Konno Toshihiro



Associate Professor

Researcher Number(JSPS Kakenhi)


Current Affiliation Organization 【 display / non-display

  • Duty   University of the Ryukyus   Faculty of Agriculture   Subtropical Agro-Environmental Sciences   Associate Professor  

  • Concurrently   University of the Ryukyus   Graduate School of Agriculture   Subtropical Agriculture   Associate Professor  

Graduate School 【 display / non-display


    Tohoku University  Graduate School, Division of Agriculture  Doctor's Course (second term)  Completed

Academic degree 【 display / non-display

  • Tohoku University -  Ph.D.

External Career 【 display / non-display

  • 2012.12

    University of the Ryukyus, Faculty of Agriculture, Department of Subtropical Agro-Environmental Sciences,Associate Professor  

Affiliated academic organizations 【 display / non-display

  • 1900.04

    Society for Reproduction and Development 

Research Interests 【 display / non-display

  • developmental biology

Research Areas 【 display / non-display

  • Others / Others

Research Theme 【 display / non-display

  • Mechanisms regulating trophoblast differentiation

Published Papers 【 display / non-display

  • The strong anti-hyaluronidase effect of ellagic acid markedly decreases polyspermy during in vitro fertilization, resulting in sustainment of the developmental potency in porcine oocytes.

    Kawasaki K, Hirai M, Ishiki Y, Nagahama A, Konno T, Yamanaka K, Tatemoto H

    Theriogenology ( Theriogenology )  215   95 - 102   2024.02 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    The present study investigated the effects of ellagic acid, a type of polyphenol that does not have a glycan and is composed of four hydroxyl groups and two lactone functional groups, on porcine in vitro fertilization (IVF) by focusing on its anti-hyaluronidase activity. A comparative analysis of ellagic acid and apigenin, which is commonly used as a hyaluronidase inhibitor, was performed. It compared the effects of ellagic acid and apigenin on hyaluronidase activity at different concentrations. The results showed that 10, 20, and 40 μM ellagic acid strongly reduced hyaluronidase activity (P < 0.05). The addition of 20 μM ellagic acid, but not apigenin, to porcine IVF medium effectively reduced polyspermy without decreasing sperm penetration or the formation rates of male pronuclei in cumulus-free oocytes. However, neither ellagic acid nor apigenin affected the number of sperm that bound to zona pellucida (ZP) or the induction of zona hardening and protease resistance. The percentage of acrosome-reacting sperm that bound to the ZP was markedly lower in the presence of 20 μM ellagic acid than in the untreated and apigenin-treated groups, even though the antioxidant capacity of ellagic acid was weaker than that of apigenin. Furthermore, a markedly higher percentage of embryos developed to the blastocyst stage in the ellagic acid-treated group, and the apoptotic indexes of expanded blastocysts produced by the ellagic acid treatment during IVF were significantly low. Therefore, the anti-hyaluronidase effect of ellagic acid markedly suppressed the induction of the acrosome reaction in sperm that bound to the ZP, resulting in a marked decrease in polyspermy under conditions that maintained high sperm penetrability during IVF and sustainment of the developmental potency in porcine oocytes.

  • Re-Evaluation of the Cross-Reactions of the Antibody against the Causative Agent for Paracoccidioidomycosis Ceti; Paracoccidioides ceti and the Related Fungal Species.

    Kanegae H, de Souza Suguiura IM, Tashiro R, Konno T, Hou DX, Sano A, Eto T, Ueda K, Hossain MA

    Microorganisms ( Microorganisms )  11 ( 10 )   2023.09 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Paracoccidioidomycosis ceti (PCM-C) is a chronic granulomatous keloidal dermatitis in cetaceans that has been reported worldwide and is caused by Paracoccidioides ceti. Serological cross-reactions among highly pathogenic fungal infections and related diseases have been reported. However, the true cross-reaction of antibodies against P. ceti has remained unknown due to the use of positive control sera from infected dolphins. This study aimed to re-evaluate antibodies from mechanically dislodged fungal cells in the infected tissue of a PCM-C case and demonstrate the actual cross-reaction. The results revealed a limited cross-reaction between PCM-C and paracoccidioidomycosis, while the antibodies did not react with other pathogens such as Coccidioides posadasii, Histoplasama capsulatum, and Arthrographis kalrae. Thus, the method for evaluation of the antibody against PCM-C is reliable, and there is potential for epidemiological study.

  • Antifreeze protein type III addition to freezing extender comprehensively improves post-thaw sperm properties in Okinawan native Agu pig.

