Autophagy protein Rubicon mediates phagocytic NADPH oxidase activation in response to microbial infection or TLR stimulation

Phagocytosis and autophagy are two important and related arms of the host's first-line defense against microbial invasion. Rubicon is a RUN domain containing cysteine-rich protein that functions as part of a Beclin-1-Vps34-containing autophagy complex. We report that Rubicon is also an essential, positive regulator of the NADPH oxidase complex. Upon microbial infection or Toll-like-receptor 2 (TLR2) activation, Rubicon interacts with the p22phox subunit of the NADPH oxidase complex, facilitating its phagosomal trafficking to induce a burst of reactive oxygen species (ROS) and inflammatory cytokines. Consequently, ectopic expression or depletion of Rubicon profoundly affected ROS, inflammatory cytokine production, and subsequent antimicrobial activity. Rubicon's actions in autophagy and in the NADPH oxidase complex are functionally and genetically separable, indicating that Rubicon functions in two ancient innate immune machineries, autophagy and phagocytosis, depending on the environmental stimulus. Rubicon may thus be pivotal to generating an optimal intracellular immune response against microbial infection.     

Vertical distribution of bacterial community is associated with the degree of soil organic matter decomposition in the active layer of moist acidic tundra

The increasing temperature in Arctic tundra deepens the active layer, which is the upper layer of permafrost soil that experiences repeated thawing and freezing. The increasing of soil temperature and the deepening of active layer seem to affect soil microbial communities. Therefore, information on soil microbial communities at various soil depths is essential to understand their potential responses to climate change in the active layer soil. We investigated the community structure of soil bacteria in the active layer from moist acidic tundra in Council, Alaska. We also interpreted their relationship with some relevant soil physicochemical characteristics along soil depth with a fine scale (5 cm depth interval). The bacterial community structure was found to change along soil depth. The relative abundances of Acidobacteria, Gammaproteobacteria, Planctomycetes, and candidate phylum WPS-2 rapidly decreased with soil depth, while those of Bacteroidetes, Chloroflexi, Gemmatimonadetes, and candidate AD3 rapidly increased. A structural shift was also found in the soil bacterial communities around 20 cm depth, where two organic (upper Oi and lower Oa) horizons are subdivided. The quality and the decomposition degree of organic matter might have influenced the bacterial community structure. Besides the organic matter quality, the vertical distribution of bacterial communities was also found to be related to soil pH and total phosphorus content. This study showed the vertical change of bacterial community in the active layer with a fine scale resolution and the possible influence of the quality of soil organic matter on shaping bacterial community structure.     

SD-RLK28 positively regulates pollen hydration on stigmas as a PCP-Bβ receptor in Arabidopsis thaliana

Pollen hydration on dry stigmas is strictly regulated by pollen–stigma interactions in Brassicaceae. Although several related molecular events have been described, the molecular mechanism underlying pollen hydration remains elusive. Multiple B-class pollen coat proteins(PCP-Bs) are involved in pollen hydration. Here, by analyzing the interactions of two PCP-Bs with three Arabidopsis thaliana stigmas strongly expressing S-domain receptor kinase(SD-RLK), we determined that SD-RLK28 directly intera...     

Increased abundance of the non-indigenous zooplanktivore, <Emphasis Type=Italic>Bythotrephes longimanus</Emphasis>, is strongly correlated with greater spring prey availability in Canadian Shield lakes

