Environmental endocrine disrupters dysregulate estrogen metabolism and Ca2+ homeostasis in fish and mammals via receptor-independent mechanisms

Estrogen Receptors Mediated Negative Effects of Estrogens and Xenoestrogens in Teleost Fishes-Review

Estrogen receptors (ERs) play a key role in many biochemical and physiological processes, that are involved in maintaining organism homeostasis. At the most basic level, they can be divided into nuclear estrogen receptors and membrane estrogen receptors that imply their effect in two ways: slower genomic, and faster non-genomic. In these ways, estrogens and xenoestrogens can negatively affect animal health and welfare. Most of the available literature focuses on human and mammalian physiology, and clearly, we can observe a need for further research focusing on complex mutual interactions between different estrogens and xenoestrogens in aquatic animals, primarily fishes. Understanding the mechanisms of action of estrogenic compounds on the ERs in fishes and their negative consequences, may improve efforts in environmental protection of these animals and their environment and benefit society in return. In this review, we have summarized the ER-mediated effects of xenoestrogens and estrogens on teleost fishes metabolism, their carcinogenic potential, immune, circulatory, and reproductive systems.

Nacre extract from pearl oyster attenuates amyloid beta-induced memory impairment

Shells are composed of two types of calcium carbonate polymorphs-the prismatic layer and the nacreous layer. Pearls, composed of the nacreous layer, have been used in Chinese medicine since ancient times. We have previously shown that extracts from the nacreous layer improves scopolamine-induced memory impairment. However, whether pearl ameliorates cognitive disorders induced by amyloid-β 1-40 (Aβ1-40) has not been elucidated. In this study, we investigated whether nacre extract improves memory impairment induced by intracerebroventricular injection of Aβ1-40. Administration of nacre extract led to recovery from Aβ1-40-induced impairments in object recognition, short-term memory, and spatial memory. Nacre extract reversed the increase in lipid peroxidation caused by Aβ1-40 in the cerebral cortex by increasing the expression of catalase and superoxide dismutase. In addition, nacre extract recovered the expression and phosphorylation of cyclic AMP response element-binding protein (CREB), which decreased with Aβ1-40 treatment, and increased the expression of brain-derived neurotrophic factor and neuropeptide Y, which are regulated by CREB. Nacre extract also suppressed acetylcholine esterase activity and Aβ1-40-induced tau phosphorylation. Histochemical analysis of the hippocampus region showed that the nacre extract protected against Aβ1-40-induced neuronal loss in the hippocampus. These results suggest that nacre extract protects against Aβ1-40-induced neuronal cell death by suppressing oxidative stress and increasing the expression and phosphorylation of CREB.

Physiological Effects and Transcriptomic Analysis of sbGnRH on the Liver in Pompano (Trachinotus ovatus)

Pompano (Trachinotus ovatus) is one of the important economic marine fishes in the south coast of China. At present, the research on the basic biology of pompano is relatively weak, which has seriously affected the development of this economic important fish. The liver is an important digestive and metabolic organ of fish which plays an important regulatory role in its growth and development. It is necessary to clarify the effects of sea bream gonadotropin releasing hormone (sbGnRH) on liver physiology and metabolic enzyme activity. The effects of sbGnRH peptides (10 ng/gbw) on the physiological and biochemical indices and metabolic enzyme activities of pompano liver were studied. It was found that after injection of 10 ng/gbw sbGnRH peptides, the contents of albumin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, glucose, creatine kinase, iron, magnesium, aspartate aminotransferase, alanine aminotransferase and creatinine increased, while of cholesterol and calcium contents decreased. The activities of amylase, lipase, pyruvate kinase, acyl CoA oxidase, superoxide dismutase, phospholipid hydroperoxide glutathione peroxidase, catalase, glucose-6-phosphate dehydrogenase, fatty acid synthase and lipoprotein lipase increased, while the activities of malic enzyme, carnitine acyl, carnitine translocation, acetyl CoA carboxylase and malondialdehyde decreased. Three hours after the injection of different concentrations of sbGnRH peptides (0 and 10 ng/gbw), the transcriptome sequences of the two groups of livers were sequenced. After quality control and removal of some low-quality data, clean reads of 21,283,647、19,427,359、21,873,990、21,732,174、23,660,062 and 21,592,338 were obtained respectively. In this study, 99 genes were screened and identified as differentially expressed genes, including 77 up-regulated genes and 22 down-regulated genes. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway analyses, these pathways and the typical genes involved can be divided into cellular processes, environmental information processing, genetic information processing, diseases, metabolism and organismal systems. The results from this study provide a the oretical basis for studying the effects of sbGnRH on the physiology, biochemistry and metabolic enzyme activities of liver in pompano.

