Follicle microenvironment associated alterations in gene expression in the mouse oocyte and its polar body
Changes in the follicle microenvironment lead to quantifiable differences in gene expression in individual oocytes and their polar bodies.
Ze-Xu Jiao, M.D., Ph.D. and Teresa K. Woodruff, Ph.D.
Volume 99, Issue 5, Pages 1453-1459.e1, April 2013
To determine whether the follicle environment modulates oocyte-specific gene transcript levels in cultured oocytes and polar bodies (PB).
Large academic research center.
In vitro growth of secondary mouse follicles in 0.25% or 1.5% alginate (ALG) in a three-dimensional culture system.
Main outcome measures:
Relative RNA levels of Gdf9, Bmp15, Nlrp5, Tcl1, and Zp3 measured by real-time quantitative RT-PCR in oocytes during in vitro follicle development and oocyte maturation and in their first polar bodies after removal from MII eggs.
All transcripts decreased earlier in oocytes cultured in 1.5% ALG compared with 0.25% ALG. Transcript levels were lower in MII eggs cultured in 1.5% ALG compared with 0.25% ALG. All genes were expressed in PBs; levels were lower in follicles cultured in 1.5% ALG compared with 0.25% ALG. Abundance of all transcripts was lower in PBs than in their sibling oocytes.
Local follicle environment modulates oocyte-specific gene expression in the oocyte and first PB. There is a significant difference in the transcript levels of oocyte-specific genes in PB from 1.5% vs. 0.25% ALG that correlates with ovarian environment-related decreases in oocyte competence.