Seawater chemistry and early carbonate biomineralization

The first appearances of aragonite and calcite skeletons in 18 animal clades that independently evolved mineralization during the late Ediacaran through the Ordovician (approximately 550 to 444 million years ago) correspond to intervals when seawater chemistry favored aragonite and calcite precipitation, respectively. Skeletal mineralogies rarely changed once skeletons evolved, despite subsequent changes in seawater chemistry. Thus, the selection of carbonate skeletal minerals appears to have been dictated by seawater chemistry at the time a clade first acquired its mineralized skeleton.     

A Cretaceous scleractinian coral with a calcitic skeleton

It has been generally thought that scleractinian corals form purely aragonitic skeletons. We show that a well-preserved fossil coral, Coelosmilia sp. from the Upper Cretaceous (about 70 million years ago), has preserved skeletal structural features identical to those observed in present-day scleractinians. However, the skeleton of Coelosmilia sp. is entirely calcitic. Its fine-scale structure and chemistry indicate that the calcite is primary and did not form from the diagenetic alteration of aragonite. This result implies that corals, like other groups of marine, calcium carbonate-producing organisms, can form skeletons of different carbonate polymorphs.     

Biomechanics of mammalian terrestrial locomotion

Mammalian skeletons experience peak locomotor stresses (force per area) that are 25 to 50% of their failure strength, indicating a safety factor of between two and four. The mechanism by which animals achieve a constant safety factor varies depending on the size of the animal. Over much of their size (0.1 to 300 kilograms), larger mammals maintain uniform skeletal stress primarily by having a more upright posture, which decreases mass-specific muscle force by increasing muscle mechanical advantage. At greater sizes, increased skeletal allometry and decreased locomotor performance likely maintain stresses constant. At smaller sizes, skeletal stiffness may be more critical than strength. The decrease in mass-specific muscle force in mammals weighing 0.1 to 300 kilogram indicates that peak muscle stresses are also constant and correlates with a decrease in mass-specific energy cost of locomotion. The consistent pattern of locomotor stresses developed in long bones at different speeds and gaits within a species may have important implications for how bones adaptively remodel to changes in stress.     

Evolutionary exploitation of design options by the first animals with hard skeletons

The set of viable design elements available for animals to use in building skeletons has been fully exploited. Analysis of animal skeletons in relation to the multivariate, theoretical "Skeleton Space" has shown that a large proportion of these options are used in each phylum. Here, we show that structural elements deployed in the skeletons of Burgess Shale animals (Middle Cambrian) incorporate 146 of 182 character pairs defined in this morphospace. Within 15 million years of the appearance of crown groups of phyla with substantial hard parts, at least 80 percent of skeletal design elements recognized among living and extinct marine metazoans were exploited.     

Origin of whales from early artiodactyls: hands and feet of Eocene Protocetidae from Pakistan

Partial skeletons of two new fossil whales, Artiocetus clavis and Rodhocetus balochistanensis, are among the oldest known protocetid archaeocetes. These came from early Lutetian age (47 million years ago) strata in eastern Balochistan Province, Pakistan. Both have an astragalus and cuboid in the ankle with characteristics diagnostic of artiodactyls; R. balochistanensis has virtually complete fore- and hind limbs. The new skeletons are important in augmenting the diversity of early Protocetidae, clarifying that Cetacea evolved from early Artiodactyla rather than Mesonychia and showing how early protocetids swam.     

Light-directed, spatially addressable parallel chemical synthesis

Solid-phase chemistry, photolabile protecting groups, and photolithography have been combined to achieve light-directed, spatially addressable parallel chemical synthesis to yield a highly diverse set of chemical products. Binary masking, one of many possible combinatorial synthesis strategies, yields 2n compounds in n chemical steps. An array of 1024 peptides was synthesized in ten steps, and its interaction with a monoclonal antibody was assayed by epifluorescence microscopy. High-density arrays formed by light-directed synthesis are potentially rich sources of chemical diversity for discovering new ligands that bind to biological receptors and for elucidating principles governing molecular interactions. The generality of this approach is illustrated by the light-directed synthesis of a dinucleotide. Spatially directed synthesis of complex compounds could also be used for microfabrication of devices.     

