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Summary. This study examines the effects of pig follicular fluid on the maturation of pig oocytes and on their subsequent fertilizing and developmental capacity in vitro. The addition of pig follicular fluid or its fractions obtained by ultrafiltration, gel filtration and ion-exchange chromatography to maturation medium significantly increased the rates of nuclear maturation, normal fertilization and normal cleavage of pig oocytes after fertilization in vitro: the rates of normal fertilization and cleavage were 2\p=n-\4times higher than those in the control medium. The efficacy of pig follicular fluid was lost after heating at 56\s=deg\Cfor 30 min, whereas no significant decrease in activity was observed after defatting. In addition, the effective component(s) was partially purified by ultrafiltration, gel filtration and ion-exchange chromatography: the activity was observed in the fraction (UF2; Mr 10 000\p=n-\20000) obtained by ultrafiltration. Activity was found in the first fraction (G1) obtained by gel filtration of UF2. Among three fractions obtained by ion-exchange chromatography of Gl, only the third fraction had the activity. The results indicate that pig follicular fluid contains an acidic substance(s) (Mr 10 000\p=n-\200 000) that promotes oocyte maturation.

The nucleotide sequence of the uricase gene from the thermophilic bacterium Bacillus sp. TB-90 was determined. The primary structure of the uricase deduced from the nucleotide sequence comprised 332 amino acids, with a total molecular mass of 37,994 Da. The molecular mass of the subunit of the uricase produced by the transformant of Escherichia coli agreed well with this value. However, the molecular mass of a subunit of the uricase produced by Bacillus sp. TB-90 was found to be 34,000 Da by SDS-PAGE. The difference between these molecular masses was attributed to processing of the C-terminal 13 amino acid residue in Bacillus sp. TB-90. Comparison of the enzymatic properties of both uricases showed that the thermostability of the uricase produced by the transformant was enhanced by about 10 degrees C in comparison to that produced by Bacillus sp. TB-90.

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