Collagen colocalizes with a protein containing a decorin-specific peptide in the tissues of the ascidian Styela plicata

Ascidian (Chordata-Tunicata) Glycosaminoglycans: Extraction, Purification, Biochemical, and Spectroscopic Analysis

Sulfate polysaccharides with unique structures of the chondroitin/dermatan and heparin/heparan families of sulfated glycosaminoglycans have been described in several species of ascidians (Chordata-Tunicata). These unique sulfated glycans have been isolated from the ascidians and characterized by biochemical and spectroscopic methods. The ascidian glycans can be extracted by different tissues or cells by proteolytic digestion followed by cetylpyridinium chloride/ethanol precipitation. The total glycans are then fractionated by ion-exchange chromatography on DEAE-cellulose and/or Mono Q (HR 5/5) columns. Alternatively, precipitation with different ethanol concentrations can be employed. An initial analysis of the purified ascidian glycans is carried out by agarose gel electrophoresis on diaminopropane/acetate buffer, before or after digestion with specific glycosaminoglycan lyases or deaminative cleavage with nitrous acid. The disaccharides formed by exhaustive degradation of the glycans are purified by gel-filtration chromatography on a Superdex Peptide column and analyzed by HPLC on a strong ion-exchange Sax Spherisorb column. 1H- or 13C-nuclear magnetic resonance spectroscopy in one or two dimensions is used to confirm the structure of the intact glycans.

Biological function of unique sulfated glycosaminoglycans in primitive chordates

Glycosaminoglycans with unique sulfation patterns have been identified in different species of ascidians (sea squirts), a group of marine invertebrates of the Phylum Chordata, sub-phylum Tunicata (or Urochordata). Oversulfated dermatan sulfate composed of [4-α-L-IdoA-(2-O-SO₃)^-1 → 3-β-D-GalNAc(4-OSO₃)^-1]_n repeating disaccharide units is found in the extracellular matrix of several organs, where it seems to interact with collagen fibers. This dermatan sulfate co-localizes with a decorin-like protein, as indicated by immunohistochemical analysis. Low sulfated heparin/heparan sulfate-like glycans composed mainly of [4-α-L-IdoA-(2-OSO₃)^-1 → 4-α-D-GlcN(SO₃)^-1 (6-O-SO₃)^-1]_n and [4-α-L-IdoA-(2-O-SO₃)^-1 → 4-α-D-GlcN(SO₃)^-1]_n have also been described in ascidians. These heparin-like glycans occur in intracellular granules of oocyte assessory cells, named test cells, in circulating basophil-like cells in the hemolymph, and at the basement membrane of different ascidian organs. In this review, we present an overview of the structure, distribution, extracellular and intracellular localization of the sulfated glycosaminoglycans in different species and tissues of ascidians. Considering the phylogenetic position of the subphylum Tunicata in the phylum Chordata, a careful analysis of these data can reveal important information about how these glycans evolved from invertebrate to vertebrate animals.

Ascidian (Chordata-Tunicata) glycosaminoglycans: extraction, purification, biochemical, and spectroscopic analysis

Sulfated polysaccharides with unique structures of the chondroitin/dermatan and heparin/heparan families of sulfated glycosaminoglycans have been described in several species of ascidians (Chordata-Tunicata). These unique sulfated glycans have been isolated from-ascidians and characterized by biochemical and spectroscopic methods. The ascidian glycans can be extracted by different tissues or cells by proteolytic digestion followed by cetylpyridinium chloride/ethanol precipitation. The total glycans are then fractionated by ion-exchange chromatography on DEAE-cellulose and/or Mono Q (HR 5/5) columns. Alternatively, precipitation with different ethanol concentrations can be employed. An initial analysis of the purified ascidian glycans is carried out by agarose gel electrophoresis on diaminopropane/acetate buffer, before or after digestion with specific glycosaminoglycan lyases or deaminative cleavage with nitrous acid. The disaccharides formed by exhaustive degradation of the glycans is purified by gel-filtration chromatography on a Superdex-peptide column and analyzed by HPLC on a strong ion exchange Sax-Spherisorb column. 1H or 13C nuclear magnetic resonance spectroscopy in one or two dimensions is used to confirm the structure of the intact glycans.