Increasing efforts have been recently addressed to the evaluation of vitellogenin (Vg)-like protein induction as useful biomarker to assess estrogenic contamination in aquatic environments. Vg, the precursor of egg-yolk proteins, is normally synthesised in mature females, but is induced also in males and immature females of both fish and invertebrates after exposure to endocrine disrupting chemicals. Among these compounds, 4-nonylphenol (NP) is widespread in marine coastal areas, coming from various sources, mainly sewage treatment plants. In a previous study, NP was shown to induce Vg synthesis in pre-spawning males of the clam Tapes philippinarum after 7-days exposure, whereas no effect was detected in females (Matozzo and Marin, 2005). In the present work, estrogenic effects of NP were evaluated during sexual resting phase of clams, when gonads are undifferentiated and thus sex not distinguishable by microscopic observation of gonadal smears. Specimens of T. philippinarum from the Lagoon of Venice were exposed to the same NP concentrations previously tested (0, 0acetone, 0.0125, 0.025, 0.05, 0.1, 0.2 mg/l) for both 7 and 14 days. After exposure, Vg levels were determined in haemolymph and digestive gland by the alkali-labile phosphate (ALP) assay. In the haemolymph Ca2+ levels were also measured, they being possibly related to the presence of Vg-like proteins. In 7-days treatments, Vg content significantly increased in both haemolymph and digestive gland at the highest concentration tested (p< 0.05), whereas no variation was observed in haemolymph Ca2+ concentration. In 14-days treatments, Vg and Ca2+ levels showed a similar increasing trend in haemolymph, although significant differences with respect to controls were found at 0.025 and 0.05 mg NP/l for Ca2+ only (p< 0.05). A dose-dependent Vg increase was also observed in digestive gland, significant at 0.1 mg NP/l (p< 0.05). Responsiveness of Vg induction was confirmed in quiescent clams, mostly when measured in digestive gland, indicating applicability of the biomarker throughout the whole reproductive cycle of animals in both laboratory and field studies. A relationship between Vg and Ca2+ levels was detected in prolonged exposure only. Matozzo V., Marin M.G., 2005. Can 4-nonylphenol induce vitellogenin-like proteins in the clam Tapes philippinarum? Environ. Res., 91: 179-185. Acknowledgement This study was supported by grants from Co.Ri.La (Consortium for Coordination of Research Activities Concerning the Venice Lagoon System, Second Research Programme, 2004-2007).

Do reproductive conditions influence responsiveness of vitellogenin-like protein induction in clams (Tapes philippinarum) exposed to 4-nonylphenol?

MARIN, MARIA;MATOZZO, VALERIO
2007

Abstract

Increasing efforts have been recently addressed to the evaluation of vitellogenin (Vg)-like protein induction as useful biomarker to assess estrogenic contamination in aquatic environments. Vg, the precursor of egg-yolk proteins, is normally synthesised in mature females, but is induced also in males and immature females of both fish and invertebrates after exposure to endocrine disrupting chemicals. Among these compounds, 4-nonylphenol (NP) is widespread in marine coastal areas, coming from various sources, mainly sewage treatment plants. In a previous study, NP was shown to induce Vg synthesis in pre-spawning males of the clam Tapes philippinarum after 7-days exposure, whereas no effect was detected in females (Matozzo and Marin, 2005). In the present work, estrogenic effects of NP were evaluated during sexual resting phase of clams, when gonads are undifferentiated and thus sex not distinguishable by microscopic observation of gonadal smears. Specimens of T. philippinarum from the Lagoon of Venice were exposed to the same NP concentrations previously tested (0, 0acetone, 0.0125, 0.025, 0.05, 0.1, 0.2 mg/l) for both 7 and 14 days. After exposure, Vg levels were determined in haemolymph and digestive gland by the alkali-labile phosphate (ALP) assay. In the haemolymph Ca2+ levels were also measured, they being possibly related to the presence of Vg-like proteins. In 7-days treatments, Vg content significantly increased in both haemolymph and digestive gland at the highest concentration tested (p< 0.05), whereas no variation was observed in haemolymph Ca2+ concentration. In 14-days treatments, Vg and Ca2+ levels showed a similar increasing trend in haemolymph, although significant differences with respect to controls were found at 0.025 and 0.05 mg NP/l for Ca2+ only (p< 0.05). A dose-dependent Vg increase was also observed in digestive gland, significant at 0.1 mg NP/l (p< 0.05). Responsiveness of Vg induction was confirmed in quiescent clams, mostly when measured in digestive gland, indicating applicability of the biomarker throughout the whole reproductive cycle of animals in both laboratory and field studies. A relationship between Vg and Ca2+ levels was detected in prolonged exposure only. Matozzo V., Marin M.G., 2005. Can 4-nonylphenol induce vitellogenin-like proteins in the clam Tapes philippinarum? Environ. Res., 91: 179-185. Acknowledgement This study was supported by grants from Co.Ri.La (Consortium for Coordination of Research Activities Concerning the Venice Lagoon System, Second Research Programme, 2004-2007).
2007
14th MESAEP Symposium
9788484742142
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