyanobacterial PSI-D is functionally equivalent to truncated barley PSI-D with respect to its activity to reconstitute the PSI core. This shows that the N-terminal extension of plant PSI-D plays a key role in binding PSI-C to the core. The plant-specific N-terminus of PSI-D is hypothesized to execute its function through interaction with a plant-specific PSI subunit, possibly PSI-H. An anchoring function of the N-terminus of PSI-D would also explain the harsh treatment needed to obtain a plant PSI core. PSI-E is important for efficient NADP⁺ reduction but does not influence electron transfer to iron-sulphur centres A/B nor binding of PSI-C. The enhancing effect of PSI-E on NADP⁺ reduction is independent of the presence of the N-terminus of PSI-D.     

Type II Transmembrane Serine Proteases

Analysis of genome and expressed sequence tag data bases at the turn of the millennium unveiled a new protease family named the type II transmembrane serine proteases (TTSPs) in a Journal of Biological Chemistry minireview (Hooper, J. D., Clements, J. A., Quigley, J. P., and Antalis, T. M. (2001) J. Biol. Chem. 276, 857–860). Since then, the number of known TTSPs has more than doubled, and more importantly, our understanding of the physiological functions of individual TTSPs and their contribution to human disease has greatly increased. Progress has also been made in identifying molecular substrates and endogenous inhibitors. This minireview summarizes the current knowledge of the rapidly advancing TTSP field.     

Comparative anatomical study of the carotid circulation in gundis, with implications for their evolutionary history

The carotid circulation pattern in gundis (Ctenodactylidae) is examined and compared with that of typical members of the classical rodent suborders. On this basis their probable phylogenetic relationships and systematic position are discussed. Together with other recent investigations, the unique pattern of cephalic arterial supply emphasizes the isolated position of the ctenodactylids.     

Influence of arbuscular mycorrhizal fungi on soil structure and aggregate stability of a vertisol

The influence of arbuscular mycorrhizal (AM) fungi on aggregate stability of a semi-arid Indian vertisol was studied in a pot experiment in which Sorghum bicolor (L.) was grown as test plant for 10 weeks. Pasteurized soil inoculated with AM fungi was studied with pasteurized and unpasteurized soils as references. A part of the soil in each pot was placed in nylon mesh bags to separate effects of roots and hyphae. The sorghum plants were planted outside the mesh bags which permitted AM hyphae to enter while excluding roots. Aggregate stability of the soil was determined by wet-sieving and turbidimetric measurements. Development of the AM fungi was quantified as colonized root length and external hyphal length. Soil exposed to growth of roots and hyphae (outside mesh bags) showed aggregates with larger geometric mean diameter (GMD) in pasteurized soil inoculated with AM fungi than in pasteurized uninoculated soil. There was no significant difference in GMD of the inoculated, pasteurized soil and the unpasteurized soil. No significant effects of inoculation or plant growth were found in pasteurized soil exposed to hyphal growth only (inside the mesh bags). However, the unpasteurized soil had significantly higher GMD than the pasteurized soil, irrespective of plants and inoculum. Turbidimetric measurements of soil exposed to roots and hyphae (outside mesh bags) showed the highest aggregate stability for the inoculated pasteurized soil. These results demonstrate that AM fungi contribute to the stabilization of soil aggregates in a vertisol, and that the effect is significant after only one growing season. The effect was associated with both AM hyphae and the stimulation of root growth by AM fungi. The contribution from plant roots and AM hyphae to aggregate stability of different size fractions is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Biosynthesis of P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate in calf pancreas microsomes

Calf pancreas microsomes incubated with UDP-N-acetyl-D-[14C] glucosamine in the presence of Mn2+ incorporated radioactivity into P1-2-acetamido-2-deoxy-D-glucopyranosyl P2-dolichyl pyrophosphate and P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate. The formation of both glycolipids was enhanced to the same extent by exogenous dolichyl phosphate. Labeled P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate was formed from synthetic P1-2-acetamido-2-deoxy-alpha-D-glucopyranosyl P2-dolichyl pyrophosphate and from prelabeled pancreatic P1-2-acetamido-2-deoxy-alpha-D-glucopyranosyl P2-dolichyl pyrophosphate without the addition of divalent cation. Upon thin layer chromatography, it had the same mobility as synthetic P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate recently synthesized by Warren et al. (Warren, C. D., Herscovics, A., and Jeanloz, R. W. (1977) Carbohydr. Res., in press), but was different from the synthetic compound prepared by Wedgwood et al. (Wedgwood, J. F., Warren, C. D., Jeanloz, R. W., and Strominger, J. L. (1974) Proc. Natl. Acad. Sci. U. S. A. 71, 5022-5026).     

The evaluation of a mass media campaign aimed at weight gain prevention among young Dutch adults

Objective: The objective was to evaluate a 3‐year nationwide mass media campaign aimed at preventing weight gain. The campaign was aimed primarily at raising awareness of the importance of weight‐gain prevention and bringing these issues to the attention of the Dutch public. Research Methods and Procedures: Eleven serial, independent, cross‐sectional, population‐based telephone surveys were used to assess campaign awareness and impact (N ranged between 483 and 493 for each of the 11 surveys). The surveys were conducted before and after six campaign waves. Multiple linear and logistic regression analyses were used to test for trends over time and for differences among the surveys for campaign awareness, message recall, perceived body weight status, overweight‐related risk perceptions, attitudes, perceived social support, self‐efficacy expectations, and motivations for preventing weight gain. Results: Campaign awareness ranged from 61% after the 1st campaign wave to 88.4% after the final wave. The campaign's television broadcasting activities were an important source of campaign awareness, from both the campaign's television commercials and television‐based free publicity. Message recall ranged from 41.9% to 68.1%. Small positive differences were found in attitudes, perceived social support, and intentions for preventing weight gain. Additionally, the results suggest mixed effects on self‐efficacy expectations and a negative effect on risk perception. Discussion: The campaign resulted in high campaign awareness, especially as a result of television commercials and free publicity on television. The results suggest that the campaign was able to create more positive attitudes and motivation but lower risk perceptions and efficacy for preventing weight gain.     

AKAP complex regulates Ca2+ re-uptake into heart sarcoplasmic reticulum

The beta-adrenergic receptor/cyclic AMP/protein kinase A (PKA) signalling pathway regulates heart rate and contractility. Here, we identified a supramolecular complex consisting of the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2), its negative regulator phospholamban (PLN), the A-kinase anchoring protein AKAP18delta and PKA. We show that AKAP18delta acts as a scaffold that coordinates PKA phosphorylation of PLN and the adrenergic effect on Ca(2+) re-uptake. Inhibition of the compartmentalization of this cAMP signalling complex by specific molecular disruptors interferes with the phosphorylation of PLN. This prevents the subsequent release of PLN from SERCA2, thereby affecting the Ca(2+) re-uptake into the sarcoplasmic reticulum induced by adrenergic stimuli.