Genetic and embryological studies of albinism in Rana pipiens

Albinism in the leopard frog is due to a recessive gene ( alb ) in the homozygous condition. Heterozygous females produce normal, pigmented eggs. After fertilization of these eggs by sperm from another heterozygote, all progeny remain normally pigmented until after hatching when the albino progeny can be detected. Since melanin deposition in oocytes occurs prior to segregation of the alb and + alleles, the wild‐type gene may be transcribed and translated in the oocytes. Alternatively, the product of the + allele may be synthesized exogenously and incorporated into the oocytes during oogenesis. The results of embryonic transplant experiments suggest that the albino gene is expressed within the neural crest derivatives. Albino hosts support differentiation of wild‐type melanophores. Albino dorsal mesoderm induces melanophore differentiation in wild‐type neural crest derivatives. Albinos were less viable than their wild‐type siblings in the laboratory environment. Albino larvae developed scoliosis with high frequency, and albino frogs had a higher mortality rate after metamorphosis than their wild‐type siblings.