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06:08
Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
8.7K
Intracellular Ca2+ threshold reversibly switches flagellar beat off and on
C Sánchez-Cárdenas1, F Montoya2, F A Navarrete3
1Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Mor., México.
Biology of Reproduction
|June 13, 2018
Summary
Sperm motility relies on precise calcium regulation. Lowering intracellular calcium below a specific threshold is crucial for sperm to regain flagellar beating and motility after temporary immobilization.
Area of Science:
- Reproductive Biology
- Sperm Physiology
- Cellular Signaling
Background:
- Sperm motility is vital for fertilization and is regulated by intracellular calcium ([Ca2+]i).
- Previous studies showed high calcium ionophore A23187 concentrations immobilize sperm, with recovery upon removal.
- Defects in calcium regulation impact sperm function, highlighting its importance.
Purpose of the Study:
- To elucidate the precise intracellular calcium concentration ([Ca2+]i) thresholds that control sperm motility and flagellar beating.
- To investigate the relationship between dynamic changes in [Ca2+]i and sperm flagellar activity.
Main Methods:
- Developed a novel tool for simultaneous measurement of intracellular calcium ([Ca2+]i) and flagellar beat parameters in individual spermatozoa.
- Utilized the calcium ionophore A23187 to manipulate [Ca2+]i levels in sperm.
- Assessed sperm motility recovery and hyperactivation following controlled [Ca2+]i changes.
Main Results:
- Spermatozoa exhibit increased flagellar beating at high A23187 concentrations before immobilization.
- Concentration-dependent effects of A23187 on [Ca2+]i and motility were observed, with hyperactivation at lower concentrations and immobilization at higher ones.
- A critical finding is that [Ca2+]i must decrease below a defined threshold for flagellar beat recovery and restored sperm motility.
Conclusions:
- Intracellular calcium concentration ([Ca2+]i) acts as a critical switch for sperm motility.
- Understanding the [Ca2+]i thresholds is key to comprehending sperm function and potential infertility causes.
- The developed method provides a new approach to study the dynamic interplay between calcium and sperm motility.
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