异毛虫形成包囊过程中细胞皮层及纤毛结构分化的扫描电镜观察

在纤毛虫无性生殖中,生命活动受阻时经常会发生形成包囊的现象。研究纤毛虫的包囊现象,已成为揭示真核细胞的结构与功能、细胞模式形成与控制机理的一个重要方面。目前,对腹毛目纤毛虫中游仆虫类包囊的形态及其生理生化特征已进行了较系统的研究,积累了较多的资料,但对其他类     

海洋浮游纤毛虫生长率研究进展

浮游纤毛虫是海洋环境中连接微食物网与经典食物链的重要中介,在浮游生态系统的物质循环和能量流动中发挥着重要的作用。从20世纪70年代末开始,国际上已在实验室内和海上现场开展了对浮游纤毛虫生长率的研究;国内在这方面起步比较晚,只有在实验室内对浮游纤毛虫生长率进行过少量研究,海上现场生长率的研究迄今尚无。对相关浮游纤毛虫生长率的研究成果进行了综述,以期为我国的相关研究提供借鉴。室内培养的研究结果表明,浮游纤毛虫的生长率与温度和饵料有关,在特定的温度下,饵料浓度低于生长阈值浓度时,纤毛虫停止生长,随饵料浓度的上升,生长率增加,饵料浓度增加到一定程度,生长率达到内禀生长率,此后,随饵料浓度增加不再增加。目前在实验室内测定了34种海洋浮游纤毛虫的内禀生长率,范围为0.1—3.05 d-1。在特定的饵料种类下,纤毛虫的内禀生长率与温度有关,温度过低停止生长甚至死亡,在此基础上,随温度升高,内禀生长率呈线性增加,温度增加到一定程度,内禀生长率降低。pH值升高对纤毛虫的生长有不利影响。估计自然海区纤毛虫生长率的方法主要是海水分粒级培养法,得出的生长率最大为3.3 d-1。自然海区的纤毛虫生长率受温度影响较大,缺氧区纤毛虫生长率的变化因纤毛虫类群而不同,纤毛虫生长是否受饵料影响(上行控制)在不同的海区有不同的结果。根据纤毛虫生物量和生长率可以估计纤毛虫生产力,大多数纤毛虫生产力的估计高于桡足类生产力。     

纤毛虫形成包囊和脱包囊的研究及其意义

原生动物纤毛虫的生活史中,经常涉及到无性生殖或有性生殖过程,这是众所周知的。而除此之外,许多纤毛虫生命活动受到阻碍时,又往往发生形成包囊(encystment)的过程。此封,纤毛虫由活动状态变为静止不动,在细胞团缩并逐渐失去某些结构的同时,分泌物质形成包囊壁(cyst wall),成为圆球形或近圆球形的包囊(cyst)。一旦环境适宜,形成包囊的细胞则会脱包囊(xcystment),恢复正常的活动。     

营养期和休眠期冠突伪尾柱虫的类中间纤维-核纤层-核骨架体系

近年来的研究表明 ,尽管不同类群的纤毛虫形成包囊过程中 ,细胞经历了不同程度的分化 ,形成不同类型的包囊 ,但是其休眠包囊生命活动中对细胞内物质的消化、能量利用和代谢等都具有共同的特征 (顾福康等 ,1995 ,1999;李恭楚等 ,1999;陈灵等 ,2 0 0 0 )。这一现象提示 ,纤毛虫在休眠条件下的生命活动可能具有一些相同的物质和结构基础。由于在高等真核细胞中普遍存在的中间纤维-核纤层 -核骨架体系对细胞生命活动起到多方面的重要作用 ,并且尽管目前仅对极少数原生动物观察到该结构体系 ,但它却预示了在这一原始的单细胞类群中以中间纤维为基…     

