基于茎流-蒸渗仪法的荒漠草原带人工灌丛群落蒸散特征

中国西北地区通过大量种植中间锦鸡儿(Caragana liouana)进行生态治理, 在荒漠草原带上形成人工灌丛景观, 改变了生态系统的结构和功能, 影响到地-气水汽循环过程, 研究该人工灌丛群落的蒸散特征, 对揭示其生态水文效应和指导地方生态治理实践具有重要意义。该文以宁夏盐池荒漠草原带上的人工灌丛群落为例, 利用茎流-蒸渗仪法测定了2018年5-8月的灌木蒸腾和丛下蒸散, 并分析了环境因子对人工灌丛群落蒸散的影响。结果表明: (1)茎流-蒸渗仪法所测的群落蒸散与水量平衡法、涡度相关法得到的群落蒸散有较好的一致性, 茎流-蒸渗仪法能适用于荒漠草原带人工灌丛群落蒸散及其组分结构的测定; (2)观测期内晴天的灌木蒸腾速率和丛下蒸散速率日变化趋势相近, 均为单峰曲线, 群落蒸散主要发生在日间, 但灌丛最大蒸腾速率的出现时间比丛下蒸散最大速率的出现时间晚1 h; (3) 5-8月间灌木累积蒸腾为83.6 mm, 日平均蒸腾量为0.7 mm·d^-1, 季节变化呈抛物线状; 同期丛下累积蒸散为182.5 mm, 日平均蒸散量为1.5 mm·d^-1; 丛下蒸散明显大于灌木蒸腾; (4)观测期间人工灌丛群落累积蒸散266.1 mm, 而同期的降水量为222.6 mm, 陆面水分收支处于亏缺状态; (5)净辐射是影响蒸散最主要、最直接的驱动因素, 且能够影响其他因子进而对人工灌丛群落蒸散产生作用。综上, 人工灌丛引发荒漠草原地带陆面水分收支亏缺的现象, 在生态恢复与重建中须引起注意。     

In Very Young Infants Severity of Acute Bronchiolitis Depends On Carried Viruses

Background

RT amplification reaction has revealed that various single viruses or viral co-infections caused acute bronchiolitis in infants, and RV appeared to have a growing involvement in early respiratory diseases. Because remaining controversial, the objective was to determine prospectively the respective role of RSV, RV, hMPV and co-infections on the severity of acute bronchiolitis in very young infants.

Methods and Principal Findings

209 infants (median age: 2.4 months) were enrolled in a prospective study of infants <1 year old, hospitalized for a first episode of bronchiolitis during the winter epidemic season and with no high risk for severe disease. The severity was assessed by recording SaO₂% at admission, a daily clinical score (scale 0–18), the duration of oxygen supplementation and the length of hospitalization. Viruses were identified in 94.7% by RT amplification reaction: RSV only (45.8%), RV only (7.2%), hMPV only (3.8%), dual RSV/RV (14.3%), and other virus only (2%) or coinfections (9%). RV compared respectively with RSV and dual RSV/RV infection caused a significant less severe disease with a lower clinical score (5[3.2–6] vs. 6[4–8], p = 0.01 and 5.5[5–7], p = 0.04), a shorter time in oxygen supplementation (0[0–1] days vs. 2[0–3] days, p = 0.02 and 2[0–3] days, p = 0.03) and a shorter hospital stay (3[3–4.7] days vs.6 [5–8] days, p = 0.001 and 5[4–6] days, p = 0.04). Conversely, RSV infants had also longer duration of hospitalization in comparison with RSV/RV (p = 0.01) and hMPV (p = 0.04). The multivariate analyses showed that the type of virus carried was independently associated with the duration of hospitalization.

Conclusion

This study underlined the role of RV in early respiratory diseases, as frequently carried by young infants with a first acute bronchiolitis. RSV caused the more severe disease and conversely RV the lesser severity. No additional effect of dual RSV/RV infection was observed on the severity.     

CBP60g and SARD1 play partially redundant critical roles in salicylic acid signaling

Arabidopsis thaliana calmodulin binding protein 60g (CBP60g) contributes to production of salicylic acid (SA) in response to recognition of microbe‐associated molecular patterns (MAMPs) such as flg22, a fragment of bacterial flagellin. Calmodulin binding is required for the function of CBP60g in limiting growth of the bacterial pathogen Pseudomonas syringae pv. maculicola (Pma) ES4326 and activation of SA synthesis. Here, we describe a closely related protein, SARD1. Unlike CBP60g, SARD1 does not bind calmodulin. Growth of Pma ES4326 is enhanced in sard1 mutants. In cbp60g sard1 double mutants, growth of Pma ES4326 is greatly enhanced, and SA levels and expression of PR‐1 and SID2 are dramatically reduced. Expression profiling placed the CBP60g/SARD1 node between the PAD4/EDS1 and SA nodes in the defense signaling network, and indicated that CBP60g and SARD1 affect defense responses in addition to SA production. A DNA motif bound by CBP60g and SARD1, GAAATTT, was significantly over‐represented in promoters of CBP60g/SARD1‐dependent genes, suggesting that expression of these genes is modulated by CBP60g/SARD1 binding. Gene expression patterns showed a stronger effect of cbp60g mutations soon after activation of a defense response, and a stronger effect of sard1 mutations at later times. The results are consistent with a model in which CBP60g and SARD1 comprise a partially redundant protein pair that is required for activation of SA production as well as other defense responses, with CBP60g playing a more important role early during the defense response, and SARD1 to playing a more important role later.     

