novel large-scale deletion of the mitochondrial DNA of spermatozoa of men in North Iran

To investigate the level of correlation between large-scale deletions of the mitochondrial DNA [mtDNA] with defective sperm function. In this analytic study, a total of 25 semen samples of the normozoospermic infertile men from North of Iran were collected from the IVF center in an infertility clinic. The swim-up procedure was performed for the separation of spermatozoa into two groups; [normal motility group and abnormal motility group] by 2.0 ml of Ham's F-10 medium and 1.0 ml of semen. After total DNA extraction, a long-range polymerase chain reaction [PCR] technique was used to determine the mtDNA deletions in human spermatozoa. The products of PCR analysis showed a common 4977 bp deletion and a novel 4866 bp deletion [flanked by a seven-nucleotide direct repeat of 5'-ACCCCCT-3' within the deleted area] from the mtDNA of spermatozoa in both groups. However, the frequency of mtDNA deletions in abnormal motility group was significantly higher than the normal motility group [56, and 24% for 4866 bp-deleted mtDNA and, 52, and 28% for 4977 bp-deleted mtDNA, respectively]. It is suggested that large-scale deletions of the mtDNA is associated with poor sperm motility and may be a causative factor in the decline of fertility in men

Lipid peroxidation and large-scale deletions of mitochondrial DNA in asthenoteratozoospermic patients.

The correlation between malondialdehyde (MDA) an index of lipid peroxidation (LPO) with large-scale deletion mitochondrial DNA (mtDNA) was investigated in a case-control study with a total of 50 semen samples from infertile men, including 25 normozoospermic donor as the control group and 25 asthenoteratozoospermic (AT) patients as the case group. Routine semen analysis was performed according to World Health Organization (WHO, 1999) guidelines. MDA levels of the seminal plasma and spermatozoa were measured by TBARS method. A long-range polymerase chain reaction (PCR) method was used for the analysis of multiple large-scale mtDNA deletions based in two areas of mtDNA. The results showed that mean concentration of MDA in seminal plasma (nmol/ml) and spermatozoa (nmol/10 × 106 sperm) of AT men was higher than in normozoospermic patients, but the differences were not statistically significant. The products of PCR analysis showed multiple deletions of ~4.7, 4.8, 7.2, 7.3 and 7.4-kb in mtDNA of the spermatozoa in both AT and control groups. Multiple deletions were also observed in 64% of AT patients and 44% of the control group. Moreover, MDA level of the spermatozoa in deleted mtDNA samples group was significantly higher than in non-deleted mtDNA group (p = 0.01). Our findings indicated a positive correlation between increased MDA levels and large-scale mtDNA deletions in human spermatozoa. It is suggested that LPO or other oxidative stress factors might be causative elements in mtDNA damage, effect on sperm motility and morphology, resulting in decline of fertility in men.