海洋浮游纤毛虫在世界海区的时空分布

作为微型浮游动物的重要组成部分,海洋浮游纤毛虫是连接微食物环和经典食物链的重要中介,在海洋浮游生态系统物质循环和能量流动中发挥重要的作用.从20世纪60年代至今,关于纤毛虫丰度和生物量的分布已经积累了大量的资料,目前纤毛虫丰度和生物量分布的研究大部分集中在温带海区,热带和极地海区的研究尚少.本文概述了世界海区纤毛虫丰度和生物量的水平分布、垂直分布特点及周年变化规律.纤毛虫丰度和生物量一般在饵料丰富、生产力较高的海区较高;纤毛虫倾向分布在水体的中上层;纤毛虫的丰度和生物量一年之内呈现双峰型或单峰型,纤毛虫群落的粒级组成一般春季较大,夏季较小,砂壳纤毛虫丰度占纤毛虫丰度的比例一般在夏季或秋季较高.     

汕头南澳海域不同养殖区浮游纤毛虫群落结构的比较

为比较不同海水养殖模式对纤毛虫原生动物群落结构和水环境的影响,于2014年4—6月,对汕头南澳海域鱼类养殖区、贝类养殖区、大型海藻龙须菜栽培区和自然水体(对照海区)的纤毛虫和主要水质指标进行了每3~4 d一次的高频次监测,并应用沉积物捕捉器研究了纤毛虫包囊的沉降通量。结果表明:调查区域共发现纤毛虫17种,纤毛虫丰度为75~150 ind·L-1,对照海区和鱼类养殖区内纤毛虫丰度变化相对剧烈;龙须菜栽培区纤毛虫功能群中食藻者所占比例达50%;鱼类养殖区纤毛虫包囊沉降通量最高,平均沉降1.9×104cysts·d-1·m-2,显著高于对照海区和龙须菜栽培区;不同养殖区水体纤毛虫群落结构与沉积物中包囊群落结构有较大差异,龙须菜栽培区纤毛虫群落结构最稳定。     

2010年两个航次獐子岛海域浮游纤毛虫丰度和生物量

2010年7、8月在北黄海獐子岛海域进行了浮游纤毛虫丰度和生物量的调查。7月浮游纤毛虫的平均丰度为(5107±4451) 个/L,平均生物量为(10.17±9.06) μg C/L。8月浮游纤毛虫的平均丰度为(7894±7212) 个/L,平均生物量为(15.24±18.49) μg C/L。7月表层浮游纤毛虫丰度和生物量均呈现近岸多、远岸少的趋势。8月Y1-3、Y2-5两个站表层纤毛虫丰度较高,Y2-5、Y1-1两个站表层纤毛虫生物量较高。7月STA断面浮游纤毛虫丰度呈现表层或次表层高、底层低的特点。8月STA、Y1断面纤毛虫丰度在表层或次表层高、底层低,而Y2断面纤毛虫垂直分布较一致。7月纤毛虫水体丰度及生物量在近岸较远岸高, 8月纤毛虫水体丰度及生物量在离岛较近的Y2-5、Y1-1两站较高。7、8月航次中分别鉴定出砂壳纤毛虫17和21种,其中拟铃虫属(Tintinnopsis)种数最多,Tintinnopsis corniger Hada, 1964为中国海区的新记录种。7、8月砂壳纤毛虫丰度占纤毛虫总丰度的平均比例分别为(19.0±21.6)%和(13.0±16.1)%;7、8月砂壳纤毛虫生物量占纤毛虫总生物量的平均比例分别为(58.2±33.0)%和(42.6±33.2)%。7、8月两个航次中小型无壳纤毛虫在无壳纤毛虫丰度中均占绝对优势。     

