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Ultrastructural immunolocalization of alpha-keratins and associated beta-proteins (beta-keratins) suggests a new interpretation on the process of hard and soft cornification in turtle epidermis.

Abstract

The epidermis of soft-shelled and hard-shelled turtles has been compared to determine the origin of the different cornification. Immunolocalization of acidic alpha-keratin (AK2) of 45-50 kDa in tonofilaments of the epidermis in Apalone spinifera and absence in the corneous layer where desquamating corneocytes are present supports the biochemical data. Corneocytes shows a weak to absent immunolabeling for beta-proteins (formerly beta-keratins) of 14-16 kDa while sparse immunolabeled corneous granules are seen in the pre-corneous layer. In the hard-shelled turtle Pseudemys nelsonii differentiating corneocytes contain small level of acidic alpha-keratin while beta-proteins of 10-17 kDa form dense aggregates of corneous material among tonofilaments. Corneocytes do not desquamate but remain tightly connected determining an increase in thickness of the corneous layer that becomes mechanically stiff and resistant. Since both species possess beta-proteins in shelled and non-shelled areas of the epidermis the difference in hardness of the corneous layer is not due to the alternation between beta-keratin versus alpha-keratin. Mechanical resilience of the corneous layer derives from the accumulation of alpha-keratins, beta- and likely of other proteins in corneocytes of the shell in hard-shelled turtles. In the softer epidermis of hard-shelled turtles and in the soft-shelled turtle a more rapid and continuous turnover of corneocytes is present and no accumulation of beta-proteins and corneocytes takes place. It is hypothesized that the dermis derived from the carapacial ridge during development remains localized underneath the shell epidermis in hard-shelled turtles and influences the formation of the hard corneous epidermis.

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  • Publisher Full Text
  • Authors+Show Affiliations

    Comparative Histolab and Department of Biology, University of Bologna, Italy. Electronic address: lorenzo.alibardi@unibo.it.

    Source

    MeSH

    Animal Shells
    Animals
    Blotting, Western
    Epidermis
    Immunohistochemistry
    Keratins
    Microscopy, Electron, Transmission
    Microscopy, Immunoelectron
    Molecular Weight
    Turtles
    beta-Keratins

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    23958576

    Citation

    Alibardi, L. "Ultrastructural Immunolocalization of Alpha-keratins and Associated Beta-proteins (beta-keratins) Suggests a New Interpretation On the Process of Hard and Soft Cornification in Turtle Epidermis." Micron (Oxford, England : 1993), vol. 52-53, 2013, pp. 8-15.
    Alibardi L. Ultrastructural immunolocalization of alpha-keratins and associated beta-proteins (beta-keratins) suggests a new interpretation on the process of hard and soft cornification in turtle epidermis. Micron. 2013;52-53:8-15.
    Alibardi, L. (2013). Ultrastructural immunolocalization of alpha-keratins and associated beta-proteins (beta-keratins) suggests a new interpretation on the process of hard and soft cornification in turtle epidermis. Micron (Oxford, England : 1993), 52-53, pp. 8-15. doi:10.1016/j.micron.2013.07.002.
    Alibardi L. Ultrastructural Immunolocalization of Alpha-keratins and Associated Beta-proteins (beta-keratins) Suggests a New Interpretation On the Process of Hard and Soft Cornification in Turtle Epidermis. Micron. 2013;52-53:8-15. PubMed PMID: 23958576.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Ultrastructural immunolocalization of alpha-keratins and associated beta-proteins (beta-keratins) suggests a new interpretation on the process of hard and soft cornification in turtle epidermis. A1 - Alibardi,L, Y1 - 2013/07/24/ PY - 2012/12/29/received PY - 2013/07/03/revised PY - 2013/07/06/accepted PY - 2013/8/21/entrez PY - 2013/8/21/pubmed PY - 2014/4/24/medline KW - Alpha-keratins KW - Beta-proteins KW - Immunoblotting KW - Immunogold KW - Turtle epidermis SP - 8 EP - 15 JF - Micron (Oxford, England : 1993) JO - Micron VL - 52-53 N2 - The epidermis of soft-shelled and hard-shelled turtles has been compared to determine the origin of the different cornification. Immunolocalization of acidic alpha-keratin (AK2) of 45-50 kDa in tonofilaments of the epidermis in Apalone spinifera and absence in the corneous layer where desquamating corneocytes are present supports the biochemical data. Corneocytes shows a weak to absent immunolabeling for beta-proteins (formerly beta-keratins) of 14-16 kDa while sparse immunolabeled corneous granules are seen in the pre-corneous layer. In the hard-shelled turtle Pseudemys nelsonii differentiating corneocytes contain small level of acidic alpha-keratin while beta-proteins of 10-17 kDa form dense aggregates of corneous material among tonofilaments. Corneocytes do not desquamate but remain tightly connected determining an increase in thickness of the corneous layer that becomes mechanically stiff and resistant. Since both species possess beta-proteins in shelled and non-shelled areas of the epidermis the difference in hardness of the corneous layer is not due to the alternation between beta-keratin versus alpha-keratin. Mechanical resilience of the corneous layer derives from the accumulation of alpha-keratins, beta- and likely of other proteins in corneocytes of the shell in hard-shelled turtles. In the softer epidermis of hard-shelled turtles and in the soft-shelled turtle a more rapid and continuous turnover of corneocytes is present and no accumulation of beta-proteins and corneocytes takes place. It is hypothesized that the dermis derived from the carapacial ridge during development remains localized underneath the shell epidermis in hard-shelled turtles and influences the formation of the hard corneous epidermis. SN - 1878-4291 UR - https://www.unboundmedicine.com/medline/citation/23958576/Ultrastructural_immunolocalization_of_alpha-keratins_and_associated_beta-proteins_(beta-keratins)_suggests_a_new_interpretation_on_the_process_of_hard_and_soft_cornification_in_turtle_epidermis L2 - https://linkinghub.elsevier.com/retrieve/pii/S0968-4328(13)00104-2 DB - PRIME DP - Unbound Medicine ER -