土壤藻生物量及其在荒漠结皮的影响因子

土壤藻生物量方法方面的不统一和操作性误差已长时间影响着土壤藻的研究进展。以沙坡头不同龄荒漠土壤为样点 ,通过直接计数、培养计数、体积换算等方法的比较分析 ,提出了土壤藻生物量相对规范的测定和计量方法——体积法 ;测定当地无灌溉人工区结皮中生物量为 5 .99～ 8.5 8mm3/g dry soil,灌溉区1 .2 8mm3/g dry soil,最高值出现在 8月份 ,最低值出现在 2月份 ;与当地小气候、土壤理化性质等 33项环境因子逐步回归显示 ,它们与当地降水量、土壤中总钾、水解氮、Fe3+ 、粗

宁夏回族自治区沙坡头地区半荒漠土壤中藻类的垂直分布

对沙坡头地区半荒漠土壤中藻类植物的垂直分布进行了为期一年多的采样、分析 ,结果发现结皮层有藻类植物 2 4种 ,蓝藻及其丝状种类的比例最大 ;结皮下 0～ 5 0 mm和 5 0～ 1 0 0 mm层次分别有 1 5种、1 0种 ,且都以硅藻及单细胞种类最丰富 ;深层次出现的种类在浅层次都出现 ;1 0 0 mm以下层次没有任何藻种发现。生物量从表及里随深度的增加而锐减 ,99%的分布在结皮层 ;就结皮层中 78%的在 0～ 0 .1 mm层次 ,96%在 0～ 1 .0 mm深度。种类数变化在结皮层和结

乳头瘤病毒及协同因子与宫颈癌的关系

本研究旨在探讨宫颈癌前病变和宫颈癌的发生发展与人乳头瘤病毒及协同因子 (HSV ,CMV)的关系。对81例不同宫颈病变组织进行HPV16 / 18和HPV6 / 11原位杂交 ,同时对 10 3例不同宫颈病变组织用DNA扩增法检测HPV、HSV和CMV。结果表明病毒DNA原位杂交信号的分布与HE染色中挖空细胞的分布一致。HPV16 / 18与不同宫颈病变组织原位杂交阳性率平均为 5 1% ,HPV6 / 11的则为 6 4%。经PCR检测 ,HPV16 / 18、HPV6 / 11、HSV、CMV在不同宫

藏北 3种裸鲤同工酶的电泳分析及物种分化的探讨(英文)

对藏北高原 3种裸鲤的乳酸脱氢酶(LDH)、苹果酸脱氢酶 (MDH )和脂酶 (EST)进行电泳分析的结果表明 ,3种裸鲤酶谱均表现出种间的差别 ,而且在同一种群个体之间也存在着明显的分化 ,但无性别差异。 3种裸鲤被检测的 3种同工酶均有沉默基因表达的现象 ,重复基因LDH -A2 、LDH -B2 、s -MDH -A2 和m -MDH -B2 也在部分个体中表达。遗传距离分析表明 ,色林错裸鲤(G .selincuoensis)与错鄂裸鲤 (G .cuoensis)之间较之于与纳木错裸鲤 (G .n

Flipped physics

This paper defines flipped learning and then examines its practical implementation in AS and A2 level physics classes, that is, classes for 16-18 year olds. The effect of this teaching style on student learning behaviour and its impact on test results are evaluated. The paper recounts the difficulties of implementing it and evaluates student preferences. It concludes with comments about this teaching style's appropriateness for various groups of students and identifies those for whom it is not suitable. A list of useful websites is included. © 2013 IOP Publishing Ltd.

The effect of different dietary iron levels on growth and hepatic iron concentration in juvenile gibel carp (Carassius auratus gibelio)

P>An 83-day growth trial was conducted using a flow-through system to examine the effects of different dietary iron levels on growth and hepatic iron concentration in juvenile gibel carp (Carassius auratus gibelio). Six purified diets supplemented with different levels of iron (0, 10, 30, 60, 100 and 200 mg kg(-1)) (as ferrous sulfate) were fed to triplicate groups of fish (initial weight 2.12 +/- 0.00 g per fish). The results showed that the addition of iron to the basal diet did not significantly affect the specific growth rate (SGR), feed efficiency (FE), survival, red blood cell amount (RBC), hemoglobin content (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) or mean corpuscular hemoglobin concentration (MCHC). Hepatic iron concentration and hematocrit (Hct) were significantly influenced by dietary iron level (P < 0.05). On the basis of the iron concentration for the maintenance of optimum hepatic iron concentration and Hct, it was concluded that the dietary iron concentration of juvenile gibel carp should be not less than 202 mg Fe kg(-1) diet.

