Register      Login
Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology
RESEARCH ARTICLE

Reduced glutathione and procaine hydrochloride protect the nucleoprotein structure of boar spermatozoa during freeze–thawing by stabilising disulfide bonds

Marc Yeste A C , Eva Flores B , Efrén Estrada A , Sergi Bonet B , Teresa Rigau A and Joan E. Rodríguez-Gil A
+ Author Affiliations
- Author Affiliations

A Unit of Animal Reproduction, Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain.

B Biotechnology of Animal and Human Reproduction (TechnoSperm), Department of Biology, Institute of Food and Agricultural Technology, University of Girona, 17071 Girona, Spain.

C Corresponding author. Email: marc.yeste@uab.cat

Reproduction, Fertility and Development 25(7) 1036-1050 https://doi.org/10.1071/RD12230
Submitted: 13 February 2012  Accepted: 25 September 2012   Published: 23 October 2012

Abstract

One important change the head of boar spermatozoa during freeze–thawing is the destabilisation of its nucleoprotein structure due to a disruption of disulfide bonds. With the aim of better understanding these changes in frozen–thawed spermatozoa, two agents, namely reduced glutathione (GSH) and procaine hydrochloride (ProHCl), were added at different concentrations to the freezing media at different concentrations and combinations over the range 1–2 mM. Then, 30 and 240 min after thawing, cysteine-free residue levels of boar sperm nucleoproteins, DNA fragmentation and other sperm functional parameters were evaluated. Both GSH and ProHCl, at final concentrations of 2 mM, induced a significant (P < 0.05) increase in the number of non-disrupted sperm head disulfide bonds 30 and 240 min after thawing compared with the frozen–thawed control. This effect was accompanied by a significant (P < 0.05) decrease in DNA fragmentation 240 min after thawing. Concomitantly, 1 and 2 mM GSH, but not ProHCl at any of the concentrations tested, partially counteracted the detrimental effects caused by freeze–thawing on sperm peroxide levels, motility patterns and plasma membrane integrity. In conclusion, the results show that both GSH and ProHCl have a stabilising effect on the nucleoprotein structure of frozen–thawed spermatozoa, although only GSH exerts an appreciable effect on sperm viability.

Additional keywords : sperm cryopreservation.


References

Agarwal, A., and Said, T. M. (2003). Role of sperm chromatin abnormalities and DNA damage in male infertility. Hum. Reprod. Update 9, 331–345.
Role of sperm chromatin abnormalities and DNA damage in male infertility.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXlsFyhu7g%3D&md5=64158741e8684fc39861e206b10eef2bCAS | 12926527PubMed |

Aitken, R. J. (1995). Free radicals, lipid peroxidation and sperm function. Reprod. Fertil. Dev. 7, 659–668.
Free radicals, lipid peroxidation and sperm function.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK28Xht1Clsrw%3D&md5=ac49437b5e76110a00774d03f293de9dCAS | 8711202PubMed |

Awda, B. J., Mackenzie-Bell, M., and Buhr, M. M. (2009). Reactive oxygen species and boar sperm function. Biol. Reprod. 81, 553–561.
Reactive oxygen species and boar sperm function.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhtVChu7zP&md5=baa7dc0d7fc48d8eaf441a0da27f9f90CAS | 19357363PubMed |

Balhorn, R. (2007). The protamine family of sperm nuclear proteins. Genome Biol. 8, 227–238.
The protamine family of sperm nuclear proteins.Crossref | GoogleScholarGoogle Scholar | 17903313PubMed |

Ball, B. A., Vo, A. T., and Baumber, J. (2001). Generation of reactive oxygen species by equine spermatozoa. Am. J. Vet. Res. 62, 508–515.
Generation of reactive oxygen species by equine spermatozoa.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXjtVWhsrY%3D&md5=c79337d75fde3001c4402cf8a95017aaCAS | 11327456PubMed |

