The Experts below are selected from a list of 535902 Experts worldwide ranked by ideXlab platform
Jörg Oehlmann - One of the best experts on this subject based on the ideXlab platform.
-
Prosobranch snails as test organisms for the assessment of endocrine active chemicals--an overview and a guideline proposal for a reproduction test with the freshwater mudsnail Potamopyrgus antipodarum.
Ecotoxicology, 2007Co-Authors: Martina Duft, Claudia Schmitt, Cornelius Brandelik, Ulrike Schulte-oehlmann, Jean Bachmann, Jörg OehlmannAbstract:Recently, prosobranch snails have been recommended as promising candidates for test organisms for the assessment of endocrine active chemicals. Three prosobranch snail species, the freshwater mudsnail Potamopyrgus antipodarum, the freshwater ramshorn snail Marisa cornuarietis, and the marine netted whelk Nassarius reticulatus are portrayed and their respective biotests are presented together with results of laboratory experiments and biological effect monitoring surveys in the field. All characterized species are highly sensitive toward xeno-androgens [triphenyltin (TPT), tributyltin (TBT), methyltestosterone (MT) and fenarimol (FEN)], and xeno-estrogens [bisphenol A (BPA), octylphenol (OP), ethinylestradiol], and show effects at environmentally relevant, rather low concentrations in laboratory experiments. For exposure to the xeno-androgen TPT, EC10 values range between 15.9 and 29.0 ng as Sn/L (sediment 0.03 μg as Sn/kg), for TBT, EC10 values are found between 3.42 and 37.8 ng as Sn/L (sediment 2.98 μg as Sn/kg) and effect concentrations for FEN are calculated as 18.6 ng/L (EC10) and 0.19 μg/kg (EC50 sediment; EC10 not calculable). Exposure to xeno-estrogens yielded EC10 values of 13.9 ng/L (0.19 μg/kg) for BPA, a NOEC of
-
prosobranch snails as test organisms for the assessment of endocrine active chemicals an overview and a guideline proposal for a reproduction test with the freshwater mudsnail potamopyrgus antipodarum
Ecotoxicology, 2007Co-Authors: Martina Duft, Claudia Schmitt, Cornelius Brandelik, Jean Bachmann, Ulrike Schulteoehlmann, Jörg OehlmannAbstract:Recently, prosobranch snails have been recommended as promising candidates for test organisms for the assessment of endocrine active chemicals. Three prosobranch snail species, the freshwater mudsnail Potamopyrgus antipodarum, the freshwater ramshorn snail Marisa cornuarietis, and the marine netted whelk Nassarius reticulatus are portrayed and their respective biotests are presented together with results of laboratory experiments and biological effect monitoring surveys in the field. All characterized species are highly sensitive toward xeno-androgens [triphenyltin (TPT), tributyltin (TBT), methyltestosterone (MT) and fenarimol (FEN)], and xeno-estrogens [bisphenol A (BPA), octylphenol (OP), ethinylestradiol], and show effects at environmentally relevant, rather low concentrations in laboratory experiments. For exposure to the xeno-androgen TPT, EC10 values range between 15.9 and 29.0 ng as Sn/L (sediment 0.03 μg as Sn/kg), for TBT, EC10 values are found between 3.42 and 37.8 ng as Sn/L (sediment 2.98 μg as Sn/kg) and effect concentrations for FEN are calculated as 18.6 ng/L (EC10) and 0.19 μg/kg (EC50 sediment; EC10 not calculable). Exposure to xeno-estrogens yielded EC10 values of 13.9 ng/L (0.19 μg/kg) for BPA, a NOEC of <1 μg/L (EC10 of 0.004 μg/kg) for OP and a NOEC of 1 ng/l (EC10 sediment of 2.2 μg/kg) for ethinylestradiol. Responses to androgens comprised the development of imposex and the reduction of fertility or embryo production, effects of estrogens included the stimulation of egg production and embryo production, and the increased weight of glands. Also, biological effect monitoring studies with P. antipodarum and N. reticulatus in several rivers or estuarine areas revealed the capacity of the biotests to detect an androgenic or estrogenic potential of sediment samples. A comparison of the three test species with regard to sensitivity and practical aspects in routine application favors the freshwater mudsnail P. antipodarum for a standardized procedure, and this reproduction test will be introduced into the OECD guideline program for standardization in the near future.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental health perspectives, 2006Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 microg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27 degrees C (EC10 998 ng/L) when compared with 20 degrees C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20 degrees C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental Health Perspectives, 2005Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 μg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27°C (EC10 998 ng/L) when compared with 20°C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20°C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
-
Toxicity of triphenyltin and tributyltin to the freshwater mudsnail Potamopyrgus antipodarum in a new sediment biotest.
