Decreased expression of mitochondrial genes in human unfertilized oocytes and arrested embryos.
OBJECTIVE
To evaluate the relationship between mitochondrial gene expression of oocytes/embryos and their fertilizability in unfertilized oocytes, arrested embryos, and tripronucleate zygotes, because both nuclear and cytoplasmic factors contribute to oocyte activation, fertilization, and subsequent development.


METHODS
Prospective laboratory research.


METHODS
In vitro fertilization (IVF) laboratory in a university hospital.


METHODS
Seventy-five unfertilized oocytes, 45 arrested embryos, and 24 tripronucleate (3PN) embryos from 45 female patients undergoing IVF.


METHODS
Analysis of mitochondrial gene expression by semiquantitative reverse transcription polymerase chain reaction (RT-PCR).


METHODS
Comparison of the expression levels of mitochondrial genes including ND2, CO I, CO II, ATPase 6, CO III, ND3, ND6, and Cyt b in three groups.


RESULTS
Significantly decreased transcription levels were expressed in unfertilized oocytes and arrested embryos. The average expression levels of the eight determined genes compared with the control (GAPDH) was 4.4 +/- 0.7, 6.4 +/- 1.1, and 13.2 +/- 1.1 in unfertilized oocytes, arrested embryos, and 3PN embryos, respectively. Significantly decreased expressions of the ATPase 6, CO III, and ND3 genes were detected from samples with 4977-bp common deletion in the mitochondrial DNA (mtDNA) compared with the non-deletion group.


CONCLUSIONS
The present study is the first report to present globally decreased mitochondrial gene expression levels in human compromised oocytes and embryos. These data support the notion that the down-regulation of mitochondrial RNA by defective oxidative phosphorylation genes possibly affects oocyte quality including fertilization and further embryo development.
Hsieh
Rong-Hong
RH
Department of Obstetrics and Gynecology, Taipei Medical University Hospital, 250 Wu-Hsing Street, Taipei, Taiwan 110, Republic of China..
Au
Heng-Kien
HK
Yeh
Tien-Shun
TS
Chang
Shu-Ju
SJ
Cheng
Yu-Fei
YF
Tzeng
Chii-Ruey
CR
D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000502:physiology*; D005260:Female; D017353:Gene Deletion; D015870:Gene Expression; D006801:Humans; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology*; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
D004272:DNA, Mitochondrial