Two cytotoxic peptides, yaku'amides A (1) and B (2), were isolated from the marine sponge Ceratopsion sp. Their planar structures were elucidated on the basis of spectroscopic data, whereas the absolute configurations were determined by a combination of the Marfey's analysis and dansylation analysis of the total and partial acid hydrolysis products. The growth inhibitory profile of yaku'amide A against a panel of 39 human cancer cell lines was clearly unique and distinguished from other anticancer drugs.

Cyclic peptides containing 5-hydroxytryptophan and thiazole moieties were isolated from the marine sponge Discodermia calyx collected near Shikine-jima Island, Japan. The structures of calyxamides A (1) and B (2), including the absolute configurations of all amino acids, were elucidated by spectroscopic analyses and degradation experiments. The structures are similar to keramamides F and G, previously isolated from Theonella sp. The analysis of the 16S rDNA sequences obtained from the metagenomic DNA of D. calyx revealed the presence of Candidatus Entotheonella sp., an unculturable δ-proteobacterium inhabiting the Theonella genus and implicated in the biosynthesis of bioactive peptides.

Six linear acetylenes, (-)-duryne (1) and (-)-durynes B-F (2-6), were isolated from the marine sponge Petrosia sp. Their structures were elucidated by NMR and tandem FABMS analyses. The positions of the olefinic bonds were confirmed by ozonolysis experiments, and the absolute configurations were determined by the modified Mosher's method. Compound 1 was found to be the enantiomer of duryne, a previously reported sponge metabolite. Compounds 1-6 show cytotoxicity against HeLa cells with IC50 values between 0.08 and 0.50 μM.

We investigated microorganisms associated with a deep-sea sponge, Characella sp. (Pachastrellidae) collected at a hydrothermal vent site (686 m depth) in the Sumisu Caldera, Ogasawara Island chain, Japan, and with two sponges, Pachastrella sp. (Pachastrellidae) and an unidentified Poecilosclerida sponge, collected at an oil seep (572 m depth) in the Gulf of Mexico, using polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE) directed at bacterial 16S rRNA gene sequences. In the PCR-DGGE profiles, we detected a single clearly dominant band in each of the Characella sp. and the unidentified Poecilosclerida sponge. BLAST search of their sequences showed that they were most similar (>99% identity) to those of the gammaproteobacterial thioautotrophic symbionts of deep-sea bivalves from hydrothermal vents, Bathymodiolus spp. Phylogenetic analysis of the near-full length sequences of the 16S rRNA genes cloned from the unidentified Poecilosclerida sponge and Characella sp. confirmed that they were closely related to thioautotrophic symbionts. Although associations between sponges and methanotrophic bacteria have been reported previously, this is the first report of a possible stable association between sponges and thioautotrophic bacteria.Electronic supplementary materialThe online version of this article (doi:10.1007/s10126-009-9253-7) contains supplementary material, which is available to authorized users.