贵州清镇早寒武世早期藻类化石

从贵州清镇阿坝寨震旦系一寒武系界线剖面,寒武系底界附近的燧石岩石薄片中,发现的一种保存很好的藻类化石——一种内部具浓密胶状物质的多细胞球形群体化石。它不同于以往在前寒武纪发现的所有藻类化石,故建新属 Symphysosph(?)era gen.nov.(属型种 Symphy-sosphaera radiaalis gen.et sp.nov.)。文中详细比较了新属和几个已知属的区别及可能的亲缘关系。     

Variations in the dispersal curves of macroalgal propagules from a source

The process of dispersal is critical to marine benthic species (i.e. invertebrates and algae) as a fundamental element of population ecology and a crucial ecological process that maintains the diversity in communities. We simultaneously sampled the abundance of spores inhabiting the water column at different distances from known parent sources at 3 sites along the coast of central Chile. From these data we constructed 258 dispersal curves for common rocky intertidal macroalgae. Only 43.8% of these curves could be predicted by the expected model, which describes the spatial distribution of propagules to be dominated by a larger concentration near the parent individual or “source site”, followed by a marked decrease in abundance with increasing distance. The curves that departed from the expected model (56.2%) were grouped into three curve types, according to the number of propagule abundance maxima observed in space. This work suggests that macroalgal propagule dispersal patterns are more variable than previously thought. The existence of several alternative curves to the expected model, as well as the presence of one to several abundance maxima associated with the differential distribution of propagule patches in the water column, suggests the idea that propagules are released in pulses which can be transported variable distances from the source site.     

三峡水库蓄水前后水生态系统动态的初步研究

本专辑登录的论文系中国科学院知识创新工程重要方向性项目“三峡水库库区蓄水前后水生态系统变化的研究”的部分研究结果,内容包括1)蓄水前后水体理化参数变化;2)蓄水前后水生生物群落变化;3)三峡水库的富营养化问题;4)春季水华暴发过程的连续监测与动力学;5)对三峡水库生态学研究的几点思考和建议。       

Coralline red algal limestones of the late Eocene alpine Foreland Basin in Upper Austria: Component analysis, facies and palecology

Summary Late Eocene sediments of the Upper Austrian Alpine Foreland Basin discordantly overlie Mesozoic and crystalline rocks, which are deeply eroded and form a distinct pre-Eocene relief. Late Eocene deposits contain red algal limestones with a remarkable lateral extent and a high diversity of sedimentary facies. Towards the south the algal limestones change into more clastic sediments, which are characterized by larger foraminifera and bryozoans. Main components are coralline algal branches and detritus, coralline crusts, rhodoliths, peyssonneliacean aggregates and crusts, nummulitid and orthophragminid foraminifera, corals, bryozoans, as well as terrigenous components. Rank correlation and factor analysis were calculated in order to obtain informations about relations between components. Hierarchical cluster analysis allowed the designation of 17 facies, most of them are dominated by coralline algae. Actualistic comparisons and correlations obtained from statistical analyses allowed the reconstruction of the depositional environments. Main features of the northern area are huge accumulations of unattached coralline algae (branches, rhodoliths, detritus), which are comparable to the present-day “Maerl”-facies. They formed loose frameworks cut by sand channels. The frequency of coralline detritus decreases upsection. Peyssonneliacean algae in higher parts of the profiles show growth-forms that are comparable to peyssonneliaceans of the Mediterranean circalittoral soft bottoms. This succession can be interpreted by an increasing relative sea level. Besides, crustose coralline algal frameworks were growing on morphological highs which are partially comparable to the present-day “Coralligéne de Plateau” of the Mediterranean Sea. In contrast to the northern area, sedimentation rate of the southern area is too low to keep up with rising sea level. The typical succession from nummulitid- to orthophragminid-and bryozoan-dominated facies can be interpreted by an increasing water depth from shallowest subtidal to the deeper photic zone and finally to the aphotic zone.     

The occurrence of potentially toxic dinoflagellates and diatoms in a subtropical lagoon, the Indian River Lagoon, Florida, USA

The occurrence of potentially toxic phytoplankton species was examined over a 5-year period in a region of the Indian River Lagoon in Florida that has recently been subject to ecologically significant events, putatively related to algal toxins. The results of the study reveal a significant presence of two species of phytoplankton that have been shown to be toxic in Florida or other regions of world, the dinoflagellate Pyrodinium bahamense var. bahamense and the diatom Pseudo-nitzschia pseudodelicatissima. Concentrations of the former species reached 638,000 cells l⁻¹ and concentrations of the latter reached 23.9 million cells l⁻¹. In addition, the abundance of one of these species, P. bahamense var. bahamense appears to have increased over the 5-year study period from 1997 to 2002. It may be hypothesized that rainfall events following a regional drought period resulted in a flushing of bioavailable phosphorus and nitrogen into the Indian River Lagoon that stimulated P. bahamense var. bahamense blooms. The significance of these results is discussed within the context of the ecology of this flow-restricted lagoon.     

