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Time-resolved sperm responses to an egg peptide measured by stopped-flow fluorometry
T Nishigaki1, F Z Zamudio, L D Possani
1Departamento de Genética y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62250, México.
Biochemical and Biophysical Research Communications
|June 8, 2001
Summary
Sea urchin speract triggers sperm responses with distinct time delays. These delays in intracellular pH and calcium changes reveal the sequence of biochemical signaling events.
Area of Science:
- Marine biology
- Sperm physiology
- Biochemistry
Background:
- Speract, a decapeptide from sea urchin egg jelly, is known to induce various sperm responses.
- Understanding the precise timing and mechanisms of these responses is crucial for reproductive biology.
Purpose of the Study:
- To investigate the temporal dynamics of speract-induced intracellular changes in sea urchin sperm.
- To elucidate the sequence of biochemical events following speract stimulation.
Main Methods:
- Utilized stopped-flow fluorometry to monitor real-time changes in sea urchin sperm.
- Employed labeled speract to track its binding and subsequent intracellular events.
- Measured intracellular pH (pH(i)) and calcium ion concentration ([Ca2+]i) dynamics.
Main Results:
- Observed significant time delays for the increase in intracellular pH (69 ms) and calcium (190 ms) after 200 nM speract stimulation.
- Identified a pH(i)-dependent affinity change in the speract receptor occurring around 129 ms.
- Demonstrated distinct temporal profiles for different signaling events.
Conclusions:
- The observed time delays suggest sequential biochemical processes govern sperm responses to speract.
- These findings provide insights into the intricate signaling cascade initiated by speract binding.
- The temporal resolution of these events is key to understanding sperm activation mechanisms.