The nucleotide sequences of 5S rRNAs from three ciliated protozoa.

The nucleotide sequences of 5S rRNAs from three ciliated protozoa, Paramecium tetraurelia, Tetrahymena thermophila and Blepharisma japonicum have been determined. All of them are 120 nucleotides long and the sequence of probable tRNA binding site of position 41-44 is GAAC which is characteristic of the plant 5S rRNAs. The sequence similarity percents are 87% (Paramecium/Tetrahymena), 86% (Paramecium/Blepharisma) and 79% (Tetrahymena/Blepharisma), suggesting a close relationship of these three ciliates.     

A rhodopsin immunoanalog in the related photosensitive protozoans Blepharisma japonicum and Stentor coeruleus

Immunoblotting of isolated cell membrane fractions from ciliates Blepharisma japonicum and Stentor coeruleus with a polyclonal antibody raised against rhodopsin revealed one strong protein band of about 36 kDa, thought to correspond to protozoan rhodopsin. Inspection of both ciliates labeled with the same antibody using a confocal microscope confirmed the immunoblotting result and demonstrated the presence of these rhodopsin-like molecules localized within the cell membrane area. Immunoblot analysis of the ciliate membrane fractions resolved by two-dimensional gel electrophoresis identified two distinct 36 kDa spots at pIs of 4.5 and 7.0 for Blepharisma, and three spots at pIs of 4.4, 5.0 and 6.0 for Stentor, indicating a possible mixture of phosphorylated rhodopsin species in these cells. The obtained results suggest that both Blepharisma and the related ciliate Stentor contain within the cell membrane the rhodopsin-like proteins, which may be involved as receptor molecules in the sensory transduction pathway mediating motile photoresponses in these protists as in other species of lower eukaryota.     

Phylogenetic Relationships of Blepharisma Americanum and Colpoda Inflata Within the Phylum Ciliophora Inferred From Complete Small Subunit Rrna Gene Sequences

ABSTRACT The complete small subunit rRNA gene sequences of the heterotrich Blepharisma americanum and the colpodid Colpoda inflata were determined to be 1719 and 1786 nucleotides respectively. the phylogeny produced by comparisons with other ciliates indicated that C. inflata is allied more closely with the nassophoreans and oligohymenophoreans than the spirotrichs. This is consistent with the placement of the colpodids in the Class Copodea. Blepharisma americanum was not grouped with the hypotrichs but instead was placed as the earliest branching ciliate. the distinct separation of B. americanum supports the elevation to class status given the heterotrichs based on morphological characters.     

中国土壤原生动物新纪录种(纤毛虫门：多膜纲；异毛目)

报道了首次在中国土壤中鉴定到的、隶属于纤毛虫门多膜纲异毛目的７种原生动物。这些种类是泥炭藓苔扭虫、透明赭虫、长赭虫、透明扭头虫、弯曲扭头虫、旋短端突虫和梅氏扁豆虫。     

Taxonomy of Genus Blepharisma with Special Reference to Blepharisma undulans

SYNOPSIS. Three new species of Blepharisma are presented: B. seshachari sp. nov., B. intermedium sp. nov., and B. tropicum sp. nov. Two sub-species of Suzuki are elevated to specific rank, B. undulans americanum to B. americanum and B. undulans japonicum Suzuki to B. japonicum Suzuki. Stein's taxa for the species Blepharisma undulans are considered to be diagnostic for that species.
Important features of morphology and life-cycle of the above mentioned species are given. Discussion and position of the species Blepharisma undulans are presented and a proposal for the reorganization of the species is made. The possibility of a new key derived from a hypothesis of the phylogeny on an evolutionary basis of the genus is presented. This hypothesis has been extended to include ciliates like Stentor and Spirostomum and its implications discussed.     