Transcriptomic analysis of pituitary in female and male spotted scat (Scatophagus argus) after 17β-estradiol injection

Spotted scat (Scatophagus argus) is a popular species of marine fish cultured in China. It shows normal sexual growth dimorphism. Female spotted scat grows quicker and bigger than males. Growth and reproduction are the most important traits in aquaculture. In vertebrates, the pituitary gland occupies an important position in the growth and reproduction axis. Estrogen is involved in regulating growth and reproduction in the pituitary gland in an endocrine fashion. Transcriptome sequencing of the pituitary was performed in female and male fish at 6 h after 17β-estradiol injection (4.0 μg E₂/g body weight, BW). Compared with the pituitary of female and male groups, 144 and 64 genes [|log₂^{(fold change)}| ≥ 1.0 and false discovery rate (FDR) < 0.05] were significantly differentially expressed in E₂-injected females and males, respectively (p < 0.05). Of these, 59 and 48 were up-regulated, and 85 and 16 were down-regulated. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) pathway analyses, DEGs were involved in signal pathways, such as growth, reproduction, oocyte meiosis and steroid biosynthesis. Of these, estrogen affected the expression of some sex steroid synthesis and receptor genes in the pituitary gland through feedback, such as hsd17b7, pgr and cyp19a1b, regulating the reproductive activities. Besides, some growth-related genes, such as gap43, junbb, mstn2 and insm1a responded to estrogen. E₂ might affect the expression level of gh mRNA by regulating the expression levels of growth-related genes. Our results provide a theoretical basis for studying the molecular mechanism of growth and reproduction regulation at the pituitary level of spotted scat responded to E₂.

Extraction and characterization of matrix protein from pacific oyster (Crassostrea gigs) shell and its anti-osteoporosis properties in vitro and in vivo

Matrix protein is a kind of secretory protein that regulates the biomineralization of the bivalve shell. In this study, a water-soluble matrix protein (WSMP) from Pacific oysters (Crassostrea gigs) shell was isolated, and its structure was analyzed in detail, in addition to its anti-osteoporosis activity in vitro and in vivo. Results showed that WSMP was an acidic protein with an apparent molecular mass of 47 and 79 kDa and contained a glycoprotein structure. In vitro, the reduction of Tartrate-resistant acid phosphatase (TRAP) and deoxypyridinoline (DPD) indicated that osteoclast activity was inhibited compared with the model group. Moreover, the increased osteocalcin (OCN) and BMD levels suggested that the high osteoblast activity and bone mineralization was improved. SEM analysis of the femur showed that there were fewer bone pits in experimental groups, which was consistent with the above results. In vivo, WSMP promoted the expression of alkaline phosphatase (ALP) and osteogenic differentiation factor BMP-2 in osteoblasts. In addition, the activity of osteoclasts was inhibited by regulating the process of osteoclast differentiation induced by RANKL. Both in vitro and in vivo studies showed that WSMP could promote osteogenesis and inhibit osteoclast absorption, thus demonstrating their potential applications in osteoporosis.

