山羊胎盘肽对幼犬免疫功能和抗氧化功能的影响

将24只健康幼犬随即分成4组,一个对照组(n=6),3个实验组:小剂量(1mg/kg.bw)胎盘肽(Goat placenta peptide,GPP)组(n=6)、中剂量(2mg/kg.bw)胎盘肽组(n=6)、高剂量(4mg/kg.bw)胎盘肽组(n=6)。在口服羊胎盘肽的前1 d和连续口服羊胎盘肽10 d后的第1 d各组采血样一次,测定外周血白细胞数、ANAE 淋巴细胞百分率、血清球蛋白含量、血清溶菌酶活性、血清总抗氧化能力、血清谷胱甘肽过氧化物酶活性、血清超氧化物歧化酶活性及丙二醛含量。结果表明:连续给药10 d后实验组幼犬血液白细胞总数、ANAE 淋巴细胞百分率、血清球蛋白含量、血清中溶菌酶活性与给药前相比均明显增加,并且中剂量组、高剂量组与给药前相比差异显著或极显著(P<0.05,P<0.01)。同时犬血清总抗氧化能力、血清谷胱甘肽过氧化物酶活性及超氧化物歧化酶活性均较给药前相比有所增强,血清丙二醛含量与给药前相比明显减少,并且中剂量组、高剂量组与给药前相比差异显著或极显著(P<0.05,P<0.01)。实验结果提示中剂量(2mg/kg.bw)、高剂量(4mg/kg.bw)羊胎盘肽可提高幼犬的免疫功能和抗氧化能力,从而提高幼犬的抗病防病能力。     

Response of mycorrhizal, rhizosphere and soil basal respiration to temperature and photosynthesis in a barley field

The mycorrhizal, rhizosphere and basal components of soil respiration were partitioned in a barley field experiment with the main objective of determining the controlling effects of photosynthetic activity and temperature on soil respiration sources. Micro-pore meshes were used to create both root and mycorrhiza-free soil cores over which collars for soil respiration measurements were inserted. Differences between mesh treatments were used to determine the contribution of each component. With a focus on the growing season, we analyzed the response of respiration sources to photosynthesis, temperature and moisture, as well as changes in microbial biomass, mineral nitrogen and carbon-nitrogen ratios responding to treatment and time of year. Results gave clear differences between sources in their response to both temperature and photosynthetic activity and showed that several processes are involved in determining respiration rates as well as apparent temperature relations. In particular, the respiration of arbuscular mycorrhizal hyphae was seen to be a significant amount of root derived carbon respiration (25.3%) and consequently of total assimilated carbon (4.8%). This source showed a stronger response to photosynthetic activity than the rhizosphere component (r²=0.79, p<0.001 and r²=0.324, p=0.53, respectively). Q₁₀ values—the increase in respiration rates with a 10 °C increase in temperature—changed seasonally and showed temperature relations being dependent on the presence of mycorrhizal and rhizosphere respiration sources, as well as on plant development. Respiration from mycorrhizal hyphae and the rhizosphere showed no response (r²=0, p<0.99) or low response (r²=0.14, p<0.01) to temperature, respectively. We conclude that the potential importance and controls of mycorrhizal fungi respiration in croplands are comparable to those observed in other ecosystems, and that temperature response curves should be carefully interpreted given that substrate availability and plant dynamics strongly regulate respiration rates in ecosystems.     

