SOME EVOLUTIONARY PATTERNS IN FISHES' BLOOD

¹ Gulf Coast Research Laboratory, Ocean Springs, Mississippi, and Department of Biochemistry, University of Mississippi School of Medicine, Jackson, Miss.

1. A study was made, by electrophoretic techniques, of the plasma proteins of 26 species of elasmobranch and teleostome fishes from the northern Gulf of Mexico.

2. A general increase was found in the amount of plasma proteins from lower to more specialized fishes. Elasmobranchs lacked albumin in the plasma. This condition of analbuminemia also held true for all the gars and half of the Clupeidae studied; it generally disappeared in the more specialized fishes, but not entirely, and was found in two species of the Perciformes. There was a gradual increase in the number of globulin fractions of the plasma, from lower to higher fishes, among the Orders of fishes, which did not always hold true at species levels.

3. Closely related species could be distinguished by the presence or absence and varying amounts of plasma proteins, but there were exceptions and certain species in the same family could only be differentiated doubtfully on that basis.

4. The plasma proteins of the fishes examined showed a trend of increasing complexity from the generalized to the more specialized fishes.

5. The content of the chief electrolytes, Na, K and Cl, in the plasma of marine sharks was found to be much higher than in teleosts, in confirmation of earlier workers.

6. Total cholesterol in the plasma of sharks and gars was found in the same range as in mammals, but in the remaining teleost fishes it was a great deal higher.

7. Relations between cholesterol and plasma proteins in the blood of fishes resemble pathological conditions in mammals, including man.