Baumber, J., Ball, B. A., Linfor, J. J., and Meyers, S. A. (2003). Reactive oxygen species and cryopreservation promote DNA fragmentation in equine spermatozoa. J. Androl. 24, 621–628.
| 1:CAS:528:DC%2BD2cXjtl2itb0%3D&md5=b80b8ccb7d451422ae79a1141ab24b6fCAS | 12826702PubMed |

Bilodeau, J. F., Chatterjee, S., Sirard, M. A., and Gagnon, C. (2000). Level of antioxidant defenses are decreased in bovine spermatozoa after a cycle of freezing and thawing. Mol. Reprod. Dev. 55, 282–288.
Level of antioxidant defenses are decreased in bovine spermatozoa after a cycle of freezing and thawing.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXhtFeltr8%3D&md5=5a548d5543467816d47f7ed591562ee9CAS | 10657047PubMed |

Boe-Hansen, G. B., Ersboll, A. K., Grever, T., and Christensen, P. (2005). Increasing storage time of extended boar semen reduces sperm DNA integrity. Theriogenology 63, 2006–2019.
Increasing storage time of extended boar semen reduces sperm DNA integrity.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXjt1Kjtbs%3D&md5=940abb50430cfc0ec8af7cb957ede2d7CAS | 15823356PubMed |

Bradford, M. M. (1976). A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72, 248–254.
A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaE28XksVehtrY%3D&md5=a7b3d941b2d4571e1bf03cdd05e3fd69CAS | 942051PubMed |

Brewer, L., Corzett, M., Lau, E. Y., and Balhorn, R. (2003). Dynamics of protamine-1 binding to single DNA molecules. J. Biol. Chem. 278, 42 403–42 408.
Dynamics of protamine-1 binding to single DNA molecules.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXot1amu7c%3D&md5=ec63491c6d514f0d0a2d452c895009e4CAS |

Brocklehurst, K., Stuchbury, T., and Malthouse, J. P. G. (1979). Reactivities of neutral and cationic forms of 2,2-dipyridyl disulphide towards thiolate anions: detection of differences between the active centres of actinidin, papain and ficin by a three-protonic-state reactivity probe. Biochem. J. 183, 233–238.
| 1:CAS:528:DyaL3cXhtVKnur8%3D&md5=d954eee09fd99a10a24370c47738fc7fCAS |

Casas, I., Sancho, S., Briz, M., Pinart, E., Bussalleu, E., Yeste, M., and Bonet, S. (2009). Freezability prediction of boar ejaculates assessed by functional sperm parameters and sperm proteins. Theriogenology 72, 930–948.
Freezability prediction of boar ejaculates assessed by functional sperm parameters and sperm proteins.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhtFGlsr3E&md5=cb921d94176a753cb4a0458fc6565cd2CAS | 19651432PubMed |

Casas, I., Sancho, S., Briz, M., Pinart, E., Bussalleu, E., Yeste, M., and Bonet, S. (2010). Fertility after post-cervical artificial insemination with cryopreserved sperm from boar ejaculates of good and poor freezability. Anim. Reprod. Sci. 118, 69–76.
Fertility after post-cervical artificial insemination with cryopreserved sperm from boar ejaculates of good and poor freezability.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD1MfhsFyltw%3D%3D&md5=aa94b2ef3c6103187c14d773ad99f4c9CAS | 19577868PubMed |

Chapman, J. C., and Michael, S. D. (2003). Proposed mechanism for sperm chromatin condensation/decondensation in the male rat. Reprod. Biol. Endocrinol. 1, 20.
Proposed mechanism for sperm chromatin condensation/decondensation in the male rat.Crossref | GoogleScholarGoogle Scholar | 12646056PubMed |

