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Marine Life Science & Technology Aug 2023During a study on the diversity of ciliated protists in Lake Weishan Wetland, the largest wetland in northern China, four epibiotic sessilid peritrichs were isolated...
On four epibiotic peritrichous ciliates (Protozoa, Ciliophora) found in Lake Weishan Wetland: morphological and molecular data support the establishment of a new genus, gen. nov., and two new species.
During a study on the diversity of ciliated protists in Lake Weishan Wetland, the largest wetland in northern China, four epibiotic sessilid peritrichs were isolated from aquatic host animals. Two of them, i.e., Kellicott, 1885 and Fauré-Fremiet, 1943, were known species whereas the other two, i.e., gen. nov., sp. nov. and sp. nov., are new to science. The new genus gen. nov. is characterized by its branched non-contractile stalk, everted peristomial lip, obconical macronucleus and transverse silverlines. Two species are assigned to the new genus, namely sp. nov. and (Fauré-Fremiet, 1905) comb. nov. Morphologically, sp. nov. is recognized by its goblet-shaped zooids, single-layered peristomial lip, dichotomously branched stalk, and infundibular polykinety 3 (P3) containing three equal-length rows. sp. nov. is characterized by its slender zooid, curved macronucleus, and three equal-length rows in infundibular P3. Improved diagnoses and redescriptions of and are provided including, for the first time, data on the ciliature of . Phylogenetic analyses based on SSU rDNA, ITS1-5.8S rDNA -ITS2, and LSU rDNA sequence data strongly support the assertion that the family Epistylididae comprises morphospecies with different evolutionary lineages and indicate that gen. nov. may represent a new taxon at family level.
PubMed: 37637257
DOI: 10.1007/s42995-023-00184-z -
Journal of Indian Society of... 2023Periodontitis characterized by mild symptoms in the early stages, which makes diagnostics problematic. The gingival epithelium can be used for micronucleus assay since...
CONTEXT
Periodontitis characterized by mild symptoms in the early stages, which makes diagnostics problematic. The gingival epithelium can be used for micronucleus assay since gums are the area affected by the disease.
AIMS
The aim of the study was to study the frequency of occurrence and the range of nuclear anomalies in gingival epithelium of healthy people and people with periodontitis.
SETTINGS AND DESIGN
Scrapings of the gingival epithelium were made next to the central incisors (1.1) and molar teeth (1.7) in control and experimental groups (ten healthy males 35-50 years old and 10 males with periodontitis).
MATERIALS AND METHODS
The preparations were stained by Romanowsky-Giemsa. The frequency of nuclear aberrations (‰), the accumulation index, and the repair index were determined.
STATISTICAL ANALYSIS USED
The differences in the medians of nuclear aberrations were determined using Wilcoxon and the Van-der-Waerden tests. The pathology proportions were compared using the -test. To determine the predictors of periodontitis, receiver operator characteristic analysis was used. For multiple comparisons, the Bonferroni correction was used.
RESULTS
In the experimental group, the range of nuclear aberrations was wider, the ratio of karyolysis in the unaffected area was higher, than that in control; perinuclear vacuoles were fewer and macronuclei were more in the affected area. The frequency of cells with micronuclei over 1.33‰ in the affected area is the periodontitis marker.
CONCLUSIONS
Gingival epithelium can be used in micronucleus assay. Micronucleus test revealed a wider range of nuclear aberrations in the cells of the gingival epithelium and a higher frequency of occurrence of micronuclei in patients with periodontal disease compared to healthy subjects. Therefore, cytological signs of the inflammation appear earlier than the clinical ones and are verified more clearly. The markers of apoptosis and destruction of nuclei, and low repair index indicate normal elimination of damaged cells. An increased accumulation index in people with periodontitis may indicate the risk of malignant tumors.
