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Weibo Song - One of the best experts on this subject based on the ideXlab platform.
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Taxonomy and SSU rDNA-based phylogeny of three new Euplotes species (Protozoa, Ciliophora) from China seas
Journal of King Saud University - Science, 2020Co-Authors: Chunyu Lian, Jiamei Jiang, Khaled A S Al-rasheid, Yuanyuan Wang, Weibo SongAbstract:Abstract As widely accepted, Euplotid ciliates, a unique mono-cellular organisms, play important roles in ecological, environmental, evolutionary and basic biological studies. We investigate the living morphology, infraciliature and silverline system of three new marine Euplotes found from China in this study: Euplotes bergeri n. sp., E. weissei n. sp. and E. shini n. sp. The new species Euplotes bergeri is characterized by its dominant adoral zone of membranelles, ten frontoventral cirri, three or four caudal cirri, 12–14 dorsal kineties with 14–20 dikinetids in the mid-dorsal row, and a dorsal silverline system of the double-eurystomus type. Euplotes weissei can be recognized by its tiny size, having two conspicuous dorsal grooves, nine frontoventral cirri, one marginal cirri, six or seven dorsal kineties, ca. 10 basal bodies in the mid-dorsal row and a mix single-double silverline system. Euplotes shini is a medium-sized form with the ciliary and silverline pattern of the well-known E. minuta but differs from the latter mainly in SSU rDNA gene sequences and usually different-sized marginal cirri. Phylogenetic analyses based on molecular data documented the systematic positions of those new taxa and support the validity of all three organism as distinct species.
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morphological and molecular redefinition of Euplotes platystoma dragesco dragesco kerneis 1986 and aspidisca lynceus muller 1773 ehrenberg 1859 with reconsideration of a well known Euplotes ciliate Euplotes harpa stein 1859 ciliophora euplotida
Journal of Eukaryotic Microbiology, 2018Co-Authors: Chunyu Lian, Xiaotian Luo, Xinpeng Fan, Jie Huang, William A. Bourland, Weibo SongAbstract:We documented the morphology, infraciliature, silverline system, and molecular data of two euplotid species isolated from China, including two populations of the poorly known Euplotes platystoma Dragesco & Dragesco-Kerneis, and the previously well described Aspidisca lynceus (Muller, ) Ehrenberg, 1830. Based on the information available, an improved diagnosis of Euplotes platystoma is given, including: a narrow adoral zone with 44-68 membranelles, 10 frontoventral, 5 transverse, 2 left marginal and 2 caudal cirri, 11-13 dorsal kineties with 17-25 dikinetids in the mid-dorsal row, and dorsal silverline system of the double-eurystomus type. The Chinese population of Aspidisca lynceus closely resembles previously described populations. Phylogenetic analyses inferred from SSU rDNA sequences show that E. platystoma is closely related with E. neapolitanus, and the internal position of A. lynceus within this genus is still not robust. A reconsideration of the "well-known" Euplotes harpa and a comparison of all SSU rDNA sequences of E. harpa in GenBank are provided. We speculate that the sequences available from GenBank under the name of E. harpa are very likely from misidentified materials, that is, the identity of the species currently associated with the SSU rDNA of this "well-known" form in molecular databases requires further confirmation.
