Nitrite released in haemocytes from Mytilus galloprovincialis, Crassostrea gigas and Ruditapes decussatus upon stimulation with phorbol myristate acetate

¹ Department of Zoology, Life Sciences Building, Guindy Campus, Chennai, 600 025 India
² UMR 219, CP 80, Université Montpellier II, 2 place E. Bataillon, 34095 Montpellier cedex 5, France

Received: 1 January 2000
Accepted: 11 April 2000

Abstract

In order to demonstrate the involvement of nitric oxide in the defence systems of marine bivalves, we investigated the production of superoxide and nitrite, following in vitro phorbol myristate acetate stimulation of Mytilus galloprovincialis, Crassostrea gigas and Ruditapes decussatus haemocytes. Whereas M. galloprovincialis and C. gigas haemocytes were found to produce superoxide and nitrite, R. decussatus haemocytes were found to be unable to generate either of these mediators. Nitrite is a stable end product of nitric oxide and peroxynitrite as well; it appeared therefore that some marine bivalves, to kill microbial pathogens, use NADPH-oxidase and nitric oxide-synthase pathways. This was confirmed at an experimental level where inhibitors of both enzymatic pathways blocked the production of nitrite. Moreover, this notion was strengthened by the inability of the haemocytes from R. decussatus, which cannot produce superoxide, to release nitrite when stimulated.