Chatterjee, S., De Lamirande, E., and Gagnon, C. (2001). Cryopreservation alters membrane sulfhydryl status of bull spermatozoa: protection by oxidized glutathione. Mol. Reprod. Dev. 60, 498–506.
Cryopreservation alters membrane sulfhydryl status of bull spermatozoa: protection by oxidized glutathione.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3MXosl2qt70%3D&md5=52c3f0be8408c2e29412cc2dac4f3e38CAS | 11746961PubMed |

Cumming, R. C., Andon, N. L., Haynes, P. A., Park, M., Fischer, W. H., and Schubert, D. (2004). Protein disulphide bond formation in the cytoplasm during oxidative stress. J. Biol. Chem. 279, 21 749–21 758.
Protein disulphide bond formation in the cytoplasm during oxidative stress.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXjvF2ktb0%3D&md5=f0b080fac1669164a1580ba80c20ed9cCAS |

De Lamirande, E., and Gagnon, C. (1992). Reactive oxygen species and human spermatozoa II: depletion of adenosine triphosphate plays an important role in the inhibition of sperm motility. J. Androl. 13, 379–386.
| 1:CAS:528:DyaK3sXkslSi&md5=8330b62ded6eda5afcc0714f3a205f46CAS | 1331007PubMed |

Didion, B. A., Kasperson, K. M., Wixon, R. L., and Evenson, D. P. (2009). Boar fertility and sperm chromatin structure status: a retrospective report. J. Androl. 30, 655–660.
Boar fertility and sperm chromatin structure status: a retrospective report.Crossref | GoogleScholarGoogle Scholar | 19478334PubMed |

Enciso, M., López-Fernández, C., Fernández, J. L., García, P., Gosálvez, A. I., and Gosálvez, J. (2006). A new method to analyze boar sperm DNA fragmentation under bright-field or fluoresecence microscopy. Theriogenology 65, 308–316.
A new method to analyze boar sperm DNA fragmentation under bright-field or fluoresecence microscopy.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXhtlCqtb%2FO&md5=48e652eab548a0b78dd4a89842cbbe5fCAS | 15996725PubMed |

Evenson, D. P., Jost, L. K., Marshall, D., Zinaman, M. J., Clegg, E., Purvis, K., de Angelis, P., and Claussen, O. P. (1999). Utility of the sperm chromatin structure assay as a diagnostic and prognostic tool in the human fertility clinic. Hum. Reprod. 14, 1039–1049.
Utility of the sperm chromatin structure assay as a diagnostic and prognostic tool in the human fertility clinic.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DyaK1M3jslGqtA%3D%3D&md5=21f6e4a7bb6dd56b71a152f4c30c68afCAS | 10221239PubMed |

Fatehi, A. N., Bevers, M. M., Schoevers, E., Roelen, B. A., Colenbrander, B., and Gadella, B. M. (2006). DNA damage in bovine sperm does not block fertilization and early embryonic development but induces apoptosis after the first cleavages. J. Androl. 27, 176–188.
DNA damage in bovine sperm does not block fertilization and early embryonic development but induces apoptosis after the first cleavages.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xit12jtb0%3D&md5=c33ed34b00a8643e1991124c557c76a4CAS | 16304212PubMed |

Fenoglio, C., Boicelli, C. A., Ottone, M., Addario, C., Chiari, P., and Viale, M. (2002). Protective effect of procaine hydrochloride on cisplatin-induced alterations in rat kidney. Anticancer Drugs 13, 1043–1054.
Protective effect of procaine hydrochloride on cisplatin-induced alterations in rat kidney.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38XoslGls7Y%3D&md5=9f947b068144a8681bfe969f399d811bCAS | 12439338PubMed |

Flores, E., Cifuentes, D., Fernández-Novell, J. M., Medrano, A., Bonet, S., Briz, M. D., Pinart, E., Peña, A., Rigau, T., and Rodríguez-Gil, J. E. (2008). Freeze–thawing induces alterations in the protamine-1/DNA overall structure in boar sperm. Theriogenology 69, 1083–1094.
Freeze–thawing induces alterations in the protamine-1/DNA overall structure in boar sperm.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1cXlvVSltLY%3D&md5=283d3ed7089703d10b23f404b94aad8eCAS | 18359506PubMed |

