110 research outputs found

    Palliative Care for the Elderly:A Japanese Perspective

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    核による二次葉緑体の分裂制御機構の解明

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    科学研究費助成事業 研究成果報告書:若手研究(B)2015-2017課題番号 : 15K1858

    Software Log Anomaly Detection Through One Class Clustering of Transformer Encoder Representation

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    For smart devices such as smartphones and tablets, developing new software using open source software (OSS) is becoming mainstream. While OSS-based development can greatly increase project productivity, it is more difficult to identify the cause of software defects. In this paper, we propose a deep learning model that performs unsupervised learning based on the log data accumulated in the project and calculates the degree of abnormality per line for newly given logs. The proposed method is evaluated using open supercomputer system log data, Blue Gene/L, and the accuracy of the proposed method is compared with the conventional log anomaly detection method using LSTM AutoEncoder. As a result of the comparative experiment, it was found that the proposed method performed better than the conventional method in the two scores of AUROC and F1 Score at the cutoff point.22nd International Conference on Human-Computer Interaction, HCI International 2020, 19-24 July 2020, Copenhagen, Denmark(新型コロナ感染拡大に伴い、現地開催中止

    Organellar DNA Polymerases in Complex Plastid-Bearing Algae

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    DNA replication in plastids and mitochondria is generally regulated by nucleus-encoded proteins. In plants and red algae, a nucleus-encoded enzyme called POP (plant and protist organellar DNA polymerase) is involved in DNA replication in both organelles by virtue of its dual localization. POPs are family A DNA polymerases, which include bacterial DNA polymerase I (PolI). POP homologs have been found in a wide range of eukaryotes, including plants, algae, and non-photosynthetic protists. However, the phylogeny and subcellular localizations of POPs remain unclear in many algae, especially in secondary and tertiary plastid-bearing groups. In this study, we report that chlorarachniophytes possess two evolutionarily distinct POPs, and fluorescent protein-tagging experiments demonstrate that they are targeted to the secondary plastids and mitochondria, respectively. The timing of DNA replication is different between the two organelles in the chlorarachniophyte Bigelowiella natans, and this seems to be correlated to the transcription of respective POP genes. Dinoflagellates also carry two distinct POP genes, possibly for their plastids and mitochondria, whereas haptophytes and ochrophytes have only one. Therefore, unlike plants, some algal groups are likely to have evolved multiple DNA polymerases for various organelles. This study provides a new insight into the evolution of organellar DNA replication in complex plastid-bearing organisms

    Multiple losses of photosynthesis and convergent reductive genome evolution in the colourless green algae Prototheca

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    Autotrophic eukaryotes have evolved by the endosymbiotic uptake of photosynthetic organisms. Interestingly, many algae and plants have secondarily lost the photosynthetic activity despite its great advantages. Prototheca and Helicosporidium are non-photosynthetic green algae possessing colourless plastids. The plastid genomes of Prototheca wickerhamii and Helicosporidium sp. are highly reduced owing to the elimination of genes related to photosynthesis. To gain further insight into the reductive genome evolution during the shift from a photosynthetic to a heterotrophic lifestyle, we sequenced the plastid and nuclear genomes of two Prototheca species, P. cutis JCM 15793 and P. stagnora JCM 9641, and performed comparative genome analyses among trebouxiophytes. Our phylogenetic analyses using plastid- and nucleus-encoded proteins strongly suggest that independent losses of photosynthesis have occurred at least three times in the clade of Prototheca and Helicosporidium. Conserved gene content among these non-photosynthetic lineages suggests that the plastid and nuclear genomes have convergently eliminated a similar set of photosynthesis-related genes. Other than the photosynthetic genes, significant gene loss and gain were not observed in Prototheca compared to its closest photosynthetic relative Auxenochlorella. Although it remains unclear why loss of photosynthesis occurred in Prototheca, the mixotrophic capability of trebouxiophytes likely made it possible to eliminate photosynthesis

    Encyclopedia of Family A DNA Polymerases Localized in Organelles: Evolutionary Contribution of Bacteria Including the Proto-Mitochondrion

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    原始的ミトコンドリアDNA複製酵素の発見. 京都大学プレスリリース. 2024-02-22.DNA polymerases synthesize DNA from deoxyribonucleotides in a semiconservative manner and serve as the core of DNA replication and repair machinery. In eukaryotic cells, there are 2 genome-containing organelles, mitochondria, and plastids, which were derived from an alphaproteobacterium and a cyanobacterium, respectively. Except for rare cases of genome-lacking mitochondria and plastids, both organelles must be served by nucleus-encoded DNA polymerases that localize and work in them to maintain their genomes. The evolution of organellar DNA polymerases has yet to be fully understood because of 2 unsettled issues. First, the diversity of organellar DNA polymerases has not been elucidated in the full spectrum of eukaryotes. Second, it is unclear when the DNA polymerases that were used originally in the endosymbiotic bacteria giving rise to mitochondria and plastids were discarded, as the organellar DNA polymerases known to date show no phylogenetic affinity to those of the extant alphaproteobacteria or cyanobacteria. In this study, we identified from diverse eukaryotes 134 family A DNA polymerase sequences, which were classified into 10 novel types, and explored their evolutionary origins. The subcellular localizations of selected DNA polymerases were further examined experimentally. The results presented here suggest that the diversity of organellar DNA polymerases has been shaped by multiple transfers of the PolI gene from phylogenetically broad bacteria, and their occurrence in eukaryotes was additionally impacted by secondary plastid endosymbioses. Finally, we propose that the last eukaryotic common ancestor may have possessed 2 mitochondrial DNA polymerases, POP, and a candidate of the direct descendant of the proto-mitochondrial DNA polymerase I, rdxPolA, identified in this study