休眠期和营养期包囊游仆虫的纤毛器骨架及其微管蛋白

应用光镜和透射电镜术 ,显示了包囊游仆虫休眠细胞中纤毛器骨架的形态 ,并对该纤毛虫休眠细胞和营养细胞的纤毛器及其α、β -微管蛋白进行了免疫荧光定位的比较研究。由免疫荧光显微术显示 ,包囊游仆虫形成休眠包囊后 ,背部毛基体完整地按原有模式保存下来 ;纤毛杆解聚后微管蛋白多集中在细胞皮层 ,小部分均匀散布在细胞质中。据所得结果认为 ,包囊游仆虫形成包囊后 ,微管蛋白主要有 3个去向 ,即 :①处于自噬泡内被逐步消化 ;②以“微管蛋白库”的形式分布于细胞皮层及细胞质中 ;③保留在残留的基体中。此外 ,以往研究中发现的棘毛基部纤维网络未被标记上 ,提示这些纤维体系可能不属于微管系统     

凡纳对虾淡化养殖池浮游纤毛虫研究

在对虾养殖环境,纤毛虫能摄食大量的腐质和藻类,促进对虾养殖水体的自身净化;但缘毛类 Peritrichida 和吸管虫类Suctorida纤毛虫能大量固着生活在对虾的附肢、鳃等部位,是对虾养殖的重要危害生物。在我国,对海水、盐碱池和淡水养殖环境的浮游动物(包括纤毛虫)有较多的研究,对河口区斑节对虾淡化养殖环境浮游生物也有报道,本文报道了珠海市斗门区某凡纳对虾 Litopenaeus vannamei(南美白对虾)养殖基地44口淡化养殖虾池浮游纤毛虫种类及数量组成, 并对其中 1-5号虾池养殖过程中的纤毛虫种群的动态变化进行了研究,以期为凡纳对虾淡化养殖提供参考。       

我国浮游动物学三十年来的回顾与前瞻(1934—1964)

解放前,我国浮游动物学基本上是一门空白学科,仅仅在分类方面进行了一些零星、分散的研究。和其他生物学科一样,它的蓬勃发展是在解放后才开始的。在解放后的短短十多年中,不但在分类研究方面作出了巨大成绩,并且更重要的是,在生态研究方面也获得了显著的进展。从研究趋势看来,今后浮游动物学的研究,将朝着生态、生理、生化的实验科学方向大力发展。过去成就我国浮游动物学的发展过程,大致可分为解放前和解放后两个阶段。在解放前的漫长岁月中,仅在原生动物、水母类、轮虫类、甲壳动物和毛颚动物方面作过一些零星的分类研究,其中以原生动物(主要是腰鞭毛虫类和沙壳纤毛虫类)的分类研究较为突出。至于生态研究几乎完全空白,仅在季节分布方面作过初步观察。由此可见,解放前的浮游动物学研究几乎全是     

两种纤毛虫营养细胞和休眠细胞蛋白组成的比较分析

应用生化抽提和SDS-PAGE方法显示,膜状急纤虫(Tachysoma pellionella)的营养细胞含38条蛋白谱带,休眠细胞含29条蛋白谱带,两者共有谱带为26条,特有谱带各为12条和3条,相似度为77.6%;休眠细胞的包囊壁含22条蛋白谱带,细胞脱包囊后残留的包囊壁含15条蛋白谱带,两者共有谱带为14条,特有谱带各为8条和1条,相似度为76%。包囊游仆虫(Euplotes encysticus)的营养细胞和休眠细胞均含23条蛋白谱带,两者共有谱带为19条,特有谱带各为4条,相似度为82.6%;休眠细胞的包囊壁和细胞脱包囊后残留的包囊壁均含20条蛋白谱带,两者共有谱带为19条,特有谱带均为1条,相似度为95%。结果表明,两种纤毛虫的营养细胞向休眠细胞转化过程中,细胞结构的主要蛋白质成分发生了明显变化,这些变化与细胞在不同生理状态下结构的分化及其生命活动特征相关。形成“毛基体吸收型包囊”的急纤虫与形成“毛基体非吸收型包囊”的游仆虫相比较,前者营养期和休眠期细胞蛋白组成有更明显的差异,这可能与其细胞结构更大程度的脱分化有关;根据纤毛虫休眠细胞的包囊壁和细胞脱包囊后残留的包囊壁两者蛋白组成的差异推测,前者包囊壁可能含有与休眠细胞生命活动相联系的“活性”成分。     

Protozoa in Planktonic Food Webs1,2

Protozoa are now being recognized as important members of planktonic food webs. This is due to the inclusion of microbial links in our paradigm of trophic relationships. Heterotrophic microflagellates and ciliates are major grazers of bacteria. They can stimulate production through nutrient recycling and can transform microbial production into larger particles, which are then available for macroconsumers. In this paper we add new groups, the small (< 20 μm) ciliates and myxotrophic flagellates, to the planktonic food web.     

