Besprechungen

Ohne Zusammenfassung     

Die Wirkung der α-Bestrahlung auf Protoplasma und Chloroplasten

Ohne Zusammenfassung     

CD14 C-159T and Toll-Like Receptor 4 Asp299Gly Polymorphisms in Surviving Meningococcal Disease Patients

Background

Carriage of Neisseria meningitidis occurs approximately in 10% of the population, onset of invasive meningococcal disease (IMD) cannot be predicted and differs between ages. It remains unclear, which host factors determine invasion of the bloodstream by the bacteria. Innate immunity has a very important role in the first recognition of invading pathogens. The functional single nucleotide polymorphisms (SNPs) CD14 C-159T and toll-like receptor 4 (TLR4) Asp299Gly have been associated with the risk of gram-negative infections. However, their role in development of IMD still remains unclear. Our aim was to investigate the influence of CD14 C-159T and TLR4 Asp299Gly polymorphisms on the risk of IMD.

Methodology/Principal Findings

It was a retrospective case control study. Surviving Austrian meningococcal disease patients were enrolled by sending buccal swabs for DNA analysis. 185 cases with a proven meningococcal infection and 770 healthy controls were enrolled. In surviving meningococcal disease patients DNA analysis of CD14 C-159T and TLR 4 Asp299Gly polymorphisms was performed, as they are part of the innate immune response to bacterial determinants. CD14 C-159T and TLR4 Asp299Gly SNPs were not significantly associated with the presence of IMD when compared to healthy controls. The odds ratio for CD14 C-159T SNP was 1.14 (95% confidence interval (CI) 0.91–1.43; p = 0.266). In TLR4 Asp 299 Gly SNP the odds ratio was 0.78 (CI 0.47–1.43; p = 0.359).

Conclusion/Significance

We could not observe a significant influence of CD14 C-159T and TLR4 Asp299Gly polymorphisms on the risk of developing IMD in surviving meningococcal disease patients. To our knowledge, this is the first study investigating the influence of the CD14 C-159T SNP on the susceptibility to IMD.     

1,3-Propanediol formation with product-tolerant mutants of Clostridium butyricum DSM 5431 in continuous culture: productivity, carbon and electron flow

Glycerol fermentation and product formation of two product-tolerant mutants of Clostridium butyricum DSM 5431 were investigated in continuous culture at increasing glycerol feed concentrations. Under conditions of glycerol excess (above 55 g l⁻¹ at D = 0·15 h⁻¹), the mutants maintained a constant level of glycerol consumption and product formation, whereas the parent strain exhibited a substantial decrease in substrate conversion, 1,3-propanediol and butyrate formation, and an increase in acetate formation. The activities of the glycerol dehydrogenase, the glycerol dehydratase and the 1,3-propanediol dehydrogenase showed only slight changes with glycerol concentrations in the mutants, but dropped markedly at high concentrations in the wild type. Intracellular concentrations of NADH, NAD ⁺ and acetyl-CoA remained at a relatively constant level in the mutants, but increased sharply with the wild type strain. The NADH content was always higher than the NAD ⁺ content in the mutants as well as in the wild type.     

Optogenetic delivery of trophic signals in a genetic model of Parkinson’s disease

Optogenetics has been harnessed to shed new mechanistic light on current and future therapeutic strategies. This has been to date achieved by the regulation of ion flow and electrical signals in neuronal cells and neural circuits that are known to be affected by disease. In contrast, the optogenetic delivery of trophic biochemical signals, which support cell survival and are implicated in degenerative disorders, has never been demonstrated in an animal model of disease. Here, we reengineered the human and Drosophila melanogaster REarranged during Transfection (hRET and dRET) receptors to be activated by light, creating one-component optogenetic tools termed Opto-hRET and Opto-dRET. Upon blue light stimulation, these receptors robustly induced the MAPK/ERK proliferative signaling pathway in cultured cells. In PINK1^B9 flies that exhibit loss of PTEN-induced putative kinase 1 (PINK1), a kinase associated with familial Parkinson’s disease (PD), light activation of Opto-dRET suppressed mitochondrial defects, tissue degeneration and behavioral deficits. In human cells with PINK1 loss-of-function, mitochondrial fragmentation was rescued using Opto-dRET via the PI3K/NF-кB pathway. Our results demonstrate that a light-activated receptor can ameliorate disease hallmarks in a genetic model of PD. The optogenetic delivery of trophic signals is cell type-specific and reversible and thus has the potential to inspire novel strategies towards a spatio-temporal regulation of tissue repair.     

Fermentation of glycerol to 1,3-propanediol: use of cosubstrates

Three fermentable substances, glucose, 1,2-ethanediol and 1,2-propanediol were checked as cosubstrates for the fermentation of glycerol by Clostridium butyricum and Citrobacter freundii with the aim of achieving a complete conversion of glycerol to 1,3-propanediol. Glucose was fermented by C. butyricum mainly to acetate, CO₂ and reducing equivalents in the presence of glycerol and contributed markedly to the 1,3-propanediol yield. However, because of relatively slow growth on glucose, complete conversion was not achieved. If the two glycols were used as cosubstrates for glycerol fermentation, the 1,3-propanediol yield did not increase but dimished considerably, as they were converted to more reduced products, i.e. alcohols instead of acids. From 1,2-propanediol 2-propanol was formed in addition to 1-propanol. The ratio of the propanols was dependent on the culture conditions.     

Kinetic, dynamic, and pathway studies of glycerol metabolism by Klebsiella pneumoniae in anaerobic continuous culture: I. The phenomena and characterization of oscillation and hysteresis

Oscillation and hysteresis phenomena are observed in the anaerobic continuous fermentation of glycerol by Klebsiella pneumoniae in long-term cultivations under a variety of conditions. In this work, the conditions for the occurrence of these phenomena are reported and the patterns of cell growth and metabolism under oscillation are characterized. During an oscillation period, the formation rates of CO(2), H(2), and formate and the consumption rate of alkali periodically pass values of maxima and minima, the latter being close to zero. The formation of biomass and fermentation products such as 1,3-propanediol, acetate, and ethanol also undergo periodic changes which shift maxima and minima. Sustained oscillation occurs only under conditions of substrate excess within a distinct regime. At pH 7.0, it is only found at dilution rates above 0.15 h(-1) under the experimental conditions. At lower pH values, oscillations are more likely to happen, even at a relatively low dilution rate and low substrate excess. Whereas the amplitude of oscillations at pH 7.0 depends on both the dilution rate and the residual glycerol concentration (C(Glyc)) the interval of oscillations appears to be only a function of C(Glyc). An increase of C(Glyc) in culture damps the oscillation and leads to its disappearance at C(Glyc) = 1100 to 1200 mmol/L (pH 7.0). The operation mode was also found to be an important parameter in determining the stability and actual state of the culture, resulting in hysteresis under certain conditions, particularly at low pH values. Generally, a large perturbation of cultivation conditions tends to cause oscillation and hysteresis. The results unambiguously demonstrate that the oscillation and hysteresis phenomena shown in this work are bound to genuine metabolic fluctuations of the microorganism. They reveal several differences and new features compared with those reported in the literature and cannot be readily explained by the mechanisms known so far. (c) 1996 John Wiley & Sons, Inc.     

Zum Wasserhaushalt vonTillandsia recurvata L. undTillandsia usneoides L. auf Puerto Rico

Ohne ZusammenfassungHerrn Prof. Dr. A. Pisek (Innsbruck) zum 70. Geburtstage gewidmet.