work with Donald Shaw on the absorption of 

 anti-SKipjack serum with the cells of individual 

 white croakers revealed minor differences in 

 the absorptive power of the cells of individual 

 fish. These differences were accentuated when 

 cells of the walleye surfperch ( Hyperpro sopon 

 argenteum Gibbons) were included as test anti- 

 gen. The relationships among the antigens 

 involved are complex, from which it is appar- 

 ent that interspecific combinations of different 

 species of fish with respect to immunization, 

 absorption, and testing may be profitably manip- 

 ulated in the study of erythrocyte antigens . 

 Table 12 shows that the absorption of anti-skip- 

 jack serum varies with the cells of individual 

 fish. This variation is revealed by comparing 

 the residual agglutination titers for the cells of 

 a single walleye surfperch. Two "types" of 

 white croaker are indicated on the basis of the 

 amount of agglutinin remaining. 



The compexity of this relationship is 

 further shown by the fact that the two anti- 

 albacore serums (Nos. 10 and 14) failed to ag- 

 glutinate either white croaker or shiner sea- 

 perch cells, while agglutinating the cells of 

 skipjack and other tuna to varying degrees 

 (review table 7) . 



A final point is that the agglutination of 

 white croaker cells by anti- skipjack serum can 

 be inhibited through the use of previously frozen 

 whole skipjack blood, thawed and centrifuged 

 free of cellular debris. This observation shows 

 that it may be possible to utilize inhibition tech- 

 niques in investigations where only frozen whole 

 bloods can be obtained. 



DISCUSSION 



The observations and experiments re- 

 ported above show that it is very probable that 

 serological techniques can be applied profitably 

 to the study of racial and specific variation in 

 tunas. Not only do individual variations exist 

 among the erythrocyte antigens of single species 

 (oceanic skipjack) but species variations also 

 exist among the yellowfin, albacore, little tunny, 

 and skipjack. In addition, the bloods of tunas 

 seem to be easy to collect and to work with . 

 Further, it is apparent that not only can specific 



immune serums be prepared against tuna blood, 

 but that systematic research may develop the 

 usefulness of "normal" antibodies as reagents 

 for distinguishing individual variations as has 

 been done, for example, with eel serum in hu- 

 man blood-group studies (Race and Sanger, 1954) 

 and with bovine serum in chicken blood-group 

 studies (Briles, Briles, and Irwin, 1951). 



The widespread occurrence of hetero- 

 genetic antigens among fish also offers various 

 opportunities for further investigation of sero- 

 logical variations within tunas, as is shown 

 through examples of the use of inhibition and ab- 

 sorption techniques. A review of the various 

 data presented in this paper suggests consider- 

 able complexity among the specific relations dt 

 the heterogenetic antigens so far detected, and 

 that any detailed study of a single group should 

 reveal information of general interest concern- 

 ing the evolution of these antigens among fish in 

 general . 



LITERATURE CITED 



Briles, W.E., R.W. Briles, andM.R. Irwin. 



1951 Differences in specificity of the 

 antigenic products of a series of alleles 

 in the chicken. Genetics 37:359-368. 



Chaplin, H., and P.L . MoUison. 



1953 Improved storage of red cells at 

 -20°C. Lancet 1:215-219. 



Gushing, J.E. 



1952a Serological differentiation of fish 

 bloods. SCIENCE 115:404-405. 



1952b Individual variation in the hemag- 

 glutinin content of yellowfin tuna and 

 skipjack bloods . Jour. Immunol. 

 68:543-547. 



Gushing, J.E., andL. Sprague . 



1952 The agglutination of fish erythro- 

 cytes by normal human sera. Biol. Bull. 

 103:328-335. 



1953 Agglutinations of the erythrocytes of 

 various fishes by human and other sera. 

 Amer. Nat. 87:307-315. 



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