Fine root biomass,production and turnover in a fertilized <Emphasis Type="Italic">Larix leptolepis</Emphasis> plantation in central Korea

The effects of fertilization [control (C), 200kgNha^–1+25kgP ha^–1 (LNP) and 400kgNha^–1+ 50kgP ha^–1 (HNP)] on fine root dynamics were examined in a 40-year-old Larix leptolepis plantation in central Korea. The average fine root biomass during the growing season for C, LNP and HNP was 957, 934 and 814kgha^–1, respectively, whereas the fine root production for C, LNP and HNP was 2103, 2131 and 2066kgha^–1, respectively. Nitrogen and P inputs into the soil via fine root turnover for C, LNP and HNP were 23.0 and 1.2, 23.3 and 1.2 and 22.6 and 1.2kgha^–1, respectively. There were no significant differences in fine root biomass, production and N and P inputs through fine root turnover between the fertilization treatments during the first growing season after fertilization.     

Carbohydrates of influenza virus. Structure of the oligosaccharides linked to asparagines 406 and 478 in the hemagglutinin of fowl plague virus,strain dutch

Fowl plague virus, strain Dutch, was metabolically labeled withd-[2-³H]mannose, or withd-[6-³H]glucosamine, and the small subunit (HA₂; 0.8 mg in total) of the viral hemagglutinin was isolated by preparative sodium dodecylsulfate-polyacrylamide gel electrophoresis. After proteolytic digestion, the radioactive oligosaccharides were sequentially liberated from the glycopeptides by treatment with different endo--N-acetylglucosaminidases and with peptide:N-glycosidase or, finally, by hydrazinolysis. In this manner, four groups of glycans could be obtained by consecutive gel filtrations and were subfractionated by HPLC. The structures of the individual oligosaccharides were analyzed by micromethylation, by acetolysis or by digestion with exoglycosidases. The major species amongst the high mannose glycans at Ans-406 of the viral glycopolypeptide were found to be Man1-2Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNac1-4GlcNAc and Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNAc1-4GlcNAc, while the complex glycans at Asn-478 are predominantly GlcNAc1-2Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc (lacking, in part, one of the outerN-acetylglucosamine residues) and GlcNAc1-2Man1-3(Gal1-4GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc.Abbreviation BSA bovine serum albumin - endo D (F,H) endo--N-acetyl-d-glucosaminidase D (F,H) - HA hemagglutinin (HA₁, large subunit of HA - HA₂ small subunit - FPV fowl plague virus - PNGase F peptide:N-glycosidase F - SDS sodium dodecylsulfate     

Histochemical studies on the distribution of β-glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of the rat

Summary The present study compares the distribution of -glucuronidase and succinic dehydrogenase in young and old spinal ganglion cells of rat. In young cells there are indications of cyclic activity of these enzymes, i.e., in some stages there are perinuclear concentrations of the enzymes, at other times -glucuronidase and succinic dehydrogenase are uniformly distributed throughout the cytoplasm. These stages have been discussed with the identical distribution of mitochondria. However, in old spinal ganglion cells both -glucuronidase and succinic dehydrogenase become mainly concentrated in the pigment areas, suggesting thereby their possible role in the production of pigment, through the medium of the mitochondria.     

Contextualizing Images in Dreams and Daydreams

A contextualizing image (CI) is a powerful central image of a dream which appears to contextualize (provide a picture-context for) the dreamer's emotion. For instance, dreamers who have experienced any serious traumatic event sometimes dream, I was overwhelmed by a tidal wave. This appears to picture their feeling of terror and/or vulnerability.A scoring system for CIs is examined here and is applied to dreams and daydreams supplied by 40 students. Two raters scoring dreams on a blind basis showed good inter-rater reliability. Recent dreams were shown to have more as well as more intense CIs than recent daydreams; likewise, dreams that stand out had more intense CIs than daydreams that stand out. Students with thin boundaries had more and more intense CIs than students with thick boundaries in their recent dreams and nightmare, but not so clearly in dreams and nightmares that stand out. The emotions judged as contextualized by the powerful images tended towards fear/terror and helplessness/vulnerability in dreams (especially in dreams that stand out) whereas emotions contextualized by images in daydreams showed a wide range with no clusters.     

