Sodium current of neurosecretory cells in the eyestalk from the shrimp Penaeus japonicus

The properties of the inward current of medulla terminalis-X-organ (MTXO) cells isolated from the Penaeus japonicus eyestalk were studied with the whole-cell clamp technique in the presence of Ca²⁺ and K⁺ channel blockers. The inward currents had a threshold at about −50 mV and peaked at −10 mV. The reversed potential (V_rev) was very close to V_Na, the theoretical Nernst equilibrium potential for Na⁺. V_rev followed V_Na when the external Na⁺ concentration was varied and the currents were entirely suppressed by 30 nM tetrodotoxin (TTX), indicating that it was carried by Na⁺. The smooth line of concentration-dependent inhibition of sodium currents by TTX represented the best fit with the Hill equation, yielding an IC₅₀ of 2.1 ± 0.1 nM. The values of the half-maximal activation voltage V_h were −20.6 ± 0.5 and −19.3 ± 0.5 mV, respectively, in the absence and presence of 2 nM TTX. TTX had no significant effect on the voltage dependence of steady-state activation and inactivation of I_Na. Taken together, the results suggest that the inward current recorded under our experimental conditions was carried by sodium ions flowing through fast voltage-dependent Na⁺ channels.     

Short-term dynamics of nutrients influenced by upwelling in a small oligotrophic coastal ecosystem, Gan Bay, in the northwest Philippines

We present a time-series analysis of nutrient and pCO2 (partial pressure of CO2) levels in an oligotrophic coastal ecosystem (Gan Bay), which was likely to be influenced by upwelled subsurface water. Gan Bay is off Currimao Harbor, in the northwest Philippines and is located at the boundary of the South China Sea (SCS). This 42-h time-series observation was conducted in December 2006. In addition to continuous observations of dissolved oxygen (DO) and pCO2, discrete samples were collected at a depth of 5 m every 3 h for measurements of nutrients, including soluble reactive phosphorus (SRP) and inorganic nitrogen (NO3 +NO2 ) in order to examine their dynamics and possible physical and biological controls. We observed remarkably large short-term variations in the surface water,spanning a 10-fold change for SRP (32–330 nM) and from <0.3 μM to 4.3 μM for NO3 +NO2 . DO also varied substantially from a lower end of 171 to 205 μM O2. Surface water pCO2 changed from an equilibrium stage with the atmosphere ( 386 μatm) to a stage where it was a significant source for the atmospheric CO2 (seawater pCO2 469 μatm). We found that the variation of nutrients was driven neither by tidal mixing nor by biological activities, as was suggested by the variations in the total bacterial abundance and chlorophyll a. Instead, our inverse T–S relationship suggested a two end-member mixing process during the observation period. The N:P ratio throughout the observation period was 13.2, which is characteristic of SCS subsurface and deep waters. Moreover, pCO2 was correlated inversely with the sea surface temperature. It is likely, therefore, that an upwelled subsurface cold water with high nutrients, low-temperature and high-pCO2 existed. It should be noted that this upwelled cold water did not appear to impact the entire observation period (approximately 35 h of 42 h), which might suggest an extremely dynamic nature for this upwelled cold water mass.     

纳米银对小麦秸秆还田土壤中酶活性及微生物群落功能多样性的影响

采用室内培养的方式,设置空白对照组（无添加,CK）、土壤＋小麦秸秆组（SW）、土壤+小麦秸秆+纳米银组（AgSW）,探究纳米银对秸秆还田农田土壤的呼吸作用,碳循环相关酶包括过氧化物酶、多酚氧化酶和纤维素酶的活性,微生物群落功能多样性的影响。结果显示：与CK组相比,添加小麦秸秆的SW组提升了土壤呼吸速率,使CO₂累计释放量增加了9.9%;与SW组相比,添加纳米银的AgSW组抑制了土壤呼吸作用,CO₂累计释放量减少36.8%,同时3种酶活性显著降低,过氧化物酶、多酚氧化酶和纤维素酶的活性可分别最高降低25.1%、27.1%和14.3%;微生物群落水平生理特征(CLPP)分析结果发现,纳米银显著降低了微孔板平均孔颜色变化率（与SW组相比下降了73.8%）和微生物多样性与丰富度。研究认为纳米银通过抑制土壤酶与微生物活性改变了土壤有机质分解的生态学过程,使微生物群落功能多样性降低。     

