松材线虫Bx-Daf-22基因鉴定及表达

[目的]为探究松材线虫(Bursaphelenchus xylophilus)抗逆态幼虫DL3(Dauer larvae3)形成的分子机理,对其鸟苷酸环化酶路径(cyclic guanosine monophosphate,cGMP)中的抗逆态基因daf-22进行了鉴定和表达研究。[方法]根据松材线虫基因组数据设计引物克隆松材线虫Bx-Daf-22基因。进一步对Bx-Daf-22基因编码的蛋白进行系统发育分析、保守结构域分析等生物信息学分析。应用BLAST比对技术在松材线虫基因组数据中鉴定得到固醇载体蛋白SCP2同源基因,命名为Bx-Daf-22。应用PCR技术扩增Bx-Daf-22完整蛋白编码区,分析同源序列系统进化和三维结构。[结果]结果表明,Daf-22作为路径的起点是cGMP路径中一个受体蛋白,可将起始信号传递到cGMP路径的膜结合受体上,再通过胰岛素相似信号途径(insulin like signaling,Insulin/IGF)中的β-胰岛素(β-insulin,Daf-28)以及转化生长因子β路径(transforming growth factor β,TGFβ-like)中的热激蛋白90(HSP90/Daf-21)连接从而调控线虫进入抗逆态。[结论]通过结构比对及基因表达量分析表明Bx-Daf-22与秀丽线虫Daf-22具有相近的功能。Bx-Daf-22编码的蛋白质具有固醇载体蛋白SCP2构域。因此松材线虫的cGMP路径与DL3形成具有直接相关。     

三个烟草品种瞬时表达OsWAK1::GFP的差异

在研究水稻基因OsWAK1功能的过程中,利用荧光分子标记的方法,将OsWAK1与绿色荧光蛋白GFP构建为融合蛋白,利用注射法使表达OsWAK1::GFP融合蛋白的农杆菌浸入烟草叶片。通过荧光显微观察,根据烟草叶片表皮细胞中是否产生绿色荧光来判断融合蛋白是否表达。研究中同时利用了3个不同的烟草品种,利用同样的方法和操作程序,但是最后根据烟草叶片中绿色荧光的检测结果发现,不同的烟草品种对OsWAK1::GFP融合蛋白的表达差异很大。OsWAK1::GFP融合蛋白能够在心叶烟叶片中表达,却未能检测到其在本生烟和三生烟两个品种的叶片中表达。     

Ear:stem ratios in breeding populations of wheat: significance for yield improvement

Earlier studies showed that the ratio of the weight of the wheat ear to stem at anthesis (ear:stem ratio) may give a better indication of potential yield than harvest index because it is determined early in the life cycle and is not affected by post anthesis stress. These studies concluded that selection for high ear:stem ratio at anthesis may lead to further improvement in grain yield of wheat. The present work was undertaken in the field to identify lines varying in ear:stem ratio in breeding populations and to study its implications for yield improvement.At anthesis stem length, ear length, tiller number, dry weight of stem and ear and ear:stem ratio were measured in 14 crosses on F₂ single plants and F₂ derived lines grown in the F₃, F₄, and F₅ at three locations in Western Australia over four seasons. In addition, biomass, grain yield and yield components were measured on selected crosses at two locations on F₂ derived lines grown in the F₄ and F₅. There was a considerable range of ear:stem ratio between and within the crosses studied. Although ear:stem ratio was strongly correlated with stem length, there was substantial variation within stem length classes. Ear:stem ratio had a high mean broad sense heritability (82%), whereas HI, grain yield and above ground biomass had lower heritabilities, 68, 55 and 35% respectively. Ear:stem ratio was strongly correlated between generations and sites indicating stability of this character. Ear:stem ratio had a significant positive correlation with grain yield, HI, grains per ear and per m². The correlation of grain yield with HI was equal or slightly higher than that of grain yield with ear:stem ratio.Ear:stem ratio offers promise as a predictor of HI and yield potential where post-anthesis moisture stress can influence HI. Ear:stem ratio measurement is unlikely to be adopted for selection purposes in routine breeding programs, as it is laborious and time consuming. However, ear:stem ratio could be used to identify superior parental genotypes and early generation selections from special crosses in terms of its ability to partition assimilate.     

生态系统服务研究进展

通过查阅近年来国际上对生态系统服务的最新研究,在简要概述生态系统服务的产生背景及内涵的基础上,综合分析人类活动、气候变化、生物多样性与生态系统服务功能之间的相互关系,从不同尺度上探讨生态系统服务功能价值评估的研究动态,并根据以往研究工作中的重点做出展望：开展基于生态系统服务功能评价的生态学长期定位监测方法有待进一步研究;生态系统服务功能评价指标仍需进一步完善;开展干旱区的生态系统服务功能研究是新的发展方向。     

Note: Direct Impact of an Airport on Travelers' Expenditures: Methodology and Application

Economic impact studies overestimate the direct impact of an airport on travelers' expenditures. This occurs for two reasons. First, impact studies assume that the number of visitors traveling to the local area via the airport would fall to zero in the absence of the airport. Second, impact studies implicitly assume that local residents would continue to travel outside the local area in the same numbers as when the local airport is available. In other words, it is assumed that the demand for travel into the local area by visitors is perfectly elastic with respect to the time and money costs of travel, while the demand for travel by local residents is perfectly inelastic with respect to these variables. This paper develops a methodology that avoids both of these sources of error by explicitly incorporating air travel demand into the analysis. The methodology is applied to Tampa International Airport for the year 1996. It is shown that using the standard methodology would have resulted in an estimate of direct impacts sixteen times the size of the estimate made by using the methodology of this paper.