Environmental Toxicology and Chemistry, 2003Co-Authors: Martina Duft, Ulrike Schulte-oehlmann, Michaela Tillmann, Bernd Markert, Jörg OehlmannAbstract:The effects of two suspected endocrine-disrupting chemicals, the xeno-androgens triphenyltin (TPT) and tributyltin (TBT), were investigated in a new whole-sediment biotest with the freshwater mudsnail Potamopyrgus antipodarum (Gastropoda, Prosobranchia). Artificial sediments were spiked with seven concentrations, ranging from 10 to 500 μg nominal TPT-Sn/kg dry weight and TBT-Sn/kg dry weight, respectively. We analyzed the responses of the test species after two, four, and eight weeks exposure. For both compounds, P. antipodarum exhibited a sharp decline in the number of embryos sheltered in its brood pouch in a time- and concentration-dependent manner in comparison to the control sediment. The number of new, still unshelled embryos turned out to be the most sensitive parameter. The lowest-observed-effect concentration (LOEC) was equivalent to the lowest administered concentration (10 μg/kg of each test compound) for most parameters and thus no no-observed-effect concentration (NOEC) could be established. The calculation of effect concentrations (EC10) resulted in even lower values for both substances (EC10 after eight weeks for unshelled embryos: 0.03 μg TPT-Sn/kg, EC10 after four weeks for unshelled embryos: 0.98 μg TBT-Sn/kg). Our results indicate that P. antipodarum is highly sensitive to both endocrine disruptors TPT and TBT at environmentally relevant concentrations.
Marcos Sotomayor - One of the best experts on this subject based on the ideXlab platform.
-
A Mechanically Weak Extracellular Membrane-Adjacent Domain Induces Dimerization of Protocadherin-15.
Biophysical journal, 2018Co-Authors: Pedro De-la-torre, Deepanshu Choudhary, Yoshie Narui, Raul Araya-secchi, Marcos SotomayorAbstract:Abstract The cadherin superfamily of proteins is defined by the presence of extracellular cadherin (EC) “repeats” that engage in protein-protein interactions to mediate cell-cell adhesion, cell signaling, and mechanotransduction. The extracellular domains of nonclassical cadherins often have a large number of EC repeats along with other subdomains of various folds. Protocadherin-15 (PCDH15), a protein component of the inner-ear tip link filament essential for mechanotransduction, has 11 EC repeats and a membrane adjacent domain (MAD12) of atypical fold. Here we report the crystal structure of a pig PCDH15 fragment including EC10, EC11, and MAD12 in a parallel dimeric arrangement. MAD12 has a unique molecular architecture and folds as a ferredoxin-like domain similar to that found in the nucleoporin protein Nup54. Analytical ultracentrifugation experiments along with size-exclusion chromatography coupled to multiangle laser light scattering and small-angle x-ray scattering corroborate the crystallographic dimer and show that MAD12 induces parallel dimerization of PCDH15 near its membrane insertion point. In addition, steered molecular dynamics simulations suggest that MAD12 is mechanically weak and may unfold before tip-link rupture. Sequence analyses and structural modeling predict the existence of similar domains in cadherin-23, protocadherin-24, and the “giant” FAT and CELSR cadherins, indicating that some of them may also exhibit MAD-induced parallel dimerization.
