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Jiong Chen - One of the best experts on this subject based on the ideXlab platform.

  • male specific markers developed by next generation sequencing confirmed an xx xy sex determination system in farmed ayu Plecoglossus altivelis
    Aquaculture, 2021
    Co-Authors: Yuhong Shi, Jiong Chen
    Abstract:

    Abstract Ayu (Plecoglossus altivelis) is a commercially important common osmeroid fish for freshwater fisheries. But little is known about the sex-determination (SD) mechanisms. Type IIB endonucleases restriction-site associated DNA sequencing (2b-RAD-seq) is a popular reduced representation method and shown to be an efficient and valuable way for identifying the sex-specific DNA fragments and SD systems. In this study, one male and one female were first whole-genome sequenced. The total size of high-quality genome assembly of the male was 434 Mb (14,900 scaffolds) and of the female 424 Mb (15,340 scaffolds). And ten males and ten females were then subjected to 2b-RAD-seq and isolated 124 candidate male-specific tags and no female-specific tags. The candidate male-specific tags were mapped to 14 male scaffolds, nine of which were aligned to the female allelic scaffolds, and the other five belonged to the candidate male-specific scaffolds. Thereinto, scaf162525, scaf184183, scaf192610 encoded 45 candidate genes in all, 9 of which had functional descriptions. Furthermore, the anti-Mullerian hormone type-2 receptor on scaf192610 was tentatively identified as a Y-linked duplicate copy (Amhr2by) of the autosomal counterpart (Amhr2a), demonstrating the potential role in the SD system of ayu. Based on the four selected male-specific loci, four sets of primers were designed to develop the multiplex-PCR assay. Results showed that the four male-specific markers could identify the genetic sex with 100% accuracy in 126 farmed mature ayu of the different source populations. In conclusion, the genome sequences from both sexes combined with 2b-RAD sequencing analyses from other males and females led to the isolation of male-specific scaffolds, supporting an XX/XY SD system in ayu. The multiplex-PCR assay based on male-specific markers can be applied to perform molecular sexing in ayu culture.

  • interplay between the gut microbiota and immune responses of ayu Plecoglossus altivelis during vibrio anguillarum infection
    Fish & Shellfish Immunology, 2017
    Co-Authors: Li Nie, Qianjin Zhou, Yan Qiao, Jiong Chen
    Abstract:

    Gut microbiota plays fundamental roles in protection against pathogen invasion. However, the mechanism and extent of responses of gut microbiota to pathogenic infection are poorly understood. This study investigated the gut bacterial communities and immune responses of ayu (Plecoglossus altivelis) upon exposure to Vibrio anguillarum. The succession of V. anguillarum infection was evidenced by increased expression of immune genes and bacterial loads in ayu tissues, which in turn altered the composition and predicted functions of gut bacterial community. The dynamics of gut bacterial diversity and evenness were temporally stable in control ayu but were reduced in infected subjects, particularly at the late stages of infection. Variations in the gut microbiota were significantly associated with the expression levels of TNF-α (P = 0.019) and IL-1 β (P = 0.013). The profiles of certain gut bacterial taxa were indicative of V. anguillarum infection. Compared with healthy controls, the ayu infected with V. anguillarum possessed less complex, fewer connected, and lower cooperative gut bacterial interspecies interaction, coinciding with significant shifts in keystone species. These findings imply that V. anguillarum infection substantially disrupted the compositions and interspecies interaction of ayu gut bacterial community, thereby altering gut microbial-mediated functions and inducing host immune responses. This study provides an integrated overview on the interaction between the gut microbiota and host immune responses to pathogen infection from an ecological perspective.

