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Speract induces calcium oscillations in the sperm tail
Chris D Wood1, Alberto Darszon, Michael Whitaker
1School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, NE2 4HH, UK.
The Journal of Cell Biology
|April 16, 2003
Summary
Sperm-activating peptides like speract cause complex calcium signals in sea urchin sperm. These signals, originating in the tail and spreading to the head, are crucial for understanding sperm motility.
Area of Science:
- Cellular Biology
- Reproductive Biology
- Biophysics
Background:
- Sperm motility is essential for fertilization.
- Sperm-activating peptides modulate sperm function.
- Intracellular calcium concentration ([Ca2+]i) plays a key role in sperm motility.
Purpose of the Study:
- To investigate the spatiotemporal dynamics of intracellular calcium ([Ca2+]i) changes in single sea urchin sperm.
- To elucidate the role of speract in modulating [Ca2+]i signals.
- To understand the relationship between [Ca2+]i dynamics and sperm motility.
Main Methods:
- High-resolution imaging of single sea urchin sperm.
- Measurement of intracellular free calcium concentration ([Ca2+]i) using fluorescence microscopy.
- Pharmacological manipulation using calcium channel blockers, anion channel blockers, and signaling pathway modulators.
Main Results:
- Speract induces periodic [Ca2+]i oscillations in the sperm tail, followed by a delayed increase in the sperm head.
- [Ca2+]i transients exhibit spontaneous occurrence in unstimulated sperm, with the head lagging the tail.
- Speract-induced [Ca2+]i signals are sensitive to membrane potential and ion channel activity, and are modulated by signaling pathways.
Conclusions:
- A model is proposed where a tail-generated messenger diffuses to the sperm head.
- Understanding [Ca2+]i dynamics at the single-cell level is critical for linking calcium signaling to sperm motility.
- Sperm polarization influences the propagation of calcium signals.