A Thionin Stain for Visualizing Bone Cells, Mineralizing Fronts and Cement Lines in Undecalcified Bone Sections

A staining method is described using thionin, for undecalcified deacrylated bone sections. RNA is stained purplish violet, allowing still active osteoblasts to be distinguished from lining cells. Staining intensity of mineralized bone is related to the degree of mineralization. Mineralizing fronts and cement lines are visualized clearly. Lamellae show an alternate pattern. Histomorphometric parameters such as osteon thickness and interstitial bone thickness can be measured without using polarized light. The mineralizing front can be assessed and expressed as a percentage of the osteoblast-covered interface between osteoid and mineralized bone. The stain is also useful for qualitative assessment of metabolic bone disease. Thionin stained sections can be kept for at least one year when stored hi the dark at 7 C.     

A physical context for gelatinous zooplankton aggregations: a review

The magnitude and extent of jellyfish blooms are influenced not only by the biology and behavior of the animal, but also by the geographic setting and physical environment. Hydrography alone is often thought to cause or favor gelatinous zooplankton aggregations, however, it is clear that interactions between biology of the animal and physics of the water are very important sources of population variations, especially at local scales. We summarize the role of physical processes and phenomena that promote aggregations of gelatinous zooplankton. We have identified and discussed a suite of physical gradients that can be perceived by gelatinous zooplankton. These include light, gravity, temperature, salinity, pressure and turbulence. A recurring theme is accumulation of jellyfish around physical discontinuities such as fronts (shelf-break, upwelling, tidal and estuarine) and pycnoclines (thermoclines and haloclines). Interestingly, there are few data to suggest that large-scale, quasi-stationary features, such as the largest oceanic fronts, serve to physically aggregate gelatinous animals at a similar scale. Rather, examples of local aggregations appear to dominate the literature. We also discuss various jellyfish behaviors that are theorized to promote aggregation, feeding and reproduction in relation to physical discontinuities.     

可持续生计研究热点与前沿的可视化分析

可持续生计目前已成为全球环境变化研究的热点领域,正日益发展为可持续性科学的重要研究范式之一。论文以Web of science核心库为数据源,应用可视化分析软件CiteS paceⅢ,采取关键词共现分析、文献共被引分析、突现词分析等方法对国际可持续生计研究现状进行系统分析。研究发现,可持续生计研究文献数量呈逐年上升趋势,主要分布在生态、环境、资源及管理相关学科;瓦赫宁恩大学、中国科学院、昆士兰大学、哥伦比亚大学、博茨瓦纳大学等研究机构表现出较强的研究实力;研究人员及机构的成规模的合作网络已经形成。Scoones I、Chambers R、Conway G、Ellis F和Ostrom E等学者及其代表作品对可持续生计理论知识基础的构建及相关研究的推进奠定了坚实的基础。生计与生态环境的相互关系一直是研究重点,交叉学科的综合集成研究将成为可持续生计研究的新热点。     

A model of a myelinated nerve axon: threshold behaviour and propagation

A model of a myelinated nerve axon is developed on the basis of FitzHugh-Nagumo dynamics under the assumption that the nodes of Ranvier are of small but finite width. It is shown that a periodic excited state may not exist if the width of the nodes is too small and the leakage across the myelin sheath is too great. The propagation of a super threshold pulse is prevented in the absence of nodes. Global stability of the resting equilibrium state is investigated as well as the propagation of wave front, type solutions.     

Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

Anguillid freshwater eels show remarkable life histories. In the Atlantic, the European eel (Anguilla anguilla) and American eel (Anguilla rostrata) undertake extensive migrations to spawn in the oceanic Sargasso Sea, and subsequently the offspring drift to foraging areas in Europe and North America, first as leaf-like leptocephali larvae that later metamorphose into glass eels. Since recruitment of European and American glass eels has declined drastically during past decades, there is a strong demand for further understanding of the early, oceanic phase of their life cycle. Consequently, during a field expedition to the eel spawning sites in the Sargasso Sea, we carried out a wide range of dedicated bio-physical studies across areas of eel larval distribution. Our findings suggest a key role of oceanic frontal processes, retaining eel larvae within a zone of enhanced feeding conditions and steering their drift. The majority of the more westerly distributed American eel larvae are likely to follow a westerly/northerly drift route entrained in the Antilles/Florida Currents. European eel larvae are generally believed to initially follow the same route, but their more easterly distribution close to the eastward flowing Subtropical Counter Current indicates that these larvae could follow a shorter, eastward route towards the Azores and Europe. The findings emphasize the significance of oceanic physical–biological linkages in the life-cycle completion of Atlantic eels.     

国际糖生物学战略布局与研究前沿分析

糖生物学与细胞信号转导、发育、免疫等许多领域相关联,是全面、深入理解生命活动所必需的。本文通过分析各国在糖生物学领域的战略布局,并使用ISI Essential Science Indicators数据库和VOS Viewer软件从定量角度分析国际糖生物学领域的研究前沿,为我国制定糖生物学研究相关战略提供借鉴。     

Feeding ecology and interannual variations in diet of southern bluefin tuna, Thunnus maccoyii, in relation to coastal and oceanic waters off eastern Tasmania, Australia

The diets of 1219 southern bluefin tuna, Thunnus maccoyii, from inshore (shelf) and offshore (oceanic) waters off eastern Tasmania were examined between 1992 and 1994. Immature fish (< 155 cm fork length) made up 88% of those examined. In all, 92 prey taxa were identified. Inshore, the main prey were fish (Trachurus declivis and Emmelichthys nitidus) and juvenile squid (Nototodarus gouldi). Offshore, the diversity was greater, reflecting the diversity of micronekton in these waters. Interestingly, macrozooplankton prey (e.g. Phronima sedentaria) were prevalent in tuna > 150 cm. The offshore tuna, when in subantarctic waters, ate relatively more squid than when in the East Australia Current. In the latter, fish and crustacea were more important, although there were variations between years. No relationship was found between either prey type or size with size of tuna. Feeding was significantly higher in the morning than at other times of the day. The mean weight of prey was significantly higher in inshore-caught tuna than in those caught offshore. We estimated that the mean daily ration of southern bluefin tuna off eastern Tasmania was 0.97% of wet body weight day⁻¹. However, the daily ration of inshore-caught tuna was ∼ 3 times higher (2.7%) than for tuna caught offshore (0.8%) indicating that feeding conditions on the shelf were better than those offshore. Our results indicate that the inshore waters of eastern Tasmania are an important feeding area for, at least, immature southern bluefin tuna. This revised version was published online in July 2006 with corrections to the Cover Date.     

Composition and distribution of zooplankton across an upwelling front on the northern Portuguese coast during summer

Zooplankton was sampled during the summer of 1995 from a grid of 34 shelf stations located off the Ria de Aveiro (northwestern Portugal), which were arranged into cross-shore transects extending either to the shelf break or to the 50 m isobath. At each station, a bongo net was hauled obliquely from close to the bottom or a maximum depth of 50 m to the surface. STD casts were made also at each station and wind data were obtained from a land station. Analysis of salinity and temperature data detected the presence of strong thermohaline stratification and a lens of reduced salinity water at the surface. A well-defined front, located at a depth of 10 to 35 m, separated cold water close to shore from warmer offshore water. Isopycnals between the front and the shore were bent towards the surface. The structure of the thermohaline features was consistent with the upwelling-favourable winds measured during the sampling period. A classification and a multivariate analysis of variance of the more abundant species showed the presence of two distinct assemblages that were separated by the front, indicating that these formations are important features structuring the zooplanktonic community of upwelling areas. The data further indicate that the zooplankton was composed of Palaeartic Atlantic and Mediterranean neritic species, and that oceanic species were absent from the samples. The absence of oceanic species is interpreted as resulting from the offshore displacement of the slope poleward flow and of the Portugal Current that takes place during the summer, as a response to upwelling-favourable winds.