Characteristics and distribution of β thalassemia haplotypes in South China

Summary Eleven restriction site polymorphisms in the -globin gene cluster were determined in 48 Chinese with homozygous -thalassemia and their parents. Seven haplotypes were identified as associated with the ^thal chromosome and 25 with the ^A chromosome. The distribution of the various ^thal haplotypes in different regions of South China was mapped and discussed in relation to prenatal diagnosis and migration of the Chinese people.     

Photosynthetic oxygen evolution: H/D isotope effects and the coupling between electron and proton transfer during the redox reactions at the oxidizing side of Photosystem II

The oxygen evolving complex (OEC) of Photosystem II (PS II) incorporates a Mn-cluster and probably a further redox cofactor, X. Four quanta of light drive the OEC through the increasingly oxidized states S0 S1 S2 S3 S4 to yield O2 during the transition S4 S0. It has been speculated that the oxidation of water might be kinetically facilitated by the abstraction of hydrogen. This implied that the respective electron acceptor is deprotonated upon oxidation. Whether YZ and X fulfill this expectation is under debate. We have previously inferred a 'chemical' deprotonation of X based on the kinetics of proton release (Haumann M, Drerenstedt W, Hundelt M and Junge W (1996) Biochim Biophys Acta 1273: 237–250. Here, we investigated the rates of electron transfer and proton release as function of the D2O/H2O ratio, the pH, and the temperature both in thylakoids and PS II core particles. The largest kinetic isotope effect on the rate of electron transfer (factor of 2.1–2.4) and the largest pH-dependence (factor of about 2 between pH 5 and 8) was found on S2 S3 where X is oxidized. During the other transitions both factors were much smaller ( 1.4). Electron transfer is probably kinetically steered by proton transfer only during S2 S3. These results corroborate the notion that X serves as a hydrogen acceptor for bound water during S4 S0. We propose a consistent scheme for the final reaction with water to yield dioxygen: two two-electron (hydrogen) transfers in series with a peroxide intermediate.     

Fluorescence detected magnetic resonance of the primary donor and inner core antenna chlorophyll in Photosystem I reaction centre protein: Sign inversion and energy transfer

The Photosystem I reaction centre protein CP1, isolated from barley using polyacrylamide gel electrophoresis showed an EPR (Electron Paramgnetic Resonance) spectrum with the polarisation pattern AEEAAE, typical of the primary donor triplet state ³P700, created via radical pair formation and recombination. ³P700 could also be detected by Fluorescence Detected Magnetic Resonance (FDMR) at _f > 700 nm even in the presence of a large number of chlorophyll antennae. Its zero field splitting parameters, D=282.5×10^-4 cm^-1 and E=38.5×10^-4 cm^-1, were independent of the detection wavelength, and agreed with ADMR (Absorption Detected Magnetic Resonance) and EPR values. The signs of the ³P700 D+E and D-E transitions were positive (increase in fluorescence intensity on applying a resonance microwave field). In contrast, in the emission band 685 < _f < 700 nm FDMR spectra with negative D+E and D-E transitions were detected, and the D value was wavelength-dependent. These FDMR results support an excitation energy transfer model for CP1, derived from time-resolved fluorescence studies, in which two chlorophyll antenna forms are distinguished, with fluorescence at 685 < _f < 700 nm (inner core antennae, F690), and _f > 700 nm (low energy antenna sites, F720), in addition to the P700. The FDMR spectrum in F690 emission can be interpreted as that of ³P700, observed via reverse singlet excitation energy transfer and added to the FDMR spectrum of the antenna triplet states generated via intramolecular intersystem crossing. This would indicate that reversible energy transfer between F690 and P700 occurs even at 4.2 K.Abbreviations Chl chlorophyll - CP1 core chlorophyll protein of Photosystem I - EPR electron paramagnetic resonance - F690, F720 chlorophyll forms having fluorescence maximum at 690–695 and 720 nm, respectively - F(A)(O)DMR fluorescence (absorption) (optical) detected magnetic resonance - FF fluorescence fading - ISC intramolecular intersystem crossing - _f fluorescence emission wave-length - LHC I light harvesting chlorophyll a/b protein of Photosystem I - P700 primary donor of Photosystem I - PS I Photosystem I - RC reaction centre - RP radical pair - SDS sodium dodecyl sulphate - ZFS zero field splitting     

Construction of stable lactose-utilizing Xanthomonas campestris by chromosomal integration of cloned lac genes using filamentous phage ϕLf DNA