A Proposed Organization of the Genus Blepharisma Perty and Description of Four New Species

SYNOPSIS. The following four subgenera. I based chiefly on the form of the macronucleus, are proposed for thr genus Blepharisma Perty 1852: 1) Compactum , having a single compact interphase macronucleus. Type species B Compactum hyalinum Perty. 2) Filijormis , having a vermiform or tubular elongate interphase macronuclcus. occasionally doubled or even fragmented in individuals. Type spcies B. (Filiformis) intermedium Bhandary. 3) Blepharisma , having an interphase macronucleus with two or more nodes usually connected by a very thin strand between the nodes. Type species B. (Blepharisma) Perisicinum Perty. 4) Halteroides , having an interphase macronucleus in two nodes connected by a thick strand. Type species B. (Halteroides) tropicum Bhandary. Differences between the subgenera also can be found in the size, pigmentation, presence or absence of cysts and conjugaion 26 species are presented.
While integradations between the subgenera and species exist, it is felt that separation of the four groups is warranted and may indicate possible evolutionary trends within the genus.     

Chemosensory Response in Blepharisma. I. Accumulation of Cells in Products of Bacterial Metabolism

ABSTRACT. Blepharisma cells were attracted by a pellet of live bacteria (Enterobacter) which was separated from the Blepharisma suspension by a cellulose membrane (fractionation: M.W. 14,000). The cells, however, were not attracted by killed bacteria. Crude and heat-treated supernatants obtained from bacterial suspension also induced chemoaccumulation of cells. These results suggest that the cells of Blepharisma detect certain small molecules, produced by live bacteria, that can pass through the cellulose membrane and are stable to heat. From the live bacteria supernatant, several ninhydrin-positive substances were isolated by means of two-dimensional thin-layer chromatography. Several of the spots contained substances that attracted the cells, indicating that certain ninhydrin-positive components, such as peptides or free amino acids (probably products of bacterial metabolism), may serve as a signal for food.     

赭纤虫RNA聚合酶Ⅰ基因片段的分析

赭纤虫被认为是一类进化过程中较为原始的纤毛虫。本研究以储纤虫基因组DNA为模板,利用锚定PCR技术,扩增出RNA聚合酶I第二大亚基基因片段,并对扩增出的基因片段进行了克隆和序列分析。结果表明：由该基因片段导出的氨基酸序列中共有10个半胱氨酸,均由通用密码子UGU、UGC编码,开放读框中不存在由UGA转译为半眈氨酸这一非通用密码的现象。     

Phylogenetic relationships of Blepharisma americanum and Colpoda inflata within the phylum ciliophora inferred from complete small subunit rRNA gene sequences

The complete small subunit rRNA gene sequences of the heterotrich Blepharisma americanum and the colpodid Colpoda inflata were determined to be 1719 and 1786 nucleotides respectively. The phylogeny produced by comparisons with other ciliates indicated that C. inflata is allied more closely with the nassophoreans and oligohymenophoreans than the spirotrichs. This is consistent with the placement of the colpodids in the Class Copodea. Blepharisma americanum was not grouped with the hypotrichs but instead was placed as the earliest branching ciliate. The distinct separation of B. americanum supports the elevation to class status given the heterotrichs based on morphological characters.     

DNA-Dependent RNA Synthesis in Isolated Macronuclei of Blepharisma intermedium (Ciliata)

SYNOPSIS. Autoradiographic studies on DNA-dependent RNA synthesis in isolated macronuclei of Blepharisma intermedium in vitro are described. Isolated macronuclei incubated in a medium containing RNA precursors incorporated cystidine and uridine into RNA. Uptake of cystidine was greater than that of uridine. Addition of ATP did not appreciably affect the uptake of precursors into RNA. Actinomycin D (5 μg/ml) blocked incorporation of cystidine and uridine. It is concluded that in isolated macronuclei of Blepharisma , RNA precursors are 1st converted into triphosphates and then incorporated into RNA thru DNA-dependent RNA polymerase.     

