The Cultivation of Symbiote-free Marine Ciliates in Axenic Medium

SYNOPSIS. Media have been developed for axenic cultivation of 10 strains belonging to 7 species of small marine ciliates. A medium containing cerophyl extract, proteose peptone, trypticase, yeast nucleic acid, biotin, calcium pantothenate folic acid, nicotinamide, pyridoxal HCl, riboflavin, thiamine HCl, and DL-thioctic acid in sea water supports the growth of Uronema nigricans strains Pc and 34/2, Parauronema virginiatum strains 2/1 and 19/1, Miamiensis avidus strains Ma and 19/3, Miamiensis sp. strain 1/1, a strain of "G" ciliate, and strains 33/8 and 34/7 of 2 unidentified species. By substituting a mixture of asolecithin, cephalin, and Tween 80 for cerophyl in the medium, luxurious growth of all except the strains of the 2 unidentified species can be obtained. A defined medium consisting of 18 amino acids, 5 purine derivatives, 8 vitamins, asolecithin, cephalin, and Tween 80 in synthetic sea water also has been developed for 6 of the strains: M. avidus Ma and 19/3, Miamiensis sp. 1/1, P. virginiatum 2/1 and 19/1, and U. nigricans Pc. In general the ciliates grow best at pH 7.2 in the dark at 27 C in media containing sea water of density = 1.015. Under these conditions maximum populations are reached in 4–5 days and range from several hundred thousand to 3 or 4 × 10⁶ depending upon the strain. Electronmicroscopic observations for the presence of endosymbiotes gave negative results.     

Growth rate variability in geographically diverse clones of Uronema (Ciliophora: Scuticociliatida)

Abstract Growth rates in 15 clones from the bacterivorous ciliate Uronema and one from Parauronema acutum have been compared under similar culture conditions. Five species were identified on a morphological basis: U. marinum, U. nigricans, U. elegans, P. acutum , and an undescribed form designated here as SWi1 . Intra- and inter-specific distinct growth characteristics were observed. Net cellular production tended to decrease with lower growth rate in different species or morphotypes but increased in those clones belonging to the same species. Growth rate and cell volume were not significatly correlated although mean growth rate increased with mean cell volume. Growth rate was however significantly correlated to the relative variation in cell volume between different growth phases. Estimation of growth rates using different models indicated that the experimental growth rates observed were not significatly different from those expected for the cell volumes. These results indicate how effects of habitat or geographical variability, in this cosmopolitan genus, may account for trophodynamic variation of morphologically similar species.     

Observations on the Ultrastructure of Uronema spp., Marine Scuticociliates*

SYNOPSIS. Observations of the ultrastructure of marine scuticociliatids, tentatively assigned to the genus Uronema, were made by light, transmission electron, and scanning electron microscopy. Giant, cortically oriented mitochondria filled the subpellicular, intermeridional areas, and were in close association with the epiplasm immediately under the inner alveolar sac membranes. Reconstructions of serial sections of the posterior poles of ciliates indicated that the intermeridional mitochondria could fuse at that point and the entire chondriome might at times be a single organelle. A system of tubules was observed to be intimately associated with the mitochondria in the posterior region. The tubules anastomosed and were directed posteriorly into the region of the nephridial-contractile vacuole system. The outer surfaces were coated with projections arranged in helical patterns. The system may be regarded as a fluid segregation organelle. The tripartite nature of the polar basal body complex observed by silver impregnation was confirmed by transmission electron microscopy. The 3 structures were the basal body of the caudal cilium and 2 parasomal sacs. A prominent ring around the caudal cilium was observed by scanning electron micrcscopy; it is probably responsible for the silver deposition surrounding the polar basal body complex that can be seen by light microscopy of silver-impregnated specimens. The ultrastructure of the nonmotile caudal cilium and its kinetosome was unremarkable, being like that of the motile, somatic cilia. The micronuclear and macronuclear outer membranes were continuous at several sites. Such interconnections explain the intimate physical relationship between the nuclei during interphase in many ciliates, and could be a structural basis for chemical communication between the 2 nuclear types. Within the cytoplasm surrounding the opening of the cytoproct, numerous clear vesicles were observed. Their position and appearance suggested that the cytoproct may be involved in the elimination of solutions as well as solids. Food vacuoles, cortical microtubules, lamellar vesicles, disc-shaped vesicles, mucocysts, and a contractile vacuole and its pore were also observed.     

