Current Location:home > Browse

Authors

Institution

Your conditions: 2018-1(380)

1. chinaXiv:201801.00771 [pdf]

Effects of temperature and water limitation on the germination of Stipagrostis ciliata seeds collected from Sidi Bouzid Governorate in Central Tunisia

Lobna M FAKHFAKH; Naser A ANJUM; Mohamed CHAIEB
Subjects: Biology >> Botany

Most ecological studies in North Africa reveal a process of continuous degradation of rangeland ecosystems as a result of overgrazing. This degradation appears across the decreasing of perennial grass diversity. Indeed, the majority of steppe ecosystems are characterized by a low density of perennial grass species at present. This study evaluated the effects of temperature and water limitation on the seed germination of Stipagrostis ciliata (Desf.) de Winter, a perennial grass species. The seeds were collected from the Bou Hedma Park, Sidi Bouzid Governorate, Central Tunisia. The thermal time and hydrothermal time models were used to describe the seed germination of S. ciliata under different water potentials and temperatures. The germination response of S. ciliata seeds in darkness was evaluated over a range of temperatures (15°C, 20°C, 25°C, 30°C and 35°C) and across a wide range of osmotic potentials (0.0, –0.2, –0.6, –1.2, –1.6 and –2.0 MPa) of the polyethylene glycol (PEG6000) solutions at each temperature level. Among the tested temperatures, 25°C was found to be the optimal temperature to the germination of S. ciliata seeds. The final germination percentage (75.2%) was obtained with distilled water. The progressive decrease of osmotic potential of the PEG6000 solutions inhibited the seed germination. However, the number of days to first germination was increased with a reduction of osmotic potential. A significant positive relationship was identified between final germination percentage of S. ciliata seeds and osmotic potential of the PEG6000 solutions, with R2 ranging from 0.5678 to 0.8761. Furthermore, a high degree of congruency between predicted and observed germination time course curves was observed. In general, S. ciliata exhibits a significant adaptation capacity for water limitation and high temperature in arid ecosystems.

submitted time 2018-01-29 From cooperative journals:《Journal of Arid Land》 Hits1442Downloads584 Comment 0

2. chinaXiv:201801.00772 [pdf]

Potassium forms in calcareous soils as affected by clay minerals and soil development in Kohgiluyeh and Boyer-Ahmad Province, Southwest Iran

Sirous SHAKERI; Seyed A ABTAHI
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science

Potassium (K) is known as one of the essential nutrients for the growth of plant species. The relationship between K and clay minerals can be used to understand the K cycling, and assess the plant uptake and potential of soil K fertility. This study was conducted to analyze the K forms (soluble, exchangeable, non-exchangeable and structural) and the relationship of K forms with clay minerals of calcareous soils in Kohgiluyeh and Boyer-Ahmad Province, Southwest Iran. The climate is hotter and drier in the west and south of the province than in the east and north of the province. A total of 54 pedons were dug in the study area and 32 representative pedons were selected. The studied pedons were mostly located on calcareous deposits. The soils in the study area can be classified into 5 orders including Entisols, Inceptisols, Mollisols, Alfisols and Vertisols. The main soil clay minerals in the west and south of the study area were illite, chlorite and palygorskite, whereas they were smectite, vermiculite and illite in the north and east of the province. Due to large amount of smectite and high content of organic carbon in soil surface, the exchangeable K in surface soils was higher than that in subsurface soils. It seems that organic matter plays a more important role than smectite mineral in retaining exchangeable K in the studied soils. Non-exchangeable K exhibited close relationships with clay content, illite, vermiculite and smectite. Although the amount of illite was the same in almost all pedons, amounts of structural and non-exchangeable K were higher in humid regions than in arid and semi-arid regions. This difference may be related to the poor reservoir of K+ minerals like palygorskite and chlorite together with illite in arid and semi-arid regions. In humid areas, illite was accompanied by vermiculite and smectite as the K+ reservoir. Moreover, the mean cumulative non-exchangeable K released by CaCl2 was higher than that released by oxalic acid, which may be due to the high buffering capacity resulting from high carbonates in soils.

submitted time 2018-01-29 From cooperative journals:《Journal of Arid Land》 Hits11769Downloads1283 Comment 0

3. chinaXiv:201801.00773 [pdf]

Vertical distribution and storage of soil organic and inorganic carbon in a typical inland river basin, Northwest China

YANG Fan; HUANG Laiming; YANG Renmin; YANG Fei; LI Decheng; ZHAO Yuguo; YANG Jinling; LIU Feng; ZHANG Ganlin
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science

