Aspects of gene regulation in the diploid and tetraploid Odontophrynus americanus (Amphibia, Anura, Leptodactylidae)

Abstract Erythropoietic and hemoglobin DNA transcriptional activities were analyzed in the diploid and the tetraploid Odontophrynus americanus.Flow cytometric analyses of DNA, RNA and mitochondrial contents showed increased genic activity in both diploid and tetraploidanimals during erythropoiesis in vivo elicited by pretreatment phenylhydrazine. Generally, higher values were seen in immature tetraploiderythroid cells. On the 10th day of recovery from anemia, large amounts of messenger RNA were found in both specimens. Based on themitochondrial content, the tetraploid cells had more intense energy metabolism than the diploid cells. Diploid O. americanus had aboutthree times more erythroid cells than tetraploid specimens, indicating that there were differences in the regulatory mechanisms of erythroidcells. Hematological parameters showed that tetraploid cells had 30% more hemoglobin than the diploid, suggesting a regulatory mechan-ism of hemoglobin synthesis at the transcriptional level. Cytoplasmic inclusions resembling Heinz bodies were found in both typ es of cells.In the tetraploid cells they were previously found associated with RNA or RNP, suggesting that other regulatory system which co ntrolsthe accumulation of nontranslated RNA transcribed in excess must be present. These differences at the physiological and molecul ar levelsduring erythropoiesis reinforce the hypothesis that speciation is occurring between diploid and tetraploid O. americanus .