Carbon dioxide and energy flux partitioning between the understorey and the overstorey of a maritime pine forest during a year with reduced soil water availability

Carbon dioxide, water vapour and energy fluxes were measured above and within a maritime pine forest during an atypical year with long-lasting reduced soil water availability. Energy balance closure was adequately good at both levels. As compared with what is usually observed at this site the ecosystem dissipated less energy via latent heat flux and more via sensible heat flux. The understorey canopy was responsible for a variable, significant component of the whole canopy fluxes of water vapour and carbon dioxide. The annual contribution of the understorey was 38% (154 mm) of the overall evaporation (399 mm) and 32% (89 mm) of the overall sensible heat flux (274 mm). The participation of the understorey reached 45% of the overall evaporation and 30% of the daytime overall assimilation during significant soil water deficit periods in summertime. Even during winter, understorey photosynthesis was consistent as it compensated soil and understorey respiration. The ecosystem behaved as a sink of carbon, with a negative annual carbon budget (−57 g C m⁻²). However, due to high soil water deficit, the annual ecosystem GPP was 40% less than usually observed at this site. This budget resulted from a sink of −131 g C m⁻² for the overstorey and a source of +74 g C m⁻² for the understorey. Moreover, on an annual basis the overstorey layer contributed to almost two-thirds of the ecosystem respiration. Finally, the effect of long-lasting soil water deficit on the maritime pine forest was found more important than the effect of the heat wave and drought of summer 2003.     

绞股蓝多糖对D-半乳糖致衰老小鼠肝脏抗氧化能力的影响

【目的】 探究绞股蓝多糖(Gynostemma pentaphyllum polysaccharides, GPP)对D-半乳糖(D-galactose, D-gal)致衰老小鼠肝脏抗氧化能力的影响。【方法】 60只4周龄SPF级昆明小鼠随机分为6组(雌雄各半): 空白对照组(Control)、模型组(D-gal)、阳性对照组(Vc)及绞股蓝多糖低(50 mg/kg)、中(100 mg/kg)、高(200 mg/kg)剂量组(GPP-L、GPP-M和GPP-H), 每组10只。采用生物化学、酶联免疫吸附及组织学技术等方法分别对各试验组小鼠的体重及增重变化、肝脏指数、血清总抗氧化能力(T-AOC)水平、肝脏超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化氢酶(CAT)活性、活性氧(ROS)、丙二醛(MDA)含量及肝脏组织形态和肝索面积比进行测定分析。【结果】 各组小鼠体重均呈增长趋势, 增重均呈下降趋势, 其中GPP-M组小鼠体重低于其他各组, 增重最少; GPP各剂量组肝脏指数、血清T-AOC水平均高于D-gal组; GPP各剂量组的小鼠肝脏组织SOD水平与D-gal组相比均无显著差异(P>0.05)。GSH-Px、CAT活性水平与D-gal组相比均有所增强, 其中GPP-M组小鼠肝脏中GSH-Px活性显著高于D-gal组(P<0.05);GPP-L组小鼠肝脏中CAT活性显著高于D-gal组(P < 0.05), ROS、MDA含量均显著低于D-gal组(P<0.05)。HE染色发现, D-gal组胞浆嗜酸性增强, 肝细胞之间连接松散, 肝血窦扩张明显, 而GPP各组肝脏组织结构均有所改善, GPP-M与GPP-H组改善较明显; GPP-H组肝脏肝索面积占比与空白对照组和阳性对照组相当, GPP-M和GPP-H组肝脏肝索面积占比与GPP-L组相比显著增加(P<0.05)。【结论】 GPP可以有效提高D-gal致衰老小鼠肝脏的抗氧化能力, 从而达到延缓衰老的作用, 其中GPP-M(100 mg/kg)组对D-gal致衰老小鼠肝脏抗氧化效果明显。     

基于作物模型模拟年际生物量变化的 冬小麦干旱监测研究

选择关中平原地区冬小麦为研究对象,在对农业技术转移决策支持系统(DSSAT)中的CERES-Wheat模型进行标定的基础上,根据距平的方法分析了模型模拟的冬小麦生物量的年际变化情况.结果表明:生物量距平为正值时,未发生旱情或旱情不明显;生物量距平为负值时,发生了干旱.据此建立了基于生物量距平的干旱监测模型.通过气象网站的降水量资料对该研究区域2000-2009年每年4月下旬的单点干旱监测结果进行验证,结果表明生物量距平与最近2旬至5旬的累计降水量距平的相关性较高,证实了应用该模型进行干旱监测的可行性和近实时性.将该模型与2000-2009年MODIS每8天的GPP产品相结合,得到了干旱的区域分布结果,结果表明:关中平原在2000、2003年和2007年4月下旬时发生干旱,在其余研究年份4月下旬时未出现旱情.     