The non-indigenous zooplanktivore, Bythotrephes longimanus, is a large Palaearctic cladoceran that is spreading rapidly in the Great Lakes watershed in North America. As a voracious predator, Bythotrephes can reduce herbivorous cladoceran abundance and diversity; however, the variables that affect its abundance are not well understood. To determine what bottom-up factors are associated with the abundance and seasonal dynamics of established Bythotrephes populations, two Bythotrephes datasets from lakes in south-central Ontario, Canada, were analysed using multiple regression and multivariate analyses: a multi-lake dataset of nine lakes sampled in 2003 and a multi-year dataset of one of these lakes, Harp Lake, sampled from 1994–1998 and 2001–2004. Bottom-up variables tested were Secchi disk depth, epilimnetic temperature, cladoceran (prey) density, total phosphorus, dissolved organic carbon and Chlorophyll a, as well as maximum depth for the multi-lake dataset. In both analyses and datasets, springtime abundance of herbivorous cladocerans was consistently found to be a significant factor associated with Bythotrephes (June–September) abundance; Bythotrephes annual abundance was significantly and positively associated with mean May and June prey abundance, along with mean Secchi disk depth for the multi-lake dataset, and groups of lakes or years with similar Bythotrephes seasonal abundance patterns were predicted by June prey abundance. Additionally, prey availability was the dominant contributor towards changes in weekly Bythotrephes birth rates calculated for two of the study lakes. Our study suggests that prey availability influences Bythotrephes abundance, which provides evidence that Bythotrephes establishment success is affected by the abundance of its prey.     

The effect of calciums on molecular motions of proteinase K

The native serine protease proteinase K binds two calcium cations. It has been reported that Ca²⁺ removal decreased the enzyme’s thermal stability and to some extent the substrate affinity, but has discrepant effects on catalytic activity of the enzyme. Molecular dynamics simulations were performed on the Ca²⁺-bound and Ca²⁺-free proteases to investigate the mechanism by which the calciums affect the structural stability, molecular motions, and catalytic activity of proteinase K. Very similar structural properties were observed between these two forms of proteinase K during simulations; and several long-lived hydrogen bonds and salt bridges common to both forms of proteinase K were found to be crucial in maintaining the local conformations around these two Ca²⁺ sites. Although Ca²⁺ removal enhanced the overall flexibility of proteinase K, the flexibility in a limited number of segments surrounding the substrate-binding pockets decreased. The largest differences in the equilibrium structures of the two simulations indicate that, upon the removal of Ca²⁺, the large concerted motion originating from the Ca1 site can transmit to the substrate-binding regions but not to the catalytic triad residues. In conjunction with the large overlap of the essential subspaces between the two simulations, these results not only provide insight into the dynamics of the underlying molecular mechanism responsible for the unchanged enzymatic activity as well as the decreased thermal stability and substrate affinity of proteinase K upon Ca²⁺ removal, but also complement the experimentally determined structural and biochemical data.     

Equivalent potential of water for the electronic structure of glycine

First-principles, all-electron, ab initio calculations have been performed to construct an equivalent potential of water for the electronic structure of glycine (Gly) in solution. The calculation involved three steps. The first step was to search for the minimum-energy geometric structure of the Gly + nH₂O system. The second step was to calculate the electronic structure of Gly with the potential of water molecules via the self-consistent cluster-embedding method (SCCE), based on the result obtained in the first step. The last step was to calculate the electronic structure of Gly with the potential of dipoles after replacing the water molecules with dipoles. The results show that the occupied molecular orbitals of Gly are raised by about 0.0524 Ry on average due to the effect of water. The effect of water can be simulated well using the dipole potential. The equivalent potential obtained can be applied directly to electronic structure calculations of proteins in solution using the SCCE method.     

A Durable Alternative for Proton‐Exchange Membranes: Sulfonated Poly(Benzoxazole Thioether Sulfone)s

