Testosterone improves the transition of primary oocytes in artificial maturation eels (Anguilla japonica) by altering ovarian PTEN expression

In mammals, androgens appear to enhance the development of primary ovarian follicles, but PI3K (phosphoinositide 3-kinases) pathway is well recognized as one of the critical pathways in early follicular development. Roles of the PI3K were revealed by deletion of PTEN (phosphatase and tensin homolog on chromosome 10). PTEN is demonstrated to play an important role in the early stage of follicle development. In the Japanese eel, two forms of PTEN have been cloned, but what their functions on the development of early ovarian follicles are still not clear. The natural blockage and inducible of ovarian development was a benefit to address this question in the eel. Testosterone (T) shows to ameliorate the early ovarian development in the eel. The aims of this study were to elucidate the two forms of PTEN by cellular and physiological criteria and to study the effects of T on the ovarian PTEN production in the exogenous pituitary extracts-stimulated eel. Our results suggested that two forms of PTEN are existing in the Japanese eel, and eel ovarian development corresponded to the decrease in ovarian PTEN expression, vice versa. In addition, the supplement of T on eel early ovarian development can be attributed to its PTEN inhibitor role.     

气力式油菜、小麦兼用精量排种器设计及排种分析

为提高播种机具的利用率,实现油菜和小麦的兼用播种,本文针对油菜和小麦的机械物理特性,设计了一种气力式油菜小麦兼用型精量排种器,确定了排种滚轮、护种板、气室等关键部件的主要结构参数;分析了充种、清种和卸种过程中的种子运移规律,得出油菜、小麦的充种极限速度分别为0.18m/s、0.13 m/s,油菜、小麦的护种板护种角分别为31.5?~43.2?、36.18?~41.40?, 油菜、小麦的气室气压分别为＞342Pa、＞458Pa。台架试验表明所设计的排种器能满足农艺上油菜和小麦播种的要求。      

深圳国际园林花卉博览园园容管理经验探讨

深圳国际园林花卉博览园是一个集团林花卉博览、文化艺术、科普教育、旅游展览于一体的综合公园.2004年9月23日正式开放.2008年9月12日,被住房和城乡建设部评为"国家重点公园".园博园是第五届中国国际园林花卉博览会举办地.该届园博会开创建设市政公园与举办园博会合二为一的模式,取得了良好的社会、经济和环境效益,结合这些特点,总结了园容管理,提出了发展思路.     

双黄连制剂药理作用及其在兽医临床中的应用分析

双黄连制剂是纯中药制剂,通过金银花、连翘、黄芩3味中药精制而成,其临床疗效主要为清热解毒、辛凉解表。目前,临床上应用的双黄连制剂主要有可溶性粉、口服液和注射液。进一步的研究双黄连制剂的药理作用,为实际兽医临床应用提供理论依据和起到参考作用。     

韩庚辰13载无怨无悔创业路

眼前走过来的这个人,皮肤略黑、穿着朴素。“你好,我是韩庚辰!”从他的口音可以听出来,他是河南人。     

全球大米供求和贸易形势分析与预测

分析了1960年以来全球大米供求、贸易和价格变动趋势,并利用WATERSIM模型对未来全球大米供求、贸易和价格变化进行了预测。从中长期看,全球大米贸易量还会有较大增长,亚洲和非洲部分经济不发达地区大米供求不平衡更为明显,但未来世界大米价格将会从近年来的高位逐步下降到一个合理的水平。历史上美元贬值是世界大米价格暴涨最主要的原因,因此美国应在稳定国际大米等粮食市场中承担更多的责任。     

全球对虾贸易与出口竞争力分析

对虾是全球流通性最大的渔业产品,出口量占全球生产总量的1/3以上.全球对虾贸易主要集中在亚洲、美洲和欧洲这三大区域,泰国、越南、中国等发展中国家是国际对虾市场的主要供给者,美国、日本、欧盟是主要需求者.随着对虾供给的充分和需求市场的饱和,国际对虾市场竞争日益激烈,产品的比较优势是影响对虾出口竞争力的关键因素.     

