肥液浓度对单膜孔入渗NO-3-N运移特性影响的室内试验研究

该文通过室内入渗试验，研究了不同浓度的单膜孔肥液入渗NO^-₃-N的分布特性。研究表明：不同浓度的膜孔肥液入渗土壤NO^-₃-N浓度的湿润锋运移距离与土壤水分运动的湿润锋一致；肥液浓度越大，相同入渗时间的NO^-₃-N浓度锋运移距离越大，土壤剖面NO^-₃-N浓度最大值越大，相同深度处土壤NO^-₃-N浓度也越大。肥液入渗土壤NO^-₃-N浓度分布特征与湿润体深度符合分段函数模型。供水入渗过程中，NO^-₃-N浓度锋运移距离和浓度最大值均随时间的延长而增大；再分布过程中，NO^-₃-N浓度锋运移距离继续增大，而NO^-₃-N浓度最大值逐渐减小。     

实体水-虚拟水"二维三元"耦合流动理论基本框架

在变化环境下,区域水资源系统演变规律正在发生深刻变化。解决新形势下出现的水问题单单依靠传统的实体水资源规划、调度和调控手段还不够。虚拟水概念和理论的提出拓展了水文水资源的认知范畴,丰富了水问题的解决手段。然而,如何搭建虚拟水理论与传统水文水资源认知体系的统一框架,认识自然-经济-社会连续系统中水资源演化的新规律,目前学界还没有成熟统一的看法。该文首先提出了实体水-虚拟水耦合流动效应的基本理论框架,指出实体水-虚拟水耦合流动是现代环境下自然-经济-社会水资源系统呈现的新特征。其次,从文明进步和生产力发展角度,论述了人类社会水文水资源系统的演化历史,将水文水资源系统演进大体分为三个阶段:早期的实体水"一维一元"自然循环阶段,近现代的实体水"二元"水循环阶段和当前的实体水-虚拟水"二维三元"耦合流动阶段。最后,该文详细论述了实体水-虚拟水耦合流动过程的路径结构,并针对其流动过程和状态表征提出了定量表达方程,初步构建了实体水-虚拟水耦合流动基本理论框架。     

Influence of green manuring with Sesbania rostrata and Aeschynomene afraspera or urea on dynamics and uptake of nutrients by wetland rice

Nutrient concentrations in the soil and crop uptake from incorporated green manure and urea in flooded rice was studied in field experiments. Release of plant-available nitrogen (NH₄ ⁺-N) from green manure was slightly delayed compared with that from prilled urea (PU) because Sesbania rostrata L. and Aeschynomene afraspera L. released the N gradually after their decomposition, whereas N became available immediately after PU application. Exchangeable NH₄ ⁺-N concentration in soil peaked at 163 mg kg^–1 in the transplanted rice (TPR) and 198 mg kg^—1 in broadcast-seeded rice (BSR) at 0 and 1 week after PU application. Broadcast-seeded rice depleted NH₄ ⁺-N faster than did TPR because of the crop‘s vigorous growth in the former during the early stage. Soil solution NH₄ ⁺-N followed a similar trend to that of soil NH₄ ⁺-N. Incorporation of S. rostrata and A. afraspera increased the concentration of P, K⁺, Fe²⁺ and Mn²⁺ in soil solution more than did the application of PU. However, zinc concentration decreased in all treatments. Both PU and green manure increased the N status of the rice plants and enhanced the uptake of P, K, Fe, Mn and Zn by the rice crop. This suggests that application of green manures improves the uptake of these nutrients by the crop. The highest apparent N recovery was obtained with PU followed by green manure. Received: 11 November 1996     

The combined effects of enhanced UV-B radiation and selenium on growth, chlorophyll fluorescence and ultrastructure in strawberry (Fragaria × ananassa) and barley (Hordeum vulgare) treated in the field

The possible ameliorative effects of selenium (Se) addition to soil on the detrimental effects of enhanced UV-B radiation were tested on strawberry and barley during 4 months of field experiment in Kuopio, Central Finland. Control plants were exposed to ambient levels of UV radiation, using arrays of unenergized lamps. A control for UV-A radiation was also included in the experiment. Added Se, applied as H₂SeO₄, at the level of 0.1 mg kg⁻¹ soil (low dosage) and 1 mg kg⁻¹ soil (high dosage) increased Se concentrations in plants more than 10 and 100 times, respectively. After 4 months of exposure, strawberry and barley plants were harvested for biomass analysis. Chlorophyll fluorescence was measured using the Hansatech FMS2 fluorescence monitoring system. Leaf anatomy and ultrastructure were observed by light and transmission electron microscope. Several effects of UV and Se as well as their interaction were found, mostly for strawberry, but not for barley, indicating species-specific responses. Our results provided evidence that the high Se concentration in soil had no ameliorative effect but increased the sensitivity of strawberry to enhanced UV-B radiation in the field. Under ambient radiation, Se did not alter leaf growth of strawberry, whereas under UV-B radiation, the high Se addition significantly decreased leaf growth. Strawberry runner biomass was affected by the interaction of Se and UV. Under ambient radiation Se did not change dry weight of runners, but in combination with UV-A or UV-B radiation the high Se dosage decreased dry weight of runners by about 30%. Although the high Se concentration positively influenced on quantum efficiency of photosystem II (PSII) in strawberry leaves, it reduced runner biomass, leaf number and ratio of starch to chloroplast area. This suggests that the harmful effects of the high Se dosage on photosynthetic processes occurred as a result of changes in activity or/and biosynthesis of enzymes, rather than alteration of PSII. At the low concentration, Se effects were slight and variable.Although barley leaves accumulated higher Se concentrations than strawberry, there were no apparent changes in their growth, biomass or chlorophyll fluorescence due to Se effect either alone or in combination with UV-B. However, at the ultrastructural level, an enlargement in the peroxisome area was found due to combination of UV radiation with Se, suggesting the activation of antioxidative enzymes, possibly catalase. Decrease in mitochondrial density in barley cells in response to Se might be attributed to alteration of mitochondrial division. Increase in the proportion of cells with cytoplasmic lipid bodies due to combined effect of UV-B and Se indicated the alteration of lipid metabolism and the acceleration of cell senescence in barley. Main UV-B effects were found, mostly at the tissue and ultrastructural level in strawberry, but not in barley, indicating species-specific susceptibility to enhanced UV-B radiation. UV-B-treated strawberry plants developed marginally thinner leaves with reduced ratio of starch to chloroplast area in their cells, suggesting negative influence of UV-B on photosynthetic processes.     