  • Molecular cloning, pathologically-correlated expression and functional characterization of the colonystimulating factor 1 receptor (CSF-1R) gene from a teleost, Plecoglossus altivelis
    Science Press PR China, 2016
    Co-Authors: Qiang Chen, Jiong Chen
    Abstract:

    Colony-stimulating factor 1 receptor (CSF-1R) is an important regulator of monocytes/macrophages (MO/MΦ). Although several CSF-1R genes have been identified in teleosts, the precise role of CSF- 1R in ayu (Plecoglossus altivelis) remains unclear. In this study, we characterized the CSF-1R homologue from P. altivelis, and named it PaCSF-1R. Multiple sequence alignment and phylogenetic tree analysis showed that PaCSF-1R was most closely related to that of Japanese ricefish (Oryzias latipes). Tissue distribution and expression analysis showed that the PaCSF-1R transcript was mainly expressed in the head kidney-derived MO/MΦ, spleen, and head kidney, and its expression was significantly altered in various tissues upon Vibrio anguillarum infection. After PaCSF-1R neutralization for 48 h, the phagocytic activity of MO/MΦ was significantly decreased, suggesting that PaCSF-1R plays a role in regulating the phagocytic function of ayu MO/MΦ

  • Comparative transcriptome analysis on the alteration of gene expression in ayu (Plecoglossus altivelis) larvae associated with salinity change
    Science Press PR China, 2016
    Co-Authors: Hao Zhang, Guan-jun Yang, Jiong Chen
    Abstract:

    Ayu (Plecoglossus altivelis) fish, which are an amphidromous species distributed in East Asia, live in brackish water (BW) during their larval stage and in fresh water (FW) during their adult stage. In this study, we found that FW-acclimated ayu larvae exhibited a slower growth ratio compared with that of BW-acclimated larvae. However, the mechanism underlying FW acclimation on growth suppression is poorly known. We employed transcriptome analysis to investigate the differential gene expression of FW acclimation by RNA sequencing. We identified 158 upregulated and 139 downregulated transcripts in FW-acclimated ayu larvae compared with that in BW-acclimated larvae. As determined by Gene Ontology annotation and Kyoto Encyclopedia of Genes and Genomes pathway mapping, functional annotation of the genes covered diverse biological functions and processes, and included neuroendocrinology, osmotic regulation, energy metabolism, and the cytoskeleton. Transcriptional expression of several differentially expressed genes in response to FW acclimation was further confirmed by real-time quantitative PCR. In accordance with transcriptome analysis, iodothyronine deiodinase (ID), pro-opiomelanocortin (POMC), betaine-homocysteine S-methyltransferase 1(BHMT), fructose-bisphosphate aldolase B (aldolase B), tyrosine aminotransferase (TAT), and Na+-K+ ATPase (NKA) were upregulated after FW acclimation. Furthermore, the mRNA expressions of b-type natriuretic peptide (BNP) and transgelin were downregulated after FW acclimation. Our data indicate that FW acclimation reduced the growth rate of ayu larvae, which might result from the expression alteration of genes related to endocrine hormones, energy metabolism, and direct osmoregulation

  • Molecular Characterization of E-Type Prostanoid Receptor 4 (EP4) from Ayu (Plecoglossus altivelis) and Its Functional Analysis in the Monocytes/Macrophages
    2016
    Co-Authors: Ye-jing Rong, Jiong Chen
    Abstract:

    Prostaglandin E2 (PGE2) plays an important role in a broad spectrum of physiological and pathological processes by interacting with E-type prostanoid receptors (EPs). EP4 is one of four EP subtypes known to mediate the immune response in mammalian monocytes/macrophages. However, the precise function and characteristics of EP4 in fish remain unclear. In this study, we characterized a novel EP4-like (PaEP4L) gene from ayu, Plecoglossus altivelis. The cDNA sequence of PaEP4L is 2781 nucleotides (nts) in length, encoding a polypeptide of 459 amino acid residues with a calculated molecular weight of 51.17 kDa. Sequence comparison and phylogenetic tree analysis showed that PaEP4L shared 76% amino acid identity with that of the Atlantic salmon (Salmo salar). PaEP4L mRNA was detected by real-time quantitative PCR (QPCR) in all tested tissues and head kidney-derived monocytes/macrophages (MO/MФ). It varied greatly in liver, spleen and MO/MФ upon Vibrio anguillarum infection. Western blot analysis revealed a significant increase of PaEP4L in cell homogenates from ayu MO/MФ upon V. anguillarum infection. Moreover, anti-PaEP4L IgG reversed the down-regulation of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) mRNA expression as well as phagocytosis in ayu MO/MФ caused by PGE2. There were no significant differences in the respiratory burst response between PGE2 treated and untreated cells. We further found that cAMP mediated PGE2/PaEP4L signal in ayu MO/MФ. In conclusion, our results indicate that PaEP4L mediates PGE2 effects on ayu MO/MФ function, revealing that EP4 also plays a role in the modulation of cells of the fish’s innate immune system.