The Disintegrin and Metalloprotease ADAM12 Is Associated with TGF-β-Induced Epithelial to Mesenchymal Transition

The increased expression of the Disintegrin and Metalloprotease ADAM12 has been associated with human cancers, however its role remain unclear. We have previously reported that ADAM12 expression is induced by the transforming growth factor, TGF-β and promotes TGF-β-dependent signaling through interaction with the type II receptor of TGF-β. Here we explore the implication of ADAM12 in TGF-β-mediated epithelial to mesenchymal transition (EMT), a key process in cancer progression. We show that ADAM12 expression is correlated with EMT markers in human breast cancer cell lines and biopsies. Using a non-malignant breast epithelial cell line (MCF10A), we demonstrate that TGF-β-induced EMT increases expression of the membrane-anchored ADAM12L long form. Importantly, ADAM12L overexpression in MCF10A is sufficient to induce loss of cell-cell contact, reorganization of actin cytoskeleton, up-regulation of EMT markers and chemoresistance. These effects are independent of the proteolytic activity but require the cytoplasmic tail and are specific of ADAM12L since overexpression of ADAM12S failed to induce similar changes. We further demonstrate that ADAM12L-dependent EMT is associated with increased phosphorylation of Smad3, Akt and ERK proteins. Conversely, inhibition of TGF-β receptors or ERK activities reverses ADAM12L-induced mesenchymal phenotype. Together our data demonstrate that ADAM12L is associated with EMT and contributes to TGF-β-dependent EMT by favoring both Smad-dependent and Smad-independent pathways.     

Evidence for Nerve Growth Factor-Potentiating Activities of the Nonpeptidic Compound SR 57746A in PC12 Cells

Abstract: SR 57746A {1-[2-(naphth-2-yl)ethyl]-4-(3-trifluoromethylphenyl)-1,2,5,6-tetrahydropyridine hydrochloride} exhibits neurotrophic activities in vivo and in vitro. We used the rat pheochromocytoma PC12 cell line to investigate in vitro cellular changes induced by SR 57746A. A significant increase in the percentage of cells bearing neurite-like processes was obtained in cells treated by SR 57746A and nerve growth factor (NGF) compared with NGF treatment alone. SR 57746A added alone, however, had no effect on morphogenesis or on survival of cells in serum-free medium. In contrast, SR 57746A induced a "priming" effect on PC12 cells for neurite outgrowth within 6 h of addition of the protein tyrosine kinase inhibitor genistein. An increase in α-actinin content resulted from treatment with SR 57746A. Expression of NGF-mediated acetylcholinesterase and choline acetyltransferase was enhanced within 5 days by SR 57746A. The molecule also induced rapid F-actin redistribution. Within 2 min of incubation, outgrowth of F-actin-containing filopodia was clearly visible at the cell periphery, as previously shown with NGF. It is interesting that this effect of SR 57746A could be mimicked by protein tyrosine kinase inhibitors and abolished by preincubation with sodium orthovanadate, a protein tyrosine phosphatase inhibitor.     

Two cultivated legume plants reveal the enrichment process of the microbiome in the rhizocompartments

The microbiomes of rhizocompartments (nodule endophytes, root endophytes, rhizosphere and root zone) in soya bean and alfalfa were analysed using high‐throughput sequencing to investigate the interactions among legume species, microorganisms and soil types. A clear hierarchical filtration of microbiota by plants was observed in the four rhizocompartments – the nodule endosphere, root endosphere, rhizosphere and root zone – as demonstrated by significant variations in the composition of the microbial community in the different compartments. The rhizosphere and root zone microbial communities were largely influenced by soil type, and the nodule and root endophytes were primarily determined by plant species. Diverse microbes inhabited the root nodule endosphere, and the corresponding dominant symbiotic rhizobia belonged to Ensifer for alfalfa and Ensifer–Bradyrhizobium for soya bean. The nonsymbiotic nodule endophytes were mainly Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes. The variation in root microbial communities was also affected by the plant growth stage. In summary, this study demonstrated that the enrichment process of nodule endophytes follows a hierarchical filtration and that the bacterial communities in nodule endophytes vary according to the plant species.