灵芝肽多糖生物活性初探

从人工培养的灵芝菌丝体中分离纯化得到灵芝肽多糖(简称GPP)。经测定,GPP分子量为140000,单糖组成为木糖、葡萄糖、半乳糖及半乳糖醛酸。GPP分子中含蛋氨酸、赖氨酸等13种氨基酸。动物实验表明,GPP能显著提高小鼠腹腔吞噬细胞的吞噬能力,增强体液免疫和红细胞免疫功能,并能提高红细胞中超氧化物岐化酶(SOD)的活性。     

河北坝上地区绿水时空变化及其驱动因素研究

河北坝上半干旱农牧交错带是首都西北重要的生态屏障。绿水在维持坝上半干旱生态系统稳定、保障京津冀地区生态环境安全中发挥着重要作用,但绿水资源的时空分布及其驱动因素还缺乏定量理解。本文基于GLASS蒸散产品,定量分析了2001—2015年河北坝上(康保县、沽源县、尚义县、张北县)县域尺度的绿水时空变化特征,通过线性变化系数、相关系数、贡献率方法评估了绿水变化对气温、降水、净辐射(Rn)、总第一性生产力(GPP)以及土地利用的响应规律,以期为坝上地区"首都水源涵养功能区和生态环境支撑区"建设、水资源高效利用提供科学依据。研究结果表明:1)2001—2015年坝上4县的绿水量总体呈下降趋势,多年平均绿水量为371.11 mm;绿水量季节变化明显,表现为夏季春季秋季冬季。2)绿水量由西北至东南递增,其中沽源县绿水量最大,康保县绿水量最小;研究期间21.2%的区域绿水量呈增加趋势,78.8%的区域呈减少趋势。3)绿水与降水、GPP呈正相关关系,与气温和净辐射呈负相关关系,各影响因子对绿水变化的贡献率排序为GPP气温降水R_n,GPP的贡献率高达51%。4)研究区内各土地利用类型绿水量表现为林地草地耕地建设用地。绿水量变化趋势受土地利用变化影响显著,土地利用更直接地影响绿水的空间分布。     

水利工程对年楚河流域农业水资源利用效率和作物生产力的影响

水库是水资源调配的主要举措之一，影响着流域生态水文过程和农业生产。满拉水库作为"西藏第一坝"，其兴建与运行对青藏高原的水资源管理与农业发展都具有重要意义。该研究以满拉水库所在的年楚河流域为例，结合SWAT水文模型与遥感影像，分析了满拉水库蓄水量变化。基于农田水量平衡原理，利用植被界面过程模型（Vegetation Interface Processes，VIP）模型估算了水库调度下流域耕地总初级生产力（Gross Primary Productivity，GPP）的变化。采用岭回归定量分析了人类活动（水库灌溉）、气候因子（气温、降水、辐射）以及大气CO2浓度对流域GPP变化的影响。结果表明：1）自满拉水库修建以来，年楚河径流量减少3.78×109 m3/a，其中，66%的水量经由水库调蓄补给灌溉。2）2000-2019年，流域内耕地多年平均GPP在143～852 gC/(m2·a)之间，90%以上耕地的GPP呈上升趋势，平均上升速率为5.3 gC/(m2·a2)，其中67%以上的区域上升趋势显著（P<0.05）。3）灌溉量增加和大气CO2浓度上升对耕地GPP上升的贡献率分别为43.9%和25.1%，是GPP增加的主导因素。满拉水库的修建不仅显著改变了流域的生态水文过程，更提高了下游农业灌溉水平和作物生产潜力，研究结果对年楚河流域水资源配置及农业规划具有科学参考价值。