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Spermatozoa lacking acrosin protein show delayed fertilization
I M Adham1, K Nayernia, W Engel
1Institut für Humangenetik der Universität Göttingen, Germany.
Molecular Reproduction and Development
|March 1, 1997
Summary
Acrosin (ACR), a sperm enzyme, is not essential for fertility in mice. However, sperm lacking ACR show slower fertilization and a competitive disadvantage against normal sperm.
Area of Science:
- Reproductive Biology
- Enzymology
- Genetics
Background:
- Acrosin (ACR) is a sperm serine proteinase crucial for fertilization, aiding sperm binding to and penetration of the ovum's zona pellucida.
- The precise in vivo function of ACR in mammalian fertilization remains incompletely understood.
Purpose of the Study:
- To investigate the essentiality of acrosin for male fertility and fertilization in vivo.
- To elucidate the role of acrosin in sperm-zona pellucida interactions and fertilization dynamics.
Main Methods:
- Generation of acrosin-deficient (Acr-/-) mice using targeted gene disruption in embryonic stem cells.
- Assessment of fertility, litter size, and offspring viability in homozygous Acr-/- mice.
- In vitro fertilization assays comparing Acr-/- and wild-type (Acr+/+) sperm, including competitive fertilization experiments.
Main Results:
- Homozygous Acr-/- mice are fertile and produce litters comparable to wild-type Acr+/+ mice, indicating acrosin is not essential for fertility.
- Sperm from Acr-/- mice can penetrate the zona pellucida and fertilize oocytes, but fertilization is delayed compared to Acr+/+ sperm.
- In competitive in vitro fertilization, Acr+/+ sperm significantly outcompeted Acr-/- sperm, demonstrating a selective disadvantage for acrosin-deficient sperm.
Conclusions:
- Acrosin is not essential for male fertility or the ability of sperm to fertilize oocytes in mice.
- While not essential, acrosin plays a role in optimizing fertilization speed and provides a competitive advantage to sperm during fertilization.