Dependence of the flash-induced oxygen evolution pattern on the chemically and far red light-modulated redox condition in cyanobacterial photosynthetic electron transport

Flash-induced photosynthetic oxygen evolution was measured in cells and thylakoid preparations from the coccoid cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 and from the filamentous cyanobacterium Oscillatoria chalybea. The resulting characteristic flash patterns from these cyanobacteria can be chemically altered by addition of exogenously added substances like CCCP, DCPiP and inorganic salts. Potassium chloride, manganese sulfate and calcium chloride affected the sequences by specific increases in the flash yield and/or effects on the transition parameters. Chloride appeared to exert the strongest stimulatory effect on the oxygen yield. In comparison to chloride, both manganese and calcium did not significantly stimulate the flash amplitudes as such, but improved the functioning of the oxygen evolving complex by decreasing the miss parameter alpha. Particular effects were observed with respect to the time constants of the relaxation kinetics of the first two flash signals Y1/Y2 of the cyanobacterial patterns. In the presence of the investigated chemicals the amplitudes of the first two flash signals (Y2 in particular) were increased and the relaxation kinetics were enhanced so that the time constant became about identical to the conditions of steady state oxygen flash amplitudes. The results provide further evidence against a possible participation of either PS I or respiratory processes to Y1/Y2 of cyanobacterial flash patterns. Dramatic effects were observed when protoplasts from Oscillatoria chalybea or cells from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 were exposed to weak far red background illumination. Under these conditions, Y2 (and to a smaller extent Y1) of otherwise unchanged flash sequences were specifically modified. Y2 was substantially increased and again the relaxation kinetics were accelerated making the signal indistinguishable from a Y(SS) signal. From the mathematical fit of the sequences we conclude that S2 contributes to 10-20% of the S-state distribution (in comparison to 0% in the control). Thus, far red background illumination might represent a valuable means for photosynthetic investigations where high amounts of S2 are required like e. g. EPR measurements. In such experiments the corresponding EPR signals appeared substantially enhanced following far red preillumination (Ahrling and Bader, unpublished observations). Our results clearly show that the 'controversial results' from parts of the literature suggesting the participation of different mechanisms (net oxygen evolution, inhibited uptake processes etc.) are not required to explain the flash-induced oxygen evolution in cyanobacteria: the seemingly 'incompatible' conditions and conformations can be perfectly interconverted by different modulation techniques (chemicals, far red) of the respective redox condition within the water oxidation complex of photosynthesis.     

Nerve Growth Factor Effect on Adenosine Transport in Cultured Chromaffin Cells

Chromaffin cells both recently isolated or in culture present a high-affinity adenosine transporter with a Km value of 1 microM. When cells were exposed to nerve growth factor (NGF; 10 ng/ml), the adenosine transporter affinity decreased to 3 microM. This value was maintained from 3 days after plating to the end of the culture period. A change in the transport capacity was observed, with a significant increase (approximately 200-260%) in NGF-cultured cells throughout the period studied.     

Extensive changes in cytokeratin expression patterns in pathologically affected human gingiva

