共栖于对虾体表的致病性纤毛虫Ⅱ.(纤毛动物门,缘毛目)

作为系列报道的第二部分记述了黄渤海区共栖于对虾体表的3属15种缘毛类纤毛虫,其中包括8种国内新记录及聚缩虫属的一新种——拟钩虾聚缩虫。文中对所涉种类的形态学特征做了概括性描述及图示,以期为对虾养殖中病原的调查鉴定及进一步的动物区系研究提供一基础资料。     

The distribution and morphology of tintinnids (ciliate protozoans) from the coastal waters around New Zealand

Tintinnids from the surface plankton of New Zealand coastal waters are illustrated with scanning electron micrographs. Brief notes are given on their taxonomy, and their use of silica grains, diatom valves, and coccoliths in construction of the lorica is discussed. Distributional data are given for each species and these are related to the hydrological regime.     

原生动物单细胞PCR应用初探——以天蓝喇叭虫为例

以天蓝喇叭虫(Stentor coeruleus)为研究对象,探索了单细胞单基因PCR扩增及单细胞全基因组PCR扩增技术在原生动物中的应用.经过不断探索和优化条件后,试验取得了理想的结果.在40例单细胞单基因(SSU rDNA基因全序列)PCR的一次性扩增中,新鲜细胞和经过中性红染色的细胞都获得了100%的成功率,室温下酒精(95%)保存一周的细胞获得了82.5%的成功率.在单细胞全基因组PCR扩增中,采用高效高保真的phi29 DNA聚合酶结合随机引物(Random Primer)进行扩增,获得了丰富且质量较高的PCR产物.以全基因组扩增产物(稀释10倍)对四个常用的基因位点(TEF1、SSU rRNA、18S-ITS1-5.8S、a-tubulin)进行扩增,均成功获得相应的基因片断.     

Juvenile form of the New Zealand turbot Colistium nudipinnis (Waite) (Pisces: Heterosomata: Rhombosoleinae) (note)

A juvenile (26 mm) specimen of the New Zealand turbot Colistium nudipinnis (Waite) is figured and described. Differences between the juvenile and adult forms, and characters distinguishing juvenile C. nudipinnis from the young of other New Zealand species of flatfish, are noted.     

Vase-shaped microfossils from the Ediacaran Weng'an biota, Guizhou, South China

Vase-shaped microfossils (VSMs) are described from the Ediacaran Doushantuo phosphorites (ca. 599–584 Ma) of Guizhou Province, South China. They are morphologically attributed to two genera and three species, and thus expand our knowledge of the Neoproterozoic protozoans in the Weng'an biota. They resemble to the VSMs from the Lower Cambrian pre-trilobitic Kuanchuanpu Formation of southern Shaanxi Province in terms of the microstructures and chemical composition of the fossil walls. Microscopic observations indicate that the VSMs from both the Weng'an biota and the Kuanchuanpu Formation are preserved in either single-layered or multi-layered walls, and composed of calcium phosphate in chemical composition. The present fossils also share similarities, in size and general contour, to the VSMs previously described from the Gaojiashan Member, middle part of the Dengying Formation (ca. 551–542 Ma) in southern Shaanxi. The discovery of the VSMs from the Doushantuo phosphorite is an important contribution to the Weng'an biota, and may throw much light on the early evolution and diversification of protozoans during Precambrian–Cambrian interval.     

Cellular iron contents of plankton during the Southern Ocean Iron Experiment (SOFeX)

Iron (Fe) availability limits phytoplankton biomass and production in large regions of the Southern Ocean and influences community composition and size structure, which may affect C export and other system-level functions. To improve our understanding of Fe partitioning within communities and the response of different components to fertilization, we assessed the cellular Fe contents of individual diatoms, autotrophic flagellates, and heterotrophic flagellates during the recent Southern Ocean Fe Experiment using synchrotron-based X-ray fluorescence (SXRF). Dual ⁵⁵Fe/¹⁴C radioisotope incubations were also conducted to estimate Fe:C ratios in size-fractionated plankton. Cellular Fe quotas determined by the two techniques were in close agreement when low amounts of ⁵⁵Fe (0.2 nM) were added, but ⁵⁵Fe additions of 2 nM resulted in 2–3-fold higher quotas. SXRF assessments of cellular Fe quotas (normalized to C) were generally in good agreement with prior bulk analyses of natural assemblages, but revealed compositional differences among protistan taxa not previously detected. Mean Fe:C ratios for diatoms, autotrophic flagellates, and heterotrophic flagellates from unfertilized waters were 6.0, 8.7, and 14.1 μmol mol C⁻¹, respectively. Smaller cells had higher Fe:C ratios than larger cells. Fertilization enhanced Fe quotas in all cell types, with mean Fe:C ratios increasing approximately 4-fold (from about 10 to about 40 μmol mol C⁻¹) after two Fe additions. This study provides some of the first measurements of Fe quotas in phytoplankton cells from natural communities and the first measurements of Fe quotas in natural protozoa.     