龙里瘰螈骨骼系统的研究

采用骨骼标本常规制作方法,对龙里瘰螈(Paramesotriton longliensis)的骨骼系统做了较全面的观察研究,对各骨骼的形态、位置及相应骨块的关系进行了详细描述;并将龙里瘰螈与尾斑瘰螈(P.caudopunctatus)、中国瘰螈(P.chinensis)、香港瘰螈(P.hongkongensis)、广西瘰螈(P.guangxiensis)和织金瘰螈(P.zhijinensis)进行了部分属间和种间的比较.可为瘰螈属的分类、演化等方面的研究提供基础资料.     

Phaeodarian skeletons: their role in silica transport to the deep sea

The skeletons of phaeodarian Radiolaria transport and redistribute silica to the tropical deep oceans by dissolving in the water column and on the sea floor. The skeletons are initially solid but within a few days to months become progressively more porous while settling through the water column. Phaeodarian Radiolaria are rarely preserved in the bottom sediments; in contrast, polycystine Radiolaria are the dominant Radiolaria preserved in the fossil record. This preservational difference may be due to differences in skeletal constituents.     

四川裂腹鱼与昆明裂腹鱼骨骼系统的比较研究

分别利用常规方法和透明骨法制备四川裂腹鱼和昆明裂腹鱼的骨骼标本,对这两种裂腹鱼的骨骼系统进行比较分析。结果表明,四川裂腹鱼与昆明裂腹鱼骨骼系统间的差异较小,可能是种间亲缘关系较近的缘故。这两种裂腹鱼在某些骨骼如齿骨、前颌骨、前鳃盖骨上表现出一些明显的差异,这些特征可以作为种间的鉴别特征。     

Skeletal low-magnesium calcite in living scleractinian corals

The skeletons of living specimens of the scleractinian coral Porites lobata have been found to contain up to 46 +/- 5 percent low-magnesium calcite even though free of gross detrital inclusions and boring or encrusting organisms. The calcite crystals occur in the interior of skeletal structures, have dimensions of 20 micrometers or less, and are surrounded by typical aragonite needles. Biogenic deposition seems to be the most likely source of the calcite, although the evidence does not rule out diagenesis of metastable.     

Insect juvenile hormone: activity of selected terpenoid compounds

A nuimber of compounds with terpenoid skeletons attached to various functional groups were prepared and tested for their effects as a juvenile hormone in the yellow mealworm Tenebrio molitor. Several of these compounds showed high activity.     

Sea urchin spine calcite forms via a transient amorphous calcium carbonate phase

The skeletons of adult echinoderms comprise large single crystals of calcite with smooth convoluted fenestrated morphologies, raising many questions about how they form. By using water etching, infrared spectroscopy, electron diffraction, and environmental scanning electron microscopy, we show that sea urchin spine regeneration proceeds via the initial deposition of amorphous calcium carbonate. Because most echinoderms produce the same type of skeletal material, they probably all use this same mechanism. Deposition of transient amorphous phases as a strategy for producing single crystals with complex morphology may have interesting implications for the development of sophisticated materials.     

Chimeras of two isoprenoid synthases catalyze all four coupling reactions in isoprenoid biosynthesis

The carbon skeletons of over 55,000 naturally occurring isoprenoid compounds are constructed from four fundamental coupling reactions: chain elongation, cyclopropanation, branching, and cyclobutanation. Enzymes that catalyze chain elongation and cyclopropanation are well studied, whereas those that catalyze branching and cyclobutanation are unknown. We have catalyzed the four reactions with chimeric proteins generated by replacing segments of a chain-elongation enzyme with corresponding sequences from a cyclopropanation enzyme. Stereochemical and mechanistic considerations suggest that the four coupling enzymes could have evolved from a common ancestor through relatively small changes in the catalytic site.     

Strontium-calcium thermometry in coral skeletons

The strontium to calcium ratio of skeletal aragonite in three genera of reef-building corals varies as a simple function of temperature and the strontium to calcium ratio of the incubation water. The strontiumlcalcium distribution coefficients of coral aragonite apparently differ from the corresponding coefficient of inorganically precipitated aragonite. With some care, coral skeletons can be used as recording thermometers.     