Flores, E., Ramió-Lluch, L., Bucci, D., Fernández-Novell, J. M., Peña, A., and Rodríguez-Gil, J. E. (2011). Freezing–thawing induces alterations in histone H1-DNA binding and the breaking of protein–DNA disulphide bonds in boar sperm. Theriogenology 76, 1450–1464.
Freezing–thawing induces alterations in histone H1-DNA binding and the breaking of protein–DNA disulphide bonds in boar sperm.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXht12isbjK&md5=8742398999fa08abb390ded5697e19e5CAS | 21855992PubMed |

Fraser, L., and Strezeżek, J. (2005). Effects of freezing–thawing on DNA integrity of boar spermatozoa assessed by the neutral comet assay. Reprod. Domest. Anim. 40, 530–536.
Effects of freezing–thawing on DNA integrity of boar spermatozoa assessed by the neutral comet assay.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD2MnkslWmsA%3D%3D&md5=8f37757a9f4d59f0df91dc8e459707f3CAS | 16324079PubMed |

Fuentes-Mascorro, G., Serrano, H., and Rosado, A. (2000). Sperm chromatin. Arch. Androl. 45, 215–225.
Sperm chromatin.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3cXovVShsbw%3D&md5=70fe9cb4708b8c72f57bf31d37971250CAS | 11111870PubMed |

Gadea, J., Sellés, E., Marco, M. A., Coy, P., Matás, C., Romar, R., and Ruiz, S. (2004). Decrease in glutathione content in boar sperm after cryopreservation. Effect of the addition of reduced glutathione to the freezing and thawing extenders. Theriogenology 62, 690–701.
Decrease in glutathione content in boar sperm after cryopreservation. Effect of the addition of reduced glutathione to the freezing and thawing extenders.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXltF2rs78%3D&md5=724289ab5e6ee1ad419db25ef1582badCAS | 15226023PubMed |

Gadea, J., García-Vázquez, F. A., Matás, C., Gardón, J. C., Cánovas, S., and Gumbao, D. (2005). Cooling and freezing of boar spermatozoa: supplementation of the freezing media with reduced glutathione preserves sperm function. J. Androl. 26, 396–404.
Cooling and freezing of boar spermatozoa: supplementation of the freezing media with reduced glutathione preserves sperm function.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2MXkvVWjsrg%3D&md5=e18b964878773a060e5b3ccfc020da51CAS | 15867008PubMed |

Gadea, J., Molla, M., Sellés, E., Marco, M. A., García-Vázquez, F. A., and Gardón, J. C. (2011). Reduced glutathione content in human sperm is decreased after cryopreservation: effect of the addition of reduced glutathione to the freezing and thawing extenders. Cryobiology 62, 40–46.
Reduced glutathione content in human sperm is decreased after cryopreservation: effect of the addition of reduced glutathione to the freezing and thawing extenders.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXhvVyksLw%3D&md5=0a9abeae22ea44f41a0edc47805e8690CAS | 21156167PubMed |

Garner, D. L., and Johnson, L. A. (1995). Viability assessment of mammalian sperm using SYBR-14 and propidium iodide. Biol. Reprod. 53, 276–284.
Viability assessment of mammalian sperm using SYBR-14 and propidium iodide.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXntVSmtbc%3D&md5=f240eab17d7c24f67b51594a2da738daCAS | 7492679PubMed |

Guthrie, H. D., and Welch, G. R. (2006). Determination of intracellular reactive oxygen species and high mitochondrial membrane potential in Percoll-treated viable boar sperm using fluorescence-activated flow cytometry. J. Anim. Sci. 84, 2089–2100.
Determination of intracellular reactive oxygen species and high mitochondrial membrane potential in Percoll-treated viable boar sperm using fluorescence-activated flow cytometry.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xot1Onur8%3D&md5=09b3e6f2c8ef0309868f8b7cb0768ae2CAS | 16864869PubMed |