Experimental study on soil respiration of temperate grassland in China

Understanding of CO2 source and sink characteristics of terrestrial ecosystem is one of the most critical prob-lems at present, but till now, most studies concerning the natural terrestrial ecosystem carbon cycle are concentrated on the forest ecosystem. Not enough attention is paid to the natural grassland, especially to the temperate natural grassland, whose area is almost equal to that of tropical forest in the world. Little is known about the role of the grassland, which takes about 25% of…     

Estimation of soil respiration in a paddy ecosystem in the subtropical resion of China

Water vapor, energy exchange, and CO2 flux were measured continuously from 2003 to 2005 using the eddy covariance technique in a paddy ecosystem in the subtropical region of China. The CO2 fluxes at nighttime during fallow periods （from middle October to late April） were used to analyze the dynamics of soil respiration and its relationship with soil temperature, and to simulate the annual dynamics of soil respiration in paddy ecosystems. The variation of soil respiration showed a clear seasonal pattern. The soil respiration rates at night during the fallow periods were 52--398 mg· m^-2· h^-1, and exponentially correlated （P〈0.001） with soil temperatures at different depths of soil （5, 10, and 20 cm）, particularly the temperature measured at a depth of 5 cm. Based on the simulated exponential equations developed, annual average soil respiration rates and total soil respiration of paddy soil in the subtropical region of China were estimated to be 178.5--259.9 mg· m^-2· h^-1 and 1.56--2.28 kg· m^-2· a^-1, respectively. The simulation equations can be applied to evaluating soil respiration in paddy ecosystems during the rice-growing season.     

去除和添加凋落物对马尾松×红锥混交林土壤呼吸的影响

为探讨凋落物输入量改变对马尾松×红锥混交林碳排放的影响,以马尾松×红锥异龄混交林为研究对象,通过添加和去除凋落物人为地改变碳输入,研究凋落物处理方式对土壤呼吸的影响。结果表明:(1)去除凋落物可降低土壤湿度、提高土壤温度,而添加凋落物则提高土壤湿度、降低土壤温度。去除凋落物使土壤年均呼吸速率显著降低27.88%,而添加凋落物则使土壤年均呼吸速率显著增加34.02%。(2)去除凋落物能降低四季的土壤呼吸累积排放量,而添加凋落物则提高四季的土壤呼吸累积排放量。对照、去除和添加凋落物的土壤呼吸的年累积排放量(以C计)分别为(9.51±0.12) t·hm~(-2)、(6.88±0.21) t·hm~(-2)和(12.70±0.53) t·hm~(-2),可见去除凋落物使土壤呼吸年累积排放量降低27.66%,而添加凋落物使土壤呼吸年累积排放量提高33.54%。(3)不同凋落物处理方式下土壤呼吸速率与土壤温度均呈显著相关,土壤温度解释了土壤呼吸速率变异程度的74.26%～94.28%。去除凋落物增加了土壤呼吸温度敏感性系数Q10值,而添加凋落物则降低Q10值。凋落物处理方式对马尾松×红锥异龄混交林土壤呼吸产生了显著影响,证明凋落物对于改变森林生态系统土壤呼吸和碳循环具有重要作用。     

The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …     

电解锰废渣对玉米植株生长和重金属离子富集的影响

用原子吸收分光光度法分析了玉米根、茎、叶中重金属离子的含量.测定了锰废渣对盆栽玉米植株生长的影响,研究了电解锰废渣中重金属离子在植物体内的富集.结果表明：从株高来说,废渣种植>处理后废渣种植>土壤种植;铁离子的主要富集部位在根,最高富集量为2.347 3×10^-5,镉离子的主要富集部位在叶,最高富集量为3.57×10^-7,铬离子在根茎叶中的含量差不多,最高富集量为3.15×10^-7;废渣种植的玉米籽中重金属离子的含量最高,其中:Mn、Zn、Fe离子的含量非常高,分别达1.0×10^-5,1.6×10^-5,4.0×10^-6;Cr离子的含量高达3.7×10^-7;Cd离子的含量高达4.0×10^-8.     

