Increased Telomerase Reverse Transcriptase Expression Associates with Spontaneous Exit from M-II Arrest in Rat Eggs

Area of Science:

• Reproductive Biology
• Cellular Aging
• Mammalian Oogenesis

Background:

• Postovulatory egg aging in mammals can compromise egg quality.
• Potential mechanisms include spontaneous meiosis-II (M-II) exit and apoptosis.

Purpose of the Study:

• To investigate telomerase reverse transcriptase (TERT) expression, Bcl2 levels, and DNA fragmentation during mammalian egg aging.
• To compare aging processes in vivo and in vitro.

Main Methods:

• Assessment of spontaneous M-II exit in aged eggs (in vivo and in vitro).
• Quantification of TERT and Bcl2 expression.
• Detection of DNA fragmentation.

Main Results:

• Postovulatory aging increased spontaneous M-II exit in a time-dependent manner, with higher rates in vitro.
• TERT expression increased with aging, correlating with M-II exit.
• Bcl2 levels remained stable, and DNA fragmentation was absent up to 7 hours of aging.

Conclusions:

• Early postovulatory egg aging (up to 7 hours) is characterized by increased TERT expression and spontaneous M-II exit.
• Apoptosis, indicated by Bcl2 decrease or DNA fragmentation, is not a primary feature of early egg aging.