Figure 1.

Detection of phenoloxidase activity in mature eggs. Dissection of eggs, brief exposure of the eggs in ethanol, incubation of the eggs in phosphate buffer, and subsequent HPLC-ED analysis of supernatant of egg mixture were carried out as described in the Experimental Procedures. (A) Chromatogram showing the detection of tyrosine, dopa and dopamine in phosphate buffer at 15 min after incubation of ethanol-exposed mature eggs. (B) Chromatogram illustrating the relative amount of tyrosine and other electrochemically active compounds in supernatant of a briefly sonicated egg mixture following 15 min incubation. Separation of tyrosine, dopa and dopamine was achieved by reverse phase separation using a reverse phase column (250 × 4.6 mm, Varian, Inc.) with a mobile phase consisting of 0.1 m phosphate buffer (pH 3.0) containing 4% acetonitrile at a flow rate of 0.6 ml per min. The retention times for dopa, dopamine and tyrosine at the applied separation conditions were 7.5, 8.3 and 9.5 min, respectively.