New insights into the mechanism of imposex induction in the dogwhelk Nucella lapillus

Santos, Miguel M.; Castro, L. Filipe C.; Vieira, Maria Natividade; Micael, Joana; Morabito, Roberto; Massanisso, P.; Reis-Henriques, M.A.

doi:10.1016/j.cca.2005.05.008

Cited by 50 publications

(46 citation statements)

References 33 publications

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“…The microsomal enzyme that conjugates testosterone to fatty acids has been designated as acyl coenzyme A:testosterone acyltransferase (ATAT). Since these initial observations, this same process for regulating free hormone levels has been documented in other gastropods for both testosterone and 17b-estradiol (Janer et al 2005c(Janer et al , 2006bSantos et al 2005;Sternberg et al 2008a). Collectively, these metabolic studies indicate that gastropods are capable of biosynthesizing and biotransforming the sex steroids that are present in their tissues.…”

Section: Hormones Of the Reproductive Neuro-endocrine Cascadementioning

confidence: 86%

Environmental-endocrine control of reproductive maturation in gastropods: implications for the mechanism of tributyltin-induced imposex in prosobranchs

et al. 2009

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Prosobranch snails have been afflicted globally by a condition whereby females develop male sex characteristics, most notably a penis. This condition, known as imposex, has been causally associated with the ubiquitous environmental contaminant tributyltin (TBT). Deduction of the mechanism by which TBT causes imposex has been hampered by the lack of understanding of the normal endocrine regulation of reproductive tract recrudescence in these organisms. We have reviewed the relevant literature on the environmental and endocrine factors that regulate reproductive tract recrudescence, sexual differentiation, and reproduction in gastropods. We provide a cohesive model for the environmental-endocrine regulation of reproduction in these organisms, and use this information to deduce a most likely mechanism by which TBT causes imposex. Photoperiod appears to be the predominant environmental cue that regulates reproductive tract recrudescence. Secondary cues include temperature and nutrition which control the timing of breeding and egg laying. Several hormone products of the central and peripheral nervous systems have been identified that contribute to recrudescence, reproductive behaviors, oocyte maturation and egg laying. Retinoic acid signaling via the retinoid X-receptor (RXR) has shown promise to be a major regulator of reproductive tract recrudescence. Furthermore, TBT has been shown to be a high affinity ligand for the RXR and the RXR ligand 9-cis retinoic acid causes imposex. We propose that TBT causes imposex through the inappropriate activation of this signaling pathway. However, uncertainties remain in our understanding of the environmental-endocrine regulation of reproduction in gastropods. Definitive elucidation of the mechanism of action of TBT awaits resolution of these uncertainties.

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Section: Hormones Of the Reproductive Neuro-endocrine Cascadementioning

confidence: 86%

Environmental-endocrine control of reproductive maturation in gastropods: implications for the mechanism of tributyltin-induced imposex in prosobranchs

et al. 2009

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“…Experiments focussing on the pharmacological elimination or blocking of sex steroid receptors have suggested that receptor-mediated sex steroid signalling occurs in the gastropod Nucella lapillus, and the scallop Placopecten magellanicus (Bettin et al, 1996;Santos et al, 2005;Wang and Croll, 2003). Although these studies indicate the presence of sex steroid receptors they do not offer evidence about molecular receptor structures.…”

Section: (Neuro-)endocrine Control In Molluscsmentioning

confidence: 99%

“…T levels in females without imposex were always lower than in females with imposex, and the T/E2 ratio tended to increase with increasing imposex and organotin contamination. Santos et al (2005) used N. lapillus from an almost imposex-free population, and TBT at a concentration of 50 ng as Sn/L as positive control. The same CYP19 inhibitor as in the study of Bettin et al (1996) was applied at the identical concentration and again induced imposex, whereas CPA blocked the capacity of TBT to induce imposex.…”