-
A Mechanically Weak Extracellular Membrane-Adjacent Domain Induces Dimerization of Protocadherin-15
2018Co-Authors: Pedro De-la-torre, Deepanshu Choudhary, Yoshie Narui, Raul Araya-secchi, Marcos SotomayorAbstract:The cadherin superfamily of proteins is defined by the presence of extracellular cadherin (EC) repeats that engage in protein-protein interactions to mediate cell-cell adhesion, cell signaling, and mechanotransduction. The extracellular domains of non-classical cadherins often have a large number of EC repeats along with other subdomains of various folds. Protocadherin-15 (PCDH15), a protein component of the inner-ear tip link filament essential for mechanotransduction, has eleven EC repeats and a membrane adjacent domain (MAD12) of atypical fold. Here we report the crystal structure of a pig PCDH15 fragment including EC10, EC11, and MAD12 in a parallel dimeric arrangement. MAD12 has a unique molecular architecture and folds as a ferredoxin-like domain similar to that found in the nucleoporin protein Nup54. Analytical ultracentrifugation experiments along with size exclusion chromatography coupled to multi-angle laser light scattering and small-angle X-ray scattering corroborate the crystallographic dimer and show that MAD12 induces parallel dimerization of PCDH15 near its membrane insertion point. In addition, steered molecular dynamics simulations suggest that MAD12 is mechanically weak and may unfold before tip-link rupture. Sequence analyses and structural modeling predict the existence of similar domains in cadherin-23, protocadherin-24, and the "giant" FAT and CELSR cadherins, indicating that some of them may also exhibit MAD-induced parallel dimerization.
-
An elastic element in the protocadherin-15 tip link of the inner ear
Nature communications, 2016Co-Authors: Raul Araya-secchi, Brandon L. Neel, Marcos SotomayorAbstract:Tip link filaments convey force and gate inner-ear hair-cell transduction channels to mediate perception of sound and head movements. Cadherin-23 and protocadherin-15 form tip links through a calcium-dependent interaction of their extracellular domains made of multiple extracellular cadherin (EC) repeats. These repeats are structurally similar, but not identical in sequence, often featuring linkers with conserved calcium-binding sites that confer mechanical strength to them. Here we present the X-ray crystal structures of human protocadherin-15 EC8-EC10 and mouse EC9-EC10, which show an EC8-9 canonical-like calcium-binding linker, and an EC9-10 calcium-free linker that alters the linear arrangement of EC repeats. Molecular dynamics simulations and small-angle X-ray scattering experiments support this non-linear conformation. Simulations also suggest that unbending of EC9-10 confers some elasticity to otherwise rigid tip links. The new structure provides a first view of protocadherin-15's non-canonical EC linkers and suggests how they may function in inner-ear mechanotransduction, with implications for other cadherins.
-
Structure and Stability of Tip Link Cadherin-23 Fragments Involved in Hearing and Deafness
Biophysical Journal, 2016Co-Authors: Avinash Jaiganesh, Deryanur Kilic, Aniket Patel, Domenic J. Termine, Florencia Velez-cortes, Ömer İrfan Küfrevioğlu, Marcos SotomayorAbstract:Tip links, core components of vertebrate hearing, are thought to directly pull on mechanotransduction channels to transform sound into electrical signals. Cadherin-23 (cdh23) and protocadherin-15 (pcdh15), the two proteins that form the tip link, belong to the cadherin superfamily of calcium-dependent adhesion molecules that feature extracellular cadherin (EC) repeats. These EC repeats are ∼ 100 residues long and are similar but not identical to each other in terms of fold and sequence. Cdh23 features twenty-seven EC repeats and pcdh15 eleven, with calcium-binding sites located at the linkers between them. Calcium and highly conserved calcium-binding residues are crucial for the elasticity and function of the tip link. These same residues are often mutated in inherited deafness. Here, we present the first crystal structures of cdh23 EC19-21, the least conserved cdh23 fragment among different species, in wild type form and carrying disease-related mutations (R2029W and D2148N). In addition, we use thermal melting and calcium-binding assays to characterize various wild type and mutant cdh23 fragments, including cdh23 EC12-13, EC13-15, EC19-21, and EC21-23. These experiments show how deafness mutations and natural sequence variations throughout the enormous cdh23 extracellular domain affect folding, affinity for calcium, stability, and function. Overall, our structures and biophysical studies provide insight into cdh23 and tip link function in mechanosensation.
Jean Bachmann - One of the best experts on this subject based on the ideXlab platform.
-
Prosobranch snails as test organisms for the assessment of endocrine active chemicals--an overview and a guideline proposal for a reproduction test with the freshwater mudsnail Potamopyrgus antipodarum.