Global expression response of genes in sex-undifferentiated Nile tilapia gonads after exposure to trace letrozole

The aromatase inhibitor letrozole can be found in rivers, effluents, and even drinking water. Studies have demonstrated that letrozole affects various metabolic pathways and may cause reproductive toxicity, especially in fish exposed during development. However, studies on the effect of a low concentration of letrozole at the whole-gonad transcriptomic level in the early stage of fish sexual development have not been investigated. The aim of our study was to explore the potential effects of a low concentration of letrozole on the gonad transcriptome of Nile tilapia at an early stage of sexual development. In this study, 9 dpf (days postfertilization) Nile tilapia were exposed to trace letrozole for 12 days. Letrozole exposure from 9 dpf to 21 dpf persistently altered phenotypic sex development and induced the male-biased sex ratio. The transcriptome results showed that 1173 differentially expressed genes (DEGs) were present in the female control vs 1.5 μg/L letrozole-treated female comparison group and that 1576 DEGs were present in the 1.5 μg/L letrozole-treated female vs male control comparison group. Differentially expressed gene enrichment analysis revealed several crucial pathways, including the drug metabolism-cytochrome P450 pathway, the ErbB-PI3K/Akt/mTOR pathway, and the calcium signalling pathway. Further analysis of these identified DEGs indicated that some key genes correlated with metabolism and epigenetic regulation were significantly affected by letrozole, such as UDP-glucuronosyltransferase (Ugt), glutathione S-transferase omega-1 (Gsto1), lysine-specific demethylase 6bb (Kdm6bb, original name is Kdm6a), jumonji and AT-rich interaction domain containing 2 (Jarid2b, original name is Jarid2), growth arrest and DNA damage inducible gamma (Gadd45g), and chromobox protein 7 (Cbx7). The qRT-PCR validation results for twelve DEGs showed that the Pearson's correlation of the log₁₀^{fold change} values between the qPCR and RNA-Seq results was 0.90, indicating the accuracy and reliability of the RNA-Seq results. Our study is the first to report the effect of letrozole on the transcriptome of gonads from fish during early-stage sexual development. These findings will be useful for understanding the toxic effects and molecular mechanisms of letrozole exposure at the early stage of gonad development on the sexual development of aquatic organisms.

Specifiable biomimetic microsponges for timed release of crystal entrapped biomolecules useful in bone repair

Most marine materials, by nature, contain crystals of inorganic matter with specific structures that allow the loading, release, and delivery of biomolecules that can be utilized in clinical applications. These structures can be biomimetically synthesized. Aggregates of inorganic particles generated by biomimetic microsponges may provide surfaces and structures for cell attachment, organization, and promotion of matrix synthesis. Biomimetic microsponges have been developed with tunable release profiles differing by the rate (speed over distance), velocity (rate of change in direction), and the quantity discharged over time, according to biomolecular species. Specifically, the types of proteins involved guide and regulate cells in physical contact with the microsponges, for instance, reprogramming somatic cells, the switching phenotypes, or specifying stem cell differentiation. Applications for these microsponges include gene transfection of localized cells and promotion of bone matrix synthesis by the externalized display of RGD cell adhesive peptides and the release of crystal entrapped, occluded, adsorbed and infused rhBMP-2 and plasmid. A requirement for de novo bone formation is a solid structure to enable osteocytes to lay new bone tissue. In this study, biomimetic microsponges highlight tremendous potential as osteoconductive packing material in bone repair with parallel influence on regeneration. Majorly, microsponges offer pronounced osteoinductivity, unlike many other bone particulates, by solid-state integration of active regenerative biological molecules through the prism of the biomineral crystalline structure.