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Morphological and Molecular Redefinition of Euplotes platystoma Dragesco & Dragesco-Kernéis, 1986 and Aspidisca lynceus (Müller,1773) Ehrenberg, 1859, with Reconsideration of a "Well-known" Euplotes Ciliate, Euplotes harpa Stein, 1859 (Ciliophora, Eu
The Journal of eukaryotic microbiology, 2018Co-Authors: Chunyu Lian, Xiaotian Luo, Xinpeng Fan, Jie Huang, William A. Bourland, Weibo SongAbstract:We documented the morphology, infraciliature, silverline system, and molecular data of two euplotid species isolated from China, including two populations of the poorly known Euplotes platystoma Dragesco & Dragesco-Kerneis, and the previously well described Aspidisca lynceus (Muller, ) Ehrenberg, 1830. Based on the information available, an improved diagnosis of Euplotes platystoma is given, including: a narrow adoral zone with 44-68 membranelles, 10 frontoventral, 5 transverse, 2 left marginal and 2 caudal cirri, 11-13 dorsal kineties with 17-25 dikinetids in the mid-dorsal row, and dorsal silverline system of the double-eurystomus type. The Chinese population of Aspidisca lynceus closely resembles previously described populations. Phylogenetic analyses inferred from SSU rDNA sequences show that E. platystoma is closely related with E. neapolitanus, and the internal position of A. lynceus within this genus is still not robust. A reconsideration of the "well-known" Euplotes harpa and a comparison of all SSU rDNA sequences of E. harpa in GenBank are provided. We speculate that the sequences available from GenBank under the name of E. harpa are very likely from misidentified materials, that is, the identity of the species currently associated with the SSU rDNA of this "well-known" form in molecular databases requires further confirmation.
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Table S1 from Species delimitation for the molecular taxonomy and ecology of a widely distributed microbial eukaryotes genus Euplotes (Alveolata, Ciliophora)
2018Co-Authors: Yan Zhao, Alan Warren, Weibo SongAbstract:Euplotes species analyzed in this study, and their reliability assessment based on rDNA sequences (Bold numbers were newly sequenced) and other integrated information
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morphology and ssu rrna gene based phylogeny of two marine Euplotes species e orientalis spec nov and e raikovi ciliophora euplotida
European Journal of Protistology, 2010Co-Authors: Jiamei Jiang, Qianqian Zhang, Alan Warren, Khaled A S Alrasheid, Weibo SongAbstract:Abstract The living morphology, infraciliature and silverline system of two small marine Euplotes species , E. orientalis spec. nov. and E. raikovi Agamaliev, 1966 , isolated from a sandy beach near Qingdao, China, were investigated. Euplotes orientalis is characterized by a combination of features including their small size (35-45 μm long), five or six conspicuous dorsal ridges, two cilia-free basal plaques, eight normal-sized frontoventral cirri (FVC), and a double- patella- I type of silverline system. Euplotes raikovi is redescribed based on a Chinese population and includes the first detailed description of its morphology in vivo . It can be recognized by having one highly reduced and seven normal-sized frontoventral cirri, a single marginal cirrus, and a double- patella- I type of silverline system. For both species the small subunit rRNA (SSU rRNA) gene sequence was determined. Phylogenetic analyses based on these data indicate that E . orientalis is most closely related to E. plicatum and E. bisulcatus , whereas E. raikovi clusters with its conspecific strains, close to E. nobilii and E. elegans .
Lawrence A. Klobutcher - One of the best experts on this subject based on the ideXlab platform.
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Position-dependent termination and widespread obligatory frameshifting in Euplotes translation
Nature structural & molecular biology, 2016Co-Authors: Alexei V. Lobanov, Stephen M. Heaphy, Anton A. Turanov, Maxim V. Gerashchenko, Sandra Pucciarelli, Raghul Rajan Devaraj, Fang Xie, Vladislav A. Petyuk, Richard D. Smith, Lawrence A. KlobutcherAbstract:Large-scale sequencing approaches reveal that the genetic code of Euplotes ciliates supports widespread ribosomal frameshifting at stop codons, and that additional mechanisms are required for efficient translation termination.
