Neuropeptides trigger oocyte maturation and subsequent spawning in the hydrozoan jellyfish Cytaeis uchidae |
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Authors: | Noriyo Takeda Yoko Nakajima Osamu Koizumi Toshitaka Fujisawa Toshio Takahashi Midori Matsumoto Ryusaku Deguchi |
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Institution: | 1. Department of Biosciences and Informatics, Keio University, Yokohama, Japan;2. Department of Biology, Keio University, Yokohama, Japan;3. Department of Environmental Science, Fukuoka Women's University, Fukuoka, Japan;4. Okazaki Institute for Integrative Bioscience/The Graduate University for Advanced Studies, Okazaki, Japan;5. Suntory Foundation for Life Sciences, Bioorganic Research Institute, Osaka, Japan;6. Department of Biology, Miyagi University of Education, Sendai, Japan |
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Abstract: | Oocyte maturation and subsequent spawning in hydrozoan jellyfish are generally triggered by light‐dark cycles. To examine if the initiation of the maturation process after light stimulus is mediated by neurotransmitters, neuropeptides isolated originally from Hydra magnipapillata were applied to sexually mature female medusae of the hydrozoan jellyfish Cytaeis uchidae. Among the Hydra neuropeptides tested, Hym‐53 (NPYPGLW‐NH2), as well as a nonphysiological peptide, CGLWamide (CGLW‐NH2), were most effective in inducing oocyte maturation and spawning. Hym‐355 (FPQSFLPRG‐NH2) also triggered these events, but the stimulatory effect was weaker. Since Hym‐53‐OH (NPYPGLW) and Hym‐355‐OH (FPQSFLPRG) had no effect, amidation at the C‐terminus may be critical for the stimulatory activities of the peptides. Exposure to Hym‐53 for 2 min was sufficient to trigger of oocyte maturation, and the spawned eggs were able to be fertilized and to develop normally. Transmission electron microscopy confirmed that bundles of axon‐like structures that contain dense‐core synaptic vesicles and microtubules are present in the ovarian ectodermal epithelium overlying the oocytes. In addition, immunohistological analyses revealed that some of the neurons in the ectodermal epithelium are GLWamide‐ and PRGamide‐positive. These results suggest that a neuropeptide signal transduction pathway is involved in mediating the induction of oocyte maturation and spawning in this jellyfish. Mol. Reprod. Dev. 80: 223–232, 2013. © 2013 Wiley Periodicals, Inc. |
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Keywords: | cnidaria ovary meiotic maturation GTH GnRH GLWamide RFamide PRGamide amidation |
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