茄子及其近缘野生种遗传多样性及亲缘关系的AFLP分析

为了明确茄子育种资源的遗传差异和亲缘关系,对来自国内外的54份栽培种茄子高代自交系以及4份近缘野生种进行了遗传多样性的AFLP分析.结果表明:10对EcoRI/MseI引物组合共扩增出570条多态性条带.平均多态率为57%.其中54份栽培种内扩增出120条多态性条带,平均多态率为16%:各引物组合在栽培种内的平均观测等位基冈数、平均有效等位基因数、平均Nei's基因多样度和平均香农信息指数分别为1.176、1.084、0.0051、0.079.基于Jaccard's相似系数采用Complete linkage法进行聚类分析,结果显示:近缘野生种与栽培种的平均遗传距离由近到远依次为红茄、托鲁巴姆、龙葵:栽培种内不同自交系间的相似系数在0.904以上.在相似系数0.915处.栽培种可以分为两个大类;聚类结果与果实性状(果皮色、肉色、果形)和地理来源存在一定的相关性.     

可见光固化天然胶乳压敏胶的研制

采用可见光引发体系固化将降解天然胶乳与萜烯树脂乳液的其他助剂组合制备水乳型压敏胶,研究在一定光照强度下,降解天然胶乳与萜烯树脂乳液的不同配比,天然胶乳不同分子量,其他助剂的用量对压敏胶性能的影响。结果表明,降解天然胶乳与萜烯树脂乳液质量比为1∶1、降解天然胶乳分子量为19.8×10^4、引发剂1.2%、交联剂15%、促进剂0.4%时压敏胶性能最优。DSC和TG/DTG表明含有光引发剂的压敏胶在光照后热稳定性提高,压敏胶的Tg升高了5℃,仍具有很低的使用温度。     

Influences of nitrogen fertilizer application rates on radish yield, nutrition quality, and nitrogen recovery efficiency

Radishes (Raphanus sativus L.) were grown in plastic pots in a screenhouse to investigate the influences of nitrogen fertilizer application rates (NFAR) on yield, nitrate content, nitrate reductase activity (NR), nutrition quality, and nitrogen recovery efficiency (NRE) at commercial mature stage. Five N-rate treatments, 0.644, 0.819, 0.995, 1.170, and 1.346 g·pot⁻¹, were set up in the screenhouse pot experiments, and nitrogen fertilizer (unlabeled N and ¹⁵N-labeled fertilizer) was applied as basal dressing and topdressing, respectively. The results indicated that the fresh and dry weight yields of radish increased with the increase of NFAR at the range of 0.099 to 0.180 g N·kg⁻¹ soil, decreased at 0.207 g N·kg⁻¹ soil, and accordingly there was a significant quadratic relationship between the fresh and dry weight yields of radish and the NFAR. At the high addition of urea-N fertilizer, the nitrate content accumulated in the fleshy roots and leaves due to the decline in NR activity. From 0.644 to 0.819 g N·pot⁻¹ NR increased most rapidly, the highest NR activity occurred at 0.819 g N·pot⁻¹, and the lowest NR activity happened at 1.346 g N·pot⁻¹. Soluble sugar and ascorbic acid initially increased to the highest value and then decreased, and, contrarily, crude fiber rapidly decreased with the increase of NFAR. Total N uptake (TNU), N derived from fertilizer (N_dff), and N derived from soil (N_dfs) in radish increased, except that N_dfs relatively and slightly decreased at the rate of 0.207 g N·kg⁻¹soil. The ratio of Ndff to TNU increased, but the ratio of Ndfs to TNU as well as NRE of N fertilizer decreased with the increase of NFAR. Therefore, the appropriate NFAR should be preferably recommended for improving the yields and nutrition qualities of radish and NRE of N fertilizer. These authors contributed equally to this work