    Endosymbiotic Gene Transfer in Tertiary Plastid-Containing Dinoflagellates

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    Plastid establishment involves the transfer of endosymbiotic genes to the host nucleus, a process known as endosymbiotic gene transfer (EGT). Large amounts of EGT have been shown in several photosynthetic lineages but also in present-day plastid-lacking organisms, supporting the notion that endosymbiotic genes leave a substantial genetic footprint in the host nucleus. Yet the extent of this genetic relocation remains debated, largely because the long period that has passed since most plastids originated has erased many of the clues to how this process unfolded. Among the dinoflagellates, however, the ancestral peridinin-containing plastid has been replaced by tertiary plastids on several more recent occasions, giving us a less ancient window to examine plastid origins. In this study, we evaluated the endosymbiotic contribution to the host genome in two dinoflagellate lineages with tertiary plastids. We generated the first nuclear transcriptome data sets for the “dinotoms,” which harbor diatom-derived plastids, and analyzed these data in combination with the available transcriptomes for kareniaceans, which harbor haptophyte-derived plastids. We found low level of detectable EGT in both dinoflagellate lineages, with only 9 genes and 90 genes of possible tertiary endosymbiotic origin in dinotoms and kareniaceans, respectively, suggesting that tertiary endosymbioses did not heavily impact the host dinoflagellate genomes

    Inventory and Evolution of Mitochondrion-localized Family A DNA Polymerases in Euglenozoa

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    The order Trypanosomatida has been well studied due to its pathogenicity and the unique biology of the mitochondrion. In Trypanosoma brucei, four DNA polymerases, namely PolIA, PolIB, PolIC, and PolID, related to bacterial DNA polymerase I (PolI), were shown to be localized in mitochondria experimentally. These mitochondrion-localized DNA polymerases are phylogenetically distinct from other family A DNA polymerases, such as bacterial PolI, DNA polymerase gamma (Polγ) in human and yeasts, “plant and protist organellar DNA polymerase (POP)” in diverse eukaryotes. However, the diversity of mitochondrion-localized DNA polymerases in Euglenozoa other than Trypanosomatida is poorly understood. In this study, we discovered putative mitochondrion-localized DNA polymerases in broad members of three major classes of Euglenozoa—Kinetoplastea, Diplonemea, and Euglenida—to explore the origin and evolution of trypanosomatid PolIA-D. We unveiled distinct inventories of mitochondrion-localized DNA polymerases in the three classes: (1) PolIA is ubiquitous across the three euglenozoan classes, (2) PolIB, C, and D are restricted in kinetoplastids, (3) new types of mitochondrion-localized DNA polymerases were identified in a prokinetoplastid and diplonemids, and (4) evolutionarily distinct types of POP were found in euglenids. We finally propose scenarios to explain the inventories of mitochondrion-localized DNA polymerases in Kinetoplastea, Diplonemea, and Euglenida

    Morphological Diversity between Culture Strains of a Chlorarachniophyte, Lotharella globosa

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    Chlorarachniophytes are marine unicellular algae that possess secondary plastids of green algal origin. Although chlorarachniophytes are a small group (the phylum of Chlorarachniophyta contains 14 species in 8 genera), they have variable and complex life cycles that include amoeboid, coccoid, and/or flagellate cells. The majority of chlorarachniophytes possess two or more cell types in their life cycles, and which cell types are found is one of the principle morphological criteria used for species descriptions. Here we describe an unidentified chlorarachniophyte that was isolated from an artificial coral reef that calls this criterion into question. The life cycle of the new strain includes all three major cell types, but DNA barcoding based on the established nucleomorph ITS sequences showed it to share 100% sequence identity with Lotharella globosa. The type strain of L. globosa was also isolated from a coral reef, but is defined as completely lacking an amoeboid stage throughout its life cycle. We conclude that L. globosa possesses morphological diversity between culture strains, and that the new strain is a variety of L. globosa, which we describe as Lotharella globosa var. fortis var. nov. to include the amoeboid stage in the formal description of L. globosa. This intraspecies variation suggest that gross morphological stages maybe lost rather rapidly, and specifically that the type strain of L. globosa has lost the ability to form the amoeboid stage, perhaps recently. This in turn suggests that even major morphological characters used for taxonomy of this group may be variable in natural populations, and therefore misleading
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