Micropatterning biomineralization with immobilized mother of pearl proteins

In response to the drawbacks of autograft donor-site morbidity and bone morphogenetic protein type 2 (BMP2) carcinogenesis and ectopic bone formation, there has been an increased research focus towards developing alternatives capable of achieving spatial control over bone formation. Here we show for the first time both osteogenic differentiation and mineralization (from solution or mediated by cells) occurring within predetermined microscopic patterns. Our results revealed that both PEGylated BMP2 and nacre proteins induced stem cell osteodifferentiation in microscopic patterns when these proteins were covalently bonded in patterns onto polyethylene glycol diacrylate (PEGDA) hydrogel substrates; however, only nacre proteins induced mineralization localized to the micropatterns. These findings have broad implications on the design and development of orthopedic biomaterials and drug delivery.

The role of epigenetics in the reproductive toxicity of environmental endocrine disruptors

Environmental endocrine disruptors (EEDs) seriously endanger human health by interfering with the normal function of reproductive systems. In males, EEDs can affect sperm formation and semen quality as well spermatogenesis, ultimately reducing fertility. In females, EEDs can affect uterine development and the expression levels of reproduction-related genes, ultimately reducing female fertility and the normal development of the fetus. There are a large number of putative mechanisms by which EEDs can induce reproductive toxicity, and many studies have shown the involvement of epigenetics. In this review, we summarize the role of DNA methylation, noncoding RNAs, genomic imprinting, chromatin remodeling and histone modification in the reproductive toxicity of EEDs.

Association of fine-particulate and acidic-gas air pollution with premenstrual syndrome risk

OBJECTIVE

Air pollution had been reported to be associated with the reproductive health of women. However, the association of particulate matter (PM) and acid gases air pollution with premenstrual syndrome (PMS) warrants investigation. This study investigated the effects of air pollution on PMS risk.

POPULATION

We combined data from the Taiwan Air Quality-Monitoring Database and the Longitudinal Health Insurance Database. In total, an observational cohort of 85 078 Taiwanese women not diagnosed as having PMS.

METHODS

Air pollutant concentrations were grouped into four levels based on the concentration quartiles of several types of air pollutants.

MAIN OUTCOME MEASURES

We then applied univariable and multivariable Cox proportional hazard regression models to assess PMS risk in association with each pollutant type.

RESULTS

Women exposed to Q4-level SO2 exhibited a 7.77 times higher PMS risk compared with those to Q1-level SO2 (95% confidence interval [CI] = 6.22-9.71). Women exposed to Q4-level NOx exhibited a 2.86 times higher PMS risk compared with those exposed to Q1-level NOx (95% CI = 2.39-3.43). Women exposed to Q4-level NO exhibited a 3.17 times higher PMS risk compared with women exposed to Q1-level NO (95% CI = 2.68-3.75). Finally, women exposed to Q4-level PM with a ≤2.5-µm diameter (PM2.5) exhibited a 3.41 times higher PMS risk compared with those exposed to Q1-level PM2.5 (95% CI = 2.88-4.04).

CONCLUSIONS

High incidences of PMS were noted in women who lived in areas with higher concentrations of SO2, NOx, NO, NO2 and PM2.5.

Sarco/Endoplasmic Reticulum Calcium ATPase Inhibitors: Beyond Anticancer Perspective

The sarco/endoplasmic reticulum calcium ATPase (SERCA), which plays a key role in the maintenance of Ca²⁺ ion homeostasis, is an extensively studied enzyme, the inhibition of which has a considerable impact on cell life and death decision. To date, several SERCA inhibitors have been thoroughly studied and the most notable one, a derivative of the sesquiterpene lactone thapsigargin, is gradually approaching a clinical application. Meanwhile, new compounds with SERCA-inhibiting properties of natural, synthetic, or semisynthetic origin are being discovered and/or developed; some of these might also be suitable for the development of new drugs with improved performance. This review brings an up-to-date comprehensive overview of recently discovered compounds with the potential of SERCA inhibition, discusses their mechanism of action, and highlights their potential clinical applications, such as cancer treatment.

