抓低改促高产求发展——双峰乡实施毛竹丰产经营的调查

双峰乡是中国“毛竹之乡”——宜丰县的毛竹重点产区.在对毛竹林的经营中,双峰乡通过全面规划、分类改造,改革机制、多种管理方式经营,建设样板、典型带动推广,以及基地建设与竹材深加工开发相结合等一系列措施,使这个“双料”的毛竹之乡真正发挥了资源优势,实现了毛竹丰产高效,促进了地方经济发展.调查总结了其成功的竹林经营管理经验,还介绍了向全县推广的措施方法.     

Magnetic microstructure of magnetotactic bacteria by electron holography

Off-axis electron holography in the transmission electron microscope was used to correlate the physical and magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria. The magnetite crystals were all single magnetic domains, and the magnetization directions of small superparamagnetic crystals were constrained by magnetic interactions with larger crystals in the chains. Shape anisotropy was found to dominate magnetocrystalline anisotropy in elongated crystals. A coercive field between 300 and 450 oersted was determined for one chain.     

Effect of breed of cattle on transmission rate and innate resistance to infection with Babesia bovis and B bigemina transmitted by Boophilus microplus

OBJECTIVE: To assess the effect of breed of cattle on the transmission rates of and innate resistance to Babesia bovis and B bigemina parasites transmitted by Boophilus microplus ticks. DESIGN: Groups of 56 purebred B indicus and 52 B indicus cross B taurus (50%, F1 generation) steers were placed in a paddock seeded with and also naturally infested with B microplus which were the progeny of females ticks fed on B taurus cattle specifically infected with a virulent isolate of B bovis. The cattle were placed in the infested paddock 50 days after seeding had started. PROCEDURE: Cattle were inspected from horseback daily for 50 days. Clinically ill cattle were brought to yards and assessed by monitoring fever, depression of packed-cell volume, parasitaemia and severity of clinical signs. Any animals that met preset criteria were treated for babesiosis. Blood samples were collected from all cattle on day 28, 35 and 42 after exposure and antibodies to Babesia spp and packed cell volume measured. RESULTS: All steers, except for one crossbred, seroconverted to B bovis and B bigemina by day 35 and 75% of the crossbred steers showed a maximum depression in packed cell volume of more than 15% due to infection with Babesia spp compared with only 36% of the B indicus group. Ten of the 52 crossbreds and 1 of the 56 B indicus steers showed severe clinical signs. Two of the crossbreds required treatment of which one died 2 weeks after initial treatment. CONCLUSIONS: Pure-bred B indicus cattle have a high degree of resistance to babesiosis, but crossbred cattle are sufficiently susceptible to warrant the use of preventive measures such as vaccination. Transmission rates of B bovis and B bigemina to B indicus and crossbred cattle previously unexposed to B microplus were the same.     

水分胁迫下4种冷季型草坪草抗旱性比较研究

采用盆栽育苗法,研究了4种冷季型草坪草在不同水分胁迫下的抗旱性,结果表明:1)随着水分胁迫程度的加深,4种冷季型草坪草的外观质量和叶片相对含水量显著下降,细胞质膜透性、MDA含量和Pro含量上升。2)模糊数学综合评价结果表明,4种冷季型草坪草种抗旱性能由强到弱的顺序为:高羊茅>多年生黑麦草>草地早熟禾>匍匐翦股颖。     

Magnetic Collapse in Transition Metal Oxides at High Pressure: Implications for the Earth

Magnetic collapse in transition metal ions is predicted from first-principles computations at pressures reached in the Earth's lower mantle and core. Magnetic collapse would lead to marked changes in geophysically important properties, such as elasticity and conductivity, and also to different geochemical behavior, such as element partitioning, than estimated by extrapolating low-pressure data, and thus change the understanding of Earth's structure and evolution. Magnetic collapse results from band widening rather than from changes in crystal field splitting under pressure. Seismic anomalies in the outer core and the lowermost mantle may be due to magnetic collapse of ferrous iron, dissolved in iron liquid in the outer core, and in solution in magnesiowustite in the lowermost mantle.     

克拉玛依果树腐烂病病原菌鉴定及其拮抗菌的筛选

【目的】提高克拉玛依果树腐烂病生物防治的效率,为相关果树高效生物防治提供科学依据和物质基础。【方法】从克拉玛依林杨的苹果树和李子树腐烂病发病植株及周边采集病灶和土壤样品,分析病原菌及其拮抗菌的筛选及微生物分子鉴定及拮抗效果。【结果】苹果树和李子树腐烂病病原菌均黑腐皮壳菌属（Valsa）,其中李子树病原菌涉及该属的两个种：Valsa mali 和Valsa leucostoma ,而苹果树病原菌仅为Valsa mali。同时获得各类真菌拮抗菌15株,涉及4个属9个种,筛选到具有高效拮抗细菌2株,其最大抑菌圈菌落比分别达到2-11和2-79。【结论】菌株芽孢杆菌B4和B6对果树腐烂病具有较好的抑菌效果,研究报道了李子树腐烂病病原菌,为相关果树的高效生物防治提供了科学依据和物质基础。     

OsPPR9 encodes a DYW-type PPR protein that affects editing efficiency of multiple RNA editing sites and is essential for chloroplast development

Photosynthesis occurs mainly in chloroplasts, whose development is regulated by proteins encoded by nuclear genes.Among them, pentapeptide repeat(PPR) proteins participate in organelle RNA editing. Although there are more than 450members of the PPR protein family in rice, only a few affect RNA editing in rice chloroplasts. Gene editing technology has created new rice germplasm and mutants, which could be used for rice breeding and gene function study. This study evaluated the functions of OsPPR9...