12. IMMUNOLOGY OF FISH
487
those of the ABO system, also occur among diverse forms of invertebrates
and microorganisms (cf. Cushing et al., 1963). Of course, many species
have yet to be studied, including the cyclostomes and the fish lacking
erythrocyte nuclei, but it is a reasonable prediction that the occurrence
of polymorphic blood group antigens (if not on erythrocytes, then on
tissues or in solution) is ubiquitous, at least as far as the vertebrates
are concerned. The study of blood groups relates to immunology in a
variety of ways, the most fundamental of which is that the variations
involved are antigenic polymorphism that are detected through the use
of specific antibodies. These variations are determined in a simple
and direct manner by a number of different genetic loci exhibiting
multiple allelism. So many combinations of specificities are known
in extensively studied species such as humans and cattle that it is possible to demonstrate that each individual potentially has an overall blood
type individuality all his own. Additionally, evolution has produced
differences among the frequencies of gene controlling antigens in different populations. Comparison of these can, under suitable circumstances,
provide information useful as an aid in evaluating the extent to which
a species is divided into subpopulations (demes, races). As noted in the
Introduction, the subject of the blood groups of marine animals has
been reviewed with particular attention to the problem of subpopulation identification (Cushing, 1964), and W. de Ligny ( 1969) includes
additional information, together with a very comprehensive consideration of other molecular polymorphisms in fish. In addition to references cited in Cushing (1964), the reader’s attention is called to two
texts useful in providing background material. The first of these is
Hildemann’s “Immunogenetics” ( 1970), and the second, the fifth edition
of Race and Sanger’s “Blood Groups in Man” (1968).
The most exciting blood group studies on fish currently underway
are those of Fujino (1967) and Fujino and Kazama (1968) on the Pacific
skipjack, Katsuwonis pelamis. Blood group antibodies and antigenic polymorphism in tuna were first reported by Cushing (1952, 1956). Sprague
and his associates, working at the U.S. Bureau of Commercial Fisheries
Biological Laboratory, Honolulu, subsequently did extensive work to
establish reagents revealing a large series of blood groups in skipjack
and to show that these provided evidence of at least three reproductively
isolated populations distributed over a wide expanse of the Central
Pacific (Sprague and Holloway, 1962), as well as the possibility that two
different subpopulations associated with changes in water masses occur
around Hawaii (Sprague, 1964). A new blood group system termed
Y, as distinct from the B system of Sprague and Holloway, has been
discovered by Fujino and Kazama in skipjack in Hawaiian waters. This
487
those of the ABO system, also occur among diverse forms of invertebrates
and microorganisms (cf. Cushing et al., 1963). Of course, many species
have yet to be studied, including the cyclostomes and the fish lacking
erythrocyte nuclei, but it is a reasonable prediction that the occurrence
of polymorphic blood group antigens (if not on erythrocytes, then on
tissues or in solution) is ubiquitous, at least as far as the vertebrates
are concerned. The study of blood groups relates to immunology in a
variety of ways, the most fundamental of which is that the variations
involved are antigenic polymorphism that are detected through the use
of specific antibodies. These variations are determined in a simple
and direct manner by a number of different genetic loci exhibiting
multiple allelism. So many combinations of specificities are known
in extensively studied species such as humans and cattle that it is possible to demonstrate that each individual potentially has an overall blood
type individuality all his own. Additionally, evolution has produced
differences among the frequencies of gene controlling antigens in different populations. Comparison of these can, under suitable circumstances,
provide information useful as an aid in evaluating the extent to which
a species is divided into subpopulations (demes, races). As noted in the
Introduction, the subject of the blood groups of marine animals has
been reviewed with particular attention to the problem of subpopulation identification (Cushing, 1964), and W. de Ligny ( 1969) includes
additional information, together with a very comprehensive consideration of other molecular polymorphisms in fish. In addition to references cited in Cushing (1964), the reader’s attention is called to two
texts useful in providing background material. The first of these is
Hildemann’s “Immunogenetics” ( 1970), and the second, the fifth edition
of Race and Sanger’s “Blood Groups in Man” (1968).
The most exciting blood group studies on fish currently underway
are those of Fujino (1967) and Fujino and Kazama (1968) on the Pacific
skipjack, Katsuwonis pelamis. Blood group antibodies and antigenic polymorphism in tuna were first reported by Cushing (1952, 1956). Sprague
and his associates, working at the U.S. Bureau of Commercial Fisheries
Biological Laboratory, Honolulu, subsequently did extensive work to
establish reagents revealing a large series of blood groups in skipjack
and to show that these provided evidence of at least three reproductively
isolated populations distributed over a wide expanse of the Central
Pacific (Sprague and Holloway, 1962), as well as the possibility that two
different subpopulations associated with changes in water masses occur
around Hawaii (Sprague, 1964). A new blood group system termed
Y, as distinct from the B system of Sprague and Holloway, has been
discovered by Fujino and Kazama in skipjack in Hawaiian waters. This