title: Dynamics of skeleton formation in the Lake Baikal sponge Lubomirskia baicalensis. Part II. Molecular biological studies.
abstract: In a preceding study it has been reported that the freshwater sponge Lubomirskia baicalensis, living in Lake Baikal (East Siberia), is composed of spicules forming a characteristic pattern which follows radiate accretive growth. Here we report that the spicules are synthesized by the enzyme silicatein, a protein which is related to cathepsin L. The cDNAs for silicatein and the related cathepsin L were isolated and used as probes to show that the mRNA levels of silicatein in the bases of the spicule skeleton of the animals are low, while the mRNA level of cathepsin L in this region exceeds that of the growing zone. This is the first comprehensive study on the importance of the axial filament/silicatein as an essential structural and functional component determining the growth and stability of demosponge spicules.
authors.affiliation: Limnological Institute of the Siberian Branch of Russian Academy of Sciences, Ulan-Batorskaya 3, RUS-664033, Irkutsk, Russia.
authors.forename: Oxana V
authors.initials: OV
authors.lastname: Kaluzhnaya
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Belikov
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.forename: Matthias
authors.initials: M
authors.lastname: Wiens
authors.forename: Marco
authors.initials: M
authors.lastname: Giovine
authors.forename: Anatoli
authors.initials: A
authors.lastname: Krasko
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Müller
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D056668:Cathepsin L; D002403:Cathepsins / Q000235:genetics; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000235:genetics; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D005618:Fresh Water; D008969:Molecular Sequence Data; D011161:Porifera / Q000235:genetics*; D012426:Russia
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D056668:Cathepsin L