Search

Highlights • Direct sequencing of PCR products captured the dominant ITS and LSU haplotypes. • Deep cloning was deemed more appropriate for the COI gene for population level studies. • P. multinucleatum populations might origin from a single founder population. • Only dominant sequence of temporal populations passed on to subsequent generations. Abstract Questions regarding ciliate distribution (endemism vs. cosmopolitanism) and degree of genetic diversity (high vs. low) remain unsettled, even when the same organism is under investigation. Presence of genes with high copy number and amplification of non-dominant haplotypes might account for the observed discordance in these studies. Herein, we used direct PCR and cloning sequencing to examine intra-population sequence diversity and its effect on assessments of phylogeography of Paramecium multimicronucleatum. Totally, 381 ITS1-5.8S rDNA-ITS2-28S rDNA and 304 mitochondrial cytochrome oxidase subunit I (COI) gene sequences were generated for 18 populations of P. multimicronucleatum. The following results were obtained: (1) Direct sequencing of PCR products captured the dominant ITS and LSU haplotypes, indicating that it is an appropriate strategy for constructing phylogeography of large-scale spatial populations. (2) Deep cloning was deemed more appropriate for the COI gene for population level studies, as direct sequencing could not easily capture the dominant haplotypes. (3) No endemic populations of P. multinucleatum were noted, indicating origin from a single founder population. (4) Nuclear genetic diversity within temporal populations was high, but only the dominant haplotypes seemed to be passed on to subsequent generations. [ABSTRACT FROM AUTHOR]

Macronuclear chromosomes of ciliates, especially those of Spirotrichea, Armophorea and Phyllopharyngea, are extensively fragmented and their copy numbers vary significantly. A recent study suggested that parental RNA molecules regulate macronuclear copy number in offspring cells after conjugation. However, variations in patterns of macronuclear copy number during vegetative growth are not clear. Previous studies have reported macronuclear copy numbers of population averages, potentially masking individual variation. In the present investigation, we studied copy number variations among closely related species of Pseudokeronopsis and among individual cells during vegetative growth. We found that macronuclear copy numbers of Actin I , II in our Pseudokeronopsis populations are in the same range as in other spirotrichean species, but no close relationship is detected among morphologically related Pseudokeronopsis species. Copy numbers of three cells within each Pseudokeronopsis population range from 1.01 to 4.55 fold, suggesting that stochastic influences copy number during vegetative growth. Furthermore, the absence of a relationship between macronuclear copy numbers of Actin I and Actin II within Pseudokeronopsis is consistent with the fact that these genes are located on different gene-sized macronuclear chromosomes. Additionally, Actin II might have disappeared in P. carnea during evolution within the Actin gene family. [ABSTRACT FROM AUTHOR]

Seven marine scuticociliates, Philaster sinensis spec. nov., Pseudocohnilembus hargisi Evans and Thompson, 1964. J. Protozool. 11, 344, Parauronema virginianum Thompson, 1967. J. Protozool. 14, 731, Uronemella filificum (Kahl, 1931. Tierwelt. Dtl. 21, 181) Song and Wilbert, 2002. Zool. Anz. 241, 317, Cohnilembus verminus Kahl, 1931, Parauronema longum Song, 1995. J. Ocean Univ. China. 25, 461 and Glauconema trihymene Thompson, 1966. J. Protozool. 13, 393, collected from Chinese coastal waters, were investigated using live observations, silver impregnation methods, and, in the case of the new species, SSU rDNA sequencing. Philaster sinensis spec. nov . can be recognized by the combination of the following characters: body cylindrical, approximately 130–150 × 35–55 μm in vivo; apical end slightly to distinctly pointed, posterior generally rounded; 19–22 somatic kineties; M1 triangular, consisting of 13 or 14 transverse rows of kinetosomes; M2 comprising 10–12 longitudinal rows; CVP positioned at end of SK1; marine habitat. We also provide improved diagnoses for Pseudocohnilembus hargisi , Parauronema virginianum , Uronemella filificum and Parauronema longum based on their original descriptions as well as the present work. Phylogenetic analyses support the monophyly of the genus Philaster . [ABSTRACT FROM AUTHOR]

