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     

Prostanoid formation in primary astroglial cell cultures: Ca-dependency and stimulation by A 23187, melittin and phospholipases A2 and C

Prostaglandin (PG) and thromboxane B₂ (TXB₂) biosynthesis was studied in cultured astrocytes from neonatal rat brain hemispheres. After two weeks of cultivation, prostanoids were formed with the spectrum: PGD₂ > TXB₂ > PGF₂ > PGE₂, as measured by specific radioimmunoassays. Under basal conditions PGD₂ biosynthesis (9.55 ng/mg protein/15 min) was in the same order of magnitude as the sum of the other prostanoids. The formation of prostanoids was stimulated in a concentration dependent manner (up to 6–10 fold) by the calcium ionophore A 23187 (0.01–10 μM) as well as by melittin (0.01–5 μg/ml), phospholipase A₂ (10–40 U/ml) and phospholipase C (0.01–1 U/ml). Basal and evoked PG and TXB₂ biosynthesis depended on the availability of Ca²⁺, as demonstrated in Ca²⁺ free incubation medium containing Na₂EDTA (1 μM), or with verapamil (100 μM) and 3,4,5-trimethoxybenzoic acid-8-(diethylamino)-octylester-HCl (TMB-8, 1–100 μM). Indomethacin (10 μM), mepacrine (100 μM) and p-bromophenacylbromide (50 μ M) inhibited basal and evoked PG formation. Thin-layer chromatography (TLC) detection after incubation of the cells with [³H]arachidonic acid (1 μCi/ml, for 60 min) confirmed the results obtained by radioimmunoassay. Incubation of [³H]arachidonic acid labelled cells with inonophore or phospholipases, followed by lipid extraction and TLC, showed that A 23187 liberated [³H]arachidonic acid predominantly from phosphatidylethanolamine, whereas phospholipase A₂ and C reduced mainly the labelling of the phosphatidyl-inositol/-choline fraction. Potassium depolarization of the cells did not enhance prostanoid formation. Similarly, drugs with affinity to - or β-adrenoceptors, or to dopamine-, 5-hydroxytryptamine-, muscarine-, histamine-, glutamate-, aspartate-, GABA, adenosine- and opioid-receptors failed to stimulate prostanoid biosynthesis. Also compounds like angiotensin, bradykinin and thrombin were ineffective in this respect.

In conclusion, our results confirm that cultured astrocytes possess the complete pattern of enzymes necessary for prostanoid formation and hence might play a crucial role in brain prostanoid biosynthesis. Stimulation of prostanoid biosynthesis involves Ca²⁺-dependent activation of phospholipase A₂, cyclooxygenase reaction and further PG metabolism. However, the endogenous stimulus for enhanced prostanoid synthesis in the brain still has to be established.     

Phases of degeneracy of the genetic code

The universally valid genetic code is the final result of a multi-stage course of development. Degeneracy, as an important property of the genetic code, was possibly not yet present in the earliest code, first appearing at a later stage of development (Code III). Possibly this step in development is coupled with the presence of a total of four amino acid groups (L, I, E, F). Each group contains a specific number of amino acid (AL, AI, AE, AF). Amino acid groups: - (L) hydrophobic - (I) weakly hydrophobic or polar but uncharged - (E) hydrophilic, acidic - (F) hydrophilic, basic - (D) hydrophobic, aromatic (only in Code IV and Code M. This group is not considered in the calculations below.) In a subsequent stage of development the number of amino acids increases further. At the same time the code becomes more degenerate. The universal genetic code is characterized by three constants of being degenerate. Its immediate predecessor has linear degeneration with two constants. The mitochondrial code represents a transitional form between these two codes.     

On the origin ofVeronica persica (Scrophulariaceae)—a contribution to the history of a neophytic weed

A character analysis reveals a clearly intermediate position of the tetraploidV. persica (2n = 28) between the two diploid speciesV. polita andV. ceratocarpa (both 2n = 14) which are morphologically rather different and have been placed by several authors in different sections of the genus.V. ceratocarpa is native to subhumid deciduous forests of the Caucasus and of the Elburz mountains (N. Iran);V. polita has its centre of variation in the Elburz range where it grows in therophyte habitats. Three other closely related species,V. bungei, V. siaretensis, andV. francispetae, are endemic to the Elburz range which is the main centre of diversity and variability of theV. agrestis group. This comprises all the above mentioned species and also two more European weeds:V. agrestis andV. opaca. Veronica polita, was probably originally native to open places in deciduous mountain forests, before becoming a weed in neolithic times and migrating to Europe; nowadays it has an almost world-wide distribution. The allotetraploidV. persica combines the ecological characters of its parents, the slightly xerophyticV. polita and the more mesophyticV. ceratocarpa, thus being preadapted to become a highly successful weed with a large ecological range. It has spread rapidly almost all over the world since the early 19th century.Dedicated to Hofrat Univ.-Prof. DrKarl Heinz Rechinger on the occasion of the 80th anniversary of his birthday.     

