Age-associated alteration of oocyte-specific gene expression in polar bodies: potential markers of oocyte competence.
OBJECTIVE
To confirm that oocyte-specific messenger RNAs are detectable in the polar body (PB) of metaphase II (MII) oocytes and determine the effect of age on oocyte-specific transcript levels.


METHODS
Prospective study.


METHODS
Hospital-based academic research laboratory.


METHODS
CD1 female mice.


METHODS
Aged (40-50 weeks) and young (7-9 weeks) mice were administered pregnant mare serum gonadotropin (PMSG) and hCG. Oocytes were fertilized in vitro to assess fertilization and developmental competence. The MII oocytes were obtained and first PBs were removed. Messenger RNAs from each PB and its sibling oocyte were reverse transcribed and analyzed by real-time quantitative polymerase chain reaction (PCR).


METHODS
Fertilization and developmental rates and expression of six oocyte-specific genes (Bmp15, Gdf9, H1foo, Nlrp5, Tcl1, and Zp3) in PBs and sibling oocytes from young versus aged mice.


RESULTS
Oocytes from aged mice had lower developmental competence. Four genes (H1foo, Nlrp5, Tcl1, and Zp3) were differentially expressed in aged versus young oocytes. All six transcripts were present in PBs from aged and young mice at lower levels than in the sibling oocytes; transcript levels were lower in aged PBs compared with young PBs.


CONCLUSIONS
There is a significant difference in the transcript levels of oocyte-specific genes in aged versus young PB that correlates with age-related decreases in oocyte competence. Differences in gene expression in PB may be potential biomarkers of MII oocyte competence.
Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
Ze-Xu
ZX
Jiao
Min
M
Xu
Teresa K
TK
Woodruff
D000375:Aging / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005819:Genetic Markers / Q000502:physiology; D008297:Male; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D059705:Polar Bodies / Q000502:physiology*; D011247:Pregnancy; D011446:Prospective Studies
D005819:Genetic Markers