title: Characterisation of a subpopulation of sperm with massive nuclear damage, as recognised with the sperm chromatin dispersion test.
abstract: Assessment of human sperm DNA fragmentation by the sperm chromatin dispersion (SCD) test is based on the detection of haloes of spreading DNA loops after sequential DNA denaturing and protamine removal. After the SCD test, sperm without DNA fragmentation show chromatin haloes emerging from the central nuclear core, while sperm containing fragmented DNA present small or no haloes. The nuclear degraded sperm are recognised as a differentiated category within the sperm with fragmented DNA, whose cores appear irregularly and/or faintly stained. This subpopulation is more prevalent in patients with varicocele. Protein staining with 2.7-dibrom-4-hydroxy-mercury-fluorescein demonstrated that degraded sperm intensely lose nuclear core proteins after the SCD processing. Moreover, degraded sperm are 65% more faintly labelled for DNA breaks after in situ nick translation (ISNT) on average, due to extensive DNA loss. A two-dimensional comet assay under sequential neutral and alkaline conditions demonstrated that degraded sperm contain both massive double- and single-strand DNA breaks. The degraded sperm appear as a subpopulation with stronger nuclear damage, affecting both DNA and protein fractions, possibly due to intense intratesticular oxidative stress, what could explain its higher proportion in patients with varicocele.
authors.affiliation: Department of Biology, Genetics Unit, Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Gosálvez
authors.forename: M
authors.initials: M
authors.lastname: Rodríguez-Predreira
authors.forename: A
authors.initials: A
authors.lastname: Mosquera
authors.forename: C
authors.initials: C
authors.lastname: López-Fernández
authors.forename: S C
authors.initials: SC
authors.lastname: Esteves
authors.forename: A
authors.initials: A
authors.lastname: Agarwal
authors.forename: J L
authors.initials: JL
authors.lastname: Fernández
mesh_terms: D016022:Case-Control Studies; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002843:Chromatin / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020552:Comet Assay / Q000379:methods; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D053938:DNA Fragmentation; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D009687:Nuclear Proteins / Q000378:metabolism; D018384:Oxidative Stress; D013094:Spermatozoa / Q000145:classification / Q000378:metabolism* / Q000473:pathology*; D014646:Varicocele / Q000235:genetics / Q000378:metabolism / Q000473:pathology
chemical_list: D002843:Chromatin; D009687:Nuclear Proteins
keywords: Degraded sperm; sperm DNA fragmentation; sperm chromatin dispersion test; sperm subpopulation; varicocele