稻曲病菌致病机制研究进展

 稻曲病是一种水稻穗部病害,在世界各水稻主产区均有发生,已成为世界性病害,在我国也属于水稻主要病害之一。稻曲病的发生严重影响水稻产量和稻米品质。研究其病原菌致病机制,对找寻防治药物的特异性靶标具有重要作用,可为抗病分子育种提供新的思路,为稻曲病菌防治药剂研发提供新的靶标。本文综述了稻曲病菌侵染过程、致病相关基因功能研究、水稻响应稻曲病菌侵染等方面的研究进展,提出进一步研究的策略。现有研究表明,稻曲病菌能成功侵染水稻孕穗期雄蕊的花丝引起发病。病原菌可通过抑制多个水稻免疫途径实现成功侵染;还可模仿胚珠受精激活水稻灌浆、糖代谢等途径为稻曲球的形成提供营养物质;全基因组测序完成和基因编辑技术在基因敲除中的成功应用,为稻曲病菌功能基因研究提供了很好的基础。稻曲病菌独特的侵染过程和营养利用机制是未来研究的重要方向。     

革命根据地农业生产互助组织考察

以大量原始史料为基础,对中国共产党在特定形势下发起的农业生产互助运动进行了研究,考察了这一时期革命根据地农业生产互助组织的组织特征、运行机制和绩效。     

黑大蜜蜂的研究进展

黑大蜜蜂Apis laboriosa是蜜蜂属个体最大的蜜蜂,与大蜜蜂有很多相似之处。目前,我国黑大蜜蜂仍处于半野生状态的原始方式饲养。概述黑大蜜蜂的分类地位、生物学、天敌及防御机制、经济价值等,提出保护黑大蜜蜂的重要意义及建议,旨在利用黑大蜜蜂为农业发展带来最大效益。     

Chemical changes of kenaf core binderless boards during hot pressing (I): influence of the pressing temperature condition

Self-bonding is the main factor of the performance expression of binderless boards, and therefore its clarification is considered to be an important issue. For this purpose, a series of chemical analyses were conducted on kenaf core binderless boards and their chemical changes during the hot-pressing process are discussed in this article. First of all, binderless boards were prepared from kenaf core powder at different pressing temperatures (without steam-explosion process) and were used for chemical analyses after they were reduced into powders and extracted with methanol. To investigate their chemical changes, lignin, holocellulose, and neutral sugar contents were determined, Fourier transform infrared (FTIR) spectra were recorded, and the nitrobenzene oxidation procedure was applied. As a result, it was found that parts of lignin and hemicelullose were decomposed during the hot-pressing process; however, the contribution of the resulting fractions to selfbonding was not observed. In addition, progress of condensation reactions in lignin and the formation of chemical bonds by low molecular weight conjugated carbonyl compounds in methanol extractives were observed. Thermal softening of lignin is also suggested to play an important role in the expression of board performance.     

我国家庭农场的生成机制、发展现状与现实约束

基于相关历史与现实背景,从经济性激励与社会环境改善两大视角研究家庭农场的生成机制,对家庭农场经营规模、发展速度、经营收益、经营方式、宜机化程度等现状进行探讨,得出经营者文化程度低、融资难、品牌与合作意识不强、现代信息技术应用不足等结论,并从人才培养、政策扶持、规范管理、配套服务等方面为家庭农场未来发展提供建议,以期助力乡村振兴。     

细胞钙超载与鸡柔嫩艾美耳球虫病损伤关系

为探讨鸡柔嫩艾美耳球虫（E．tenella）宿主细胞损伤与钙超载的关系，采用组织定量检测、Von Kossa钙染色、焦锑酸钾电镜细胞化学技术对使用和未使用钙离子阻断剂的E．tenella感染鸡盲肠组织的细胞沉积钙、ATP酶、磷脂酶A2（PLA2）、游离脂肪酸和盲肠上皮细胞游离Ca^2＋的含量与分布进行了动态测定和分析。结果表明：（1）鸡患柔嫩艾美耳球虫病过程中，宿主细胞内钙和游离Ca^2＋明显增多（P〈0．01），并随盲肠损伤加重而增加；（2）在发病过程中盲肠组织Na^＋-K^＋-ATP酶、Ca^2＋-Mg^2＋-ATP酶、总ATP酶活性均有不同程度的下降，在感染严重期显著低于不感染对照组（P〈0．01）；（3）钙超载盲肠组织的PLA2活性和游离脂肪酸含量明显升高（P〈0．01），表明钙超载是鸡柔嫩艾美耳球虫病的一个重要损伤机制；（4）硝苯地平可以阻止Ca^2＋内流，减少宿主细胞内游离Ca^2＋，减轻宿主细胞的损伤，在本病发生的早期盲肠损伤较轻时，对鸡有一定的保护力，但随着疾病的发展，其作用下降。     

