The cyrtophorian ciliates, which have been found worldwide, are a highly specialized and divergent group (Agamaliev, 1983, Baldock et al., 1983, Borror, 1972, Carey, 1992, Deroux, 1970, Dragesco, 1966). To date, more than 160 morpho-species have been reported, although information regarding the ciliary pattern is only available for less than half of them. The series of researches conducted by Deroux, 1970, Deroux, 1974, Deroux, 1976a, Deroux, 1976b, Deroux, 1976c, which revealed the ciliary patterns of most cyrtophorian genera, are usually regarded as a milestone in taxonomic studies of cyrtophorians. Subsequently, numerous studies concerning this group have been published (e.g., Blatterer and Foissner, 1992, Chen et al., 2011, Foissner, 1988, Foissner et al., 1991, Gong et al., 2002, Gong et al., 2005a, Shao et al., 2008, Song, 2003). However, most of these works lack molecular data and some even lack detailed live observations (Warren et al. 2017). Therefore, redescriptions are still important for this group.
Trithigmostoma Jankowski, 1967 was established based on the characteristic of its continuous ventral kineties, which differs from the ciliary patterns of other chilodonellids (Jankowski 1967). Its validity was further supported by recent molecular phylogenetic investigations (Chen et al., 2016, Gao et al., 2012, Wang et al., 2017). Although Trithigmostoma is common in freshwater, only two species are contained in GenBank database, and most species are yet to be redescribed. The history of Aegyria Claparède and Lachmann, 1859 is much more complicated with two synonyms, namely, Genotrochilia Diesing, 1866 and Aegyriana Deroux, 1975 (Chen et al. 2012). Both its morphological and molecular characters strongly support its assignment to the family Hartmannulidae Poche, 1913. Following recent investigations, several new members have been assigned to this group, and such studies have indicated that the body shape and size, the number of somatic kineties, the number of nematodesmal rods, and the number of transpodial segments are all reliable characters for species separation (Chen et al., 2012, Qu et al., 2017).
During the last decade, a series of investigations concerning ciliated protozoa have been carried out in the coastal waters of China, and over 40 new or previously poorly known cyrtophorid ciliates have been reported (Chen et al., 2012, Fan et al., 2014, Gong and Song, 2006a, Gong and Song, 2006b, Gong et al., 2007, Gong et al., 2008, Liu et al., 2017, Pan et al., 2012, Pan et al., 2013a, Pan et al., 2013b, Pan et al., 2016, Pan et al., 2017, Qu et al., 2015a, Qu et al., 2015b, Qu et al., 2017). These studies have revealed that the diversity of marine cyrtophorians has been underestimated, especially in the undersampled habitats, e.g. subtropical coastal waters and mangrove wetlands.
As a new contribution, we collected two cyrtophorians. After morphological and molecular studies were performed using state-of-the-art methods (Warren et al. 2017), we found that one represented a new member of the genus Aegyria, named Aegyria apoliva sp. nov., while the other was an estuarine population of Trithigmostoma cucullulus (Müller 1786) Jankowski, 1967, whose morphology was already well investigated, but SSU rDNA is revealed here for the first time.
Material and Methods
Sample collection, observation and identification (Fig. 1a–c). Aegyria apoliva sp. nov. was isolated from glass slides, which were immersed in coastal water off Qingdao (salinity 28.5‰ and water temperature about 20 °C) for 9 day to form biofilms (Gong et al. 2005b) (Fig. 1a, b) on June 26, 2008. The Guangzhou population of Trithigmostoma cucullulus was sampled from the Pearl River estuary (salinity 4.3‰ and water temperature about 27 °C) (Fig. 1a, c) on November 9, 2008.
