Expression of lactate dehydrogenase isozyme X in haploid cells of pigeon testis

Electrophoretic patterns of lactate dehydrogenase (EC 1.1.1.27) from adult testes show the existence of three different phenotypes for the isozyme X or C4 in populations of racing homer pigeons. These phenotypes are the expression of two different alleles at the Ldh c locus. Analysis of electrophoretic patterns of lactate dehydrogenase from lysates of mature spermatozoa isolated from pigeons heterozygous at the Ldh c locus indicates that the two different alleles are expressed in haploid cells. It is concluded that transcription of the gene coding for isozyme X must occur only in pre-meiotic cells.