V. V. Luu

Astaxanthin present in the maturation medium reduces negative effects of heat shock on the developmental competence of porcine oocytes

Astaxanthin, one of the most common carotenoids, elicits antioxidant effects on cellular viability and embryonic development. This study was conducted to investigate the effects of astaxanthin on maturation, fertilization and development of porcine oocytes matured in vitro under heat stress conditions, and then fertilized and cultured under standard conditions. Porcine oocytes were cultured in maturation medium supplemented with different concentrations of astaxanthin (0, 0.25, 0.5 or 1 ppm) for 46 h at either 38.5 or 41 °C. In comparison to oocytes cultured at 38.5 °C, the exposure of porcine oocytes to 41.0 °C during in vitro maturation (IVM) significantly inhibited maturation and development of fertilized oocytes to the blastocyst stage. Supplementation of maturation medium with astaxanthin (0.5 ppm) significantly improved oocyte maturation, fertilization and development to the blastocysts stage in both oocyte groups. However, the total cell number and apoptosis index of blastocysts did not differ among groups. Moreover, astaxanthin (0.5 ppm) significantly increased the rate of oocytes that reached metaphase II and decreased proportion of apoptotic oocytes exposed to H2O2 (1.0mM) during IVM. In summary, we demonstrated that supplementation of maturation medium with astaxanthin (0.5 ppm) exerted antioxidative effects and improved the ability of maturation, fertilization, and development of porcine oocytes exposed to heat stress.

Effects of green tea polyphenol on the quality of canine semen after long-term storage at 5°C.

The aim of the present study was to determine the effects of green tea polyphenol on the quality of canine semen after long-term storage at 5°C. The supplementation of a Tris-egg yolk extender with polyphenol (0.5, 0.75, or 1mg/mL) increased the motility and viability of sperm preserved for four weeks at 5°C.

Effect of Sericin Supplementation During In Vitro Maturation on the Maturation, Fertilization and Development of Porcine Oocytes

This study aimed to examine the effects of sericin supplementation during in vitro oocyte maturation on the nuclear maturation, fertilization and development of porcine oocytes. Cumulus-oocyte complexes (COCs) were cultured in maturation medium supplemented with 0 (control), 0.1, 0.5, 1.0, 2.5 or 5.0% sericin and were then subjected to in vitro fertilization and embryo culture. More COCs matured with 1.0% sericin underwent germinal vesicle breakdown and reached metaphase II compared with the control COCs matured without sericin (p < 0.01). The proportions of oocytes with DNA-fragmented nuclei did not differ between the groups, regardless of the sericin level. The total fertilization rate of oocytes matured with 1.0% sericin was higher (p < 0.05) than that of oocytes matured with 0.1%, 2.5% and 5.0% sericin. Supplementation with more than 1.0% sericin decreased the DNA fragmentation index of the blastocysts compared with the control group (p < 0.05). However, the supplementation of the maturation medium with sericin had no beneficial effects on the cleavage, development to the blastocyst stage and the total cell number of the embryos. Our findings indicate that supplementation with 1.0% sericin during maturation culture may improve the nuclear maturation and the quality of the embryos but does not affect blastocyst formation.

Motility and fertility of boar semen after liquid preservation at 5°C for more than 2 weeks.

This study investigated the effects of skim milk on the quality and fertility of boar spermatozoa under long-term chilled preservation. Semen samples were stored in Modena solution supplemented with 0 (control) to 50 mg/mL skim milk at 5°C for 4 weeks; spermatozoa stored with 7.5 and 15 mg/mL of skim milk (7.5-SM and 15-SM groups, respectively) exhibited significantly higher motility indices than those of the control group up to 3 weeks (P < 0.05), and the 7.5-SM group showed improved motility indices even after 4 weeks (P < 0.05). In vitro fertilization using spermatozoa in the 7.5-SM and 15-SM groups stored at 5°C for 2 weeks showed significantly higher fertilization rates of spermatozoa and the development rates to blastocyst than the control group (P < 0.05), and the 7.5-SM group showed similar rates of fertilization and blastocyst formation in the fresh non-stored spermatozoa group. After artificial insemination using spermatozoa stored for 2 weeks in the 7.5-SM group, healthy piglets were obtained. Boar spermatozoa can be stored at 5°C in a Modena solution containing skim milk. Supplementation of 7.5 mg/mL skim milk improves boar spermatozoa motility and fertility even after liquid preservation at 5°C for 2 weeks.

Comparison of activation ability between feline and bovine oocytes.

Research comparing the activation sensitivity of oocytes to chemical treatment among mammalian species remains limited. We compared the activation ability of oocytes from bovine and feline ovaries when treated with ethanol alone, with ethanol and cycloheximide, and without any chemical treatment; the oocytes were then cultured for 72 h. After in vitro maturation (IVM), 5% of feline oocytes were activated and 1% were cleaved, whereas there were no prematurely activated bovine oocytes. Activation rates with ethanol and ethanol/cycloheximide were significantly higher (P < 0.01) in bovine oocytes than in feline oocytes (74.2% vs. 34.1% and 86.3% vs. 52.5%, respectively). Thus, our findings indicate that feline oocytes can be prematurely activated by the end of IVM, and that bovine oocytes may have a higher sensitivity of parthenogenetic activation to chemical treatment than do feline oocytes.