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International Journal of Systematic and... Jan 2021Two new species have been isolated from cold shallow sandy sediments of the extreme Southern Chilean coasts: sp. nov., from a low-salinity site at Puerto Natales on...
Two new species of with cirrotype-9, sp. nov. and sp. nov. (Ciliophora, Spirotrichea, Euplotida), from the coasts of Patagonia: implications from their distant, early and late branching in the phylogenetic tree.
Two new species have been isolated from cold shallow sandy sediments of the extreme Southern Chilean coasts: sp. nov., from a low-salinity site at Puerto Natales on the Pacific coast, and sp. nov., from a marine site at Punta Arenas on the Atlantic coast. has a medium body size (53×36 µm ), 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. has a small body size (39×27 µm ), 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 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 Borror and Hill, 1995. Phylogenetic analyses of small subunit rRNA gene sequences, however, classify into its own early branching clade and into a late branching clade. This indicates a polyphyletic nature and taxonomic inconsistency of the genus , which was erected to include species with cirrotype-9 pattern I.
Topics: Base Composition; Chile; DNA, Protozoan; Euplotes; Genes, rRNA; Geologic Sediments; Phylogeny; Salinity; Sequence Analysis, DNA
PubMed: 33201796
DOI: 10.1099/ijsem.0.004568 -
Cell Reports Apr 2024In the ciliate Paramecium, precise excision of numerous internal eliminated sequences (IESs) from the somatic genome is essential at each sexual cycle. DNA...
In the ciliate Paramecium, precise excision of numerous internal eliminated sequences (IESs) from the somatic genome is essential at each sexual cycle. DNA double-strands breaks (DSBs) introduced by the PiggyMac endonuclease are repaired in a highly concerted manner by the non-homologous end joining (NHEJ) pathway, illustrated by complete inhibition of DNA cleavage when Ku70/80 proteins are missing. We show that expression of a DNA-binding-deficient Ku70 mutant (Ku70-6E) permits DNA cleavage but leads to the accumulation of unrepaired DSBs. We uncoupled DNA cleavage and repair by co-expressing wild-type and mutant Ku70. High-throughput sequencing of the developing macronucleus genome in these conditions identifies the presence of extremities healed by de novo telomere addition and numerous translocations between IES-flanking sequences. Coupling the two steps of IES excision ensures that both extremities are held together throughout the process, suggesting that DSB repair proteins are essential for assembly of a synaptic precleavage complex.
Topics: Paramecium; DNA Cleavage; DNA Breaks, Double-Stranded; Genome, Protozoan; Ku Autoantigen; DNA Repair; Protozoan Proteins; DNA End-Joining Repair
PubMed: 38547127
DOI: 10.1016/j.celrep.2024.114001 -
Genomics May 2021Entodinium caudatum is an anaerobic binucleated ciliate representing the most dominant protozoal species in the rumen. However, its biological features are largely...
Entodinium caudatum is an anaerobic binucleated ciliate representing the most dominant protozoal species in the rumen. However, its biological features are largely unknown due to the inability to establish an axenic culture. In this study, we primally sequenced its macronucleus (MAC) genome to aid the understanding of its metabolism, physiology, ecology. We isolated the MAC of E. caudatum strain MZG-1 and sequenced the MAC genome using Illumina MiSeq, MinION, and PacBio RSII systems. De novo assembly of the MiSeq sequence reads followed with subsequent scaffolding with MinION and PacBio reads resulted in a draft MAC genome about 117 Mbp. A large number of carbohydrate-active enzymes were likely acquired through horizontal gene transfer. About 8.74% of the E. caudatum predicted proteome was predicted as proteases. The MAC genome of E. caudatum will help better understand its important roles in rumen carbohydrate metabolism, and interaction with other members of the rumen microbiome.