Summary Previously, we constructed a lactose-utilizing strain of Xanthomonas campestris, Xc17 (pKMLT), by cloning lacZY genes with the RK2-derived vector pLAFR1. In this study, the narrow-host-range, -galactosidase expression plasmid pKM was fused with an integration vector pS19 to form pSF14. Following insertion into Xc17, pSF14 was integrated into the host chromosome. The integration function was provided by the 0.85-kb EcoRI-PstI fragment from the filamentous phage Lf. The integration caused no adverse effect to the cells and was stable for at least 66 generations without selection. The engineered strain, Xc17::pSF14, was able to grow as well and produce as much xanthan gum in lactose medium as the wild-type cells did in glucose medium, and the Xc17(pKMLT) in lactose medium. Therefore, Xc17::pSF14 is potentially useful for xanthan production by direct use of whey lactose as the fermentation substrate. This study has advanced one more step our efforts to contruct lactose-utilizing X. campestris and confirmed the feasibility of using pS19 as an integration vector.     

Effects of lactation on the regulation of hepatic metabolism in the rat and sheep: adrenergic receptors and cyclic AMP responses

The number and coupling efficiency of -adrenoceptors in liver membranes and intact hepatocytes of lactating and non-lactating female rats were compared to assess whether or not alterations in this signalling system could contribute towards the changed pattern of hepatic metabolism during lactation. In view of the different adaptations of hepatic metabolism to lactation in ruminants, the adrenergic receptor profile of sheep liver membranes was also determined. Post-receptor responses at two stages down-stream of cyclic AMP generation were also evaluated in rat hepatocytes in response to the -adrenergic agonist isoprenaline. No changes in the number or affinity of hepatic -adrenoceptors were found in sheep or rats when lactating and non-lactating individuals were compared. Sheep liver was found to have a much greater concentration of -adrenoceptors than rat liver, and a much higher ratio of :₁. The sensitivity and responsiveness of cyclic AMP generation in response to isoprenaline were similar in hepatocytes prepared from lactating and non-lactating rats, although the response to saturating concentrations of glucagon was diminished in hepatocytes from lactating rats. The activity ratio of cyclic AMP-dependent protein kinase (PK-A) also reacted similarly (in respect of both responsiveness and sensitivity) to isoprenaline in these two groups of hepatocytes. Contrastingly, the sensitivity of rat hepatocyte phosphorylase activity to -adrenergic stimulation was greatly diminished during lactation.     

The polarized UV-absorption spectra and the crystal structure of two different monoclinic crystal forms of the retinal homologue β-8′-apocarotenal

During the visual process, light absorption in the 11-cis retinylidene chromophore leads to a rapid cis-trans-isomerization which initiates the phototransduction step. Important spectroscopic properties of this chromophore can be derived from polarized UV-absorption spectra of crystalline 11-cis-retinal if a parallel X-ray structure analysis is performed. Several questions about the relation between molecular geometry and spectroscopic behavior could not be answered from these spectra. All crystal forms of 11-cis-retinal contain this molecule in its 6-s-cis-ring conformation. For the retinal homologue, -8-apocarotenal (APC), however, two crystal forms with different ring conformation can be grown. The spectrum of -APC (6-s-cis) shows a vibronic structure whereas that of -APC (6-s-trans) is diffuse but has a distinct shoulder on the low energy side of the main band. This S-band is typical for retinal spectra and has been ascribed to a transition into a ¹A _g ^-* -state. The appearance of the S-band is not correlated with a 6-s-cis-conformation as suggested by the retinal spectra but is due to intermolecular interactions: -APC has a dense dimer packing and a strong electrostatic interaction between the -electron systems. This might cause the forbidden ¹A _g ^-* -transition. On the other hand, this interaction is missing in the loose and polar packing of -APC which favors vibration in the polyene chain. This finding is remarkable in view of the photodynamic behavior of the visual chromophore for which strong electrostatic interactions with the protein helices of its binding site have to be postulated.Abbreviations APC 8--Apocarotenal - -APC/-APC /-form of crystallized APC - -CIS/-CIS /-form of crystallized 11-cis-retinal - ATR all-trans retinal - UV ultraviolet light - CI quantum-mechanical calculation employing configuration interaction - PPP-MRD quantum-mechanical calculations after Pariser, Parr, Pople employing multireference determinants - S-bands shoulder on main absorption band - R, S right, left enantiomer - EtOH ethyl alcohol - PE petroleum ether - E direction of electric vector of incident light - b crystallographic b-axis     