共栖于对虾体表的致病性纤毛虫Ⅲ.(纤毛动物门,缘毛目)

本文为系列报道的第三部分,记述了黄渤海区共栖于对虾体表的5属12种缘毛类纤毛虫,包括一新种,一新亚种(上村累枝虫,海洋透明鞘居虫)及7种国内新记录。文中描述了诸种的形态学特征并列表给出了其主要分类性状的统计学资料。     

Effects of periodic addition of lead on a marine protistan community

Marine protist communities developed in laboratory microecosystems have been used to study lead tolerance and toxicity. Lead was added at periodic intervals during 240 h. 1 mg · 1^–1 was the concentration tested. The lead caused a decrease of the total number of protist species, a phenomenon reflected in the diversity values. The general trophic structure remained unchanged. Bacterivores and photoautotrophs were the most abundant trophic groups in the control. 48 h after the addition of the toxic solution, a significant reduction in the number of photoautotrophs was observed. Bacterivores were affected until 96 h. The protist biomass values showed a 60% reduction. There were species presented only to the control and others found only in the lead treatment. The effects caused by the lead could be explained by the characteristics of the physico-chemical parameters, which reduced the toxicity of the metal.     

Ingestion of bacteria in a eutrophic subtropical reservoir pond with food web mainly controlled by zooplankton grazing

This study evaluated the zooplanktonic bacterivory at a eutrophic subtropical reservoir pond by the quantification of the bacterial grazing and clearance rates of the protozooplanktonic (ciliates and nanoplankton) and metazooplanktonic (rotifers, cladocerans and copepods) populations during one year period. For this purpose, in situ experiments with fluorescently labeled bacteria (FLB) were carried out every two months on the sub-surface of the reservoir pond. Considering the individual grazing and clearance rates, the metazooplanktonic organisms showed the highest consumption of bacteria. However, in terms of population and considering all the zooplanktonic community, the heterotrophic nanoplanktonic organisms (HNP) accounted for 73% of the total bacteria ingested, being the most important bacterial consumers in the reservoir, due to their high population densities. Among them, the HNP smaller than 5 μm showed the highest population grazing rates, also due to their high abundance. These organisms were the main responsible for bacteria regulation by grazing in the reservoir. Among the metazooplanktonic organisms, the highest ingestion of bacteria occurred by the copepods (10%) during the wet season, and by the rotifers (22%) during the dry season. Thus, the metazooplanktonic population grazing rates were significantly different over the year, between the cold/dry and hot/rainy season. These seasonal differences were not observed in the density and biomass of picoplankton nor in the population grazing rates of ciliates and HNP. Nevertheless, the protozoa (ciliates and HNP) were directly responsible for most of the predation on bacteria, while the metazooplanktonic populations were indirectly responsible for it by the consumption of protozoa in a cascading effect.     

Hazard evaluation of lead effects using marine protozoan communities

Protozoan communities developed in laboratory microecosystems were used to evaluate the toxic effects of lead ion. The lead was added as lead acetate in different concentrations (50 g · l^–1, 20 g · l^–1, 10 g · l^–1 and 1 g · l^–1). The protozoans were taxonomically identified and classified into functional groups according to their common nutritional type. The population dynamics of protozoa has been studied. In the control the most frequent groups were bacterivore-detritivores and photosynthetics (more than 75% of abundance). Noticeable lead effects were observed after 24 hours of exposure to metal in all fractions. In general, the lead caused reductions in the number taxa, in total protozoan abundance and in protozoan biomass. The diversity values decreased in more than two nep respect to control in the different fractions. At the end of assay, the protozoan communities structure was simplified in the fractions with lead and some species of little flagellates were dominant. The information provided by this microecosystems of protozoan community was more complex than the one provided by single-species bioassays. Community protozoan bioassays may give more information about the toxic effects to compare with actual ecosystems.