Molecular Effects of Environmental Pollutants on Sperm Chromatin Dynamics

Environmental contaminants such as heavy metals, organic compounds and airborne particulates exert deleterious effects on male reproductive health by disrupting the specialised packaging of sperm chromatin. In mature spermatozoa, canonical histones are largely replaced by protamines to achieve a compact, transcriptionally silent state that protects the paternal genome. Pollutant-driven oxidative stress, aberrant metal binding and enzymatic modifications can alter the protamine/histone ratio, induce DNA strand breaks and compromise chromatin compaction. These molecular disturbances not only impair fertilisation potential but may also drive epigenetic changes transmissible to the next generation. Recent work has begun to characterise how specific pollutants perturb nucleoprotein interactions, modulate small-RNA profiles and activate chromatin-remodelling enzymes, shedding light on global fertility declines and informing both public health measures and potential dietary or pharmacological interventions.

Research from Nature Portfolio

One foundational study uncovered that copper ions, in the presence of hydrogen peroxide, selectively target arginine residues in sperm-specific H1 histones. This interaction promotes DNA breakage, enhances histone resistance to proteolysis and drives a reorganisation of histone side-chains, thereby altering chromatin architecture. By demonstrating how redox-active metals can directly remodel nucleoproteins, these findings provide a mechanistic link between environmental copper exposure and destabilisation of sperm chromatin integrity.

Molecular Effects of Environmental Pollutants on Sperm Chromatin Dynamics publication trend

The graph below shows the total number of articles in molecular effects of environmental pollutants on sperm chromatin dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Chromatin: The complex of DNA and associated proteins that compacts genomic material within the nucleus.

Protamine: Small, arginine-rich basic proteins that replace histones during spermiogenesis to achieve high-order DNA condensation.

Histone: Core nuclear proteins around which DNA winds to form nucleosomes in most somatic cells.

Epigenetic modification: Chemical alterations to DNA or histones that affect gene expression without changing the DNA sequence.

Piwi-interacting RNA (piRNA): A class of small noncoding RNAs that regulate transposon activity and germ cell development.

Micrococcal nuclease: An endonuclease that preferentially digests accessible regions of chromatin, used to assess nucleoprotein compaction.

References

1. Small noncoding RNAs and sperm nuclear basic proteins reflect the environmental impact on germ cells. Molecular Medicine (2024).
2. Molecular and toxicological mechanisms behind the effects of chromium (VI) on the male reproductive system of Mytilus galloprovincialis: First evidence for poly-ADP-ribosylation of protamine-like II. Chemico-Biological Interactions (2024).
3. Relevance of arginine residues in Cu(II)-induced DNA breakage and Proteinase K resistance of H1 histones. Scientific Reports (2018).