Toxicity of nonylphenol and nonylphenol ethoxylate on Caenorhabditis elegans

Among the most used chemicals in the world are nonionic surfactants. One of these environmental pollutants is nonylphenol ethoxylate (NP-9), also known as Tergitol, and its degradation product, nonylphenol (NP). The objective of this work was to determine the toxicity of NP and NP-9 in Caenorhabditis elegans. Wild-type L4 larvae were exposed to different concentrations of the surfactants to measure functional endpoints. Mutant strains were employed to promote the activation of toxicity signaling pathways related to mtl-2, gst-1, gpx-4, gpx-6, sod-4, hsp-70 and hsp-4. Additionally, stress response was also assessed using a daf-16::GFP transgenic strain. The lethality was concentration dependent, with 24-h LC₅₀ of 122 μM and 3215 μM for NP and NP-9, respectively. Both compounds inhibited nematode growth, although NP was more potent; and at non-lethal concentrations, nematode locomotion was reduced. The increase in the expression of tested genes was significant at 10 μM for NP-9 and 0.001 μM for NP, implying a likely role for the activation of oxidative and cellular stress, as well as metabolism pathways. With the exception of glutathione peroxidase, which has a bimodal concentration-response curve for NP, typical of endocrine disruption, the other curves for this xenobiotic in the strains evaluated were almost flat for most concentrations, until reaching 50-100 μM, where the effect peaked. NP and NP-9 induced the activation and nuclear translocation of DAF-16, suggesting that transcription of stress-response genes may be mediated by the insulin/IGF-1 signaling pathway. In contrast, NP-9 induced a concentration-dependent response for the sod-4 and hsp-4 mutants, with greater fluorescence induction than NP at similar levels. In short, NP and NP-9 affect the physiology of C. elegans and modulate gene expression related to ROS production, cellular stress and metabolism of xenobiotics.

Diet as a Source of Exposure to Environmental Contaminants for Pregnant Women and Children from Six European Countries

BACKGROUND

Pregnant women and children are especially vulnerable to exposures to food contaminants, and a balanced diet during these periods is critical for optimal nutritional status.

OBJECTIVES

Our objective was to study the association between diet and measured blood and urinary levels of environmental contaminants in mother-child pairs from six European birth cohorts (n = 818 mothers and 1,288 children).

METHODS

We assessed the consumption of seven food groups and the blood levels of organochlorine pesticides, polybrominated diphenyl ethers, polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFAS), and heavy metals and urinary levels of phthalate metabolites, phenolic compounds, and organophosphate pesticide (OP) metabolites. Organic food consumption during childhood was also studied. We applied multivariable linear regressions and targeted maximum likelihood based estimation (TMLE).

RESULTS

Maternal high (≥ 4   times / week ) versus low (< 2   times / week ) fish consumption was associated with 15% higher PCBs [geometric mean (GM) ratio = 1.15 ; 95% confidence interval (CI): 1.02, 1.29], 42% higher perfluoroundecanoate (PFUnDA) (GM   ratio = 1.42 ; 95% CI: 1.20, 1.68), 89% higher mercury (Hg) (GM   ratio = 1.89 ; 95% CI: 1.47, 2.41) and a 487% increase in arsenic (As) (GM   ratio = 4.87 ; 95% CI: 2.57, 9.23) levels. In children, high (≥ 3   times / week ) versus low (< 1.5   times / week ) fish consumption was associated with 23% higher perfluorononanoate (PFNA) (GM   ratio = 1.23 ; 95% CI: 1.08, 1.40), 36% higher PFUnDA (GM   ratio = 1.36 ; 95% CI: 1.12, 1.64), 37% higher perfluorooctane sulfonate (PFOS) (GM   ratio = 1.37 ; 95% CI: 1.22, 1.54), and > 200 % higher Hg and As [GM   ratio = 3.87 (95% CI: 1.91, 4.31) and GM   ratio = 2.68 (95% CI: 2.23, 3.21)] concentrations. Using TMLE analysis, we estimated that fish consumption within the recommended 2-3 times/week resulted in lower PFAS, Hg, and As compared with higher consumption. Fruit consumption was positively associated with OP metabolites. Organic food consumption was negatively associated with OP metabolites.

