Eucalypt leaf decomposition in an intermittent stream in south-eastern Australia

Eucalypt leaf packs were placed at two sites in an intermittent stream during summer to examine the hypothesis that terrestrially-exposed leaf litter accumulates a richer microbial flora than submerged leaves — a phenomenon observed in Canadian temporary vernal pools. This did not occur; during the experiment, microbial biomass (as ATP) rose steadily on submerged leaves but remained low on terrestrially-exposed leaves. Densities of most functional feeding groups on the submerged leaves increased with time. Scrapers appeared to be more important than shredders in eucalypt leaf breakdown at both sites.     

Factors affecting growth and nodulation ofHippophaë rhamnoides L. ssp.Rhamnoides in soils from two successional stages of dune formation

Summary To explain the decline of Hippopha? scrub in the vegetation succession in the dunes of The Netherlands, the growth and nodulation of Hippopha? plants grown in pots, using soil from an early stage (site AH) and a post-optimum stage (site HP), were investigated. In HP-soil nodulation, yield, and the nitrogen and phosphorus content of test plants were always lower and the number of necrotic nodules and the dry matter content were always higher than in AH-soil, even after inoculation with crushed nodules and the addition of a nutrient solution. Plants in HP-soil also had darker roots, less root hairs, a higher number of short lateral roots and a higher percentage of dead roots than those in AH-soil. These characteristics of adverse growth conditions disappeared upon ignition or gamma-irradiation of HP-soil. Possible explanations of these results are discussed. The degeneration of Hippopha? scrub cannot be ascribed to the age of the plants, the absence of sufficient infective endophyte particles or to abiotic factors such as unfavourable physical (particle size) or chemical soil conditions but is caused by biotic factors. No indications were obtained that plant-pathogenic fungi and bacteria are involved. HP-soil in contrast to AH-soil, however, contained large numbers of the nematodeLongidorus sp., a species known to cause root deformations. The conclusion was that this nematode is one of the biotic factors involved in the degeneration of the Hippopha? scrub. This degeneration is due to a restriction of the root system resulting in a low phosphate uptake, a low nodulation capacity and, as a consequence, a low nitrogen content. The results demonstrate that biotic soil factors are important in influencing succession in higher plant communities.     

Diethylpyrocarbonate—An effective agent for the sterilization of different types of nutrient media

A simple and convenient method has been tested for the steriltzation of nutrient media for long-term cultivation of plant cells. Diethylpyrocarbonate is suitable for this task in concentrations about 1000 mg l^-1 The cells cultivated for 15 subsequent passages on media treated by DPC had the same growth parameters, production pattern and ability to transform exogeneous organic compounds as did the controls. The method is suitable for the preparatian of both liquid and agar media, for stabilization of stock solutions and for sterilization of cultivation vessels and tubing.Abbreviations DPC diethylpyrocarbonate - medium MS nutrient medium according to Murashige and Skoog - NAA naphtaleneacetic acid     

SENP1-mediated NEMO de-SUMOylation inhibits intermittent hypoxia induced inflammatory response of microglia in vitro

Among the seven small ubiquitin-like modifier (SUMO)-specific proteases (SENPs), our previous work showed that SENP1 suppressed nuclear factor kappa B (NF-κB) activation and alleviates the inflammatory response in microglia. However, the mechanism is still largely unknown. In this study, western blot analysis and enzyme-linked immunosorbent assay were utilized for evaluating the extent of NF-κB activation and expression of proinflammatory cytokines. qPCR and western blot analysis were performed to detect SENP1 expression. Coimmunoprecipitation followed by western blot analysis was applied to measure the changes in SUMOylation of NF-κB essential modulator (NEMO) and P65 in microglia with or without overexpression of SENP1. As the results, we found that intermittent hypoxia (IH) triggered the activation of NF-κB and upregulated the expression levels of tumor necrosis factor-α and interleukin-6. Interestingly, our data indicated that the SUMOylation of NEMO was enhanced by IH while SUMOylation of P65 was not affected. Further, our data showed that overexpression of SENP1 could decrease the extent of NF-κB activation and inhibit the inflammatory response of microglia through regulating the SUMOylation of NEMO. Collectively, this study presents the first report of the SENP1-controlled de-SUMOylation process of NEMO and its critical role in regulating NF-κB activation and proinflammatory cytokines secretion in microglia cells. This study would benefit for clarifying the role of SENP1 in IH-induced activation of microglia, thus providing potential therapeutic targets for obstructive sleep apnea treatment.     

Intermittent Fasting Confers Protection in CNS Autoimmunity by Altering the Gut Microbiota

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Short-Term,Intermittent Fasting Induces Long-Lasting Gut Health and TOR-Independent Lifespan Extension

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Isolation of endophytic diazotrophic bacteria from wetland rice

Endophytic nitrogen-fixing bacteria are believed to contribute substantial amounts of N to certain gramineous crops. We have been interested to find (a) a diazotroph(s) in rice which can aggressively and stably persist and fix nitrogen in interior tissues and (b) unique rice-diazotrophic endophyte combinations. To achieve these objectives, it has been essential to find an efficient method to surface sterilize rice tissues. The method described here consists of exposing tissues to 1% Chloramine T for 15 min followed by shaking with glass beads. It has proven very efficient since (a) surface bacterial populations on the root and culm were found to be reduced by more than 90%, (b) the number of the internal colonizers was found to be significantly higher than the number of surface bacteria, and (c) colonization of root but not subepidermal tissue by gusA-marked Herbaspirillum seropedicae Z67 bacteria was found to be virtually eliminated. Nitrogen-fixing putative endophytic populations (MPN g dry wt) in the root (7.94 × 10) and culm (2.57 × 10) on field-grown IR72 plants grown in the absence of N fertilizer was found to be significantly higher near heading stage. The corresponding total putative endophyte populations in the tissues of 25 highly diverse genotypes of rice and their relatives was found to range from 10–10and 10–10, in the roots and culms, respectively. Generally, the resident bacteria were found to be non-diazotrophic, although in isolated cases diazotrophs were found, for example in the roots and culm of IR72 rice plants, or the culm of Zizaniopsis villanensis plants. The size of populations of diazotrophic bacteria in different rice genotypes was found to be 10–10 for the roots and 10–10 for the culms, respectively. The rice genera-related plants Potamophila pariffora and Rhynchoryza subulata showed the highest levels.