Population genetic structure of Marbled Rockfish, Sebastiscus marmoratus (Cuvier, 1829), in the northwestern Pacific Ocean

Sebastiscus marmoratus is an ovoviviparous fish widely distributed in the northwestern Pacific. To examine the gene flow and test larval dispersal strategy of S. marmoratus in Chinese and Japanese coastal waters, 421 specimens were collected from 22 localities across its natural distribution. A 458 base-pair fragment of the mitochondrial DNA (mtDNA) control region was sequenced to examine genetic diversity and population structure. One-hundred-six variable sites defined 166 haplotypes. The populations of S. marmoratus showed high haplotype diversity with a range from 0.8587 to 0.9996, indicating a high level of intrapopulation genetic diversity. Low non-significant genetic differentiation was estimated among populations except those of Hyogo, Behai, and Niiigata, which showed significant genetic differences from the other populations. The demographic history examined by neutrality tests, mismatch distribution analysis, and Bayesian skyline analysis suggested a sudden population expansion dating to the late Pleistocene. Recent population expansion in the last glacial period, wide dispersal of larvae by coastal currents, and the homogeneity of the environment may have important influences on the population genetic pattern. Knowledge of genetic diversity and genetic structure will be crucial to establish appropriate fishery management of S. marmoratus

頭部SPECTにおけるステップと連続回転データ収集法の検討 : デジタルファントムによる検討

核医学検査における頭部SPECT検査を想定したステップ回転収集法と連続回転収集法による断層像のサンプリング角度の影響について，デジタルファントムを作成してシミュレーション解析による検討を行った．SPECTの連続回転収集法は，ステップ回転収集法のように検出器移動時の非データ収集というタイムロスが発生しない特徴があるが，標本化定理よりも大きなサンプリング角度を設定すると接線方向への画像歪が増加することが確認された．しかし，標本化定理に基づいたサンプリング角度を採用した場合は，連続回転収集法とステップ回転収集法によるSPECT像の画質がほぼ同等であることから，原理的に感度特性に優れた連続回転収集法を選択する方が良好な結果が得られると考えられた

運動パターンの違いがMR画像に及ぼす影響 : Radial Scanにおける検討

呼吸や血管の拍動などの周期的な動きがある被検体をMRI撮像する場合，画像再構成におけるk-スペースへのデータ充填法にRadial充填を使用すると動きによるボケ（モーションアーチファクト）を減少させることができる．本研究では，運動ファントムを使用してRadial充填の画像のアーチファクト低減効果を確認するとともに，Radial充填における動きの大きさや運動パターンの違いによるアーチファクトの出現特性について検証した．運動幅としては7㎜を超えると像のボケが大きくなり，アーチファクト低減効果は少ないと考えられた．また運動幅が大きい場合，運動距離が同じであっても運動周期に静止周期を含む場合では，ボケ発生の特性が異なることが確認できた．運動ファントムでモーションアーチファクトの検証実験を行う場合には，運動の大きさだけでなく対象の運動パターンを考慮して，実験を行わなければ，臨床上で現れる特性を再現できない可能性があるため注意が必要である

MRIにおける呼吸同期撮像法に関する基礎的検討

上腹部MRIの検査では,呼吸運動によってモーションアーチファクトが発生し,読影診断に影響を与えてしまうおそれがある.本研究ではアーチファクトを低減する方法のうち呼吸同期撮像法の特性について基礎的な実験を行った.呼吸同期撮像法では呼吸運動をセンサでモニタリングし,位置変動の少ない呼気相でのみ信号収集を行う撮像法である.模擬呼吸運動させたファントムを対象として信号収集のタイミングと信号収集期間を決定するパラメータであるトリガポイントを変化させて撮像を行った.アーチファクト低減効果を視覚的および画素データを使用したNMSE(Normalized Mean Square Error)を算出することで評価を実施した.結果としてファントムの動きが大きい位相に信号収集期間設定した場合ほど効果が見られず,呼吸運動波形にあったパラメータ設定を行うことが重要であることが確認できた