Hernández, M., Roca, J., Ballester, J., Vázquez, J. M., Martínez, E. A., Johannisson, A., Saravia, F., and Rodríguez-Martínez, H. (2006). Differences in SCSA outcome among boars with different sperm freezability. Int. J. Androl. 29, 583–591.
Differences in SCSA outcome among boars with different sperm freezability.Crossref | GoogleScholarGoogle Scholar | 17121656PubMed |

Jacob, C., Giles, G. I., Giles, N. M., and Sies, H. (2003). Sulfur and selenium: the role of oxidation state in protein structure and function. Angew. Chem. Int. Ed. 42, 4742–4758.
Sulfur and selenium: the role of oxidation state in protein structure and function.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD3sXosFKntbg%3D&md5=bd51a0c95eecf7dc90c966189855dcfbCAS |

Kim, S. H., Yu, D. H., and Kim, Y. J. (2010). Effects of cryopreservation on phosphatidylserine translocation, intracellular hydrogen peroxide, and DNA integrity in canine sperm. Theriogenology 73, 282–292.
Effects of cryopreservation on phosphatidylserine translocation, intracellular hydrogen peroxide, and DNA integrity in canine sperm.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhs1Wgt7fO&md5=e09af4df41c63338cd6642a50957b0bdCAS | 19883935PubMed |

Kim, S. H., Lee, Y. J., and Kim, Y. J. (2011). Changes in sperm membrane and ROS following cryopreservation of liquid boar semen stored at 15°C. Anim. Reprod. Sci. 124, 118–124.
Changes in sperm membrane and ROS following cryopreservation of liquid boar semen stored at 15°C.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3MXjvVyjsr4%3D&md5=764e1215e1b8639c024b58ea49ae0392CAS |

Lee, J. A., Spidlen, J., Boyce, K., Cai, J., Crosbie, N., Dalphin, M., Furlong, J., Gasparetto, M., Goldberg, M., Goralczykm, E. M., et al. (2008). MIFlowCyt: the minimum information about a flow cytometry experiment. Cytometry A 73A, 926–930.
MIFlowCyt: the minimum information about a flow cytometry experiment.Crossref | GoogleScholarGoogle Scholar |

Lee, J. M., Suh, J. K., Jeong, J. S., Cho, S. Y., and Kim, D. W. (2010). Antioxidant effect of lidocaine and procaine on reactive oxygen species-induced endothelial dysfunction in the rabbit abdominal aorta. Korean J. Anesthesiol. 59, 104–110.
Antioxidant effect of lidocaine and procaine on reactive oxygen species-induced endothelial dysfunction in the rabbit abdominal aorta.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BC3cXhtFOnsr3E&md5=036fd65c5fb4bea36a08599de4e0f26eCAS | 20740215PubMed |

Lopes, S. (1997). DNA fragmentation in spermatozoa: implications for failed fertilization in intracytoplasmic sperm injection. M.Sc. Thesis. Institute of Medical Science, University of Toronto, Canada.

López-Fernández, C., Johnston, S. D., Fernández, J. L., Wilson, R. J., and Gosálvez, J. (2010). Fragmentation dynamics of frozen-thawed ram sperm DNA is modulated by sperm concentration. Theriogenology 74, 1362–1370.
Fragmentation dynamics of frozen-thawed ram sperm DNA is modulated by sperm concentration.Crossref | GoogleScholarGoogle Scholar | 20688370PubMed |

Márquez, B., and Suárez, S. S. (2004). Different signaling pathways in bovine sperm regulate capacitation and hyperactivation. Biol. Reprod. 70, 1626–1633.
Different signaling pathways in bovine sperm regulate capacitation and hyperactivation.Crossref | GoogleScholarGoogle Scholar | 14766720PubMed |