DISCUSSION

Fish consumption is related to higher PFAS, Hg, and As exposures. In addition, fruit consumption is a source of exposure to OPs. https://doi.org/10.1289/EHP5324.

Progesterone Antagonizes Dexamethasone-Regulated Surfactant Proteins In Vitro

Pregnant women at risk of preterm labor routinely receive glucocorticoids (GCs) and frequently also progesterone. Administration of GCs accelerates intrauterine surfactant synthesis and lung maturation, thereby reducing the incidence of neonatal respiratory distress syndrome; progesterone has the potential to prevent preterm birth. Little is known about possible interactions of GCs and progesterone. Our aim was to clarify whether progesterone can affect dexamethasone (DXM)-regulated expression of surfactant protein A (SP-A), SP-B, and SP-D in lung epithelial cells. H441 cells were exposed to DXM and progesterone and expression of SPs was analyzed by quantitative real-time polymerase chain reaction and immunoblotting. Although progesterone had no direct effect on the expression of SP-B, DXM-mediated induction was inhibited dose dependently on the transcriptional (64 µM [P < .0001], 32 µM [P = .0005], 16 µM [P = .0019]) and the translational level. Furthermore, progesterone inhibited stimulatory effects of other GCs as well. While exogenous tissue growth factor β1 (TGF-β1) inhibited DXM-induced SP-B expression (messenger RNA [mRNA]: P = .0014), progesterone itself did not influence TGF-β1 mRNA expression and/or TGF-β1/Smad signaling, demonstrating that TGF-β1 and/or Smad activation is not involved. The inhibitory effect of progesterone could be imitated by the GC and progesterone receptor (PR) antagonist RU-486, but not by the specific PR antagonist PF-02413873, indicating that progesterone acts as a competitive antagonist of DXM. The effect of progesterone on DXM-regulated genes was not specific for SP-B, as expression of SP-A and SP-D mRNAs was also antagonized. The present study highlights a new action of progesterone as a potential physiological inhibitor of GC-dependent SP expression in lung epithelial cells. The clinical relevance of this in vitro finding is currently unknown.

Shell extracts of the edible mussel and oyster induce an enhancement of the catabolic pathway of human skin fibroblasts, in vitro

Mollusc shells are composed of more than 95% calcium carbonate and less than 5% organic matrix consisting mostly of proteins, glycoproteins and polysaccharides. In this study, we investigated the effects of matrix macromolecular components extracted from the shells of two edible molluscs of economic interest, i.e., the blue mussel Mytilus edulis and the Pacific oyster Crassostrea gigas. The potential biological activities of these organic molecules were analysed on human dermal fibroblasts in primary culture. Our results demonstrate that shell extracts of the two studied molluscs modulate the metabolic activities of the cells. In addition, the extracts caused a decrease of type I collagen and a concomitant increase of active MMP-1, both at the mRNA and the protein levels. Therefore, our results suggest that shell extracts from M. edulis and C. gigas contain molecules that promote the catabolic pathway of human dermal fibroblasts. This work emphasises the potential use of these shell matrices in the context of anti-fibrotic strategies, particularly against scleroderma. More generally, it stresses the usefulness to valorise bivalve shells that are coproducts of shellfish farming activity.

Preparation and characterization of alginate/HACC/oyster shell powder biocomposite scaffolds for potential bone tissue engineering applications

Tissue engineering scaffolds combining biominerals and natural polymers are prospective candidates for bone repair materials.

