Phenolics and Proteins Affecting Palatability of Spartina Leaves to the Gastropod Littoraria irrorata

Along the southeastern coast of the United States, the saltmarsh periwinkle Littoraria irrorata is a major consumer of Spartina alterniflora . It prefers to feed on dead rather than living plants. During senescence and early decay, S. alterniflora leaves become colonized by fungi, their phenolic content declines, and their lipid content increases. In this study, the food preferences of L. irrorata were assessed by offering intact leaves or leaf powder suspended in agar. Relative palatabilities were determined by measuring the weight loss of intact leaves, or by estimating the area of feeding marks left on the surface of leaf powder suspensions. Both techniques demonstrated a clear preference for standing dead rather than yellow-green (senescent) leaves. Yellow-green leaves contained methanol-soluble feeding deterrents. A comparable deterrent effect could be achieved by adding ferulic acid, a phenolic compound common in yellow-green S. alterniflora , to leaf powder. The deterrent effects of methanol extracts or ferulic acid could be neutralized by simultaneously adding fungal mycelium or BSA. Littoraria irrorata preferred leaves colonized by fungi or bacteria over sterile leaves. When offered a choice of sterile leaves colonized by different fungi, the results were variable. In one experiment, L. irrorata clearly preferred one of three leaffungus combinations. The same preference was shown after the food items were treated with methanol/chloroform to remove lipids. In a second experiment with four other fungal strains, there was only a clear preference for one leaf-fungus combination after removal of lipids. The results suggest that the saltmarsh periwinkle prefers S. alterniflora leaves with low concentrations of phenolic deterrents, most likely ferulic acid, and with sufficient fungal biomass. The food choice may be influenced to a smaller degree by fungal components, which, depending on the species or strain, may be lipids or other compounds.     

海产动物选择育种的研究进展

随着养殖业的不断发展,优良品种的选育已日趋重要.本文对国外海产动物选择育种的进展情况作初步介绍和评价,以便大家对当前国际上在这方面的研究进展有所了解,同时也希望对国内这方面工作的开展起到一定的促进作用.     

Nutrient Enrichments of Waters of "Golfo de San Jose" (Argentina, 42 oS), Growth and Species Selection of Phytoplankton

Abstract. Coastal Patagonian sea waters had been differentially nutrient-enriched to determine (i) the magnitude of the algal biomass supported and (ii) which species were able to best compete for the available nutrients. Nitrogen was found to be the nutrient limiting growth of the natural phytoplankton population. The addition of NO₃ at 25 μg at 1^-1 led to a 10 to 30 μg 1^-1 increase in chlorophyll a in all but those treatments containing trace metal additions. The best yield coefficients were obtained when a chelator (EDTA) was added with NO₃. A pool of nine diatom species were common in the N0₃ supplemented waters and the addition of vitamins along with NO₃ allowed two of the nine species to dominate.     

除草剂San9785在高EPA后棘藻品系筛选中的应用

后棘藻(Ellipsoidion sp.)是一种高脂海洋微藻,采用微生物筛选平板的方法,利用多不饱和脂肪酸EPA合成的阻断剂——除草剂San9785对紫外线诱变的后棘藻细胞进行了高EPA个体的筛选,气相分析结果显示,在检测的8株筛选品系中,5株EPA含量高于出发藻种,平均提高了121.6%,另3株EPA含量低于出发藻种,平均降低的量为12.6%,EPA含量最高的品系达到总脂肪酸的26.22%,比出发藻种提高了212%.提示除草剂San9785可以作为一种高效筛选压力,选育多不饱和脂肪酸含量丰富的微藻品系.     

基于FY-4A卫星探测区域模式背景误差和观测误差估计的长波红外通道选择研究

中国新一代静止气象卫星风云四号A星（FY-4A）上搭载的干涉式大气垂直探测仪GIIRS（Geostationary Interferometric Infrared Sounder）是世界上首台在静止轨道运行的高光谱红外探测仪器,拥有1650个通道,其中长波通道689个,中波通道961个。由于计算机存储能力、数据传输和变分同化时效性等限制,目前很难在业务环境中同化全部通道,并且多通道卫星信息往往存在一定的空间相关和光谱相似,故在实际应用中必须降低高光谱资料的通道维数,去除数据冗余和观测相关性,挑选出对特定目标起主要作用的通道子集,进而利用有限的通道来最大限度地提供观测信息。考虑GRAPES（Global/Regional Assimilation and Prediction Enhanced System）数值预报系统估计得到的FY-4A观测范围内的背景误差协方差矩阵,并且在GIIRS观测误差后验重估计的基础上,结合通道权重函数峰值和信息熵分步迭代法对其长波通道进行了通道选择研究和试验。结果表明,在给定选择通道个数时,权重函数法和信息熵方法得到的通道组合进行温度和湿度误差分析时误差整体比单一方法小,在给定通道个数（40个）少于单一方案（50个）时,误差分析结果相当。GIIRS最优通道选择的研究为该资料的同化应用建立了基础。      

一种改进的组合定权的指纹定位算法

室内场景复杂、WiFi信号不稳定等因素,造成基于信号空间K最近邻法的WiFi指纹定位算法匹配的邻近点会出现偏差,使用偏差较大的点计算待定点位置会直接影响定位结果。本文提出了一种改进的组合定权的指纹定位算法,对K个邻近点的几何结构进行分析,剔除其中偏离邻近点几何中心较远的点后,同时分析匹配邻近点中心同待定点几何位置存在理论上的关联,利用选择后的邻近点与其中心点的几何距离、待定点与指纹点欧氏距离组合定权,加权求取坐标。与KNN、WKNN算法定位结果分别进行比较,表明该方法提高了定位准确性和精度。