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sequencing of random Euplotes crassus macronuclear genes supports a high frequency of 1 translational frameshifting
Eukaryotic Cell, 2005Co-Authors: Lawrence A. KlobutcherAbstract:Programmed translational frameshifts have been identified in genes from a broad range of organisms, but typically only a very few genes in a given organism require a frameshift for expression. In contrast, a recent analysis of gene sequences available in GenBank from ciliates in the genus Euplotes indicated that >5% required one or more +1 translational frameshifts to produce their predicted protein products. However, this sample of genes was nonrandom, biased, and derived from multiple Euplotes species. To test whether there truly is an abundance of frameshift genes in Euplotes, and to more accurately assess their frequency, we sequenced a random sample of 25 cloned genes/macronuclear DNA molecules from Euplotes crassus. Three new candidate +1 frameshift genes were identified in the sample that encode a membrane occupation and recognition nexus (MORN) repeat protein, a C2H2-type zinc finger protein, and a Ser/Thr protein kinase. Reverse transcription-PCR analyses indicate that all three genes are expressed in vegetatively proliferating cells and that the mRNAs retain the requirement of a frameshift. Although the sample of sequenced genes is relatively small, the results indicate that the frequency of genes requiring frameshifts in E. crassus is between 3.7% and 31.7% (at a 95% confidence interval). The current and past data also indicate that frameshift sites are found predominantly in genes that likely encode nonabundant proteins in the cell.
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A high percentage of Euplotes genes require a +1 translational frameshift for expression
The Journal of Eukaryotic Microbiology, 2005Co-Authors: Lawrence A. Klobutcher, Matthias Möllenbeck, Michael C. Gavin, Philip J FarabaughAbstract:A previous survey of Euplotes genes available in GenBank indicated that >5% required a +1 translational frameshift for expression, much higher than observed in other organisms. Because this sample of sequences was non-random and biased towards highly expressed genes, we have randomly selected and sequenced 25 Euplotes crassus macronuclear DNA molecules to more accurately assess the frequency of frameshifting. Three new +1 frameshift genes were identified, and all have sequence features similar to the previously postulated frameshift sites. The results indicate that the frequency of Euplotes+1 frameshift genes is indeed high, and likely >10%. We have also examined the evolution of one of two frameshift sites present in the telomerase reverse transcriptase (TERT) genes of E. crassus. TERT gene segments were isolated from five additional Euplotes species. FS2 was found only in E. crassus and the closely related E. vannus, and phylogenetic analyses indicate that the site arose late in the evolution of the Euplotes group. Moreover, a novel frameshift site (FS3) was identified solely in the TERT gene of E. minuta. These results indicate that frameshift sites have arisen within genes during the recent history of Euplotes, and that it may be an ongoing process. Overall, the data suggest to us that the appearance of a frameshift site in a Euplotes gene is selectively neutral, or near-neutral. This would require an efficient mechanism of frameshifting in Euplotes. A model will be presented linking frequent frameshifting to a second unusual genetic feature of Euplotes, stop codon reassignment.
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Evolution of programmed ribosomal frameshifting in the TERT genes of Euplotes.
Journal of molecular evolution, 2004Co-Authors: Matthias Möllenbeck, Michael C. Gavin, Lawrence A. KlobutcherAbstract:A number of recent studies indicate that programmed +1 ribosomal frameshifting is frequently required for the expression of genes in species of the genus Euplotes. In E. crassus, three genes encoding the telomerase reverse transcriptase (TERT) subunit have been previously found to possess one or two +1 frameshift sites. To examine the origin of frameshift sites within the Euplotes group, we have isolated segments of the TERT gene from five Euplotes species. Coupled with phylogenetic analysis, the results indicate that one frameshift site in the TERT gene arose late in the evolution of the group. In addition, a novel frameshift site was identified in the TERT gene of E. minuta, a species where frameshifting has not been previously reported. Coupled with other studies, the results indicate that frameshift sites have arisen during the diversification of the euplotids. The results also are discussed in regard to the mutations necessary to generate frameshift sites, and the specialization of TERT protein function that has apparently occurred in E. crassus.