Knowledge of soil carbon (C) distribution and its relationship with the environment can improve our understanding of its biogeochemical cycling and help to establish sound regional models of C cycling. However, such knowledge is limited in environments with complex landscape configurations. In this study, we investigated the vertical distribution and storage of soil organic carbon (SOC) and soil inorganic carbon (SIC) in the 10 representative landscapes (alpine meadow, subalpine shrub and meadow, mountain grassland, mountain forest, typical steppe, desert steppe, Hexi Corridor oases cropland, Ruoshui River delta desert, Alxa Gobi desert, and sandy desert) with contrasting bioclimatic regimes in the Heihe River Basin, Northwest China. We also measured the 87Sr/86Sr ratio in soil carbonate to understand the sources of SIC because the ratio can be used as a proxy in calculating the contribution of pedogenic inorganic carbon (PIC) to total SIC. Our results showed that SOC contents generally decreased with increasing soil depth in all landscapes, while SIC contents exhibited more complicated variations along soil profiles in relation to pedogenic processes and parent materials at the various landscapes. There were significant differences of C stocks in the top meter among different landscapes, with SOC storage ranging from 0.82 kg C/m2 in sandy desert to 50.48 kg C/m2 in mountain forest and SIC storage ranging from 0.19 kg C/m2 in alpine meadow to 21.91 kg C/m2 in desert steppe. SIC contributed more than 75% of total C pool when SOC storage was lower than 10 kg C/m2, and the proportion of PIC to SIC was greater than 70% as calculated from Sr isotopic ratio, suggesting the critical role of PIC in the C budget of this region. The considerable variations of SOC and SIC in different landscapes were attributed to different pedogenic environments resulted from contrasting climatic regimes, parent materials and vegetation types. This study provides an evidence for a general trade-off pattern between SOC and SIC, showing the compensatory effects of environmental conditions (especially climate) on SOC and SIC formation in these landscapes. This is largely attributed to the fact that the overall decrease in temperature and increase in precipitation from arid deserts to alpine mountains simultaneously facilitate the accumulation of SOC and depletion of SIC.

submitted time 2018-01-29 From cooperative journals:《Journal of Arid Land》 Hits12425Downloads1316 Comment 1

4. chinaXiv:201801.00700 [pdf]

Morphogenesis of nacreous aragonite tablets: lessons from domed sheet nacre

Zhang, Gangsheng
Subjects: Materials Science >> Materials Chemistry

生物矿化领域的研究者普遍接受珍珠层板片是由非晶质碳酸钙(ACC)纳米颗粒相变而成。然而,这些纳米颗粒在三维空间是如何排列的及如何相变的仍未清楚。本文首次报道了一种新类型不成熟板片,即“枝晶状板片”。这种板片发育在翡翠贻贝珍珠层中。通过与颗粒状板片形貌进行对比,我们发现ACC纳米颗粒通常自组装成垂直的团簇且相变成垂直定向的文石小晶体。这种小晶体与无机成因的文石晶体的平衡形状相同。最重要的是,我们首次发现文石板片与层间有机膜(ILM)呈高的接触角(99-126度)。这表明ILM对ACC纳米颗粒是非润湿的。这种非润湿性可能对珍珠层的形貌成因有重要影响。

submitted time 2018-01-27 Hits18536Downloads1740 Comment 1

5. chinaXiv:201801.00596 [pdf]

丙泊酚对不同发育时期SD大鼠少突胶质细胞鞘磷脂蛋白的影响

朱晓勤; 林春水; 郭培培; 李平; 刘川
Subjects: Medicine, Pharmacy >> Preclinical Medicine

目的 探讨丙泊酚对不同发育时期SD大鼠少突胶质细胞鞘磷脂蛋白(MBP)的影响。方法 取3、 7、 14、 21日龄SD大鼠各 40只,随机分为对照组和实验组,每组20只。对照组(中长链脂肪乳组)和实验组(丙泊酚中长链脂肪乳注射液组)分别腹腔注 射脂肪乳25 mg/kg或丙泊酚25 mg/kg, 隔20 min追加首次剂量的1/2,持续8 h。通过荧光定量RT-qPCR法检测MBP mRNA和 Caspase-3mRNA的表达,Western blot和免疫组化法检测MBP蛋白的表达。结果 与对照组相比,实验组各日龄大鼠MBP mRNA的表达均明显下调(P<0.05), 而3、 7、 14日龄大鼠Caspase-3mRNA表达明显上调(P<0.05)。实验组7、 14日龄大鼠MBP 的表达,与对照组相比显著降低(P<0.05)。两组21日龄Caspase-3mRNA和MBP的表达,差异没有统计学意义(P>0.05)。结 论 丙泊酚可抑制SD大鼠MBP基因与蛋白的表达, 以7、 14日龄最为显著。

