Discovery of Jupiter's 'gossamer' ring

Jupiter's ring system has previously been described as being composed of a 'bright' narrow ring and an interior, vertically-extended halo. The one image which reveals this morphology most clearly is Voyager 2's parting shot of the Jupiter system, a wide-angle (WA) view of the ring ansa in forward-scattered light (FDS 20693.02). The bright ring is plainly visible, and the halo appears after slight contrast enhancement. By further enhancement of this image we have discovered an additional ring, which is far fainter than either of the (already faint) components previously identified, extending to a radius of 210,000 km.     

Arboreal arthropod community structure in an early successional coniferous forest ecosystem in western Oregon

This study was designed to characterize arboreal arthropod community structure in an early successional coniferous ecosystem. We sampled six-year-old snowbrush ( Ceanothus velutinus Dougl. ex Hook) and Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) at the H. J. Andrews Experimental Forest in western Oregon during 1982. The arthropod fauna was dominated in terms of densities by psyllids and aphids on snowbrush and by adelgids and cecidomyiids on Douglas-fir. Significant associations among taxa, e.g., positive correlation between aphids and ants, indicated trophic interactions or similar responses to host conditions. Significant seasonality was observed for individual taxa and for the community, reflecting the integration of individual life-history patterns. Significant spatial pattern (patchiness) in the arthropod community may reflect the influence of faunas on individual plants within neighborhoods and/or the influence of ant foraging patterns.     

拟南芥中一个经典阿拉伯半乳糖蛋白的亚细胞定位

为确定拟南芥中一个经典阿拉伯半乳糖蛋白(arabinogalactan-protein,AGP)的亚细胞定位,克隆了这个基因的编码区,与绿色荧光蛋白(GFP)基因构建融合表达载体,经农杆菌介导转化烟草BY-2悬浮细胞.利用激光扫描共聚焦显微镜,在稳定转化的BY-2细胞表面观察到绿色荧光.研究结果表明,此AGP分布在细胞膜表面.     

低碳锰钢中周期性带状组织

用扫描电镜和电子探针研究了低碳锰钢中的周期性带状组织，结果表明，在全部研究用钢中，钢锭经热轧后均出现这种组织，其严重程度随钢的成分而异，并随坯带加工顺序而增加，带状组织与锰的显微偏析等因素有关，适当的调整碳锰以及形成模跨铁素体带的转变产物可降低带状组织的严重程度。     

Arabinogalactan-proteins: structure, expression and function

Arabinogalactan-proteins (AGPs) are a family of extensively glycosylated hydroxyproline-rich glycoproteins that are thought to have important roles in various aspects of plant growth and development. After a brief introduction to AGPs highlighting the problems associated with defining and classifying this diverse family of glycoproteins, AGP structure is described in terms of the protein component (including data from molecular cloning), carbohydrate component, processing of AGPs (including recent data on glycosylphosphatidylinositol membrane anchors) and overall molecular shape. Next, the expression of AGPs is examined at several different levels, from the whole plant to the cellular levels, using a variety of experimental techniques and tools. Finally, AGP function is considered. Although the existing functional evidence is not incontrovertible, it does clearly point to roles for AGPs in vegetative, reproductive, and cellular growth and development as well as programmed cell death and social control. In addition and most likely inextricably linked to their functions, AGPs are presumably involved in molecular interactions and cellular signaling at the cell surface. Some likely scenarios are discussed in this context. AGPs also have functions of real or potential commercial value, most notably as emulsifiers in the food industry and as potential immunological regulators for human health. Several important questions remain to be answered with respect to AGPs. Clearly, elucidating the unequivocal functions of particular AGPs and relating these functions to their respective structures and modes of action remain as major challenges in the years ahead.