叉蕨科30种植物叶表皮形态特征研究

利用光镜对叉蕨科7属30种植物叶表皮形态特征进行详细观察研究。结果显示：（1）叉蕨科30种植物的叶上表皮和下表皮细胞形状均为不规则型,垂周壁式样为深波状或浅波状,具单晶或针晶;上表皮细胞的长宽比为1.62~4.0,下表皮细胞的长宽比为1.63~3.06。（2）在30种植物中共观察到7种气孔器类型,分别为：极细胞型、腋下细胞型、聚合极细胞型、聚腋下细胞型、不等细胞型、无规则四细胞型和不规则型,每种植物分别具有4~7种气孔器类型,均为下生型气孔;气孔长宽比为1.22~1.91,气孔密度为8~76个/mm²,气孔指数为3.9%~25.7%。（3）基于气孔器类型组成进行聚类分析,可将30种植物分成3个类群。（4）对叶表皮形态特征分析认为,轴脉蕨属应介于叉蕨属和肋毛蕨属之间,且与叉蕨属关系更近;叉蕨属的范畴还有待进一步研究;支持将肋毛蕨属从叉蕨科中分离出来置于鳞毛蕨科,但不支持黄腺羽蕨属归入鳞毛蕨科。     

青藏高原湿地植物轻金属元素含量特征及其与环境因素的关系研究

以青藏高原湿地植物为研究对象,通过对青藏高原35个采样点的野外调查采样,对青藏高原湿地植物8种轻金属元素(Al、Mg、Ca、Sr、Ba、K、Na、Li)含量的特征及其与环境因素的关系进行分析。结果显示,不同湿地植物对不同轻金属元素的富集能力存在差异。轻金属元素在湿地植物体内的平均含量依次排序为:Li相似文献   

Arabidopsis CSN5B Interacts with VTC1 and Modulates Ascorbic Acid Synthesis

Light regulates ascorbic acid (AsA) synthesis, which increases in the light, presumably reflecting a need for antioxidants to detoxify reactive molecules produced during photosynthesis. Here, we examine this regulation in Arabidopsis thaliana and find that alterations in the protein levels of the AsA biosynthetic enzyme GDP-Man pyrophosphorylase (VTC1) are associated with changes in AsA contents in light and darkness. To find regulatory factors involved in AsA synthesis, we identified VTC1-interacting proteins by yeast two-hybrid screening of a cDNA library from etiolated seedlings. This screen identified the photomorphogenic factor COP9 signalosome subunit 5B (CSN5B), which interacted with the N terminus of VTC1 in yeast and plants. Gel filtration profiling showed that VTC1-CSN5B also associated with the COP9 signalosome complex, and this interaction promotes ubiquitination-dependent VTC1 degradation through the 26S proteasome pathway. Consistent with this, csn5b mutants showed very high AsA levels in both light and darkness. Also, a double mutant of csn5b with the partial loss-of-function mutant vtc1-1 contained AsA levels between those of vtc1-1 and csn5b, showing that CSN5B modulates AsA synthesis by affecting VTC1. In addition, the csn5b mutant showed higher tolerance to salt, indicating that CSN5B regulation of AsA synthesis affects the response to salt stress. Together, our data reveal a regulatory role of CSN5B in light-dark regulation of AsA synthesis.     

First Record of Cenozoic Bird Footprints from East Asia (Tibet,China)

Cenozoic bird tracks are known largely from North America, Europe, and the Middle East. There have been no reports of Cenozoic bird tracks from East Asia. This paper describes a series of two trackways produced by a galliform-like or gruiform-like bird from the Oligocene to Early Miocene of Tibet. The tracks are represented by tracings collected from a coal mine in Shigatse, Tibet, during the late 1970s. The tracks are comparable to Ornithoformipes and Pavoformipes and likely represent a medium-sized to large cursorial or flightless bird. In relation to modern bird tracks, the tracks bear a striking resemblance to those produced by the North American Wild Turkey (Meleagris gallopavo) except that M. gallopavo tracks often possess a small, elevated hallux impression. Due to the fact that these are tracings, however, a hallux may have been present and simply have been overlooked. The Shigatse trackways were, unfortunately, lost when the mine was closed and then backfilled during the 1980s, and there is little to no likelihood of recovery. Casts can be catalogued as holotype specimens but tracings cannot; however, all the original tracings have been donated to a public institution by their discoverer, Yimin Wu.     

Ethanol induced the formation of β‐sheet and amyloid‐like fibrils by surfactant‐like peptide A6K

Self‐assembly of natural or designed peptides into fibrillar structures based on β‐sheet conformation is a ubiquitous and important phenomenon. Recently, organic solvents have been reported to play inductive roles in the process of conformational change and fibrillization of some proteins and peptides. In this study, we report the change of secondary structure and self‐assembling behavior of the surfactant‐like peptide A6K at different ethanol concentrations in water. Circular dichroism indicated that ethanol could induce a gradual conformational change of A6K from unordered secondary structure to β‐sheet depending upon the ethanol concentration. Dynamic light scattering and atomic force microscopy revealed that with an increase of ethanol concentration the nanostructure formed by A6K was transformed from nanosphere/string‐of‐beads to long and smooth fibrils. Furthermore, Congo red staining/binding and thioflavin‐T binding experiments showed that with increased ethanol concentration, the fibrils formed by A6K exhibited stronger amyloid fibril features. These results reveal the ability of ethanol to promote β‐sheet conformation and fibrillization of the surfactant‐like peptide, a fact that may be useful for both designing self‐assembling peptide nanomaterials and clarifying the molecular mechanism behind the formation of amyloid fibrils. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Determination of carbamazepine in human urine and serum samples by high‐performance liquid chromatography with post‐column Ru(bipy)‐Ce(SO4)2 chemiluminescence detection

A novel, sensitive and rapid CL method coupled with high‐performance liquid chromatography separation for the determination of carbamazepine is described. The method was based on the fact that carbamazepine could significantly enhance the chemiluminescence of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium(II) in the presence of acid. The chromatographic separation was performed on a Kromasil® (Sigma‐Aldrich) TM RP‐C18 column (id: 150 mm × 4.6 mm, particle size: 5 µm, pore size: 100 Å) with a mobile phase consisting of methanol–water‐glacial acetic acid (70:29:1, v/v/v) at a flowrate of 1.0 mL/min, the total analysis time was within 650 s. Under optimal conditions, CL intensity was linear for carbamazepine in the range 2.0 × 10^?8 ~ 4.0 × 10^?5 g/mL, with a detection limit of 6.0 × 10^?9 g/mL (S/N = 3) and the relative standard detection was 2.5% for 2.0 × 10^?6 g/mL (n = 11). This method was successfully applied to the analysis of carbamazepine in human urine and serum samples. The possible mechanism of the CL reaction is also discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.