聚苯乙烯纳米塑料-植物蛋白冠的形成与特征

为探究聚苯乙烯纳米塑料-植物蛋白冠的形成过程以及蛋白冠的形成对植物可能造成的影响,本研究选用3种平均粒径为200nm不同表面修饰的聚苯乙烯纳米塑料微球和新几内亚凤仙(Impatiens hawkeri)为对象,将3种聚苯乙烯纳米塑料分别与新几内亚凤仙的叶蛋白提取物进行反应,反应时间分别为2、4、8、16、24、36 h。利用扫描电镜(scanning electron microscopy, SEM)观察其形貌变化,原子力显微镜(atomic force microscopy, AFM)进行表面粗糙度测定,使用纳米粒度和zeta电位分析仪测定水合粒径及zeta电位,液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry, LC-MS/MS)鉴定蛋白冠的蛋白成分。从生物学过程、细胞组分以及分子功能3个方面对蛋白进行分类,研究不同表面修饰的纳米塑料对蛋白的吸附选择,探究聚苯乙烯纳米塑料-植物蛋白冠的形成与特征,预测蛋白冠对植物造成的可能影响。结果表明：随着反应时间增加,纳米塑料的形貌变化越发明显,表现为尺寸和粗糙度的增加和稳定性的增...     

Climate change impacts on asphalt road pavement construction and maintenance: An economic life cycle assessment of adaptation measures in the State of Virginia,United States

Pavement design and management practices must be adapted in response to future climate change. While many studies have attempted to identify different methods to adapt pavements to future climate conditions, the potential economic impacts of the adaptations still remain largely unquantified. This study presents the results of a comprehensive life‐cycle cost analysis (LCCA) aimed at quantifying the potential economic impacts of a climate adaptation method, in which an upgraded asphalt binder (Performance Grade PG 76‐22) is used in the construction and maintenance of flexible pavement sections in lieu of the original binder (PG 70‐22) for improved resistance against high temperatures. For each of three major Virginia Department of Transportation (VDOT) districts with different climates, three case studies consisting of typical interstate, primary, and secondary pavement sections were considered. The LCCA accounted for the costs incurred during the mixture's production, maintenance, and use phases of the pavement life cycle by explicitly considering future climate projections, pavement life‐cycle performance, maintenance effects, and work zone user delays. The study concludes that pavements using the upgraded binder not only perform better over time but are also economically advantageous compared to those with the original binder under the conditions of the anticipated future climate conditions (2020–2039).     

白蚁-共生微生物系统降解木质纤维素研究进展

开发利用木质纤维素材料能显著增加地球上可再生资源的储备量。白蚁分布广泛,常见于热带和亚热带地区,它们借助细菌、古细菌、真菌等肠道微生物和原生动物协同降解食物中的木质纤维素,在生态系统的碳、氮循环中发挥着十分重要的作用。本文概括了近年来白蚁肠道微生物研究的进展,特别是近年来已被证明的肠道微生物在木质纤维素降解方面的作用,以期为后续研究木质纤维素的降解提供参考信息。     

Physiological response of riparian plants to watering in hyper-arid areas of Tarim River, China

The physiological responses and adaptive strategies of Populus euphratica Oliv. (arbor species), Tamarix ramosissima Ldb. (bush species), and Apocynum venetum L. (herb species) to variations in water and salinity stress were studied in the hyper-arid environment of the Tarim River in China. The groundwater table, the saline content of the groundwater, as well as the content of free proline, soluble sugars, plant endogenous hormones (abscisic acid (ABA), and cytokinins (CTK)) of the leaves of the three species were monitored and analyzed at the lower reaches of the Tarim River in the study area where five transects were fixed at 100 m intervals along a vertical sampling line before and after water release. Saline stress dramatically increased soluble sugar concentration of the three species. Differences in sugar accumulation were determined among the species at different transects. The free proline concentration of the leaves of T. ramosissima and P. euphratica showed a proportional decrease with various degrees of elevation of the groundwater table after water release. There was a least correlation between the soluble sugars and proline stimulation in T. ramosissima. It was strongly suggested that T. ramosissima developed a different strategy to accumulate organic solutes to adapt to the stress environment. The soluble sugars and proline accumulation responded to the changes of groundwater table independently: the former occurred under salt stress, whereas the latter was more significant under drought stress. The concentration and the increase in concentration of ABA and CTK involved in stress resistance of the three species were also determined. This increase in the hormone concentration in P. euphratica was different from that of the other two species. Expressed as a function of increase of ABA concentration in leaves, A. venetum and T. ramosissima showed a different solute accumulation in response to groundwater table. There was a significant correlation between ABA accumulation and Δ [proline] in A. venetum as well as between ABA accumulation and Δ [sugar] in T. ramosissima. Translated from Acta Ecologica Sinica, 2005, 25(8): 1966–1973 [译自: 生态学报]     

Drosophila klaroid encodes a SUN domain protein required for Klarsicht localization to the nuclear envelope and nuclear migration in the eye

KASH (Klarsicht/Anc-1/Syne homology) domain proteins are cytoskeleton-associated proteins localized uniquely to the outer nuclear membrane. Klarsicht is a KASH protein required for nuclear migration in differentiating cells of the Drosophila eye. The C-terminal KASH domain of Klarsicht resides in the perinuclear space, and the cytoplasmic moiety connects to the microtubule organizing center. In C. elegans and vertebrate cells, SUN (Sad1/UNC-84) domain proteins reside in the inner nuclear membrane and tether KASH proteins to the outer nuclear membrane. Is there a Drosophila SUN protein that performs a similar function, and if so, is it like Klarsicht, obviously essential for nuclear positioning only in the eye? Here, we identify Drosophila Klaroid, a SUN protein that tethers Klarsicht. klaroid loss-of-function mutants are indistinguishable phenotypically from klarsicht mutants. Remarkably, neither gene is essential for Drosophila viability or fertility, and even in klaroid klorsicht double mutants, the only obvious external morphological defect is rough eyes. In addition, we find that klaroid and klarsicht are required for nuclear migration in differentiating neurons and in non-neural cells. Finally, while perinuclear Klaroid is ubiquitous in the eye, Klarsicht expression is limited to differentiating cells and may be part of the trigger for apical nuclear migration.     

