Neuro-endocrine biomarkers of pollution-induced stress in marine invertebrates q

Nitric oxide NO. is a molecular mediator of the non-specific immune response of vertebrates but production has also been recorded in response to bacterial infection in invertebrates. Together with biogenic amines and cytokines, production of NO in invertebrate phagocytic haemocytes is thought to represent a putative stress response. In this study the hypothesis that NO might be a sensitive biomarker of stress in invertebrates has been tested. The spectrophotometric Griess assay for nitrite and nitrate has been modified so that the final breakdown products of NO are suitable for measurement in invertebrate haemolymph. The assay was linear in the range 1]100 mM with a sensitivity of 4 mM. The baseline NOx measurement in unstressed mussels was 0.74 mM NOxrmg protein. Mytilus edulis were kept at 158C in filtered seawater for at least 2 days prior to exposure to TBTO 0.001]0.1 mgrl. for 24 h. Preliminary results suggest that TBTO perturbs the NO response and that the outlined assay protocol is a sensitive means of detecting those changes. It is proposed that NO measurements potentially offer a highly sensitive, non-invasive means of monitoring stress responses associated with environmental change