The Effects of Temperature on Blepharisma intermedium

SYNOPSIS. An initial rise in temperature increases the reproductive rate in Blepharisma intermedium; after it reaches the maximum, it gradually declines and finally fission is blocked. Cytochemical investigations made on Blepharisma acclimated to 28 C—the temperature at which the reproductive rate is maximum—show that conditions are optimum for cell division. Requisite quantities of glycogen, basic proteins, unsaturated lipids, enzymes alkaline and acid phosphatases are present. At 38 C the cell metabolism is altered, there is a decrease in the quantity of glycogen reserves, proteins and lipids, the enzyme activity diminishes, the free amino acid pattern changes and cell division is blocked. However, this block is transitory. Upon return to room temperature and when fresh culture medium is added, after a lag of 3 days, the cell metabolism becomes normal and the ciliates resume fission.     

Cytology of an Indian Race of Blepharisma undulans (Stein)

SYNOPSIS. The Indian race of Blepharisma undulans described in this paper measures 150 μ in length. The macronucleus consists of 5–7 nodes, all of equal size. During binary fission, condensation of macronucleus is followed by its elongation and a thinning of the middle region which breaks with the division of the animal. It later attains the typical vegetative form.
During conjugation 7 or 8 micronuclei pass through the first pregamic division, 5 to 7 through the second pregamic division and one product of the second division takes part in the third division. The rest degenerate. At the same time, the macronucleus also starts degenerating. After the synkaryon has divided twice, the conjugating pairs separate. Of the 4 products, 3 become macronuclear anlagen and one, micronuclear anlage.
The micronuclei divide asynchronously both during binary fission and during conjugation. There is apparently considerable diversity in the structure and behaviour of the macronucleus and micronuclei in the different races of Blepharisma undulans.     

Non-Mendelian Inheritance in Blepharisma intermedium

SYNOPSIS. An albino mutation of Blepharisma intermedium (a dark red ciliate) has been isolated. The inheritance of factors controlling pigmentation, mating-type, and lethality level of sexually derived offspring has been studied. All 3 traits are inherited in a non-Mendelian manner, perhaps via the cytoplasm.     

Synthesis of fluorescent molecular probes specific for the receptor of blepharismone, a mating-inducing pheromone of the ciliate Blepharisma japonicum

Blepharismone (gamone 2) is a mating-inducing pheromone of the ciliate Blepharisma japonicum. N-Pyrenylbutyryl-blepharismone and N-biphenylacetyl-blepharismone, which are fluorescent derivatives of blepharismone, were synthesized as molecular probes for the gamone 2 receptor. Further, we proved that they have inhibitory activities against the blepharismone-induced monotypic pairing of B. japonicum.     

Highly divergent actins from karyorelictean, heterotrich, and litostome ciliates

We have cloned, sequenced, and characterized cDNA of actins from five ciliate species of three different classes of the phylum Ciliophora: Karyorelictea (Loxodes striatus), Heterotrichea (Blepharisma japonicum, Blepharisma musculus), and Litostomatea (Didinium nasutum, Dileptus margaritifer). Loxodes striatus uses UGA as the stop codon and has numerous in-frame UAA and UAG, which are translated into glutamine. The other four species use UAA as the stop codon and have no in-frame UAG nor UGA. The putative amino acid sequences of the newly determined actin genes were found to be highly divergent as expected from previous findings of other ciliate actins. These sequences were also highly divergent from other ciliate actins, indicating that actin genes are highly diverse even within the phylum Ciliophora. Phylogenetic analysis showed high evolutionary rate of ciliate actins. Our results suggest that the evolutionary rate was accelerated because of the differences in molecular interactions.     

Improved Method for Axenizing Blepharisma by Means of Antibiotics

Synopsis.
A simplified method for obtaining axenic cultures of Blepharisma involves the use of penicillin, streptomycin, and tetracycline. Cytologic examination disclosed no significant effect of these antibiotics on the structure of the ciliates.     