Parasitic Life Styles of Marine Dinoflagellates1

Several genera of marine dinoflagellates contain species that have evolved parasitic life styles. Dinoflagellate infections have been reported for a wide range of host organisms including sarcodines. ciliates, free-living dinoflagellates, various invertebrates, and a few vertebrates. Some dinoflagellates even parasitize other parasitic dinoflagellates. Most species are obligately parasitic and rely on heterotrophy as their sole means of nutrition; however, some are mixotrophic, as they possess chloroplasts during part or all of their life cycle. Many are ectoparasites that use highly specialized structures to attach to their host and feed, while others are intracellular parasites that feed by osmotrophy. Parasitic dinoflagellates often have adverse effects on their host that can lead to reproductive castration or death. The ecological importance of parasitic dinoflagellates is particularly evident during epidemic outbreaks that cause mass mortality of host organisms. Species that infect fish can pose threats to aquaculture. while other species can make commercially important crustacea unpalatable. In the planktonic realm, parasitic dinoflagellates influence the structure and function of the microbial food web. They compete with copepods and other grazers by utilizing ciliates as hosts and can stimulate rapid recycling of nutrients by causing the decline of toxic and non-toxic red tides.     

浮游被囊动物的分类及其生态学研究进展

被囊动物(Tunicata)是一类低等脊索动物,包括3个纲:有尾纲、海樽纲和海鞘纲;全部生活在海洋里,其中有尾纲和海樽纲营浮游生活。综述了国内外浮游被囊动物分类和生态研究的现状和进展,综述介绍了有尾纲和海樽纲的分类依据、研究现状、趋势和在海洋生态系统中的作用。浮游被囊动物是热带和亚热带海域重要的浮游动物类群,种类和数量的分布变化受物理和生物环境因素的影响;它一方面大量摄食浮游细菌和微小浮游植物,另一方面被一些经济动物摄食,因此在海洋食物链的传递和生态系统的物质循环中占有重要位置。     

An approach to analyzing spatial patterns in annual dynamics of planktonic ciliate communities and their environmental drivers in marine ecosystems

The environmental drivers to shape the spatial patterns in annual dynamics of the planktonic ciliate communities were studied based on an annual dataset from a bay, northern Yellow Sea. Samples were biweekly collected at five stations with different environmental condition status during a 1-year period. The second-stage-analysis-based multivariate approaches were used to reveal the internal dynamics in annual patterns of the ciliate assemblages. Results showed that: (a) there was a clear spatial variability in annual dynamics among five stations; (b) the dominant species represented different succession dynamics among four samples stations during the 1-year cycle; and (c) the spatial variations in annual patterns of the ciliates were significantly correlated with nutrients, alone or in combination with salinity and dissolve oxygen (DO). Thus, it is suggested that the nutrients may be the main drivers to shape the spatial patterns in annual dynamics of planktonic ciliate communities in marine ecosystems.     

Planktonic communities of melt ponds on the McMurdo Ice Shelf,Antarctica

The planktonic community of 20 melt ponds on the McMurdo Ice Shelf was investigated to determine taxa abundance and diversity and the controlling environmental variables. Grazing rates were measured using fluorescent beads to examine trophic interactions between ciliates, bacteria and phytoplankton. The melt ponds contained a surprisingly varied planktonic community with relatively high abundance compared with Antarctic continental lakes. There was a clear distinction between small, productive ponds dominated by bactivorous small ciliates, hymenostomes and heterotrophic cryptophytes and the larger, less productive ponds where these taxa were less abundant. The benthic mats of cyanobacteria and diatoms were potentially a source of food for some ciliate species but the majority were bacterivores. The lack of large herbivorous ciliates, the heterotrophic capabilities of cryptophytes and the broad ecological tolerances contributed to a planktonic community dominated by cryptophytes.     