Effects of age and physical performance capacity on distribution and composition of high-density lipoprotein subfractions in men

The influences of age and maximal aerobic capacity (VO2max) on serum lipoproteins with special regard to the concentration, composition and distribution of high density lipoprotein (HDL) subfractions were investigated in 51 healthy males of different characteristics: younger than 35 years, untrained (n = 14, mean age 28.2 years, SD 6.0; VO2max, 47.9 ml.kg-1.min-1, SD 5.8) and trained (n = 11, mean age 27.9 years, SD 4.3; VO2max, 61.1 ml.kg-1.min-1, SD 5.1), older than 50 years untrained (n = 14, mean age 58.9 years, SD 5.9, VO2max, 29.3 ml.kg-1.min-1, SD 5.3) and trained (n = 12, mean age 59.3 years, SD 7.2, VO2max, 45.7 ml.kg-1.min-1, SD 7.7). The fasting-state serum concentrations of total cholesterol, tri-acylglycerol and lipoprotein-cholesterol were measured. The HDL-subfractions were separated by density (rho) gradient ultracentrifugation. Concentrations of cholesterol, cholesterylester, tri-acylglycerol, phospholipids, apolipoprotein (apo) A-I and A-II were measured in the subfractions HDL2b: rho = 1.063-1.100 g.ml-1; HDL2al: rho = 1.00-1.110 g.ml-1; HDL2a2: rho = 1.110-1.150 g.ml-1; HDL3: rho = 1.150-1.210 g.ml-1. Elderly untrained subjects showed increased serum concentrations of total-, very low- and low density lipoprotein-cholesterol and elevated tri-acylglycerol levels. The HDL-cholesterol concentration was decreased, due to reduced concentrations of HDL2-subfractions. Significant changes in the composition of HDL2-subfractions were found in elderly untrained subjects. The HDL2-subfractions had more protein, a decreased apoA-I:A-II ratio and less phospholipids in comparison to HDL2-subfractions from younger untrained and trained, and elderly trained subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasmids in toxic and nontoxic strains of the cyanobacteriumMicrocystis aeruginosa

The plasmid content and toxicity of nine different strains ofMicrocystis aeruginosa have been analyzed. The two toxic strains of the HUB Culture Collection were found to carry each two plasmids, pMA1 and pMA2, of 2.9 kb and 8.5 kb, respectively. In strains PCC 7813 and PCC 7820, also toxic, two different plasmids of 2.6 kb and 16 kb were detected. Hybridization experiments showed that there exists no sequence homology between the pMA plasmids and the plasmids found in the PCC strains; but the pMA plasmids hybridized to chromosomal DNA of the toxic strains PCC 7820, PCC 7813, HUB 063, and the nontoxic strain HUB 5-3. In nontoxic strains no or at most one plasmid of unstable occurrence could be detected. Only one of the toxic strains investigated, SAG 14.85 (NRC-1), contained no plasmid.     

Simultaneous saccharification and protein enrichment fermentation of sugar beet pulp

Summary A product with 40 % protein content was obtained from sugar beet pulp (1.25–2.0 mm) in 48 h one stage (simultaneous) saccharification/fermentation process under optimized conditions using a specific enzyme mixture andCandida tropicalis strain, also saving about 40 % enzymes in comparison to a 2-stage process.     

Selection of preculture conditions for solid state fermentation of sugar beet pulp

Summary For the protein upgrading of sugar-beet pulp in solid state fermentation byTrichoderma reesei andFusarium oxysporum, serveral conditions were studied to prepare an economical preculture for large scale process. The best performance was shown by a preculture obtained in 24 h from 1.5 % molasses solution at pH 4.5–5.0 with 1.0 % milled beet pulp.     

Oxygen binding properties,capillary densities and heart weights in high altitude camelids

Summary The oxygen binding properties of the blood of the camelid species vicuna, llama, alpaca and dromedary camel were measured and evaluated with respect to interspecific differences. The highest blood oxygen affinity, not only among camelids but of all mammals investigated so far, was found in the vicuna (P₅₀=17.6 Torr compared to 20.3–21.6 Torr in the other species). Low hematocrits (23–34%) and small red blood cells (21–30 m³) are common features of all camelids, but the lowest values are found in theLama species. Capillary densities were determined in heart and soleus muscle of vicuna and llama. Again, the vicuna shows exceptional values (3720 cap/mm² on average in the heart) for a mammal of this body size. Finally, heart weight as percent of body weight is higher in the vicuna (0.7–0.9%) than in the other camelids studied (0.5–0.7%). The possibility that these parameters, measured in New World tylopodes at sea level, are not likely to change considerably with transfer to high altitude, is discussed.In the vicuna, a unique combination of the following features seems to be responsible for an out-standing physical capability at high altitude: saturation of blood with oxygen in the lung is favored by a high blood oxygen affinity, oxygen supply being facilitated by low diffusion distances in the muscle tissue. Loading, as well as unloading, of oxygen is improved by a relatively high oxygen transfer conductance of the red blood cells, which is due to their small size and which compensates the negative effect of a low hematocrit on the oxygen conductance of blood. Blood oxygen transport is presumably favored by two factors: a relatively large heart mass and, as a result of low hematocrit, a low blood viscosity. Both are advantageous for achieving a high maximal cardiac output.