McPartlin, L. A., Suarez, S. S., Czaya, C. A., Hinrichs, K., and Bedford-Guaus, S. J. (2009). Hyperactivation of stallion sperm is required for successful in vitro fertilization of equine oocytes. Biol. Reprod. 81, 199–206.
Hyperactivation of stallion sperm is required for successful in vitro fertilization of equine oocytes.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXnslaqs7w%3D&md5=0b96c378dd59982f9fb1473a2418720cCAS | 19208544PubMed |

Mújica, A., Neri-Bazan, L., Tash, J. S., and Uribe, S. (1994). Mechanism for procaine-mediated hyperactivated motility in guinea pig spermatozoa. Mol. Reprod. Dev. 38, 285–292.
Mechanism for procaine-mediated hyperactivated motility in guinea pig spermatozoa.Crossref | GoogleScholarGoogle Scholar | 7917280PubMed |

Nasr-Esfahani, M. H., Razavi, S., Mozdarani, H., Mardani, M., and Azvagi, H. (2004). Relationship between protamine deficiency with fertilization rate and incidence of sperm premature chromosomal condensation post-ICSI. Andrologia 36, 95–100.
Relationship between protamine deficiency with fertilization rate and incidence of sperm premature chromosomal condensation post-ICSI.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXms1ymsro%3D&md5=fd1b3719c76dd7e1f6d368c606666128CAS | 15206907PubMed |

Oliva, R. (2006). Protamines and male infertility. Hum. Reprod. Update 12, 417–435.
Protamines and male infertility.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD28Xmt1Wktbc%3D&md5=be9edd169045b2033ed7ff1e37a23c02CAS | 16581810PubMed |

Petrunkina, A. M., and Harrison, R. A. P. (2010). Systematic misestimation of cell subpopulations by flow cytometry: a mathematical analysis. Theriogenology 73, 839–847.
Systematic misestimation of cell subpopulations by flow cytometry: a mathematical analysis.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC3c3gtlKlsw%3D%3D&md5=af1049ce519bf68c44e3cbb4fc22c3ddCAS | 19896183PubMed |

Petrunkina, A. M., Waberski, D., Bollwein, H., and Sieme, H. (2010). Identifying non-sperm particles during flow cytometric physiological assessment: a simple approach. Theriogenology 73, 995–1000.
Identifying non-sperm particles during flow cytometric physiological assessment: a simple approach.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC3c3gsVejtQ%3D%3D&md5=047b861fead73a5576cdd13d7629bc1aCAS | 20171719PubMed |

Ping, G., Lv, G., Gutmann, S., Chen, C., Zhang, R., and Wang, X. (2006). Study on the binding of procaine hydrochloride to DNA/DNA bases and the effect of CdS nanoparticles on the binding behavior. J. Nanosci. Nanotechnol. 6, 91–94.
| 1:CAS:528:DC%2BD28XisFaguro%3D&md5=b47ecfc7b4d5a7d62aeb471dd5a13282CAS | 16573076PubMed |

Rybar, R., Faldikova, L., Faldyna, M., Machatkova, M., and Rubes, J. (2004). Bull and boar sperm DNA integrity evaluated by sperm chromatin structure assay in the Czech Republic. Vet. Med. Czech. 49, 1–8.
| 1:CAS:528:DC%2BD2cXjt1Sqt7o%3D&md5=a57c7d1d0d5ebb55cf1d3caf5bcbc20dCAS |

Sakkas, D., Urner, F., Bizzaro, D., Manicardi, G., Bianchi, P. G., Shoukir, Y., and Campana, A. (1998). Sperm nuclear DNA damage and altered chromatin structure: effect on fertilization and embryo development. Hum. Reprod. 13, 11–19.
Sperm nuclear DNA damage and altered chromatin structure: effect on fertilization and embryo development.Crossref | GoogleScholarGoogle Scholar | 10091054PubMed |