Statistical significance for hierarchical clustering in genetic association and microarray expression studies

Background  

With the increasing amount of data generated in molecular genetics laboratories, it is often difficult to make sense of results because of the vast number of different outcomes or variables studied. Examples include expression levels for large numbers of genes and haplotypes at large numbers of loci. It is then natural to group observations into smaller numbers of classes that allow for an easier overview and interpretation of the data. This grouping is often carried out in multiple steps with the aid of hierarchical cluster analysis, each step leading to a smaller number of classes by combining similar observations or classes. At each step, either implicitly or explicitly, researchers tend to interpret results and eventually focus on that set of classes providing the "best" (most significant) result. While this approach makes sense, the overall statistical significance of the experiment must include the clustering process, which modifies the grouping structure of the data and often removes variation.     

Anti-Inflammatory Effects of Ang-(1-7) in Ameliorating HFD-Induced Renal Injury through LDLr-SREBP2-SCAP Pathway

The angiotensin converting enzyme 2-angiotensin-(1–7)-Mas axis (ACE2-Ang-(1–7)-Mas axis) is reported to participate in lipid metabolism in kidney, but its precise effects and underlying mechanisms remain unknown. We hypothesized that Ang-(1–7) reduces lipid accumulation and improves renal injury through the low density lipoprotein receptor–sterol regulatory element binding proteins 2–SREBP cleavage activating protein (LDLr-SREBP2-SCAP) system by suppressing inflammation in high fat diet (HFD)-fed mice. In this study, male C57BL/6 mice were randomized into four groups: STD (standard diet)+saline, HFD+saline, HFD+Ang-(1–7) and STD+Ang-(1–7). After 10 weeks of feeding, mice were administered Ang-(1–7) or saline for two weeks. We found that high inflammation status induced by HFD disrupted the LDLr-SREBP2-SCAP feedback system. Treatment of mice fed a high-fat diet with Ang-(1–7) induced significant improvement in inflammatory status, following the downregulation of LDLr, SREBP2 and SCAP, and then, decreased lipid deposition in kidney and improved renal injury. In conclusion, the anti-inflammatory effect of Ang-(1–7) alleviates renal injury triggered by lipid metabolic disorders through a LDLr- SREBP2-SCAP pathway.     

Effect and mechanism of the Ang-(1-7) on human mesangial cells injury induced by low density lipoprotein

Hyperlipidemia is an independent risk factor for renal disease, and lipid deposition is associated with glomerulosclerosis. The angiotensin converting enzyme 2-angiotensin-(1-7)-Mas axis (ACE2-Ang-(1-7)-Mas axis) has been reported to participate in lipid metabolic regulation but its mechanism remains unclear. We hypothesized Ang-(1-7) would reduce lipid uptake in human mesangial cells (HMCs) by regulating the low density lipoprotein receptor–sterol regulatory element binding proteins 2–SREBP cleavage activating protein (LDLr–SREBP2–SCAP) negative feedback system, and improve glomerulosclerosis by regulating the transforming growth factor-β1 (TGF-β1). In this study we found that ACE2 was undetected in HMCs. The administration of LDL caused normal LDLr–SREBPs–SCAP negative feedback effect. Exogenous Ang-(1-7) enhanced this negative feedback effect via down-regulating LDLr, SREBP2, and SCAP expression, and effectively inhibited LDL-induced lipid deposition and cholesterol increases. This enhanced inhibitory effect was reversed by the Mas receptor antagonist A-779. Meanwhile, Ang-(1-7) significantly decreased the high LDL-induced production of TGF-β1, an effect blocked by A-779. Interestingly, HMCs treated with Ang-(1-7) alone activated the TGF-β1 expression. Our results suggested that Ang-(1-7) inhibits LDL accumulation and decreases cholesterol levels via modulating the LDLr–SREBPs–SCAP negative feedback system through the Mas receptor. Moreover, Ang-(1-7) exhibits a dual regulatory effect on TGF-β1 in HMCs.     

A Sir2-like protein participates in mycobacterial NHEJ

In eukaryotic cells, repair of DNA double-strand breaks (DSBs) by the nonhomologous end-joining (NHEJ) pathway is critical for genome stability. In contrast to the complex eukaryotic repair system, bacterial NHEJ apparatus consists of only two proteins, Ku and a multifunctional DNA ligase (LigD), whose functional mechanism has not been fully clarified. We show here for the first time that Sir2 is involved in the mycobacterial NHEJ repair pathway. Here, using tandem affinity purification (TAP) screening, we have identified an NAD-dependent deacetylase in mycobacteria which is a homologue of the eukaryotic Sir2 protein and interacts directly with Ku. Results from an in vitro glutathione S-transferase (GST) pull-down assay suggest that Sir2 interacts directly with LigD. Plasmid-based end-joining assays revealed that the efficiency of DSB repair in a sir2 deletion mutant was reduced 2-fold. Moreover, the Δsir2 strain was about 10-fold more sensitive to ionizing radiation (IR) in the stationary phase than the wild-type. Our results suggest that Sir2 may function closely together with Ku and LigD in the nonhomologous end-joining pathway in mycobacteria.