Quality mark
A group of researchers from the University of Massachusetts at Amherst has discovered a way to more accurately diagnose male infertility. They identified a biomarker in spermatozoa that can characterize male reproductive health and the likelihood of a couple's pregnancy.
The discovery applies not only to couples seeking help for infertility, but also to the general population. This biomarker may become a more accurate indicator of male infertility than the sperm parameters that are used today.
The clinical diagnosis of male infertility has not changed in recent decades, despite the great strides made over the years in understanding the molecular and cellular functions of spermatozoa.
Richard Pilzner's group from the University of Massachusetts collaborated with reproductive and perinatal epidemiologist Germaine Buck Louis from George Mason University, as well as Sunny Mumford and Enrique Schisterman from the National Institute of Child Health and Human Development.
Mitochondrial DNA (mtDNA) is inherited through the maternal line, and the number of copies of mtDNA of spermatozoa (mtDNA copies) during spermatogenesis is usually reduced by eight to ten times so that it is low enough during fertilization. In a previous study conducted by Pilzner and colleagues, it was shown that an increase in the number of mtDNA copies and mitochondrial DNA deletions (mtDNA deletions) was associated with a decrease in sperm quality in men and a lower probability of fertilization in couples who applied for infertility treatment.
Therefore, the next logical step was to determine whether it was possible to transfer the relationship between mitochondrial biomarkers of sperm and fertilization among couples who applied for infertility treatment to couples from the general population. To do this, the researchers used sperm samples from the Longitudinal Investigation of Fertility and the Environment (LIFE) study, in which 501 couples from Michigan and Texas participated from 2005 to 2009, to assess the relationship between lifestyle and human fertility.
The researchers identified mtDNA copies and mtDNA deletions in 384 sperm samples and analyzed their relationship with the probability of a partner's pregnancy within one year. They found that men with a higher content of mtDNA copies in spermatozoa were 50% more likely to become pregnant with a partner in a certain phase of the cycle, and the probability of pregnancy within 12 months was 18% lower.
It was noteworthy that there was a strong feedback between the mitochondrial biomarkers of spermatozoa and the time of pregnancy.
The results of the study suggest that mitochondrial DNA in spermatozoa reflects some important physiological processes that affect sperm function.
To further study the effect of changes in the number of mtDNA copies and mtDNA deletions, which may be the result of defective mitochondria or damaged mtDNA, additional studies are needed.
The authors plan to continue their work and study the factors mediating changes in the mitochondrial DNA of spermatozoa. They suggest that such factors include environmental toxins, chronic inflammation and oxidative stress. Understanding the reasons for maintaining the number of copies of mitochondrial DNA during spermatogenesis will help scientists create intervention methods to ensure reproductive success.
Article by A.J.Rosati et al. Sperm mitochondrial DNA biomarkers and couple fecundity is published in the journal Human Reproduction.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on UMass Amherst: Research Identifies Sperm Biomarker Associated with Couples' Pregnancy Probability.