本科酶工程课程教学实践与体会

酶工程是高校生物工程和生物技术专业重要的专业课。结合课程教学实践,总结了酶工程教学过程中的几点体会,以提高酶工程教学质量,达到学生综合能力的培养目的。     

试论微型学习之于传统学习的优势

微型学习是以微型内容为特点,微型媒体为支撑的非正式学习模式。它适应了当代生活语境下人们对知识获取方式创新的要求,倡导了学习者尊重自身生命体验的情感回归,体现了人作为受教育者的社会性发展的重要路径,同时也为培养学习者综合能力提供了重要平台。     

Contribution of incident solar radiation on leaves and pods to soybean seed weight and composition

The weight and composition of soybean seeds (Glycine Max L. Merrill) depend on changes in carbon and nitrogen assimilate supply during grain filling. Soybean pods and seeds are green, evidencing their capacity to capture light. However, the current physiological knowledge does not consider any effect of incident solar radiation reaching the pods on seed weight and composition. The objective of this work was to investigate the response of seed weight and composition to changes in assimilate supply from leaves, to the incident solar radiation reaching the pods and to the combination of both, changes in assimilate supply from the leaves and incident solar radiation on pods of soybean plants. Field experiments were performed during two growing seasons at Balcarce, Argentina. Treatments modified the amount of assimilates supplied by the leaves (plant shading, defoliation), the solar radiation reaching the pods (pod shading) or both (defoliation and pod shading) during seed filling. Plant shading and defoliation reduced seed weight, oil concentration and oil and protein content and increased the concentration of saturated and poli-unsaturated fatty acids while reduced oleic acid percentage. Pod shading increased the concentration of stearic acid and reduced the concentration of linolenic acid. When pods were shaded on defoliated plants, seed weight and oil and protein content decreased while fatty acid composition was similar to values obtained under defoliation treatment. Based on these results, a conceptual model that considers photoheterotrophic nature of reproductive structures of soybean is proposed. Seed weight, oil and protein content and oil fatty acid composition depended on assimilate availability for the seeds. The response of oil and protein content to assimilate supply depended on whether leaves were present or not. The effect of solar radiation incident on pods depended on the amount of assimilates available for the seeds: (i) when carbon allocated was low (defoliation treatments), pods contributed to seed carbon economy but solar radiation incident on them did not affect fatty acid composition; (ii) when carbon allocated to the seeds was high (intact plants), contribution of pods to seed carbon economy was not significant, but the amount of solar radiation incident on pods produced significant changes in fatty acid composition.     

Estimation of litchi (Litchi chinensis Sonn.) leaf nitrogen content at different growth stages using canopy reflectance spectra

The estimation of crop nitrogen status in fresh vegetation leaf using field spectroscopy is challenging due to the weak responses on leaf/canopy reflectance and the overlapping with the absorption features of other compounds. Although the spectral indices were proposed in the literature to predict leaf nitrogen content (LNC), the performance of selected spectral indices to estimate the LNC is often inconsistent. Moreover, the models for nitrogen content estimation changed with the growth stage. The goal of this study was to evaluate the performance of published indices, ratio of data difference index (RDDI) and ratio of data index (RDI) developed by band iterative-optimization algorithm in LNC estimation. The correlation analysis, linear regression and cross validation were used to analyze the relationship between spectral data and LNC and construct the best performed estimation model. The study was conducted by the data of five growing seasons of litchi from the orchards in Guangdong Province of China. Results showed that the relationship between chlorophyll (Chl) related spectral indices and LNC varied with the growth stage. Even in flower bud morphological differentiation stage and autumn shoot maturation stage, there were not significant correlations between the proposed spectral indices and LNC. Besides it is difficult to estimate the LNC by the general model across the growth stages due to the integrated effects of cultivar, biochemical, canopy structure, etc. The band iterative-optimization algorithm can improve the sensitivity of spectral data to LNC to some extent. The optimal RDDI performed better than other indices for the synthetic dataset and the dataset in each growth stage. And the sensitive bands selected in the optimal indices at each growth stage are not consistent, which are not only related to the Chl absorption but also other biochemical components, such as starch, lignin, cellulose, protein, etc. In general, the LNC can be estimated by the optimized CR-based RDDI indices in autumn shoot maturation stage, flower spike stage, fruit maturation stage, and flowering stage with the R² > 0.50 and RMSE < 0.14. Although there were the significant relationship between RDIs and RDDIs in flower bud morphological differentiation stage, the highest R²s of the model developed by RDDIs and RDIs were less than 0.50 in cross validation. This study indicated that the applicability of canopy reflectance to estimate litchi LNC was closely related to the growth stage of litchi. Growth stage-specific models will be preferred for estimating litchi LNC estimation.     