Foreign Organelle Retention by Ciliates

SYNOPSIS. Intact algal chloroplasts were found by electron microscopy in the peripheral cytoplasm of 2 ecologically important species of planktonic marine ciliates. The exact origin of the chloroplast is uncertain and the periods of their retention by the protozoa is unknown. The 2 ciliate species may function partially or fully as primary producers. In other ciliates algal eye-spots are retained and may actually be utilized. Ecologic and evolutionary implications of the observations are discussed.     

Autofluorescence of marine planktonic Oligotrichina and other ciliates

Planktonic ciliates, principally from the suborders Oligotrichina and Tintinnina, were examined by epifluorescence microscopy. This allowed (1) to check if isolated symbiotic plastids demonstrated by TEM in some species could keep and show an important autofluorescence, (2) to count and identify the species presenting this characteristic, and (3) to determine their proportion compared with the other strictly heterotrophic planktonic ciliates. An average of 40.6% of the Oligotrichina species, collected during the fall and winter, diplayed a strong autofluorescence. This indicated chlorophyll contents, in a good state of activity, which most often masked the digestive vacuoles shown by TEM. It seems that the maintenance of plastids, or of symbiotic algae, is common in this sub-order. These autofluorescent ciliates are probably all mixotrophic. We suggest to call them ‘plastidic ciliates’, and to consider their role in marine primary production. Discussion deals with the origin and the role of autofluorescent pigments in the Oligotrichina, compared with the other planktonic ciliates. The interest and the limits of the methods employed up to now, or to be used in this field, are analysed. Finally the evolutionary and ecological significance of such a development of symbiosis among planktonic ciliates is discussed.     

Diversity of Oligotrichia and Choreotrichia Ciliates in Coastal Marine Sediments and in Overlying Plankton

