Temperature dependence of energy transfer from the long wavelength antenna BChl-896 to the reaction center in Rhodospirillum rubrum,Rhodobacter sphaeroides (w.t. and M21 mutant) from 77 to 177K,studied by picosecond absorption spectroscopy

Decay of the bacteriochlorophyll excited state was measured in membranes of the purple bacteria Rhodospirillum (R.) rubrum, Rhodobacter (Rb.) sphaeroides wild type and Rb. sphaeroides mutant M21 using low intensity picosecond absorption spectroscopy. The excitation and probing pulses were chosen in the far red wing of the long wavelength absorption band, such that predominantly the minor antenna species B896 was excited. The decay of B896 was studied between 77 and 177K under conditions that the traps were active. In all species the B896 excited state decay is almost temperature independent between 100 and 177K, and probably between 100 and 300 K. In this temperature range the decay rates for the various species are very similar and close to 40 ps. Below 100 K this rate remains temperature independent in Rb. sphaeroides w. t. and M21, while in R. rubrum a steep decrease sets in. An analysis of this data with the theory of nuclear tunneling indicates an activation energy for the final transfer step from B896 to the special pair of 70cm^-1 for R. rubrum and 30cm^-1 or less for Rb. sphaeroides.Abbreviations B880 and B896 the main and long wavelength bacteriochlorophyll's of the LH-1 antenna - RC reaction centre - P special pair in the RC     

Genetic structure, habitat fragmentation and bottlenecks in Danish bank voles (Clethrionomys glareolus)

Tissue-samples from 161 bank voles (Clethrionomys glareolus) collected in three forests (five sampling localities) situated in eastern Jutland (Denmark) were analysed by nine microsatellite loci. The genetic diversity found within the populations was high (H_e=0.753–0.806).Bank voles have specific habitat requirements favouring woodlots, hedgerows and deciduous forests as their prime living area. Hence, a natural or human-induced fragmentation of the forest may cause a sub-structuring of the populations and thereby a restriction of dispersal among populations. The sub-structuring indicated by the observed significant genetic differentiation among the five geographically distinct localities (F_st =0.033, P<0.05) could either result from habitat fragmentation or a combination of home range behaviour and different tree composition in the forests. A road situated between two adjacent forests was not found to exert any barrier effect to the gene flow of bank voles. In one out of five localities investigated, genetic evidence for a recent bottleneck-like situation was found. Bank voles are known to exhibit sometimes huge density fluctuations not only from year to year but also from season to season. The bottleneck-like situation found could therefore be due to the low number of individuals during the low-density phase.     

Receiver bias for colourful signals

Animals tend to respond more strongly to signals that are more colourful and such signals are also common in nature. This is the first study to explore experimentally the possibility that response biases arising in an animal's recognition mechanisms can explain these findings. We trained domestic fowls, Gallus gallus domesticus, to respond by pecking or not pecking to different colours displayed on a touch-sensitive computer screen. The colours changed in response to the birds' choices, which mimicked a simple evolutionary process. Discrimination training generated response biases for the colours more distinct from the nonrewarding colour. As a result the signals evolved towards distinct coloration. The biases developed in directions towards more intense and towards less intense colour, depending on the colour of the nonrewarding stimulus. The result may be applicable to all sorts of visual signals encountered during the same kind of experiences, that is, when one signal should be avoided and another should be approached. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.      

New aspects on the utilization of inorganic sulphate during dentin formation

Summary Single, large doses of ³⁵S-labelled sulphate were administered intravenously to 5 female mice, 7 weeks of age. The animals were killed 10 and 30 min, 4 and 24 h, and 3 days after injection. Decalcified, epoxy-embedded specimens of the upper incisors and molars were subsequently studied by light and electron microscopic autoradiography. In dentin formation, the labelled sulphate passes via the odontoblasts into the predentin. From there, only a small portion enters the mineralised dentin, a large portion being unbound at the mineralising front.     

The scientific impact of the Structural Genomics Consortium: a protein family and ligand-centered approach to medically-relevant human proteins

As many of the structural genomics centers have ended their first phase of operation, it is a good point to evaluate the scientific impact of this endeavour. The Structural Genomics Consortium (SGC), operating from three centers across the Atlantic, investigates human proteins involved in disease processes and proteins from Plasmodium falciparum and related organisms. We present here some of the scientific output of the Oxford node of the SGC, where the target areas include protein kinases, phosphatases, oxidoreductases and other metabolic enzymes, as well as signal transduction proteins. The SGC has aimed to achieve extensive coverage of human gene families with a focus on protein–ligand interactions. The methods employed for effective protein expression, crystallization and structure determination by X-ray crystallography are summarized. In addition to the cumulative impact of accelerated delivery of protein structures, we demonstrate how family coverage, generic screening methodology, and the availability of abundant purified protein samples, allow a level of discovery that is difficult to achieve otherwise. The contribution of NMR to structure determination and protein characterization is discussed. To make this information available to a wide scientific audience, a new tool for disseminating annotated structural information was created that also represents an interactive platform allowing for a continuous update of the annotation by the scientific community.     

Circulating biomarkers of extracellular matrix remodeling and risk of atherosclerotic events

PURPOSE OF REVIEW: Disturbances of the synthesis and breakdown of the extracellular matrix of arterial walls have emerged as key features of the atherosclerotic process. Altered levels of circulating extracellular matrix markers have frequently been observed in relation to manifestations of atherosclerotic disease and its risk factors. RECENT FINDINGS: Research has been focused on the matrix-degrading metalloproteinases, their tissue inhibitors, and procollagen peptides. The most promising matrix metalloproteinase is matrix metalloproteinase-9, which has been observed to predict rapid coronary artery narrowing, ischemic heart disease incidence, abdominal aortic aneurysm expansion, worse outcome in stroke patients, and cardiovascular death. The use of tissue inhibitors of metalloproteinases for prognostication is uncertain thus far. The procollagen marker with most prognostic potential is the marker for type III collagen turnover rate, the N-terminal propeptide PIIINP, higher levels of which predict an adverse outcome after a myocardial infarction and in chronic heart failure, and portend abdominal aortic aneurysm expansion and risk of rupture. Also, the marker for type I collagen synthesis, the C-terminal propeptide PICP, predicts adverse outcomes following myocardial infarction and in chronic heart failure. Extracellular matrix remodeling is also a promising therapeutic target, being favorably affected by several conventional cardiovascular drugs and select dietary interventions. Synthetic matrix metalloproteinase inhibitors are also under development. SUMMARY: Circulating matrix markers have emerged as candidate biomarkers for predicting risk of subsequent atherosclerotic events. Future large longitudinal observational and intervention studies will determine the role of matrix biomarkers in diagnosis and prognostication, and as targets for intervention in cardiovascular diseases.