孔雀鱼暗尾丝虫病病原性确认与鉴定

近年来,随着休闲渔业的兴起,观赏鱼养殖业蓬勃发展,目前我国出口的观赏鱼类已达120多种,产品远销东南亚、日本、欧洲、美国等,年出口创汇约达2亿美元。其中孔雀鱼、剑尾鱼等小型热带观赏鱼深受养殖爱好者青睐,其贸易量约占淡水观赏鱼总贸易量的30%以上。但     

Styrax japonica supplementation diet enhances the innate immune response in Epinephelus bruneus against bacterial and protozoan infections

Kelp grouper, Epinephelus bruneus, fed for 30 days with 0% (control), 0.1%, 1.0%, and 2.0% of Styrax japonica supplementation diets, led to reductions in mortality after being challenged with a bacterium (Vibrio harveyi) and a ciliate protozoan (Uronema marinum). The enriched diets significantly increased the survival rate as compared to the controls. The phagocytic and respiratory activities were significantly increased in kelp groupers given 1.0% and 2.0% enriched diets. The complement activity, lysozyme activity, serum bactericidal activity, and total protein level significantly increased with any enriched diet against the pathogens; however antiprotease activity and myeloperoxidase levels significantly increased only with 1.0% and 2.0% enriched diets while the α2-macroglobulin level was significantly enhanced with 1.0% enriched diet. The study suggests that incorporation of S. japonica at 1.0% and 2.0% level in the diet significantly enhances the immune responses in the kelp grouper E. bruneus against V. harveyi and U. marinum.     

暗尾丝虫的形态与形态发生研究

本工作采用Chatton-Lwoff氏银浸法及Wilbert氏蛋白银染色法研究了淡水纤毛虫暗尾丝虫Uronema nigricans(Muller,1786)的形态、核器、纤毛下器、银线系及详细的形态发生过程。结果显示其口器发生与已知的同属种类海洋尾丝虫具相似的过程及形式。其口器发生及演化的基本模式可表达成: 前仔虫:原口侧膜→口侧膜,盾片; 后仔虫:原口侧膜→口侧膜,第1小膜,第2小膜,盾片; 原盾片→第3小膜。 文中另外列表比较了本属与其它属的形态发生特征,并据此建立了一新科,拟梭虫科。     

海洋尾丝虫无性生殖期间口器发生的再研究

利用蛋白银技术研究了海洋纤毛虫—海洋尾丝虫无性生殖期间的口器发生过程。结果显示其口器发生与已知的同属种类具相似的过程和形式。其口器发生及演化的基本模式可表示如下 :后仔虫的小膜 1、小膜 2来源于老口侧膜后段的增殖 ;后仔虫的口侧膜及盾片来源于老口侧膜前段的增殖 ;后仔虫的小膜 3来自于老口区盾片的增殖 ;前仔虫的口侧膜及盾片来源于老口侧膜 ,三片小膜在口器发生过程中被保留。文中根据现有的形态发生资料对尾丝虫科的系统关系进行了探讨     

Using inhibitors to investigate the involvement of cell signaling in predation by marine phagotrophic protists

Phagotrophic protists are major consumers of microbial biomass in aquatic ecosystems. However, biochemical mechanisms underlying prey recognition and phagocytosis by protists are not well understood. We investigated the potential roles of cell signaling mechanisms in chemosensory response to prey, and in capture of prey cells, by a marine ciliate (Uronema sp.) and a heterotrophic dinoflagellate (Oxyrrhis marina). Inhibition of protein kinase signal transduction biomolecules caused a decrease in both chemosensory response and predation. Inhibition of G-protein coupled receptor signaling pathways significantly decreased chemosensory response but had no effect on prey ingestion. Inhibitor compounds did not appear to affect general cell health, but had a targeted effect. These results support the idea that cell signaling pathways known in other eukaryotic organisms are involved in feeding behavior of free-living protists.     

Cinetozona pyriformis n. g., n. sp.: a Relative of the Ciliate Genera Urozona and Cinetochilum (Ciliophora, Scuticociliatida)

Cinetozona pyriformis n. g., n. sp. is a very small scuticociliate recently found in a freshwater artificial pond in Madrid, Spain. This new ciliate is here described using silver impregnation techniques. C. pyriformis bears a girdle of cilia near the equator ot the cell, similar to the genus Urozona Schewiakoff, 1889, while the oral structures resemble those in the genus Cinetochilum Perty, 1852. The ciliate's systematic position is discussed, and its inclusion in the family Cinetochilidae is proposed.