Topics: Anaerobiosis; Animals; Carbohydrate Metabolism; Ciliophora; Rumen; Sequence Analysis, DNA
PubMed: 33722656
DOI: 10.1016/j.ygeno.2021.03.014 -
Journal of Fish Diseases Mar 2023Cryptocaryon irritans causes one of the most serious diseases in various wild and cultured marine fish, leading to mass mortality and economic loss. In this study,...
Cryptocaryon irritans causes one of the most serious diseases in various wild and cultured marine fish, leading to mass mortality and economic loss. In this study, hydroxyl radical (•OH) solution produced by strong ionization discharge combined with water jet cavitation effect was injected into orange-spotted grouper (Epinephelus coioides) aquaculture tanks for C. irritans control. The results showed that all C. irritans theronts were inactivated by •OH solution at concentrations of 0.5 mg/L within 2 min. •OH could induce alteration of shape, the absence of motility and macronucleus dispersion in theronts. A possible explanation was that the macronucleus of C. irritans might be damaged by •OH; as a result, its metabolism and life activities were disturbed. The •OH treatment increased the survival rate of E. coioides challenged with C. irritans from 64.7 ± 8.0% (mean ± SD) to 100% and reduced their infection intensity significantly. Stress response biomarkers such as malonaldehyde, glutathione, glutathione peroxidase, superoxide dismutase (SOD) and catalase levels in the gills of E. coioides at different time points were analysed. The SOD activity in the •OH group first decreased and then recovered to the initial level at the end of the experiment. The other stress response biomarkers had no significant difference from that in the uninfected control group after •OH treatment. Additionally, the gill of E. coioides in the •OH group exhibited slight and reversible transformation compared with the uninfected control group. Compared with •OH treatment, chlorine dioxide and formalin treatment reduced the survival rate, induced oxidative damage and changed the histological gill structure in E. coioides. In conclusion, •OH could be applied effectively to control C. irritans infection without affecting the normal physiological condition of E. coioides.
Topics: Animals; Bass; Ciliophora; Ciliophora Infections; Fish Diseases; Hymenostomatida; Superoxide Dismutase; Fish Proteins
PubMed: 36519440
DOI: 10.1111/jfd.13736 -
MBio Dec 2019Ciliates, a eukaryotic clade that is over 1 billion years old, are defined by division of genome function between transcriptionally inactive germline micronuclei and...
Ciliates, a eukaryotic clade that is over 1 billion years old, are defined by division of genome function between transcriptionally inactive germline micronuclei and functional somatic macronuclei. To date, most analyses of gene family evolution have been limited to cultivable model lineages (e.g., , , , and ). Here, we focus on the uncultivable Karyorelictea and its understudied sister class Heterotrichea, which represent two extremes in genome architecture. Somatic macronuclei within the Karyorelictea are described as nearly diploid, while the Heterotrichea have hyperpolyploid somatic genomes. Previous analyses indicate that genome architecture impacts ciliate gene family evolution as the most diverse and largest gene families are found in lineages with extensively processed somatic genomes (i.e., possessing thousands of gene-sized chromosomes). To further assess ciliate gene family evolution, we analyzed 43 single-cell transcriptomes from 33 ciliate species representing 10 classes. Focusing on conserved eukaryotic genes, we use estimates of transcript diversity as a proxy for the number of paralogs in gene families among four focal clades: Karyorelictea, Heterotrichea, extensive fragmenters (with gene-size somatic chromosomes), and non-extensive fragmenters (with more traditional somatic chromosomes), the latter two within the subphylum Intramacronucleata. Our results show that (i) the Karyorelictea have the lowest average transcript diversity, while Heterotrichea are highest among the four groups; (ii) proteins in Karyorelictea are under the highest functional constraints, and the patterns of selection in ciliates may reflect genome architecture; and (iii) stop codon reassignments vary among members of the Heterotrichea and Spirotrichea but are conserved in other classes. To further our understanding of genome evolution in eukaryotes, we assess the relationship between patterns of molecular evolution within gene families and variable genome structures found among ciliates. We combine single-cell transcriptomics with bioinformatic tools, focusing on understudied and uncultivable lineages selected from across the ciliate tree of life. Our analyses show that genome architecture correlates with patterns of protein evolution as lineages with more canonical somatic genomes, such as the class Karyorelictea, have more conserved patterns of molecular evolution compared to other classes. This study showcases the power of single-cell transcriptomics for investigating genome architecture and evolution in uncultivable microbial lineages and provides transcriptomic resources for further research on genome evolution.
