Functional profiling of the gut microbiomes in two different populations of the brown planthopper,Nilaparvata lugens

Previous studies have demonstrated that gut symbionts are involved in the detoxification metabolism of insect hosts, but the relationship between gut symbionts and host detoxification metabolism of the brown planthopper (Nilaparvata lugens, BPH) remains unclear. In the present study, an indoor population (NlIP) and a field population (NlFP) of the BPH were used to characterize the functional profiling of the gut microbiome based on 16S rDNA sequencing. The results show that the NlIP and NlFP strains of N. lugens had different symbiont compositions, and Proteobacteria, Actinobacteria, and Firmicutes were the dominate phyla, accounting for >75% of the total symbiont compositions. Additionally, the NlIP strain had more Pantoea and Stenotrophomonas, while the NlFP strain showed a higher Wolbachia, Actinobacteria, and Herbaspirillum relative abundance. Furthermore, functional content of the metagenome predicted by PICRUSt demonstrated no significant difference in metagenomic function between the NlIP and NlFP strains in the principal component analysis (PCA), and only three types of genes, namely, genes involved with metabolic diseases, poorly characterized genes, and genes involved in circulatory systems, were different between the strains based on KEGG pathway analysis, which also speculated that gut symbionts are not directly involved in the detoxification metabolism for insecticides in the BPH. These results will be helpful for further research into the mechanisms of gut symbionts involved in detoxification metabolism in the BPH.     

Tree Species Traits but Not Diversity Mitigate Stem Breakage in a Subtropical Forest following a Rare and Extreme Ice Storm

Future climates are likely to include extreme events, which in turn have great impacts on ecological systems. In this study, we investigated possible effects that could mitigate stem breakage caused by a rare and extreme ice storm in a Chinese subtropical forest across a gradient of forest diversity. We used Bayesian modeling to correct stem breakage for tree size and variance components analysis to quantify the influence of taxon, leaf and wood functional traits, and stand level properties on the probability of stem breakage. We show that the taxon explained four times more variance in individual stem breakage than did stand level properties; trees with higher specific leaf area (SLA) were less susceptible to breakage. However, a large part of the variation at the taxon scale remained unexplained, implying that unmeasured or undefined traits could be used to predict damage caused by ice storms. When aggregated at the plot level, functional diversity and wood density increased after the ice storm. We suggest that for the adaption of forest management to climate change, much can still be learned from looking at functional traits at the taxon level.     

Is Vitamin E Toxic to Neuron Cells?

Besides acting as potent free radical scavengers, tocopherols and tocotrienols have been known to have non-antioxidant properties such as the involvement of α-tocopherol (αT) in PKC pathway and the anti-cancer properties of γ-tocotrienol (γT3). This study aims to elucidate whether protective effects shown by αT and γT3 in H₂O₂-induced neuron cultures have anti-apoptotic or pro-apoptotic tendency toward the initiation of neuronal apoptosis. H₂O₂ is used to induce apoptosis in primary cerebellar neuron cultures which is attenuated by pretreatment of αT or γT3 at concentrations ≤10 μM. Similar to our previous work, γT3 was found to be neurotoxic at concentrations ≥100 μM, whereas αT showed no neurotoxicity. Cellular uptake of γT3 was higher than that of αT. Treating cells simultaneously with either γT3 or αT and with then H₂O₂ led to higher expression of Bax and Bcl-2 than in neurons exposed to H₂O₂ alone. Analysis of Bcl-2/Bax ratio as ‘survival index’ showed that both pretreatment of γT3 and αT followed by H₂O₂ increase the ‘survival index’ of Bcl-2/Bax ratio compared to H₂O₂-treated cells, while treatment of γT3 alone decrease the ratio compared to unchanged Bcl2/Bax ratio of similar treatment with αT alone. Similar treatment of γT3 decreased p53 expression and activates p38 MAPK phosphorylation, whereas αT did not alter its expression compared to H₂O₂-treated cells. Treating neurons with only γT3 or αT increased the expression of Bax, Bcl-2, p53, and p38 MAPK compared to control with γT3 exerting stronger expression for proteins involved than αT. In conclusion, low doses of γT3 and αT confer neuroprotection to H₂O₂-treated neurons via their antioxidant mechanism but γT3 has stronger pro-apoptosis tendency than αT by activating molecules involved in the neuronal apoptotic pathway in the absence of H₂O₂.     

Aliesterase activity and reproduction in Musca domestica: Effects of DDT and metepa

The chemosterilant metepa, administered orally and topically to adult M. domestica, was found to reduce aliesterase activity, to reduce the hatch of eggs, and when administered orally it also prolonged the pre-ovipositional period. Orally administered DDT had little effect on aliesterase but did reduce egg viability. Selection of a strain of M. domestica with diazinon, in an attempt to increase its resistance to diazinon, had the unexpected result of the flies becoming more susceptible but concomitantly their level of aliesterase was significantly increased. The aliesterase level of the immature stages of M. domestica is reported.