Elucidating the relationship between ciliate communities in the benthos and the plankton is critical to understanding ciliate diversity in marine systems. Although data for many lineages are sparse, at least some members of the dominant marine ciliate clades Oligotrichia and Choreotrichia can be found in both plankton and benthos, in the latter either as cysts or active forms. In this study, we developed a molecular approach to address the relationship between the diversity of ciliates in the plankton and those of the underlying benthos in the same locations. Samples from plankton and sediments were compared across three sites along the New England coast, and additional subsamples were analyzed to assess reproducibility of methods. We found that sediment and plankton subsamples differed in their robustness to repeated subsampling. Sediment subsamples (i.e., 1-g aliquots from a single ∼20-g sample) gave variable estimates of diversity, while plankton subsamples produced consistent results. These results indicate the need for additional study to determine the spatial scale over which diversity varies in marine sediments. Clustering of phylogenetic types indicates that benthic assemblages of oligotrichs and choreotrichs appear to be more like those from spatially remote benthic communities than the ciliate communities sampled in the water above them.Planktonic ciliates provide a critical trophic link between the microbial and macroscopic components of the pelagic food web, and the subclasses Choreotrichia and Oligotrichia are the most abundant ciliate groups in this environment (46). One key to understanding the diversity and ecology of Choreotrichia and Oligotrichia is the relationship between benthic and planktonic forms. While the ciliates in these two groups are predominantly swimmers (54), there is crossover between benthic and pelagic environments for many species. Some taxa are described as epibenthic, living in the layer of water just above the sediment (16, 54), some have the capacity to live attached to sediment particles for a period and then become free-swimming (21), and a large number of taxa within these two groups spend a portion of their life cycles in dormancy, persisting in the sediments in cyst form (22, 23, 25, 35, 36, 39, 40, 41, 43, 49, 51). An accurate assessment of ciliate dynamics in the plankton requires careful study of both benthic and pelagic environments and the extent of coupling between the two environments.The role of the cyst in the life cycle of marine planktonic ciliates is particularly critical for understanding their distribution, evolutionary history, and ecology (6) as cysts provide a mechanism for dormancy during periods of poor environmental conditions. Relatively few marine ciliate species have been directly studied to determine conditions for encystment and excystment, period of dormancy (22, 23, 25, 26, 43), and role of the encystment cycle in the ecology of the organism (36). Moreover, studies on the conditions related to encystment and excystment in ciliates reveal different patterns and potential causes depending on the species (22, 23, 25, 26, 36, 43). While some data link the cycle of encystment with environmental factors such as light (23), temperature (23, 25, 26), and presence of food (22), other data suggest a temporal/seasonal cycling independent of external environmental conditions (26, 36, 43).A further factor limiting our understanding of the role of cysts in the life cycle of ciliates is identification based on the limited morphological features of the cysts, which are highly convergent (4, 17). In the case of ciliates that encyst within a lorica, as in the tintinnids, this is less of a problem (45), but for aloricate species, identification is not certain without direct observation of excystment (41, 48). Hence, morphological surveys of ciliates in benthic environments frequently capture members of the Oligotrichia and Choreotrichia (19, 31, 52, 53, 54) but are often limited to identification at the genus level using morphological approaches.More is known about planktonic ciliates, where morphology provides a wealth of data (11) and where molecular studies have revealed tremendous diversity, with many rare haplotypes (10). We define distinct sequences at the small-subunit (SSU) ribosomal DNA (rDNA) locus as haplotypes to remain conservative in our approach to identifying operational taxonomic units (OTUs) because ciliates have an unusual genome structure with high chromosome copy number, which potentially could generate multiple sequence types for the same locus within an organism or within a species. Planktonic ciliates show high molecular diversity at the SSU rDNA locus (10, 24), and primer sequences have been developed to detect ciliates from environmental samples within the subclasses Choreotrichia and Oligotrichia (10). Ciliates from these subclasses sampled across three coastal locations comprised distinct assemblages, with a few ubiquitous and abundant haplotypes (10) and many singletons (haplotypes unique to a particular sample).This study lays the groundwork for an alternative to morphological methods for analyzing benthic assemblages of oligotrichs and choreotrichs and comparing them to assemblages in the overlying water. Our goal was to compare levels of genetic diversity between sediment and plankton samples as a means of assessing the potential of methods for monitoring exchange between these two communities. There are two main questions addressed in this study: (i) are the two environments, plankton and sediment, comparable in robustness to repeated sampling using PCR, cloning, and sequencing and (ii) what is the relationship between genetic diversity of oligotrich and choreotrich ciliate communities sampled in marine sediments and in the plankton?To investigate the first question, we designed resampling experiments in plankton and sediment collections to test spatial heterogeneity as well as the robustness of repeated PCR cloning and sequencing for capturing diversity. Using two plankton samples collected by different means from the same time and place, we compared the similarity of subsamples in this environment to the similarity between separate subsamples of sediment collected at the same time and place. Additionally, we resampled DNA extracted from each of the two environments and investigated the reproducibility of repeated PCR cloning and sequencing between environmental types.To investigate the second question, we compared the diversity in sediment samples collected in the Gulf of Maine and Long Island Sound in May 2005 to previously published data from plankton samples collected at the same times and locations (10). Cluster analyses of the communities in sediment and plankton were used to determine the degree of coupling between the benthic and pelagic forms of Oligotrichia and Choreotrichia. The predicted result would be that the ciliate community observed in the plankton represents a subset of the diversity found in the benthic community, including cysts, beneath it. While the community in the plankton for many oligotrichs and choreotrichs would change depending on prevailing environmental conditions, predation, and chance, the benthic community, which includes encysted planktonic forms, should represent the longer-term diversity in a given region.