北京鸭胰液分泌昼夜变化规律研究

为了研究北京鸭的胰腺外分泌的昼夜变化规律,通过肠-胰(第一胰管)瘘管,全天分8个时间段收集胰液,分别测定胰液的分泌量、胰液pH值、总蛋白含量、HCO3-浓度、胰蛋白酶、胰脂肪酶和胰淀粉酶活性。结果显示北京鸭的胰液是一种具有较大缓冲容量的缓冲溶液,为各种消化酶提供了适合的酸碱环境。胰液中的各种消化酶的变化规律各异,和饲喂之间的关系不明显。     

Potato yield gaps across the rainfed Yin-mountain Hilly Area of China

Yin-mountain Hilly Area is one of the ideal regions for potato (Solanum tuberosum) production in China. However, potato yield is severely limited as a result of rain-fed crop mode due to water deficiency, as well as an inadequate farming practices. In this study, yield gaps were determined by using attainable yield (Ya) as a benchmark under optimized management practices, i.e., micro-ridge and side planting with plastic-mulching (MS), and flat planting with plastic-mulching (PM). The yields under MS and PM modes are defined as Ya1 and Ya2, respectively. Under the same field with MS and PM modes but different densities and fertilizer usages and so on, it was defined as simulated farmers' practices. The yield of simulated farmers' practices (Yf1) reached 57.3 and 69.6% of Ya1 and Ya2, respectively, while the average yield of 298 randomly surveyed farmers (Yf2) reached only 37.0 and 47.8% of Ya1 and Ya2 for rain-fed potato, respectively. The gaps of water use efficiency exhibited similar pattern. Further analysis shows that improper measures in rainwater conservation and accumulation, and other management practices contributed to 18.5, 18.2, and 42.6% of yield gap between Ya1 and Yf2. Improper nutrition management, including overuse of nitrogen and the deficiency of phosphorus and potassium supplication, was one of the important reasons of yield gap. The results indicate the possibilities of increasing rain-fed potato yields by optimized water and fertilizer managements in the Yin-mountain Hilly Area.     

羟基蛋氨酸铜中铜含量的测定

分别用PAN、二甲酚橙、紫脲酸铵作为指示剂,研究了EDTA配位滴定法测定羟基蛋氨酸铜螯合物中铜含量的方法,标准偏差均小于0.2%,相对标准偏差小于0.6%。结果表明,EDTA配位滴定法测定羟基蛋氨酸铜中铜含量,操作过程简单、方便,分析结果重现性好、准确度高,且三种指示剂均可用于铜的测定,其中紫脲酸铵最好,终点变色敏锐。本法可用于不同工艺所合成的羟基蛋氨酸铜中铜含量的测定。     

镰孢属李瑟组研究──促进李瑟组产孢的植物组织培养基

研究了采用常规方法灭菌的植物组织培养基，结果表明，在所试验的３０种植物组织培养基中，矢车菊、石竹和茶叶３种植物组织培养基能促进李瑟组镰孢产生典型的大孢子，小孢子和产孢细胞，可作为鉴定用培养基。     

水锤泵进水系统的试验与分析

着重对水锤泵的进水管直径,倾角及管长进行试验分析,从而提高了水锤泵的提水效率,增强了其适用性。     

鱼肠道弧菌免疫检测方法的研究

采用灭活的鱼肠道弧菌作为抗原,制备兔抗血清,建立了鱼肠道弧菌的间接荧光抗体检测技术(indirect im-munofluorescence assay test,IFAT)、Western-blotting免疫印迹检测技术。IFAT结果显示阳性信号覆盖整个菌体,明亮,清晰,荧光信号呈长弧形且两端钝圆,与鱼肠道弧菌形状一致。Western-blotting结果显示共10条蛋白带发生免疫反应,其中6条蛋白带结果较清晰,显示出较强的特异性免疫反应,阴性对照组无条带。IFAT和Western-blotting结果说明所建立检测方法能够准确、快速的检测出鱼肠道弧菌。     

