Effects of Revegetation on Soil Microbial Biomass,Enzyme Activities,and Nutrient Cycling on the Loess Plateau in China

Revegetation is a traditional practice widely used for soil and water conservation on the Loess Plateau in China. However, there has been a lack of reports on soil microbial–biochemical indices required for a comprehensive evaluation of the success of revegetation systems. In this study, we examined the effects of revegetation on major soil nutrients and microbial–biochemical properties in an artificial alfalfa grassland, an enclosed natural grassland, and an artificial shrubland (Caragana korshinskii), with an abandoned cropland as control. Results showed that at 0–5, 5–20, and 20–40 cm depths, soil organic carbon, alkaline extractable nitrogen and available potassium were higher in natural grassland and artificial shrubland compared with artificial grassland and abandoned cropland. Soil microbial biomass C (Cmic) and phosphorous (Pmic) substantially decreased with depth at all sites, and in abandoned cropland was significantly lower than those of natural grassland, artificial grassland, and artificial shrubland at the depth of 0–5 cm. Soil microbial biomass N (Nmic) was higher in artificial shrubland and abandoned cropland compared with that in natural and artificial grasslands. Both Cmic and Pmic were significantly different between the 23‐year‐old and the 13‐year‐old artificial shrublands at the 0–5 cm depth. The activities of soil invertase, urease, and alkaline phosphatase in natural grassland and artificial shrubland were higher than those in artificial grassland and abandoned cropland. This study demonstrated that the regeneration of both natural grassland and artificial shrubland effectively preserved and enhanced soil microbial biomass and major nutrient cycling, thus is an ecologically beneficial practice for recovery of degraded soils on the Loess Plateau.     

离散广义Logistic模型的稳定性和浑沌现象

文[1]提出了单种生长的连续性文广义Logistic dx/dt=γx({K-x}/(K+px))其中γ>ο为种群的内禀生长率,K>0为环境容纳量,ν>-1表示种群对环境(包括营     

Characterization of ppGalNAc-T18, a member of the vertebrate-specific Y subfamily of UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases

The first step of mucin-type O-glycosylation is catalyzed by members of the UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGalNAc-T; EC 2.4.1.41) family. Each member of this family has unique substrate specificity and expression profiles. In this report, we describe a new subfamily of ppGalNAc-Ts, designated the Y subfamily. The Y subfamily consists of four members, ppGalNAc-T8, -T9, -T17 and -T18, in which the conserved YDX(5)WGGENXE sequence in the Gal/GalNAc-T motif of ppGalNAc-Ts is mutated to LDX(5)YGGENXE. Phylogenetic analysis revealed that the Y subfamily members only exist in vertebrates. All four Y subfamily members lack in vitro GalNAc-transferase activity toward classical substrates possibly because of the UDP-GalNAc-binding pocket mutants. However, ppGalNAc-T18, the newly identified defining member, was localized in the endoplasmic reticulum rather than the Golgi apparatus in lung carcinoma cells. The knockdown of ppGalNAc-T18 altered cell morphology, proliferation potential and changed cell O-glycosylation. ppGalNAc-T18 can also modulate the in vitro GalNAc-transferase activity of ppGalNAc-T2 and -T10, suggesting that it may be a chaperone-like protein. These findings suggest that the new Y subfamily of ppGalNAc-Ts plays an important role in protein glycosylation; characterizing their functions will provide new insight into the role of ppGalNAc-Ts.     

6个线粒体脑肌病伴高乳酸血症和卒中样发作综合征(MELAS)家系先证者线粒体基因全序列比较分析

线粒体脑肌病伴高乳酸血症和卒中样发作综合征(Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes, MELAS)是一种异质性很强的遗传代谢性疾病,而位于tRNA ^Leu(UUR)基因的A3243G突变是该疾病最常见的致病位点。文章对6个汉族MELAS家系的先证者进行了临床病理、分子遗传学特征分析,探讨了线粒体基因多态性对MELAS病人表型可能产生的影响。线粒体基因检测结果显示,4例先证者为A3243G阳性,其异质性比例介于29%~59%之间,临床症状的严重性和异质性程度大致呈正相关;2例MELAS/Leigh叠加综合征先证者为A3243G阴性,复发次数和严重程度重于其他4例先证者,其中1例先证者的血液和肌肉组织中发现ND5基因T13094C突变,该位点已报道与MELAS/Leigh叠加综合征、小脑共济失调相关。另外,线粒体基因全序列测序结果显示：除主要致病突变外,还存在多个与耳聋、癫痫、糖尿病、心肌病、Leigh综合征相关的线粒体基因多态位点,临床症状严重的患者其多态位点也更多。这表明MELAS综合征的复杂表型不仅受致病突变位点的直接影响,也可能受到其他与疾病相关的多态性位点的修饰作用。     

Five New Guaiane Sesquiterpenes from the Endophytic Fungus Xylaria sp. YM 311647 of Azadirachta indica

Five new guaiane sesquiterpenes, 1 – 5 , were isolated from the culture broth of the endophytic fungus Xylaria sp. YM 311647, isolated from Azadirachta indica A. Juss . The structures of these compounds were elucidated on the basis of spectroscopic analyses, and their inhibitory activities against five pathogenic fungi were evaluated. All guaiane sesquiterpenes showed moderate or weak antifungal activities in a broth microdilution assay.     

