Zoological Studies

Vol. 50 No. 4, 2011

The Process of Cornification in the Horny Teeth of the Lamprey Involves Proteins in the Keratin Range and Other Keratin-Associated Proteins

Lorenzo Alibardi1,* and Anna Segalla2

1Dipartimento di Biologia evoluzionistica sperimentale, Univ. of Bologna, Bologna 40126, Italy
2Dipartimento di Biologia, Univ. of Padova, Padova, 35100, Italy

Lorenzo Alibardi and Anna Segalla (2011) A microscopic and electrophoretic study was conducted on the horny teeth of the lamprey to increase our knowledge of the process of cornification. Electron-dense bundles of keratin but no keratohyaline-like granules accumulated in the cytoplasm of transitional cells that were incorporated in the dense stratum corneum of the tooth. Mature corneocytes were delimited by a cell corneous envelope and formed corneous microridges on the tooth surface. Although the increase in the electron density of the corneous layer suggested the presence of sulfur, the low to absent reaction for sulfhydryl groups indicated that cysteine was largely oxidized to form disulphide bonds in the corneous material of the teeth. A 2-dimensional electrophoretic analysis of the corneous material from the horny teeth showed the presence of acidic proteins, most likely keratins of 45-66 kDa. Keratin 10 immunoreactivity was present in the teeth. Based on the size, it is likely that acidic and basic non-keratin proteins of 16-20 kDa were also present in the oral mucosa, generally in higher amounts than keratins. This suggests that the low-molecular-weight basic proteins are likely associated with acidic keratins to produce the dense corneous material of the tooth, a process that also occurs in hard skin derivatives of other vertebrates.

Key words: Lamprey, Horny teeth, Cornification, Keratins, Keratin-associated proteins.

*Correspondence: Tel: 39-051-2094257. Fax: 39-051-2094286. E-mail:lorenzo.alibardi@unibo.it