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characterization of transcription initiation translation initiation and poly a addition sites in the gene sized macronuclear dna molecules of Euplotes
Nucleic Acids Research, 1994Co-Authors: Susmita Ghosh, Lawrence A. Klobutcher, John W Jaraczewski, Carolyn L. JahnAbstract:The DNA in the transcriptionally active macronucleus of the hypotrichous ciliate Euplotes crassus exists as short, linear molecules with each molecule encoding a single genetic function. Previous work has indicated that coding regions occupy the majority of macronuclear DNA molecules. In the present study we have defined the transcription initiation sites and poly(A) addition sites for a number of different macronuclear genes in Euplotes crassus. Our results indicate that mature transcripts represent all but approximately 100-200 bases of the non-telomeric sequences in macronuclear DNA molecules. We have also examined the sequences in the vicinity of transcription start sites, poly(A) addition sites, and translation initiation sites for Euplotes species genes in an attempt to define the cis-acting elements that control these processes. Our results indicate that some of the common sequence elements known to control these processes in higher eukaryotes are likely not utilized by Euplotes genes. The data do indicate the presence of other conserved sequences both preceding and at the site of poly(A) addition, as well as at the site of translation initiation. These conserved sequences may serve an analogous role in these organisms. Finally, we have found that most macronuclear DNA molecules have transcription initiation sites within 30 bp of the telomere, suggesting that the telomere may play a role in promoting transcription.
Giulio Petroni - One of the best experts on this subject based on the ideXlab platform.
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Symbiont replacement between bacteria of different classes reveals additional layers of complexity in the evolution of symbiosis in the ciliate Euplotes.
Protist, 2017Co-Authors: Vittorio Boscaro, Sergei I. Fokin, Giulio Petroni, Franco Verni, Patrick J. Keeling, Claudia VanniniAbstract:Symbiosis is a diverse and complex phenomenon requiring diverse model systems. The obligate relationship between a monophyletic group of Euplotes species (“clade B”) and the betaproteobacteria Polynucleobacter and “Candidatus Protistobacter” is among the best-studied in ciliates, and provides a framework to investigate symbiont replacements. Several other Euplotes-bacteria relationships exist but are less understood, such as the co-dependent symbiosis between Euplotes magnicirratus (which belongs to “clade A”) and the alphaproteobacterium “Candidatus Devosia euplotis”. Here we describe a new Devosia inhabiting the cytoplasm of a strain of Euplotes harpa, a clade B species that usually depends on Polynucleobacter for survival. The novel bacterial species, “Candidatus Devosia symbiotica”, is closely related to the symbiont of E. magnicirratus, casting a different light on the history of bacteria colonizing ciliates of this genus. The two Devosia species may have become symbionts independently or as the result of a symbiont exchange between hosts, in either case replacing a previous essential bacterium in E. harpa. Alternatively, both may be remnants of an ancient symbiotic relationship between Euplotes and Devosia, in which case Polynucleobacter and “Ca. Protistobacter” are recent invaders. Either way, symbiont replacement between bacteria belonging to different classes must be evoked to explain this fascinating system.
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A new obligate bacterial symbiont colonizing the ciliate Euplotes in brackish and freshwater: ‘Candidatus Protistobacter heckmanni’
Aquatic Microbial Ecology, 2013Co-Authors: Claudia Vannini, Franco Verni, Filippo Ferrantini, Giulio PetroniAbstract:A monophyletic group of freshwater and brackish ciliate species belonging to the genus Euplotes is known to harbor bacterial endosymbionts of the class Betaproteobacteria permanently in the natural environment. One or other of 2 different species of bacteria have been shown to be present: the obligate symbiont Polynucleobacter necessarius or a recently described betaproteobacterium. While the association between P. necessarius and its Euplotes hosts has been well studied in the past, knowledge about the relationship between the newly discovered symbiont and its Euplotes hosts is still very poor. Here we present the SSUrRNA gene characterization of both host and symbiont for an additional brackish-water population of Euplotes hosting the newly discovered symbiont. We also provide the symbiont genome size determination and ultrastructural description. Attempts to cultivate the new symbiont outside its host, using many different methods, failed. This result indicates that, as in the case of the symbiotic P. necessarius, we are probably dealing with an obligate symbiont, unable to grow outside the cytoplasm of its natural host. On the basis of the results obtained we propose the new symbiont as a candidate new species with the name of ‘Candidatus Protistobacter heckmanni’, according to the current rules of prokaryotic nomenclature
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Betaproteobacterial symbionts of the ciliate Euplotes: origin and tangled evolutionary path of an obligate microbial association.
