Analysis of zein by matrix-assisted laser desorption/ionization mass spectrometry

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS) was used to analyze the protein composition of corn prolamine (zein). Mass spectra were obtained from commercial zein and zein extracted with aqueous 2-propanol and aqueous ethanol from consumer corn meal. For the commercial zein, three major zein fractions with m/z 26.8k, 24.1k, and 23.4k were clearly seen with two minor fractions (m/z 14.5k and 20.4k) also present. As compared with the results from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), these three fractions were identified as alpha-zeins (24.1k and 23.4k combined as Z19; 26.8k as Z22). When extracted with 55% aqueous 2-propanol, three alpha-zein fractions with m/z 26.8k, 24.1k, and 23.4k were predominant. When extracted with ethanol, extraction temperature had an effect on the final products. When extracted with 75% aqueous ethanol at room temperature, alpha-zein and some 17-18k species were observed, whereas at 60 degrees C, a small amount of delta-zein was also present. Comparison of the MALDI/MS results with SDS-PAGE and gene sequence analysis shows that the MALDI/MS method is superior to SDS-PAGE in having higher resolution and mass accuracy.     

Impacts of methamidophos on the biochemical,catabolic, and genetic characteristics of soil microbial communities

Methamidophos is an organophosphate pesticide with high toxicity and may significantly affect soil microbes. However, the magnitude of this effect is unclear. We examined the effect of low and high inputs of methamidophos on the structure of the soil microbial community, and the catabolic activity and the genetic diversity of the bacterial community using the polyphasic approaches of microbial biomass, phospholipid fatty acids (PLFAs), community-level catabolic profiles (CLCPs), and amplified ribosomal DNA restriction analysis (ARDRA) patterns. Our results indicated that high methamidophos inputs significantly reduced total microbial biomass carbon (C_mic) and fungal biomass, but increased Gram-negative bacteria with no significant effects on the Gram-positive bacteria. Interestingly, CLCPs patterns showed that high methamidophos inputs also significantly improved the catabolic activity of Gram-negative bacteria. The ARDRA pattern showed that the genetic diversity of the bacterial community decreased under chemical stress. Furthermore, changes in the microbial parameters examined were less significant under low inputs than high inputs of methamidophos, suggesting a dosage effect of methamidophos on the microbial community. Our results provide the first evidence that methamidophos differentially affected components of the soil microbial community through inhibiting fungal growth but enhancing the biomass and catabolic activity of Gram-negative bacteria.     

环渤海低平原区土壤安全容盐潜力评价

该文通过环渤海低平原区的土壤安全临界容盐潜力和最大容盐潜力分析,为保障土壤安全和粮食作物安全下的咸水灌溉提供科学依据。通过实验室数据和整合所搜集资料,查明了环渤海低平原区的0～40cm土壤含盐量现状,在此基础上,以不同盐分情况下的土壤安全容盐值、土壤化学类型和作物布局结构为参考指标,对研究区的土壤安全容盐潜力进行了评价。总的来看,环渤海低平原区的土壤安全临界容盐潜力变化区间为1.0～3.0g/kg,其中以2.0～2.5g/kg的潜力区为主,占总面积的81.3%,整体容盐潜力较大;其他等级1.5～2.0、2.5～3.0和1.0～1.5g/kg的潜力区,分别占10.0%、5.4%和3.1%。土壤安全最大容盐潜力区的变化区间为1.5～5.5g/kg,其中以2.5～3.5g/kg的潜力区为主,占总面积的68.7%,整体容盐潜力较小;其他等级3.5～4.5、1.5～2.5和4.5～5.5g/kg的潜力区,分别占25.2%、5.1%和1.0%。土壤安全临界容盐潜力区和最大容盐潜力区在空间格局上有很好的对应关系,临界容盐潜力大的地区,最大容盐潜力也大;反之,依然。     

水稻群体物质生产过程的计算机模拟

在作物生长过程的电子计算机模拟方面作了一次尝试。建立了计算机模拟所必需的基础软件:将水稻干物质的累积与产量形成分解为几个过程,如 CO₂同化,干物质分配,叶面积扩展,分蘖消长和幼穗分化等,分别制定了数学模型和子程序,并在此基础上建立了水稻群体干物质生产和产量形成的总模型和总程序:进行了水稻群体实验,以确定模型的部分参数。模型的表现在形式上符合实际情况,这说明模型的依据和结构是合理的,但在绝对数量上尚有误差。灵敏度试验提供了关于改变某一参数所产生的影响的信息,这对于指导生产和设计实验有一定的意义。     

内充种垂直轮式新型小麦精量排种器的研究

文章揭示了该新型小麦精量排种器及其核心——排种元件的结构特点，分析论述了该排种器精播小麦的基本原理和参数。排种元件以容腔容积排种，没有带动层，排种定量、准确、可控。     

畜牧业产业化与养殖生物技术工程化

我国进入市场经济体制之后，必然促进畜牧业产业化的快速发展。畜牧业产业化要求技术含量高，需要高新技术的投入，而畜牧业的高科技投入，实质上是现代工程技术的投入。因此，畜牧业产业化先要解决生物技术的工程化，即以先进的工程技术装备养殖业并实现养殖业产品的商品化。养殖生物技术的工程化，必须做好生产工艺、材质材料和工程技术配套的工作。     

Soil microbial communities and enzyme activities in a reclaimed coastal soil chronosequence under rice–barley cropping

Purpose

A field experiment with a reclamation chronosequence under rice?Cbarley cropping was conducted to investigate soil enzyme activities and microbiology in a coastal saline soil. The aim of this study was to test whether changes in enzyme activity and microbial community structure are directly impacted by changes in soil pH, electrical conductivity (EC), and organic carbon (SOC) due to reclamation.

