Premises for fowl sperm preservation based on applied bioenergetics

Area of Science:

• Reproductive Biology
• Sperm Physiology
• Bioenergetics

Background:

• Sperm mobility assays are crucial for assessing sperm function.
• Understanding calcium (Ca2+) flux is vital for sperm preservation techniques, especially in avian species.
• Previous methods using 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) confirmed utility but did not fully address whole-cell Ca2+ flux.

Purpose of the Study:

• To determine if sperm mobility assays can yield predictive mathematical models of sperm cell function.
• To investigate sperm cell Ca2+ flux under simulated centrifugation conditions relevant to fowl sperm preservation.
• To establish relationships between sperm mobility, Ca2+ dynamics, and mitochondrial function.

Main Methods:

• Mobile sperm were rendered immobile using Accudenz and a Ca2+ chelator (BAPTA), then reactivated at body temperature.
• Sperm mobility, concentration, and velocity were measured using a Hobson SpermTracker under simulated centrifugation conditions (30°C, Ca2+ sink, no exogenous substrate).
• Mathematical functions were derived from motility data, and the effects of exogenous Ca2+ were assessed.

Main Results:

• Reactivated sperm mobility reached 93% of prewash levels, independent of time.
• Sperm motility parameters (concentration and velocity) followed parabolic functions over time, with observed maximums.
• Calcium flux dynamics, including intracellular redistribution and depletion, were characterized, with exogenous Ca2+ reversing depletion effects.

Conclusions:

• The sperm mobility assay is a valuable tool for predicting sperm function and optimizing in vitro conditions.
• Sperm Ca2+ flux is critical during manipulation, and its dynamics are linked to mitochondrial function and sperm preservation.
• Findings support four premises for fowl sperm preservation: importance of mobility phenotype, mitochondrial Ca2+ cycling, assay utility, and understanding whole-cell Ca2+ flux.