Multiple forms of P700-chlorophyll a-protein complexes from Synechococcus sp.: The iron,quinone and carotenoid contents

The iron, quinone and carotenoid contents of five P700-chlorophyll a-protein complexes having different subunit structures (CP1-a,-b,-c,-d and-e) from the thermophilic cyanobacterium Synechococcus sp. were determined. CP1-a,-b,-c and-d that commonly have four polypeptides of 62,000, 60,000, 14,000 and 10,000 dalton contained 10–14 iron atoms per P700, whereas CP1-e that lacks the two small polypeptides was totally devoid of iron. All CP1 complexes contained vitamin K₁ at the molar ratio of vitamin K₁ to P700 of about 2 except CP1-e that had only 0.4 vitamin K₁ per P700. No plastoquinone was detected in five CP1 complexes. Out of four major carotenoids, -carotene, zeaxanthin, caloxanthin, and myxoxanthophyll, present in the thylakoid membranes, only -carotene was found in isolated CP1 complexes; all CP1 complexes contained about 10 -carotene molecules per P700. The flourescence excitation spectrum showed that -carotene serves as an efficient antenna of photosystem I. It is concluded that all iron atoms and a larger fraction of vitamin K₁ molecules present in the photosystem I reaction center complex are associated with the 14,000 and 10,000 dalton polypeptides, whereas -carotene exclusively binds to the large polypeptides which carry the functional and antenna chlorophyll a. The possible functions of iron and vitamin K₁ as electron carriers and of -carotene as the accessary pigment and a photoprotectant in the photosystem I complexes are discussed.     

‘Mental’ in ‘southie’: Individual,family, and community responses to psychosis in South Boston

The deinstitutionalization of psychiatric patients is a deeply cultural as well as political task. It entails the sharing of responsibility for human distress with family and community. Consequently, the locus of social control has also shifted from psychiatric and medical expertise to community and legal institutions. Diagnosis and treatment models must be more compatible with lay explanatory models. This paper explores the various meanings of going mental and being mental in the white, working class, ethnic neighborhood of South Boston. The data are extracted from a study of the impact of deinstitutionalization on a cohort of middle-aged, psychiatric patients discharged from Boston State Hospital in the attempt to return them to community living. Individual, family, and community responses to, and interpretations of, the symptoms of mental distress are discussed. The study indicates that even seriously disturbed individuals are sensitive to cultural meanings and social cues regarding the perception, expression, and content of psychiatric episodes. While madness invariably disenfranchises, it does not necessarily deculturate the individual.     

Electronic excitation transfer in the photosynthetic unit: Reflections on work of William Arnold

Among his many contributions to photosynthesis, William Arnold made critical suggestions about the mechanism of the initial stages of excitation energy transfer and its measurement. Thus he helped found not only the general concept of the photosynthetic unit but also the key idea behind the detailed functional aspects of its chlorophyll antenna. We review the development of these ideas and the modern form in which they have emerged.Abbreviations Chl chlorophyll - Pc phycocyanin - PSU photosynthetic unit - RC reaction center     

Elevated CO2 and temperature effects on soil carbon and nitrogen cycling in ryegrass/white clover turves of an Endoaquept soil

Effects of elevated CO₂ (700 L L^–1) and a control (350 L L^–1 CO₂) on the productivity of a 3-year-old ryegrass/white clover pasture, and on soil biochemical properties, were investigated with turves of a Typic Endoaquept soil in growth chambers. Temperature treatments corresponding to average winter, spring, and summer conditions in the field were applied consecutively to all of the turves. An additional treatment, at 700 L L^–1 CO₂ and a temperature 6°C higher throughout than in the other treatments, was included.Under the same temperature conditions, overall herbage yields in the 700 L L^–1 CO₂ treatment were ca. 7% greater than in the control at the end of the summer period. Root mass (to ca 25 cm depth) in the 700 L L^–1 CO₂ treatment was then about 50% greater than in the control, but in the 700 L L^–1 CO₂+6°C treatment it was 6% lower than in the control. Based on decomposition results, herbage from the 700 L L^–1+6°C treatment probably contained the highest proportion of readily decomposable components.Elevated CO₂ had no consistent effect on soil total C and N, microbial C and N, or extractable C concentrations in any of the treatments. Under the same temperature conditions, it did, however, enhance soil respiration (CO₂-C production) and invertase activity. The effects of elevated CO₂ on rates of net N mineralization were less distinct, and the apparent availability of N for the sward was not affected. Under elevated CO₂, soil in the higher-temperature treatment had a higher microbial C:N ratio; it also had a greater potential to degrade plant materials.Data interpretation was complicated by soil spatial variability and the moderately high background levels of organic matter and biochemical properties that are typical of New Zealand pasture soils. More rapid cycling of C under CO₂ enrichment is, nevertheless, indicated. Futher long-term experiments are required to determine the overall effect of elevated CO₂ on the soil C balance.     