PubMed: 37593557
DOI: 10.4103/jisp.jisp_18_22 -
IScience Aug 2023provides a unique opportunity to study how cells regulate nuclear shape because its macronucleus undergoes a rapid, dramatic, and developmentally regulated shape...
provides a unique opportunity to study how cells regulate nuclear shape because its macronucleus undergoes a rapid, dramatic, and developmentally regulated shape change. We found that the volume of the macronucleus increases during coalescence, suggesting an inflation-based mechanism. When the nuclear transport factor, CSE1, is knocked down by RNAi, the shape and volume changes of the macronucleus are attenuated, and nuclear morphology is altered. CSE1 protein undergoes a dynamic relocalization correlated with nuclear shape changes, being mainly cytoplasmic prior to nuclear coalescence, and accumulating inside the macronucleus during coalescence. At the end of regeneration, CSE1 protein levels are reduced as the macronucleus returns to its pre-coalescence volume. We propose a model in which nuclear transport via CSE1 is required to increase the volume of the macronucleus, thereby decreasing the surface-to-volume ratio and driving coalescence of the nodes into a single mass.
PubMed: 37520736
DOI: 10.1016/j.isci.2023.107318 -
International Journal of Molecular... Jun 2023Mismatch repair (MMR) is a conserved mechanism that is primarily responsible for the repair of DNA mismatches during DNA replication. Msh2 forms MutS heterodimer...
Mismatch repair (MMR) is a conserved mechanism that is primarily responsible for the repair of DNA mismatches during DNA replication. Msh2 forms MutS heterodimer complexes that initiate the MMR in eukaryotes. The function of Msh2 is less clear under different chromatin structures. contains a transcriptionally active macronucleus (MAC) and a transcriptionally silent micronucleus (MIC) in the same cytoplasm. Msh2 is localized in the MAC and MIC during vegetative growth. Msh2 is localized in the perinuclear region around the MIC and forms a spindle-like structure as the MIC divides. During the early conjugation stage, Msh2 is localized in the MIC and disappears from the parental MAC. Msh2 is localized in the new MAC and new MIC during the late conjugation stage. Msh2 also forms a spindle-like structure with a meiotic MIC and mitotic gametic nucleus. knockdown inhibits the division of MAC and MIC during vegetative growth and affects cellular proliferation. knockdown mutants are sensitive to cisplatin treatment. knockdown also affects micronuclear meiosis and gametogenesis during sexual development. Furthermore, Msh2 interacts with MMR-dependent and MMR-independent factors. Therefore, Msh2 is necessary for macronuclear stability, as well as micronuclear mitosis and meiosis in .
Topics: Tetrahymena thermophila; MutS Homolog 2 Protein; DNA Mismatch Repair; Cell Nucleus; Macronucleus
PubMed: 37445734
DOI: 10.3390/ijms241310559 -
Microorganisms May 2023The genus Dujardin, 1841, with nearly 40 morphospecies, is one of the largest genera in the well-known subclass Scuticociliatia. In the present study, two species were...
Taxonomic and Phylogenetic Studies of Two Brackish Species (Protista, Ciliophora, Scuticociliatia) from Subtropical Coastal Waters of China, with Report of a New Species.
The genus Dujardin, 1841, with nearly 40 morphospecies, is one of the largest genera in the well-known subclass Scuticociliatia. In the present study, two species were collected from subtropical coastal waters of the East China Sea. The morphology and molecular phylogeny were investigated using modern standard methods. n. sp. is mainly characterized by an elliptical body in outline with the right ventrolateral side straight, 16-22 somatic kineties, 3-5 preoral kineties, and the posterior end of the membranelle 2a hook-like. An improved diagnosis of Pan et al., 2015 was provided: body size in vivo usually 90-135 × 45-85 μm, right ventrolateral side convex, 36-51 somatic kineties, 1-5 preoral kineties, one to three spherical macronuclei, membranelle 2a arranged in a zig-zag pattern in middle portion, posterior region hook-like, both membranelle 1 and membranelle 3 composed of three rows of basal bodies. The small subunit ribosomal DNA (SSU rDNA) of two species is sequenced, and their molecular phylogeny is analyzed. The new species n. sp. clusters with KF840519, JX310015, KF206430, and cf. KF848875, basically in accord with the morphological characteristics.