Topics: Ciliophora; Computational Biology; Evolution, Molecular; Gene Expression Profiling; Genetic Variation; Genome, Protozoan; Multigene Family; Phylogeny; Single-Cell Analysis
PubMed: 31874915
DOI: 10.1128/mBio.02524-19 -
European Journal of Protistology Aug 2021The ciliated protist Tetrahymena thermophila is a well-known model organism with typical nuclear dimorphism containing a somatic macronucleus (MAC) and a germline...
The ciliated protist Tetrahymena thermophila is a well-known model organism with typical nuclear dimorphism containing a somatic macronucleus (MAC) and a germline micronucleus (MIC). The presence in the same cell compartment of two nuclei with distinctly different structural and functional properties provides an ideal model system to explore mechanisms of genome maintenance. Although methods for the isolation of MIC have been available for many years, cross-contamination and DNA degradation remain unresolved. Here, we describe a reliable and quick method to isolate MIC with high purity and DNA integrity in T. thermophila. Different factors are examined to optimize the MIC purification. The MAC contamination ratio in purified MIC is about 0.19% and DNA integrity of purified MIC is maintained. We also establish a more accurate method to detect the contamination rate of nuclei including microscopic observation and PCR detection. This study will facilitate further epigenetic research in Tetrahymena.
Topics: DNA, Protozoan; Epigenesis, Genetic; Epigenomics; Micronucleus, Germline; Tetrahymena thermophila
PubMed: 34062315
DOI: 10.1016/j.ejop.2021.125804 -
Genome Biology and Evolution Sep 2020Schmidingerella arcuata is an ecologically important tintinnid ciliate that has long served as a model species in plankton trophic ecology. We present a partial...
Schmidingerella arcuata is an ecologically important tintinnid ciliate that has long served as a model species in plankton trophic ecology. We present a partial micronuclear genome and macronuclear transcriptome resource for S. arcuata, acquired using single-cell techniques, and we report on pilot analyses including functional annotation and genome architecture. Our analysis shows major fragmentation, elimination, and scrambling in the micronuclear genome of S. arcuata. This work introduces a new nonmodel genome resource for the study of ciliate ecology and genomic biology and provides a detailed functional counterpart to ecological research on S. arcuata.
Topics: Ciliophora; Genome, Protozoan; Genomic Structural Variation; Transcriptome
PubMed: 32870974
DOI: 10.1093/gbe/evaa185 -
The Journal of Eukaryotic Microbiology Jul 2020Two new ciliate species, Clevelandella lynni sp. n. and Nyctotherus galerus sp. n., were discovered in the hindgut of wood-feeding panesthiine cockroaches. Their...
Two New Endozoic Ciliates, Clevelandella lynni sp. n. and Nyctotherus galerus sp. n., Isolated from the Hindgut of the Wood-feeding Cockroach Panesthia angustipennis (Illiger, 1801).
