Screening and degradation performances of dominant strains in high-salinity landfill leachate

In order to enhance the removal efficiency of chemical oxygen demand (COD) in the high-salinity landfill leachate, the dominant strains were isolated from high-salinity landfill leachate. The dominant strains and bacteria consortium were screened for COD treatment potential using an aerobic COD concentration decrease test. Ten strains, TJ01–TJ10, were isolated, of which six strains TJ02, TJ03, TJ05, TJ06, TJ07, and TJ09 were found to have higher COD removal when the single bacteria were added, all more than 20%. The most effective combination was TJ06 + TJ09; the COD removal efficiency reached 45.57%. 16S rDNA gene sequence analysis revealed that TJ06 and TJ09 belonged to the genus Bacillus. The effects of the dominant bacteria consortium on the high-salinity landfill leachate varied with pH value and the volume fraction of leachate. The COD removal efficiencies maintained higher when the pH value was 6–8 and the volume fractions of leachate were less than 80%. The result also suggested that there is little effect on the growth of TJ06 and TJ09 when the range of Cl⁻ concentration is 0–30,000 mg/L.     

ROS-Mediated ABA Signaling

In plants, reactive oxygen species (ROS) are short-lived molecules produced through various cellular mechanisms in response to biotic and abiotic stimuli. ROS function as second messengers for hormone signaling, development, oxygen deprivation, programmed cell death, and plant–pathogen interactions. Recent research on ROS-mediated responses has produced stimulating findings such as the specific sources of ROS production, molecular elements that work in ROS-mediated signaling and homeostasis, and a ROS-regulated gene network (Neill et al., Curr Opin Plant Biol 5:388–395, 2002a; Apel and Hirt, Annu Rev Plant Biol 55:373–399, 2004; Mittler et al., Trends Plant Sci 9:490–498, 2004; Mori and Schroeder, Plant Physiol 135:702–708, 2004; Kwak et al., Plant Physiol 141:323–329, 2006; Torres et al., Plant Physiol 141:373–378, 2006; Miller et al., Physiol Plant 133:481–489, 2008). In this review, we highlight new discoveries in ROS-mediated abscisic acid (ABA) signaling. Drs. Daeshik Cho and June M. Kwak are the corresponding authors for this paper.     

Redox regulation of plant stem cell fate

Despite the importance of stem cells in plant and animal development, the common mechanisms of stem cell maintenance in both systems have remained elusive. Recently, the importance of hydrogen peroxide (H₂O₂) signaling in priming stem cell differentiation has been extensively studied in animals. Here, we show that different forms of reactive oxygen species (ROS) have antagonistic roles in plant stem cell regulation, which were established by distinct spatiotemporal patterns of ROS‐metabolizing enzymes. The superoxide anion () is markedly enriched in stem cells to activate WUSCHEL and maintain stemness, whereas H₂O₂ is more abundant in the differentiating peripheral zone to promote stem cell differentiation. Moreover, H₂O₂ negatively regulates biosynthesis in stem cells, and increasing H₂O₂ levels or scavenging leads to the termination of stem cells. Our results provide a mechanistic framework for ROS‐mediated control of plant stem cell fate and demonstrate that the balance between and H₂O₂ is key to stem cell maintenance and differentiation.     

Monoamine oxidases (MAO) in the pathogenesis of heart failure and ischemia/reperfusion injury

Recent evidence highlights monoamine oxidases (MAO) as another prominent source of oxidative stress. MAO are a class of enzymes located in the outer mitochondrial membrane, deputed to the oxidative breakdown of key neurotransmitters such as norepinephrine, epinephrine and dopamine, and in the process generate H₂O₂. All these monoamines are endowed with potent modulatory effects on myocardial function. Thus, when the heart is subjected to chronic neuro-hormonal and/or peripheral hemodynamic stress, the abundance of circulating/tissue monoamines can make MAO-derived H₂O₂ production particularly prominent. This is the case of acute cardiac damage due to ischemia/reperfusion injury or, on a more chronic stand, of the transition from compensated hypertrophy to overt ventricular dilation/pump failure. Here, we will first briefly discuss mitochondrial status and contribution to acute and chronic cardiac disorders. We will illustrate possible mechanisms by which MAO activity affects cardiac biology and function, along with a discussion as to their role as a prominent source of reactive oxygen species. Finally, we will speculate on why MAO inhibition might have a therapeutic value for treating cardiac affections of ischemic and non-ischemic origin. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.     

Investigation into the intracellular fates,speciation and mode of action of selenium-containing neuroprotective agents using XAS and XFM

Background

A variety of selenium compounds have been observed to provide protection against oxidative stress, presumably by mimicking the mechanism of action of the glutathione peroxidases. However, the selenium chemistry that underpins the action of these compounds has not been unequivocally established.

Production of 13C polyunsaturated fatty acids from the microalga Phaeodactylum tricornutum

An integrated process for the indoor production of ¹³C labelled PUFA from Phaeodactylum tricornutum is presented. The core of the process is a bubble column photobioreactor from which the exhaust gas from the reactor is returned to the culture by a low pressure compressor. To avoid accumulation of dissolved oxygen in the culture medium, the exhaust gas is bubbled through a sodium sulphite solution before returning it to the reactor. Carbon is removed from the medium before inoculating the alga, then labelled ¹³CO₂ is injected for pH control and carbon supply. The reactor has been operated in semicontinuous mode at a dilution rate of 0.01 h^–1, a biomass productivity of 0.1 g L^–1 d^–1 being obtained. Under this conditions both pH and dissolved oxygen were correctly controlled and the adequacy of the system for autotrophic production of labelled biomass was demonstrated. Analysis by GC-MS revealed that the fatty acids content of the biomass obtained was 10% d.wt., the content of eicosapentaenoic acid was 2.5% d.wt. All the fatty acids were labelled, more that 90% of the carbon present in these fatty acids was ¹³C. Element analysis of biomass and supernatant showed that 59.5% of injected carbon was assimilated into the biomass whereas 33% remained in the supernatant, and 7.5% remained undetected. Due to the high cost of ¹³CO₂ different strategies for the optimisation of labelled carbon use are proposed.     

