Ultrastructural Localization of Hair Keratin Homologs in the Claw of the Lizard Anolis Carolinensis

The study investigated the presence and localization of hair keratin homologs in the claws of the lizard Anolis carolinensis. Researchers found that two hair keratin homologs, hard acid keratin 1 (HA1) and hard basic keratin 1 (HB1), were expressed in the upper and precorneous layers of the lizard's claws, but not in the basal and lower spinosus layers. Using immunogold labeling and electron microscopy, the study revealed that these keratins were organized in long, parallel bundles in the precorneous layers, similar to the structure of mammalian hair. The findings suggested a potential interaction between alpha-keratins and beta-keratins during claw morphogenesis, providing insights into the similarities between lizard claws and mammalian hard epidermal appendages.