Sikka, S. C. (2001). Relative impact of oxidative stress on male reproductive function. Curr. Med. Chem. 8, 851–862.
| 1:CAS:528:DC%2BD3MXjsVChuro%3D&md5=a8004d96b5a0157ab3a3942fadb74cadCAS | 11375755PubMed |

Silva, P. F. N., and Gadella, B. M. (2006). Detection of damage in mammalian sperm cells. Theriogenology 65, 958–978.
Detection of damage in mammalian sperm cells.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD283gtlKqtg%3D%3D&md5=0e5da9bb5ec7ec38dbefeffa74ce18a7CAS |

Sotolongo, B., Huang, T. T., Isenberger, E., and Ward, W. S. (2005). An endogenous nuclease in hamster, mouse, and human spermatozoa cleaves DNA into loop-sized fragments. J. Androl. 26, 272–280.
| 1:CAS:528:DC%2BD2MXis1Slu7s%3D&md5=463f56cab93662ef01d6f27c2b898805CAS | 15713834PubMed |

Stenesh, J. (1998). ‘Biochemistry.’ (Plenum Press: New York.)

Tesarik, J., Greco, E., and Mendoza, C. (2004). Late, but not early, paternal effect on human embryo development is related to sperm DNA fragmentation. Hum. Reprod. 19, 611–615.
Late, but not early, paternal effect on human embryo development is related to sperm DNA fragmentation.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXhvFSqtrc%3D&md5=21d2431e3fa273d1eb8e9b5a6f5bf222CAS | 14998960PubMed |

Tsakmakidis, A., Lymberopoulos, A. G., and Khalifa, T. A. A. (2010). Relationship between sperm quality traits and field-fertility of porcine semen. J. Vet. Sci. 11, 151–154.
Relationship between sperm quality traits and field-fertility of porcine semen.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC3czisFyqtA%3D%3D&md5=e4233ed7fe3bcb175fb9192eed595e7aCAS |

Watson, P. F. (2000). The causes of reduced fertility with cryopreserved semen. Anim. Reprod. Sci. 60–61, 481–492.
The causes of reduced fertility with cryopreserved semen.Crossref | GoogleScholarGoogle Scholar | 10844218PubMed |

Ward, M. A., and Ward, W. S. (2004). A model for the function of sperm DNA degradation. Reprod. Fertil. Dev. 16, 547–554.
A model for the function of sperm DNA degradation.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2cXlvVensLw%3D&md5=49859d38022696d234589ea11d4871aaCAS | 15355763PubMed |

Westendorf, P., Richter, L., and Treu, H. (1975). Zur Tiefgefrierung von Ebersperma. Labor-und Besamungsergebnisse mit dem Hülsenberger Pailetten-Verfahren. Dtsch. Tierarztl. Wochenschr. 82, 261–267.
| 1:STN:280:DyaE28%2FmsFyntg%3D%3D&md5=1f8b0e6f8ee6b25039c7b3beeca3f0f8CAS | 1104331PubMed |

Yang, Y., Song, Y., and Loscalzo, J. (2007). Regulation of the protein disulphide proteome by mitochondria in mammalian cells. Proc. Natl Acad. Sci. USA 104, 10 813–10 817.
Regulation of the protein disulphide proteome by mitochondria in mammalian cells.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXnsV2ltbg%3D&md5=c5cf6be68d28035b4794a9e191e47646CAS |

Zhang, J. G., Zhong, L. F., Zhang, M., and Xia, Y. X. (1992). Protection effects of procaine on oxidative stress and toxicities of renal cortical slices from rats caused by cisplatin in vitro. Arch. Toxicol. 66, 354–358.
Protection effects of procaine on oxidative stress and toxicities of renal cortical slices from rats caused by cisplatin in vitro.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK38XmtVGitbo%3D&md5=6c56e69d76e1fcd20796ea7890bf3b70CAS | 1610298PubMed |