Basic bioinformatical analysis of the draft Euplotes crassus macronuclear genome and transcriptome suggests that more than a quarter of E. crassus genes contain several exons. A large fraction of all introns is formed by "tiny" introns having length 20-30 bp. Analysis of the transcriptome revealed 63 possible cases of alternative splicing, and also 14 introns with non-standard splicing sites. About 2000 hypothetical genes do not have homologs in other ciliates, and since most of them have the closest homologs in bacterial genomes, they are likely an artifact of the sample preparation. Comparison of the E. crassus genome to the genomes of other ciliates showed an expansion of the same gene families, responsible for the free-living heterotrophic lifestyle.
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Nucleic Acids Res
December 2024
MOE Key Laboratory of Evolution & Marine Biodiversity and Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China.
The ciliate Tetrahymena thermophila is a well-established unicellular model eukaryote, contributing significantly to foundational biological discoveries. Despite its acknowledged importance, current studies on Tetrahymena biology face challenges due to gene annotation inaccuracy, particularly the notable absence of untranslated regions (UTRs). To comprehensively annotate the Tetrahymena macronuclear genome, we collected extensive transcriptomic data spanning various cell stages.
View Article and Find Full Text PDFFront Biosci (Landmark Ed)
November 2024
Department of Cancer Cell Biology, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia.
Background: In the twentieth century, the textbook idea of packaging genomic material in the cell nucleus and metaphase chromosomes was the presence of a hierarchy of structural levels of chromatin organization: nucleosomes - nucleosomal fibrils -30 nm fibrils - chromomeres - chromonemata - mitotic chromosomes. Chromomeres were observed in partially decondensed chromosomes and interphase chromatin as ~100 nm globular structures. They were thought to consist of loops of chromatin fibres attached at their bases to a central protein core.
View Article and Find Full Text PDFBMC Biol
October 2024
Laboratory of Marine Protozoan Biodiversity and Evolution, Marine College, Shandong University, Weihai, 264209, China.
Background: As a potential model organism for studies of environmental and cell biology, Paramecium duboscqui is a special euryhaline species of Paramecium that can be found in fresh, brackish, or marine water in natural salinity ranges between 0‰ and 33‰. However, the genome information as well as molecular mechanisms that account for its remarkable halotolerant traits remain extremely unknown. To characterize its genome feature, we combined PacBio and Illumina sequencing to assemble the first high-quality and near-complete macronuclear genome of P.
View Article and Find Full Text PDFISME J
January 2024
Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, Shandong 266003, China.
Microb Genom
July 2024
Laboratório de Diversidade Genética, Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
Several hundred ciliate species live in animals' guts as a part of their microbiome. Among them, (Trichostomatia, Pycnotrichidae), the largest described ciliate, is found exclusively associated with (capybara), the largest known rodent reaching up to 90 kg. Here, we present the sequence, structural and functional annotation of this giant microeukaryote macronuclear genome and discuss its phylogenetic placement.
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