Early Adaptive Radiation of Birds: Evidence from Fossils from Northeastern China

Late Jurassic and Early Cretaceous birds from northeastern China, including many complete skeletons of Confuciusornis, provide evidence for a fundamental dichotomy in the class Aves that may antedate the temporal occurrence of the Late Jurassic Archaeopteryx. The abundance of Confuciusornis may provide evidence of avian social behavior. Jurassic skeletal remains of an ornithurine bird lend further support to the idea of an early separation of the line that gave rise to modern birds. Chaoyangia, an ornithurine bird from the Early Cretaceous of China, has premaxillary teeth.     

Hierarchical structure in polymeric materials

The diversity of monomers available for synthesis of high polymers makes it possible to prepare a wide variety of long-chain macromolecular compounds. It is instructive to consider a hierarchical organization of structure in polymers at four successive levels--the molecular, nano-, micro-, and macrolevels--and to examine how interactions at and between these various levels of structure have important and often quite specific influences. Examples are drawn from semicrystalline polymers with flexible chains, liquid-crystalline polymers composed of rigid macromolecules, and amorphous polymers. Structural hierarchies in biocomposite systems are also discussed, particularly in soft connective tissues such as tendon and intervertebral disk.     

The initial domestication of goats (Capra hircus) in the Zagros mountains 10,000 years ago

Initial goat domestication is documented in the highlands of western Iran at 10,000 calibrated calendar years ago. Metrical analyses of patterns of sexual dimorphism in modern wild goat skeletons (Capra hircus aegagrus) allow sex-specific age curves to be computed for archaeofaunal assemblages. A distinct shift to selective harvesting of subadult males marks initial human management and the transition from hunting to herding of the species. Direct accelerator mass spectrometry radiocarbon dates on skeletal elements provide a tight temporal context for the transition.     

Peptides enhance magnesium signature in calcite: insights into origins of vital effects

Studies relating the magnesium (Mg) content of calcified skeletons to temperature often report unexplained deviations from the signature expected for inorganically grown calcite. These "vital effects" are believed to have biological origins, but mechanistic bases for measured offsets remain unclear. We show that a simple hydrophilic peptide, with the same carboxyl-rich character as that of macromolecules isolated from sites of calcification, increases calcite Mg content by up to 3 mole percent. Comparisons to previous studies correlating Mg content of carbonate minerals with temperature show that the Mg enhancement due to peptides results in offsets equivalent to 7 degrees to 14 degrees C. The insights also provide a physical basis for anecdotal evidence that organic chemistry modulates the mineralization of inorganic carbonates and suggest an approach to tuning impurity levels in controlled materials synthesis.     

江苏省天王镇磨盘山金蝉花分离菌株鉴定及系统发育分析

蝉花是一种名贵的传统中药,其分离物多样性丰富,不同菌株的药理作用及生物活性物质含量差异明显,因此,分离物的确证是蝉花研究的关键环节.对江苏省句容市天王镇磨盘山采集的金蝉花标本分离物进行菌落形态、产孢结构观察,并依据ITS区序列进行系统发育分析,确定为蝉棒束孢菌的不同地理株.该研究对于扩大传统中药资源,进一步深入研究该菌株的药理作用及活性成分具有重要意义.     

药用植物基因组学研究进展

药用植物代表了最古老的药物形式,在许多国家的传统医学中使用数千年.药用植物是重要的自然资源,发展中国家高达80％的人口主要依赖植物来源的药物,全世界对草药的需求正在逐年递增,预计到2050年将达到5万亿美元,药用植物及其衍生物的大规模生产是不可避免的发展趋势.现代测序技术的飞速发展促进了药用植物基因组学的研究,基于基因组学的跨学科研究以及DNA和RNA、代谢组学和蛋白质组学的高通量数据分析,药用植物在代谢途径/酶、代谢物、基因、基因网络和蛋白质-蛋白质相互作用等研究领域取得突破.结合本团队相关研究工作对药用植物基因组学的最新研究进展进行综述,涉及利用结构基因组学和功能基因组学揭示各种药用植物的基因组序列信息、物种间进化、分子化合物动态变化以及药用成分合成等方面,这些数据为重要药材资源的分子辅助育种、基因组编辑以及对活性化合物化学多样性分子机制的理解提供了重要的理论基础.许多药材的植物化学成分和潜在的健康益处尚未得到研究或仍需要更深入地研究,药用植物的未来充满未知、希望,甚至惊喜.鉴于物种的多样性、环境因素的复杂性以及药用植物的全球分布,结合基因组学加强研究工作以开发新的和改良的药用植物品种势在必行.