Long-Term Variable Rate Lime and Phosphorus Application for Piedmont No-Till Field Crops

Variable rate (VR) fertilizer application is a paradigm with potential to improve input efficiency and farm profitability. It is widely marketed by commercial applicators in the southeastern US. However, field studies comparing VR with traditional management have not demonstrated consistent, positive results. The objectives of this study were: (1) to determine the soil impact, crop response and economic potential of VR phosphorus (P) and lime application in a North Carolina Piedmont no-till field crop system using intensive soybean [Glycine max (L.) Merr.] production and (2) to economically evaluate alternatives to standard commercial grid soil sampling for directing VR P and lime. A 23-ha long-term no-till field in the SE Piedmont was divided into 0.4ha plots assigned to either VR or uniform P and lime application. Grid soil sampling and VR P and lime application were done prior to four crops over 3 years: full season soybean, wheat (Triticum aestivum L.)–double cropped soybean, and full season soybean. Soil test P, pH and crop yield response to VR P were inconsistent. Soil pH in areas with low pH initially did increase in response to VR lime, but it took two to three applications to bring all of these areas to the target pH. Once VR-liming raised initially low soil pH to levels close to target, yield of soybean, but not wheat, were up to 0.74Mgha^–1 higher than with uniform lime. Even with significantly higher soybean yields associated with VR lime, 3 years of grid sampling and VR application were not profitable compared to uniform application. The results indicated that VR lime could be profitable if the initial grid sampling data were used either for 2 consecutive years, or if it was used to restrict future grid sampling to specific areas requiring further VR lime.     

Biosynthesis of the enediyne antitumor antibiotic C-1027

C-1027 is a potent antitumor agent with a previously undescribed molecular architecture and mode of action. Cloning and characterization of the 85-kilobase C-1027 biosynthesis gene cluster from Streptomyces globisporus revealed (i) an iterative type I polyketide synthase that is distinct from any bacterial polyketide synthases known to date, (ii) a general polyketide pathway for the biosynthesis of both the 9- and 10-membered enediyne antibiotics, and (iii) a convergent biosynthetic strategy for the C-1027 chromophore from four building blocks. Manipulation of genes governing C-1027 biosynthesis allowed us to produce an enediyne compound in a predicted manner.     

云南香料烟害虫种类及发生规律研究

通过6a系统调查,在云南省香料烟主产区烟田内共发现7目31科88种昆虫和野蛞蝓、灰巴蜗牛2种软体动物危害云南冬春香料烟。其中重要害虫是烟蚜（Myzus persicae Suizer）、棉铃虫（Heliothis arrnigera Hubner）、烟草夜蛾（Heliothis assuha Guenee）、烟草盲蝽[Cyrtopeltis tenuis（Reuter）]、野蛞蝓（Agriolimax agresfis Linnaeus）、小地老虎（Agrotis ypsilon Rottemberg）、东方蛄蝼（G．orlentalis Burmeister）、小长蝽（Nysius ericae（Schilling）]等7种。烟蚜、野蛞蝓、小地老虎均为香料烟和烤烟上的重要害虫,在发生危害时期上较一致。棉铃虫、烟草夜蛾在香料烟上危害损失较大．而在烤烟上危害较轻。东方蝼蛄和小长蝽是香料烟上的主要害虫,在烤烟上发生较少,烟草盲蝽和金龟子在香料烟上发生较少．却又是烤烟的主要害虫。     

桑园小长蝽发生危害规律及防治技术研究

 1998年在云南陆良县首次发现小长蝽［(Nysius ercae(schilling)］危害桑树,有的桑园暴发成灾。经1998～2000年调查研究,小长蝽1年发生1代,以成虫在桑园内外杂草丛中越冬,4月下旬至6月中旬是若虫大量发生时期,此时正值桑树发芽抽条,若虫以刺吸式口器吸食桑芽养份和水份,造成桑芽生长不良,不易展叶,以致枯萎脱落。小长蝽发生危害与气候条件、耕作栽培水平有关清洁田园,冬季提早翻耕桑园,翻耕前喷洒化学农药、深施腐施厩肥,桑芽萌发期(4月上旬)喷药防治等综合措施,能有效的控制其危害。     

Lhx2 selector activity specifies cortical identity and suppresses hippocampal organizer fate

The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer.     

关于我国发展适于深加工优质专用玉米的思考

 介绍了我国玉米生产的现状、存在问题以及世界玉米生产和加工情况,提出我国玉米生产发展的方向为稳定普通玉米生产,迅速扩大专用玉米生产,从粉、糖、酒、酸、油5个方面研究、开发相应的加工技术,从而发挥我国玉米资源优势,解决玉米相对过剩的问题,为玉米深加工的长远发展打下基础。