房室海绵化石的微机研究:性状演化

利用微机对房室海绵进行了１）属的清理工作，２）标准化术语的建立与属的标准化术语描述，３）建数据库，４）性状的统计分析。并发现了房室海绵出水管类型、房室排列方式、房室充填物类型、孔和管、体型和房室形态方面的六大演化趋向。     

贵州罗甸干田坳晚二叠世生物礁基本特征研究*

通过综合岩相和生物群落特征对贵州罗甸干田坳晚二叠世生物礁进行分析,将研究区划分出三期造礁旋回。对造礁海绵在三个造礁阶段,以及礁前砾屑岩的成分面积进行统计,计算出各阶段的造礁成分组成状况,还原当时的造礁群落。共鉴定出纤维海绵纲3科4属,房室海绵纲9科10属和硬海绵纲2科2属。数据表明自始至终纤维海绵纲的小领针海绵属都为造礁群落里的优势生物,其中S1阶段房室海绵纲的多囊腔海绵属种、叠瓦腔海绵属种和泡腔海绵属种为造礁主体;S2阶段小领针海绵和一纤维海绵未知属种为造礁主体,S3阶段房室海绵的多囊腔海绵占造礁主导地位。统计表明造礁海绵群团的分异度由S1至S3期降低明显。同时着重对本礁点主体的S2阶段骨架礁岩各个部分的结构特征进行细致分析,尤其是RFC的形成历史进行探讨,碳氧同位素测试得到的数据表明S2阶段古水温经历了高达16℃左右的波动,而RFC形成时的古水温为37.86℃,它是一种高温海水的反映;最后通过与南盘江盆地同期的紫云礁和茅口期的广西隆林礁进行对比,揭示它们的成礁模式和演化的异同。     

广西西部二叠纪生物礁中的海绵、水螅动物化石

广西西部田林,凌云、凤山地区二叠纪生物礁的造礁生物－海绵、水螅化石保存完美。文中描述串管海绵7属：Stylothalamia,Lichuanospongia,Tebagathalamia,Imbricatocoelia,Intrasporeocoelia,Rhabdactinia,Lingyunocoelis;纤维海绵3属：Peronidella,Intratubospongia,Cavusonella;水螅1属Radiotrabeculopora以及海托盘类Calathium,其中Lingyunocoelia spherica为新属新种,Lichuanospongia guangxiensis为新种,其它均为中国南方二叠纪生物礁内常见分子。Senowbari-Daryan(1990)提出以Discosiphonella来代替Cystauletes,Ascosymplegma,Lichunospongia3属,但Lichuanospongia的房室形状和中央腔缺失横板（泡沫板）显著不同于Discosiphonella,因此文中仍把Lichuanospongia视作独立属,Lingyuncoelia gen.nov。与Sollasia,Girtyocoelia相似,但房室外壁缺乏任何种类的穿孔,因此明显不同于后两属,作者仍把Radiotrabeculopora视为螅纲内的一属,而没有归于纤维海绵目,因为它最明显的特征是发育分布较规则的放射状支柱（不能视为骨纤构造）,且那些纵向分布的出水管实际上应视为支柱之间的沟道。     

陕西镇巴早寒武世海绵骨针化石

作者对采自陕西省镇巴县下寒武统西蒿坪段和水井沱组下部碳酸盐岩地层的海绵骨针化石进行了研究。三叶虫及小壳化石的生物地层学资料表明西蒿坪段和水井沱组下段属于筇竹寺阶。化石经室内醋酸浸泡处理后获得,骨针化石保存较好、类型多样,其中属于六射海绵纲的骨针3类,普通海绵纲的骨针6类,分类未定的骨针1类(Nabaviellasp.);并详细地对各类骨针化石进行了描述。虽然普通海绵骨针类型多样,但六射海绵的骨针丰度远高于普通海绵。简要地探讨了海绵骨针的保存方式,对比和分析了西蒿坪段和水井沱组海绵骨针化石组成的差异。结合同时代产自皖南荷塘组和云南澄江动物群中特异保存的海绵软躯体化石资料,认为虽然海绵动物起源于新元古代末期,但躯体海绵化石和骨针化石都显示海绵动物的大辐射事件发生在早寒武世筇竹寺期。     

钙质海绵之古生态

古生代生物礁中钙质海绵(纤维海绵、房室海绵、硬海绵)的生态位在中三叠世以后被生态竞争能力更强的六射珊瑚所占据.在古生代和中三叠世的钙质海绵礁上,0-10m深度内钙质海绵很发育.由于与钙藻共生,典型的造礁钙质海绵生活在透光带以内,并且在其上部更丰富.钙质海绵礁也会生长到破浪带内并受风浪的破坏而形成倒骨岩和骨屑岩.对古生代的钙质海绵礁而言,倒骨岩和骨屑岩形成于0-3m水深范围内,亮晶骨架岩形成于3-10m深度范围内,灰泥骨架岩形成于10-20m的水深,障积岩形成于20-30m的水深,潜障积岩形成于30-40m的水深.钙质海绵的生长形态与水深的关系与六射珊瑚与水深的关系一样:细枝状的钙质海绵生长在最浅的水中(相当于礁生长带的上部),在稍深的水中(相当于礁生长带的中部和下部)各种形态的海绵都会出现,在更深的水中可以出现特别大的、锥状的海绵.     

