title: First evidence of chitin as a component of the skeletal fibers of marine sponges. Part I. Verongidae (demospongia: Porifera).
abstract: The Porifera (sponges) are often regarded as the oldest, extant metazoan phylum, also bearing the ancestral stage for most features occurring in higher animals. The absence of chitin in sponges, except for the wall of peculiar resistance bodies produced by a highly derived fresh-water group, is puzzling, since it points out chitin to be an autapomorphy for a particular sponge family rather than the ancestral condition within the metazoan lineage. By investigating the internal proteinaceous (spongin) skeleton of two demosponges (Aplysina sp. and Verongula gigantea) using a wide array of techniques (Fourier transform infrared (FTIR), Raman, X-ray, Calcofluor White Staining, Immunolabeling, and chitinase test), we show that chitin is a component of the outermost layer (cuticle) of the skeletal fibers of these demosponges. FTIR and Raman spectra, as well as X-ray difractograms consistently revealed that sponge chitin is much closer to the alpha-chitin known from other animals than to beta-chitin. These findings support the view that the occurrence of a chitin-producing system is the ancestral condition in Metazoa, and that the alpha-chitin is the primitive form in animals.
authors.affiliation: Max Bergmann Center of Biomaterials, Institute of Materials Science, Dresden University of Technology, D-01069 Dresden, Germany. hermann.ehrlich@mailbox.tu-dresden.de
authors.forename: Hermann
authors.initials: H
authors.lastname: Ehrlich
authors.forename: Manuel
authors.initials: M
authors.lastname: Maldonado
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Spindler
authors.forename: Carsten
authors.initials: C
authors.lastname: Eckert
authors.forename: Thomas
authors.initials: T
authors.lastname: Hanke
authors.forename: René
authors.initials: R
authors.lastname: Born
authors.forename: Caren
authors.initials: C
authors.lastname: Goebel
authors.forename: Paul
authors.initials: P
authors.lastname: Simon
authors.forename: Sascha
authors.initials: S
authors.lastname: Heinemann
authors.forename: Hartmut
authors.initials: H
authors.lastname: Worch
mesh_terms: D000818:Animals; D002686:Chitin / Q000032:analysis*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D011161:Porifera / Q000737:chemistry* / Q000648:ultrastructure*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014961:X-Ray Diffraction
chemical_list: D002686:Chitin