0000000000312442
AUTHOR
Alexandra Borejko
Formation of layered titania and zirconia catalysed by surface-bound silicatein
Silicatein immobilised on self-assembled polymer layers using a histidine-tag chelating anchor group retains its hydrolytical activity for the formation of biosilica, and catalyses the formation of layered arrangements of biotitania and biozirconia.
Axial (apical-basal) expression of pro-apoptotic and pro-survival genes in the lake baikal demosponge Lubomirskia baicalensis.
Like in all other Metazoa, also in sponges (Porifera) proliferation, differentiation, and death of cells are controlled by apoptotic processes, thus allowing the establishment of a Bauplan (body plan). The demosponge Lubomirskia baicalensis from the Lake Baikal is especially suitable to assess the role of the apoptotic molecules, since its grade of construction is highly elaborated into an encrusting base and branches composed of modules lined up along the apical-basal axis. The four cDNAs, ALG-2, BAK, MA-3, and Bcl-2, were isolated from this sponge species. The expression levels of these genes follow characteristic gradients. While the proapoptotic genes are highly expressed at the base of…
Novel mechanism for the radiation-induced bystander effect: nitric oxide and ethylene determine the response in sponge cells.
Until now the bystander effect had only been described in vertebrates. In the present study the existence of this effect has been demonstrated for the phylogenetically oldest metazoan phylum, the Porifera. We used the demosponge Suberites domuncula for the experiments in the two-chamber-system. The lower dish contained irradiated "donor" cells (single cells) and the upper dish the primmorphs ("recipient" primmorphs). The "donor" cells were treated with UV-B light (40 mJ/cm2) and 100 microM hydrogen peroxide (H2O2), factors that exist also in the natural marine aquatic environment of sponges; these factors caused a high level of DNA strand breaks followed by a reduced viability of the cells.…
Selenium affects biosilica formation in the demosponge Suberites domuncula
Selenium is a trace element found in freshwater and the marine environment. We show that it plays a major role in spicule formation in the demosponge Suberites domuncula. If added to primmorphs, an in vitro sponge cell culture system, it stimulates the formation of siliceous spicules. Using differential display of transcripts, we demonstrate that, after a 72-h exposure of primmorphs to selenium, two genes are up-regulated; one codes for selenoprotein M and the other for a novel spicule-associated protein. The deduced protein sequence of selenoprotein M (14 kDa) shows characteristic features of metazoan selenoproteins. The spicule-associated protein (26 kDa) comprises six characteristic repe…