Tyrosinase activation in eggs ofRana pipiens

✍ Scribed by Turney, Tully H.

• Book ID: 102335999
• Publisher: John Wiley and Sons
• Year: 1964
• Tongue: English
• Weight: 485 KB
• Volume: 157
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1401570310

✦ Synopsis

In reporting investigations of tyrosinase activity during early development of R a m pipiens embryos, Stearns and Goldstein ('56) reported that tyrosinase activity could be measured in fertilized eggs of Rana pipiens. These observations were extended in this laboratory to include parthenogenetically activated eggs. It was noted, however, that unfertilizable ovarian eggs did not display tyrosinase activity when exposed to parthenogenetic stimuli and, furthermore, unfertilizable ovarian eggs did not display tyrosinase activity when exposed to certain chemical reagents, such as chloroform vapor, that were effective in initiating tyrosinase activity in fertilizable eggs.

These observations implied the existence of a possible relationship between tyrosinase activity and egg activation and suggested that a detailed examination of tyrosinase activation in this material might provide valuable clues to the biochemistry of embryonic egg activation. However, through the use of reagents that react with copper enzymes, (lO-*M 8- quinolinol (8-hydroxyquinoline), and M 2,9-dimethyl-1 ,lo-phenanthroline (neocuproine)) it was possible to embryologically activate the egg without a concomitant activation of tyrosinase. Conversely, by varying exposure times to ultraviolet light, it was possible to produce egg preparations that were embryologically unactivated with respect to visual criteria, such as rotation and cleavage furrow formation, but which displayed an active tyrosinase metabolism.

These observations suggest that the phenomenon of tyrosinase activation, although accompanying egg activation, is not contingent on the successful achievement of the latter process. Consequently attention was given to the mechanics of tyrosinase activation in eggs of Rana