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Special Issue "Neurobiology of Protein Synuclein"
Full text linkSynucleins are a family of proteins consisting of α, β, and γ synuclein (syn) [...]
Evolution of scales and their hard proteins in reptiles in relation to cornification of skin appendages in the amniote integument
No full textThe integument of lungfish: General structure and keratin composition
No full textThe aquatic environment poses less restrictions on mechanical and barrier performances in the integument of both marine and freshwater vertebrates, mainly fish and some amphibians, in comparison to the skin of terrestrial vertebrates (Whitear 1977; Zaccone et al. 2001; Alibardi 2006). As a result, apart from specific locations of the body in a few species of fishes and amphibians, the epidermis of aquatic vertebrates resembles the relatively poorly keratinised multi-layered epithelia found in the mucoses lining the respiratory or alimentary canals of terrestrial vertebrates (Whitear 1986a,b). In particular a corneal layer is missing over the general epidermis of fishes and perennibranchiate amphibians. Th is includes also sarcopterygian fish, both crossopterygians (Latimeria, saltwater) and dipnoans (freshwater). Th is chapter is mainly concerned with the skin, especially the epidermis of the Australian lungfish, Neoceratodus forsteri, which is compared where studies are available, with the epidermis of other species of dipnoans (Kitzan and Sweeny 1968; Imaki and Chavin 1975a,b, 1984). In addition to a previously published study (Alibardi and Joss 2003), N. forsteri skin derived from two extra larval stages are described and the keratins have been partially characterised
Fish Synucleins: An Update
Full text linkSynucleins (syns) are a family of proteins involved in several human neurodegenerative diseases and tumors. Since the first syn discovery in the brain of the electric ray Torpedo californica, members of the same family have been identified in all vertebrates and comparative studies have indicated that syn proteins are evolutionary conserved. No counterparts of syns were found in invertebrates suggesting that they are vertebrate-specific proteins. Molecular studies showed that the number of syn members varies among vertebrates. Three genes encode for α-, β- and γ-syn in mammals and birds. However, a variable number of syn genes and encoded proteins is expressed or predicted in fish depending on the species. Among biologically verified sequences, four syn genes were identified in fugu, encoding for α, β and two γ (γ1 and γ2) isoforms, whereas only three genes are expressed in zebrafish, which lacks α-syn gene. The list of "non verified" sequences is much longer and is often found in sequence databases. In this review we provide an overview of published papers and known syn sequences in agnathans and fish that are likely to impact future studies in this field. Indeed, fish models may play a key role in elucidating some of the molecular mechanisms involved in physiological and pathological functions of syn proteins
Characterization of keratins and associated proteins involved in the corneification of crocodilian epidermis
No full textCrocodilian keratinocytes accumulate keratin and form a corneous cell envelope of which the composition is poorly known. The present immunological study characterizes the molecular weight, isoelectric point (pI) and the protein pattern of alpha- and beta-keratins in the epidermis of crocodilians. Some acidic alpha-keratins of 47-68 kDa are present. Cross-reactive bands for loricrin (70, 66, 55 kDa), sciellin (66, 55-57 kDa), and filaggrin-AE2-positive keratins (67, 55 kDa) are detected while caveolin is absent. These proteins may participate in the formation of the cornified cell membranes, especially in hinge regions among scales. Beta-keratins of 17-20 kDa and of prevalent basic pI (7.0-8.4) are also present. Acidic beta-keratins of 10-16 kDa are scarce and may represent altered forms of the original basic proteins. Crocodilian beta-keratins are not recognized by a lizard beta-keratin antibody (A68B), and by a turtle beta-keratin antibody (A685). This result indicates that these antibodies recognize specific epitopes in different reptiles. Conversely, crocodilian beta-keratins cross-react with the Beta-universal antibody indicating they share a specific 20 amino acid epitope with avian beta-keratins. Although crocodilian beta-keratins are larger proteins than those present in birds our results indicate presence of shared epitopes between avian and crocodilian beta-keratins which give good indication for the future determination of the sequence of these proteins. (C) 2007 Elsevier Ltd. All rights reserved
Immunological characterization of a newly developed antibody for localization of a beta-keratin in turtle epidermis.
No full text[ARTICOLO
Immuno-cross reactivity of transglutaminase and cornification marker proteins in the epidermis of vertebrates suggests common processes of soft cornification across species
No full textIn differentiating mammalian keratinocytes proteins are linked to the plasma membrane by epidermal transglutaminases through N-ε-(γ- glutamyl)-lysine isopeptide bonds to form the cornified cell envelope. The presence of transglutaminases and their protein substrates in the epidermis of nonmammalian vertebrates is not known. The present study analyses the presence and localization of the above proteins in the epidermis using immuno-cross reactivity across different classes of amniotes. After immunoblotting, some protein bands appear labelled for loricrin, sciellin, and transglutaminase in most species. These proteins are scarce to absent in the epidermis of aquatic species (goldfish and newt) where a stratum corneum is absent or very thin. The molecular weight of transglutaminase immunoreactive bands generally varies between 40 to 62 kDa, with the most represented bands at 52-57 kDa in most species. The more intense loricrin- and sciellin-immunoreactive bands are seen at 50-55-62 kDa, but are weak or absent in aquatic vertebrates. Loricrine-like immunoreactivity is present in the epidermis where α-(soft)-keratinization occurs. Isopeptide bonds are mainly associated to bands in the range of 50-62 kDa. In vertebrates where hard-keratin is expressed (the beta-keratin corneous layer of sauropsids and in feathers) or in hair cortex of mammals, no loricrin-like, transglutaminase-, and isopeptide-bond-immunoreactivities are seen. Immunoblotting however shows loricrin-, sciellin-, and trasnsglutaminase-positive bands in the corneous layers containing β-keratin. Histologically, the epidermis of most amniotes shows variable transglutaminase immunoreactivity, but isopeptide-bond and sciellin immunoreactivities are weak or undetactable in most species. The limitations of immunohistochemical methods are discussed and compared with results from immunoblotting. In reptilian epidermis transglutaminase is mainly localized in 0.15-0.3 μm dense granules or diffuse in transitional α-keratogenic cells. In β-keratogenic cells few small dense granules show a weak immunolabeling. Transglutaminase is present in nuclei of terminal differentiating α- and β-keratinocytes, as in those of mature inner and outer root sheath. The present study suggests that keratinization based on loricrin, sciellin and transglutaminase was probably present in the stratum corneoum of basic amniotes in the Carboniferous. These proteins were mainly maintained in α-keratogenic layers of amniotes but decreased in β-keratogenic layers of sauropsids (reptiles and birds). The study suggests that similar proteins for the formation of the cornified cell envelope are present in α-keratinocytes across vertebrates but not in β-keratinocytes. © 2004 Wiley-Liss, Inc
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