Cloning, characterization, and gene expression analysis of a novel cadmium metallothionein gene in Tetrahymena pigmentosa

A novel cadmium-inducible metallothionein (MT) gene (Tpig-MT1) was cloned and sequenced from the ciliate Tetrahymena pigmentosa. The number of deduced amino acids is 118. The polypeptide possesses CCC and CC clusters characteristic of typical Tetrahymena Cd-inducible MTs. The structure of Tpig-MT1 is different from the reported Cd-MT in T. pyriformis, T. thermophila and T. pigmentosa. Tpig-MT1 contains two intragenic tandem repeats with 72.9% identity described as Tpig-MT1 (repeat A1) and Tpig-MT1 (repeat A2). The transcriptional response of Tpig-MT1 gene to different heavy metals (Cd, Cu, Zn, Hg, Pb) and oxidative stress (H2O2) was measured using real-time quantitative PCR. The results showed that the gene was quickly induced (1 h) by the five heavy metals and the order of expression level was Hg>Pb>Cd>Cu>Zn. The induction effect of H2O2 was 5-fold after about 15 min, but soon decreased to a non-significant level (30 min). The genetic diversity of Tetrahymena MT genes is discussed in relation to the unique structure of the Tpig-MT1 gene and other reported Cd-MT isoforms. (C) 2008 Elsevier B.V. All rights reserved.

C1q-like inhibits p53-mediated apoptosis and controls normal hernatopoiesis during zebrafish embryogenesis

Except for the complement C1q, the immunological functions of other C1q family members have remained unclear. Here we describe zebrafish C1q-like, whose transcription and translation display a uniform distribution in early embryos, and are restricted to mid-hind brain and eye in later embryos. In vitro studies showed that C1q-like could inhibit the apoptosis induced by ActD and CHX in EPC cells, through repressing caspase 3/9 activities. Moreover, its physiological roles were studied by morpholino-mediated knockdown in zebrafish embryogenesis. In comparison with control embryos, the C1q-like knockdown embryos display obvious defects in the head and cramofacial development mediated through p53-induced apoptosis, which was confirmed by the in vitro transcribed C1q-like mRNA or p53 MO co-injection. TUNEL assays revealed extensive cell death, and caspase 3/9 activity measurement also revealed about two folds increase in C1q-like morphant embryos, which was inhibited by p53 MO co-injection. Real-time quantitative PCR showed the up-regulation expression of several apoptosis regulators such as p53, mdm2, p21, Box and caspase 3, and down-regulation expression of hbae1 in the C1q-like morphant embryos. Knockdown of C1q-like in zebrafish embryos decreased hemoglobin production and impaired the organization of mesencephalic vein and other brain blood vessels. Interestingly, exposure of zebrafish embryos to UV resulted in an increase in mRNA expression of C1q-like, whereas over-expression of C1q-like was not enough resist to the damage. Furthermore, C1q-like transcription was up-regulated in response to pathogen Aeromonas hydrophila, and embryo survival significantly decreased in the C1q-like morphants after exposure to the bacteria. The data suggested that C1q-like might play an antiapoptotic and protective role in inhibiting p53-dependent and caspase 3/9-mediated apoptosis during embryogenesis, especially in the brain development, and C1q-like should be a novel regulator of cell survival during zebrafish embryogenesis. (c) 2008 Elsevier Inc. All rights reserved.

Hematological and plasma biochemical responses of crucian carp (Carassius auratus) to intraperitoneal injection of extracted microcystins with the possible mechanisms of anemia

Alterations in hematological indices such as decreases in blood cell counts (RBC), hematocrit (Ht) and hemoglobin (Hb) concentrations are key symptoms of anemia. However, few experiments were conducted to examine changes in hematological indices of fish exposed to microcystins that are believed to be fatal to circulatory systems of vertebrates. An acute toxicological experiment was designed to study hematological changes of crucian carp injected intraperitoneally (i.p.) with extracted microcystins at two doses, 50 and 200 mu g MC-LReqkg(-1) body weight. After being i.p. injected with microcystins, the fish exhibited behavioral abnormity. There were significant decreases in RBC in the high-dose group, and in Ht and Hb concentrations in both dose groups, while erythrocte sedimentation rate (ESR) significantly increased, indicating the appearance of normocytic anemia. There were no prominent changes in the three red cell indices, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH,), and mean corpuscular hemoglobin concentration (MCHC). Increases in blood urea nitrogen (BUN) and creatinine (CR) in both dose groups suggest the occurrence of kidney impairment. Alteration in blood indices was reversible at the low dose group. Conclusively, anemia induced by kidney impairment was a key factor to cause abnormity of swimming behaviors and high mortality of crucian carp. (c) 2007 Elsevier Ltd. All rights reserved.

