土壤干旱胁迫下非水力根信号调控夏玉米气体交换对大气环境的响应

对不同程度土壤干旱胁迫下夏玉米非水力根信号的产生以及气体交换过程对大气环境的响应进行了试验研究。充足底墒播种后采用3个土壤水分处理等级(0~200cm土壤相对湿度为>80%、60%~70%、40%~50%,代号为W T1、W T2和W T3)。生育期内遮去自然降水。试验结果表明,在拔节期轻度和中度土壤干旱胁迫的情况下,玉米根系合成大量ABA传输到地上部分,参与控制气孔开度和气体交换过程对大气环境变化的响应并调节水分消耗。在日变化过程中,当光强和水汽压亏缺较高时,由于蒸腾速率较高,非水力根信号物质向冠层的传输速率也较高,ABA在叶片中的累积影响了气孔开张对光强响应的敏感度,气孔开度受到抑制,并且随着ABA累积和浓度的增加,气孔抑制作用越强;在水汽压亏缺较低的情况下,非水力根信号物质向冠层的传输速率较低,ABA的代谢过程以及再分配过程能够保证这种信号物质保持在低水平,从而保证一定程度的气孔开度和光合、蒸腾速率。这种策略能够使夏玉米在轻、中等干旱条件下保证最大的光合作用,同时在可能的胁迫情况下降低蒸腾作用以提高水分利用效率。     

人工与自然恢复条件下地被层优势种大羽藓的遗传多样性比较

基于随机扩增多态性DNA(RAPD)方法比较了川西米亚罗地区3个人工云杉林样地和3个天然次生林样地大羽藓(Thuidium cym bifolium)种群的遗传多样性及分化程度。人工林种群的平均多态位点百分比(PPL)为12.7%,Ne i’s基因多样性(HE)为0.042,Shannon’s信息指数(S)为0.064,种群内遗传一致度(I)为0.952;天然次生林种群则依次为10.0%、0.027、0.043和0.960。人工林种群和天然次生林种群Gst分别为0.592和0.702,Fst分别为0.639和0.695;结合UPGMA聚类和PCA分析,发现种群间的基因交流极少。单因素方差分析显示,人工林下大羽藓种群的遗传多样性水平显著高于天然次生林下种群(p<0.05),表明在皆伐迹地上通过人工造林能有效地促进林下物种遗传多样性的恢复。     

基于核糖体DNA联合序列的天牛总科高阶元分子系统学研究

【目的】利用核糖体DNA联合序列探讨天牛总科高阶元分子系统发育。【方法】本研究采用分子标记技术,分析测定了63种天牛核糖体28S rDNA D2和D3区以及18S rDNA V4和V7区的DNA序列,并采用邻接法、最大似然法和贝叶斯推论法分别构建了天牛总科2科6亚科63种的分子进化系统。【结果】序列联合比对分析,最终得到1 404 bp的联合数据组,其中可变位点446个（32.0%）,保守位点958（68.0%）,转换/颠换的平均值（R值）为1.73。28S rDNA和18S rDNA以及联合序列的饱和度分析显示碱基突变未达到饱和,说明这些序列适合于分子进化树的构建。利用不同系统发育重建方法得到进化树具有相似拓扑结构,结果支持沟胫天牛亚科、花天牛亚科和天牛亚科为单系群,这与形态学分类结果相似;狭胸天牛独立成为亚科得到了支持。【结论】利用28S rDNA D2和D3区以及18S rDNA V4和V7区联合序列成功构建出了天牛总科高阶元的系统发育树。研究表明联合序列分析是探讨天牛高阶元分类的有效的方法。     

AVP and Glu systems interact to regulate levels of anxiety in BALB/cJ mice

While the roles of glutamic acid(Glu), arginine vasopressin(AVP) and their respective receptors in anxiety have been thoroughly investigated, the effects of interactions among Glu, N-methyl-D-aspartic acid(NMDA) receptor, AVP and a-amino-3-hydroxy-5-methylisoxazole-4-propionic acid(AMPA) receptor on anxiety are still unclear. In the present study, the agonist and antagonist of the NMDA receptor and AMPA receptor, as well as the antagonist of AVP V1 receptor(V1aR) were introduced into BALB/cJ mice by intracerebroventricular microinjection, and the anxiety-like behaviors of the mice were evaluated by open field and elevated plus-maze tests. Compared with C57BL/6 mice, BALB/cJ mice displayed higher levels of anxiety-like behavior. Significant anxiolytic effects were found in the NMDA receptor antagonist(MK-801) and the AMPA receptor or V1 aR antagonist(SSRI49415), as well as combinations of AVP/MK-801 and SSRI49415/DNQX. These results indicated that anxiety-like behaviors expressed in BALB/CJ mice may be due to a coordination disorder among glutamate, NMDA receptor, AMPA receptor, AVP and V1 aR, resulting in the up-regulation of the NMDA receptor and V1 aR and down-regulation of the AMPA receptor. However, because the AMPA receptor can execute its anxiolytic function by suppressing AVP and V1 aR, we cannot exclude the possibility of the NMDA receptor being activated by AVP acting on V1 aR.     