Environmental microbiology, 2012Co-Authors: Claudia Vannini, Franco Verni, Filippo Ferrantini, Alessandro Ristori, Giulio PetroniAbstract:Summary The Polynucleobacter–Euplotes association is an obligatory symbiotic system between a monophyletic group of ciliate species belonging to the genus Euplotes and bacteria of the species Polynucleobacter necessarius (Betaproteobacteria). Both organisms are unable to survive independently. Several studies revealed the existence of free-living populations of Polynucleobacter bacteria which are phylogenetically closely related to the endosymbiotic ones, but never share associations with Euplotes in the natural environment. Hence, following the most parsimonious explanation on the origin of the association, this symbiosis should represent a synapomorphic character for the hosts' clade. Nevertheless, phylogenetic analyses performed on an increased number of strains here presented suggest that Euplotes species, during their evolution, recruited Polynucleobacter bacteria as symbionts more than once. Moreover, in three cases, we observed different bacteria as obligate symbionts. These symbionts are the first characterized representatives of a phylogenetic lineage branching in a basal position with respect to the genus Polynucleobacter. The hypothesis that the original obligate symbionts belonged to this newly discovered clade and that, only subsequently, in most cases they have been replaced by Polynucleobacter bacteria recruited from the environment is proposed and discussed. The evolutionary path of this association seems anyway to have been more complex than so far supposed.
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Polynucleobacter bacteria in the brackish-water species Euplotes harpa (Ciliata Hypotrichia).
The Journal of eukaryotic microbiology, 2005Co-Authors: Claudia Vannini, Giulio Petroni, Franco Verni, Giovanna RosatiAbstract:We have found a Polynucleobacter bacterium in the cytoplasm of Euplotes harpa, a species living in a brackish-water habitat, with a cirral pattern not corresponding to that of the freshwater Euplotes species known to harbor this type of bacteria. The symbiont has been found in three strains of the species, obtained by clonal cultures from ciliates collected in different geographic regions. The 16S rRNA gene sequence of this bacterium identifies it as a member of the beta-proteobacterial genus Polynucleobacter. This sequence shares a high similarity value (98.4-98.5%) with P. necessarius, the type species of the genus, and is associated with 16S rRNA gene sequences of environmental clones and bacterial strains included in the Polynucleobacter cluster (>95%). An oligonucleotide probe was designed to corroborate the assignment of the retrieved sequence to the symbiont and to detect similar bacteria rapidly. Antibiotic experiments showed that the elimination of the bacteria stops the reproductive cycle in E. harpa, as has been shown for the freshwater Euplotes species.
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identification of the bacterial endosymbionts of the marine ciliate Euplotes magnicirratus ciliophora hypotrichia and proposal of candidatus devosia euplotis
International Journal of Systematic and Evolutionary Microbiology, 2004Co-Authors: Claudia Vannini, Franco Verni, Giovanna Rosati, Giulio PetroniAbstract:This paper reports the identification of bacterial endosymbionts that inhabit the cytoplasm of the marine ciliated protozoon Euplotes magnicirratus. Ultrastructural and full-cycle rRNA approaches were used to reveal the identity of these bacteria. Based on analysis of 16S rRNA gene sequences, evolutionary trees were constructed; these placed the endosymbiont in the genus Devosia in the α-Proteobacteria. The validity of this finding was also shown by fluorescence in situ hybridization with a Devosia-specific oligonucleotide probe. Differences at the 16S rRNA gene level (which allowed the construction of a species-specific oligonucleotide probe) and the peculiar habitat indicate that the endosymbiont represents a novel species. As its cultivation has not been successful to date, the provisional name ‘Candidatus Devosia euplotis' is proposed. The species- and group-specific probes designed in this study could represent convenient tools for the detection of ‘Candidatus Devosia euplotis' and Devosia-like bacteria in the environment.
