The effect of Photosystem II inhibitors DCMU and BNT on the high-light induced D1 turnover in two cyanobacterial strains Synechocystis PCC 6803 and Synechococcus PCC 7942

The effect of the Photosystem II (PSII) inhibitors dichlorophenyldimethylurea (DCMU) and bromonitrothymol (BNT) on the rate of the high-light induced D1 protein turnover was studied in whole cells of two cyanobacterial strains Synechocystis PCC 6803 and Synechococcus PCC 7942. In Synechocystis the D1 degradation was slowed down to a similar extent in the presence of either inhibitor compared with control cells. This slower degradation corresponded with the retardation of Photosystem II photoinactivation (PSIIPI) measured as a decline of PS II activity in the illuminated cells treated with chloramphenicol (CAP). The ongoing D1 synthesis in the presence of both PS II inhibitors was confirmed by unchanging PS II activity and the steady-state level of D1 during illumination in the absence of CAP. In Synechococcus cells both DCMU and BNT blocked the turnover of the 'low-light' D1 form (D1:1) but did not prevent the exchange of the 'high-light' form D1:2 for the D1:1 form. The similar effect of both herbicides on the D1 exchange was in contrast with their influence on the rate of PSIIPI. While DCMU had a pronounced protective effect, BNT significantly increased the rate of PS II photodamage. The fast BNT-induced decline of PS II activity was also observed in Synechocystis cells treated with azide, an inhibitor of reactive oxygen species scavenging enzymes. Therefore, we assume that the distinct sensitivity of the two cyanobacterial strains to BNT can be caused by different content and/or activity of these enzymes in each strain.     

Ethylene Glycol Metabolism by Pseudomonas putida

In this study, we investigated the metabolism of ethylene glycol in the Pseudomonas putida strains KT2440 and JM37 by employing growth and bioconversion experiments, directed mutagenesis, and proteome analysis. We found that strain JM37 grew rapidly with ethylene glycol as a sole source of carbon and energy, while strain KT2440 did not grow within 2 days of incubation under the same conditions. However, bioconversion experiments revealed metabolism of ethylene glycol by both strains, with the temporal accumulation of glycolic acid and glyoxylic acid for strain KT2440. This accumulation was further increased by targeted mutagenesis. The key enzymes and specific differences between the two strains were identified by comparative proteomics. In P. putida JM37, tartronate semialdehyde synthase (Gcl), malate synthase (GlcB), and isocitrate lyase (AceA) were found to be induced in the presence of ethylene glycol or glyoxylic acid. Under the same conditions, strain KT2440 showed induction of AceA only. Despite this difference, the two strains were found to use similar periplasmic dehydrogenases for the initial oxidation step of ethylene glycol, namely, the two redundant pyrroloquinoline quinone (PQQ)-dependent enzymes PedE and PedH. From these results we constructed a new pathway for the metabolism of ethylene glycol in P. putida. Furthermore, we conclude that Pseudomonas putida might serve as a useful platform from which to establish a whole-cell biocatalyst for the production of glyoxylic acid from ethylene glycol.     

Investigation of a Family with Autosomal Dominant Dilated Cardiomyopathy Defines a Novel Locus on Chromosome 2q14-q22

Dilated cardiomyopathy (DCM) is a leading cause of heart failure and the most frequent indication for heart transplantation in young patients. Probably >25% of DCM cases are of familial etiology. We report here genetic localization in a three-generation German family with 12 affected individuals with autosomal dominant familial DCM characterized by ventricular dilatation, impaired systolic function, and conduction disease. After exclusion of known DCM loci, we performed a whole-genome screen and detected linkage of DCM to chromosome 2q14-q22. Investigation of only affected individuals defines a 24-cM interval between markers D2S2224 and D2S2324; when unaffected individuals are also included, the critical region decreases to 11 cM between markers D2S2224 and D2S112, with a peak LOD score of 3.73 at recombination fraction 0 at D2S2339. The identification of an additional locus for familial autosomal dominant DCM underlines the genetic heterogeneity and may assist in the elucidation of the causes of this disease.     

Slow Oscillation Amplitudes and Up-State Lengths Relate to Memory Improvement

There is growing evidence of the active involvement of sleep in memory consolidation. Besides hippocampal sharp wave-ripple complexes and sleep spindles, slow oscillations appear to play a key role in the process of sleep-associated memory consolidation. Furthermore, slow oscillation amplitude and spectral power increase during the night after learning declarative and procedural memory tasks. However, it is unresolved whether learning-induced changes specifically alter characteristics of individual slow oscillations, such as the slow oscillation up-state length and amplitude, which are believed to be important for neuronal replay. 24 subjects (12 men) aged between 20 and 30 years participated in a randomized, within-subject, multicenter study. Subjects slept on three occasions for a whole night in the sleep laboratory with full polysomnography. Whereas the first night only served for adaptation purposes, the two remaining nights were preceded by a declarative word-pair task or by a non-learning control task. Slow oscillations were detected in non-rapid eye movement sleep over electrode Fz. Results indicate positive correlations between the length of the up-state as well as the amplitude of both slow oscillation phases and changes in memory performance from pre to post sleep. We speculate that the prolonged slow oscillation up-state length might extend the timeframe for the transfer of initial hippocampal to long-term cortical memory representations, whereas the increase in slow oscillation amplitudes possibly reflects changes in the net synaptic strength of cortical networks.     

