Expression and characterization of Xenopus type I collagen alpha 1 (COL1A1) during embryonic development

A cDNA encoding Xenopus type I collagen alpha 1 (Xenopus COL1A1) has been i solated from an ovary cDNA library. The COL1A1 cDNA is approximately 5.7 kb pairs and encodes 1447 amino acids. The putative COL1A1 polypeptide shares high identities of amino acid sequence with other vertebrate COL1A1 protei ns. The level of Xenopus COL1A1 transcripts was increased markedly in the p osterior region of the embryo at the tail-bud stage, then gradually spread to the anterior region. Histological observations of the tail-bud embryos s howed that COL1A1 was mainly expressed in the inner layer of the posterior dorsal epidermis exposed to the somite mesoderm, except for in the dorsal f in. Less intense signals were also detected in the outer layer of the dorsa l epidermis and dermatome. The expression of COL1A1 was increased in poster iorized embryos resulting from treatment with retinoic acid but decreased i n hyper-dorsalized embryos resulting from lithium chloride treatment. These results suggest that COL1A1 is a major component of the dorsal dermis expo sed to the somite in Xenopus embryos, but its expression is not related to the temporal sequence of somite segregation.