海绵Phakellia fusca Schmidt的化学成分研究(Ⅳ)

用GC-MS法对中国南海扁小轴属海绵Phakellia fusca Schmidt的低极性组分进行了研究,从中分离鉴定出10种羧酸酯及16种链烃化合物。研究对扁小轴属(斧海绵亚目)海绵的化学分类具有一定意义。     

新疆塔里木柯坪地区上奥陶统凯迪阶串管海绵类化石及其滤食选择性探讨北大核心

奥陶纪是串管海绵早期演化的一个关键阶段,记录了该类群的首次大规模辐射演化事件(属级分类单元达15个)。然而,现有大部分奥陶系串管海绵的报道来自澳大利亚东部和北美等地,在中国至今仅发现了两个属,与前述地区相比研究程度偏低。早期研究主要基于形态学特征对串管海绵进行系统分类描述,对其滤食策略知之甚少,因此制约了对此类海绵在奥陶纪底栖生态系统作用的相关探讨。本文系新疆塔里木柯坪地区奥陶纪串管海绵的首次系统古生物学报道,详细描述凯迪阶(上奥陶统)印干组中保存完好的阔室丛花海绵(Corymbospongia amplia)化石的形态学特征,并通过研究标本外壁微孔孔径的大小分布,探讨其滤食选择性。海绵外壁微孔孔径的分析表明:小型和微型浮游生物可能是其食物的主要来源,而多细胞浮游动物因个体尺寸大于海绵外壁微孔,不能被阔室丛花海绵捕获。本研究为奥陶纪串管海绵古生态学及其地球生物学意义的探讨提供了进一步的依据。     

网角海绵目(Dictyoceratida)谱系发育与形态发生分析

采用形态和分子数据相结合的方法探讨网角海绵目谱系发育和骨骼形态发生问题。根据11个普通海绵种的18S rRNA序列,结合11个形态与结构特征以及生化和细胞学性状,对网角海绵目的系统发育关系进行综合分析。分子系统学分析表明,网角海绵目及角骨海绵科为单系类群,具有宽口型领细胞室的掘海绵科属于网角海绵目。表型数据显示,网角海绵目内的4个科(Dysideidae,Thorectidae,Irciniidae,Spongiidae)为单系类群。网角海绵目的单系性表明具有等级分化特征的海绵质骨架纤维为同源特征,而领细胞室类型的分化,即宽口型和二咽型领细胞室的分化,是在网角海绵内部类群分化的同时发生的。结合角海绵类及相关类群的化石记录和文中关于网角海绵谱系发育分析推测,早期网角海绵可能主要通过胶原纤维粘附外源碎屑颗粒来支撑内部骨架系统;网角海绵的演化向两个方向发展:①合成多种海绵质纤维取代外源物形成骨架系统(网角海绵和指角海绵);②合成硅质骨针取代外源颗粒构成海绵骨架(现代所有具有骨针的普通海绵)。     

云南澄江下寒武统细丝海绵化石

前言澄江海绵化石群的系统分类学、生态学、埋藏学和演化生物学等问题将分为不同专题进行研究。本文是关于澄江海绵化石的第一篇报道,研究内容侧重于细丝海绵科系统分类学。细丝海绵科属于普通海绵类,为澄江海绵群体中的优势类型,也是最为原始的普通海绵类之一。它们的骨骼甚薄,主要由席状外骨层所组成。外骨层由大小不相同的两套单轴骨针纵向排列而成;大骨针互相叠接成骨棒状或互相交错排列成网状,以便起着主要的支撑作用。大骨针之     

湖北宜昌乔家坪村寒武系水井沱组海绵动物化石群

海绵动物是最原始的动物门类之一,其演化史对于研究多细胞动物的起源和早期演化至关重要。现有的化石记录显示,水体较深的贫氧环境可能是寒武纪早期海绵动物演化的重要场所之一。前人在贵州、湖南、安徽等多地的斜坡至盆地相黑色页岩中已经报道了数个海绵化石群。在这样的环境中,由于水动力作用较弱,海绵骨架结构容易得到原位保存。湖北宜昌秭归乔家坪村剖面的水井沱组为一套寒武系第三阶的台内凹陷沉积。本文描述在此剖面顶部发现的一个海绵动物化石群,其中包含Palaeosaccus minus sp.nov.、Triticispongia giganta sp.nov.、Triticispongia cf.diagonata、Sanshapentella dapingi、?Wapkia sp.以及三类分类未定的海绵动物化石,共8类,分属至少4个属。其中Triticispongia和Sanshapentella也常见于前人报道的多个同时期深水相海绵动物化石群。除此以外,作者还识别出了三种根束类型。水井沱组海绵动物化石群所呈现出的形态多样性进一步佐证了在寒武纪大爆发期间,至515 Ma左右,海绵动物已成功适应多种环境,且繁盛于水体较深、大多数动物难以生存的贫氧环境。     