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits1704Downloads823 Comment 0

6. chinaXiv:201801.00597 [pdf]

白细胞介素一22促进类风湿关节炎成纤维化膜细胞的增殖

朱俊卿; 王 然; 陈世贤; 赵 迪; 李 娟
Subjects: Medicine, Pharmacy >> Preclinical Medicine

目的 通过白细胞介素-22(IL-22)干预类风湿关节炎(RA)成纤维滑膜细胞(FLS)以期明确IL-22促进其增殖的机制。 方法 无菌条件下获取的RA滑膜组织,应用组织块分离法培养RA-FLS, 含10% FBS的DMEM培养基进行细胞传代培养,并对 第4~5代FLS应用vimentin/CD68进行免疫组化法鉴定;不同浓度的IL-22干预FLS培养24、 48、 72 h后,MTT法检测细胞增殖 程度;联合IL-22和/或AG490干预FLS,于冰面上用含蛋白酶抑制剂的细胞裂解液获取细胞总蛋白,再经超声、离心提取、蛋白 定量后,Western blot法检测STAT3、ERK1/2、 P38蛋白及其磷酸化蛋白的表达,统计分析采用SPSS20.0软件进行, P<0.05为差 异有统计学意义。结果 不同浓度IL-22干预FLS的增殖均较对照组呈梯度增高变化,差异具有统计学意义(P<0.05)。随着IL22干预时间的延长,STAT3总蛋白表达相对灰度值的整体水平差异无统计学意义(P=0.68),但是其磷酸化蛋白表达相对灰度值 整体水平差异具有统计学意义(P<0.001),且在干预的不同时间点STAT3磷酸化蛋白相对表达量较基线0 h时均显著升高, 且 差异具有统计学意义(P<0.001)。IL-22干预后的ERK1/2和P38总蛋白及其磷酸化蛋白表达相对灰度值差异均无统计学意 义(P>0.05)。联合50 ng/mL IL-22和100 μmol/LAG490干预FLS不同时间后,细胞的增殖程度较单用IL-22干预均显著降低 (P<0.01)。结论 IL-22以浓度依赖方式促进RA成纤维化膜细胞STAT3蛋白磷酸化所介导的细胞增殖,而非ERK1/2和P38蛋 白所介导的信号通路。

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits2066Downloads1052 Comment 0

7. chinaXiv:201801.00598 [pdf]

基于介电特性的人体恶性胃组织支持向量机辅助诊断方法

张 洒; 厉 周; 辛学刚
Subjects: Medicine, Pharmacy >> Preclinical Medicine

目的 基于正常和恶性胃组织介电特性值的差异,运用支持向量机(SVM)对介电特性进行自动鉴别。方法 用开端同轴探 头法测量正常和恶性胃组织在42.58~500 MHz频率范围内的介电特性,并对测得的介电特性数据进行Cole-Cole模型拟合。接 收机操作特性(ROC)曲线分析法被用来对各频率点下介电常数、电导率和Cole-Cole拟合参数的鉴别能力进行评估。SVM被 用来对正常和恶性胃组织进行鉴别,鉴别正确率由k折交叉验证进行计算。结果 在测量频率范围内, 5个低端频率点下介电常 数的ROC曲线下面积达到0.8以上。这5个频率下介电常数的组合作为特征值与SVM结合取得了最高鉴别正确率84.38%, MATLAB运行时间为3.40 s。结论 本文提出的基于介电特性的恶性人体胃组织支持向量机辅助诊断方法具有可行性。

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits1513Downloads732 Comment 0

8. chinaXiv:201801.00599 [pdf]

启动子区H3K27me3修饰异常促使系统性红斑狼疮患者CD4+ T细胞CREM过表达

张 庆; 丁 澍; 张慧琳
Subjects: Medicine, Pharmacy >> Preclinical Medicine

目的 探讨SLE中CREMα表达升高的原因。方法 分离5名正常对照和5名SLE患者的CD4+ T细胞,用染色质免疫沉淀 (ChIP)微阵列法对各种基因启动子区组蛋白H3赖氨酸27三甲基化(H3K27me3)的水平进行分析。随后分离30名正常对照和 30名SLE患者的CD4+ T细胞,用ChIP结合实时定量PCR检测CREMα启动子区H3K27me3、 H3K27去甲基化酶JMJD3和 UTX、 H3K27甲基转移酶EZH2的水平,采用实时定量RT-PCR检测CREMα mRNA水平。结果 SLE CD4+ T细胞的CREMα启 动子区H3K27me3水平是正常对照的0.23倍。随后通过ChIP结合实时定量PCR,我们证实了SLE患者CD4+ T细胞CREMα启 动子区H3K27me3水平显著降低(P<0.001),且与CREMα mRNA水平呈显著负相关(P<0.001)。该区的JMJD3水平显著升高 (P<0.001),且与H3K27me3水平呈负相关(P<0.001), 与CREMα mRNA水平呈正相关(P<0.001)。而UTX(P=0.172)及EZH2 (P=0.281)水平则与对照组无明显差异。结论 SLE CD4+ T细胞CREMα启动子区JMJD3增多,导致该区H3K27me3水平降低, 结果促使CREMα过表达,最终引起SLE的发病。