    Masuda Y, Kheawkanha T, Nagahama A, Kawasaki K, Konno T, Yamanaka K, Tatemoto H

    Animal reproduction science ( Animal Reproduction Science )  252   107232 - 107232   2023.05 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Sperm cryopreservation often leads to physical cell damage through ice crystal formation. This study evaluates the improvements to freezing extender cryoprotective activity due to antifreeze protein (AFP) addition, which primarily acts on ice crystal formation, through investigating the post-thaw sperm properties of Okinawan native Agu pig. Six individual boar sperm samples were diluted with the freezing extender supplemented with 1 μg/mL of AFP I or AFP III and then subjected to cryopreservation. Treatment with AFP I during the freezing procedure had no improvement for any characteristics after thawing compared to untreated sperm. In contrast, the addition of AFP III to the freezing extender strongly increased sperm motility, mitochondria and cell membrane integrity, and the acrosomal proteolytic activity of frozen-thawed sperm in 5 of 6 individuals (P < 0.05). Furthermore, cryoinjury prevention by AFP III significantly enhanced sperm viability (by ATP content), and maintained DNA quality and in vitro sperm penetrability compared with AFP I treatment (P < 0.05). These findings demonstrate that AFP III addition to the freezing extender of boar sperm is more effective in maintaining sperm characteristics than the extender without AFP III or AFP I, despite individual differences in response.

  • Addition of l-carnitine to the freezing extender improves post-thaw sperm quality of Okinawan native Agu pig.

    Tatemoto H, Osokoshi N, Hirai M, Masuda Y, Konno T, Yamanaka K

    Theriogenology ( Theriogenology )  188   170 - 176   2022.08 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    The objective of the present study was to establish whether the addition of l-carnitine (LC), which exhibits antioxidant activity, to the freezing extender improves the quality of cryopreserved Okinawan native Agu pig sperm. Ejaculated sperm frozen in an extender supplemented with 0, 1, 2.5, or 5 mM LC was thawed, and the integrities of mitochondria and the plasmalemma and other sperm characteristics were evaluated. The treatment with different concentrations of LC effectively improved sperm motility, mitochondrial and plasmalemmal integrities, and the proteolytic activity of acrosomal contents after freeze-thawing (P < 0.05). The proportion of post-thaw sperm possessing intact mitochondria and plasmalemma and higher proteolytic activity of acrosomal contents was markedly higher among sperm frozen in the presence of 2.5 mM LC than among sperm frozen in the extender without LC (P < 0.05). Furthermore, although the addition of LC to the freezing extender had no effect on disturbance of DNA damage and caspase activity, sperm treated with 2.5 mM LC during freezing exhibited significantly higher penetrability into matured oocytes in vitro than untreated sperm. Collectively, these results indicate that the addition of LC to the freezing extender effectively improved the post-thaw quality of Agu pig sperm by preventing mitochondrial dysfunction caused by oxidative stress during cryopreservation.

  • Endoplasmic reticulum stress attenuation promotes bovine oocyte maturation in vitro.

    Khatun H, Wada Y, Konno T, Tatemoto H, Yamanaka KI

    Reproduction (Cambridge, England) ( Reproduction (Cambridge, England) )  159 ( 4 ) 361 - 370   2020.04 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    We have previously reported that regulation of endoplasmic reticulum (ER) stress during in vitro culture acutely increases bovine embryo developmental rate and cryotolerance; these data indicate that ER stress is a critical factor reducing the quality of in vitro-produced embryos. In the current follow-up study, we examined whether ER stress attenuation during in vitro maturation influences meiotic maturation, oocyte quality, and subsequent embryonic development. Bovine cumulus oocyte complexes (COCs) derived from slaughterhouse ovaries were matured with or without tauroursodeoxycholic acid (TUDCA), a selective inhibitor of ER stress (0, 50, 100, and 200 µM) for 22 h followed by in vitro fertilization, and zygotes were cultured for 8 days. Of the different doses of TUDCA, 100 μM TUDCA significantly increased the maturation rate, and decreased reactive oxygen species in denuded oocytes, and appeared lower number of apoptotic cells in matured COCs. Subsequently, treatment of TUDCA (100 µM) decreased the localization and amount of GRP78/BIP protein level as well as ER stress (GRP78/BIP, PERK, IER1, ATF4, and XBP1) and apoptosis (CHOP and BAX)-related gene expression, while it increased the anti-apoptotic gene BCL2 level in matured COCs. Moreover, addition of TUDCA (100 µM) during IVM significantly improved the blastocyst formation rate (43.6 ± 1.8% vs 49.7 ± 1.3%) and decreased the number of apoptotic cells (7.7 ± 1.1% vs 5.03 ± 0.6%) in blastocysts. These findings suggest that the presence of ER stress during maturation impairs the developmental competence of bovine COCs and that this process can be reversed by TUDCA.

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Presentations 【 display / non-display

  • Ovarian estrogen negatively regulates uterine eosinophil distribution during implantation window in mice.

    Tomomi Kurane, Akira Morooka, Toshihiro Konno

    OIST and Univ. Ryukyus Joint Symposium  (Okinawa)  2017.10  -  2017.10 

  • Mural trophectoderm specific activation of adhesion competence in peri-implantation murine blastocyst

    Ichiko Nishi, Fumie Kawase, Tomomi Murane, Keiichiro Ohta, Hideki Tatemoto, Toshihiro Konno

    4th World Congress of Reproductive Biology  (Okinawa)  2017.09  -  2017.09