Uranium in scleractinian coral skeletons

Accurate determinations have been made of the distribution of uranium in fresh and diagenetically altered coral skeletons occurring both naturally and grown under a variety of experimental conditions. Whereas live coral skeletons are homogeneous in uranium distribution, dead skeletons show heterogeneities relating to lithothamnioid algal encrustations and endolithic sponges. In the analyses of over 100 live coral skeletons, no zonal uranium distributions, described by previous workers, were found. In skeletons, free from organic material, uranium was found to exchange readily with the coral skeleton and/or to be precipitated along trabecular axes and skeletal margins. Bioeroded specimens contained higher uranium concentrations than freshly formed aragonite; they were similar to fossil coral skeletons used by previous researchers for uranium scrics dating.     

Skeletal development in Hermesinum adriaticum Zacharias, a flagellate from the Salton Sea, California

Hermesinum adriaticum is a rarely reported unicellular biflagellated organism with a solid siliceous skeleton. Live specimens were not observed but many skeletons were found in sediments and, in small numbers, in cyanobacterial mats and the water column of the Salton Sea, a salt lake in California, U.S.A. Stages of the developing skeleton were studied with scanning electron microscopy, and the progression from small tetraxial daughter skeletons to complete asymmetrical adult skeletons is presented. Some variability in the adult skeletons is illustrated.     

Conformation and elasticity of the isolated red blood cell membrane skeleton.

We studied the structure and elasticity of membrane skeletons from human red blood cells (RBCs) during and after extraction of RBC ghosts with nonionic detergent. Optical tweezers were used to suspend individual cells inside a flow chamber, away from all surfaces; this procedure allowed complete exchange of medium while the low-contrast protein network of the skeleton was observed by high resolution, video-enhanced differential interference-contrast (DIC) microscopy. Immediately following extraction in a 5 mM salt buffer, skeletons assumed expanded, nearly spherical shapes that were uncorrelated with the shapes of their parent RBCs. Judging by the extent of thermal undulations and by their deformability in small flow fields, the bending rigidity of skeletons was markedly lower than that of either RBCs or ghosts. No further changes were apparent in skeletons maintained in this buffer for up to 40 min at low temperatures (T less than 10 degrees C), but skeletons shrank when the ionic strength of the buffer was increased. When the salt concentration was raised to 1.5 M, shrinkage remained reversible for approximately 1 min but thereafter became irreversible. When maintained in 1.5 M salt buffer for longer periods, skeletons continued to shrink, lost flexibility, and assumed irregular shapes: this rigidification was irreversible. At this stage, skeletons closely resembled those isolated in standard bulk preparations. We propose that the transformation to the rigid, irreversibly shrunken state is a consequence of spectrin dimer-dimer reconnections and that these structural rearrangements are thermally activated. We also measured the salt-dependent size of fresh and bulk extracted skeletons. Our measurements suggest that, in situ, the spectrin tethers are flexible, with a persistence length of approximately 10 nm at 150 mM salt.     

Formation of the skeletal system of white rat and golden hamster embryos during experimental hypovitaminosis B1

In pregnant females B1-hypovitaminosis was induced by injecting various doses of oxythiamine--a specific antimetabolite for B1 vitamin. The rat and hamster embryos were respectively treated on the 20th and 15th days of development after the technique suggested by Dauson-Dyban with staining the osseous anlages of the skeletons with alizarine red. The results of the investigations performed in 193 skeletons of the rat embryos and in 196 skeletons of the golden hamster embryos revealed a progressive decrease, as the dose of oxythiamine increased, in length of ossification anlages of the extremity bones. However, susceptibility to lesions in various bones of the extremity and skull skeletons was not similar under conditions of progressive oxythiamine-induced B1-hypovitaminosis and depended on time of their anlage formations.     

Microscopy electron scanning of fossilized sickle-cells

In a microscopica electronic scanning follow-up study on human skeletons from the Hellenistic Period in the Arab-Persian Gulf, fossilized sickle-cells were found in the bone marrow of one of the excavated skeletons. The ultrastructure of these cells was compared to that of fossilized normal red blood cells of other skeletons from the same site, and to similar pseudo-pathological structures. The finding of fossilized evidence of sickle-cell anemia of that date is withoutprecedent, and makes an evaluation of related gross-anatomical skeletal changes possible.     