PubMed: 37374924
DOI: 10.3390/microorganisms11061422 -
European Journal of Protistology Aug 2023Two already known representatives of Holospora-like bacteria, "Candidatus Gortzia yakutica" from Paramecium putrinum and Preeria caryophila, originally retrieved from...
Two already known representatives of Holospora-like bacteria, "Candidatus Gortzia yakutica" from Paramecium putrinum and Preeria caryophila, originally retrieved from the Paramecium aurelia complex, were found in new hosts: Paramecium nephridiatum and Paramecium polycaryum, respectively. In the present study, these bacteria were investigated using morphological and molecular methods. For "Ca. G. yakutica", the first details of the electron microscopic structure in the main and new hosts were provided. Regarding Pr. caryophila, the ultrastructural description of this species was implemented by several features previously unknown, such as the so called "membrane cluster" dividing periplasm from cytoplasm and fine composition of infectious forms before and during its releasing from the infected macronucleus. The new combinations of these Holospora-like bacteria with ciliate hosts were discussed from biogeographical and ecological points of view. Host specificity of symbionts as a general paradigm was critically reviewed as well.
Topics: Holosporaceae; Symbiosis; Bacteria; Macronucleus; Paramecium; Phylogeny
PubMed: 37356197
DOI: 10.1016/j.ejop.2023.125998 -
Marine Life Science & Technology Nov 2022Ciliated protists are one of the most diverse and highly differentiated group among unicellular organisms. Doublets occur in ciliates when two cells fuse into a single...
Ciliated protists are one of the most diverse and highly differentiated group among unicellular organisms. Doublets occur in ciliates when two cells fuse into a single individual. Doublets contain two major cellular components (either cell in a doublet) and have traditionally been considered as developmental anomalies. Nevertheless, doublets can divide or even conjugate effectively, which may represent dispersal forms of the life stages. In addition, morphogenesis, as an important process in the life cycle, will provide important insights into the complex differentiation mechanism and various physiological phenomena. However, morphogenetic studies focusing on doublets of ciliates are very limited, which has become an obstacle to understand their complete life history. Here we isolated a doublet strain from the marine species (Müller, 1786) Diesing, 1850 and investigated its morphogenetic events during asexual reproduction. Our results indicate that: (1) the opisthe's oral primordium develops de novo beneath the cortex; (2) the frontoventral and transverse cirral anlagen, cirrus I/1, and marginal anlagen in both dividers develop de novo separately; (3) the dorsal kinety anlagen, the three rightmost ones of which produce three caudal cirri for the proter, occur within the parental structures in the mid-body region; (4) the opisthe acquires two caudal cirri, one from the end of each two rightmost kineties; and (5) there are two macronuclei and one micronucleus in the doublet and they divide amitotically and mitotically, respectively. Finally, we speculate that this special differentiation may be an adaptive form to adverse environments.
PubMed: 37078083
DOI: 10.1007/s42995-022-00150-1 -
Marine Life Science & Technology Aug 2022Ciliated protists are ideal material for studying the origin and evolution of sex, because of their nuclear dimorphism (containing both germline micronucleus and somatic...
Ciliated protists are ideal material for studying the origin and evolution of sex, because of their nuclear dimorphism (containing both germline micronucleus and somatic macronucleus in the same cytoplasm), special sexual processes (conjugation and autogamy), and high diversity of mating-type systems. However, the study of sexual process is limited to only a few species, due to the difficulties in inducing or observing conjugation. In the present study, we investigate the conjugation process in : (1) of the three prezygotic divisions, all micronuclei undergo the first two divisions (meiosis I, II), while a variable number of nuclei undergo the third division (mitosis); (2) the synkaryon divides three times after fertilization, giving rise to eight products that differentiate into four macronuclear anlagen and four micronuclei; (3) cells restore the vegetative stage after two successive cell fissions during which the macronuclear anlagen are distributed into daughter cells without division, while micronuclei divide mitotically; (4) the parental macronucleus begins to fragment following the first meiotic division and finally degenerates completely; (5) the entire process takes about 110 h, of which about 85 h are required for macronuclear development. In addition, we describe for the first time the process of genomic exclusion occurring between amicronucleate and micronucleate cells of , during which the micronucleate cell contributes a pronucleus to the amicronucleate cell, resulting in both exconjugants being homozygotes. These results provide new insights into the diversity of sexual processes and lay an important cytological basis for future in-depth studies of mating systems in ciliates.