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Zusammenfassung Es wurde festgestellt, daß das Chemosterilisans Metepa bei oraler oder topischer Applikation bei erwachsenen Stubenfliegen die Aliesterase-Aktivität herabsetzt, die Schlüpfrate der Eier vermindert und bei oraler Anwendung auch die Präovipositionszeit verlängert. Oral verabreichtes DDT hat wenig Einfluß auf die Aliesterase, setzt aber die Lebensfähigkeit der Eier herab. Die Selektion einer Linie von Musca domestica durch Diazinon mit dem Ziel, ihre Resistenz gegen Diazinon zu erhöhen, hatte das unerwartete Ergebnis, daß die Fliegen empfindlicher wurden, zugleich aber ihr Aliesterase-Spiegel signifikant anstieg. Der Aliesterase-Spiegel der nicht erwachsenen Stubenfliegen-Stadien wird angegeben.

     

Non-Additive Effects of Water and Nitrogen Addition on Ecosystem Carbon Exchange in a Temperate Steppe

Changes in precipitation and nitrogen (N) deposition can influence ecosystem carbon (C) cycling and budget in terrestrial biomes, with consequent feedbacks to climate change. However, little is known about the main and interactive effects of water and N additions on net ecosystem C exchange (NEE). In a temperate steppe of northern China, a field-manipulated experiment was conducted to evaluate the responses of NEE and its components to improve N and water availability from 2005 to 2008. The results showed that both water and N additions stimulated gross ecosystem productivity (GEP), ecosystem respiration (ER), and NEE. Water addition increased GEP by 17%, ER by 24%, and NEE by 11% during the experimental period, whereas N addition increased GEP by 17%, ER by 16%, and NEE by 19%. The main effects of both water and N additions changed with time, with the strongest water stimulation in the dry year and a diminishing N stimulation over time. When water and N were added in combination, there were non-additive effects of water and N on ecosystem C fluxes, which could be explained by the changes in species composition and the shifts of limiting resources from belowground (water or N) to aboveground (light). The positive water and N additions effects indicate that increasing precipitation and N deposition in the future will favor C sequestration in the temperate steppe. The non-additive effects of water and N on ecosystem C fluxes suggest that multifactor experiments are better able to capture complex interactive processes, thus improving model simulations and projections.     

Purification and Partial Characterization of β-Glucosidase from Fresh Leaves of Tea Plants （Camellia sinensis （L.） O. Kuntze）

β-Glucosidases are important in the formation of floral tea aroma and the development of resistance to pathogens and herbivores in tea plants. A novel β-glucosidase was purified 117-fold to homogeneity,with a yield of 1.26%, from tea leaves by chilled acetone and ammonium sulfate precipitation, ion exchange chromatography (CM-Sephadex C-50) and fast protein liquid chromatography (FPLC; Superdex 75, Resource S). The enzyme was a monomeric protein with specific activity of 2.57 U/mg. The molecular mass of the enzyme was estimated to be about 41 kDa and 34 kDa by SDS-PAGE and FPLC gel filtration on Superdex 200, respectively. The enzyme showed optimum activity at 50℃ and was stable at temperatures lower than 40℃. It was active between pH 4.0 and pH 7.0, with an optimum activity at pH 5.5, and was fairly stable from pH 4.5 to pH 8.0. The enzyme showed maximum activity towards pNPG, low activity towards pNP-Galacto, and no activity towards pNP-Xylo.     

Nucleation Promoting Factors Regulate the Expression and Localization of Arp2/3 Complex during Meiosis of Mouse Oocytes

The actin nucleation factor Arp2/3 complex is a main regulator of actin assembly and is involved in multiple processes like cell migration and adhesion, endocytosis, and the establishment of cell polarity in mitosis. Our previous work showed that the Arp2/3 complex was involved in the actin-mediated mammalian oocyte asymmetric division. However, the regulatory mechanisms and signaling pathway of Arp2/3 complex in meiosis is still unclear. In the present work, we identified that the nucleation promoting factors (NPFs) JMY and WAVE2 were necessary for the expression and localization of Arp2/3 complex in mouse oocytes. RNAi of both caused the degradation of actin cap intensity, indicating the roles of NPFs in the formation of actin cap. Moreover, JMY and WAVE2 RNAi decreased the expression of ARP2, a key component of Arp2/3 complex. However, knock down of Arp2/3 complex by Arpc2 and Arpc3 siRNA microinjection did not affect the expression and localization of JMY and WAVE2. Our results indicate that the NPFs, JMY and WAVE2, are upstream regulators of Arp2/3 complex in mammalian oocyte asymmetric division.     

蛋白质错误折叠循环扩增及其在朊病毒蛋白检测中的应用研究进展

朊病毒蛋白（prion protein,PrP）是传染性海绵状脑病的病原体,其检测是该病诊断的重要依据。该文从原理、方法、影响因素和检测应用方面对蛋白质错误折叠循环扩增（protein mis-folding cyclic amplification,PMCA）这种朊病毒蛋白新型检测技术做了介绍,旨在为朊病毒蛋白的检测和发病机制研究提供理论参考。