短肢剪力墙设计在新高规中的变化

根据实际设计经验,简单阐述2010年版高规的短肢剪力墙在高层建筑结构设计中的注意事项以及相对2002年版高规的不同。2010年版高规规定不论是否短肢剪力墙多少,所有短肢剪力墙都要按短肢剪力墙设计。对普通剪力墙结构而言,2010年版高规更明确、适用,安全。     

Effects of VA mycorrhizae and Frankia dual inoculation on growth and nitrogen fixation of Hippophae tibetana

Through biological inoculation technology, the joint symbiosis of Tibetan seabuckthorn (Hippophae tibetana) in pure culture was identified and the effects of dual inoculation with Frankia and mycorrhizal fungi on the host plants in pot cultures were investigated. The results obtained from the comparative study showed that H. tibetana could form nodules and VA mycorrhiza both in pot and pure cultures. VA mycorrhizae and Frankia can stimulate the growth and the nitrogen fixation ability of host plants, respectively, yet the stimulation of the dual inoculation on the growth and nitrogen fixation ability of the host plants was more significant (p<0.05): stronger nitrogen-fixing ability, higher VA mycorrhizal development and better growth of seedlings in VAH and HR16 dual inoculation.     

A new approach for tracking seed dispersal of large plants: soaking seeds with 15N-urea

Context

Although various tracking methods have been used in many ecosystems to investigate seed dispersal and seedling recruitment, it is still difficult to measure seed dispersal patterns due to methodological challenges in tracking seed movement away from parent trees and in finding the locations of seedlings.

Aim

Here, we aimed to develop a new approach to track seed dispersal by animals in the field.

Methods

Our approach involves soaking seeds directly into ¹⁵N-urea solutions with different dosages to enrich them isotopically. This new method is expected to create a reliable differentiation between the enriched seeds and natural ones and consequently between the corresponding seedlings.

Results

We showed that acorns of Quercus variabilis and Cyclobalanopsis glauca and seeds of Pinus koraiensis soaked in ¹⁵N-urea solutions were successfully enriched. We did not find that δ ¹⁵N value of seeds was a linear function of ¹⁵N-urea soaking duration. However, with high urea dosage and extending soaking duration, the δ ¹⁵N values in seedlings of Q. variabilis and P. koraiensis were higher than those of normal plants. As expected, ¹⁵N isotope was significantly diluted in the growing seedlings germinated from ¹⁵N-enriched seeds. Using the ¹⁵N-urea soaking method, we successfully located five seedlings of Q. variabilis germinated from the enriched acorns in the field.

Discussion

The ¹⁵N-urea soaking technique is powerful in tracking seed dispersal and seedling recruitment. This new method solves some of the problems inherent in traditional methods for tracking secondary seed dispersal and could further improve the study of seed dispersal ecology.     

Genetic diversity of sea buckthorn (Hippophae rhamnoides) populations in northeastern and northwestern China as revealed by ISSR markers

As a N₂-fixing tree species, sea buckthorn (Hippophae rhamnoides) is well adapted to arid regions and is utilized for multiple purposes in China. Current knowledge of genetic variability of H. rhamnoides is limited in terms of rangewide distributions. Eleven natural populations of sea buckthorn in northeastern and northwestern China were analyzed to detect genetic variation among and within populations, by use of ISSR (inter-simple sequence repeats) markers. Using eight primers, 207 polymorphic loci were observed, ranging in size from 250 to 2500 bp. The coefficient of gene differentiation (Gst = 0.0679) showed that the total molecular variance of 11 populations was mainly existed within populations. The genetic variation within and among the 11 populations was 93.21 and 6.79%, respectively. No significant correlation between genetic and geographic distances of the populations was found using ISSR markers. Our study provides a population-level genetic profile for further investigation and conservation of genetic diversity of sea buckthorn.