甘蔗根癌农杆菌介导转化海藻糖合酶基因获得抗渗透胁迫能力增强植株

 由双拷贝CaMV35S启动子驱动担子菌灰树花 (Grifolafrondosa)的海藻糖合酶基因 (TSase)构建植物表达载体 pBBBT ,通过三亲交配法将 pBBBT导入根癌农杆菌EHA10 5菌株 ,经根癌农杆菌介导转化甘蔗 (Saccha rumhybrid)栽培品种 ,以增强甘蔗的抗旱能力。结果表明 ,甘蔗胚性愈伤组织对EHA10 5菌株敏感 ,甘蔗外植体开始大量形成胚性愈伤组织时是感染的适宜时期 ,用膦丝菌素 (PPT)筛选 ,抗性植株发生频率平均为 4 .5 %。经PCR及dot Southern检测证明 ,TSase已经整合到甘蔗基因组中。部分转化植株根叶畸形、株型异常、生长缓慢。移栽到含PEG80 0 0 17.4 % (w/v)的MS培养基后 ,观察到转基因植株抗渗透胁迫能力增强     

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.     

Seasonal speedup along the western flank of the Greenland Ice Sheet

It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%). Furthermore, the dominant seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow.     

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。     

Long-term trends in the abundance of Mediterranean wetland vertebrates: From global recovery to localized declines

Biodiversity loss is unevenly distributed in space and time. Species have reached critically low population sizes in some areas, and remain abundant in others. Similarly, some species may benefit from successful conservation plans, while others still experience severe population depletions driven by negative impacts of human activities. Although several indicators have been proposed to measure the fate of biodiversity, they are generally only implemented globally so their relevance for regional assessment is still unclear. Here, we calculated the first regional trend in the Living Planet Index for the Mediterranean wetlands (Med LPI), an indicator that summarizes the fate of global biological diversity based on the temporal trends in abundance of vertebrate populations. The Med LPI was based on 1641 vertebrate populations of 311 species recorded in Mediterranean wetlands from 1970–2008, in 27 different countries. We investigated whether trends in the Med LPI differed between eastern and western Mediterranean countries, which have different socio-economic contexts. Finally, we assessed whether and how the trend in the Med LPI was robust to changes in the number and identity of species considered. We found that, at the Mediterranean scale, the Med LPI increased steeply, which could be taken at first sight, as a general recovery of wetland biodiversity in this biogeographical region. However, we found highly contrasting spatial trends within the Mediterranean region: the average trend was positive for western and negative for eastern countries. Moreover, we showed that depending on the method used to estimate the trend in Med LPI, it can be sensitive to the number and identity of the species considered. We suggest that understanding the regional discrepancies of the trend in biodiversity indicators as well as their robustness to the species represented in the index will enhance progress assessment towards global and regional conservation strategies.