Materials and methods

The research area is located in south-eastern China. Four experimental sites were reclaimed in 1976, 1984, 1996, and 2006, respectively, and each site was divided into three plots, each of which was 22?m?×?10?m. Each year, the plots were planted with rice (cv Xiushui) in summer and barley (cv Yanmai) in winter. Soil pH and EC were determined in an aqueous suspension with a 1:5 ratio of soil and water. Soil organic carbon content was measured by dichromate oxidation with heating. Measured soil enzyme activities included catalase, urease, and protease. Soil microbial community structures were assessed using denaturing gradient gel electrophoresis.

Results and discussion

Reclamation under rice?Cbarley cropping reduced EC and pH, but increased SOC, the activities of catalase, urease and protease, and the cell numbers of bacteria, actinomycetes, and fungi, resulting in an increase in the bacterial community diversity. The enzyme activities and bacterial community diversity were significantly positively correlated with SOC, and negatively correlated with pH and EC. Five bacterial groups related to Gaetbulibacter, Sporosarcina, Flavobacterium, Aequorivita, and Gillisia, which have been associated with saline waters, did not appear in the soils that had been reclaimed prior to 1996.

Conclusions

Results of this field study suggest that soil properties which affect microbial activity such as EC, pH, and SOC significantly influence the activities of catalase, urease, and protease, and microbial community composition. More than 10?years after reclamation under rice?Cbarley cropping, EC had decreased and bacteria typically found in marine and saline environments had disappeared from the soil.     

Isotopic evaluation of the role of arbuscular mycorrhizae in the nitrogen preference in Chinese fir seedlings

Chinese fir seedlings grow well in shrubland (including deciduous forest) soils without or less fertilizer application, but they sometimes harbor disease and show symptoms of nitrogen deficiency in ploughed (including several rotation of Chinese fir plantation) soils, where agricultural practice and clear-felling reduce the abundance and diversity of mycorrhizal fungi, and lead to destruction of mycorrhizae. Based on measurements of foliar δ¹⁵N or foliar δ¹⁵N_fol-soil in seedlings collected from 33 nurseries, we compared the effect of an AM-mediated process on nitrogen resource use between shrubland and ploughed soils. In mycorrhizal seedlings growing in shrubland soils, both foliar δ¹⁵N and foliar δ¹⁵N (fol-soil) were significantly higher than those in ploughed soils, likely because of enhanced high δ¹⁵N/NO₃^? absorption through AM-mediated pathways. Those results showed that foliar δ¹⁵N typically reflected the isotopic signature of the source pools of N. We suggest that the dominant N form taken up by fir seedlings growing in ploughed soils was NH₄⁺-N rather than NO₃^?-N, where colonized root epidermis play an important role in exploiting soil N resource. However, the N form taken up by fir seedling growing in shrubland soils was primarily NO₃^?-N compared to NH₄⁺-N, which is attributed to the high efficiency in an AM-mediated process rather than the dominance of N species in the different habitats. It is conceivable that combined colonized root epidermis with AM-mediated process may be more important than root epidermis alone in exploiting different forms of N in nursery soils. Therefore, in low N and acidic ecosystems, species other than the dominant N-NH₄⁺, should be considered to satisfy the N demand for Chinese fir survival and growth, while the efficiency of an AM-mediated process should be determined by soil abiotic conditions.     

旱地玉米水分高效利用平衡施肥技术的试验研究

通过６年田间试验研究,探讨平衡施肥技术对旱地玉米水分利用的影响。结果表明,在晋东豫西半湿润偏旱区,采用适宜的肥料品种、适宜的肥料用量、适宜的施肥时期以及适宜的施肥培肥方式方法,即采用平衡施肥技术有利于旱地玉米水分利用效率的提高,同时,可培肥土壤、保蓄土壤水分,促进旱地玉米对水分的充分利用     

利用显著图构建注意力深度网络检测诱虫板蔬菜害虫

为提高诱虫板图像蔬菜害虫检测精度,针对背景区域容易导致误检的问题基于显著图分析技术构建了一种注意力深度网络害虫智能视觉检测方法。首先通过显著图筛选出粗候选区域;然后在粗候选区域内用全卷积神经网络精选出细候选区域;接着用神经网络分类器识别细候选区域害虫种类,得到含有冗余的若干检测框;最后用改进的非极大值抑制消除冗余检测框,实现诱虫板图像中目标害虫的检测。针对小菜蛾和瓜实蝇展开试验,获得86.40%的平均精度均值和0.111只的平均绝对计数误差均值,所提方法平均精度均值比Faster R-CNN和YOLOv4分别高2.74和1.56个百分点,平均绝对计数误差均值比Faster R-CNN和YOLOv4分别低0.006和0.003只;同时,消融试验中移除显著图注意力模块后平均精度均值下降了4个百分点、平均绝对计数误差均值增加了0.207只。试验结果表明,所提方法有效提高了诱虫板图像蔬菜害虫检测精度,其中,引入显著图注意力模块对提升检测精度有重要作用。