Larval Development and Vitellin-like Protein Expression in Palaemon elegans Larvae Following Xeno-oestrogen Exposure

Certain anthropogenic chemicals, most notably xeno-oestrogens,are known to have the potential to disrupt vertebrate endocrinesystems. For example, induction of the female-specific protein,vitellogenin, in male fish is a well-known effect of exposureto xeno-oestrogens and serves as a biomarker of such exposure.There have been few comparable studies of putative biomarkersof endocrine disruption in invertebrates. An exception is theupregulation of vitellin-like larval storage protein (LSP) expressionin the barnacle cypris larva following exposure to oestrogenicchemicals. The current study aimed to establish whether larvaeof the glass prawn, Palaemon elegans, are likewise susceptibleto xeno-oestrogen exposure. Using a polyclonal antiserum toP. elegans apolipovitellin, an 86 kDa polypeptide was detectedby western blotting in the larval and early postlarval stagesof this species. An indirect ELISA applied to the soluble proteinfraction of larval homogenates determined that the titre ofthis putative LSP ranged, depending on larval stage, from 0.48–0.67ng µg^–1. Exposure of P. elegans larvae to the xeno-oestrogen4-n-nonylphenol (4-NP), at 0.2–20 µg L^–1,resulted in a significant, concentration-independent increasein putative LSP levels of 5–18%. Conversely, exposureto the natural oestrogen, 17ß-oestradiol (E₂), at0.2 and 20 µg L^–1, led to a significant concentration-independentdecline (up to 11%) in LSP levels. Whether the effect of 4-NPresults from endocrine disruption is not known, however, anoestrogen receptor-mediated effect is unlikely. Other than aslight increase in larval mortality when exposed to 4-NP at2 µg L^–1, neither 4-NP nor E₂ significantly affecteddevelopment, growth or survival of P. elegans larvae.