Identification of genes expressed in primate primordial oocytes.
BACKGROUND
The factors involved in oocyte survival and transition from quiescence to the growing phenotype remain unknown. Herein we report genes that are differentially expressed in the primordial oocyte revealed by DNA arrays.


METHODS
Primordial oocytes were captured selectively in rhesus monkey ovary sections using laser capture microdissection. The RNA was extracted and amplified in two rounds by T7-based linear RNA amplification, fluorescence labelled and then hybridized to human cDNA arrays containing 7680 elements. RNA from human placenta served as a reference sample.


RESULTS
Ninety-five genes were found to be consistently expressed at a higher level in primordial oocytes. Expression of several of these genes in the oocyte has been reported before, e.g. deleted in azoospermia (DAZ), prohibitin and transglutaminase 2. Oocyte expression of several novel transcripts revealed on array hybridization, such as gene 33, ubiquitin-conjugating enzyme E2A, G1 to S phase transition 1, growth arrest and DNA damage-inducible (GADD), and dendritic cell-derived ubiquitin-like protein (DC-UbP) was confirmed by in situ hybridization. Some array-identified gene products [integrin beta3, alpha-tubulin, regulatory telomere elongation protein (RAP1) and cellular repressor of EIA-stimulated genes (CREG protein)] were detected in human oocytes by immunofluorescence. Bioinformatic analysis of the oocyte-enriched transcripts reveals a functional profile summarized as follows: cell cycle (14%); transporter (13%); signal transduction (10%); cytoskeletal (7%); transcription factor (5%); immune response (5%); apoptosis-related (5%); RNA processing (5%); and the remainder of miscellaneous categories.


CONCLUSIONS
These observations may contribute to the elucidation of molecular pathways involved in oocyte survival and maturation.
Arraztoa
Jose A
JA
DEB, NICHD, NIH, Bethesda, MD 20892, USA.
Zhou
Jian
J
Marcu
David
D
Cheng
Clara
C
Bonner
Robert
R
Chen
Mei
M
Xiang
Charlie
C
Brownstein
Michael
M
Maisey
Kevin
K
Imarai
Monica
M
Bondy
Carolyn
C
D000818:Animals; D030541:Databases, Genetic; D005260:Female; D020869:Gene Expression Profiling; D008253:Macaca mulatta; D020411:Oligonucleotide Array Sequence Analysis; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D006080:Ovarian Follicle / Q000166:cytology / Q000502:physiology