Circadian complexes: Circadian rhythms under common gene control

Summary Circadian rhythms for food and water consumption were measured in five inbred strains of mice under a photoperiod of 16 h light and 8 h dark (16:8 LD), and under constant light (LL).Significant strain differences were observed which indicate that a common gene difference, or set of differences inMus musculus influences both the phase angle () associating the rhythms with the light-dark cycle, and the periods (_LL) of circadian rhythms for food and water consumption. The biological clock mechanism influenced by this genetic variance is common to both food and water circadian rhythms, and differs among the five inbred strains. A positive genetic correlation was observed between the phase angle () and the period (_LL) of each rhythm. This observation can be understood in terms of a functional relationship between phase and period proposed by Pittendrigh and Daan (1976b) for the entrainment of a circadian oscillator by a light-dark cycle in nocturnal rodents.These results suggest that circadian rhythms for food and water consumption in mice are regulated by a common physiological mechanism, and would respond to natural selection as a single circadian complex under common gene control.     

Synthesis of Aminoethyl Glycosides of the Ganglioside GM1 and Asialo-GM1 Oligosaccharide Chains

4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)--D-glucopyranoside with a disaccharide donor, 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-1-thio-2-trichloroacetamido--D-galactopyranoside, in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in a tetrasaccharide, 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, in 69% yield. The complete removal of O-protecting groups in the tetrasaccharide, the replacement of N-trichloroacetyl by N-acetyl group, and the reduction of the aglycone azide group to amine led to the target aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of asialo-GM₁ ganglioside in 72% overall yield. Selective 3-O-glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,6-di-O-benzyl--D-galactopyranosyl)--D-glucopyranoside with thioglycoside methyl (ethyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero--D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid afforded 2-azidoethyl [methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)oate]-(2 3)-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, the selectively protected derivative of the oligosaccharide chain of GM₃ ganglioside, in 79% yield. Its 4-O-glycosylation with a disaccharide glycosyl donor, (4-trichloroacetophenyl-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl) 1-thio-2-trichloroacetamido--D-galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid gave 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-{[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)onate]-(2 3)}-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside in 85% yield. The resulting pentasaccharide was O-deprotected, its N-trichloroacetyl group was replaced by N-acetyl group, and the aglycone azide group was reduced to afford in 85% overall yield aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)-[-D-Neu5Ac-(2 3)]--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of GM₁ ganglioside.     

Theoretical studies on the necessary number of components in mixtures

Summary Theoretical studies on the necessary numbers of components in mixtures (for example multiclonal varieties or mixtures of lines) have been performed according to risk considerations — using the binomial distribution and the Polya-distribution. The risk r of a mixture has been defined as the probability of catastrophic losses (catastrophe = decrease of productivity of q% or more by susceptibilities of the components). Using 1) the binomial distribution and 2) its generalization, the Polya-distribution, and several simplifying assumptions, the risks r = r (x, a, q, n) have been calculated numerically (n = number of components in the mixture, a = parameter for the intensity of contagion and dispersion of susceptibilities (for example: diseases and epidemics), x = probability of susceptibility). The Polya-model reduces to the binomial case if a = 0. The main results are: 1. For each number n of components the risk r decreases markedly with decreasing x (for each q and for each a). 2. For x < = q the risk r decreases with an increasing number n of components (for each a). 3. For each number n of components and x and q with x < q the risk r increases with increasing a. 4. For given q, x and a the functions r = r(n) are asymptotic for larger numbers n of components with n > n^*. In spite of further increasing numbers of components in the mixture the risk remains almost constant. For all situations, where the risk decreases with increasing n these numbers n^*, therefore, can be considered as necessary numbers of components in mixtures, n^* depends on q, x and a. Nevertheless, a global and rough conclusion can be formulated: In many situations one obtains necessary numbers of 30–40 components for a0 and 20–30 components for a = 0.     