Differential gene expression in fully-grown oocytes between gynogenetic and gonochoristic crucian carps

Silver crucian carp (Carassius auratus gibelio) is a unique triploid bisexual species that can reproduce by gynogenesis. As all other gynogenetic animals, it keeps its chromosome integrity by inhibiting the first meiosis division (no extrusion of the first pole body). To understand the molecular events governing this reproduction mode, suppression subtractive hybridization was used to identify the genes differentially expressed in fully-grown oocytes of the gynogenetic and gonochoristic crucian carp (gyno-carp and gono-carp). From two specific subtractive cDNA libraries, the clones screened out by dot blots and virtual Northern blots were chosen to clone, full-length cDNA by RACE. Four differentially expressed genes were obtained. Two are novel genes and are expressed specifically in the oocytes. The gyno-carp stores much more mRNA of cyclin A2, a new member of the fish A-type cyclin gene, in its fully-grown oocyte than in the gono-carp. The last gene is histone H2A. The histone H2As of these two closely related crucian carps are quite different in the C-terminus. Preliminary characterization of the four genes has been analyzed by nucleotide and deduced amino acid sequence and Northern analysis. (C) 2001 Elsevier Science B.V. All rights reserved.

支持移动和普适应用的上下文感知框架

蕴涵着高度动态变化特性的移动和普适计算环境给分布式系统的设计提出了新的挑战,上下文感知框架汇聚了感知和处理各种易变因素的基础设施.依托框架开发移动和普适应用,能加快开发速度,提高应用程序的健壮性.本文分析了各种上下文信息及其作用,给出了上下文感知框架XAF的设计,探讨了框架中的关键技术,包括上下文转换和服务自适应选择.

基于CLIGEN和GCM模型预测未来40年黄土丘陵沟壑区的气候变化——以安塞为例

为预测3种温室气体排放情景(A2、B2和GGa1)下未来40年黄土丘陵沟壑区的气候变化,利用安塞试验站1986—2003年的气候观测资料以及1986—2049年GCM(HadCM3)栅格数据,通过空间转换和时间转换,利用CLIGEN和GCM模型,预测未来40年以安塞为代表的黄土高原丘陵沟壑区的气候变化。结果表明:与当前条件相比,到2049年,A2、B2和GGa1 3种情景下预测的降雨量分别增加37%、22%和12%;3种情景下预测的最大月均降雨量出现在夏季;到2049年,A2、B2和GGa1 3种情景下预测的月均最低气温和月均最高气温皆增加,但差异不明显,年均最低气温和年均最高气温分别增加1.41~1.56℃和0.92~1.57℃。