PubMed: 37073165
DOI: 10.1007/s42995-022-00137-y -
Parasites & Vectors Mar 2023Chilodonella uncinata is an aerobic ciliate capable of switching between being free-living and parasitic on fish fins and gills, causing tissue damage and host...
BACKGROUND
Chilodonella uncinata is an aerobic ciliate capable of switching between being free-living and parasitic on fish fins and gills, causing tissue damage and host mortality. It is widely used as a model organism for genetic studies, but its mitochondrial metabolism has never been studied. Therefore, we aimed to describe the morphological features and metabolic characteristics of its mitochondria.
METHODS
Fluorescence staining and transmission electron microscopy (TEM) were used to observe the morphology of mitochondria. Single-cell transcriptome data of C. uncinata were annotated by the Clusters of Orthologous Genes (COG) database. Meanwhile, the metabolic pathways were constructed based on the transcriptomes. The phylogenetic analysis was also made based on the sequenced cytochrome c oxidase subunit 1 (COX1) gene.
RESULTS
Mitochondria were stained red using Mito-tracker Red staining and were stained slightly blue by DAPI dye. The cristae and double membrane structures of the mitochondria were observed by TEM. Besides, many lipid droplets were evenly distributed around the macronucleus. A total of 2594 unigenes were assigned to 23 functional classifications of COG. Mitochondrial metabolic pathways were depicted. The mitochondria contained enzymes for the complete tricarboxylic acid (TCA) cycle, fatty acid metabolism, amino acid metabolism, and cytochrome-based electron transport chain (ETC), but only partial enzymes involved in the iron-sulfur clusters (ISCs).
CONCLUSIONS
Our results showed that C. uncinata possess typical mitochondria. Stored lipid droplets inside mitochondria may be the energy storage of C. uncinata that helps its transmission from a free-living to a parasitic lifestyle. These findings also have improved our knowledge of the mitochondrial metabolism of C. uncinata and increased the volume of molecular data for future studies of this facultative parasite.
Topics: Animals; Alveolata; Parasites; Phylogeny; Ciliophora; Mitochondria
PubMed: 36882771
DOI: 10.1186/s13071-023-05695-3 -
Microorganisms Feb 2023Locus-specific gene amplification and genome-wide endoreplication generate the elevated copy number of ribosomal DNA (rDNA, 9000 C) and non-rDNA (90 C) chromosomes in...
Locus-specific gene amplification and genome-wide endoreplication generate the elevated copy number of ribosomal DNA (rDNA, 9000 C) and non-rDNA (90 C) chromosomes in the developing macronucleus of . Subsequently, all macronuclear chromosomes replicate once per cell cycle during vegetative growth. Here, we describe an unanticipated, programmed switch in the regulation of replication initiation in the rDNA minichromosome. Early in development, the 21 kb rDNA minichromosome is preferentially amplified from 2 C to ~800 C from well-defined origins, concurrent with genome-wide endoreplication (2 C to 8-16 C) in starved mating (endoreplication (ER) Phase 1). Upon refeeding, rDNA and non-rDNA chromosomes achieve their final copy number through resumption of just the endoreplication program (ER Phase 2). Unconventional rDNA replication intermediates are generated primarily during ER phase 2, consistent with delocalized replication initiation and possible formation of persistent RNA-DNA hybrids. Origin usage and replication fork elongation are affected in non-rDNA chromosomes as well. Despite the developmentally programmed 10-fold reduction in the ubiquitous eukaryotic initiator, the Origin Recognition Complex (ORC), active initiation sites are more closely spaced in ER phases 1 and 2 compared to vegetative growing cells. We propose that initiation site selection is relaxed in endoreplicating macronuclear chromosomes and may be less dependent on ORC.
PubMed: 36838456
DOI: 10.3390/microorganisms11020491