In the present study, a new freshwater peniculid species, Frontonia apoelegans sp. nov., and two other peniculid species, Frontonia atra (Ehrenberg, 1833) Bütschli, 1889 and Stokesia vernalis Wenrich, 1929, were isolated from Lake Weishan wetland, northern China. Their morphology and infraciliature are described based on live observations and silver staining methods. The SSU rRNA gene sequences are also provided. Frontonia apoelegans sp. nov. is recognized by the following combination of characteristics: two contractile vacuoles located right-dorsally, without collecting canals; peniculi 1 and 2 four-rowed, peniculus 3 three-rowed with leftmost row containing only one kinetosome; 62–76 somatic kineties; three ophryokineties; and four or five postoral kineties. We also provide improved diagnoses for Frontonia atra and Stokesia vernalis based on current and previous reports. Comparisons with sequences of morphologically similar species clearly support the validity of the new species. Phylogenetic analyses based on SSU rRNA gene sequence data reveal that Frontonia species with two contractile vacuoles cluster in a single clade, indicating these species may have a common origin. The family Frontoniidae is non-monophyletic whereas the family Stokesiidae remains monophyletic according to our analyses. [ABSTRACT FROM AUTHOR]

Abstract: In environmental studies, some biological responses, known as biomarkers, have been used as a powerful bioassay tool for more than four decades. Disparity between enzyme activity and mRNA abundance leads to correlation equivocality, which makes the application of biomarkers for environmental risk assessment more complicated. This study investigates this disparity in the case of catalase when used as a biomarker for detecting ecotoxicity induced by antibiotics in aquatic ecosystems. In particular, dose–responses for catalase activity and mRNA expression abundance were investigated in Euplotes vannus which were exposed to graded doses of nitrofurazone for several discrete durations, and dose–response models were developed to characterize the dose–response dynamics. Significant differences were found in both catalase activity and mRNA expression abundance among the E. vannus treated with nitrofurazone. Catalase activity showed a hormetic-like effect in terms of dose–response, characterized by a biphasic relationship which was more clearly evident after a longer exposure period, while mRNA expression abundance increased linearly with the exposure duration. Additionally, the correlation between catalase activity and mRNA expression abundance reversed along with the duration of exposure to nitrofurazone. Taken together, our results demonstrate that catalase mRNA expression offers a more straightforward dose–response model than enzyme activity. Our findings suggest that both catalase enzyme activity and mRNA expression abundance can be used jointly as bioassay tools for detecting ecotoxicity induced by nitrofurazone in aquatic ecosystems. [Copyright &y& Elsevier]

Abstract: Aiming at students’ learning process, and based on the analysis of tutorship rules of students’ learning after class, a Knowledge-Based Intelligent Tutoring System is given. The system comprehensively uses agent technology, the knowledge-based automatic reasoning, resource modeling for knowledge classification, field natural language understanding, data mining, computer networks, databases and other technologies [Copyright &y& Elsevier]

Abstract: Traditionally the unusual ciliate Paraspathidium has been regarded as a gymnostome haptorid (Litostomatea) based on its morphological features. In order to test this placement, the small-subunit (SSU) rRNA gene was sequenced for two isolates of Paraspathidium apofuscum and phylogenetic trees were constructed. Furthermore, the putative structure of the variable regions 2 and 4 of the SSU rRNA gene were predicted and compared with those of other ciliates. Our analyses of SSU rRNA gene sequences revealed (i) a clear separation of Paraspathidium from the haptorids and indeed the class Litostomatea, rejecting its systematic position based on morphological characters and (ii) an equally clear association with the assemblage comprising the classes Plagiopylea and Prostomatea. Putative secondary structures of the variable regions 2 and 4 of Paraspathidium are similar to those of the plagiopyleans and prostomateans but differ from the hapotrids in Helix 10, Helix E10-1 and Helix E23-5. Taken together, these results support the placement of Paraspathidium close to prostomateans and plagiopyleans, or even as a distinct group possibly at ordinal rank, within the class Plagiopylea. [ABSTRACT FROM AUTHOR]

