Effects of airport screening X-irradiation on bovine sperm chromatin integrity and embryo development K.E.M. Hendricks a , L.M. Penfold b, * , D.P. Evenson c , M.T. Kaproth d,e , P.J. Hansen a a Department of Animal Sciences, University of Florida, Gainesville, Florida, USA b White Oak Conservation Center, Yulee, Florida, USA c SCSA Diagnostics, Brookings, South Dakota, USA d Genex Cooperative, Ithaca, New York, USA e Department of Animal Science, Cornell University, Ithaca, New York, USA Received 11 May 2009; received in revised form 25 August 2009; accepted 7 September 2009 Abstract Biological samples, including cryopreserved sperm, are routinely X-rayed during air shipment. The goal was to investigate the impact of X-irradiation used for checked and carry-on luggage on bovine sperm chromatin integrity and postfertilization in vitro embryonic development. Frozen domestic bull sperm (Bos taurus) (n = 9 bulls) stored in a dry shipper (160 8C) was screened by X-irradiation 0, 1, 2, and 3 times as either carry-on or checked luggage. Duplicate straws were thawed, and sperm were assessed for chromatin damage using the sperm chromatin structure assay (SCSA) and by postfertilization in vitro developmental competence of mature oocytes. Multiple exposure to X-rays did not significantly affect sperm chromatin integrity assessed by SCSA. There were lower proportions of oocytes cleaved (P = 0.07; 21.6 3.1% vs. 29.4 3.1%, 24.9 3.1%, and 25.7 3.3% for 3 vs. 0, 1, and 2 times, respectively; least-squares means SEM) and that developed to blastocysts (P = 0.06; 9.0 1.7% vs. 13.8 1.7%, 11.5 1.7%, and 12.6 1.9%, respectively) when fertilization was performed with sperm X-rayed 3 times using checked luggage irradiation; developmental competence (percentage cleaved embryos becoming blastocysts) was unaffected. There were no deleterious effects of other X-irradiation treatments on embryo development. We inferred that screening by X-irradiation may reduce the ability of sperm to activate oocyte cleavage after multiple exposures at the checked luggage dose. However, there was no evidence that competence of embryos to become blastocysts was reduced by X-irradiation (45.4 5.7%, 40.4 5.7%, 46.4 6.1%, and 41.8 5.7% for 0, 1, 2, and 3 doses, respectively), but potential long-term epigenetic effects are unknown. # 2010 Published by Elsevier Inc. Keywords: Bovine; Embryo; Fertilization; SCSA; Spermatozoa; X-irradiation 1. Introduction Air transportation of biological material such as sperm, ova, and embryos has become common with the advent of assisted reproductive technologies. These biological materials are exposed to X-irradiation at ports of entry and exit. It is not known whether the levels of X-irradiation employed at airport security check- points adversely affect bovine sperm chromatin or affect sperm potential fertilizing ability and embryo development rates, although in a previous study, DNA in domestic cat spermatozoa was negatively affected by exposure to multiple doses of X-rays through airport screening devices [1]. It is noteworthy that X-irradiation has been shown to cause DNA strand breaks and www.theriojournal.com Available online at www.sciencedirect.com Theriogenology 73 (2010) 267–272 * Corresponding author. Tel.: +1 904 225 3382; fax: +1 904 225 3337. E-mail address: Lindap@wogilman.com (L.M. Penfold). 0093-691X/$ – see front matter # 2010 Published by Elsevier Inc. doi:10.1016/j.theriogenology.2009.09.009