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How to Produce a Chemical Defense: Structural Elucidation and Anatomical Distribution of Aplysioviolin and Phycoerythrobilin in the Sea Hare Aplysia californica
Author(s) -
Kamio Michiya,
Nguyen Linh,
Yaldiz Seymanur,
Derby Charles D.
Publication year - 2010
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.201000006
Subject(s) - aplysia , phycobiliprotein , phycoerythrin , chemistry , chemical defense , covalent bond , natural product , biology , biochemistry , botany , organic chemistry , cyanobacteria , microbiology and biotechnology , flow cytometry , genetics , herbivore , evolutionary biology , bacteria
We previously used bioassay‐guided fractionation to identify phycoerythrobilin ( 1 ) and its monomethyl ester, aplysioviolin ( 2 ), as components in the ink secretion of a marine gastropod, the sea hare Aplysia californica , that act as chemical deterrents against predatory blue crabs. This was the first report of 1 as a natural product. Compound 2 was previously reported as a natural product from three species of Aplysia ( A. fasciata, A. dactylomela , and A. parvula ), but the reported structure and composition of stereoisomers of 2 are different among these species. Sea hares are thought to produce 2 from phycoerythrin, a photosynthetic pigment in their red‐algal diet composed of a phycobiliprotein covalently linked to the chromophore 1 , by cleavage of the covalent bond and methylation of 1 , but neither the sequence nor the anatomical location of the cleavage and methylation is known. In this study, we clarify the structure of 1 and 2 in ink secretion of A. californica , and describe the distribution of 1 and 2 in the tissues of sea hares. We conclude that cleavage of the covalent bond in phycoerythrin occurs first, forming 1 in the digestive gland, followed by methylation of 1 to yield 2 in the ink gland.