Section: Modes Of Action Of Endocrine Disrupting Chemicals (Edcs) In mentioning

confidence: 99%

Detailed Review Paper (DRP) on Molluscs Life-cycle Toxicity Testing

2014

OECD Series on Testing and Assessment

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No.107 Preservative treated wood to the environment for wood held in storage after treatment and for wooden commodities that are not cover and are not in contact with ground. (2009) No.108 Report of the validation of the Hershberger Bioassay (weanling model) (2009) No. 109 Literature review on the 21-Day Fish Assay and the Fish Short-Term Reproduction Assay (2009) No. 110 Report of the validation peer review for the weanling Hershberger Bioassay and agreement of the working of national coordinators of the test guidelines programme on the follow-up of this report (2009) No. 111 Report of the Expert Consultation to Evaluate an Estrogen Receptor Binding Affinity Model for Hazard Identification (2009) No. 112 The 2007 OECD List of High Production Volume Chemicals (2009) No. 113 Report of The Focus Session On Current And Forthcoming Approaches For Chemical Safety And Animal Welfare (2010) No. 114 Performance Assessment of Different Cytotoxic and Cytostatic Measures for the In Vitro Micronucleus Test (MNVIT): Summary of results in the collaborative trial (2010) No. 115 Guidance Document on the Weanling Hershberger Bioassay in Rats: A Short-term Screening Assay for (Anti)E About the OECDThe Organisation for Economic Co-operation and Development (OECD) is an intergovernmental organisation in which representatives of 31 industrialised countries in North and South America, Europe and the Asia and Pacific region, as well as the European Commission, meet to co-ordinate and harmonise policies, discuss issues of mutual concern, and work together to respond to international problems. Most of the OECD's work is carried out by more than 200 specialised committees and working groups composed of member country delegates. Observers from several countries with special status at the OECD, and from interested international organisations, attend many of the OECD's workshops and other meetings. Committees and working groups are served by the OECD Secretariat, located in Paris, France, which is organised into directorates and divisions. IV.Although there are some similarities between the endocrine systems of vertebrates and molluscs, the lack of knowledge about how EDCs act in molluscs currently prevents the use of mollusc-based tests as surrogates for tests with aquatic vertebrates such as fish.V. Given our relatively poor understanding of molluscan endocrinology, it is not currently possible to recommend the development of mollusc-based screening tests for the identification of EDCs. On the other hand, we are now in a position to start standardising apical mollusc tests involving partial or full lifecycle exposures. In principle, these are expected to be responsive to any chemicals (EDCs or nonEDCs) with activity in molluscs, even though they may not provide diagnostic information on modes of action (MoA). VI.The review recommends three apical test procedures for optimisation and possible validation. The first is a partial life cycle (PLC) test with the freshwater gastropod Potamopyrgus antipodarum, the second is a full li...

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“…For some species, such as Nassarius reticulates and Ilyanassa obsolata, the reproductive activity of the imposex females appeared not to be affected, while in other species, such as Nucella lapillus and Thais clavigera Horiguchi et al, 1994), the developing vas deferens may block the oviduct opening (vulva), resulting in the sterilization of the females due to the failure in egg capsule release . Previously, there were various proposed mechanisms of this endocrine disruption (Matthiessen and Gibbs, 1998), including the aromatase inhibition hypothesis (Spooner et al, 1991;Bettin et al, 1996;Santos et al, 2005), testosterone excretion-inhibition hypothesis (Ronis and Mason, 1996), neuroendocrine system disruption hypothesis (Féral and LeGall, 1983) and the APGWamide hypothesis McClellan-Green, 2000, 2002). Among them, the aromatase inhibition hypothesis tended to receive more attention (Spooner et al, 1991;Bettin et al, 1996;Oehlmann et al, 1996a).…”

Section: Introductionmentioning

confidence: 99%

Ecological risk assessments of endocrine disrupting organotin compounds using marine neogastropods in Hong Kong

Leung

Kwong

et al. 2006

Chemosphere

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As active ingredients of anti-fouling paints that are widely used on ship hulls, organotin compounds, in particular tributyltin (TBT), are well-known endocrine disruptors causing sex changes in marine organisms and widespread in coastal waters and sediments worldwide. In this study, a comprehensive ecological risk assessment (ERA) of organotins was conducted in Hong Kong waters through determining the imposex status, sex ratio and tissue burdens of these compounds in the neogastropods, Thais clavigera and Thais luteostoma collected from 29 coastal sites. We also investigated the historical trend of organotin effects on these gastropods, and performed a probabilistic ERA based on tissue burden of TBT in the animals. Our results demonstrated that imposex indices were positively correlated with the body burden of organotins in the gastropods. Across all sites, the sex ratio (female:male) decreased significantly with increasing imposex levels or tissue burden of organotins, implying that such pollutants can result in a male-biased population, potentially leading to local extinction in extreme cases. Based on the ERA, 5.4% of all populations of T. clavigera are at risk due to exposure to TBT; the risks include growth inhibition, impairment of immune functions and reduced fitness. Seriously impacted areas included Aberdeen, Repulse Bay, Butterfly Beach, Mui Wo and Ha Mei Wan. A comparison with historical data revealed that there had been some improvement in the areas with low marine traffic, and distant from the major harbour/port. This could partly be due to the restriction on the use of TBT on small vessels (<25 m in length) since 1992. Nevertheless, the organotin contamination still remains severe in areas with high marine traffic or adjacent to large harbours/ports. In particular, the situation in the northeastern waters of Hong Kong has been getting worst since 1996 that is probably associated with the rapid development of the cargo container port at Yantian in China.

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New insights into the mechanism of imposex induction in the dogwhelk Nucella lapillus

Cited by 50 publications

References 33 publications

Environmental-endocrine control of reproductive maturation in gastropods: implications for the mechanism of tributyltin-induced imposex in prosobranchs

Environmental-endocrine control of reproductive maturation in gastropods: implications for the mechanism of tributyltin-induced imposex in prosobranchs

Detailed Review Paper (DRP) on Molluscs Life-cycle Toxicity Testing

Ecological risk assessments of endocrine disrupting organotin compounds using marine neogastropods in Hong Kong

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