超干种子老化方法比较研究

本试验种用谷子、绿豆，经４０℃及４５℃，湿度ＲＨ＝９５％－１００％老化６天及５天。然后测各含水量的５项活力指标。经生物统计表明：谷子４０℃，４５℃二处理间差异显著，且４０℃高温老化６天时间，在不同含水量的组合上，除含水量０．８５％外，其余二因子组合均优于４５℃老化６天的不同含水量处理，且有０．０１显著差异。绿豆老化温度亦以４０℃较好，种子含水量老化结合谷子和绿豆均以５．８％处理效果最好，二种作物经     

构树的营养价值及其在畜禽生产中的应用研究进展

构树含有丰富的粗蛋白、粗脂肪、氨基酸等多种营养物质,有抗氧化、抗菌消炎的功能。构树在畜禽养殖中的应用有助于解决我国的"人畜争粮"问题,有望成为一种具有广泛应用前景的蛋白质饲料。文章综述构树的营养成分、生物发酵技术以及在猪、家禽、反刍动物养殖中的应用研究进展。     

超高效液相色谱法测定饲料中斑蝥黄和β-阿朴-8’-胡萝卜素酸乙酯含量方法的研究

为有效快速测定饲料中斑蝥黄和β-阿朴-8’-胡萝卜素酸乙酯含量,饲料经甲醇、正己烷和乙酸乙酯混合液萃取后,在氮气保护下浓缩,用甲基叔丁基醚-乙腈溶液复溶,注入超高效液相色谱仪中进行测定。结果表明:斑蝥黄浓度为1.25~10.0μg/mL,β-阿朴-8’-胡萝卜素酸乙酯为2.50~20.0μg/mL线性关系良好;斑蝥黄和β-阿朴-8’-胡萝卜素酸乙酯的检测限为0.06 mg/kg,定量限为0.20 mg/kg。斑蝥黄5个添加水平的平均回收率为72.8%~82.8%,相对标准偏差(RSD)为0.41%~1.06%;β-阿朴-8’-胡萝卜素酸乙酯5个添加水平的平均回收率为72.0%~82.8%,RSD为0.46%~1.41%。说明该方法简便、快速、灵敏度高、准确度好,适用于测定饲料中斑蝥黄和β-阿朴-8’-胡萝卜素酸乙酯含量。     

柠条枝条覆盖对宁夏荒漠草原土壤水热及补播牧草生物量的影响

干旱是影响宁夏东部沙化区荒漠草地退化的主要自然因素,也是天然草地补播成功率低的主要原因,该地区大面积种植的柠条是土壤覆盖保水的丰富资源,但是缺乏相关研究。选择平坦的、未生长柠条的退化天然补播草地作为研究对象,在临近有柠条生长的草地平茬其柠条枝条用于试验覆盖,研究不同柠条覆盖厚度（TSM₀,覆盖0 cm;TSM₁,覆盖1 cm;TSM₂,覆盖2 cm;TSM₃,覆盖3 cm）对该地区荒漠草地0~40 cm土壤水热以及补播牧草地上生物量的影响。结果表明,柠条枝条覆盖显著提高了土壤含水量,并且随着覆盖厚度的增加逐渐增大,但2018和2019年间所有覆盖处理下0~20 cm土壤水分平均值与TSM₀之间差异不显著（P>0.05）;在20~40 cm土层,3种柠条枝条覆盖厚度明显较对照提高了土壤水分含量,表现出TSM₃>TSM₂>TSM₁>TSM₀的趋势。结果还表明,柠条枝条覆盖还具有降低草地0~10 cm温度的作用,生长季8：00、14：00和18：00的土壤温度总体均随着柠条枝条覆盖厚度的增加出现降低趋势,且2019年土壤温度随着覆盖厚度的增加,变异系数也在减小,依次为4.6%、2.3%、1.7%,表明覆盖对土壤温度的变化具有缓冲作用。补播牧草地上生物量亦随着覆盖厚度的增加而增大,蒙古冰草、沙打旺及补播的3种牧草的总生物量均与草地20~40 cm土壤水分呈显著正相关（P<0.05）。本研究表明,柠条枝条覆盖有效地改善了荒漠草地土壤的水热,提高了土壤墒情,为牧草种植提供了良好的生长环境,可为该地区及类似地区退化草地的补播改良提供技术借鉴。     

放牧对草甸草原土壤水热状况和地上生物量的影响

本文以呼伦贝尔草甸草原为对象,研究了不同放牧强度对草原群落土壤水热状况和地上生物量的影响,旨在揭示二者之间的相互关系。研究结果表明,随着放牧强度的增加,生长季平均土壤温度呈逐渐上升的趋势;放牧对群落3个组份[羊草（Leymus chinensis）、贝加尔针茅（Stipa baicalensis）、杂类草]生物量和相对优势度产生影响。其中,羊草地上生物量和优势度随着放牧强度的增加显著线性降低,而贝加尔针茅和杂类草的生物量与优势度均在中度放牧处理下最高。土壤含水量与羊草生物量显著正相关,与杂类草生物量负相关,而与贝加尔针茅生物量间的关系极弱。本研究为完善放牧优化理论,揭示放牧在草地生态系统功能过程中的梯度效应提供了一个较为重要的研究线索,为草地放牧优化管理制度的确立提供了一定的科学依据。     

稻谷籽粒的压缩特性与含水率关系的实验研究

通过Brookfield质构仪测定了不同含水率的稻谷籽粒(含水率为10.63%、12.25%、13.71%、15.18%、16.53%w.b.)在Z轴(短轴)方向上的压缩特性(破坏力、破坏能、表观接触弹性模量、最大接触应力、破坏应变),得出含水率对稻谷压缩特性的影响规律。实验结果表明:随着压缩形变的增加,稻谷籽粒受到的压力逐渐增加,当到达破裂点时达到最大值,随之急剧减小。随着含水率的增加,稻谷籽粒的压缩破坏力、破坏能、表观接触弹性模量、破坏应力逐渐减小,压缩破坏应变逐渐增加。