Carolyn M. Price - One of the best experts on this subject based on the ideXlab platform.
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Origin Usage during Euplotes Ribosomal DNA Amplification
Eukaryotic cell, 2003Co-Authors: Ming Tan, Carolyn L. Jahn, Carolyn M. PriceAbstract:The macronuclear genome of the ciliate Euplotes is comprised of millions of small linear DNA molecules that have telomeres on each end. These molecules are generated during the sexual stage of the life cycle, when the new macronucleus is formed by a series of DNA processing events and multiple rounds of DNA amplification. We have used two-dimensional gels to compare the location of the replication origins used during vegetative growth and the two periods during macronuclear development when DNA amplification takes place. When we examined the pattern of ribosomal DNA (rDNA) replication intermediates, we observed almost identical Y arcs regardless of when in the Euplotes life cycle the DNA was isolated. No bubble or bubble-to-Y arcs could be detected. This indicates that replication of the macronuclear rDNA initiates at or near the telomere even when these molecules are being differentially amplified. Since replication rarely initiated from both ends of the rDNA, we examined the direction of replication fork movement to determine which end of the rDNA served as the origin. Fork movement gels indicated that replication initiated at the 5′ end. As transcription also starts near the telomere at the 5′ end, our findings suggest that the telomere and the promoter region cooperate to recruit Euplotes replication initiation complexes.
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Accumulation of telomerase RNA and telomere protein transcripts during telomere synthesis in Euplotes.
The Journal of eukaryotic microbiology, 1994Co-Authors: Carolyn M. Price, Angela K. Adams, Joris R. VermeeschAbstract:. In the ciliate Euplotes crassus a complex series of developmental events lead to formation of a new macronucleus. Millions of telomeres are synthesized during this process. We have shown that transcript levels are tightly regulated throughout Euplotes conjugation and macronuclear development. Thus, expression of gene products needed for macronuclear development and telomere synthesis appears to be controlled at the level of RNA abundance. To learn more about the role played by telomerase and the Euplotes telomere protein during telomere synthesis, we have correlated changes in the abundance of telomerase RNA and telomere protein mRNA transcript with specific developmental events. Telomerase RNA levels increase steadily during the early stages of macronuclear development and reach a peak just after telomere addition. The telomere protein transcript rises and falls twice during conjugation and then rises again at the time of telomere addition. The increases in transcript levels during conjugation parallel micronuclear division suggesting that the telomere protein is synthesized at this time and hence may have a micronuclear function.
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Telomere processing in Euplotes
Nucleic acids research, 1993Co-Authors: Joris R. Vermeesch, Dewight R. Williams, Carolyn M. PriceAbstract:In Euplotes crassus millions of telomeres are synthesized during the sexual phase of the life cycle. Since these newly synthesized telomeres are longer than normal macronuclear telomeres, they must be trimmed to the mature size. We have examined the timing and mechanism of this trimming step. We have shown that a sudden decrease in telomere length takes place at a specific time during macronuclear development. The decrease in telomere length is not caused by incomplete replication of the most terminal DNA sequences; rather it is the result of an active processing event that occurs independently of DNA replication. The developmentally regulated telomere shortening that takes place in Euplotes is reminiscent of the sudden reductions in telomere length which have been observed in other eukaryotes.
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Euplotes crassus has genes encoding telomere-binding proteins and telomere-binding protein homologs
Nucleic acids research, 1992Co-Authors: Wenlan Wang, Rose Skopp, Margaret A. Scofield, Carolyn M. PriceAbstract:Abstract We have identified two 1.6 kb macronuclear DNA molecules from Euplotes crassus that hybridize to the alpha subunit of the Oxytricha telomere protein. We have shown that one of these molecules encodes the 51 kDa Euplotes telomere protein while the other appears to encode a homolog of the telomere protein. Although this homolog clearly differs in sequence from the Euplotes telomere protein, the two proteins share extensive amino acid sequence identity with each other and with the alpha subunit of the Oxytricha telomere protein. In all three proteins 35-36% of the amino acids are identical, while 54-56% are similar. The most extended regions of sequence conservation map within the N-terminal section; this section has been shown to comprise the DNA-binding domain in the Euplotes telomere protein. Our findings suggest that some of the conserved amino acids may be involved in DNA recognition and binding. The gene encoding the telomere protein homolog contains two introns; one of these introns is only 24 bp in length. This is the smallest mRNA intron reported to date.