Predictive modes of action of pesticides in uterine adenocarcinoma development in rats

Endometrial adenocarcinoma in the uterine corpus is a malignant cancer that occurs in menopausal women and aged rodents. Because of the similarities in pathogenesis and morphology of endometrial adenocarcinoma in rodents and humans, prediction of the modes of action (MOA) in uterine carcinogenesis is important for extrapolation of rodent data to humans. Three MOAs have been accepted as major pathways for uterine carcinogenesis in rodents: 1) estrogenic activity, 2) increased serum 17beta-estradiiol (E2) to progesterone (P4) ratio and 3) modulation of estrogen metabolism to produce 4-hydroxyestradiol via P450 induction. Inhibition of estrogen excretion and increased aromatase in situ in the tumor are also a potential pathway. Here, chemicals showing uterine carcinogenicity were chosen from approximately 300 pesticides evaluated in Japan within the past decade, and their mechanisms were predicted using parameters from mechanistic and toxicity studies. Seven pesticides increased uterine tumor formation in rats, and the pathways of 4 pesticides could be predicted based on various mechanistic studies. The MOAs of cyenopyrafen and benthiavalicarb-isopropyl were predicted to be modulation of estrogen metabolism, while those of pyriminobac-methyl and spirodiclofen were predicted to be increased E2 to P4 ratio. The driven pathways of metazosulfuron and isopyrazam could not be predicted using several mechanistic studies. No mechanistic studies have been reported for sedaxane, which has a chemical structure and toxicological profile similar to isopyrazam. Our results indicated that appropriate mechanistic studies are useful for mechanism prediction in risk assessment. From this analysis, a flowchart showing a decision tree for predictive MOAs in uterine carcinogenesis was proposed.     

奶业产业链纵向价格传导的时滞效应与政策启示

奶业产业链纵向价格传导受阻,导致奶牛养殖长期处于价值链的低增值环节,甚至出现“行业萎缩”现象.本文对上游奶牛养殖成本向下游乳品加工环节价格传导机制进行理论分析,并基于2008年1-12月份奶牛饲养成本和原料奶价格的月度数据,运用有限分布滞后模型测度价格传导的滞后效应.结果 表明:饲养成本向下游传导存在显著的滞后性,饲养...     

Age estimation of different tree species using a special kind of an electrically recording resistance drill

The determination of tree age is an important issue for urban green planning, forestry and dendrology; finding non-destructive and quasi-non-destructive methods for this purpose is of great theoretical and practical importance. The resistance drilling method is quasi-non-destructive because the average diameter of an opening that remains after drilling does not exceed 3 mm. Do electrically recording resistance drills allow precise assessment of tree age? The aim of this study is to assess the accuracy of determining the number of tree rings based on an examination of this special kind of drilling resistance profiles for three tree species, the pine Pinus sylvestris L., the oak Quercus robur L., and the birch Betula pendula ROTH. In 2015 and 2016, 15 pine trees, 15 oak trees, and 15 birch trees were randomly selected. For each studied tree, a measurement was conducted using the electrically recording resistance drill IML-Resi E400 with a flat-tipped 1.5/3 mm steel needle (research sample), and an increment core was taken (reference sample). The drill used was not a real Resistograph^®. The analysis of the E400-profiles underestimated the number of tree rings; the mean bias error (MBE) values were –6.5, –2.5, and –6.0 years for pine, oak, and birch, respectively. The proportion of investigated trees with less than five years difference between the research and reference samples varied from 38.4 (birch) to 66.7 (oak) percent. The accuracy of tree age determination was lowest for birch and highest for oak. The binomial generalised linear model (GLM) revealed that the most accurate tree age assessments were obtained from tree rings wider than 2 mm. The measurements clearly showed that the electrically recording resistance drill IML-Resi E400 enables a quick, although approximate, tree age assessment. Future research should concentrate on electronically regulating and recording drills, providing a higher spatial and signal resolution, and a stronger correlation to wood density.