Response: Nitroblue tetrazolium (NBT) assay

The impact of mitochondrial impairments on sperm function and male fertility: a systematic review

BACKGROUND

Besides adenine triphosphate (ATP) production for sustaining motility, the mitochondria of sperm also host other critical cellular functions during germ cell development and fertilization including calcium homeostasis, generation of reactive oxygen species (ROS), apoptosis, and in some cases steroid hormone biosynthesis. Normal mitochondrial membrane potential with optimal mitochondrial performance is essential for sperm motility, capacitation, acrosome reaction, and DNA integrity.

RESULTS

Defects in the sperm mitochondrial function can severely harm the fertility potential of males. The role of sperm mitochondria in fertilization and its final fate after fertilization is still controversial. Here, we review the current knowledge on human sperm mitochondria characteristics and their physiological and pathological conditions, paying special attention to improvements in assistant reproductive technology and available treatments to ameliorate male infertility.

CONCLUSION

Although mitochondrial variants associated with male infertility have potential clinical use, research is limited. Further understanding is needed to determine how these characteristics lead to adverse pregnancy outcomes and affect male fertility potential.

Transcriptome analysis of the effects of different carbon dioxide concentrations on paramylon accumulation in Euglena gracilis Z

Appropriate concentration of carbon dioxide (CO2) will promote algae growth and metabolism. Building upon this finding, the present study investigated the impact of different CO2 concentrations (5% and 20%) on the carbon sequestration capacity of E. gracilis through aeration culturing, employing a combination of physiological analyses and transcriptome analysis. The results demonstrated that under 5% CO2 concentration, the cell density of E. gracilis was 1.79 times higher than that achieved in an air culture condition, and the paramylon content of E. gracilis was found to be 6.18 times higher than that of the air group. Based on transcriptome analysis, the carbon metabolism of E. gracilis was discussed. Significant up-regulation expression of genes associated with carbon synthesis was validated by an increase in paramylon content. This study revealed that under 5% CO2 conditions, E. gracilis exhibited elevated growth rate and enhanced photosynthetic carbon assimilation efficiency.

Interventions to Prevent Sperm DNA Damage Effects on Reproduction

Excessive oxidation and antioxidant imbalance resulting from several conditions may cause sperm DNA damage, which, in turn, affect male fertility, both natural and assisted. Sperm DNA damage transferred to the embryo might also affect the health of offspring. Several conditions associated with excessive oxidative stress are modifiable by the use of specific treatments, lifestyle changes, and averting exposure to environmental/occupational toxicants. Here, we discuss the strategies to reduce sperm DNA damage with a focus on clinical and surgical interventions.

A clinical assay for reactive oxygen species - ready for primetime?

Reactive oxygen species (ROS) have been demonstrated to have damaging effects on human sperm function. The measurement of ROS as an adjunct to traditional semen analysis has clinical relevance as part of the diagnosis of male infertility. The assay best suited to the clinical laboratory environment for detecting ROS generation remains somewhat controversial. A recent report on a multicenter study evaluating the reduction of nitroblue tetrazolium (NBT) to formazan precipitate as an indirect reporter of ROS-generating activity in spermatozoa, seminal plasma and semen has received a critique raising questions as to the sensitivity and specificity of the assay for detecting ROS. The authors of the report argue in response that the assay has validity and yields results that are potentially clinically significant. This dialogue serves to (re)direct readers to the original article and to consider carefully the intent and potential application of the assay, and whether there is sufficient scientific evidence to judiciously support its clinical diagnostic application.