論文

© 2019 Tamaki et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The unicellular microalga Euglena gracilis produces wax esters for ATP acquisition under low-oxygen conditions. The regulatory mechanism of wax ester production is not yet understood. Indeed, our previous transcriptomic analysis showed that transcript levels of genes involved in the wax ester synthesis hardly changed under hypoxic conditions, suggesting contribution of post-transcriptional regulation. In this study, we conducted a proteome analysis of E. gracilis mitochondria, as this organelle employs the fatty-acid synthesis pathway under hypoxic conditions. Mitochondria were isolated from E. gracilis SM-ZK strain treated with both aerobic and hypoxic conditions and used for shotgun proteomic analysis. Three independent proteomic analyses succeeded in identifying a total of 714 non-redundant proteins. Of these, 229 were detected in common to all experiments, and 116 were significantly recognized as differentially expressed proteins. GO enrichment analysis suggested dynamic changes in mitochondrial metabolic pathways and redox reactions under aerobic and hypoxic conditions. Protein levels of bifunctional enzymes isocitrate lyase and malate synthase in glyoxylate cycle were 1.35-fold higher under hypoxic conditions. Abundances of the propionyl- CoA synthetic enzymes, succinyl-CoA synthetase and propionyl-CoA carboxylase, were also 1.35- and 1.47-fold higher, respectively, under hypoxic conditions. Protein levels of pyruvate: NADP+ oxidoreductase, a key enzyme for anaerobic synthesis of acetyl-CoA, which serves as a C2 donor for fatty acids, showed a 1.68-fold increase under hypoxic conditions, whereas those of pyruvate dehydrogenase subunits showed a 0.77-0.81-fold decrease. Protein levels of the fatty-acid synthesis enzymes, 3-ketoacyl-CoA thiolase isoforms (KAT1 and KAT2), 3-hydroxyacyl-CoA dehydrogenases, and acyl-CoA dehydrogenase were up-regulated by 1.20- to 1.42-fold in response to hypoxic treatment. Overall, our proteomic analysis revealed that wax ester synthesis-related enzymes are up-regulated at the protein level posttranscriptionally to promote wax ester production in E. gracilis under low-oxygen conditions.

© 2019 Zoological Society of Japan. Reproductive strategy is an important aspect of biological diversity. In tardigrades, several reproductive modes, including sexual reproduction, are known. However, tardigrade mating behavior has been observed only rarely in most species, and in some cases, especially in the freely ovipositing eutardigrades, remains entirely unknown. In the present study, we cultured two sexually reproducing tardigrade species that lay eggs freely, Paramacrobiotus sp. TYO strain and Macrobiotus shonaicus, to investigate and compare their courtship, mating, and chromosome morphology. Mating behavior was observed and recorded in both species. The entire mating sequence, including courtship, was categorized into five discrete steps common to two species, as follows: [1] Tracking: the male tracks and orientates toward the female; [2] Touching: the male makes contact with the cloaca of the female; [3] Standstill: the female ceases movement until male ejaculation is complete; [4] Ejaculation: the male curls its caudal end and ejaculates into the cloaca from close range; [5] Contraction: the female contracts its ventral side after ejaculation to capture spermatozoa deposited in the external environment in close proximity to the cloaca. Some notable differences between the two species were observed in the steps 3-4. First, oviposition was observed at 40 min in Paramacrobiotus sp. TYO strain, and a few days after mating in M. shonaicus, respectively. Comparisons of chromosome morphology before and after mating indicated that oocytes are arrested at metaphase I in both species. Spermatozoa attach to the interior of the chorion of laid eggs.

© 2019 The Author(s). Background: Tardigrades are microscopic organisms, famous for their tolerance against extreme environments. The establishment of rearing systems of multiple species has allowed for comparison of tardigrade physiology, in particular in embryogenesis. Interestingly, in-lab cultures of limnic species showed smaller variation in hatching timing than terrestrial species, suggesting a hatching regulation mechanism acquired by adaptation to their habitat. Results: To this end, we screened for coordinated gene expression during the development of two species of tardigrades, Hypsibius exemplaris and Ramazzottius varieornatus, and observed induction of the arthropod molting pathway. Exposure of ecdysteroids and juvenile hormone analog affected egg hatching but not embryonic development in only the limnic H. exemplaris. Conclusion: These observations suggest a hatching regulation mechanism by the molting pathway in H. exemplaris.

Copyright © 2020 Murai et al. Bacillus sp. strain KH172YL63 is a Gram-positive bacterium isolated from the deep-sea floor surface sediment at 3,308 m below sea level in the Nankai Trough in Japan. Here, we report the complete genome sequence of Bacillus sp. strain KH172YL63, which has a genome size of 4,251,700 bp and a G+C content of 44.8%.

Copyright © 2020 Inoue et al. We report the complete genome sequence of Bifidobacterium longum strain Jih1, isolated from human feces. The assembled genome comprised one circular chromosome of 2.37 Mb. The chromosome harbors 1,941 protein-coding genes.

© 2020 Takeyama et al. Halomonas hydrothermalis strain Slthf2 is a Gram-negative bacterium isolated from low-temperature hydrothermal fluids in South Pacific Ocean vent fields located at 2,580-m depth. Here, we report the complete genome sequence of this strain, which has a genome size of 4.12 Mb, with a GC content of 53.2%.