Macronuclear Variation During the Life Cycle of Blepharisma dawsoni n.sp. and B. wardsi

SYNOPSIS. From characteristics of binary fission, conjugation, size and number of micronuclei, body size and incidence of giantism, a Blepharisma isolate hitherto called B. undulans is classified as B. dawsoni sp. nov. Binary fission in B. wardsi differs from fission in B. dawsoni in that the strand connecting the macronuclear nodes is severed; in B. dawsoni the strand persists.     

Asymmetrical cell division in Blepharisma japonicum: difference between daughter cells in mating-type expression

In cell division of high-frequency-selfers in the ciliate Blepharisma japonicum, daughter cells are different in mating-type expression. The anterior daughter cell is mating type I. The posterior daughter cell is mating type II at first and then changes to mating type I after about 24 h. The anteroposterior polarity of predivision cells appears to correlate with the asymmetrical cell division. This work introduces a unicellular organism about the size of microscopic metazoa as a model system for the study of asymmetrical cell division, which is particularly important in developmental processes.     

Effects of enrichment on protist abundances and bacterial composition in simple microbial communities

We experimentally investigated effects of nutrient enrichment and trophic structure in a microbial food web consisting of mixed bacteria, two bacterivorous ciliates ( Tetrahymena sp. and Colpidium sp.) and an omnivorous ciliate ( Blepharisma sp.) feeding on both trophic levels. We assembled all possible food webs including one or more of the ciliate species and cross-classified them with four levels of enrichment of the bacterial medium. The qualitative outcome of food web interactions was independent of enrichment and always the same: Tetrahymena strongly depressed or excluded Colpidium , and Blepharisma strongly depressed or excluded both bacterivores. Consequently, in all sub-webs only the dominant ciliate species responded positively to enrichment. The total density of bacteria increased with enrichment irrespective of food web composition. In contrast, the response of single-celled bacteria to enrichment depended on food web composition and was only weakly positive in most food webs with the omnivore. Enrichment had a positive effect on the relative success of (presumably more defended) bacterial aggregates. The outcome of interspecific interactions among ciliates could not be predicted from monoculture experiments and deviated from earlier experiments in which each bacterivore coexisted separately with the omnivore. As a potential explanation we suggest that changes in experimental protocol reduced spatial heterogeneity and increased attack rates. A simple, dynamical model shows that increased attack rates can indeed greatly decrease the upper limit and range of enrichment over which intermediate consumers can coexist with omnivores.     

Identification of possible phosducins in the ciliate Blepharisma japonicum

Examination of ciliate Blepharisma japonicum whole cell lysates with an antibody against phosphoserine and in vivo labeling of cells with radioactive phosphate revealed that the photophobic response in the ciliate is accompanied by a rapid dephosphorylation of a 28 kDa protein and an enhanced phosphorylation of a 46 kDa protein. Analysis with antibodies raised against rat phosducin or human phosducin-like proteins, identified one major protein of a molecular weight of 28 kDa, and two protein bands of 40 kDa and 93 kDa. While the identified ciliate phosducin is phosphorylated in a light-dependent manner, both phosducin-like proteins exhibit no detectable dependence of phosphorylation upon illumination. An immunoprecipitation assay also showed that the ciliate phosducin is indeed phosphorylated on a serine residue and exists in a phosphorylated form in darkness and that its dephosphorylation occurs in light. Immunocytochemical experiments showed that protozoan phosducin and phosducin-like proteins are localized almost uniformly within the cytoplasm of cells adapted to darkness. Cell exposure to light caused a pronounced displacement of the cell phosducin to the vicinity of the plasma membrane; however, no translocation of phosducin-like proteins was observed upon cell illumination. The obtained results are the first demonstration of the presence and morphological localization of a possible phosducin and phosducin-like proteins in ciliate protists. Phosducin and phosducin-like proteins were found to bind and sequester the betagamma-subunits of G-proteins with implications for regulation of G-protein-mediated signaling pathways in various eukaryotic cells. The findings presented in this study suggest that the identified phosphoproteins in photosensitive Blepharisma japonicum may also participate in the regulation of the efficiency of sensory transduction, resulting in the motile photophobic response in this cell.