Effect of sperm cryopreservation on sperm DNA stability and progeny development in rainbow trout

Abstract

This study was carried out to test how sperm cryopreservation affected nuclear DNA stability and whether progeny development was modified when eggs were fertilized with cryopreserved spermatozoa. The "comet assay" (alkaline single-cell gel electrophoresis assay) was adapted to trout spermatozoa to estimate DNA stability as measured by alkali-induced DNA strand break formation. Because trout eggs develop in water after fertilization (oviparous species) and that eggshell is easy to clear up after fixative treatment, progeny development was assessed from the blastodisc flattening stage of the embryos to the first feeding stage of the hatched fries by direct observation. All parameters under study were analyzed on each sperm and comparisons between parameters were made using paired data. Freeze-thawing of sperm slightly but significantly increased the percentage of nuclei showing altered DNA after comet assay. This increase was correlated to the decrease in fertilization rates of sperm, but the absolute percentage of altered nuclei was not predictive of the absolute fertilization ability of sperm. Assessment of progeny development showed that survival rate and abnormality rate obtained after fertilization with cryopreserved sperm were not different from those obtained with fresh sperm. It is concluded that trout sperm cryopreservation only slightly affected sperm DNA stability and that the use of cryopreserved spermatozoa did not impair offspring survival and quality.

Effects of Cryopreservation on Sperm DNA Integrity in Normospermic and Four Categories of Infertile Males

“…Steel et al [2000] found no appreciable difference in the percentage of comet head DNA of fresh (81.7 AE 1.2%) and frozen-thawed (81.9 AE 2.8%) testicular sperm in contrast to recent studies that showed an increased percentage of DNA fragmentation in cryopreserved sperm samples from human [Donnelly et al 2001a[Donnelly et al , 2001bLabbe et al 2001;Thomson et al 2009]. Furthermore, results from equine [Linfor and Meyers 2002] and rhesus macaques [Li et al 2007] have revealed significantly higher sperm DNA damage in the absence of cryoprotectants prior to freezing.…”

Sperm DNA damage in male infertility: etiologies, assays, and outcomes

“…These causes are many and range from environmental conditions such as cigarette smoking [99], irradiation [8], and chemotherapy [20,88] to pathophysiologic conditions such as leukocytospermia [5,35], varicoceles [105,107], and cancer [70]. Even iatrogenic causes such as sperm cryopreservation [32,73] have been associated with sperm DNA damage. Exact molecular mechanisms by which these conditions lead to sperm DNA damage and/or chromatin abnormalities are not fully understood, but there are currently three main theories which we will review: 1) chromatin packaging abnormalities, 2) reactive oxygen species, and 3) apoptosis.…”

DNA fragmentation and membrane damage of bocachico Prochilodus magdalenae (Ostariophysi: Prochilodontidae) sperm following cryopreservation with dimethylsulfoxide and glucose

“…Some authors mention three possible factors which may cause DNA damage sperm during cryopreservation: i) direct damage of the sperm genome by the possible development of intracellular ice, which can act similarly to gamma radiation upon the DNA fragmentation (Miskolczi et al, 2005), ii) direct damage of the sperm genome by a type of oxygen reactant released by the dead cells or damaged during the freezing or thawing processes (Labbé et al, 2001) and, iii) induction of apoptotic processes on part of the cryopreservation (Cabrita et al, 2010). The factors (i) and (iii) possibly also involved in the damages to the sperm's plasmatic membrane.…”