Publications by authors named "Keiichi Matsuura"

A new species of nine-spined stickleback, Pungitius modestus, is described based on the holotype and 17 paratypes (38.751.7 mm standard length) collected from the inland area of Yamagata Prefecture, northern Honshu, Japan.

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A new species of toby fish, Canthigaster aziz, is described based on a single specimen collected from the northern Red Sea off Saudi Arabia. The holotype was trawled from a depth of 315 m, the second deepest record for the genus. The new species is distinguished from other species of the genus by the following combination of characters: 8 dorsal-fin rays; 8 anal-fin rays; 15 pectoral-fin rays; dorsal-fin origin opposite to anal-fin origin; five diffuse, saddle-like, black blotches along dark yellowish dorsal edge of body between nape and dorsal-fin origin; dorsal half of body light brown with concentrated dark pigments just behind eye and with a longitudinal, irregular, pale golden stripe running from area just behind eye to dorsal side of caudal peduncle; ventral half of posterior part of body pinkish with tiny subcutaneous black spots; head and ventral half of body before anus white; and all fins uniformly pale grey.

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A new genus and species of the percoid family Symphysanodontidae, Cymatognathus aureolateralis are described based on three specimens collected from North Sulawesi, Indonesia. The new species shares with the confamilial genus Sym-physanodon the unique supraneural and spinous dorsal-fin pterygiophore insertion pattern usually of 0/0/0+2+1/1/, T-shaped first supraneural, foreshortened base of the penultimate ventral procurrent caudal-fin ray, well-developed outer tooth patches at anterior tips of both jaws as well as along the medial surface of most of the length of the coronoid process of the dentary. The new species, however, is distinguishable from members of Symphysanodon by the following diagnostic characters: posterior tip of coronoid process of dentary abruptly depressed, so that teeth on anterior portion appear as an elevated patch, anterior tip of upper jaw not notched, and posterior nostril horizontally slit-like.

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Catches of whitebait, sardine fry, sometimes contains other marine animals, including fishes, mollusks, and crustaceans, and therefore boiled and dried whitebait products may contain these marine animals if sorting is incomplete. In September 2014, contamination of boiled and dried whitebait products with pufferfish juveniles became a serious food safety concern, as tiger pufferfish Takifugu rubripes juveniles are toxic and contain tetrodotoxin (TTX). The toxicity of the juveniles of other pufferfish species, however, is unclear.

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The muscular system in the Pacific bluefin tuna Thunnus orientalis is studied in detail. For the first time, a complete description of the muscular anatomy of a thunnid is provided here. Eighty-two elements including subdivisions of components of the muscular system are identified.

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Homologies of the branchial arch muscles in the cyprinid Zacco platypus are assessed based on their innervation. Muscles serving the first gill arch are innervated by branches of the glossopharyngeal (IX) nerve and those serving other arches by the vagal (X) nerve. Absence of the levator posterior is confirmed.

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Although the fugu Takifugu rubripes has attracted attention as a model organism for genomic studies because of its compact genome, it is not generally appreciated that there are approximately 25 closely related species with limited distributions in the waters of East Asia. We performed molecular phylogenetic analyses and constructed a time tree using whole mitochondrial genome sequences from 15 Takifugu species together with 10 outgroups to examine patterns of diversification. The resultant time tree showed that the modern Takifugu species underwent explosive speciation during the Pliocene 1.

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Balistoid fishes have a unique and reduced pelvic fin structure, which does not exhibit paired structures. The pelvic complex exhibits reductive trends, but its rudimentary structure was retained among balistoids, and its unidirectional and parsimonious reduction in more derived lineages has been hypothesized based on morphology. We investigated the evolution of pelvic complex reduction in balistoids using whole mitochondrial genome (mitogenome) data from 33 species (27 newly determined during the study) that represent the entire morphological diversity of balistoids.

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Background: The order Tetraodontiformes consists of approximately 429 species of fishes in nine families. Members of the order exhibit striking morphological diversity and radiated into various habitats such as freshwater, brackish and coastal waters, open seas, and deep waters along continental shelves and slopes. Despite extensive studies based on both morphology and molecules, there has been no clear resolution except for monophyly of each family and sister-group relationships of Diodontidae + Tetraodontidae and Balistidae + Monacanthidae.

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Tetraodontiformes includes approximately 350 species assigned to nine families, sharing several reduced morphological features of higher teleosts. The order has been accepted as a monophyletic group by many authors, although several alternative hypotheses exist regarding its phylogenetic position within the higher teleosts. To date, acanthuroids, zeiforms, and lophiiforms have been proposed as sister-groups of the tetraodontiforms.

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We determined the whole mitochondrial genome sequence for spotted green pufferfish, Tetraodon nigroviridis (Teleostei: Tetraodontiformes). The genome (16,488 bp) contained 37 genes (two ribosomal RNA genes, 22 transfer RNA genes, and 13 protein-coding genes) plus control region as found in other vertebrates, with the gene order identical to that of typical vertebrates. The sequence was used to estimate phylogenetic relationships and divergence times among major lineages of fishes, including representative model organisms in fishes.

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The objective of these in vivo experiments was to assess the mutagenic potential of tripeptides as reflected by the ability of the test compound to induce the formation of micronuclei in mouse polychromatic erythrocytes. The test agents used in these experiments were (1) powdered Aspergillus oryzae protease casein hydrolysate (CH) and (2) powdered Lactobacillus helveticus-fermented milk (FM). Both test agents contain two tripeptides, L-valyl-L-prolyl-L-proline (VPP) and L-isoleucyl-L-prolyl-L-proline (IPP).

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The objective of this multiple-dose toxicity study was to assess the toxicological potential of two tripeptides, L-valyl-L-prolyl-L-proline (VPP) and L-isoleucyl-L-prolyl-L-proline (IPP), when administered once daily for 91 consecutive days to rats. The test article, powdered casein hydrolysate (CH) known to contain 0.6% VPP plus IPP, was prepared using Aspergillus oryzae protease.

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Article Synopsis
  • The study investigated the effects of casein hydrolysate containing peptides VPP and IPP on systolic blood pressure in individuals with high-normal blood pressure and mild hypertension through a single-blind, placebo-controlled trial.
  • A total of 131 volunteers were assigned to four groups, receiving different dosages (0, 1.8, 2.5, and 3.6 mg) of the hydrolysate for six weeks, with significant reductions in systolic blood pressure noted particularly in the higher dosage groups.
  • The results demonstrated a clear dose-dependent antihypertensive effect, particularly in mildly hypertensive subjects, while diastolic blood pressure showed no significant changes across all groups.
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The molecular characterization of two isoforms of 3-deoxy-d-manno-oct-2-ulosonate (KDO) -8-phosphate synthase (AtkdsA1 and AtkdsA2) from Arabidopsis is reported here. First, by isolating a full-length cDNA for AtkdsA1, it was confirmed that the deduced primary structures of AtkdsA1 and AtkdsA2 proteins were 93% identical. Functional expression and purification studies demonstrated the efficient catalytic activity of the AtkdsA1 enzyme to produce KDO-8-phosphate from phosphoenolpyruvate and d-arabinose-5-phosphate.

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