Fluxes of carbon dioxide and methane from swamp and impact factors in Sanjiang Plain,China

Incomplete decomposition of organic matter results in the accumulation of the carbon and other nutriments in wetlands. The wetland ecosystem gains a large amount of carbon from atmosphere CO2 by photosynthesis, and it loses much of which back into the atmosphere as CO2 and CH4 emission through the decomposition and respiration. Climate change, such as global warming and reduction of precipitation could drive the wetlands from carbon sink to source[1,2]. Wetland plays an important role in car…     

Responses of woody plant root and xylem sap ATP to soil drying

The ATP in roots and xylem sap of two woody plant species, Platycladus orientalis and Acacia auriculiformis, subjected to rapid and slow soil drying has been determined employing firefly luciferase ATP assay method (sensitivity is at 10-12 mol ATP L-1). The ATP levels in the two species were 1.6 nmol·gDW-1 and 0.6 nmol·gDW-1 in roots, and 5.6 μmol·m-3 and 8 μmol ·m-3 in xylem sap, respectively. When plants of P. orientalis and A. auriculiformis were subjected to rapid soil drying, respectively, as soil water content (SWC) decreased from the normal level ( 0. 25 g ·gDW-1) to 0. 02 and 0. 06 g ·gDW-1, separately, plant water potential ( ) dropped to -4 and -3.2 MPa, differently, the ATP in roots decreased 99.7% and 42%, respectively . When the rapidly dried soil was watered for up to 6 d, SWC and were found to recover to their normal levels, but ATP content in roots of P. orientalis and A. auriculiformis recovered by 10% and 23%, respectively. When plants of P. orientalis and A. auriculiformis were subjected to slow soil drying, respectively, as SWC was found to decrease from the normal level to 0.1 and 0.13 g·gDW-1, separately, dropped to - 2.5 and - 2 MPa, differently, the ATP content in roots decreased 98% and 38%, respectively. When the slowly dried soil was watered for up to 8 d, ATP levels in roots of P. orientalis and A, auriculiformis recovered by 30% and 24%, respectively. However, ATP concentrations in xylem sap were not directly influenced by either SWC or . The plot dots of xylem sap ATP concentration versus root ATP content were found to be distributed diagonally. It is concluded that ATP in roots is more sensitive in response to SWC changes than that to and root-sourced ATP is a source of that in xylem sap. When plants are subjected to slow soil drying, the ATP levels in both root and xylem sap are higher than that to rapid soil drying.     

Effects of anions on the biosorption of microelement cations by macroalga <Emphasis Type="Italic">Enteromorpha prolifera</Emphasis> in single- and multi-metal systems

The results of research on the effects of anions on the biosorption of microelement cations by the edible marine macroalga Enteromorpha prolifera in singleand multi-metal systems are discussed in this paper. It was shown that the maximum biosorption capacity (qmax) in a single-metal system of Co(II) ions decreased in the following sequence: Cl- (46.0 mg g-1) > SO42- (42.8 mg g-1) > NO3- (41.9 mg g-1). In multi-metal systems, in which the ratios of Cl-, NO3-, and SO42- were 0:0:4, 1:1:2, 3:0:1, and 4:0:0, there were clear differences among the biosorption capacities. In all the examined systems (other than the 0:0:4 system), inhibition of the binding of microelement cations by the macroalga was observed. In all the systems, the highest value of qmax was obtained for Cu(II) cations; the value ranged from 31.9 mg g-1 in 0:0:4 (SO42- only) to 18.2 mg g-1 in 4:0:0 (Cl-only).     

