Porphyrin in Vogelfedern

Ohne Zusammenfassung     

Influence of activity in a heterogeneous environment on the dynamics of fish growth: an individual-based model of roacl

A spatio-temporal individual-based model (IBM), including bioenergetic principles, is used to investigate how energy costs coupled to activity represent a variable fraction in a heterogeneous environment and how this is related to another energetic criterion, the potential individual growth, under the conditions of a structured environment. With this approach, it is possible to connect simulated spatio-temporal activity patterns with the energetic needs required for these activities. By using simple foraging rules and a modified random walk model it is possible to reproduce spatial distributions and length frequency distributions. The simulated spatial distribution of roach Rutilus rutilus in Lake Belau, Germany, results in a mean weekly activity multiplier [(standard metabolic rate + activity costs) (standard metabolic rate)⁻¹] of 1–9 with deviations >100% during a simulated year. These deviations are of key importance to differences in the growth rate of individual simulated roach.     

Studies on the protolytic reactions coupled with water cleavage in photosystem II membrane fragments from spinach

The protolytic reactions of PSII membrane fragments were analyzed by measurements of absorption changes of the water soluble indicator dye bromocresol purple induced by a train of 10 s flashes in dark-adapted samples. It was found that: a) in the first flash a rapid H⁺-release takes place followed by a slower H⁺-uptake. The deprotonation is insensitive to DCMU but is completely eliminated by linolenic acid treatment of the samples; b) the extent of the H⁺-uptake in the first flash depends on the redox potential of the suspension. In this time domain no H⁺-uptake is observed in the subsequent flashes; c) the extent of the H⁺-release as a function of the flash number in the sequence exhibits a characteristic oscillation pattern. Multiphasic release kinetics are observed. The oscillation pattern can be satisfactorily described by a 1, 0, 1, 2 stoichiometry for the redox transitions S_i S_i+1 (i=0, 1, 2, 3) in the water oxidizing enzyme system Y. The H⁺-uptake after the first flash is assumed to be a consequence of the very fast reduction of oxidized Q₄₀₀(Fe³⁺) formed due to dark incubation with K₃[Fe(CN)₆]. The possible participation of component Z in the deprotonation reactions at the PSII donor side is discussed.Abbreviations A protonizable group at the PSII acceptor side - BCP Bromocresol Purple - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - FWHM Full Width at Half Maximum - Q_A, Q_B primary and secondary plastoquinone at PSII acceptor side - Q₄₀₀ redox group at PSII-acceptor side (high spin Fe²⁺) - P680 Photoactive chlorophyll of PSII reaction center - S_i redox states of the catalytic site of water oxidation - Z redox component connecting the catalytic site of water oxidation with the reaction center     

Association of thrombospondin of endothelial cells with other matrix proteins and cell attachment sites and migration tracks

Different biochemical and cytochemical techniques were applied to characterize the sites of localization of thrombospondin in cultured endothelial cells. The results obtained by [35S]methionine labeling, immunoblotting, immunoprecipitation, fluorescence microscopy, ultracytochemistry, immunogold labeling, and silver enhancement experiments revealed that thrombospondin secreted by endothelial cells is structurally organized together with proteoheparan sulfate in spherical granules at the cell surface. These granules are about 100 to 300 nm in size. Heparin or enzymatic degradation with heparitinase, but not with ABC lyase, release thrombospondin from the cell surface. Fibronectin is expressed in the extracellular matrix of endothelial cells in a fibrillar organization, clearly distinct from the punctate pattern of thrombospondin on the cell surface. Furthermore, secreted thrombospondin is highly enriched together with fibronectin and proteoheparan sulfate in cell attachment sites and in cell migration tracks. In cell migration tracks proteoheparan sulfate more clearly resembles the fibrillar distribution pattern of fibronectin, whereas thrombospondin reveals a rather monodisperse pattern. The obtained data suggest preferential sites of interaction between thrombospondin and heparan sulfate proteoglycans on the cell surface and a participation of thrombospondin in cell adhesion and cell migration.     

Binding and degradation of proteoglycans by cultured arterial smooth muscle cells. II. Binding sites of proteoglycans on the cell surface

Exogenous proteoglycans stained for electron microscopy with colloidal gold and/or cuprolinic blue bind to the surface of cultured arterial smooth muscle cells at two different sites. (I) About 20% of the proteoglycans adsorbed to the cells from the culture medium interact as monomeric and multimeric proteoglycans with smooth or coated membrane areas. (II) The bulk of exogenous proteoglycans exhibits high affinity binding to cell membrane-associated 10 nm fibrils containing or being closely associated with fibronectin and to collagen. It is suggested that the self association of proteoglycans and their binding to the cell membrane and to cell surface-associated fibronectin and collagen are important for maintaining an appropriate micro-environment for the cultured cells.     

Molecular evidence of a lignin peroxidase H8 homologue inFusarium oxysporum

We describe an evidence for the existence of a ligninase isoenzyme H8 in the deuteromyceteFusarium oxysporum on the genomic as well as on the RNA level.     

The biallelica mating type locus ofUstilago maydis: remnants of an additional pheromone gene indicate evolution from a multiallelic ancestor

Thea mating type locus ofUstilago maydis contains the structural genes for a pheromone-based cell recognition system that governs fusion of haploid cells. The locus exists in two alleles, termeda1 anda2. We have completed the analysis of the nucleotide sequences unique toa1 anda2. Within these dissimilar regions we find two short patches of DNA sequence similarity. Interestingly, one of these segments corresponds to the transcribed region of thea1 pheromone precursor. As a result of multiple nucleotide exchanges this sequence does not code for a functional product. The existence of a second pheromone gene in thea2 allele suggests that the present locus had a multiallelic ancestor. In addition, we describe the presence of two additional genes in thea2 allele. We have investigated the role of these genes during mating and pathogenic development and speculate that they might affect mitochondrial inheritance.