Central Amazon Floodplain Forests: Root Adaptations to Prolonged Flooding

The floodplains of Central Amazonia represent a complex system of inundated river valleys and shallow lakes along the Solimões–Amazonas river, which is subjected to an annual flood-pulse lasting up to 10 months. Such flooding reaching an amplitude of about ten meters causes dramatic changes in the bioavailability of nutrients and oxygen levels and poses extreme constraints for plant survival and reproductivity. Tree species of inundation forests in Central Amazonia had to evolve adaptive mechanisms to both desiccation of soils and partial or full submergence. To adapt to flooded conditions, some trees overcome the flood period by dormancy accompanied by defoliation and formation of annual rings in the wood. Other species maintain metabolism and retain the foliage during the flooding, representing another adaptive mechanism to low oxygen availability. This investigation focused on the root physiology and morphology of six species typical of white-water inundation areas (várzea) led to a preliminary classification of adaptive strategies of trees inhabiting forest communities in floodplains of the Amazon basin.     

Decreased mitochondrial OGG1 expression is linked to mitochondrial defects and delayed hepatoma cell growth

Many solid tumor cells exhibit mitochondrial respiratory impairment; however, the mechanisms of such impairment in cancer development remain unclear. Here, we demonstrate that SNU human hepatoma cells with declined mitochondrial respiratory activity showed decreased expression of mitochondrial 8-oxoguanine DNA glycosylase/lyase (mtOGG1), a mitochondrial DNA repair enzyme; similar results were obtained with human hepatocellular carcinoma tissues. Among several OGG1-2 variants with a mitochondrial-targeting sequence (OGG1-2a, -2b, -2c, -2d, and -2e), OGG1-2a was the major mitochondrial isoform in all examined hepatoma cells. Interestingly, hepatoma cells with low mtOGG1 levels showed delayed cell growth and increased intracellular reactive oxygen species (ROS) levels. Knockdown of OGG1-2 isoforms in Chang-L cells, which have active mitochondrial respiration with high mtOGG1 levels, significantly decreased cellular respiration and cell growth, and increased intracellular ROS. Overexpression of OGG1-2a in SNU423 cells, which have low mtOGG1 levels, effectively recovered cellular respiration and cell growth activities, and decreased intracellular ROS. Taken together, our results suggest that mtOGG1 plays an important role in maintaining mitochondrial respiration, thereby contributing to cell growth of hepatoma cells.     

Drugs to cure avian influenza infection – multiple ways to prevent cell death

New treatments and new drugs for avian influenza virus (AIV) infection are developed continually, but there are still high mortality rates. The main reason may be that not all cell death pathways induced by AIV were blocked by the current therapies. In this review, drugs for AIV and associated acute respiratory distress syndrome (ARDS) are summarized. The roles of antioxidant (vitamin C) and multiple immunomodulators (such as Celecoxib, Mesalazine and Eritoran) are discussed. The clinical care of ARDS may result in ischemia reperfusion injury to poorly ventilated alveolar cells. Cyclosporin A should effectively inhibit this kind of damages and, therefore, may be the key drug for the survival of patients with virus-induced ARDS. Treatment with protease inhibitor Ulinastatin could also protect lysosome integrity after the infection. Through these analyses, a large drug combination is proposed, which may hypothetically greatly reduce the mortality rate.     

Oxygen‐dependent delayed fluorescence of protoporphyrin IX measured in the stomach and duodenum during upper gastrointestinal endoscopy

Protoporphyrin IX‐triplet state lifetime technique (PpIX‐TSLT) is a method used to measure oxygen (PO₂) in human cells. The aim of this study was to assess the technical feasibility and safety of measuring oxygen‐dependent delayed fluorescence of 5‐aminolevulinic acid (ALA)‐induced PpIX during upper gastrointestinal (GI) endoscopy. Endoscopic delayed fluorescence measurements were performed 4 hours after oral administration of ALA in healthy volunteers. The ALA dose administered was 0, 1, 5 or 20 mg/kg. Measurements were performed at three mucosal spots in the gastric antrum, duodenal bulb and descending duodenum with the catheter above the mucosa and while applying pressure to induce local ischemia and monitor mitochondrial respiration. During two endoscopies, measurements were performed both before and after intravenous administration of butylscopolamine. Delayed fluorescence measurements were successfully performed during all 10 upper GI endoscopies. ALA dose of 5 mg/kg showed adequate signal‐to‐noise ratio (SNR) values >20 without side effects. All pressure measurements showed significant prolongation of delayed fluorescence lifetime compared to measurements performed without pressure (P < .001). Measurements before and after administration of butylscopolamine did not differ significantly in the duodenal bulb and descending duodenum. Measurements of oxygen‐dependent delayed fluorescence of ALA‐induced PpIX in the GI tract during upper GI endoscopy are technically feasible and safe.