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A fucosylated chondroitin sulfate from echinoderm modulates in vitro fibroblast growth factor 2-dependent angiogenesis.

Fucosylated chondroitin sulfate (FucCS), a glycosaminoglycan obtained from sea cucumber, has the same structure as mammalian chondroitin sulfate, but some of the glucuronic acid residues display sulfated fucose branches. This new polysaccharide has a more favorable effect than heparin on vascular cell growth. It inhibits smooth muscle cell proliferation as heparin, and it has a potent enhancing effect on endothelial cell proliferation and migration in the presence of heparin-binding growth factors. We now extend our studies to the effect of this glycosaminoglycan on endothelial cells to an in vitro angiogenesis model on Matrigel. FucCS, in the presence of fibroblast growth factor-2 (FGF-2), strongly increases the capacity of endothelial cells to form vascular tubes on Matrigel with a well-organized capillary-like network and typical closed structures. Comparison between the activity of native and chemically modified chondroitin sulfate from sea cucumber reveals that the sulfated fucose branches are the structural motif for the proangiogenic activity. Heparin does not induce angiogenesis in this experimental model. We also have evidence for the proposition that endothelial cell proliferation is not the sole event involved in the in vitro FGF-2-induced angiogenesis. It implies a variety of other modifications of the endothelial cells and of their interaction with the extracellular matrix, such as integrin expression and actin cytoskeleton reorganization. Finally, the proangiogenic effect of FucCS, concomitant with its capacity to prevent venous and arterial thrombosis, in animal models makes this new glycosaminoglycan a promising molecule with possible beneficial effects in pathological conditions affecting blood vessels such as the neovascularization of ischemic areas.

Actins↗

[A comparative study of the biogenic amine receptors in the muscle tissue of mollusks, echinoderms and tunicates].

Smooth muscles of Mollusca, Echinodermata and Tunicata contain one class of adrenoreceptors with the dissociation constant and maximal specific binding 2.5 and 82 in Anodonta, 2.3 and 320 in Holothuria, 4.9 pM and 232.5 fmol/mg of protein in ascidia. Catecholamines and their antagonists can be ranged in the row as follows: isoproterenol greater than adrenalin greater than propranolol-noradrenaline greater than phentolamine. Negative regulation of the beta-adrenoreceptor affinity to isoproterenol by means of guanine nucleotides (GN) was shown. The muscular tissues of Mollusca, Echinodermata and Tunicata have only one class of the serotonin receptors with the dissociation constant and maximal specific binding 120 and 13.2 in Anodonta, 88 and 192 in Holothuria, 2.6 pM and 54 fmol/mg of protein in ascidia. The GTP negative regulation of serotonin receptors affinity to the hormone was found. The GN regulation of the above receptors affinity to agonist suggests that muscle tissue of the above species has specific GTP [correction of GTR]-binding proteins capable of coupling with these receptors.

Animals↗

Relationship between basic proteins associated to DNA and replication during early development of Echinoderms.

A close relationship between histone synthesis and DNA replication has been suggested for many biological systems. The presence of histonic proteins has been demonstrated in practically all kinds of eukaryotic cells. During the clevage period of sea urchins it has been postulated that histones are not present in nuclei, and that only at blastula stage they do associate with DNA. Our results suggest that the failure to isolate histonic proteins from nuclei derived from cleavage cells might be caused by the presence in those cells of proteases activated by NaHSO3. This compound has being widely used to inhibit proteolytic action in other biological systems. By changing the method for chromatin isolation, we have been able to isolate basic proteins from nuclei of gametes, zygotes and 2-4 blastomeres. These proteins behave like calf thymus histones in urea-acetic acid polyacrylamide gels, and they do not show great differences from proteins isolated from nuclei of blastula, gastrula, prism, and pluteus. The electrophoretic patterns of basic proteins obtained from eggs and zygotes are practically identical, except for one protein moving like lysine-rich calf thymus histones. This protein appears in zygote nuclei at the beginning of the first replication wave.

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