The isolated cells were
Results and Discussion
Order Dysteriida Deroux, 1976
Family Hartmannulidae Poche, 1913
Genus Aegyria Claparède and Lachmann, 1859
Aegyria apoliva sp. nov.(Table 1;Figs. 2a–c, 3a–j)
Diagnosis. Marine Aegyria 100–120 × 50–70 μm in vivo; body shape generally broadly oval with a protrusion and dark pigment spot on anterior left body portion; 48–69 somatic kineties; one preoral and four or five circumoral kineties; 9–13 transpodial segments; 26–40 nematodesmal rods; 6–10 contractile vacuoles; single juxtaposed heteromerous
This work was supported by the National Natural Science Foundation of China (Projects number: 31401954, 31772431) and China Postdoctoral Science Foundation (Project numbers: 2014M550378 and 2015T80753). Many thanks are due to Prof. Weibo Song, Ocean University of China, for his helpful suggestions on preparing the manuscript. We are grateful to Prof. Shan Gao, Ocean University of China for her help on DNA sequencing. Furthermore, we greatly appreciate the help of two anonymous reviewers and the
Elemental sulfur reduction to H2S by Tetrahymena thermophila
European Journal of Protistology, Volume 62, 2018, pp. 56-68
Eukaryotic nucleocytoplasm is believed to be descended from ancient Archaea that respired on elemental sulfur. If so, a vestige of sulfur reduction might persist in modern eukaryotic cells. That was tested in Tetrahymena thermophila, chosen as a model organism. When oxygenated, the cells consumed H2S rapidly, but when made anoxic they produced H2S mostly by amino acid catabolism. That could be inhibited by adding aminooxyacetic acid, and then H2S production from elemental sulfur became more evident. Anoxic cell lysates produced H2S when provided with sulfur and NADH, but not with either substrate alone. When lysates were fractionated by centrifugation, NADH-dependent H2S production was 83% in the soluble fraction. When intact cells that had just previously oxidized H2S were shifted to anoxia, the cells produced H2S evidently by re-using the oxidized sulfur. After aerobic H2S oxidation was stopped, the oxidation product remained available for H2S production for about 10 min. The observed H2S production is consistent with an evolutionary relationship of nucleocytoplasm to sulfur-reducing Archaea. Mitochondria often are the cellular site of H2S oxidation, suggesting that eukaryotic cells might have evolved from an ancient symbiosis that was based upon sulfur exchange.
Infraciliature of Opisthotrichum janus, Epidinium ecaudatum, and Ophryoscolex purkynjei (Ciliophora, Entodiniomorphida)
European Journal of Protistology, Volume 62, 2018, pp. 1-10
We described the infraciliature of Opisthotrichum janus, Epidinium ecaudatum, and Ophryoscolex purkynjei, belonging to the family Ophryoscolecidae, from pyridinated silver carbonate impregnated specimens. The adoral polybrachykinety is C-shaped in Opi. janus, whereas it is spiral-shaped in Epi. ecaudatum and Oph. purkynjei. The vestibular polybrachykinety is slender and short in Opi. janus, whereas slender and long in Epi. ecaudatum and Oph. purkynjei. The paralabial kineties are composed of several short kineties along the adoral polybrachykinety. The dorsal polybrachykinety is displaced posteriorly. This study provides information on the diagnostic features of the subfamily Ophryoscolecinae to which Opi. janus, Epi. ecaudatum, and Oph. purkynjei belong. A C-shaped or spiral-shaped adoral polybrachykinety and slender vestibular polybrachykinety are the diagnostic features of the subfamily Ophryoscolecinae in addition to their general features of a cylindrical body, tubular vestibulum, dorsal ciliary zone considerably displaced posteriorly, well developed skeletal plates, and macronucleus beneath the right body surface. Opi. janus, Epi. ecaudatum, and Oph. purkynjei show the basic form of morphogenesis of the ciliature, similar to that in the subfamily Diplodiniinae, with four primordia developing into the oral and dorsal ciliature.
Morphologic and molecular description of Metopus fuscus Kahl from North America and new rDNA sequences from seven metopids (Armophorea, Metopidae)
European Journal of Protistology, Volume 50, Issue 3, 2014, pp. 213-230
Most species in the large ciliate genus Metopus Claparède & Lachmann, 1858 lack detailed descriptions based on modern morphologic and molecular methods. This lack of data for the vast majority of species hampers application of a morphospecies approach to the taxonomy of Metopus and other armophorids. In this report we redescribe the large species, Metopus fuscus Kahl, 1927 based on in vivo observation, silver impregnation, scanning electron microscopy, and single-cell 18S rDNA sequencing of a freshwater North American (Idaho) population. Metopus fuscus invariably has a perinuclear envelope of endosymbiotic bacteria not found in other species. Unlike the original description of a single row of coarse granules between ciliary rows, the Idaho population has five loose rows of small interkinetal granules. We discuss the possible importance of this character in metopids. We also provide a phylogenetic analysis including seven other new metopid 18S rDNA sequences: Brachonella spiralis, B. galeata, Metopus laminarius, M. setosus, M. striatus, M. violaceus, Palmarella lata. Metopus fuscus and M. setosus form a fully supported clade, challenging previous morphospecies groupings. We discuss some ambiguities of armophorid morphologic terminology in the earlier literature. Our phylogenetic analysis of Idaho metopids indicates that the genera Metopus and Brachonella are both nonmonophyletic.
