Semester of Graduation

Spring

Degree

Master of Science (MS)

Department

Animal Sciences

Document Type

Thesis

Abstract

Oocyte vitrification, while beneficial for research and species conservation, has limited success due to cryoinjury to the meiotic spindle. This study aimed to evaluate treatments to improve meiotic spindle recovery after vitrification by treating bovine oocytes with either a microtubule stabilizing agent, or a microtubule recovery agent. In the first two experiments, Taxol and epothilone B were used to treat bovine oocytes before vitrification. Both compounds have microtubule stabilizing properties and are known antimitotic compounds commonly used in cancer treatment. Oocytes were incubated with one of the microtubule stabilizing agents for 15 minutes before vitrification at one of three concentrations each. Taxol treatment at 2.0 µM significantly increased the proportion of oocytes with normal microtubule distribution and chromosome arrangement after warming. Treatment with 1.0 µM had no effect and 0.5 µM had a negative effect on meiotic spindle recovery. Epothilone B treatment at all concentrations significantly increased the proportion of oocytes with meiotic spindle disruption and abnormally dispersed chromosomes.

In the second set of experiments, Rho-associated coiled-coil kinase (ROCK) inhibition and glutathione (GSH) accumulation were investigated as recovery treatments after vitrification. Oocytes were incubated with either Y-27632 or combinations of cysteine and cysteamine for four hours after warming. Treatment with 5 µM and 10 µM of Y-27632 to inhibit ROCK activity significantly increased the proportion of vitrified oocytes with normal microtubule distribution and chromosome arrangement. When oocytes were incubated with 20 µM of Y-27632 there was no effect on spindle recovery. Incubation with 100 µM of cysteamine also had no effect on spindle recovery while 0.6 mM of cysteine and both 0.6 mM of cysteine and 100 µM of cysteamine significantly increased oocytes with normal microtubule distribution and chromosome arrangement.

Committee Chair

Bondioli, Kenneth R.

Available for download on Thursday, March 07, 2024

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