Starting transients in sea urchin sperm flagella

Area of Science:

• Cell Biology
• Biochemistry
• Sperm Motility

Background:

• Sperm motility is crucial for fertilization.
• Flagellar movement is driven by complex biochemical and biophysical processes.
• The roles of pH and adenosine triphosphate (ATP) in sperm flagellar dynamics are key research areas.

Purpose of the Study:

• To investigate the effects of pH and ATP on sea urchin sperm flagellar movement.
• To elucidate the distinct mechanisms underlying principal and reverse flagellar bends.
• To understand the relationship between flagellar structure, sliding, and motility.

Main Methods:

• Live and Triton-extracted sea urchin spermatozoa were used.
• Spermatozoa were subjected to varying pH levels and adenosine triphosphate (ATP) concentrations.
• Flagellar movement and bend formation were recorded using ciné film.

Main Results:

• Low pH induced immotility in both live and extracted spermatozoa.
• Adenosine triphosphate (ATP) addition restored motility and flagellar bending.
• Principal and reverse bends exhibited differential pH sensitivities, suggesting distinct generation mechanisms.
• Triton-extracted spermatozoa without ATP retained a basal bend, which propagated upon ATP supply.

Conclusions:

• Flagellar movement initiation involves synchronous sliding, forming principal bends.
• Pre-existing basal bends facilitate metachronous sliding within the bend.
• pH and ATP are critical regulators of sea urchin sperm flagellar mechanics.