Mutsumi Nishida - One of the best experts on this subject based on the ideXlab platform.

  • using dense locality sampling resolves the subtle genetic population structure of the dispersive fish species Plecoglossus altivelis
    Molecular Ecology, 2016
    Co-Authors: Hirohiko Takeshima, Kei'ichiro Iguchi, Yasuyuki Hashiguchi, Mutsumi Nishida
    Abstract:

    In dispersive species with continuous distributions, genetic differentiation between local populations is often absent or subtle and thus difficult to detect. To incorporate such subtle differentiation into management plans, it may be essential to analyse many samples from many localities using adequate numbers of high-resolution genetic markers. Here, we evaluated the usefulness of dense locality sampling in resolving genetic population structure in the ayu (Plecoglossus altivelis), a dispersive fish important in Japanese inland fisheries. Genetic variability in, and differentiation between, ayu populations around the Japan–Ryukyu Archipelago were investigated in 4746 individuals collected from 120 localities by genotyping 12 microsatellite markers. These individuals represented the two subspecies of ayu, namely the Ryukyuan subspecies (Plecoglossus altivelis ryukyuensis) and both amphidromous and landlocked forms of the nominotypical subspecies (P. a. altivelis) along the archipelago. We successfully detected an absence of genetic differentiation within the landlocked form and subtle but significant differentiation and clear geographic patterns of genetic variation among populations of the amphidromous form, which had been considered genetically homogeneous. This suggests that dense locality sampling effectively resolves subtle differences in genetic population structure, reducing stochastic deviation in the detection of genetic differentiation and geographic patterns in local populations of this dispersive species. Resampling analyses based on empirical data sets clearly demonstrate the effectiveness of increasing the number of locality samples for stable and reliable estimations of genetic fixation indices. The genetic population structure observed within the amphidromous form provides useful information for identifying management or conservation units in ayu.

Kenji Sakamoto - One of the best experts on this subject based on the ideXlab platform.

  • thermal tolerance traits of juveniles of the ayu Plecoglossus altivelis and japanese flounder paralichthys olivaceus evaluated by their caudal fin cells
    Aquaculture, 2005
    Co-Authors: Kenji Sakamoto, Masamichi Nakajima, Nobuhiko Taniguchi
    Abstract:

    The thermal tolerances of the ayu Plecoglossus altivelis and Japanese flounder Paralichthys olivaceus were evaluated by assaying the primary culture cells and the free cells from their caudal fins (at 43 °C for 2 h) in comparison with the whole body tolerances of juveniles (at 30 °C for the ayu and 32 °C for the Japanese flounder). Primary culture cells and free cells were assayed separately and similar results were obtained for each type of cells. The thermal tolerance values observed in the whole body were significantly correlated with the values obtained from both the primary culture cells and the free cells. These results suggest that there is a significant correlation between the in vivo and in vitro thermal tolerances in these fish. In the case of the ayu, significant differences were observed between two lines for the mean tolerance values evaluated by all three methods. This finding suggests that cell assays with primary culture cells or free cells from a caudal fin clip could be useful for evaluating the genetic variation and genetic mechanisms of thermal tolerance of fish.

Umino Tetsuya - One of the best experts on this subject based on the ideXlab platform.