Electron transfer from cytochrome f to photosystem I in green algae

The time course of P700⁺ reduction and cytochrome f oxidation following a single-turnover flash excitation of photosystem I was measured under various conditions in different strains of green algae. P700⁺ was reduced with a half-time of 4 s. The rate of cytochrome f oxidation was found to depend widely on physiological factors. Reversible transitions are described from a slow-oxidation state (t _1/2=500 s) to a fast-oxidation state (t _1/2=80 s). The addition of ionophore strongly favours and stabilizes the fast-oxidation state. We suggest that these transitions reflect either reversible association between the cytochrome bf complex and the reaction center of photosystem I or changes in the mobility of oxidized plastocyanin. The transitions might be under the control of the membrane potential or the intracellular ATP content. The relation of these reversible transitions with the light state transitions, and their possible involvement in a switch from linear to cyclic electron transfer, are discussed.Abbreviations cyt cytochrome - DCHC dicyclohexyl-18-crown-6 - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DNP-INT dinitrophenylether of iodonitrothymol - FCCP carbonylcyanide-p-trifluoromethoxyphenylhydrazone - LHC light harvesting complex - PC plastocyanin - PS I photosystem I     

Genetic organization of the E. coli chromosome around the structural gene for initiation factor IF3 (infC).

Summary A set of transducing phages carrying varying lengths of the E. coli chromosome around the structural gene for initiation factor IF3 (infC) was derived from p2 which is known to cary, besides infC, the structural genes for the subunit of phenylalanyl-tRNA synthetase (pheS), the subunit of phenylalanyl-tRNA synthetase (phetT) and the structural gene for threonyl-tRNA synthetase (thrS). The E. coli coding content of these derived phages was analysed by genetic complementation of a set of mutants and by SDS-polyacrylamide gel analysis of the proteins synthesized in UV irradiated cells infected with these phages. The segregation pattern of the different genes among these derived phages indicates that the order of the genes is pheT-pheS-P12-(infC, thrS) where infC is probably between P12 and thrS. P12 is the structural gene of a 12,000 molecular weight unidentified protein.Abbreviations PRS (EC 6.1.1.20) phenylalanyl-tRNA synthetase - TRS (EC 6.1.1.3) threonyl-tRNA synthetase - IF3 Initiation factor IF3 - SDS Sodium dodecyl sulfate - PP^R pyrophosphate resistant - PP^S pyrophosphate sensitive     

Derivatives of Benzotetrazine-1,3-dioxide Are New NO-donors, Activators of Soluble Guanylate Cyclase, and Inhibitors of Platelet Aggregation

The ability of 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides to generate nitric oxide (NO) and activate soluble guanylate cyclase was investigated. All of these compounds were found to be thiol dependent NO-donors and guanylate cyclase activators. The maximal stimulatory effect of 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides was observed at 10 M concentration and the activity increase was 4.5-, 15.0-, and 8.2-fold in the presence of 20 M dithiothreitol and 11.3-, 31.6-, and 20.5-fold, respectively, in the presence of added glutathione (100 M). The NO-dependent mechanism of benzotetrazine-1,3-dioxide nitroderivative-induced activation of soluble guanylate cyclase (in the presence of 100 M glutathione) was confirmed by the inhibition (by 78%) of 7-nitrobenzotetrazine-1,3-dioxide (10 M)-stimulated guanylate cyclase activity in the presence of the NO-scavenger-2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (Carboxy-PTIO, 50 M) and by the inhibition with 1H-[1,2,4 ]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 0.3 M) of 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides (10 M)-stimulated guanylate cyclase by 34, 69, and 39%, respectively. All compounds used inhibited ADP-induced aggregation of human platelets with IC ₅₀ of 10.0, 1.3, and 2.0 M for 5-nitro-, 7-nitro-, and 5,7-dinitrobenzotetrazine-1,3-dioxides, respectively. A clearly defined correlation was established between the ability of the compounds to generate NO, activate soluble guanylate cyclase, and inhibit platelet aggregation.