Induction of cypris major protein in barnacle larvae by exposure to 4- n-nonylphenol and 17β-oestradiol

Abstract

Intense efforts are currently being made to develop procedures to assess the potential for endocrine disruption in aquatic environments. Most attention has focused on fresh water systems, amphibians and fish and morphological and molecular measures for endocrine disruption. A biomarker approach involving the induction of a female-specific protein, vitellogenin, in males by exposure to xeno-oestrogens has proved particularly useful. By contrast marine environments and invertebrates have received comparatively little attention. The present study aimed to examine the effects of exposure to a xeno-oetrogen, 4- n-nonylphenol (4-NP) and a natural oestrogen, 17β-oestradiol (E 2) on a marine crustacean, the barnacle Balanus amphitrite. In particular, the effect of such exposure on levels of a larval storage protein, cypris major protein (CMP), which is related to barnacle vitellin, has been examined. Accordingly, nauplius stage larvae of B. amphitrite were exposed to low concentrations (0.01–1.0 μg l −1) of 4-NP and E 2 (1.0 μg l −1) from egg hatching until the cypris stage. SDS–PAGE and immunoblotting were used to monitor CMP levels in exposed larvae relative to ‘zero’ concentration controls. Elevated (100% increase) CMP levels were measured in larvae exposed to both 4-NP and E 2 at a concentration of 1.0 μg l −1, and notable increases occurred at lower concentrations of 4-NP. It is concluded that CMP and perhaps other vitellin-like proteins are potential biomarkers of low level oestrogen exposure in crustaceans.