Effect of exogenous lanthanum on accumulation of cadmium and its chemical form in Tomatoes

In the condition that soil is polluted by Cd(20 mg·L-1),two varieties of tomato(Lycopersicon esculintum Mill.)(plant high Cd-enriched variety(Yufen109)and plant low Cd-enriched variety(4641))treated with LaCl3 of different concentration(0,10 and 20mg·L-1)were determined for their effect on plant dry weight,anti-oxidase activity(CAT,SOD and POD),tomato fruit Cd chemical form and Cd accumulation.The results show that 10 mg?L-1LaCl3 can increase dry weight of plant at various positions and can reduce the concentration of Cd of different forms.Spraying with LaCl3(10,20 mg·L-1)can reduce Cd concentration in leaves,stems,roots and fruits of tomato plants with lowering rates of 13.7%-31.9%,9.5%-30.6%,10.8%-44.5%and 19.4%-37.0%,respectively.Suitable amount of lanthanum(10 mg·L-1 LaCl3)can increase yield of tomatoes,reduce Cd accumulation in the fruit.In the two tomato varieties,Lanthanum and Cadmium react interactively,expressing to be coexisting of both synergism and antagonistic.     

Characteristics of lateral heterogeneities with thermal and chemical origins in the pyrolitic lower mantle

The relative changes between shear and compressional velocities (R_SP = ∂ ln V_S/∂ ln V_P), bulk sound and shear velocities (R_CS = ∂ ln V_C/∂ ln V_S), and density versus shear wave velocity (R_ρS = ∂ ln ρ/∂ ln V_S) in response to thermal and chemical variations were investigated for the pyrolitic lower mantle. For heterogeneities with thermal origins, R_SP increases from 1.7 to 2.0 together with R_ρS decreasing from 0.4 to 0.2 and R_CS = ∼0.27 from the top to the bottom of the lower mantle. In comparison, chemical variations (bulk iron or silica contents) are characterized by R_SP < 1.5 and R_CS > 0.5 at lower mantle depths. Negative values of R_ρS and R_CS are indicative of chemical anomalies in the lower mantle, but a combination of thermal and chemical heterogeneities may be required to produce velocity and density anomalies at the magnitudes observed in seismic data. Further refinement of these characteristics requires data on the higher order pressure and temperature derivatives of the elastic moduli of the constituent phases.     

一种直接用于PCR分析的风沙土微生物总DNA提取方法

以风沙土为材料,直接提取土壤微生物DNA.采用SDS—溶菌酶—CTAB—蛋白酶K和液氮反复冻融法裂解细胞得到DNA粗提液,以PEG对其纯化.结果表明,SDS—溶菌酶—CTAB—蛋白酶K和液氮反复冻融法裂解细胞可获得大片段的DNA,提高DNA产率.每克干土的DNA提取量为0.586～1.311μg.所提DNA片段在23Kb以上.PEG可有助于去除DNA中腐植酸,DNA不作回收纯化即可作为模板进行16SrDNAPCR扩增.SDS—溶菌酶—CTAB—蛋白酶K和液氮反复冻融裂解细胞、PEG纯化DNA的方法组合是一种简便的适合风沙土微生物总DNA的提取方法.     

湘西地区不同居群箭叶淫羊藿叶片的脂质过氧化

对湘西地区凤凰、永顺、龙山3个不同居群的箭叶淫羊藿叶片的超氧阴离子自由基（·O₂）的产生速率和丙二醛（MDA）的含量进行测定.结果表明：永顺的箭叶淫羊藿的超氧阴离子自由基的产生速率最大,为(0.059　1±0.003　3) μmol·min^-1·g^-1,而龙山的箭叶淫羊藿的超氧阴离子自由基的产生速率最小,为(0.053　0±0.000　9) μmol·min^-1·g^-1;在3个不同居群的箭叶淫羊藿叶片的MDA的含量中,永顺的箭叶淫羊藿的含量最高,为(0.014 9±0.001 4) nmol·g^-1,而龙山的箭叶淫羊藿的含量最低,为(0.007　5±0.001　4) nmol·g^-1.     