Soluble organic matrices of aragonitic skeletons of Merulinidae (Cnidaria, Anthozoa)

Our interpretation of the overall taxonomy and evolution of the Scleractinia, the most important reef builders in tropical areas, has long depended exclusively on morphology of the calcareous skeletons. The reported series of physical and biochemical characterizations of skeletons and the mineralizing matrices extracted from the skeletons allow, for the first time, the level of biochemical diversity among corallites of the same family to be estimated. Similarities and differences observed in the micro- and nanostructures of the skeletons reflect those of the soluble organic matrices. Sulphur is mainly associated with sulphated acidic sugars. The role of sulphated sugars on the biomineralization processes is still underestimated. The resulting data suggest that environmental conditions may act on the mineralization process through the detailed compositions of the mineralizing matrices.     

Occurrence and diversity of lipids in modern coral skeletons

Coral skeletons are composite acellular structures, in which organic macromolecules are intimately associated with mineral phases. Previous studies focussed on proteins and sugars of the soluble organic matrices extracted from the skeletons. Here we report the occurrence of diverse lipids which were extracted from the aragonitic skeletons of seven modern coral species. Using thin layer chromatography, we show that these lipids differ in quantity and composition between the species. Higher proportions of sterols and sterol esters in skeleton extracts as compared to a much higher abundance of waxes and triglycerides in previously studied extracts from scleractinian soft tissues suggest a specific, although not yet determined, role in biomineralisation. The occurrence of intraskeletal lipids along with other organic components should also be taken into account when using coral skeletons as bone allografts, as well as in fossilisation processes.     

Results of computer-assisted studies of population structure and burial practices of adults of the late Roman burial ground in the Minshat Abu Omar (east Nile delta)]

The results of 1448 skeletons met the requirements (database) for the completed examinations. Statistical correlations between situation of the skeletons in view of compass directions, position of the skeletons, grave type and mumification traces were calculated. More than 90% of the analyzed individuals were buried in west-east direction (head-feet). In 69% of all cases the skeletons were buried with their hands on or next to the pelvis. 98% of all mummies examined were found in the position hand/hands on shoulder. Special grave architecture was given in 15.8% of the examined individuals. The average life-expectancy for the group between 20 to 29 amounted to 14.65 years. The cluster-analysis showed clear differentiation of the male group in 3 to 4 subpopulations. For the female group a mathematical probability for 3 subpopulations was given. Connecting the data of cluster and burial types a significant distinction between the four male clusters - according to the distribution of the skeleton positions - could be seen. Within the female group a clear correlation between clusters and common characteristics could be found in 7 subgroups. Differentiated distribution was revealed in the different alignments of the skeletons.     

A new aid to aging immature skeletons: development of the occipital bone

A total of 150 immature and young adult skeletons from the medieval necropolis at Mistihalj, in southern Yugoslavia, were aged by the standard methods: dentition, osseous development, and extent of vertebral union. The development of the occipital bone was examined in 117 cases to determine if it could be used in aging the skeletons. The stages of development were found to be regular enough to permit reasonable prediction of age for other Yugoslavian specimens. Comparisons with a series of 20 German fetuses suggest measurements of the parts of the occipital bone can be used to help determine the approximate age of skeletons in the fetal to few-months post-natal range. Comparisons with the ten Egyptian skulls and data on 19 unpublished Eskimo skeletons suggest that the stages of development can be used with other populations.     

Microboring organisms in living stylasterid corals (Cnidaria,Hydrozoa)

Microboring or euendolithic microorganisms, which colonize and penetrate various carbonate substrates, are abundant in coral reef ecosystems and play a major role in reef carbonate dissolution. A few studies reported the presence of euendoliths in stylasterid coral skeletons but the biological identity, distribution and abundance of these microorganisms remain largely unknown. Observations of over 100 stylasterid colonies, collected in the Indo-Pacific area, revealed for the first time that the association between these corals and euendolith organisms appears to be quite common in shallow tropical waters. The most abundant euendolith was identified as a cryptic stage in the development of the rhodophyte Porphyra (Conchocelis stage). The euendoliths were observed in the skeletons of seven species of three genera (four Stylaster, two Distichopora and one Lepidotheca). The presence of euendoliths inside skeletons conferred a particular colour to the studied stylasterid corals. Distribution and abundance of microborings varied significantly among stylasterid species and among branches of a single colony and so did the colour of their skeletons. Colonization of skeletons and the associated colour distribution were almost uniform in some stylasterids, forming an upward gradually diminishing or sharply limited gradient. This study shows that patterns of euendolith colonization and growth in stylasterid skeletons may depend on the stage of the euendolith development as well as on their environmental requirements such as light exposure.