Pierangelo Luporini - One of the best experts on this subject based on the ideXlab platform.
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Two new species of Euplotes with cirrotype-9, Euplotes foissneri sp. nov. and Euplotes warreni sp. nov. (Ciliophora, Spirotrichea, Euplotida), from the coasts of Patagonia: implications from their distant, early and late branching in the Euplotes phy
International journal of systematic and evolutionary microbiology, 2020Co-Authors: Alessandro Valbonesi, Adriana Vallesi, Graziano Di Giuseppe, Pierangelo LuporiniAbstract:Two new Euplotes species have been isolated from cold shallow sandy sediments of the extreme Southern Chilean coasts: Euplotes foissneri sp. nov., from a low-salinity site at Puerto Natales on the Pacific coast, and Euplotes warreni sp. nov., from a marine site at Punta Arenas on the Atlantic coast. Euplotes foissneri has a medium body size (53×36 µm in vivo), a dorsal surface marked by six prominent ridges, a double dargyrome, six dorsal and two ventrolateral kineties, a buccal field extending to about 3/4 of the body length, an adoral zone composed of 28-32 membranelles, and nine fronto-ventral, five transverse and two or three caudal cirri. The bulky, hook-, horseshoe- or 3-shaped macronucleus is associated with one sub-spherical micronucleus. The central body region hosts taxonomically unidentified endosymbiotic eubacteria. Euplotes warreni has a small body size (39×27 µm in vivo), a smooth dorsal surface marked by three deep grooves, a double dargyrome, four dorsal and two ventrolateral kineties, a buccal field extending to about 2/3 of the body length, an adoral zone composed of 23-25 adoral membranelles, and nine fronto-ventral, five transverse and three caudal cirri. The macronucleus is hook- or C-shaped and associated with one spherical micronucleus. Endosymbiotic bacteria belonging to the genus Francisella reside preferentially in the anterior cell region. Both species lack the fronto-ventral cirrus numbered 'V/2', whereby their cirrotype-9 conforms to the so-called 'pattern I', which is the basic distinctive trait of the genus Euplotopsis Borror and Hill, 1995. Phylogenetic analyses of small subunit rRNA gene sequences, however, classify E. warreni into its own early branching clade and E. foissneri into a late branching clade. This indicates a polyphyletic nature and taxonomic inconsistency of the genus Euplotopsis, which was erected to include Euplotes species with cirrotype-9 pattern I.
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Molecular Structures and Coding Genes of the Water-Borne Protein Pheromones of Euplotes petzi, an Early Diverging Polar Species of Euplotes.
The Journal of eukaryotic microbiology, 2016Co-Authors: Bill Pedrini, Thea Suter-stahel, Adriana Vallesi, Claudio Alimenti, Pierangelo LuporiniAbstract:Euplotes is diversified into dozens of widely distributed species that produce structurally homologous families of water-borne protein pheromones governing self-/nonself-recognition phenomena. Structures of pheromones and pheromone coding genes have so far been studied from species lying in different positions of the Euplotes phylogenetic tree. We have now cloned the coding genes and determined the NMR molecular structure of four pheromones isolated from Euplotes petzi, a polar species which is phylogenetically distant from previously studied species and forms the deepest branching clade in the tree. The E. petzi pheromone genes have significantly shorter sequences than in other congeners, lack introns, and encode products of only 32 amino acids. Likewise, the three-dimensional structure of the E. petzi pheromones is markedly simpler than the three-helix up-down-up architecture previously determined in another polar species, Euplotes nobilii, and in a temperate-water species, Euplotes raikovi. Although sharing the same up-down-up architecture, it includes only two short α-helices that find their topological counterparts with the second and third helices of the E. raikovi and E. nobilii pheromones. The overall picture that emerges is that the evolution of Euplotes pheromones involves progressive increases in the gene sequence length and in the complexity of the three-dimensional molecular structure.