Phylogeography Study of Ammodytes personatus in Northwestern Pacific: Pleistocene Isolation, Temperature and Current Conducted Secondary Contact

To assess the role of historical process and contemporary factors in shaping population structures in Northwestern Pacific, mitochondrial control region sequences were analyzed to characterize the phylogeography and population structure of the Japanese sand lance Ammodytes personatus. A total of 429 individuals sampled from 17 populations through the species' range are sequenced. Two distinct lineages are detected, which might have been divergent in the Sea of Japan and Pacific costal waters of Japanese Island, during the low sea level. Significant genetic structure is revealed between the Kuroshio and Oyashio Currents. However, significant genetic structure is also detected in the Sea of Japan, contracting expected homogenization hypothesis in Tsushima Current. The haplotype frequency of lineages in both sides of Japanese Island and significant genetic structure between north and south groups revealed that the distribution of lineage B and north group were highly limited by the annual sea temperature. The lack of lineage B in Qingdao population with low sea temperature reflects the sea temperature barrier. Lack of genetic structure in the south group and north group populations indicated that ocean currents within groups facilitated the dispersal of A. personatus

Universal PCR primers for ribosomal protein gene introns of fish

Abstract Human ribosomal protein (RP) gene sequences with respect to intron/exon structures and corresponding cDNA or genomic data of fish species were obtained from the GenBank database. Based on conserved exon sequences, 128 primer pairs for 41 genes were designed for exon-primed intron-crossing (EPIC) polymerase chain reaction (PCR). In reference to the draft genome sequences of the Pacific bluefin tuna (Thunnus orientalis), 12 primer pairs expected to amplify introns of the bluefin tuna with lengths of 500–1000 bp were selected and applied to six distantly related fish species belonging to the Orders Clupeiformes, Tetraodontiformes, Pleuronectiformes, Perciformes, Scorpaeniformes, and Anguilliformes. PCR amplification was observed for at least four species in each primer pair, and all fragments were larger than those expected for intronless amplification. Single fragment amplification was observed for at least seven primer pairs per species. Fragment sizes of the bluefin tuna for nine primer pairs corresponded to those expected from the genomic data. Thus, our primer pairs are potentially applicable to a wide variety of fish species and serve as an initial step for isolating single-copy nuclear DNA sequences

Effect of glucosamine and related compounds on the degranulation of mast cells and ear swelling induced by dinitrofluorobenzene in mice.

AIMS: Glucosamine has been used safely to relieve osteoarthritis in humans, but the precise mechanism underlying its efficacy is still unclear. In this study, we investigated the direct effects of glucosamine and related compounds on mast cell mediated inflammation using cultured mast cells and an animal model. MAIN METHODS: Dinitrophenyl (DNP)-IgE-sensitized rat basophilic leukemia RBL-2H3 cells were treated with glucosamine-HCl (GlcN-HCl), N-acetylglucosamine (GlcNAc), chitin oligomer or chitosan oligomer. Cells were stimulated by DNP-BSA to induce degranulation and released beta-hexosaminedase was determined colorimetrically to measure the degree of degranulation. Dinitrofluorobenzene (DNFB) sensitized BALB/c mice were administrated orally with 1 or 0.1mg GlcN-HCl or GlcNAc for 6 days. One hour after the final administration, mice were challenged by DNFB to induce ear swelling. KEY FINDINGS: GlcN-HCl significantly inhibited the antigen-induced degranulation of RBL-2H3 cells at higher than 0.01 mg/mL for 24h-treatment while GlcNAc, a chitin oligomer and a chitosan oligomer had no effect. GlcN-HCl also suppressed intracellular calcium mobilization. GlcN-HCl and GlcNAc significantly suppressed the antigen-induced up-regulation of TNF-alpha and IL-6 mRNA. Ear swelling and histamine levels of plasma and ear in DNFB-treated mice were significantly suppressed by oral administration of GlcN-HCl or GlcNAc (0.1 and 1mg) for 6 days. SIGNIFICANCE: Our results strongly suggest that GlcN-HCl and GlcNAc have anti-inflammatory effects in vivo by suppressing the activation of mast cells