Patterns and metamorphic changes of serum proteins in amphibia.

1. Serum proteins in the metamorphosing larvae and adult animals ofRana temporaria, Bombina variegata, Bufo bufo andTriturus alpestris were separated by polyacrylamide gel electrophoresis. Based on various specific staining reactions the occurrence of albumin, transferrin, glycoprotein, lipoprotein and possibly haptoglobin was identified. 2. In general, the electrophoretic patterns become increasingly more complex with the progress of metamorphosis. Detailed analyses revealed the appearance of various new serum proteins both at the time of metamorphosis and during adult maturation. 3. In all three anuran species there is a rapid increase in the total serum protein concentration as metamorphosis proceeds. The albumin fraction shows the highest increasing rate, resulting in a two- to fivefold increase of the albumin/globulin ratio with the completion of metamorphosis. During postmetamorphic growth this ratio remains constant in spite of the continuous rise of the total concentration. Similar changes of the serum protein pattern have been observed in premetamorphic larvae ofR. temporaria andB. bufo treated with thyroxine. 4. T. alpestris differs from the three anurans in having a much smaller increase of the total serum protein concentration and showing no change of the albumin/globulin ratio at metamorphosis. Instead, a maximum increase of protein in the gel section of relatively slow anodal-moving globulins was observed. 5. The metabolic and molecular aspects of the changes of serum proteins during amphibian metamorphosis are discussed.