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits1624Downloads765 Comment 0

9. chinaXiv:201801.00600 [pdf]

推桥弓手法对食蟹猴轻度颈动脉粥样硬化模型血流动力学的影响

张 磊; 祁 冀; 景亚军; 覃 波; 李义凯; 刘 刚; 郭晓光; 扶世杰
Subjects: Medicine, Pharmacy >> Preclinical Medicine

目的 探讨推桥弓手法对食蟹猴轻度颈动脉粥样硬化模型血流动力学的影响。方法 选取9只正常食蟹猴,并随机分为3 组(每组3只)推桥弓组、模型对照组、空白对照组。对推桥弓组和模型对照组食蟹猴建立轻度颈动脉粥样硬化模型,然后,对推 桥弓组给予相应手法干预,最后对3组的颈动脉血管情况以及血流动力学进行对比评价。结果(1)在彩超检查中,推桥弓组、 模 型对照组可见斑块形成,同时,在血管横切面面积、斑块横切面面积、斑块狭窄率方面,与空白对照组比较,推桥弓组、模型对照 组差异有统计学意义(P<0.05),而推桥弓组和模型对照组比较,差异无统计学意义(P>0.05)。(2)在各项血流动力学指标中, 与 空白对照组对比,推桥弓组、模型对照组差异有统计学意义(P<0.05),而推桥弓组和模型对照组比较,差异无统计学意义(P> 0.05)。结论 粥样硬化斑块对颈动脉的血流动力学会产生影响,但推桥弓手法在短期内不会影响斑块的稳定性,也不会加重血 流动力学的影响

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits1874Downloads1014 Comment 0

10. chinaXiv:201801.00601 [pdf]

蛋白精氨酸甲基化酶在小鼠外周神经损伤后背根神经节中的转录表达

徐华丽; 徐世元; 磨凯
Subjects: Medicine, Pharmacy >> Preclinical Medicine

目的 探讨蛋白精氨酸甲基化酶(PRMT)在外周神经损伤背根神经节(DRG)转录表达与疼痛行为关系。方法 构建 C57BL6小鼠双侧L4脊神经结扎(SNL)外周神经损伤神经病理性疼痛模型,假手术Sham组作对照,收集SNL或Sham术后第7 天DRG组织, 行RNA-Seq测序全面分析PRMT家族9个基因在转录表达规律和组织分布情况,筛选出差异表达基因;建立小鼠 单侧L4 SNL模型(Sham组作对照),测量各组在SNL术前(0 d)、术后3、 7和14 d不同时点机械缩爪反应频率(PWF)和热缩爪反 应潜伏期(PWL),收集两组上述不同时点患侧和对侧DRG行RT-qPCR验证差异基因表达情况;建立坐骨神经结扎慢性缩窄损 伤(CCI)模型,假手术组Sham作对照,疼痛行为检测方法和时间点同SNL模型,RT-qPCR进一步验证CCI术后上述时点差异基 因表达情况。结果(1)RNA-Seq测序结果表明, 9个PRMT基因均表达与DRG内,其基础表达量最多的是Prmt2和Prmt3,最少 的是Prmt6。与Sham组比较,SNL神经损伤上调DRG Carm1转录表达(增加1.7倍),抑制Prmt5、Prmt8和Prmt9这3个基因转 录,其中Prmt8抑制最明显(下降16.3倍)。(2)RT-qPCR验证表明, 与Sham组较,SNL外周神经损伤增加术后3、 7和14 d PWF, 降低PWL,上调DRG Carm1转录表达,而仅抑制Prmt8转录表达,Prmt1、Prmt5和Prmt9无明显改变。(3)同样的,CCI坐骨神经 损伤亦增加CCI术后3、 7和14 d PWF,降低PWL,上调DRG Carm1,抑制Prmt8在上述时点的表达。结论 外周神经损伤致机 械痛觉高敏和热痛觉过敏的同时,上调DRG Carm1转录表达,抑制Prmt8基因转录

submitted time 2018-01-25 From cooperative journals:《南方医科大学学报》 Hits1786Downloads806 Comment 0

12345678910  Last  Go  [38 Pages/ 380 Totals]