Urban Forest Justice and the Rights to Wild Foods, Medicines, and Materials in the City

Urban forests are multifunctional socio-ecological landscapes, yet some of their social benefits remain poorly understood. This paper draws on ethnographic evidence from Seattle, Washington to demonstrate that urban forests contain nontimber forest products that contribute a variety of wild foods, medicines, and materials for the wellbeing of urban residents. We show that gathering wild plants and fungi in urban forests is a persistent subsistence and livelihood practice that provides sociocultural and material benefits to city residents, and creates opportunities for connecting with nature and enhancing social ties. We suggest that an orientation toward human-nature interactions in cities that conceptualizes the gathering of forest products as a legitimate social benefit may support and expand urban forest justice. Urban forest justice recognizes the rights of local people to have control over their own culturally appropriate wild food and health systems, including access to natural resources and to the decision-making processes affecting them.     

生物大分子相分离在植物中的研究进展

细胞中存在种类繁多的无膜细胞器,在感知环境信号,基因表达调控,RNA加工等过程中发挥了重要的作用,而生物大分子相分离被证明是无膜细胞器形成的主要方式。文章介绍了生物大分子相分离的概念与特征,总结了有关相分离在植物对环境信号响应中的研究进展,并对相分离在植物中的生物学功能进行了分类,以期解析相分离在植物生长发育和逆境适应中的作用机理,揭示植物无膜细胞器的本质与功能。     

Waterfowl distribution and productivity in the Prairie Pothole Region of Canada: tools for conservation planning

Species conservation requires an understanding of the factors and interactions affecting species distribution and behavior, habitat availability and use, and corresponding vital rates at multiple temporal and spatial scales. Opportunities to investigate these relationships across broad geographic regions are rare. We combined long-term waterfowl population surveys, and studies of habitat use and breeding success, to develop models that identify and incorporate these interactions for upland-nesting waterfowl in the Prairie Pothole Region (PPR) of Canada. Specifically, we used data from the annual Waterfowl Breeding Population and Habitat Survey (1961–2009) at the survey segment level and associated habitat covariates to model and map the long-term average duck density across the Canadian PPR. We analyzed nest location and fate data from approximately 25,000 duck nests found during 3 multi-year nesting studies (1994–2011) to model factors associated with nest survival and habitat selection through the nesting season for the 5 most common upland nesting duck species: mallard (Anas platyrhynchos), gadwall (Mareca strepera), blue-winged teal (Spatula discors), northern shoveler (Spatula clypeata), and northern pintail (Anas acuta). Duck density was highly variable across the Canadian PPR, reflecting positive responses to local wetland area and count, and amounts of cropland and grassland, a regional positive response to latitude, and a negative response to local amounts of tree cover. Nest survival was affected by temporal and spatial variables at multiple scales. Specifically, nest survival demonstrated interactive effects among species, nest initiation date, and nesting cover type and was influenced by relative annual wetness, population density, and surrounding landscape composition at landscape scales, and broad geographic gradients (east-west and north-south). Likewise, species-specific probability of nest habitat selection was influenced by timing of nest initiation, population density, relative annual wetness, herbaceous cover, and tree cover in the surrounding landscape, and location within the Canadian PPR. We combined these models, with estimates of breeding effort (nesting, renesting, and nest attempts) from existing literature, in a stochastic conservation planning model that estimates nest distribution and success given spatiotemporal variation in duck density, habitat availability, and influential covariates. We demonstrate the use of this model by examining various conservation planning scenarios. These models allow estimation of local, landscape, and regional influence of conservation investments and other landscape changes on the productivity of breeding duck populations across the PPR of Canada. These models lay the groundwork for the incorporation of conservation delivery costs for full return-on-investment analyses and scenario analyses of climate, habitat, and land use change in regional and continental population models.     

Lesions confined to the ventromedial hypothalamus decrease the frequency of coital contacts in female rats

Ovariectomized female rats received either bilateral radiofrequency lesions of the ventromedial nucleus of the hypothalamus (VMH) or control treatments and were tested for copulatory activity following either estrogen (E) alone, or E plus progesterone (P) administration. In separate experiments the females were tested in two testing apparatuses both of which allowed the test females to control their contacts with sexually active males. One of the testing apparatuses also allowed the females to control their contacts with sexually inactive males and ovariectomized females. Females receiving VMH lesions engaged in fewer coital contacts with sexually active males than sham-operated females in the E plus P condition. Lesioned females also tended to spend less time with sexually active males than did sham operates in both the E and E plus P hormonal conditions. The VMH-lesioned females did not differ from the sham-operated females in the ability to display lordosis during the coital contacts or the frequency and duration of visits to the inactive males or ovariectomized females. The sham-operated females did have some transitory alterations in copulatory behavior in comparison to unoperated control females.