title: Mild oxidative stress is beneficial for sperm telomere length maintenance.
abstract: OBJECTIVE
  To evaluate telomere length in sperm DNA and its correlation with oxidative stress (normal, mild, severe).
  
  
  METHODS
  The study included infertile men (n = 112) and age matched fertile controls (n = 102). The average telomere length from the sperm DNA was measured using a quantitative real time PCR based assay. Seminal reactive oxygen species (ROS) and 8-Isoprostane (8-IP) levels were measured by chemiluminescence assay and ELISA respectively.
  
  
  RESULTS
  Average sperm telomere length in infertile men and controls was 0.609 ± 0.15 and 0.789 ± 0.060, respectively (P < 0.0001). Seminal ROS levels in infertile was higher [66.61 ± 28.32 relative light units (RLU)/s/million sperm] than in controls (14.04 ± 10.67 RLU/s/million sperm) (P < 0.0001). The 8-IP level in infertile men was significantly higher (421.55 ± 131.29 pg/mL) than in controls (275.94 ± 48.13 pg/mL) (P < 0.001). When correlated to oxidative stress, in normal range of oxidative stress (ROS, 0-21.3 RLU/s/million sperm) the average telomere length in cases was 0.663 ± 0.14, in mild oxidative stress (ROS, 21.3-35 RLU/s/million sperm) it was elevated (0.684 ± 0.12) and in severe oxidative stress (ROS > 35 RLU/s/million sperm) average telomere length was decreased to 0.595 ± 0.15.
  
  
  CONCLUSIONS
  Mild oxidative stress results in lengthening of telomere length, but severe oxidative stress results in shorter telomeres. Although telomere maintenance is a complex trait, the study shows that mild oxidative stress is beneficial in telomere length maintenance and thus a delicate balance needs to be established to maximize the beneficial effects of free radicals and prevent harmful effects of supra physiological levels. Detailed molecular evaluation of telomere structure, its correlation with oxidative stress would aid in elucidating the cause of accelerated telomere length attrition.
authors.affiliation: Swetasmita Mishra, Rima Dada, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Swetasmita
authors.initials: S
authors.lastname: Mishra
authors.affiliation: Swetasmita Mishra, Rima Dada, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Swetasmita Mishra, Rima Dada, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Neena
authors.initials: N
authors.lastname: Malhotra
authors.affiliation: Swetasmita Mishra, Rima Dada, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Neeta
authors.initials: N
authors.lastname: Singh
authors.affiliation: Swetasmita Mishra, Rima Dada, Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Rima
authors.initials: R
authors.lastname: Dada
keywords: 8-Isoprostane; Infertility; Oxidative stress; Reactive oxygen species; Telomere