产毒微囊藻藻粉的脱毒技术研究

为了达到对收获的微囊藻藻粉安全脱毒的目的 ,分别使用了调节pH ,NaClO处理和臭氧处理微囊藻干粉 ,并检测其脱毒效果和脱毒过程中蛋白质的损失率 ,以期找到一种可行的微囊藻藻粉安全脱毒方法。研究结果表明 ,调节pH值的方法试剂用量大且脱毒不彻底 ;NaClO处理也因对藻粉的渗透性较差而效果不佳。臭氧水溶液处理藻粉 ,处理时间短 ,且脱毒彻底 ,有实际应用前景     

光合率作为藻类毒理测试指标

以氧电极法的光合率作为藻类毒性测试指标。整个测试过程准确,简便,快速。能够随时测定受试毒物对藻类光合作用的效应,与常规毒性试验比较,测定时间由96h缩短到2h。灵敏度约提高了一倍,Cu~(2 )对光合作用的半数效应浓度(EC_(50))是0.105mg/L,比Cu~(2 )对藻的急性毒性试验的EC_(50)(0.204mg/L)少了一倍。     

Lipid and fatty acid composition of the green oleaginous alga Parietochloris incisa,the richest plant source of arachidonic acid

We have hypothesized that among algae of alpine environment there could be strains particularly rich in long chain polyunsaturated fatty acids (LC-PUFA). Indeed, the chlorophyte (Trebuxiophyceae) Parietochloris incisa isolated from Mt. Tateyama, Japan, was found to be the richest plant source of the pharmaceutically valuable LC-PUFA, arachidonic acid (AA, 20:4omega6). The alga is also extremely rich in triacylglycerols (TAG), which reaches 43% (of total fatty acids) in the logarithmic phase and up to 77% in the stationary phase. In contrast to most algae whose TAG are made of mainly saturated and monounsaturated fatty acids, TAG of P. incisa are the major lipid class where AA is deposited, reaching up to 47% in the stationary phase. Except for the presence of AA, the PUFA composition of the chloroplastic lipids resembled that of green algae, consisting predominantly of C(16) and C(18) PUFAs. The composition of the extrachloroplastic lipids is rare, including phosphatidylcholine (PC), phosphatidylethanolamine (PE) as well as diacylglyceryltrimethylhomoserine (DGTS). PC and PE are particularly rich in AA and are also the major depots of the presumed precursors of AA, l8:3omega6 and 20:3omega6, respectively.     

Ultrastructural responses in field-bleached and experimentally stressed Amphistegina gibbosa (Class Foraminifera)

Amphistegina are the most common foraminifers with algal endosymbionts found on reefs and carbonate shelves worldwide. Like zooxanthellate corals and other reef organisms with algal symbionts, Amphistegina respond to photoxidative stress by bleaching. This paper documents ultrastructural changes that occur during bleaching under field and laboratory conditions. Nine chambers from the outer whorl of each of 22 normal-appearing and 11 partly bleached specimens of Amphistegina gibbosa, which were collected from Conch Reef, Florida, USA, were examined using transmission electron microscopy. The condition and numbers of algal symbionts, as well as the cell area occupied by 10 other intracellular structures of the host, were quantified. Normal-appearing specimens averaged three times more viable symbionts and less than a fourth as many deteriorating symbionts as partly bleached specimens. Foraminifers experimentally exposed to visible light intensities > or = 13 micromole photon m(-2) s(-1) for 35 d were statistically similar to partly bleached field specimens in the number and condition of symbionts, and in chamber area occupied by the evaluated host structures. Exposure to 32 degrees C water temperature at 6-8 micromole photon m(-2) s(-1) for 28 d induced symbiont loss but did not degrade host endoplasm.     

Flow cytometric studies of the host-regulated cell cycle in algae symbiotic with green paramecium

Summary. Paramecium bursaria (green paramecium) possesses endosymbiotically growing chlorella-like green algae. An aposymbiotic cell line of P. bursaria (MBw-1) was prepared from the green MB-1 strain with the herbicide paraquat. The SA-2 clone of symbiotic algae was employed to reinfect MBw-1 cells and thus a regreened cell line (MBr-1) was obtained. The regreened paramecia were used to study the impact of the hosts growth status on the life cycle of the symbiotic algae. Firstly, the relationship between the timing of algal propagation and the host cell division was investigated by counting the algal cells in single host cells during and after the host cell division and also in the stationary phase. Secondly, the changes in the endogenous chlorophyll level, DNA content, and cell size in the symbiotic algae were monitored by flow cytometry and fluorescence microscopy. The number of algae was shown to be doubled prior to or during the host cell division and the algal population in the two daughter cells is maintained at constant level until the host cell cycle reenters the cytokinesis, suggesting that algal propagation and cell cycle are dependent on the hosts cell cycle. During the hosts stationary growth, unicellular algal vegetatives with low chlorophyll content were dominant. In contrast, complexes of algal cells called sporangia (containing 1–4 autospores) were present in the logarithmically growing hosts, indicating that algal cell division leading to the formation of sporangia with multiple autospores is active in the dividing paramecia.Correspondence and reprints: Graduate School of Environmental Engineering, University of Kitakyushu, 1-1 Hibikino, Wakamatsu-ku, 808-0135 Kitakyushu, Japan.