To develop a durable proton‐exchange membrane (PEM) for fuel‐cell applications, a series of sulfonated poly(benzoxazole thioether sulfone)s ( SPTESBOs) are designed and synthesized, with anticipated good dimensional stability (via acid–base cross linking), improved oxidative stability against free radicals (via incorporation of thioether groups), and enhanced inherent stability (via elimination of unstable end groups) of the backbone. The structures and the degree of sulfonation of the copolymers are characterized using Fourier‐transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy (¹H NMR and ¹⁹F NMR). The electrochemical stabilities of the monomers are examined using cyclic voltammetry in a typical three‐electrode cell configuration. The physicochemical properties of the membranes vital to fuel‐cell performance are also carefully evaluated under conditions relevant to fuel‐cell operation, including chemical and thermal stability, proton conductivity, solubility in different solvents, water uptake, and swelling ratio. The new membranes exhibit low dimensional change at 25°C to 90°C and excellent thermal stability up to 250°C. Upon elimination of unstable end groups, the co‐polymers display enhanced chemical resistance and oxidative stability in Fenton's test. Further, the SPTESBO‐HFB‐60 (HFB‐60=hexafluorobenzene, 60 mol% sulfone) membrane displays comparable fuel‐cell performance to that of an NRE 212 membrane at 80°C under fully humidified condition, suggesting that the new membranes have the potential to be more durable but less expensive for fuel‐cell applications.     

中国新归化种广布苋的分布及其与腋花苋的关系

本文报道了中国苋科苋属的一新记录归化植物——广布苋(Amaranthus graecizans L．)。该种植株常匍匐,叶片狭长椭圆形至线状披针形,有时线形或菱形卵形,长至少为宽的2.5倍,花被片3枚,近等长,与中国有分布的本属其他物种有所区别。该种原产于欧洲地中海地区、非洲北部至亚洲西部,归化于欧洲其他地区、东亚、澳大利亚、北美洲以及我国的河南、河北和山东等地区。该种易与苋属其他种类相混淆,因此其在我国的分布区可能被低估。此外,本文还对该种的种下等级以及该种的相似种进行了区分,并对该种下亚种Amaranthus graecizans subsp. thellungianus (Nevski) Gusev与国内文献记载的腋花苋(Amaranthus roxburghianus Kung)之间的关系作了说明与澄清。     

Signaling involved in pituitary adenylate cyclase-activating polypeptide-stimulated ADNP expression

Activity-dependent neurotrophic protein (ADNP) was discovered as a novel response gene for VIP and has neuroprotective potential. When the VIP paralog, PACAP38 was added to mouse neuron-glia co-cultures, it induced ADNP mRNA expression in a bimodal fashion at subpico- and nanomolar concentrations with greater response at subpicomolar level. The response was attenuated by a PAC1-R antagonist at both concentrations and by a VPAC1-R antagonist at nanomolar concentration only. An IP3/PLC inhibitor attenuated the response at both concentrations of PACAP38, but a MAPK inhibitor had no effect. A PKA inhibitor suppressed the response at nanomolar concentration only. These findings suggest that ADNP expression is mediated through multiple receptors and signaling pathways that are regulated by different concentrations of PACAP.     

ICU鲍曼不动杆菌感染的流行状况及耐药性分析

目的对ICU住院患者鲍曼不动杆菌感染的流行状况及耐药情况进行调查,为临床合理选用抗菌药物提供参考。方法对2012年7月至2013年12月ICU住院患者送检的693份各种临床标本进行病原菌的分离鉴定,对分离出的鲍曼不动杆菌采用K-B法做体外药敏试验。结果 693份临床标本共分离出110株鲍曼不动杆菌,其中多重耐药菌株有103株（93.6%）,感染的标本来源以痰液最为常见（86.4%）。鲍曼不动杆菌对常用抗菌药物耐药广泛,对氨苄西林、头孢唑啉100%耐药,对哌拉西林、头孢曲松、复方新诺明、氨曲南、环丙沙星、头孢吡肟、哌拉西林/他唑巴坦及庆大霉素等多种抗菌药物的耐药率大于80.0%。结论 ICU患者鲍曼不动杆菌感染多由多重耐药菌株引起,感染部位以下呼吸道为主,其对抗菌药物耐药情况相当严峻,加强耐药性监测及合理使用抗菌药物,对减少耐药菌株的产生具有重要意义。