A comparison of mitochondrial and nuclear DNA status in testicular sperm from fertile men and those with obstructive azoospermia.
BACKGROUND
Mitochondria are vital to sperm as their motility powerhouses. They are also the only animal organelles with their own unique genome; encoding subunits for the complexes required for the electron transfer chain.


METHODS
A modified long PCR technique was used to study mitochondrial DNA (mtDNA) in ejaculated and testicular sperm samples from fertile men undergoing vasectomy (n = 11) and testicular sperm from men with obstructive azoospermia (n = 25). Nuclear DNA (nDNA) fragmentation was measured by an alkaline gel electrophoresis (comet) assay.


RESULTS
Wild-type mtDNA was detected in only 60% of fertile men's testicular sperm, 50% of their ejaculated sperm and 46% of testicular sperm from men with obstructive azoospermia. The incidence of mitochondrial deletions in testicular sperm of fertile and infertile men was not significantly different, but the mean size of the deletions was significantly less in testicular sperm from fertile men compared with men with obstructive azoospermia (P < 0.02). NDNA fragmentation in testicular sperm from fertile men and men with obstructive azoospermia was not significantly different.


CONCLUSIONS
Multiple mtDNA deletions are common in testicular and ejaculated sperm from both fertile and infertile men. However, in males with obstructive azoospermia, the mtDNA deletions in testicular sperm are of a larger scale.
O'Connell
M
M
School of Medicine, Department of Obstetrics and Gynaecology, Queens' University Belfast, Institute of Clinical Science, Grosvenor Road, Belfast BT12 6BJ, UK.
McClure
N
N
Lewis
S E M
SE
D001483:Base Sequence; D016022:Case-Control Studies; D004247:DNA / Q000235:genetics*; D053938:DNA Fragmentation; D004272:DNA, Mitochondrial / Q000235:genetics*; D005298:Fertility / Q000235:genetics; D006801:Humans; D008297:Male; D009845:Oligospermia / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D013094:Spermatozoa / Q000378:metabolism*; D013737:Testis / Q000378:metabolism
D004272:DNA, Mitochondrial; D004247:DNA