Morphologic and molecular characterization of seven species of the remarkably diverse and widely distributed metopid genus Urostomides Jankowski, 1964 (Armophorea, Ciliophora)
European Journal of Protistology, Volume 61, Part A, 2017, pp. 194-232
The free-living ciliates of the order Metopida Jankowski, 1980 are pivotal players in the microbial food web of the sulfuretum, acting as hosts to prokaryotic endo- and ectosymbionts. They are also of interest in the study of the function and evolution of their mitochondrion-related organelle, the hydrogenosome. The taxonomy and phylogeny of this group remains confused, due, in large part, to the fact that most of its taxa have not been characterized by modern methods including molecular sequencing. In this report we provide morphologic and molecular characterization of seven taxa from the poorly-known resurrected genus Urostomides obtained in the course of broad geographic sampling. Foissner (2016) established the family Apometopidae to include Apometopus (a junior synonym of Urostomides) and Cirranter Jankowski, 1964. These two genera differ from all other metopid genera in having a four-rowed perizonal ciliary stripe, the only currently recognizable morphologic synapomorphy for the family. The members of Urostomides show remarkable morphologic diversity. The genus has a broad geographic distribution, occurring on six continents. Urostomides species form a strongly supported clade in phylogenetic analyses. Relationships within the genus itself are less clearly resolved. The diagnoses of Apometopidae and Urostomides are emended.
Redescription and molecular phylogeny of the type species for two main metopid genera, Metopus es (Müller, 1776) Lauterborn, 1916 and Brachonella contorta (Levander, 1894) Jankowski, 1964 (Metopida, Ciliophora), based on broad geographic sampling
European Journal of Protistology, Volume 59, 2017, pp. 133-154
Metopid ciliates occupy terrestrial, freshwater, and marine habitats worldwide, playing important roles as predominant consumers of bacteria, flagellates, algae, and diatoms in hypoxic environments. Metopus and Brachonella are the most species-rich metopid genera, however most of their species have not been studied by modern methods Here, we report the morphologic, morphometric and molecular characterization, and phylogeny of Metopus es and Brachonella contorta, both types of their respective genera, collected in a broad global sampling effort. Five strains of M. es and three strains of B. contorta were studied in detail, providing the first correlation of morphology, morphometrics, and 18S rRNA gene sequencing for both. We submitted 29 new 18S rRNA gene sequences to GenBank. Phylogenetic analyses yielded trees of similar topology. A strongly supported Metopus es clade is sister to the Brachonella contorta clade. Our analysis shows genus Metopus is not monophyletic. The monophyly of Brachonella cannot yet be determined due to lack of sequences for other species of this genus in molecular databases. Both species appear to have a global distribution. Metopus es was not found in Africa, probably reflecting low sampling effort. Strains of both species showed low 18S rRNA gene sequence divergence despite wide geographic separation.
Morphology, morphogenesis, and phylogeny of an Anteholosticha intermedia (Ciliophora, Urostylida) population from the United States
European Journal of Protistology, Volume 65, 2018, pp. 1-15
A distinct population of Anteholosticha intermedia was isolated from soil in the Great Smoky Mountains of North Carolina, USA, and its morphology, morphogenesis and molecular phylogeny investigated by microscopic observations of live and protargol-prepared specimens and analyses of the sequence of small subunit (SSU) rDNA. Our population closely resembles the populations from Austria and Korea. Members of the genus Anteholosticha have been regarded as ontogenetically diverse, which is confirmed by the present work. The most noteworthy ontogenetic feature of the American population of A. intermedia is that the oral primordium in the proter appears apokinetally at the posterior end of the undulating membranes anlage at the beginning of division and then dedifferentiates midway through morphogenesis. Molecular phylogenetic analyses demonstrate, with high support, that the American population of A. intermedia is clearly distinct from congeners and branches as part of a sister lineage to the Bakuella–Urostyla clade that belongs to the major clade comprising the order Urostylida.
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