新型靶向性磁共振成像造影剂的合成及性质研究

磁共振成像(magnetic resonance imaging, MRI)以其分辨率高、对人体无电离辐射损伤、多参数成像等优点而得到迅速发展和广泛应用。目前，MRI已从单一形态学向分子影像学的深度发展，对医学临床和医学研究产生了巨大影响。为了提高病变部位与正常组织间信号的对比度，约30%~40%的诊断需要使用磁共振成像造影剂。它是一类能缩短成像时间、提高成像对比度和清晰度、显示组织器官功能状态的诊断用药。下一代磁共振成像造影剂的设计目标将集中在对特定组织或器官具有选择性或靶向性、高弛豫性能和减少用药剂量等方面。本论文在此领域的研究内容可归纳如下： (1) 以多糖为载体的MRI造影剂 设计合成了阿拉伯半乳聚糖修饰的Gd-DTPA配合物(Gd-DTPA-CMAG-An)和葡聚糖修饰的Gd-DTPA配合物(Gd-DTPA-CMDn-Cyst)。通过体外弛豫时间测试和体内磁共振成像实验研究了Gd-DTPA-CMAG-An弛豫性能、器官选择性、体内滞留时间和代谢情况，结合体外稳定性综合评价了其应用于临床的可能性。研究结果表明，Gd-DTPA-CMAG-An配合物在水溶液中弛豫性能为Gd-DTPA的1.4倍左右，Gd-DTPA-CMAG-A2对肝脏信号的增强效果是Gd-DTPA的2.0倍左右，并且能在较长时间内产生良好稳定的增强效果。这与肝脏表面的去唾液酸糖蛋白受体的专一性识别有关。Gd-DTPA-CMAG-A2良好的肝脏选择性和肾脏代谢能力，有望成为有前景的肝脏选择性造影剂。通过小鼠MRI实验初步评价了Gd-DTPA-CMDn-Cyst配合物造影剂对血管信号的增强作用。Gd-DTPA-CMD4-Cyst对血管产生了良好的增强效果，并且能在较长时间内对血管产生良好稳定的增强，从而有充分的时间优化成像窗口获得理想的成像效果。但造影剂在体内的分布和代谢是一个非常复杂的过程，Gd-DTPA-CMD4-Cyst在血液中的滞留情况及能否用于血管造影仍需进一步的实验证实。 (2) MnNaY 型分子筛作为胃肠道MRI造影剂 离子交换法制备了Mn2+交换的NaY分子筛MnNaY，从对造影剂的一般要求出发，对其酸性水溶液中的稳定性和离子交换选择性、体外弛豫性能和体内成像等方面进行研究，并对器官的选择性及体内滞留时间和代谢情况进行了分析，从而对其应用于临床的可能性进行了探讨。研究结果表明，MnNaY悬浮液能长时间在较低的酸性条件下保持良好的稳定性，其弛豫效率高于目前临床所用造影剂Gd-DTPA，随Mn2+的含量在NaY分子筛中的增加(3.2%~5.2%)，弛豫效率反而降低。MnNaY (3.2% Mn)对胃部具有良好的增强效果，并且能在较长时间内产生良好稳定的增强效果，有利于获得理想的成像效果。它是一种比较好的潜在口服胃肠道造影剂。 (3) 甘草酸为载体的MRI造影剂 合成了甘草酸为载体的配合物GL-(A-Gd-DTPA)3，对其体外弛豫性能和体内成像等方面进行了研究，结果表明，其在水中的弛豫效率约为目前临床所用造影剂Gd-DTPA的1.4倍，体内成像表明它能在较长时间内对大鼠肝脏产生良好稳定的增强效果，这是由于肝(实质)细胞膜表面存在GL和GA受体，Gd-DTPA 以GL为载体后具有良好的趋肝性与肝细胞靶向性。 (4) 中性的Gd-DTPA双酰胺衍生物 合成了两种中性的Gd-DTPA双酰胺衍生物Gd-DTPA-BBA和Gd-DTPA-BtBA，其弛豫效率与Gd-DTPA相近，对肝脏和肾脏具有较好的增强效果，由于这两种配合物均为电中性化合物，这样配合物溶液的渗透压值与血液的渗透压值较接近，可能更易为生物体所接受。

