New implications in the use of imposex as a suitable tool for tributyltin contamination: experimental induction in Hexaplex trunculus (Gastropoda, Muricidae) with different stressors

Abstract

Imposex, i.e. the development of additional male sex organs (penis and/or vas deferens), in females of gonochorist marine and freshwater gastropods, is known to be caused by tributyltin (TBT), and it has been widely used as a biomonitoring tool in environmental surveys for TBT pollution assessment. In this study, we experimentally tested the potential to induce imposex by another endocrine disruptor (polychlorinated biphenyls [PCBs] mixture--Aroclor 1260). Adults of Hexaplex trunculus with low imposex level, coming from an Italian Marine Protected Area, were injected separately with different doses of tributyltin chloride (TBTCl) and Aroclor 1260. The compounds were dissolved in ethanol and the organisms were narcotised by immersion in MgCl(2) solution before injection. Before and after the experiment, butyltin compounds (BuTs) and PCB tissue concentrations were determined. A significant increase in imposex with respect to non-treated organisms was observed in all treatments, including artefact controls. No clear correlation was observed between BuTs and PCB tissue concentrations and indices of imposex incidence. Based on these results, no assumption can be formulated about PCB effect on imposex development. Nevertheless, they suggest that the imposex level increase, at least in H. trunculus, in laboratory conditions might not be caused by TBT only, but it would rather be a non-specific response to different stress stimuli.

First record of butyltin body burden and imposex status in Hexaplex trunculus (L.) along the Tunisian coast

“…Concerning the RPSI, the highest degree of imposex found in the present study (RPSI ¼ 18.2%) was lower than that reported for the same species along the Italian Coast by Terlizzi et al 25 In males, it seems that TBT pollution may also impact secondary sexual organs. This observation suggests that factors other than TBT could be implicated on the development of imposex and thus agrees with recent findings reported by Garaventa et al 6 In fact, these authors have experimentally developed imposex in H. trunculus with stressors other than TBT, such as polychlorinated biphenyls (PCBs) and aroclor. However, significant correlations were only obtained for 2007 samples (r ¼ 0.6, p ¼ 0.2 in 2004 and r ¼ 0.8, p ¼ 0.04 in 2007).…”

“…However, significant correlations were only obtained for 2007 samples (r ¼ 0.6, p ¼ 0.2 in 2004 and r ¼ 0.8, p ¼ 0.04 in 2007). In fact, Garaventa et al 6 have studied a population already showing low levels of imposex, and consequently we ignore it if the contaminants used are able to induce imposex. In females, the relationship between TBT concentration and the incidence/degree of imposex was opposite in the stations of Sfax and Gab es fishing harbours, namely in 2004 samples.…”

Size matters: importance of penis length variation on reproduction studies and imposex monitoring in Bolinus brandaris (Gastropoda: Muricidae)

“…immersion in a solution of magnesium chloride until full relaxation), following the protocol proposed for N. lapillus by Gibbs (1999). Anaesthetisation with MgCl 2 has been successfully applied in several gastropod species (mainly for imposex studies), including other muricids such as Dicathais orbita (Noble et al, 2009), H. trunculus (Terlizzi et al, 2004;Vasconcelos et al, 2006;Garaventa et al, 2008), O. erinacea Huet et al, 1995;Gibbs, 1996), Stramonita haemastoma (Rilov et al, 2000) and specifically also in B. brandaris (Ramón & Amor, 2001Chiavarini et al, 2003;Gómez-Ariza et al, 2006). It is widely recognised that anaesthetisation causes the relaxation of the penial muscle, straightening the penis and increasing penis measurement.…”

Bioaccumulation of trace metals in Hexaplex trunculus: spatial and temporal trends from 2004 to 2011 along the Tunisian coast

“…trunculus is also considered an excellent bioindicator species of organotin pollution (TBT, tributyltin biocide used in antifouling paints), inducing the development of the sexual abnormality known as imposex (superimposition of penis and vas deferens onto females), which was described in several populations of this species throughout the Mediterranean (e.g., Martoja and Bouquegneau 1988;Axiak et al 1995;Terlizzi et al 1998;Lahbib et al 2009). Some studies reported the possible involvement of contaminants other than tributyltin in the development of imposex, such as copper, nonylphenol, polychlorinated biphenyls (PCBs), aroclor, and metals (Nias et al 1993;Evans et al 2000;Garaventa et al 2008;Lahbib et al 2009). Still, a recent study by Lahbib et al (2013) reported no evidence of relationships between Cu, Zn, and Cd contamination and imposex development in H. trunculus from the Tunisian coast.…”