  • Discrimination of stock origin of spawning population of ayu Plecoglossus altivelis altivelis at the Ota River, Hiroshima Prefecture
    広島大学大学院生物圏科学研究科, 2015
    Co-Authors: Koda Kazuya, Tamamori Chiharu, Goto Kento, Yamamoto Masaki, Takayama Sho, Umino Tetsuya
    Abstract:

    太田川下流域で採集したアユ産卵群の由来判別を外部形態および耳石Sr：Ca比分析で行った。太田川にて放流された人工種苗の耳石Sr：Ca比のチャートパターンは耳石中心から300μmで減少が認められ，耳石中心から400μm以遠で比が減少する天然型と異なっていた。耳石Sr：Ca 比のチャートパターンに基づくと，産卵群への人工種苗の混入率は28%と考えられた。採集した産卵群の側線上方横列鱗数は13～26枚（n=173）で，側線上方横列鱗数が17枚以下を人工種苗，18枚以上を天然アユと仮定すると，産卵群への人工種苗の混入率は31%と見積もられた。太田川産卵群では概ね3割が放流された人工種苗であると考えられた。Stock discrimination in the spawning population of ayu, Plecoglossus altivelis altivelis in the Ota River, western Japan was conducted using number of scales above the lateral line and otolith Sr:Ca ratio. Chart pattern in otolith Sr:Ca ratio of hatchery-stocked ayu was different in amphidromous form. Based on chart pattern of otolith Sr:Ca ratio, mixing ratio of hatchery-stocked ayu to the spawning population was estimated at 28%. Number of scales above the lateral line of spawning population marked from 13 to 26 (n=173). Based on number of scales above the lateral line (hatchery-stocked ayu ≦ 17; amphidromous ≧ 18), the mixing ratio of hatchery-stocked ayu was estimated 31%. Consequently, the contribution ratio of hatchery-stocked ayu to the spawning population was around 30% at the Ota River

  • Comparisons of Internal Behavior after Exposure to Flavobacterium psychrophilum between Two Ayu (Plecoglossus altivelis altivelis) Strains Showing Different Cumulative Mortality to Bacterial Cold Water Disease
    'Japanese Society of Veterinary Science', 2013
    Co-Authors: Kageyama Tetsushi, Umino Tetsuya, Kuwada Tomonori, Ohara Kenichi, Nouno Aya, Furusawa Shuichi
    Abstract:

    Bacterial cold water disease (BCWD) in ayu (Plecoglossus altivelis altivelis) has a serious impact on aquaculture and fisheries. There is known to be a significant difference among ayu strains with regard to mortality caused by BCWD. In this study, the immune response of different ayu strains against Flavobacterium psychrophilum infection was observed. One strain was resistant to infection by F. psychrophilum, and the other was susceptible to infection by the same bacteria. The number of bacteria in the body was observed in each ayu strain, and the change in bacterial counts was similar. However, there was a significant difference in bacterial count in the spleen between the two strains on days 6, 9, 12 and 15 after exposure. To observe the immune response against F. psychrophilum, agglutination assay using serum was performed. An agglutination reaction in the resistant ayu strain was observed in 4 out of 6 ayu on day 6 after exposure, while no reactions in the susceptible ayu strain were observed in any sampled fish until day 12. However, some reactions in the susceptible ayu strain were observed in surviving ayu. These results indicate that there is a correlation between the presence of bacterial multiplication and agglutination reaction against F. psychrophilum

  • Sock discrimination for juvenile ayu, Plecoglossus altivelis altivelis from stomach of field-caught Japanese seabass, Lateolabrax japonicas in the Nuta River, Hiroshima Prefecture
    広島大学大学院生物圏科学研究科, 2013
    Co-Authors: Urabe Atsushi, Umino Tetsuya
    Abstract:

    広島県沼田川下流域でスズキに捕食された稚アユの由来判別を，耳石結晶化および耳石Sr/Ca比を指標に行った。稚アユ7個体のうち，3個体は耳石の結晶化が認められたことから人工放流種苗とした。正常な耳石を有していた4個体の耳石Sr/Ca比分析を行ったところ，3個体が人工放流種苗で，天然遡上は1個体となった。結局，稚アユ7個体の由来は，天然遡上が1個体で，6個体は放流された人工放流種苗と考えられた。耳石形状やSr/Ca比分析は，外敵に捕食された稚アユの由来判別に有効であると考えられた。Stock discrimination study for juvenile ayu, Plecoglossus altivelis altivelis from stomach of Japanese seabass, Lateolabrax japonicus in the Nuta River estuary was conducted using prey otolith morphology and Sr/Ca profiling. Out of 7 individuals, 3 individuals identified as hatchery-stock ayu that had crystallized otolith. Based on the Sr/Ca profiling for 4 individuals that have normal otolith, 1 individual was identified as an amohidromous form and 3 individuals were identified as hatchery-stock ayu. The results showed that otolith-based approches could provide insight into stock discrimination for even highly digested ayu that have lost all phenotypic characteristics

  • Discrimination of amphidromous and landlocked ayu, Plecoglossus altivelis altivelis (Teleostei: Plecoglossidae) in the Nuta River, Hiroshima Prefecture, using the otolith Sr/Ca ratio
    広島大学大学院生物圏科学研究科, 2008
    Co-Authors: Yamamoto Kanako, Furusawa Shuichi, Umino Tetsuya, Shibata Yasuhiro, Takayama Sho, Nakamura Kazuo
    Abstract:

    6～8月にかけて主に沼田川中流域で採集したアユ30尾の耳石Sr/Ca比を調べ，由来判別を行った。その結果，30尾中12尾が天然遡上アユであることが判明した。また，支流の椋梨ダム湖（白竜湖）より上流の椋梨川で採集した13尾は，全ての個体で耳石Sr/Ca比の変動が認められなかったことから，これらはダム湖で再生産した陸封アユと考えられた。Ayu, Plecoglossus altivelis altivelis, is a commercially important species of amphidromous fish. Thus it is being targeted for stock replenishment to sustain harvest numbers. Stock identification between amphidromous and hatchery fish was conducted using the otolith Sr/Ca concentration ratio on fish taken from the Nuta River in Hiroshima Prefecture, where 170,000 hatchery ayu had been previously released. Of 30 fish sampled from the middle-reaches, 12 were identified as an amphidromous form. Of the 13 fish sampled from the Mukunashi River, a branch of the Nuta River, all were identified as landlocked fish that would have completed their life cycle between the Mukunashi River and the artificial lakes formed by the Mukunashi Dam.本研究は平成19年度広島大学地域貢献研究において，東広島市沼田川漁業協同組合より課題提案された「東広島市沼田川におけるアユの資源保全と有効利用」の一環として行った

  • Landlocked Ayu, Plecoglossus altivelis (Teleostei: Plecoglossidae) in the Ashida River, Hiroshima Prefecture, as Identified by Otolith Sr/Ca Ratio
    広島大学大学院生物圏科学研究科, 2007
    Co-Authors: Umino Tetsuya, Shiba Tomohisa, Kenzaki Hitomi, Shibata Yasuhiro, Nagasawa Kazuya
    Abstract:

    広島県芦田川中流・上流域で捕獲したアユ成魚10個体の耳石Sr/Ca比を調べ由来判別を行った。その結果, 9個体の耳石Sr/Ca比に変動がなく, 終始低レベルに推移したため, それらは仔稚魚期に海洋生活を送らなかった陸封アユと判断された。これら陸封アユは, 芦田川に建設された八田原ダムや三川ダムによって形成された人造湖(芦田湖, 神農湖)で再生産したものと考えられた。Ayu Plecoglossus altivelis is one of the most important freshwater fishes in Japan and usually amphidromous. Stock identification was conducted using otolith Sr/Ca analysis for ayu from the Ashida River, Hiroshima Prefecture. In nine of 10 adults sampled from the upper and middle-reaches in August-October 2006, the ratio did not fluctuate and remained at a low level, indicating that these ayu were landlocked fish without staying as larvae and juveniles in coastal marine waters. The landlocked ayu likely reproduce in two artificial lakes (Lake Ashida and Lake Jin-no formed by Hattabara Dam and Mikawa Dam, respectirely) in the Ashida River

Nagasawa Kazuya - One of the best experts on this subject based on the ideXlab platform.