Asteroid and Ophiuroid Trace Fossils from the Lower Cretaceous of Chile

Abundant asterozoan trace fossils in the Lower Cretaceous Apeleg Formation of southern Chile were produced by the infilling of traces made by asteroids and ophiuroids on a muddy surface. Most are preserved as hypichnial ridges formed as casts on the bottom of fine-grained sandstone laminae. Star-shaped Asteriacites lumbricalis are interpreted as the infillings of shallow excavations made by asteroids. Hook-shaped and sinuous ridges of the newly defined ichnogenus and ichnospecies Ophioichnus aysenensis are interpreted as the casts of imprints made by the walking action of the arms of ophiuroids. Deposition probably took place in an offshore tide-swept marine shelf environment. In life the animals formed an assemblage equivalent to echinoderm aggregations on the modern sea floor.     

Regeneration of a complex of structures of the ophiuroid <Emphasis Type="Italic">Amphipholis kochii</Emphasis> Lütken, 1872 (Ophiurae) after disk autotomy

Regeneration of structures (genital bars and ligaments) which enables ophiuroids to throw away the aboral part of the disc was studied in this work. The succession of disc separation during autotomy has been fixed. It has been revealed that upon restoration of genital bars and ligaments regeneration occurs due to migration of cells from tissues remaining after autotomy, but not due to differentiation of cell elements. The cell sources of regeneration of the studied structures are fibroblasts and sclerocytes.     

Luminous capabilities and life-history traits of the polychromatic ophiuroid Amphipholis squamata in two isolated populations from Oliveri-Tindari lagoon system,Sicily

Amphipholis squamata is a small ophiuroid with a worldwide distribution except for Polar regions. Global populations of A. squamata are morphologically uniform but inter- and intrapopulational variability occurs at levels from the population to the genotype. The species is polychromatic and two colour varieties (dark-brown and spotted) from two adjacent populations (separated from each other for only 20 years) in a lagoonal system (Sicily) were compared using bioluminescence and life-history traits as indicators of variability. The dark-brown variety was dominant in Lago Nuovo and the spotted one was dominant in Porto Vecchio. Important variations were observed within populations, however, there were significant differences in life-history traits and luminous capabilities between the dark-brown and spotted varieties. The dark-brown variety invested more energy in somatic growth than reproduction (1 cohort each year and growth rate of 0.279 mm each month), whereas energy was devoted mainly to reproduction in the spotted variety (4 cohorts each year and growth rate of 0.171 mm each month). The chronology of the life cycles was completely different between the two varieties. Fertilization occurred mainly in spring for the spotted but only in autumn for the dark-brown. Recruitment occurred mainly in autumn for spotted and in spring for dark-brown individuals. Finally, significant differences were observed for maximal intensity of emitted light and kinetic parameters between the two varieties.     

The Preparation of N-Methylpyrrolidine Rings by 1,3-Dipolar Cycloaddition Reaction

Synthesis of tetrasaccharide portion of ganglioside HPG-1 is described. The tetrasaccharide sequence, Fuc-α(1,8)-Neu5Gc-α(2,4)-Neu5Ac-α(2,6)-Glc, was successfully assembled by a linear strategy, in which the 1,5-lactamized sialyl galactose acceptor and the 8-O-Lev-N-Troc-sialic acid donor were exploited as key units.     

Tissue and spine regeneration in the temperate sea urchin Psammechinus miliaris

The tissue regenerative capabilities of echinoderms are well known at the morphogenic level, yet significant knowledge gaps remain concerning the molecular control of these processes. This pilot study assayed two pharmacological agents (vincristine sulphate and DAPT) injected directly into the body cavity of specimens of the temperate echinoid Psammechinus miliaris which had had their spines and tube feet deliberately amputated. Vincristine sulphate, which is a generalised mitotic inhibitor, was used as a positive control, whereas DAPT is a y-secretase inhibitor known to block sea urchin embryo development and suppress echinoid regeneration by interfering with Notch signalling pathways. Significant differences in regeneration rate became apparent in both treatments 29 days post amputation with both inhibitors slowing regeneration of tube feet (0.6 μg/g vincristine sulphate by 44.4% relative to controls; 4 μg/g DAPT by 55.6% relative to controls) and spines (0.6 μg/g vincristine sulphate by 53.3% relative to controls; 4 μg/g DAPT by 66.7% relative to controls). Vincristine sulphate was more clearly dose-dependent than DAPT. This initial inhibition-based approach allows inferences to be made concerning possible molecular pathways controlling regeneration within P. miliaris and adds further support to the hypothesis that Notch signalling plays a major role in regulating regeneration in echinoids.     

