Discovery of an 11(R)‐ and 12(S)‐lipoxygenase activity in ovaries of the mussel Mytilus edulis

Abstract

Eicosanoid biosynthesis was investigated in mussel gonads by incubation of tissue homogenates with radiolabeled arachidonic acid and analysis of the products by radio-high-performance liquid chromatography. No radiolabeled metabolites were formed in homogenates of testes, but two major metabolites were synthesized by ovarian preparations. The radiolabeled metabolites were analyzed by mass spectrometry and chiral chromatography and identified as 11 (R)-hydroxy-5,8,1 2,14-eicosatetraenoic acid and 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid. In addition, four other nonlabeled metabolites, formed from endogenous substrates, were detected in ovarian extracts. Their structures, determined by mass spectrometric analysis, were the corresponding 11- and 12-hydroxy analogs formed from eicosapentaenoic acid (11-HEPE and 12-HEPE) and 9-hydroxy-6,10,12,15-octadecatetraenoic acid (9-HOTE) and 13-hydroxy-6,9,11,15-octadecatetraenoic acid formecl from stearidonic acid. The biosynthesis of the 11 - and 12-hydroxy products was calcium dependent, localized to the 100,000 x g supernatant cell fraction, and was inhibited by nordihydroguaiaretic acid, but not inhibited by the prostaglandin synthase inhibitors aspirin and indomethacin, or the monoxygenase inhibitor proadifen. Together these data suggested that both the 11 (R)- and 12(S)-hydroxy products were formed from lipoxygenase-type enzymes. Incubation of homogenates of immature ovaries with eicosapentaenoic acid revealed the major product to be I2-HEPE, whereas in mature ovaries mainly 11-HEPE was formed. Extraction of spawned eggs with methanol revealed that predominantly 11-HEPE and 9-HOTE were formed from endogenous substrates. This study shows that female gonads of the mussel express an 11(R)- and 12(S)-lipoxygenase activity whose expression is dependent on differentiation of the ovary.

Sexual Differences in Gonad Fatty Acid Compositions in Dominant Limpets Species from the Sanriku Coast in Northern Japan.

“…The present differences in fatty acid compositions in the testis and ovary of limpets according to sex may be to a clue for understanding not only the reproductive cycle in marine invertebrates but also mechanisms of biologically active lipid metabolites known as eicosanoids that are essential to reproductive physiology (12)(13)(14).…”

Evolutionary aspects of lipoxygenases and genetic diversity of human leukotriene signaling

“…Invertebrates include multiple groups of living organisms such as insect, crap, lobster, snail, clam, octopus, starfish, sea urchin, worm and sponge. Functional LOX isoforms from various invertebrates have been characterized as fusion or nonfusion proteins in different corals [135][136][137][138][139][140], in starfish oocytes [141], in the eggs of a sea urchin [142] and in the ovaries and oocytes of different mussels (Mylitis edulis, Spisula solidissima) [143,144]. Recently the distribution of LOX isoforms in 14 different invertebrate species was explored [145] and the authors found putative LOX-like sequences in 10 of them (Ciona intestinalis, Saccoglossus kowalevski, Strongylocentrotus purpuratus, Crassostrea gigas, Lottia gigantea, Capitella teleta, Helobdella robusta, Acropora digitifera, Nematostella vectensis, Trichoplax adhaerens).…”

Characterization and Immobilization of Marine Algal 11‐Lipoxygenase from Ulva fasciata

“…The 2,4-decadienals of marine algal volatile compounds have been suggested to be produced via 11-hydroperoxyicosatetraenoic acid (HPITE) from arachidonic acid in marine green algal 11-LOX pathway [9]. The 11-HPITE has also been named in our studies as well as in other literatures [6,10].…”