Two new ciliate species, Clevelandella lynni sp. n. and Nyctotherus galerus sp. n., were discovered in the hindgut of wood-feeding panesthiine cockroaches. Their morphology was studied using standard methods, and their phylogenetic positions within the order Clevelandellida were determined using the 18S rRNA gene sequences. Clevelandella lynni is characterized by a prominent peristomial projection, a notched left body margin, a tear-shaped to broadly ovoidal macronucleus, a karyophore attached to the right body margin, and by an adoral zone composed of on average 48 membranelles and extending about 51% of body length. The diagnostic features of N. galerus include a short posterior body projection, a spherical to broadly ellipsoidal macronucleus, a karyophore attached to the right and left body margins, refractile bodies densely packed anterior to the macronucleus, and an adoral zone composed of on average 57 membranelles and extending about 70% body length. The order Clevelandellida was consistently depicted as monophyletic in 18S rRNA gene phylogenies. Nyctotherus galerus was placed in the paraphyletic family Nyctotheridae, as sister taxon to all other Nyctotherus and Clevelandella species isolated from cockroaches. Clevelandella lynni fell in the monophyletic family Clevelandellidae, as sister taxon to C. panesthiae KC139718 but with very poor statistical support.
Topics: Animals; Body Size; Ciliophora; Cockroaches; DNA, Protozoan; DNA, Ribosomal; Digestive System; Phylogeny; RNA, Ribosomal, 18S; Sequence Analysis, DNA
PubMed: 32108982
DOI: 10.1111/jeu.12793 -
European Journal of Protistology Jun 2024When the ciliate Spirostomum ambiguum is transected into two pieces, both fragments regenerate and proliferate. In the anterior fragments, which have lost their...
When the ciliate Spirostomum ambiguum is transected into two pieces, both fragments regenerate and proliferate. In the anterior fragments, which have lost their contractile vacuoles due to transection, new contractile vacuoles were formed at their posterior ends in a few minutes. When the cells were cut into three pieces, new contractile vacuoles were formed in the anterior and middle fragments, both at their posterior ends. Thus, the anterior-posterior axis of S. ambiguum was maintained after transection. Morphological repair, including the formation of the contractile vacuole, was also observed when only the anteriormost portion was transected to cut out a small fragment that did not contain part of the macronucleus. Scanning electron microscopy was performed to observe changes in the shape of the cleavage surface of S. ambiguum during the wound healing process. Within minutes after cutting, the cut surface was covered with a cilia-free membrane, preventing leakage of cytoplasmic contents. The surface of the cut area then rounded with time and was covered with cilia, completing the repair of the cut area in about one day.
Topics: Microscopy, Electron, Scanning; Ciliophora; Regeneration
PubMed: 38593565
DOI: 10.1016/j.ejop.2024.126079 -
Nucleic Acids Research Dec 2023Multinucleate cells are found in many eukaryotes, but how multiple nuclei coordinate their functions is still poorly understood. In the cytoplasm of the ciliate...
Multinucleate cells are found in many eukaryotes, but how multiple nuclei coordinate their functions is still poorly understood. In the cytoplasm of the ciliate Paramecium tetraurelia, two micronuclei (MIC) serving sexual reproduction coexist with a somatic macronucleus (MAC) dedicated to gene expression. During sexual processes, the MAC is progressively destroyed while still ensuring transcription, and new MACs develop from copies of the zygotic MIC. Several gene clusters are successively induced and switched off before vegetative growth resumes. Concomitantly, programmed genome rearrangement (PGR) removes transposons and their relics from the new MACs. Development of the new MACs is controlled by the old MAC, since the latter expresses genes involved in PGR, including the PGM gene encoding the essential PiggyMac endonuclease that cleaves the ends of eliminated sequences. Using RNA deep sequencing and transcriptome analysis, we show that impairing PGR upregulates key known PGR genes, together with ∼600 other genes possibly also involved in PGR. Among these genes, 42% are no longer induced when no new MACs are formed, including 180 genes that are co-expressed with PGM under all tested conditions. We propose that bi-directional crosstalk between the two coexisting generations of MACs links gene expression to the progression of MAC development.
Topics: Gene Expression; Gene Rearrangement; Genome; Paramecium tetraurelia; Macronucleus
PubMed: 37953377
DOI: 10.1093/nar/gkad1006