棘皮动物免疫学研究进展

棘皮动物属原始后口动物、无脊椎动物的最高等类群,它处于由无脊椎动物向脊椎动物开始分支进化的阶段．研究棘皮动物的免疫功能和作用机理,对从比较免疫学角度探讨动物免疫系统进化过程有承前启后的重要意义．因此,有必要对棘皮动物的免疫学研究进展作一个较全面的综述,并理清未来的研究热点和方向．棘皮动物与其他无脊椎动物一样具有先天性免疫系统,但未发现脊椎动物所具有的获得性免疫．其免疫应答是由参与免疫反应的效应细胞——体腔细胞和多种体液免疫因子共同介导的．比较免疫学分析表明,棘皮动物存在脊椎动物补体系统的替代途径和凝集素途径,但未发现经典途径和明确的终端途径．棘皮动物先天性免疫系统存在数量庞大的基因家族．今后应加强对未知免疫相关基因、蛋白质、信号传导途径及效应分子的研究,回答免疫系统的起源、功能和进化等问题．     

国内外产业共生网络研究比较述评

产业共生网络是指基于物质及能量交换以及知识及基础设施共享而形成的在不同产业主体之间的合作共赢网络,是产业转型升级的重要保障。作为产业共生的运作方式,产业共生网络的研究国外从20世纪90年代开始从概念到实例就展开了一系列探讨,国内自2002年也开始在网络结构等方面开展相关研究。尤其在2008年以后,产业共生网络的研究方向不断拓宽,研究成果丰富多样。为明晰国内外产业共生网络研究的发展态势,促进产业共生网络理论体系的发展并使其得到有效应用。本文从共生网络内涵、结构、功能及评价、演化、管理调控等方面比较分析了国内外产业共生网络的研究进展,并对产业共生网络的发展前景做了展望。未来产业共生网络研究在不同尺度的比较及推演、数据信息平台的搭建以及产业共生网络演化模拟及管理调控的耦合等方面需重点关注。     

Phylogenomic analysis of echinoderm class relationships supports Asterozoa

While some aspects of the phylogeny of the five living echinoderm classes are clear, the position of the ophiuroids (brittlestars) relative to asteroids (starfish), echinoids (sea urchins) and holothurians (sea cucumbers) is controversial. Ophiuroids have a pluteus-type larva in common with echinoids giving some support to an ophiuroid/echinoid/holothurian clade named Cryptosyringida. Most molecular phylogenetic studies, however, support an ophiuroid/asteroid clade (Asterozoa) implying either convergent evolution of the pluteus or reversals to an auricularia-type larva in asteroids and holothurians. A recent study of 10 genes from four of the five echinoderm classes used ‘phylogenetic signal dissection’ to separate alignment positions into subsets of (i) suboptimal, heterogeneously evolving sites (invariant plus rapidly changing) and (ii) the remaining optimal, homogeneously evolving sites. Along with most previous molecular phylogenetic studies, their set of heterogeneous sites, expected to be more prone to systematic error, support Asterozoa. The homogeneous sites, in contrast, support an ophiuroid/echinoid grouping, consistent with the cryptosyringid clade, leading them to posit homology of the ophiopluteus and echinopluteus. Our new dataset comprises 219 genes from all echinoderm classes; analyses using probabilistic Bayesian phylogenetic methods strongly support Asterozoa. The most reliable, slowly evolving quartile of genes also gives highest support for Asterozoa; this support diminishes in second and third quartiles and the fastest changing quartile places the ophiuroids close to the root. Using phylogenetic signal dissection, we find heterogenous sites support an unlikely grouping of Ophiuroidea + Holothuria while homogeneous sites again strongly support Asterozoa. Our large and taxonomically complete dataset finds no support for the cryptosyringid hypothesis; in showing strong support for the Asterozoa, our preferred topology leaves the question of homology of pluteus larvae open.