Abstract: The morphology and infraciliature of a new ciliate, Aspidisca hongkongensis spec. nov., a large marine form isolated from the coastal waters near Hong Kong, were investigated. It differs from the congeners by the combination of cell size (about 90×60μm in vivo), 9–11 conspicuous dorsal ridges, one fine and seven strong frontoventral cirri, six membranelles in anterior portion of adoral zone, and 17–23 membranelles in posterior portion of adoral zone. The comparison with similar congeners clearly supports the distinction of this new species based on morphological and small subunit (SSU) rRNA gene sequence studies. The SSU rRNA gene sequence similarity within the genus is about 75.3–92.1% which indicates that this is a distinct form. Phylogenetic trees based on SSU rRNA gene information show that A. hongkongensis groups with A. leptaspis. [Copyright &y& Elsevier]

Abstract: The morphology, morphogenesis and small subunit rRNA (SSrRNA) gene sequence of a new marine euplotid ciliate, Diophrys apoligothrix spec. nov., isolated from a sandy beach near Qingdao, north China, were investigated. This organism is characterized as follows: rigid body with a sculptured surface; size in vivo about 60–110×40–70μm; adoral zone comprising about 28 membranelles; five frontal, two ventral, five transverse, one left marginal and three caudal cirri; five dorsal kineties with sparsely distributed dikinetids; two ellipsoid macronuclear nodules; marine habitat. Although the main morphogenetic events are similar to those reported in other congeners, three features are noteworthy: (1) the parental adoral zone is retained almost unchanged by the proter except for the outer margin of membranelles in the proximal portion, where the de-differentiation and then reorganization take place in situ in the mid-to-late phases of division; (2) the dorsal kinety anlagen are formed via a two-step mode; (3) the marginal cirrus anlage is formed de novo near the old structure and does not divide. Based on the morphological, morphogenetic and SSrRNA gene sequence data, it was concluded that D. apoligothrix is a well-outlined and distinctive member of the genus Diophrys. [Copyright &y& Elsevier]

Abstract: The small subunit rRNA (SSrRNA) genes of seven species of urostyloids representing four genera were sequenced. These were: Apokeronopsis crassa, A. bergeri, Anteholosticha sp-QD-1, Metaurostylopsis sp-QD-1, M. sp-QD-2, M. sp-QD-3 and Thigmokeronopsis sp-QD-1. Gene trees were constructed in order to investigate their phylogenetic relationships. The results indicate that: (1) Apokeronopsis, Thigmokeronopsis and Metaurostylopsis form a well-supported, clearly isolated, monophyletic group; (2) Metaurostylopsis species analysed consistently group together indicating that it is a well-outlined genus; (3) the validity of the genus Apokeronopsis is supported; (4) the separation of Holosticha and Anteholosticha is supported although Anteholosticha species exhibit a high molecular diversity; (5) Pseudokeronopsis and Thigmokeronopsis, which have been considered closely related, may not share a recent common ancestor, casting doubt on the monophyly of the family Pseudokeronopsidae. [Copyright &y& Elsevier]

Abstract: The morphology and morphogenesis of a new marine hypotrich ciliate, Apokeronopsis bergeri nov. spec., collected from mussel-farming waters near Qingdao, China, are described from living and protargol-impregnated specimens. This ciliate has characteristics that place it in the family Pseudokeronopsidae, namely, two long rows of frontal cirri (bicorona), which are continuous with the long midventral rows, and a single row of marginal cirri on each side of the body. It shares with its only congener, Apokeronopsis crassa, the long rows of buccal and transverse cirri and the wide spacing between the midventral rows of cirri. These characters separate the genus Apokeronopsis from Pseudokeronopsis, which has a single buccal cirrus, fewer transverse cirri and midventral rows of cirri arranged in a typical zig-zag pattern. A. bergeri differs from A. crassa in its shape, colour and in the numbers of membranelles and transverse cirri. Although morphogenesis in A. bergeri is similar to that of A. crassa in most respects, the mode of formation of the buccal cirri is slightly different. The close relationship of A. bergeri with A. crassa, and the more distant relationship with three Pseudokeronopsis species, is supported by a comparison of the sequences of their ITS1-5.8S-ITS2 rDNA regions. [Copyright &y& Elsevier]