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improved description of the bipolar ciliate Euplotes petzi and definition of its basal position in the Euplotes phylogenetic tree
European Journal of Protistology, 2014Co-Authors: Graziano Di Giuseppe, Adriana Vallesi, Fabrizio Erra, Fernando Dini, Francesco Paolo Frontini, Pierangelo LuporiniAbstract:Abstract Data improving the characterization of the marine Euplotes species, E. petzi Wilbert and Song, 2008 , were obtained from morphological, ecological and genetic analyses of Antarctic and Arctic wild-type strains. This species is identified by a minute (mean size, 46 μm × 32 μm) and ellipsoidal cell body which is dorsally decorated with an argyrome of the double-patella type, five dorsal kineties (of which the median one contains 8–10 dikinetids), five sharp-edged longitudinal ridges, and a right anterior spur. Ventrally, it bears 10 fronto-ventral, five transverse, two caudal and two marginal cirri, 30–35 adoral membranelles, and three inconspicuous ridges. Euplotes petzi grows well at 4 °C on green algae, does not produce cysts, undergoes mating under the genetic control of a multiple mating-type system, constitutively secretes water-borne pheromones, and behaves as a psychrophilic microorganism unable to survive at >15 °C. While the α-tubulin gene sequence determination did not provide useful information on the E. petzi molecular phylogeny, the small subunit rRNA (SSU rRNA) gene sequence determination provided solid evidence that E. petzi clusters with E. sinicus Jiang et al., 2010a , into a clade which represents the deepest branch at the base of the Euplotes phylogentic tree.
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Thermodynamic Stability of Psychrophilic and Mesophilic Pheromones of the Protozoan Ciliate Euplotes
Biology, 2013Co-Authors: Michael Geralt, Adriana Vallesi, Claudio Alimenti, Pierangelo Luporini, Kurt WüthrichAbstract:Three psychrophilic protein pheromones (En-1, En-2 and En-6) from the polar ciliate, Euplotes nobilii, and six mesophilic pheromones (Er-1, Er-2, Er-10, Er-11, Er-22 and Er-23) from the temperate-water sister species, Euplotes raikovi, were studied in aqueous solution for their thermal unfolding and refolding based on the temperature dependence of their circular dichroism (CD) spectra. The three psychrophilic proteins showed thermal unfolding with mid points in the temperature range 55± 70 °C. In contrast, no unfolding was observed for any of the six mesophilic proteins and their regular secondary structures were maintained up to 95 °C. Possible causes of these differences are discussed based on comparisons of the NMR structures of the nine proteins.
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Euplotes bisulcatus, a key species for a better understanding of the organization and evolution of Euplotes argyrome patterns
European Journal of Protistology, 1995Co-Authors: Alessandro Valbonesi, Pierangelo LuporiniAbstract:Summary The structural organization of the dorsal cell surface was studied in parallel with the pattern of the dorsal argyrome in Euplotes bisulcatus and other related species of Euplotes . Evidence is provided for the involvement of cortical alveoli of similar width in the construction of double argyromes. Argyromes usually described as double- patella are shown to result from the presence of longitudinal ridges of varying shapes on the dorsal cell surface, which strongly affect the appearance of the argyrome under light microscopy. On a completely different experimental basis, this work supports the suggestion by Gates and Curds [5] that the typology of the dorsal argyrome of Euplotes should be restricted only to the basic types single, double, and multiple. In addition, it reiterates the diagnostic value of cortical sculpturing in Euplotes taxonomy.
