Plants,microorganisms, and soil temperatures contribute to a decrease in methane fluxes on a drained Arctic floodplain

As surface temperatures are expected to rise in the future, ice‐rich permafrost may thaw, altering soil topography and hydrology and creating a mosaic of wet and dry soil surfaces in the Arctic. Arctic wetlands are large sources of CH₄, and investigating effects of soil hydrology on CH₄ fluxes is of great importance for predicting ecosystem feedback in response to climate change. In this study, we investigate how a decade‐long drying manipulation on an Arctic floodplain influences CH₄‐associated microorganisms, soil thermal regimes, and plant communities. Moreover, we examine how these drainage‐induced changes may then modify CH₄ fluxes in the growing and nongrowing seasons. This study shows that drainage substantially lowered the abundance of methanogens along with methanotrophic bacteria, which may have reduced CH₄ cycling. Soil temperatures of the drained areas were lower in deep, anoxic soil layers (below 30 cm), but higher in oxic topsoil layers (0–15 cm) compared to the control wet areas. This pattern of soil temperatures may have reduced the rates of methanogenesis while elevating those of CH₄ oxidation, thereby decreasing net CH₄ fluxes. The abundance of Eriophorum angustifolium, an aerenchymatous plant species, diminished significantly in the drained areas. Due to this decrease, a higher fraction of CH₄ was alternatively emitted to the atmosphere by diffusion, possibly increasing the potential for CH₄ oxidation and leading to a decrease in net CH₄ fluxes compared to a control site. Drainage lowered CH₄ fluxes by a factor of 20 during the growing season, with postdrainage changes in microbial communities, soil temperatures, and plant communities also contributing to this reduction. In contrast, we observed CH₄ emissions increased by 10% in the drained areas during the nongrowing season, although this difference was insignificant given the small magnitudes of fluxes. This study showed that long‐term drainage considerably reduced CH₄ fluxes through modified ecosystem properties.     

两种苹果蠹蛾性引诱剂诱捕器诱捕效率比较及地面植被的影响

在甘肃省高台县通过对三角胶粘式和水盆式这2种类型苹果蠹蛾Cydia pomonella(L.)诱捕器的田间比较研究。结果显示,二者在诱捕效率上存在的明显差异。在苹果蠹蛾密度较低的条件下,三角胶粘式诱捕器平均日诱捕量为2.50只,比水盆式诱捕器高出近2.84倍,最早监测到成虫的时间也比水盆式诱捕器提前3~4d,因此,三角胶粘式诱捕器具有更高的监测效率。结果还显示地面植被的遮盖极大地降低诱捕器的诱捕效果,严重时会使诱捕器对密度较低的苹果蠹蛾种群的监测功能丧失。     

Hydrolase-catalyzed Michael addition of 1,3-dicarbonyl compounds to α,β-unsaturated compounds in organic solvent

A novel strategy to perform Michael additions between 1,3-dicarbonyl compounds and α,β-unsaturated compounds was developed by the catalysis of hydrolase. We found that 11 hydrolase could catalyze the enzymatic Michael addition reaction to form the carbon–carbon bond. In 2-methyl-2-butanol d-aminoacylase showed high Michael addition activity. The influence of substrate and Michael acceptor structure on Michael addition was evaluated systematically. Some control experiments demonstrated that the active site of d-aminoacylase was responsible for the enzymatic Michael addition reaction. This novel Michael addition activity of hydrolase is of practical significance in expanding the application of enzymes and in the evolution of new biocatalysts.     

鞘内联合给予米诺环素和IL-6的中和抗体对脊神经结扎模型所引起的热痛敏的镇痛作用

目的:研究鞘内联合给予米诺环素和IL-6的中和抗体在大鼠脊神经结扎(spinal nerve ligation,SNL)模型所引起的神经病理性痛中的镇痛作用.方法:建立大鼠SNL模型,分别在手术前和手术后鞘内给予米诺环素100 μg、在手术后鞘内给予IL-6的中和抗体0.03 μg、手术后鞘内联合给予两种药物,观察给药3天各组大鼠热刺激的缩足反应潜伏期(paw withdrawal latencies,PWL).结果:①SNL手术前后给予米诺环素都可以提高大鼠的PWL(P＜0.05),但SNL手术前给药对大鼠PWL的提升明显高于手术后给药(P＜0.05).②手术后给予IL-6的中和抗体可以有效提升SNL组的PWL(P＜0.05),但是还是比给予生理盐水的假手术组大鼠的PWL明显减少(P＜0.05).③手术后联合给予两种药物可以明显逆转SNL组的PWL(P＜0.05).④联合给药对大鼠PWL的提高明显高于SNL手术后给予米诺环素组和给予IL-6的中和抗体组(P＜0.05),但与手术前给予米诺环素组的PWL相比无明显差异(P＞0.05).结论:鞘内联合给予米诺环素和IL-6的中和抗体对SNL引起的神经病理性痛有明显的镇痛作用.     

