氨基酸缺乏诱导细胞自噬的哺乳动物雷帕霉素靶蛋白复合体C1信号通路机制研究进展

自噬是机体维持自身稳态的一种重要生理活动,当体内氨基酸或葡萄糖等营养缺乏时,细胞会启动自噬。自噬受到多种信号通路的调节,哺乳动物雷帕霉素靶蛋白复合体C1(m TORC1)信号通路是其中重要的一条,它可以使自噬相关基因13(Atg13)磷酸化,抑制自噬起始。本文将围绕近年来报道的氨基酸缺乏诱导细胞自噬的m TORC1信号通路,包括小G蛋白、腺苷酸活化蛋白激酶(AMPK)、微小RNA(miRNA)、氨基酰-tRNA合成酶在其中的作用等研究进展进行综述。     

砷胁迫对黑麦草根系形态及养分吸收的影响

黑麦草对重金属具有较强的耐性和富集能力,是一种良好的植物修复材料。为探究砷(As)胁迫下黑麦草的根系形态以及根系养分吸收特征,采用盆栽试验研究了100mg·kg~(-1) As胁迫下,多年生黑麦草(Lolium perenne)和一年生黑麦草(L.multiflorum)的根系形态和营养元素吸收情况,并分别对As吸收与根系形态和养分吸收做相关性分析。结果表明,多年生黑麦草总根长和总根表面积受抑制程度更加明显,分别降低47.6%和46.8%;多年生黑麦草根系As吸收能力是一年生黑麦草的1.2倍。As胁迫促进两种黑麦草根系对N、P、K、Mn元素的吸收,二者相比,多年生黑麦草根系吸收N、P、K三种大量元素受影响更大,而一年生黑麦草根系吸收微量元素Mn受影响更大。总体上看,多年生黑麦草的根系形态和养分吸收能力对As胁迫更加敏感。     

呼伦贝尔草甸草原群落特征对不同放牧制度的响应

对呼伦贝尔草甸草原划区轮牧和自由放牧两种放牧制度植物群落特征进行了比较研究.结果表明:羊草的密度在自由放牧区显著高于划区轮牧区,高度、盖度不同放牧处理之间差异不明显;贝加尔针茅高度和盖度轮牧区显著高于自由放牧区,密度对照区显著高于两放牧处理区;苔草高度、盖度和密度自由放牧区高于划区轮牧区.Margalef丰富度指数、S...     

基于无线传感网络隧道亮度信号采集系统的研究

亮度信号是高速公路隧道节能照明控制系统必须检测的物理量。本文基于zigbee的技术特点,设计了一款基于无线传感网络的隧道亮度信号采集系统。系统的传感器节点负责亮度信号的采集,经CC2530处理发送,通过逐级跳转的方式把数据传输到协调器。协调器通过RS232串口与灯具控制器通信,以此实现对亮度信号的实时采集和可靠性传输。通过实验表明,该系统达到了设计的目的,并适用于高速公路隧道节能照明控制系统。     

荒漠草原不同利用条件下短花针茅贮藏性碳水化合物的对比

在不同利用条件下(休牧40d、休牧50d、休牧60d、自由放牧、禁牧)对荒漠草原短花针茅贮藏性碳水化合物进行了动态监测,并采用最优母序列关联分析探讨了荒漠草原不同利用条件下短花针茅贮藏性碳水化合物的年度内及年际间的差异,结果表明:试验期年度内和年际间不同利用条件下短花针茅还原糖含量波动均较大;休牧40d短花针茅总糖含量较高,休牧60d次之,休牧50d短花针茅总糖含量较低,但还原糖含量较高;还原糖与总糖比值的变化较还原糖含量、总糖含量稳定;休牧50d有利于短花针茅植物种群生长发育和种群繁衍.     

蜂蜜中果糖含量近红外光谱试验研究

以68份蜂蜜样品为材料,利用傅立叶变换近红外光谱技术（NIR）结合偏最小二乘法（PLS）,建立了蜂蜜中果糖含量的近红外光谱数学模型,并对模型预测结果进行评价。结果表明,选择11065．36cm^-1～7857．90cm^-1波数范围内的光谱,进行SG预处理方法,用8个主成分建立的蜂蜜果糖含量模型效果最好,模型相关系数、校正均方差和预测均方差分别为0．9259、1．21和1．64。该方法具有快速、准确、成本低等特点。     

Nuclear Replacement of In Vitro‐Matured Porcine Oocytes by a Serial Centrifugation and Fusion Method

