Effect of cryopreservation on motility and progressive motility of bull spermatozoa.

Effect of cryopreservation on motility and progressive motility of bull spermatozoa.

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An association between progressive motility (PM) and spermatozoa fertility competence has been suggested. However, the mechanism that underlies PM is not clear enough. We examined physiological characteristics and fatty acid composition of fresh spermatozoa with high and low PM. Additional analysis of fatty acid composition and structural character...

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... proportion of motile spermatozoa following the freeze-thaw process was lower than in the fresh sample (p < 0.01; Table 2). The proportion of progressively motile spermatozoa also decreased following the freeze-thaw process and was lower than in the fresh sample (p < 0.01). ...
Context 2
... proportion of motile spermatozoa following the freeze-thaw process was lower than in the fresh sample (p < 0.01; Table 2). The proportion of progressively motile spermatozoa also decreased following the freeze-thaw process and was lower than in the fresh sample (p < 0.01). ...

Citations

... Lipid peroxidation leads to disturbances in membrane fluidity and permeability, causing a reduction of motility and a decrease in the sperm ability to interact and fuse with the oocyte [23]. Even though the injury may affect membranes of any cell type, those of sperm are known to be especially susceptible to oxidative damage due to their great content of polyunsaturated fatty acids [24]. In addition, thiol oxidation by ROS affects the activity of some enzymes, and may also lead to alterations on sperm chromatin, as protamines are rich in thiol groups (cysteine residues) [18,25]. ...
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Background The analysis of chromatin integrity has become an important determinant of sperm quality. In frozen-thawed bovine sperm, neither the sequence of post-thaw injury events nor the dynamics of different types of sperm DNA breaks are well understood. The aim of the present work was to describe such sperm degradation aftermath focusing on DNA damage dynamics, and to assess if this parameter can predict pregnancy rates in cattle. Results A total of 75 cryopreserved ejaculates from 25 Holstein bulls were evaluated at two post-thawing periods (0-2 h and 2-4 h), analyzing global and double-stranded DNA damage through alkaline and neutral Comet assays, chromatin deprotamination and decondensation, sperm motility, viability, acrosomal status, and intracellular levels of total ROS, superoxides and calcium. Insemination of 59,605 females was conducted using sperm from the same bulls, thus obtaining the non-return to estrus rates after 90 d (NRR). Results showed an increased rate of double-stranded breaks in the first period (0-2 h: 1.29 ± 1.01%/h vs. 2-4 h: 0.13 ± 1.37%/h; P < 0.01), whereas the rate of sperm with moderate + high single-stranded breaks was higher in the second period (0-2 h: 3.52 ± 7.77 %/h vs. 2-4h: 21.06 ± 11.69 %/h; P < 0.0001). Regarding sperm physiology, viability decrease rate was different between the two periods (0-2 h: − 4.49 ± 1.79%/h vs. 2-4 h: − 2.50 ± 3.39%/h; P = 0.032), but the progressive motility decrease rate was constant throughout post-thawing incubation (0-2 h: − 4.70 ± 3.42%/h vs. 2-4 h: − 1.89 ± 2.97%/h; P > 0.05). Finally, whereas no correlations between bull fertility and any dynamic parameter were found, there were correlations between the NRR and the basal percentage of highly-damaged sperm assessed with the alkaline Comet ( Rs = − 0.563, P = 0.003), between NRR and basal progressive motility ( Rs = 0.511, P = 0.009), and between NRR and sperm with high ROS at 4 h post-thaw ( Rs = 0.564, P = 0.003). Conclusion The statistically significant correlations found between intracellular ROS, sperm viability, sperm motility, DNA damage and chromatin deprotamination suggested a sequence of events all driven by oxidative stress, where viability and motility would be affected first and sperm chromatin would be altered at a later stage, thus suggesting that bovine sperm should be used for fertilization within 2 h post-thaw. Fertility correlations supported that the assessment of global DNA damage through the Comet assay may help predict bull fertility.