Oxytocin is expressed by both intrinsic sensory and secretomotor neurons in the enteric nervous system of guinea pig

Single- and double-immunostaining techniques were used systematically to study the distribution pattern and neurochemical density of oxytocin-immunoreactive (-ir) neurons in the digestive tract of the guinea pig. Oxytocin immunoreactivity was distributed widely in the guinea pig gastrointestinal tract; 3%, 13%, 17%, 15%, and 10% of ganglion neurons were immunoreactive for oxytocin in the myenteric plexuses of the gastric corpus, jejunum, ileum, proximal colon, and distal colon, respectively, and 36%, 40%, 52%, and 56% of ganglion neurons were immunoreactive for oxytocin in the submucosal plexuses of the jejunum, ileum, proximal colon, and distal colon, respectively. In the myenteric plexus, oxytocin was expressed exclusively in the intrinsic enteric afferent neurons, as identified by calbindin 28 K. In the submucosal plexuses, oxytocin was expressed in non-cholinergic secretomotor neurons, as identified by vasoactive intestinal polypeptide. Oxytocin-ir nerve fibers in the inner circular muscle layer possibly arose from the myenteric oxytocin-ir neurons, and oxytocin-ir nerve fibers in the mucosa possibly arose from both the myenteric and submucosal oxytocin-ir neurons. Thus, oxytocin in the digestive tract might be involved in gastrointestinal tract motility mainly via the regulation of the inner circular muscle and the balance of the absorption and secretion of water and electrolytes.     

Tracing the transition of methicillin resistance in sub-populations of Staphylococcus aureus, using SELDI-TOF Mass Spectrometry and Artificial Neural Network Analysis

Strains (n = 99) of Staphylococcus aureus isolated from a large number of clinical sources and tested for methicillin sensitivity were analysed by MALDI-TOF-MS using the Weak Cation Exchange (CM10) ProteinChip Array (designated SELDI-TOF-MS). The profile data generated was analysed using Artificial Neural Network (ANN) Analysis modelling techniques. Seven key ions identified by the ANNs that were predictive of MRSA and MSSA were validated by incorporation into a model. This model exhibited an area under the ROC curve value of 0.9147 indicating the potential application of this approach for rapidly characterising MRSA and MSSA isolates. Nearly all strains (n = 97) were correctly assigned to the correct group, with only two aberrant MSSA strains being misclassified. However, approximately 21% of the strains appeared to be in a process of transition as resistance to methicillin was being acquired.     

Differential mitochondrial calcium responses in different cell types detected with a mitochondrial calcium fluorescent indicator, mito-GCaMP2

Mitochondrial calcium plays a crucial role in mitochondrial metabolism, cell calcium handling, and cell death. However, some mechanisms concerning mitochondrial calcium regulation are still unknown, especially how mitochondrial calcium couples with cytosolic calcium. In this work, we constructed a novel mitochondrial calcium fluorescent indicator (mito-GCaMP2) by genetic manipulation. Mito-GCaMP2 was imported into mitochondria with high efficiency and the fluorescent signals co-localized with that of tetramethyl rhodamine methyl ester, a mitochondrial membrane potential indicator. The mitochondrial inhibitors specifically decreased the signals of mito-GCaMP2. The apparent K(d) of mito-GCaMP2 was 195.0 nmol/L at pH 8.0 in adult rat cardiomyocytes. Furthermore, we observed that mito-GCaMP2 preferred the alkaline pH surrounding of mitochondria. In HeLa cells, we found that mitochondrial calcium ([Ca(2+)](mito)) responded to the changes of cytosolic calcium ([Ca(2+)](cyto)) induced by histamine or thapasigargin. Moreover, external Ca(2+) (100 μmol/L) directly induced an increase of [Ca(2+)](mito) in permeabilized HeLa cells. However, in rat cardiomyocytes [Ca(2+)](mito) did not respond to cytosolic calcium transients stimulated by electric pacing or caffeine. In permeabilized cardiomyocytes, 600 nmol/L free Ca(2+) repeatedly increased the fluorescent signals of mito-GCaMP2, which excluded the possibility that mito-GCaMP2 lost its function in cardiomyocytes mitochondria. These results showed that the response of mitochondrial calcium is diverse in different cell lineages and suggested that mitochondria in cardiomyocytes may have a special defense mechanism to control calcium flux.     

秸秆带状覆盖对半干旱雨养区冬小麦田地温和产量的影响

为了明确秸秆带状覆盖对西北半干旱雨养区冬小麦田地温和产量形成的影响,于2013-2015年连续进行2年定位试验,设不覆盖露地(CK)、全膜覆土穴播(PM)、秸秆带状覆盖(覆盖带和种植带各30 cm,播种3行,SM₁)、(覆盖带和种植带各40 cm,播种4行,SM₂)、(覆盖带和种植带各50 cm,播种5行,SM₃)5个处理.结果表明: 各处理在不同生育时期、不同土层土壤温度存在显著差异.与CK相比,SM₁、SM₂和SM₃处理全生育期0～25 cm土层土壤温度分别比CK显著降低1.0～1.3 ℃、0.7～0.9 ℃和0.7～1.1 ℃.不同时期比较,覆盖处理存在增温和降温的双重效应,秸秆覆盖在苗期-越冬期具有提高地温的作用,返青期-成熟期具有降温效应,增温效应覆膜>秸秆覆盖,而降温效应秸秆覆盖>覆膜.同时,秸秆覆盖降低了全生育期土壤有效积温和日变化幅度,全生育期有效积温较CK降低3.4～33.5 ℃·d,土壤温差较CK降低0.6～2.0 ℃;秸秆覆盖在越冬期平均温度比CK高0.2～0.3 ℃、负积温比CK高0.4～17.0 ℃·d.秸秆覆盖较CK增产11.9％～19.5％,处理间单位面积穗数的差异是引起产量差异的主要结构因素.因此,秸秆带状覆盖适宜在西北雨养区旱地冬小麦产区推广应用.