Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i>
In Phlebobranchiata ascidians, oocytes and spermatozoa are stored in the oviduct and spermiduct, respectively, until spawning occurs. Gametes in the gonoducts are mature and fertilizable; however, it was found that the gametes of the ascidians <i>Phallusia philippinensis</i> and <i>...
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MDPI AG
2023-01-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/3/2666 |
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| author | Noburu Sensui Yosinori Itoh Nobuhiko Okura Kogiku Shiba Shoji A. Baba Kazuo Inaba Manabu Yoshida |
| author_facet | Noburu Sensui Yosinori Itoh Nobuhiko Okura Kogiku Shiba Shoji A. Baba Kazuo Inaba Manabu Yoshida |
| author_sort | Noburu Sensui |
| collection | DOAJ |
| description | In Phlebobranchiata ascidians, oocytes and spermatozoa are stored in the oviduct and spermiduct, respectively, until spawning occurs. Gametes in the gonoducts are mature and fertilizable; however, it was found that the gametes of the ascidians <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> could not undergo fertilization in the gonoductal fluids. The body fluids of the ascidians, especially in the gonoducts, were much more acidic (pH 5.5–6.8) than seawater (pH 8.2), and the fertilization rate was low under such acidic conditions. Hence, we examined the effect of pH on gametes. Pre-incubation of gonoductal eggs at pH 8.2 prior to insemination increased fertilization rates, even when insemination was performed under low pH conditions. Furthermore, an increase in ambient pH induced an increase in the intracellular pH of the eggs. It was also found that an increase in ambient pH triggered the release of sperm attractants from the egg and is therefore necessary for sperm chemotaxis. Hence, acidic conditions in the gonoductal fluids keep the gametes, especially eggs, infertile, and the release of eggs into seawater upon spawning induces an increase in ambient pH, which enables egg fertilization. |
| first_indexed | 2024-03-11T09:41:19Z |
| format | Article |
| id | doaj.art-e28191b85eab4966afd3f1302d467369 |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-11T09:41:19Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-e28191b85eab4966afd3f1302d4673692023-11-16T17:00:32ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-01-01243266610.3390/ijms24032666Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i>Noburu Sensui0Yosinori Itoh1Nobuhiko Okura2Kogiku Shiba3Shoji A. Baba4Kazuo Inaba5Manabu Yoshida6Department of Human Biology and Anatomy, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0213, JapanDepartment of Human Biology and Anatomy, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0213, JapanDepartment of Molecular Anatomy, Faculty of Medicine, University of the Ryukyus, Nishihara 903-0213, JapanShimoda Marine Research Center, University of Tsukuba, Shimoda 415-0025, JapanDepartment of Biology, Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, JapanShimoda Marine Research Center, University of Tsukuba, Shimoda 415-0025, JapanMisaki Marine Biological Station, School of Science, The University of Tokyo, Miura 238-0225, JapanIn Phlebobranchiata ascidians, oocytes and spermatozoa are stored in the oviduct and spermiduct, respectively, until spawning occurs. Gametes in the gonoducts are mature and fertilizable; however, it was found that the gametes of the ascidians <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> could not undergo fertilization in the gonoductal fluids. The body fluids of the ascidians, especially in the gonoducts, were much more acidic (pH 5.5–6.8) than seawater (pH 8.2), and the fertilization rate was low under such acidic conditions. Hence, we examined the effect of pH on gametes. Pre-incubation of gonoductal eggs at pH 8.2 prior to insemination increased fertilization rates, even when insemination was performed under low pH conditions. Furthermore, an increase in ambient pH induced an increase in the intracellular pH of the eggs. It was also found that an increase in ambient pH triggered the release of sperm attractants from the egg and is therefore necessary for sperm chemotaxis. Hence, acidic conditions in the gonoductal fluids keep the gametes, especially eggs, infertile, and the release of eggs into seawater upon spawning induces an increase in ambient pH, which enables egg fertilization.https://www.mdpi.com/1422-0067/24/3/2666ascidianfertilizing abilitysperm chemotaxisoocyte maturation |
| spellingShingle | Noburu Sensui Yosinori Itoh Nobuhiko Okura Kogiku Shiba Shoji A. Baba Kazuo Inaba Manabu Yoshida Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> International Journal of Molecular Sciences ascidian fertilizing ability sperm chemotaxis oocyte maturation |
| title | Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> |
| title_full | Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> |
| title_fullStr | Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> |
| title_full_unstemmed | Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> |
| title_short | Spawning-Induced pH Increase Activates Sperm Attraction and Fertilization Abilities in Eggs of the Ascidian, <i>Phallusia philippinensis</i> and <i>Ciona intestinalis</i> |
| title_sort | spawning induced ph increase activates sperm attraction and fertilization abilities in eggs of the ascidian i phallusia philippinensis i and i ciona intestinalis i |
| topic | ascidian fertilizing ability sperm chemotaxis oocyte maturation |
| url | https://www.mdpi.com/1422-0067/24/3/2666 |
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