Differences in mitochondrial and nuclear DNA status of high-density and low-density sperm fractions after density...

To determine the mitochondrial DNA and nuclear DNA fragmentation of sperm populations separated by using discontinuous density gradient.

Analysis of mitochondrial and nuclear DNA status of sperm from high and low density layers.

Regional fertility center.

Twenty-eight men who presented for an initial infertility investigation.

Semen was prepared by using discontinuous density gradient (90.0%:45.0%) and subjected to a modified long polymerase chain reaction to assess mitochondrial DNA deletions and to a modified single-cell alkaline gel electrophoresis assay to determine nuclear DNA fragmentation.

The high-density fraction displayed significantly more wild-type mitochondrial DNA (75% of samples) than did the low-density fraction (25% of samples). In the high-density fraction, the incidence of single deletions was higher than that of double or multiple deletions, and the deletions were predominantly small. A strong correlation was observed between nuclear DNA fragmentation and the number and size of mitochondrial DNA deletions.

Density centrifugation isolates a population of sperm with high-quality mitochondrial DNA and nuclear DNA.