The stratified squamous epithelium of the oral gingiva and the hard palate is characterized by a tissue architecture and a cytoskeletal composition similar to, although not identical with, that of the epidermis and fundamentally different from that of the adjacent non-masticatory oral mucosa. Using immunocytochemistry with antibodies specific for individual cytokeratins, in situ hybridization and Northern blots of RNA with riboprobes specific for individual cytokeratin mRNAs, and gel electrophoresis of cytoskeletal proteins of microdissected biopsy tissue samples, we show changes in the pattern of expression of cytokeratins and their corresponding mRNAs in pathologically altered oral gingiva. Besides a frequently, although not consistently, observed increase in the number of cells producing cytokeratins 4 and 13 (which are normally found as abundant components in the sulcular epithelium and the alveolar mucosa but not in the oral gingiva) and a reduction in the number of cells producing cytokeratins 1, 10 and 11, the most extensive change was noted for cytokeratin 19, a frequent cytokeratin in diverse one-layered and complex epithelia. While in normal oral gingiva cytokeratin 19 is restricted to certain, sparsely scattered cells of --or near--the basal cell layer, probably neuroendocrine (Merkel) cells, in altered tissue of inflamed samples it can appear in larger regions of the basal cell layer(s) and, in apparently more advanced stages, also in a variable number of suprabasal cells. Specifically, our in situ hybridization experiments show that this altered suprabasal cytokeratin 19 expression is more extended at the mRNA than at the protein level, indicating that cytokeratin 19 mRNA synthesis may be a relatively early event during the alteration. These changes in cytokeratin expression under an external pathological influence are discussed in relation to other factors known to contribute to the expression of certain cytokeratins and with respect to changes occurring during dysplasia and malignant transformation of oral epithelia.     

Connective Tissue Growth Factor Overexpression in Cardiomyocytes Promotes Cardiac Hypertrophy and Protection against Pressure Overload

Connective tissue growth factor (CTGF) is a secreted protein that is strongly induced in human and experimental heart failure. CTGF is said to be profibrotic; however, the precise function of CTGF is unclear. We generated transgenic mice and rats with cardiomyocyte-specific CTGF overexpression (CTGF-TG). To investigate CTGF as a fibrosis inducer, we performed morphological and gene expression analyses of CTGF-TG mice and rat hearts under basal conditions and after stimulation with angiotensin II (Ang II) or isoproterenol, respectively. Surprisingly, cardiac tissues of both models did not show increased fibrosis or enhanced gene expression of fibrotic markers. In contrast to controls, Ang II treated CTGF-TG mice displayed preserved cardiac function. However, CTGF-TG mice developed age-dependent cardiac dysfunction at the age of 7 months. CTGF related heart failure was associated with Akt and JNK activation, but not with the induction of natriuretic peptides. Furthermore, cardiomyocytes from CTGF-TG mice showed unaffected cellular contractility and an increased Ca²⁺ reuptake from sarcoplasmatic reticulum. In an ischemia/reperfusion model CTGF-TG hearts did not differ from controls.Our data suggest that CTGF itself does not induce cardiac fibrosis. Moreover, it is involved in hypertrophy induction and cellular remodeling depending on the cardiac stress stimulus. Our new transgenic animals are valuable models for reconsideration of CTGF''s profibrotic function in the heart.     

Germ-line DNA copy number variation frequencies in a large North American population

Genomic copy number variation (CNV) is a recently identified form of global genetic variation in the human genome. The Affymetrix GeneChip 100 and 500 K SNP genotyping platforms were used to perform a large-scale population-based study of CNV frequency. We constructed a genomic map of 578 CNV regions, covering approximately 220 Mb (7.3%) of the human genome, identifying 183 previously unknown intervals. Copy number changes were observed to occur infrequently (<1%) in the majority (>93%) of these genomic regions, but encompass hundreds of genes and disease loci. This North American population-based map will be a useful resource for future genetic studies. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Modelling mass transfer and agitator performance in multiturbine fermentors

A methodology for mathematically analyzing agitator performance and mass transfer in large multiturbine production fermentors is presented. The application of this approach provides a method for determining axial dissolved oxygen profiles under conditions of known mass transfer rates as a function of agitation-aeration characteristics. A stagewise approach is used which divides the fermentor into a series of mixing cells. This allows for each turbine and mixing cell to be individually optimized. The model also permits the determination of the mass transfer coefficient for each turbine based upon limited dissolved oxygen data. The primary limitation of this approach rests in the limited data and correlations available for multiturbine systems. The structure of the modelling approach can serve as a basis for testing single turbine correlations and adapting them to multiturbine systems. The step-by-step details of the mathematical analysis are presented and interpreted. A series of computer simulations demonstrate the effect of typical fermentor operating variables on the axial dissolved oxygen profile. Further simulations demonstrate the effect of modifying agitator blade numbers on the dissolved oxygen profile and agitator power requirement.     

