Discovery and Genetic Characterization of a Vestimentiferan, Lamellibrachia satsuma, from the Submarine Volcano Omuro Dashi in the Izu-Ogasawara Arc.

Vestimentiferan tube worms (Annelida: Siboglinidae) were discovered in a hydrothermal field at a depth of 195 m in the crater of the submarine volcano Omuro Dashi in the Izu-Ogasawara Arc. Based on the nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene in individuals sampled in 2022, they were identified as Lamellibrachia satsuma Miura, Tsukahara & Hashimoto, 1997. STRUCTURE analysis and discriminant analysis of principal components (DAPC) based on 14 microsatellite markers showed a large genetic deviation of the population of Omuro Dashi from those of Kagoshima Bay and the north Mariana Arc (the Nikko and Daikoku Seamounts), whereas the population of Omuro Dashi did not show significant genetic deviation from that of the Nikko Seamount based on the COI gene. All analyses showed that individuals of a methane seep area on the Kanasu-No-Se Bank, the Nankai Trough, which were collected only in 1994, were more closely related to those of Omuro Dashi than to those of other habitats. These results suggest that the ancestors of the Omuro Dashi and Nankai Trough populations originated from migrants from the north Mariana Arc and that there might be undiscovered source population(s) of L. satsuma around the Nankai Trough.

Chiral Recognition of Diketopiperazine Containing Proline Residues by (-)-Epigallocatechin-3-O-gallate in Water.

The stoichiometry and precipitate yield of a complex of (-)-epigallocatechin-3-O-gallate (EGCg) and cyclo(Pro-Xxx) (Xxx = phenylalanine (Phe), tyrosine (Tyr)) were evaluated using integrated values of their proton signals by quantitative 1H-NMR (q NMR). It was determined to be a 1 : 1 complex of EGCg and cyclo(Pro-Xxx). The change in the chemical shift value of proton signals of cyclo(Pro-Xxx) in 1H-NMR spectra by adding standard amounts of EGCg was investigated. Differences in chemical shift values of H8α, H7αß, H8ß, H10, H9, and H3 proton signals between cyclo(L-Pro-L-Phe) and cyclo(D-Pro-D-Phe), and those of H8α, H7αß, H8ß, H10, H9, H3, and H13 proton signals between cyclo(L-Pro-L-Tyr) and cyclo(D-Pro-D-Tyr) were observed as a significant difference at 54 mmol/L of EGCg. It was found that their chirality was clearly recognized by EGCg. The significant difference in the change of the chemical shift value of H8α proton signals between cyclo(L-Pro-L-Xxx) and cyclo(D-Pro-D-Xxx) was the largest, and the difference was considered to have resulted from the difference in the ratio of extended conformer in equilibrium between folded and extended conformers. Such a significant difference in change values between cyclo(L-Pro-D-Xxx) and cyclo(D-Pro-L-Xxx) was not observed due to a rigid intramolecular CH-π interaction. EGCg did not clearly recognize the chirality of cyclo(L-Pro-D-Xxx) and cyclo(D-Pro-L-Xxx).

A novel liver-specific immunoglobulin heavy chain-like gene in a cartilaginous fish.

We identified a novel immunoglobulin (Ig) heavy chain-like gene (tsIgH) expressed in the liver of the banded houndshark Triakis scyllium by preliminary transcriptomic analysis. The tsIgH gene showed less than 30% of amino acid identities to Ig genes of the shark. The gene encodes one variable domain (VH) and three conserved domains (CH1-CH3) with a predicted signal peptide. Interestingly, this protein has only one cysteine residue in a linker region between VH and CH1 other than those required for the formation of the immunoglobulin domain. Genome sequencing revealed that each of the domains was encoded by a corresponding single exon, and the exon-intron structures of the homologues are conserved in the other cartilaginous fishes. By RT-qPCR analysis, the transcript of the tsIgH gene was observed only in the liver, while that of the IgM was mainly detected in the epigonal organ, liver, and spleen. The novel Ig-heavy chain-like gene in cartilaginous fish may provide new clues to the evolution of immunoglobulin genes.