20-Hydroxyecdysone prevents oxidative stress damage in adult Pyrrhocoris apterus

Injections of 38 pmol paraquat (1,1'-dimethyl-4,4'-bypyridilium) into adult Pyrrhocoris apterus (average body weight 29.6 mg in males and 36.9 mg in females) caused a significant elevation of lipid peroxidation and protein carbonylation and a decline of membrane fluidity in the microsomal brain fraction. Another manifestation of oxidative stress was a depletion of the reduced glutathione pool and reduction of the gamma-glutamyl transpeptidase activity in the brain extracts. The damaging action of paraquat on the brain was counteracted by simultaneous injection of 1 pmol 20-hydroxyecdysone (20E). 20E restrained lipid peroxidation and the formation of protein carbonyls, ameliorated changes in microsomal membrane fluidity, enhanced the level of reduced glutathione, and upregulated the activity of gamma-glutamyl transpeptidase. At the organismic level, 20E curtailed three detrimental effects caused by paraquat injection: the disappearance of a blood protein, the suppression of fecundity and egg hatchability, and the shortening of adult life span. The data showed that 20E provided a systemic antioxidant protection but the significance of endogenous ecdysteroids in the management of oxidative stress remains to be shown.     

Genetic engineering of the major timothy grass pollen allergen, Phl p 6, to reduce allergenic activity and preserve immunogenicity

On the basis of IgE epitope mapping data, we have produced three allergen fragments comprising aa 1-33, 1-57, and 31-110 of the major timothy grass pollen allergen Phl p 6 aa 1-110 by expression in Escherichia coli and chemical synthesis. Circular dichroism analysis showed that the purified fragments lack the typical alpha-helical fold of the complete allergen. Superposition of the sequences of the fragments onto the three-dimensional allergen structure indicated that the removal of only one of the four helices had led to the destabilization of the alpha helical structure of Phl p 6. The lack of structural fold was accompanied by a strong reduction of IgE reactivity and allergenic activity of the three fragments as determined by basophil histamine release in allergic patients. Each of the three Phl p 6 fragments adsorbed to CFA induced Phl p 6-specific IgG Abs in rabbits. However, immunization of mice with fragments adsorbed to an adjuvant allowed for human use (AluGel-S) showed that only the Phl p 6 aa 31-110 induced Phl p 6-specific IgG Abs. Anti-Phl p 6 IgG Abs induced by vaccination with Phl p 6 aa 31-110 inhibited patients' IgE reactivity to the wild-type allergen as well as Phl p 6-induced basophil degranulation. Our results are of importance for the design of hypoallergenic allergy vaccines. They show that it has to be demonstrated that the hypoallergenic derivative induces a robust IgG response in a formulation that can be used in allergic patients.     

A role for Insulin-like growth factor 2 in specification of the fast skeletal muscle fibre

Background  

Fibre type specification is a poorly understood process beginning in embryogenesis in which skeletal muscle myotubes switch myosin-type to establish fast, slow and mixed fibre muscle groups with distinct function. Growth factors are required to establish slow fibres; it is unknown how fast twitch fibres are specified. Igf-2 is an embryonically expressed growth factor with established in vitro roles in skeletal muscle. Its localisation and role in embryonic muscle differentiation had not been established.     

Acute phase reactants add little to composite disease activity indices for rheumatoid arthritis: validation of a clinical activity score

Introduction  

Frequent assessments of rheumatoid arthritis (RA) disease activity allow timely adaptation of therapy, which is essential in preventing disease progression. However, values of acute phase reactants (APRs) are needed to calculate current composite activity indices, such as the Disease Activity Score (DAS)28, the DAS28-CRP (i.e. the DAS28 using C-reactive protein instead of erythrocyte sedimentation rate) and the Simplified Disease Activity Index (SDAI). We hypothesized that APRs make limited contribution to the SDAI, and that an SDAI-modification eliminating APRs – termed the Clinical Disease Activity Index (CDAI; i.e. the sum of tender and swollen joint counts [28 joints] and patient and physician global assessments [in cm]) – would have comparable validity in clinical cohorts.