Ecotoxicology, 2007Co-Authors: Martina Duft, Claudia Schmitt, Cornelius Brandelik, Ulrike Schulte-oehlmann, Jean Bachmann, Jörg OehlmannAbstract:Recently, prosobranch snails have been recommended as promising candidates for test organisms for the assessment of endocrine active chemicals. Three prosobranch snail species, the freshwater mudsnail Potamopyrgus antipodarum, the freshwater ramshorn snail Marisa cornuarietis, and the marine netted whelk Nassarius reticulatus are portrayed and their respective biotests are presented together with results of laboratory experiments and biological effect monitoring surveys in the field. All characterized species are highly sensitive toward xeno-androgens [triphenyltin (TPT), tributyltin (TBT), methyltestosterone (MT) and fenarimol (FEN)], and xeno-estrogens [bisphenol A (BPA), octylphenol (OP), ethinylestradiol], and show effects at environmentally relevant, rather low concentrations in laboratory experiments. For exposure to the xeno-androgen TPT, EC10 values range between 15.9 and 29.0 ng as Sn/L (sediment 0.03 μg as Sn/kg), for TBT, EC10 values are found between 3.42 and 37.8 ng as Sn/L (sediment 2.98 μg as Sn/kg) and effect concentrations for FEN are calculated as 18.6 ng/L (EC10) and 0.19 μg/kg (EC50 sediment; EC10 not calculable). Exposure to xeno-estrogens yielded EC10 values of 13.9 ng/L (0.19 μg/kg) for BPA, a NOEC of
-
prosobranch snails as test organisms for the assessment of endocrine active chemicals an overview and a guideline proposal for a reproduction test with the freshwater mudsnail potamopyrgus antipodarum
Ecotoxicology, 2007Co-Authors: Martina Duft, Claudia Schmitt, Cornelius Brandelik, Jean Bachmann, Ulrike Schulteoehlmann, Jörg OehlmannAbstract:Recently, prosobranch snails have been recommended as promising candidates for test organisms for the assessment of endocrine active chemicals. Three prosobranch snail species, the freshwater mudsnail Potamopyrgus antipodarum, the freshwater ramshorn snail Marisa cornuarietis, and the marine netted whelk Nassarius reticulatus are portrayed and their respective biotests are presented together with results of laboratory experiments and biological effect monitoring surveys in the field. All characterized species are highly sensitive toward xeno-androgens [triphenyltin (TPT), tributyltin (TBT), methyltestosterone (MT) and fenarimol (FEN)], and xeno-estrogens [bisphenol A (BPA), octylphenol (OP), ethinylestradiol], and show effects at environmentally relevant, rather low concentrations in laboratory experiments. For exposure to the xeno-androgen TPT, EC10 values range between 15.9 and 29.0 ng as Sn/L (sediment 0.03 μg as Sn/kg), for TBT, EC10 values are found between 3.42 and 37.8 ng as Sn/L (sediment 2.98 μg as Sn/kg) and effect concentrations for FEN are calculated as 18.6 ng/L (EC10) and 0.19 μg/kg (EC50 sediment; EC10 not calculable). Exposure to xeno-estrogens yielded EC10 values of 13.9 ng/L (0.19 μg/kg) for BPA, a NOEC of <1 μg/L (EC10 of 0.004 μg/kg) for OP and a NOEC of 1 ng/l (EC10 sediment of 2.2 μg/kg) for ethinylestradiol. Responses to androgens comprised the development of imposex and the reduction of fertility or embryo production, effects of estrogens included the stimulation of egg production and embryo production, and the increased weight of glands. Also, biological effect monitoring studies with P. antipodarum and N. reticulatus in several rivers or estuarine areas revealed the capacity of the biotests to detect an androgenic or estrogenic potential of sediment samples. A comparison of the three test species with regard to sensitivity and practical aspects in routine application favors the freshwater mudsnail P. antipodarum for a standardized procedure, and this reproduction test will be introduced into the OECD guideline program for standardization in the near future.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental health perspectives, 2006Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 microg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27 degrees C (EC10 998 ng/L) when compared with 20 degrees C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20 degrees C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental Health Perspectives, 2005Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 μg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27°C (EC10 998 ng/L) when compared with 20°C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20°C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
Thomas A Ternes - One of the best experts on this subject based on the ideXlab platform.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental health perspectives, 2006Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 microg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27 degrees C (EC10 998 ng/L) when compared with 20 degrees C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20 degrees C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental Health Perspectives, 2005Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 μg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27°C (EC10 998 ng/L) when compared with 20°C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20°C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
Ulrike Schulte-oehlmann - One of the best experts on this subject based on the ideXlab platform.