不同生态环境对蒲公英超氧物歧化酶（SOD）的影响

选择干生,湿生,阳生,阴生四种生境中生长的蒲公英Taraxacum mongolicum Hand.-Mazz分根,叶,花分别测定了SOD活性和比活性,并比较了同工酶谱的变化情况,结果表明不同生境未能改变SOD的同工酶条带数,但对其活性大小有影响,这种影响尤其表现在根上,湿生和阴生根的SOD活性明显高于干生和阳生根的SOD活性,显示出蒲公英的不同器官适应不同的环境效应。     

重组肾上腺髓质素表达载体的构建及在哺乳动物细胞中的表达

为探索通过体内表达肾上腺髓质素（adrenomedullin,AM）治疗高血压和慢性心衰的可能性,本实验构建了重组AM真核表达载体,并在无内源笥AM表达的K562细胞株上进行了体外表达实验。实验中采用RT－PCR技术扩增AM cDNA片段,并将扩增的cDNA片段插入pcDNA3.1真核表达质粒,构建成含AM cDNA的重组质料pcDNA3.1AM。用脂质体介导将该质粒转染培养的人白血病细腻K562株,在转染的细胞中,用RT－PCR检测证实有AM mRNA存在;用班点免疫分析方法检测转染细胞的培养液上清,证实有AM多肽存在,表明本实验中构建的重组pcDNA3.1AM载体能够在哺乳类细胞中表达AM。     

Changes in Florets’ Vertical Direction within Inflorescence Affects Pollinator Behavior,and Fitness in <i>Trifolium repens</i>

Ecological interactions between flowers and pollinators greatly affect the reproductive success. To facilitate these interactions, many flowers are known to display their attractive qualities, such as scent emission, flower rewards and floral vertical direction, in a rhythmic fashion. However, less is known about how plants regulate the relationship between these flower traits to adapt to pollinator visiting behavior and increase reproduction success. Here we investigated the adaptive significance of the flower bending from erect to downward in Trifolium repens. We observed the flowering dynamic characteristics (changes of vertical direction of florets, flowering number, pollen grain numbers, pollen viability and stigma receptivity over time after blossom) and the factors affecting the rate of flower bending in T. repens. Then we altered the vertical direction of florets in inflorescence of different types (upright and downward), and compared the pollinator behaviors and female reproductive success. Our results showed that florets opened sequentially in inflorescence, and then bend downwards slowly after flowering. The bending speed of florets was mainly influenced by pollination, and bending angle increased with the prolongation of flowering time, while the pollen germination rate, stigma receptivity and nectar secretion has a rhythm of “low-high-low” during the whole period with the time going. The visiting frequency of all the four species of pollinators on upward flowers was significantly higher than that of downward flowers, and they especially prefer to visit flowers with a bending angle of 30°–60°, when the flowers was exactly of the highest flower rewards (nectar secretion and number of pollen grains), stigma receptivity and pollen germination rate. The seed set ratio and fruit set ratio of upward flowers were significantly higher than downward flowers, but significantly lower than unmanipulated flowers. Our results indicated that the T. repens could increase female and male fitness by accurate pollination. The most suitable flower angle saves pollinators’ visiting energy and enables them to obtain the highest nectar rewards. This coordination between plants and pollinators maximizes the interests of them, which is a crucial factor in initiating specialized plant-pollinator relationships.     

Differential ConA-enriched urinary proteome in rat experimental glomerular diseases

Glomerular diseases are leading causes of end-stage renal diseases worldwide. They are considered to be consequences of injury primarily to the three types of glomerular cells. Differential diagnosis typically relies on invasive biopsy findings. We expected that injuries of different glomerular cells would cause different changes in urinary proteome. The goal of this study was to identify differential urinary proteins distinguishing between injuries of different glomerular cells before significant histopathologic changes. Adriamycin nephropathy and Thy1.1 glomerulonephritis were employed as models with different primary impaired cells. ConA-enriched urinary glycoproteome on day3 were profiled by gel-free shotgun tandem mass spectrometry, and compared with self-healthy controls to identify differential urinary proteins for each model. By comparing the changes of the differential proteins between these two models, we identified 39 proteins with different directions of changes, which may potentially be useful in differentiation; and 7 proteins with the same direction of changes, which may be potential indicators of early renal damage. These differential proteins were of several origins: plasma proteins, proteins with urine or kidney specificity, proteins without tissue-specificity (mainly inflammatory mediators) etc. Our results may help better understand the effects of injuries of different glomerular cells at the initial stage, and lead to the discovery of novel early diagnostic markers for human focal segmental glomerulosclerosis (FSGS) and mesangioproliferative glomerulonephritis (MsPGN) which have the same primary impaired cells with adriamycin nephropathy and Thy1.1 glomerulonephritis, respectively.     

苦荞锌指蛋白基因FtLSD1的克隆及其对非生物胁迫的应答

根据苦荞(Fagopyrum tataricum)花期转录组数据,分别以苦荞DNA和cDNA为模板,克隆得到1个苦荞C2C2型锌指蛋白基因FtLSD1(GenBank登录号KP252134)的DNA序列和cDNA序列,采用实时荧光定量PCR方法,研究了FtLSD1基因在非生物胁迫下的表达模式。结果显示:苦荞FtLSD1基因DNA全长2 427bp,由6个外显子和5个内含子构成,符合GU-AG剪切原则;cDNA序列包含一个528bp开放阅读框,编码175个氨基酸,具有LSD1家族的典型结构域;UV-B照射和水杨酸处理均能使FtLSD1基因的表达量上升,且UV-B处理在6h达到最大,为0h(CK)的3.84倍;水杨酸处理于10h达到最大,为0h(CK)的3.44倍,而4℃冷胁迫下该基因表达量保持稳定。推测该基因可能参与苦荞抗UV-B和高浓度水杨酸等非生物胁迫的应答反应,为苦荞的抗逆性研究提供新的视角。