重金属污染土壤植物修复中的微生物功能研究进展

综述了国内外在重金属污染土壤植物-微生物联合修复领域的研究报道,总结了近5年的研究实例。植物-微生物联合修复体系具有生物固定与生物去除土壤重金属的两种功能,根际微生物可以菌根、内生菌等方式与根系形成联合体,通过增强植物抗性和优化根际环境,促进根系发展,增强植物吸收和向上转运重金属的能力。建立植物-微生物联合修复体系,可充分发挥植物与微生物作用功能的优势,提高污染土壤的修复效率。增强植物修复体系中微生物功能的重点是深入研究根际微生物、根系和介质载体三者之间复合功能,结合污染土壤类型与植物群落配置的特点筛选扩繁高效菌种与菌群。     

蚂蚁筑巢对西双版纳热带森林土壤易氧化有机碳时空动态的影响

蚂蚁筑巢定居能够形成与巢穴周围显著不同的微生境和土壤养分环境,从而对土壤易氧化有机碳(EOC)产生重要影响.本研究以中国科学院西双版纳勐仑热带植物园白背桐群落为研究对象,比较蚂蚁巢地与非巢地土壤EOC时空分布特征,并分析蚂蚁筑巢引起土壤理化性质的改变对土壤EOC时空动态的影响.结果表明: 研究区蚁巢和非蚁巢地土壤EOC随月份均呈明显的单峰型变化规律,表现为6月>9月>3月>12月;土壤EOC沿土层呈逐渐降低的变化趋势,在0～5 cm土层,蚁巢土壤EOC显著大于非巢地,在5～10和10～15 cm土层的差异不显著.蚂蚁筑巢显著提高了土壤温度、土壤有机碳、土壤易氧化有机碳、土壤微生物生物量碳、全氮、硝态氮和水解氮含量,显著降低了土壤含水率和容重,但对铵态氮、pH值的影响不显著.土壤有机碳、土壤微生物生物量碳是调控蚁巢和非巢地土壤EOC时空变化的主要因子,土壤温度、含水率、全氮和硝态氮等土壤指标对土壤EOC的影响次之.蚂蚁筑巢主要通过改变微生境(土壤温度和水分)及土壤养分(主要是土壤有机碳和微生物生物量碳)的状况,进而调控热带森林土壤易氧化有机碳的时空动态.     

青藓科中国新记录种——短尖拟青藓

该文报道了短尖拟青藓［Sciuro-hypnum ornellanum (Molendo) Ignatov & Huttunen］在新疆阿尔泰山的分布,这是该种在中国的首次记录。详细介绍了拟青藓属［Sciuro-hypnum （Hampe） Hampe］的由来,讨论了短尖拟青藓的形态特征及其地理分布,对其与形态相近种进行了比较分析,并提供了中国拟青藓属分种检索表。该种的发现不仅为中国青藓科植物研究提供了新资料,同时也进一步佐证了中国新疆植物区系与俄罗斯、中亚及欧洲的密切联系。     

Phylogenetic analysis of the fecal flora of the wild pygmy loris

The bacterial diversity in fecal samples from the wild pygmy loris was examined with a 16S rDNA clone library and restriction fragment length polymorphism analysis. The clones were classified as Firmicutes (43.1%), Proteobacteria (34.5%), Actinobacteria (5.2%), and Bacteroidetes (17.2%). The 58 different kinds of 16S rDNA sequences were classified into 16 genera and 20 uncultured bacteria. According to phylogenetic analysis, the major genera within the Proteobacteria was Pseudomonas, comprising 13.79% of the analyzed clone sequences. Many of the isolated rDNA sequences did not correspond to known microorganisms, but had high homology to uncultured clones found in human feces. Am. J. Primatol. 72:699–706, 2010. © 2010 Wiley‐Liss, Inc.     

Comparison of pulmonary vascular response to endogenous nitric oxide inhibition in sheep and pigs living at 2,300 m

To compare the role of nitric oxide in an adaptive process to chronic hypoxia, we examined the effects of endogenous nitric oxide synthase inhibition on pulmonary vascular tone in conscious sheep and pigs living at high altitude. Unanesthetized male sheep (n=6) and pigs (n=5), born and residing in the highlands of Qinghai Province, China (2,300–3,000 m a.s.l.) were studied at that altitude. Pulmonary artery pressure (P_pa), pulmonary artery wedge pressure (P_cwp), and cardiac output (CO) were measured. Pulmonary vascular resistance (PVR) was calculated as (P_pa—P_cwp)/CO. Using a climatic chamber, hemodynamic measurements during exposures to atmospheric pressures corresponding to altitudes of 0, 2,300, and 4,500 m a.s.l. were performed with and without NO inhibition, using N^w-nitro-l-argine (NLA; 20 mg kg^–1), a potent stereospecific competitive inhibitor of nitric oxide synthase. P_pa and PVR at baseline (2,300 m) and during hypoxic exposure (4,500 m) were significantly higher in pigs than in sheep. After NLA administration, P_pa increased and CO decreased in both animals, resulting in significantly increased PVR at baseline and during hypoxic exposure. However, there were no significant differences in the percent increase in basal or hypoxic PVR after NLA administration between sheep and pigs. We conclude that augmented endogenous NO production could contribute to the regulation of pulmonary vascular tone at high altitude in sheep and pigs. However, it is unlikely that NO is responsible for the different pulmonary vascular tones between sheep and pigs at basal condition at moderately high altitude.Communicated by G. Heldmaier     