The objective of the present study was to establish a method for nuclear replacement in metaphase‐II (M‐II) stage porcine oocytes. Karyoplasts containing M‐II chromosomes (K) and cytoplasts without chromosomes (C) were produced from in vitro‐matured oocytes by a serial centrifugation method. The oocytes were then reconstructed by fusion of one karyoplast with 1, 2, 3 or 4 cytoplasts (K + 1C, K + 2C, K + 3C and K + 4C, respectively). Reconstructed oocytes, karyoplasts without fusion of any cytoplast (K) and zona‐free M‐II oocytes (control) were used for experiments. The rates of female pronucleus formation after parthenogenetic activation in all groups of reconstructed oocytes (58.2–77.4%) were not different from those of the K and control groups (58.2% and 66.0%, respectively). In vitro fertilization was carried out to assay the fertilization ability and subsequent embryonic development of the reconstructed oocytes. The cytoplast : karyoplast ratio did not affect the fertilization status (penetration and male pronuclear formation rates) of the oocytes. A significantly high monospermy rate was found in K oocytes (p < 0.05, 61.6%) compared with the other groups (18.2–32.8%). Blastocyst formation rates increased significantly as the number of the cytoplasts fused with karyoplasts increased (p < 0.05, 0.0–15.3%). The blastocyst rate in the K + 4C group (15.3%) was comparable with that of the control (17.8%). Total cell numbers in both the K + 3C and K + 4C groups (16.0 and 15.3 cells, respectively) were comparable with that of the control (26.2 cells). Our results demonstrate that a serial centrifugation and fusion (Centri‐Fusion) is an effective method for producing M‐II chromosome transferred oocytes with normal fertilization ability and in vitro development. It is suggested that the number of cytoplasts fused with a karyoplast plays a critical role in embryonic development.     

Biomechanical Comparison of the Trocar Tip Point and the Hollow Ground Tip Point for Smooth External Skeletal Fixation Pins

Objective —To compare the insertional characteristics of external fixator pins with hollow ground (HG), modified HG, and trocar (T) points.
Study Design —An acute, in vitro biomechanical evaluation.
Sample Population—Thirteen radii from canine cadavers.
Methods —A total of 16 T-tipped and 16 HG-tipped pins were inserted into 8 canine radii. Ten pins of each modification of the HG tip (length of the cutting edge reduced by 0.127 mm and 0.254 mm, respectively) were inserted into another five radii. All pins were inserted with low-speed power drilling and 80 N drilling load. Differences between peak tip temperature, drilling energy, and pullout force were determined for each pin type at both diaphyseal and metaphyseal locations.
Results —HG-tipped pins showed a 40% lower tip temperature in diaphyseal bone, a 25% reduction in drilling energy in diaphyseal bone, and a reduction of pullout force in both diaphyseal (65%) and metaphyseal (50%) bone compared with T-tipped pins. HG 0.254-mm pins generated higher tip temperatures and had greater pullout than HG pins in diaphyseal bone.
Conclusions —The HG tip was a more efficient design; however, the reduction in pullout force suggests that, because a better hole was drilled, radial preload is reduced. Reduction of the cutting edge by 0.254 mm increased the pullout force but also increased the temperatures.
Clinical Relevance —Thermal and microstructural damage are reduced by the HG tip, but pin-bone interface stability is also compromised. The use of a tip with 0.254 mm reduction in the cutting edge may optimize the biological and mechanical factors at the pin-bone interface.     

阿拉善荒漠草地生态危机及其治理对策

综述了阿拉善地区生态危机的现状 ,并根据多年来生态治理的经验和成果 ,提出了以改善生态环境为目标、草原建设为重点、综合开发为手段 ,坚持环境治理与农牧业生产并重的治理原则与方法     

依普黄酮对笼养蛋鸡骨质疏松症骨组织病理变化的影响

本试验选用200只24周龄健康海蓝褐蛋鸡,随机分为4组:对照组(基础日粮中含钙3.55%)、低钙组(日粮含钙1.27%)、试验Ⅰ组(8mg依普黄酮/kg低钙日粮)和试验Ⅱ组(20mg依普黄酮/kg低钙日粮),观察依普黄酮对笼养蛋鸡骨质疏松症骨组织病理变化的影响。结果显示,与低钙组相比,试验Ⅰ、Ⅱ组骨髓腔面积分别显著下降7.81%(P0.05)和10.26%(P0.05),骨皮质平均厚度分别显著升高23.78(P0.05)和27.60(P0.05),并且骨小梁增厚、变密,骨陷窝变浅,成骨细胞增多,破骨细胞减少。结果表明,低钙日粮中添加依普黄酮能显著改善蛋鸡骨质疏松症的临床症状,与其促进成骨细胞生成,抑制破骨细胞活性,使其骨量增加,骨结构得到改善密切相关。