Perchlorate disrupts embryonic androgen synthesis and reproductive development in threespine stickleback without changing whole-body levels of thyroid hormone

Perchlorate, an environmental contaminant, disrupts normal functioning of the thyroid. We previously showed that perchlorate disrupts behavior and gonad development, and induces external morphological changes in a vertebrate model organism, the threespine stickleback. Whether perchlorate alters these phenotypes via a thyroid-mediated mechanism, and the extent to which the effects depend on dose, are unknown. To address these questions, we chronically exposed stickleback to control conditions and to three concentrations of perchlorate (10, 30 and 100ppm) at various developmental stages from fertilization to reproductive maturity. Adults chronically exposed to perchlorate had increased numbers of thyroid follicles and decreased numbers of thyrocytes. Surprisingly, T4 and T3 levels in larval, juvenile, and adult whole fish chronically exposed to perchlorate did not differ from controls, except at the lowest perchlorate dose, suggesting a non-monotonic dose response curve. We found no detectable abnormalities in external phenotype at any dose of perchlorate, indicating that the increased number of thyroid follicles compensated for the disruptive effects of these doses. In contrast to external morphology, gonadal development was altered substantially, with the highest dose of perchlorate causing the largest effects. Perchlorate increased the number both of early stage ovarian follicles in females and of advanced spermatogenic stages in males. Perchlorate also disrupted embryonic androgen levels. We conclude that chronic perchlorate exposure may not result in lasting adult gross morphological changes but can produce lasting modifications to gonads when compensation of T3 and T4 levels occurs by thyroid follicle hyperplasia. Perchlorate may therefore affect vertebrate development via both thyroidal and non-thyroidal mechanisms.

Molecular characterization of the BMP7 gene and its potential role in shell formation in Pinctada martensii

Bone morphogenetic protein 7 (BMP7), also called osteogenetic protein-1, can induce bone formation. In this study, the obtained full-length cDNA of BMP7 from Pinctada martensii (Pm-BMP7) was 2972 bp, including a 5'-untranslated region (UTR) of 294 bp, an open reading fragment of 1290 bp encoding a 429 amino acid polypeptide and a 3'-UTR of 1388 bp. The deduced protein sequence of Pm-BMP7 contained a signal peptide, a pro-domain and a mature peptide. The mature peptide consisted of 135 amino acids and included a transforming growth factor β family domain with six shared cysteine residues. The protein sequence of Pm-BMP7 showed 66% identity with that from Crassostrea gigas. Two unigenes encoding Pm-BMPRI (Pm-BMP receptor I) and Pm-BMPRII were obtained from the transcriptome database of P. martensii. Tissue expression analysis demonstrated Pm-BMP7 and Pm-BMPRI were highly expressed in the mantle (shell formation related-tissue), while Pm-BMPRII was highly expressed in the foot. After inhibiting Pm-BMP7 expression using RNA interference (RNAi) technology, Pm-BMP7 mRNA was significantly down-regulated (p < 0.05) in the mantle pallium (nacre formation related-tissue) and the mantle edge (prismatic layer formation related-tissue). The microstructure, observed using a scanning electron microscope, indicated a disordered growth status in the nacre and obvious holes in the prismatic layer in the dsRNA-Pm-BMP7 injected-group. These results suggest that Pm-BMP7 plays a crucial role in the nacre and prismatic layer formation process of the shell.

Developmental toxicity and risk assessment of nonylphenol to the South American toad, Rhinella arenarum

The toxicity of Nonylphenol, an emerging pollutant, on the common South American toad Rhinella arenarum was stage and time dependent, thus Median Lethal Concentrations (LC50) for acute (96h), short-term chronic (168h) and chronic exposure (336h) were 1.06; 0.96 and 0.17mgNP/L from embryonic period (S.4), whereas for exposure from larvae (S.25), LC50 remained constant at 0.37mgNP/L from 96h to 168h, decreasing to 0.11mgNP/L at 336h. NOEC-168h for exposure from embryos was 0.025mgNP/L. The Teratogenic Potential (NOEC-lethality/NOEC-sublethal effects) was 23 times higher than the threshold value, indicating a high risk for embryos to be malformed in absence of significant lethality and representing a threat for the species conservation. By comparing with other amphibians, the early development of R. arenarum was very sensitive to NP. The results highlight the relevance of extending the exposure time and look for the most sensitive stage in order to perform the bioassays for conservation purposes.