Secondary metabolites from the aerial parts of Salvia palaestina Bentham

Three sesterterpenes (1-3), one triterpene (4) and five diterpenes (5-9) were isolated from the aerial parts of Salvia palaestina Bentham (Lamiaceae), together with two sesquiterpenes, 10 known diterpenes, three triterpenes, and rosmarinic acid. Their structural elucidation was accomplished by extensive spectroscopic methods including 1D ((1)H, (13)C, (13)C DEPT, TOCSY, NOESY) and 2D NMR experiments (DQF-COSY, HSQC, HMBC, ROESY) as well as ESIMS analysis and chemical analysis.     

Inducer exclusion by glucose 6-phosphate in Escherichia coli

The main mechanism causing catabolite repression by glucose and other carbon sources transported by the phosphotransferase system (PTS) in Escherichia coli involves dephosphorylation of enzyme IIA^Glc as a result of transport and phosphorylation of PTS carbohydrates. Dephosphorylation of enzyme IIA^Glc leads to 'inducer exclusion': inhibition of transport of a number of non-PTS carbon sources (e.g. lactose, glycerol), and reduced adenylate cyclase activity. In this paper, we show that the non-PTS carbon source glucose 6-phosphate can also cause inducer exclusion. Glucose 6-phosphate was shown to cause inhibition of transport of lactose and the non-metabolizable lactose analogue methyl-β- D -thiogalactoside (TMG). Inhibition was absent in mutants that lacked enzyme IIA^Glc or were insensitive to inducer exclusion because enzyme IIA^Glc could not bind to the lactose carrier. Furthermore, we showed that glucose 6-phosphate caused dephosphorylation of enzyme IIA^Glc. In a mutant insensitive to enzyme IIA^Glc-mediated inducer exclusion, catabolite repression by glucose 6-phosphate in lactose-induced cells was much weaker than that in the wild-type strain, showing that inducer exclusion is the most important mechanism contributing to catabolite repression in lactose-induced cells. We discuss an expanded model of enzyme IIA^Glc-mediated catabolite repression which embodies repression by non- PTS carbon sources.     

Diminished proliferation of human immunodeficiency virus-specific CD4+ T cells is associated with diminished interleukin-2 (IL-2) production and is recovered by exogenous IL-2

Virus-specific CD4(+) T-cell function is thought to play a central role in induction and maintenance of effective CD8(+) T-cell responses in experimental animals or humans. However, the reasons that diminished proliferation of human immunodeficiency virus (HIV)-specific CD4(+) T cells is observed in the majority of infected patients and the role of these diminished responses in the loss of control of replication during the chronic phase of HIV infection remain incompletely understood. In a cohort of 15 patients that were selected for particularly strong HIV-specific CD4(+) T-cell responses, the effects of viremia on these responses were explored. Restriction of HIV replication was not observed during one to eight interruptions of antiretroviral therapy in the majority of patients (12 of 15). In each case, proliferative responses to HIV antigens were rapidly inhibited during viremia. The frequencies of cells that produce IFN-gamma in response to Gag, Pol, and Nef peptide pools were maintained during an interruption of therapy. In a subset of patients with elevated frequencies of interleukin-2 (IL-2)-producing cells, IL-2 production in response to HIV antigens was diminished during viremia. Addition of exogenous IL-2 was sufficient to rescue in vitro proliferation of DR0101 class II Gag or Pol tetramer(+) or total-Gag-specific CD4(+) T cells. These observations suggest that, during viremia, diminished in vitro proliferation of HIV-specific CD4(+) T cells is likely related to diminished IL-2 production. These results also suggest that relatively high frequencies of HIV-specific CD4(+) T cells persist in the peripheral blood during viremia, are not replicatively senescent, and proliferate when IL-2 is provided exogenously.