用~3H-TdR研究混合重金属对鲫鱼DNA合成的影响

应用3 H 胸腺嘧啶核苷 ( 3 H TdR)示踪法研究混合重金属对鲫鱼 (Carassiusaura tus)遗传毒性的影响。结果表明 ,最佳取样时间为注射3 H TdR后 6h。鱼体各组织对混合重金属的毒性反应呈现双向效应 ,即低浓度时 ,表现出损伤、修复作用 ;高浓度时 ,DNA合成受到抑制。鱼卵、鱼鳃对重金属最敏感 ,损伤浓度为 0 0 773mg L ;而大脑对混合重金属耐受性最强。DNA损伤修复作用和DNA合成作用都存在剂量效应 ,随着暴露时间的延长 ,毒性作用增大。鱼体各组织对重金属的毒性反应可由DNA损伤修复变成合成抑制。经过 72h暴露后 ,3 H TdR在肝脏、鱼鳃、鱼卵中掺入量约低于对照的 5 0 %。     

三角帆蚌Rab3 cDNA全长克隆及其原核表达

根据三角帆蚌消减杂交cDNA文库获得的EST序列,运用cDNA末端快速扩增（rapid amplification of cDNA ends,RACE）技术获得三角帆蚌Rab3基因的全长cDNA序列（GenBank登录号为HQ190954）。序列全长1707 bp,开放阅读框666 bp,编码221个氨基酸,5’端非编码区为158 bp,3’端非编码区为883 bp。软件推测其编码蛋白相对分子量为24.92 KDa。NCBI Blastp进行氨基酸序列同源性分析表明,与居蟹皮海绵（Suberites domuncula）的Rab-3like（SdRab3）氨基酸相似性最高,为64%,构建进化树的结论也是先与居蟹皮海绵的Rab3-like（SdRab3）聚为一支。根据获得的Rab3基因cDNA全长序列,设计特异性引物扩增获得完整开放阅读框序列,并将已克隆到的三角帆蚌Rab3开放阅读框定向插入原核表达载体PQE-His质粒中,转化大肠杆菌BL21（DE3）。在30℃,5 h,1 mM IPTG的诱导条件下,Rab3蛋白得到高效表达,重组菌体经裂解和SDS-PAGE电泳分析,发现一条26 kDa左右特异的蛋白表达条带,其表达量约占菌体总蛋白30%。Western-blot检测表明,在健康组和病变三角帆蚌肝脏中,Rab3蛋白与β-actin的表达量比值分别为0.438和0.580。这一结果说明,Rab3基因在三角帆蚌经病原菌侵染后,表达量上调,且已有研究表明Rab3有通过调节中性粒细胞的胞吐作用来抵抗细菌侵入、防止机体感染的功能,从而初步推测三角帆蚌Rab3蛋白可能与三角帆蚌瘟病有关。     

冷诱导下毛百合甘油-3-磷酸酰基转移酶活性变化及其基因保守区的克隆

探讨了野生毛百合甘油-3-磷酸酰基转移酶活性在冷胁迫下的变化,用简并引物扩增了甘油-3-磷酸酰基转移酶基因保守区序列的结果表明,该保守区段长744 bp,推测编码247个氨基酸.在GPAT氨基酸序列中存在1个高度保守的区域(WIAPSGGRDRP),在NCBI上经过BLASTp比对分析,发现这段保守区序列为LPLAT基...     

HPLC同时测定花生壳中绿原酸3,4—二咖啡酰奎尼酸和木犀草素

建立了同时测定花生壳中绿原酸、3,4-二咖啡酰奎尼酸和木犀草素3种有效成分含量的反相高效液相色谱方法。采用Kromasil C18柱(200 mm×4.6 mm,5μm),乙腈和0.1%甲酸水溶液梯度洗脱,流速为1.0 mL/min,检测波长340 nm,柱温27℃。在该色谱条件下,绿原酸、3,4-二咖啡酰奎尼酸和木犀草素的质量浓度分别为3.75~60μg/mL(R2=0.999 9),3.63~58.08μg/mL(R2=0.999 9),17.25~276μg/mL(R2=0.999 7)内与色谱峰面积呈现良好的线性关系,平均加标回收率(n=5)为121.6%,97.79%,124.35%,RSD分别为0.71%,1.49%,0.44%。该分析方法快速准确、重现性好,可应用于花生壳资源产业开发中质量标准的建立和完善。     

免疫亲和层析法分离鸡补体C3d蛋白研究

利用抗鸡C3 21肽抗体制备免疫亲和层析柱,对鸡补体C3d进行了分离,并采用间接酶联免疫吸附实验(间接ELISA),对洗脱液中的C3d组分进行了检测,以SDS-PAGE电泳方法对分离到的C3d进行了检测。结果表明,利用亲和柱层析能够分离得到纯度较高的C3d蛋白,为鸡血清中C3d的提取纯化提供了较为简便的方法。