Histocompatibility analyses in tetraploids induced from clonal triploid crucian carp and in gynogenetic diploid goldfish

Abstract

Histocompatibility analyses in goldfish were performed using the tetraploid goldfish‐crucian carp hybrid and the first generation of gynogenetic diploid (GD1) goldfish. Tetraploids were obtained by crossing clonal triploid crucian carp with goldfish. GD1 goldfish were produced by the suppression of the second meiotic division. Tetraploid scale grafts on triploid clone members evoked an acute rejection in 4–6 days, whereas the reverse transplants were accepted or rejected chronically. Reciprocal grafting between tetraploids showed subacute rejection in 10–12 days, although some fish showed chronic rejection in 20–30 days. On the other hand, scale grafts reciprocally exchanged among triploids were intact even 3 months after grafting, although some of them showed a unidirectional rejection pattern. Furthermore, allograft rejection among gynogens occurred between 5 and 20 days, whereas all the scale allografts between members of control siblings were rejected within 9 days. In addition, neither accelerated acute rejection nor acceptance of allografts was observed in grafts exchanged among GD1 goldfish. These results suggest that single doses of histocompatibility alleles are effective in eliciting acute rejection, and each of the fourth haploid set of chromosomes originating from paternal goldfish might share the same histocompatibility antigens to a large extent. This experiment also indicates that the genecentromere recombination rate is quite high with respect to the histocompatibility loci in this species.