Correction

Correction for "Physical and numerical modeling of biomimetic approaches of natural hydrophobic surfaces", by     

毒死蜱降解菌CD7的筛选与植物根际促生菌JD37的联合应用

筛得一株毒死蜱降解菌CD7,联合植物根际促生菌JD37,研制了一种能修复土壤的农药污染,同时促进植物生长的复合型土壤改良剂.实验结果显示:将CD7和JD37发酵液按体积比1∶1使用,可以促进植物生长,并在25 d内降解土壤中约66.43%的毒死蜱.在载体量相同情况下,蚯蚓粪比滑石粉吸附更多混合菌株.在室温贮藏一个月,活菌数为4.81×10~7CFU/g;制备的复合改良剂与土壤按质量比1∶1使用时,能促进植物生长、提升土壤酶活性、增加土壤中微生物的数量.     

石灰和聚丙烯酰胺对植烟酸性土壤钾、磷吸附解析和迁移的影响

通过吸附-解析试验和淋溶试验,研究了石灰和聚丙烯酰胺(PAM)对植烟酸性土壤钾、磷的吸附、解析和迁移的影响.结果表明:石灰和石灰+PAM处理能增加植烟酸性土壤对磷、钾的吸附量,其中以0.45%石灰+0.1%PAM处理的土壤吸附量最高,但当PAM用量增加时,吸附量下降;加入适量石灰和PAM后土壤对磷吸附强度降低,解析率升高;对钾而言,单纯加入石灰后吸附强度降低,解析率升高,而加入石灰+PAM后吸附强度又加大,但随PAM用量增高,吸附强度下降,解析率也出现先降低后升高的趋势.在植烟酸性土壤中施加0.45%石灰+0.1%PAM能有效缓解磷、钾向土层下迁移的趋势.     

沈阳市交通生态足迹的实证研究

介绍了城市交通生态足迹的模型和方法,并以沈阳市为例对城市交通生态足迹、生态效率做了定量计算与分析.结果表明:沈阳市2004年交通生态足迹为35×104hm2,其中,能源消费间接用地占99%,而道路和场站直接用地仅占1%;从生态足迹构成看,小轿车和出租车生态足迹较高,分别为18.5×104hm2,5.61×104hm2,占交通总足迹的比例分别为53%,16%;从城市交通生态效率看,公共汽车最高,为3.06×104人次.hm-2,小轿车最低,为0.12×104人次.hm-2;从城市交通生态足迹强度看,小轿车最高,为8.38×10-4hm2.人次-1,公共汽车最低,为0.33×10-4hm2.人次-...     

A new estimate of global soil respiration from 1970 to 2008

Soil respiration(Rs)is one of the key processes that underline our understanding of carbon cycle in terrestrial ecosystems.Great uncertainty remains in the previous global Rs estimates with a difference of 70 Pg C a 1between the highest and lowest estimates.Thus,the present study aimed to estimate the global annual Rs and investigate the interannual and spatial variability in global annual Rs using a semi-mechanistic,empirically-based model which included climatic factors(temperature and precipitation)and topsoil(0–20 cm)organic carbon storage.About 657 published studies of annual Rs from 147 measurement sites were included in this meta-analysis.The global data sets from 1970 to 2008 on climate,surface air temperature,and soil properties were collected.The Monte Carlo method was used to propagate the simulation errors to global Rs.The results indicated that the mean annual global Rs was 94.4 Pg C a 1,increasing at roughly 0.04 Pg C a 1(~0.04%a 1)from 1970 to 2008.The Rs rate increased from colder,drier and less soil carbon-rich regions to warmer,moister and more carbon-rich regions.Highest Rs rates appeared in the tropical forest,while the lowest ones were in polar and desert regions.The annual Rs correlated directly with global temperature anomalies,suggesting that the interannual variability in temperature was responsible for the interannual variations in predicted global Rs.The global Rs increased from high-latitude zones to low-latitude zones.Further studies are recommended to explore the relationship between soil respiration and vegetation characters.