The ATP binding cassette transporter A1 contributes to the secretion of interleukin 1beta from macrophages but not from monocytes

Deficiency of ABCA1 causes high density lipoprotein deficiency and macrophage foam cell formation in Tangier disease. ABCA1 was also postulated to mediate the secretion of IL-1beta from monocytes and macrophages. We investigated the contribution of ABCA1 to IL-1beta secretion from human monocytes and macrophages of normal donors and Tangier disease patients. Neither an anti-ABCA1 antisense oligonucleotide nor ABCA1 deficiency interfered with LPS-induced secretion of IL-1beta from full blood or freshly isolated monocytes. By contrast, anti-ABCA1 antisense oligonucleotides decreased the LPS-induced secretion of IL-beta from macrophages by 30-50%. The secretion of the precursor pro-IL-1beta and TNFalpha was not inhibited. Compared to normal macrophages, LPS-stimulated Tangier disease macrophages secreted less IL-1beta relative to TNFalpha. Also the spontaneous secretion of IL-1beta by Tangier macrophages was lower than by control cells. We conclude that IL-1beta is secreted from monocytes by an ABCA1-independent pathway and from macrophages by ABCA1-dependent and -independent pathways.     

Phosphorylation of 338SSYY341 regulates specific interaction between Raf-1 and MEK1

The present study characterizes the interaction between the Raf-1 kinase domain and MEK1 and examines whether the magnitude of their interaction correlates to the ability of Raf to phosphorylate MEK1. Here we show that the minimal domain required for the Raf kinase activity starts from tryptophan 342. Maximal binding of the Raf kinase domain to MEK1 and its kinase activity are achieved upon phosphorylation of the region (338)SSYY(341) in response to 4beta-12-O-tetradecanoylphorbol-13-acetate (TPA), or mutation of Y340Y341 to aspartic acids. Conversely, the TPA-stimulated MEK binding and kinase activity are diminished when this region is deleted or Ser(338) and Ser(339) are mutated to alanines. We also show that the integrity of the Raf ATP-binding site is necessary for the interaction between Raf-1 and MEK1. Furthermore, two MEK-binding sites are identified; the first is localized between amino acids 325 and 349, and the second is within the region between amino acids 350 and 648. Separately, the binding of each site to MEK1 is weak, but in a cis context, they give rise to a much stronger association, which can be further stimulated by TPA. Finally, we find that tryptophan 342, which is conserved among the Raf family and other protein kinases, is essential for the Ser(338) phosphorylation of the full-length Raf and its binding to MEK1. Taken together, our results indicate that the phosphorylation of Ser(338) and Tyr(341) on Raf exerts an important effect on reconfiguring the two MEK-binding sites. As a result, these two sites coordinate to form a high affinity MEK-binding epitope, leading to a marked increase in Raf kinase activity.     

Spatial distribution and environmental risk assessment of heavy metals identified in soil of a decommissioned uranium mining area

Abstract

The spatial distribution of six heavy metals (Cd, As, Zn, Pb, Cr, and Cu) in the soil of a decommissioned uranium mining area was investigated and their potential environmental risk was assessed. Soil samples were collected along the main riversides enclosing the mining area. The heavy metal distribution was determined by geospatial interpolation. Pearson correlation coefficient and principal component analysis were used to locate the sources of pollution which are the mine ore as natural source, and dressing plants and tailing area from human activity. The results indicate that the average concentrations of As and Cd strongly exceed the recommended EQSS (Environmental Quality Standard for Soils of China) limits at all sampling sites, whereas Zn concentrations were found to be slightly over the limit only at sampling sites close to the mining area. The concentrations of Cr, Cu and Pb were all within the recommended limits. Environmental risk was assessed using the toxicity characteristic leaching procedure defining the degree to which extend the metal is released into the solution. High leaching rates were found only for Zn and Cd, suggesting that together with its high concentrations Cd is the most toxic metal around the mining area, followed by As.     

沿干旱梯度小叶锦鸡儿灌丛化对草本植物叶片矿质元素浓度及地上生物量累积的影响

草原灌丛化通过改变物种之间的相互作用深刻影响着群落的结构和功能。然而,当前有关灌木如何影响不同功能群草本植物对矿质元素吸收和累积的研究仍明显不足。在内蒙古草原沿干旱梯度选取了4个研究地点,对比分析了小叶锦鸡儿(Caragana microphylla)灌丛斑块内和斑块外群落中禾草和非禾草功能群植物叶中矿质元素浓度以及地上生物量生产的差异,旨在阐明干旱和灌木对群落草本植物叶元素累积的影响,揭示灌草间相互作用的元素利用特征及其随干旱梯度的变化。结果显示：1)随干旱加剧,灌丛斑块内的非禾草功能群植物地上生物量保持恒定,但叶中的K、Ca、Mg、Fe、Mn和Cu元素浓度显著增加(P<0.05)。该结果表明群落中的非禾草功能群植物通过提高叶中的矿质元素水平来抵御和适应干旱胁迫。2)随干旱加剧,灌丛对非禾草功能群植物地上生物量,叶中Ca、Fe、Cu和Zn,禾草功能群植物叶中的P的累积影响从负(RII<0)或中性(RII=0)转变为正效应(RII>0)。该结果与胁迫梯度假说相符,表明灌木对草本植物的促进效应随干旱胁迫加剧而增加。3)灌丛的“沃岛”效应是驱动灌木对草本植物元素累积正效应...