-
Prosobranch snails as test organisms for the assessment of endocrine active chemicals--an overview and a guideline proposal for a reproduction test with the freshwater mudsnail Potamopyrgus antipodarum.
Ecotoxicology, 2007Co-Authors: Martina Duft, Claudia Schmitt, Cornelius Brandelik, Ulrike Schulte-oehlmann, Jean Bachmann, Jörg OehlmannAbstract:Recently, prosobranch snails have been recommended as promising candidates for test organisms for the assessment of endocrine active chemicals. Three prosobranch snail species, the freshwater mudsnail Potamopyrgus antipodarum, the freshwater ramshorn snail Marisa cornuarietis, and the marine netted whelk Nassarius reticulatus are portrayed and their respective biotests are presented together with results of laboratory experiments and biological effect monitoring surveys in the field. All characterized species are highly sensitive toward xeno-androgens [triphenyltin (TPT), tributyltin (TBT), methyltestosterone (MT) and fenarimol (FEN)], and xeno-estrogens [bisphenol A (BPA), octylphenol (OP), ethinylestradiol], and show effects at environmentally relevant, rather low concentrations in laboratory experiments. For exposure to the xeno-androgen TPT, EC10 values range between 15.9 and 29.0 ng as Sn/L (sediment 0.03 μg as Sn/kg), for TBT, EC10 values are found between 3.42 and 37.8 ng as Sn/L (sediment 2.98 μg as Sn/kg) and effect concentrations for FEN are calculated as 18.6 ng/L (EC10) and 0.19 μg/kg (EC50 sediment; EC10 not calculable). Exposure to xeno-estrogens yielded EC10 values of 13.9 ng/L (0.19 μg/kg) for BPA, a NOEC of
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental health perspectives, 2006Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 microg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27 degrees C (EC10 998 ng/L) when compared with 20 degrees C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20 degrees C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
-
Bisphenol A induces superfeminization in the ramshorn snail Marisa cornuarietis(Gastropoda: Prosobranchia) at environmentally relevant concentrations.
Environmental Health Perspectives, 2005Co-Authors: Jörg Oehlmann, Ulrike Schulte-oehlmann, Jean Bachmann, Matthias Oetken, Ilka Lutz, Werner Kloas, Thomas A TernesAbstract:Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 μg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27°C (EC10 998 ng/L) when compared with 20°C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20°C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions.
-
Toxicity of triphenyltin and tributyltin to the freshwater mudsnail Potamopyrgus antipodarum in a new sediment biotest.
Environmental Toxicology and Chemistry, 2003Co-Authors: Martina Duft, Ulrike Schulte-oehlmann, Michaela Tillmann, Bernd Markert, Jörg OehlmannAbstract:The effects of two suspected endocrine-disrupting chemicals, the xeno-androgens triphenyltin (TPT) and tributyltin (TBT), were investigated in a new whole-sediment biotest with the freshwater mudsnail Potamopyrgus antipodarum (Gastropoda, Prosobranchia). Artificial sediments were spiked with seven concentrations, ranging from 10 to 500 μg nominal TPT-Sn/kg dry weight and TBT-Sn/kg dry weight, respectively. We analyzed the responses of the test species after two, four, and eight weeks exposure. For both compounds, P. antipodarum exhibited a sharp decline in the number of embryos sheltered in its brood pouch in a time- and concentration-dependent manner in comparison to the control sediment. The number of new, still unshelled embryos turned out to be the most sensitive parameter. The lowest-observed-effect concentration (LOEC) was equivalent to the lowest administered concentration (10 μg/kg of each test compound) for most parameters and thus no no-observed-effect concentration (NOEC) could be established. The calculation of effect concentrations (EC10) resulted in even lower values for both substances (EC10 after eight weeks for unshelled embryos: 0.03 μg TPT-Sn/kg, EC10 after four weeks for unshelled embryos: 0.98 μg TBT-Sn/kg). Our results indicate that P. antipodarum is highly sensitive to both endocrine disruptors TPT and TBT at environmentally relevant concentrations.