生物活性有机锗及HPCPC双水相分离生物大分子的研究

本论文内容主要分为4个部分：“有机锗化合物抑制Maillard反应的研究”、“Ge-132对体外培养幼鼠胰岛细胞的作用研究”、“PEG／磷酸盐双水相体系中生物大分子分配的研究”和“HPCPC（High Performance Centrifugal Partition Chromatography，高效离心分配色谱）双水相体系对生物大分子分离的研究”。前两部分主要从有机锗化合物防治糖尿病及其并发症的代谢机理和细胞学角度进行研究，本文引入HPCPC和双水相体系分离生物大分子的技术，为进一步阐明有机锗化合物在Maillard反应过程中的作用机理：对双水相体系中生物大分子的分配及HPCPC在双水相体系中分离生物大分子也做了大量的基础性研究，为开发HPCPC的应用作出了有价值的探索工作。本论文的主要创新点归纳如下：一、有机锗化合物对Maillard反应的抑制作用：针对国际上有机锗发展的前沿课题，在国内首先开展了有机锗化合物对Maillard反应抑制作用的研究，取得了有价值的研究结果。1、在模拟体内的生理条件下，研究了不同浓度Ge-132对精氨酸、组氨酸、甘氨酸和缬氨酸对Maillard反应荧光峰强度的影响：不同类型的氨基酸Maillard反应产物结构上的差异和不同浓度有机锗对组氨酸糖化反应420nm处特征吸光度的影响。2、苯丙氨酸是侧链带有苯环的芳香族氨基酸，是一种具有弱的天然荧光的生物小分子，其荧光最大发射位置在281.6nm。由于aillard反应是葡萄糖和氨基酸的-NHR基发生的反应，其反应产物的特征荧光在440nm附近。这两类荧光的发射位置相差较远，相互之间没有影响，因此利用荧光法观察Phe在反应过程中自身的荧光变化和Ge-132对Phe的Maillard反应荧光产物的抑制情况。3、血清白蛋白是哺乳动物体内的重要蛋白质，可作为多种内源性、外源性物质的存储和转运蛋白，其Maillard反应已经被广泛重视，但较复杂的实验条件限制了它的研究。通过观测蛋白质Maillard反应产物特征荧光的变化是一有效的研究方法。BSA的内源性荧光是由肽链色氨酸和酪氨酸残基贡献的，其最大发射位置340nm左右。其Maillard反应产物的特征荧光在440nm附近，这两类荧光发射位置相差较远，基本上没有影响，因此能够通过荧光光谱研究BSA的Maillard反应荧光产物的情况。本文观测了Ge-132对BSA的Maillard反应荧光产物的抑制作用，同时还通过荧光法确定了一个文献中没有的新的反应位点。4、本文研究了具有更高水溶性的一类双有机锗化合物(HO)_2Ge(CHR_1CHR_2COOH)_2．2H_20抑制Maillard反应的特性，结果证明它比Ge-132具有更高的抑制作用，我们通过化合物的构效关系解释了上述作用的机制。5、本文研究了Tb(Ge-132)_3和Eu(Ge-132)_3两种含稀土的配合物对氨基酸、蛋白质Maillard反应的影响，观察了稀土离子对Maillard反应体系的影响，对实验现象作出了合理的解释。二、Ge-132对体外培养幼鼠胰岛细胞的作用为进一步考察有机锗对糖尿病的防治作用，我们与白求恩医大合作，首次观察了Ge-132对体外培养的幼鼠胰岛细胞结构和功能的影响，研究了不同剂量的含锗化合物对幼鼠胰岛细胞分泌胰岛素的作用，认为低浓度的Ge-132对胰岛细胞分泌胰岛素具有明显的促进作用。该部分内容为首次报导。三、PEG／磷酸盐双水相体系中生物大分子分配的研究双水相萃取TPE(Aqueous Two-Phase Extraction)具有下述优点：生物相容性好、界面张力低、能量低、易于工业规模的放大、可以进行连续操作等。本论文系统地研究了各种蛋白质在PEG／磷酸盐体系中的分离情况，如在各种pH条件下，从6.8到9.2，各种分子量的PEG，包括PEGl000，2000，5000，6000，10000，和20000和磷酸盐双水相体系的物化性质，以及对lysozyme（溶菌酶），BSA（牛血清白蛋白），HSA（人血清白蛋白），Hemoglobin（血红蛋白）在各种体系中的分配系数，探讨了各种因素对生物大分子分配的影响。四、HPCPC在双水相体系对生物大分子分离的研究由于荧光光谱法证实了Ge-132对牛血清白蛋白Maillard反应的抑制作用。但对于如何能够分离出糖化产物，达到进行定量表征的目的是我们研究的一个重要内容。九十年代初，由日本研制出一种色谱中新技术HPCPC。HPCPC与传统的液相色谱(LC)和高效液相色谱(HPLC)不同，不需要固体作为支持体。流动相和固定相分别为两种不相混溶的液体，通过离心力的作用使其中一相作为固定相保持在类似多级萃取器的微小分配槽中，另一相作为流动相流经固定相。HPCPC在双水相体系的应用是一种利用多级连续萃取从双水相中分离生物物质的方法它具有运行时间快、高效高选择性，流动相与固定相之间比例可以任意改变，并在任何pH值均可进行正向和反向操作并且实验室规模可一步直接放大到生产规模。它不仅可以作为一种分离的工具，而且也是一种研究生物萃取反应动力学机理，反映热力学与动力学之间相关性的重要方法。本论文中研究了常用的两种双水相体系，利用PEG6000／Dex20000／H_20对BSA和Maillard反应产生的糖化BSA进行了初步分离，取得了一些阶段性结论。另外，通过对各种条件的筛选，选择了具有代表性的lysozyme和BSA，BSA和血红蛋白(Hb)进行HPCPC色谱仪上的分离，研究了色谱分离条件如：转数、流速、pH等对分离效率及理论塔板数的影响，取得了一系列重要的结论。为工业上大规模的生物样品分离提供了重要的参数。