Ionic and Osmotic Influences on Prostaglandin Release from the Gill Tissue of A Marine Bivalve, Modiolus Demissus

Abstract

1. Prostaglandin E2 (PGE2) was identified in Modiolus demissus gill tissue on the basis of solvent extraction, thin layer and column chromatography, bioassay, and radioimmunoassay. The presence of PGE2 was detected in both tissue and sea water incubate surrounding the tissue. 2. Both hyposmotic stress and magnesium-free sea water significantly increased release of prostaglandins into sea water. Hyposmotic stress also significantly increased prostaglandin synthesis. 3. Examination of tissues revealed that homogenates of the mantle and lower visceral mass contained significantly fewer nanograms immunoreactive prostaglandins per gram wet weight than homogenates of the gill, posterior adductor muscle, upper visceral mass, or siphon tissue. 4. Prostaglandin release could be increased by addition of arachidonic acid, and inhibited by addition of acetylsalicylic acid or indomethacin.

Carbocyclic oxylipins of marine origin

“…)-PGA2 33-36 by their incorporation into agar strips.65 These were attached to ropes anchored in a tropical reef ecosystem. Both of the partially esterified forms (35 and 36) as well as free (15-R)-PGA2 (33) showed significant antifeedant activity while the fully esterified form 34 did not. However, this latter result was less certain due to a poor recovery of test agar strips.…”

“…The discovery that prostaglandins are produced by corals was initiated by the finding of (15i? )-PGA2 (33) and methyl 15(i? )-acetoxy-PGA2 (34) in the Caribbean gorgonian Plexaura homomalla forma homomalla.…”

“…Another mollusc, the bivalve Modiolus demissus, was suggested to contain PGA derivatives as determined by reaction with anti-PGB following reaction with dilute KOH. 33 Prostanoid production in molluscs appears to be involved in osmotic regulation33'68 and, by virtue of its inhibition with aspirin or indomethacin, produced via prostaglandin H synthase as in mammals. A lowaffinity PGA2 binding site has been described from M. demissus.…”

“…69 The red alga Gracilaria verrucosa was a source of small amounts of PGA2 ( 16); however, this may be a dehydration artifact of the more major metabolite in the alga, PGE2 (14, see above).26 Proposed biosynthesis of (15f? )-prostaglandin A2 (33) by the Caribbean octocoral Plexaura homomalla (from ref 5).…”

Untargeted Metabolomics Reveals a Complex Impact on Different Metabolic Pathways in Scallop Mimachlamys varia (Linnaeus, 1758) after Short-Term Exposure to Copper at Environmental Dose

“…These variations potentially correspond to disturbance of biological functions such as reproduction, ion transport and defence caused by copper in scallops. PGE2 was shown to be involved in sodium transport regulation in gills of the freshwater mussel Ligumia subrostrata and in clams [73] and it was shown that hyposmotic stress significantly increased PG synthesis in the marine bivalve Modiolus demissus [74]. This is the second time that PG-glutathione conjugates are described in clams, showing that these compounds are indeed present in bivalves and that they are affected by metals [11].…”