© 2020 Kurihara et al. Halomonas meridiana strain Eplume2 (ATCC BAA-804) is a Gram-negative bacterium isolated from hydrothermal plume seawater in the Northeast Pacific Ocean at a depth of 2,000 m. Here, we report the complete genome sequence of this strain, which has a total size of 4.12 Mbp and a 56.6% G+C content.

Copyright © 2020 Takahashi et al. Halomonas meridiana strain Slthf1 (ATCC BAA-801) is a Gram-negative bacterium that was isolated from a thermal vent in 1998. Here, we report the complete genome sequence of this strain, which has a 3.6-Mbp genome, containing 3,400 protein-coding sequences.

© 2019 Nagata et al. Here, we report the complete genome sequence of Halomonas olivaria strain TYRC17, a moderately halophilic, Gram-negative bacterium that was isolated from olive processing effluents. The 5-Mbp genome consists of 7,375 protein-coding sequences, including a variety of genes involved in tyrosol metabolism, nitrate respiration, and the production of polysaccharides.

Copyright © 2019 Saito et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. We report the complete genome sequence of Halomonas sulfidaeris ATCC BAA-803, isolated from a metal sulfide rock at a depth of 2,200 m in the Northeast Pacific Ocean. The assembled genome comprised one circular chromosome of 4.20 Mb and one large plasmid of 273 kb. The chromosome harbors 6,705 protein-coding genes.

Copyright © 2019 Tsurumaki et al. Halomonas axialensis is a halophilic bacterial species discovered near a deep-sea hydrothermal vent. Here, we report the first single closed genome sequence of the original strain, Halomonas axialensis strain Althf1. The genome was assembled by Nanopore sequencing and consisted of a single chromosome of 3.6 Mbp with 56.8% G+C content.

Copyright © 2019 Evans-Yamamoto et al. Psychrobacter sp. strain KH172YL61 is a Gram-negative bacterium isolated from deep-sea sediment in the Nankai Trough in Japan. Here, we report the complete genome sequence of this strain, which has a genome size of 3.19 Mb, with a GC content of 44.0%.

Copyright © 2020 Seo et al Cutibacterium acnes was reported as one of the most frequently isolated opportunistic pathogens among the skin microbiota. Here, we report two complete genome sequences of Cutibacterium acnes strains that were isolated from surgical (strain SZ1) and nonsurgical (strain SZ2) sites on the back of an orthopedic surgery patient.

Copyright © 2020 Magnolia Press. To date, only seven species of Macrobiotidae (Parachela; Eutardigrada; Tardigrada) have been reported from Japan, including the recently described Macrobiotus shonaicus Stec et al., 2018 from the Shonai region of Japan. This species has flexible filaments on the egg processes and is known to proliferate only through sexual reproduction. Here, we report a multifaceted analysis of nine populations of M. shonaicus found on four Japanese islands. DNA sequencing of the cytochrome oxidase subunit I (COI) and internal transcribed spacer 2 (ITS-2) of the nine populations revealed 8 and 11 haplotypes, respectively. The extensive morphometric analysis showed considerably greater variability in the morphology of eggs than of animals. In addition to the morphological and molecular data, we confirmed the karyotype and found that all populations had a chromosome number of n = 6. Moreover, we observed and filmed mating behaviour between all studied populations of M. shonaicus. Our results clearly indicated that M. shonaicus is widely distributed throughout Japan.

© 2018 The Authors. Colour vision is known to have arisen only twice—once in Vertebrata and once within the Ecdysozoa, in Arthropoda. However, the evolutionary history of ecdysozoan vision is unclear. At the molecular level, visual pigments, composed of a chromophore and a protein belonging to the opsin family, have different spectral sensitivities and these mediate colour vision. At the morphological level, ecdysozoan vision is conveyed by eyes of variable levels of complexity; from the simple ocelli observed in the velvet worms (phylum Onychophora) to the marvellously complex eyes of insects, spiders, and crustaceans. Here, we explore the evolution of ecdysozoan vision at both the molecular and morphological level; combining analysis of a large-scale opsin dataset that includes previously unknown ecdysozoan opsins with morphological analyses of key Cambrian fossils with preserved eye structures. We found that while several non-arthropod ecdysozoan lineages have multiple opsins, arthropod multi-opsin vision evolved through a series of gene duplications that were fixed in a period of 35 – 71 million years (Ma) along the stem arthropod lineage. Our integrative study of the fossil and molecular record of vision indicates that fossils with more complex eyes were likely to have possessed a larger complement of opsin genes.

© 2019 Japanese Society of Developmental Biologists Molecular biology has been led by various measurement technologies, and increased throughput has developed omics analysis. The development of massively parallel sequencing technology has enabled access to fundamental molecular data and revealed genomic and transcriptomic signatures. Nanopore sequencers have driven such evolution to the next stage. Oxford Nanopore Technologies Inc. provides a new type of single molecule sequencer using protein nanopore that realizes direct sequencing without DNA synthesizing or amplification. This nanopore sequencer can sequence an ultra-long read limited by the input nucleotide length, or can determine DNA/RNA modifications. Recently, many fields such as medicine, epidemiology, ecology, and education have benefited from this technology. In this review, we explain the features and functions of the nanopore sequencer, introduce various situations where it has been used as a critical technology, and expected future applications.