BACKGROUND: Spicules, the siliceous skeletal elements of the siliceous sponges, are synthesized enzymatically via silicatein. The product formed, bio-silica, constitutes their inorganic matrix. It remained unexplored which reactions are involved in molding of the amorphous bio-silica and formation of a solid and rigid biomaterial. METHODS: Cell and molecular biological techniques have been applied to analyze processes resulting in the hardening of the enzymatically synthesized bio-silica. The demosponge Suberites domuncula has been used for the studies. RESULTS: Cell aggregates (primmorphs) from the sponge S. domuncula, grown in the presence of Mn-sulfate, form spicules that comprise, instead of a smooth, a rough and porous surface which is decorated with irregular bio-silica deposits. During this process, the expression of the aquaporin-8 gene becomes down-regulated. Further in vitro studies showed that aquaporin is required for dehydration, and hardening of bio-silica following its enzymatic formation. The data show that in cell aggregates grown in the presence of Mn-sulfate, aquaporin-8 is down-regulated. We conclude that in cell aggregates grown in the presence of Mn-sulfate, the removal of reaction water, produced during the bio-silica polycondensation reaction, is inhibited. GENERAL SIGNIFICANCE: This study highlights that besides the silicatein-driven polycondensation reaction, the spicule formation also requires a phase of syneresis that results in a hardening of the material. 2011 Elsevier B.V. All rights reserved.
BACKGROUND: Spicules, the siliceous skeletal elements of the siliceous sponges, are synthesized enzymatically via silicatein. The product formed, bio-silica, constitutes their inorganic matrix. It remained unexplored which reactions are involved in molding of the amorphous bio-silica and formation of a solid and rigid biomaterial. METHODS: Cell and molecular biological techniques have been applied to analyze processes resulting in the hardening of the enzymatically synthesized bio-silica. The demosponge Suberites domuncula has been used for the studies. RESULTS: Cell aggregates (primmorphs) from the sponge S. domuncula, grown in the presence of Mn-sulfate, form spicules that comprise, instead of a smooth, a rough and porous surface which is decorated with irregular bio-silica deposits. During this process, the expression of the aquaporin-8 gene becomes down-regulated. Further in vitro studies showed that aquaporin is required for dehydration, and hardening of bio-silica following its enzymatic formation. The data show that in cell aggregates grown in the presence of Mn-sulfate, aquaporin-8 is down-regulated. We conclude that in cell aggregates grown in the presence of Mn-sulfate, the removal of reaction water, produced during the bio-silica polycondensation reaction, is inhibited. GENERAL SIGNIFICANCE: This study highlights that besides the silicatein-driven polycondensation reaction, the spicule formation also requires a phase of syneresis that results in a hardening of the material. 2011 Elsevier B.V. All rights reserved.
Authors: Werner E G Müller; Heinz C Schröder; Julia S Markl; Vlad A Grebenjuk; Michael Korzhev; Renate Steffen; Xiaohong Wang Journal: J Histochem Cytochem Date: 2013-08-06 Impact factor: 2.479
Authors: Heinz C Schröder; Xiaohong Wang; Alberto Manfrin; Shu-Hong Yu; Vlad A Grebenjuk; Michael Korzhev; Matthias Wiens; Ute Schlossmacher; Werner E G Müller Journal: J Biol Chem Date: 2012-04-27 Impact factor: 5.157
Authors: Xiaohong Wang; Matthias Wiens; Heinz C Schröder; Ute Schlossmacher; Dario Pisignano; Klaus Peter Jochum; Werner E G Müller Journal: PLoS One Date: 2011-06-02 Impact factor: 3.240
Authors: Matthias Wiens; Heinz C Schröder; Michael Korzhev; Xiao-Hong Wang; Renato Batel; Werner E G Müller Journal: Mar Drugs Date: 2011-10-19 Impact factor: 6.085