Abstract
The cell egg is in a state of quiescence and only after its fusion with the sperm, a series of pre-programmed metabolic processes will be activated, culminating with embryonic development. The egg/sperm fusion induces a transitory increase of Ca(2+) in the cytoplasm, which is responsible for the activation of both precocious and late reactions. The release of Ca(2+) occurs by stimulation of the ionic specific channels. In addition to IP(3), a new Ca-release inducer was recently evidenced, cyclic ADP ribose (cADPR), in some invertebrates and mammals. Here, we report the first evidence of the cADPR presence in fish. Our data also demonstrate that in the sea bream egg, cADPR is involved in the fertilization process; in fact, its level increases after the entrance of the sperm. By in vitro experiments, it was shown that cADPR induces a release of Ca(2+) in the egg homogenate, indicating that in sea bream, the increase of cADPR can induce an intracellular Ca(2+) release. Since cADPR is a product of NAD(+) metabolism, the activity of several enzymes involved in the NAD(+) metabolism was investigated. Sea bream eggs are pelagic and only floating eggs after insemination develop into viable embryos. In the present work, NAD(+) metabolism was studied in both types of egg. All the tested enzymes showed similar specific activity in both floating and sinking eggs. In the latter, cADPR was not detectable and the nucleotides content was significantly lower, evidencing a scarce energetic charge in sinking eggs.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.