Abstract: The gene coding for the small subunit ribosomal RNA molecule was sequenced in three marine spirotrichs: Pseudoamphisiella lacazei, P. alveolata, and Parabirojimia similis, the systematic positions of which remain unclear in spite of recent progress. Phylogenetic trees were constructed by means of neighbor-joining (NJ), least-squares (LS), maximum parsimony (MP), and Bayesian inference (BI) methods in order to test previously inferred phylogenetic assignments of Pseudoamphisiella and Parabirojimia based on morphological and morphogenetic data. The main results are that: (1) all trees constructed have similar topologies in which the genus Parabirojimia derives at the base of the class Stichotrichia, which suggests that it might represent a unique taxon at about suborder or even-order level near urostylids; (2) the present study supports the conclusion reported by previous researchers that urostylids could be a paraphyletic assemblage and that Uroleptus and Paruroleptus should be removed from the order Urostylida; (3) Pseudoamphisiellidae/Pseudoamphisiella always clusters with Prodiscocephalus borrori rather than with urostylids, which indicates that they might represent an ancestral form for both discocephaline and urostylid species; (4) the monophyly of the traditional suborder Discocephalina and typical euplotids is consistently rejected. Based on both morphological/morphogenetical and molecular data obtained, a new suborder Parabirojimina n. subord. is suggested, which currently includes one family, Parabirojimidae n. fam., and the single genus Parabirojimia. [Copyright &y& Elsevier]

Abstract: The cortical development during binary fission of the relatively poorly known stichotrich ciliate, Trachelostyla pediculiformis (Cohn, 1866) Borror, 1972, found in coastal waters near Qingdao, China, was investigated using the protargol impregnation method. The morphogenetic process reveals some pretty unusual characteristics, which do not follow the Oxytricha-pattern: (1) the parental oral apparatus is entirely renewed from an oral primordium formed de novo in the proter; (2) in the proter, the parental undulating membranes are not involved in the formation of the newly formed oral primordium; both undulating membrane-anlagen (UM-anlage) and frontoventral-transverse cirral anlagen (FVT-anlagen) develop from the oral primordium in the proter; (3) the dorsal kineties (DK) are generated in a unique way, that is, in both dividers, two separate groups of DK-anlagen develop in the right- and left-most DK, generate all the DK and evolve to replace the old structures; (4) three caudal cirri are formed at the posterior ends of three right-most dorsal kinety anlagen; (5) eight frontal, five ventral and five transverse cirri are derived from six streaks, namely, the UM-anlage and 5 FVT-anlagen; the cirri are segregated from these anlagen in the pattern 1:3:3:3:4:4 (from left to right) in the Oxytricha mode. Based on both SSrRNA gene sequencing and morphogenetic data, the systematic positions of the genus Trachelostyla Borror, 1972 as well as the family Trachelostylidae Small and Lynn, 1985 are briefly analyzed. The results indicate that this genus/family could be a highly isolated lineage and might be ancestral to other well-known oxytrichids. [Copyright &y& Elsevier]

Two novel hypotrichous ciliates, Hemiurosomoida warreni nov. spec. and Hemiurosoma clampi nov. spec., isolated from soil in the Lhalu Wetland and Motuo Virgin Forest in Tibet, respectively, were investigated using live observation and protargol staining. Hemiurosomoida warreni nov. spec. strongly resembles the type species H. longa but can be distinguished by its body size in vivo (110–145 × 30–40 μm vs. 50–100 × 18–40 μm), number of adoral membranelles (25–38 vs. 15–22), and numbers of right (29–39 vs. 14–23) and left (26–35 vs. 13–23) marginal cirri, transverse cirri (3 vs. 4 or 5) and macronuclear nodules (4–8 vs. 2). Hemiurosoma clampi nov. spec. is characterized by its vermiform body shape, colourless cortical granules distributed in irregular rows, two macronuclear nodules, three frontal cirri, one buccal cirrus, four frontoventral cirri ranged in a line, two transverse cirri, lacking postoral ventral and pretransverse ventral cirri, and marginal rows that are not posteriorly confluent. Phylogenetic analyses based on SSU rDNA gene sequences suggest that Hemiurosomoida is not monophyletic. A close relationship is revealed between Hemiurosomoida warreni nov. spec., Parakahilella macrostoma , Hemiurosoma clampi nov. spec., and the type species Hemiurosoma terricola. As expected, all these species are classified within the "non-oxytrichid Dorsomarginalia". [ABSTRACT FROM AUTHOR]