Engineering scaffolds integrated with calcium sulfate and oyster shell for enhanced bone tissue regeneration

Engineering scaffolds combinging natural biomineral and artificially synthesized material hold promising potential for bone tissue regeneration. In this study, novel bioactive calcium sulfate/oyster shell (CS/OS) composites were prepared. Comparing to CS scaffold, the CS/OS composites with a controllable degradation rate displayed enhanced mineral nodule formation, higher alkaline phosphate (ALP) activity and increased proliferation rate while treated osteocytes. In CS/OS composites group, elevated mRNA levels of key osteogenic genes including bone morphogenetic protein-2 (BMP-2), runt-related transcription factor 2 (Runx2), osterix (Osx), and osteocalcin (OCN) were observed. Furthermore, The up-regulation of BMP-2 and type I collagen (COL-I) was observed for CS/OS composites relative to a CS group. Scaffolds were implanted into critical-sized femur cavity defects in rabbits to investigate the osteogenic capacity of the composites in vivo. The CS/OS scaffolds with proper suitable times and mechanical strength strongly promoted osteogenic tissue regeneration relative to the regeneration capacity of CS scaffolds, as indicated by the results of histological staining. These results suggest that the OS-modified CS engineering scaffolds with improved mechanical properties and bioactivity would facilitate the development of a new strategy for clinic bone defect regeneration.

High-throughput sequencing and pathway analysis reveal alteration of the pituitary transcriptome by 17α-ethynylestradiol (EE2) in female coho salmon, Oncorhynchus kisutch

Considerable research has been done on the effects of endocrine disrupting chemicals (EDCs) on reproduction and gene expression in the brain, liver and gonads of teleost fish, but information on impacts to the pituitary gland are still limited despite its central role in regulating reproduction. The aim of this study was to further our understanding of the potential effects of natural and synthetic estrogens on the brain-pituitary-gonad axis in fish by determining the effects of 17α-ethynylestradiol (EE2) on the pituitary transcriptome. We exposed sub-adult coho salmon (Oncorhynchus kisutch) to 0 or 12 ng EE2/L for up to 6 weeks and effects on the pituitary transcriptome of females were assessed using high-throughput Illumina(®) sequencing, RNA-Seq and pathway analysis. After 1 or 6 weeks, 218 and 670 contiguous sequences (contigs) respectively, were differentially expressed in pituitaries of EE2-exposed fish relative to control. Two of the most highly up- and down-regulated contigs were luteinizing hormone β subunit (241-fold and 395-fold at 1 and 6 weeks, respectively) and follicle-stimulating hormone β subunit (-3.4-fold at 6 weeks). Additional contigs related to gonadotropin synthesis and release were differentially expressed in EE2-exposed fish relative to controls. These included contigs involved in gonadotropin releasing hormone (GNRH) and transforming growth factor-β signaling. There was an over-representation of significantly affected contigs in 33 and 18 canonical pathways at 1 and 6 weeks, respectively, including circadian rhythm signaling, calcium signaling, peroxisome proliferator-activated receptor (PPAR) signaling, PPARα/retinoid x receptor α activation, and netrin signaling. Network analysis identified potential interactions between genes involved in circadian rhythm and GNRH signaling, suggesting possible effects of EE2 on timing of reproductive events.

Occurrence of selected estrogens in mangrove sediments

This paper presents results related to the occurrence and distribution of estrogens along the Brazilian coast. Three mangrove areas were chosen to evaluate the presence of estrogens in surface sediments of mangrove forests. The presence of estrogens was observed in all studied sites. 17-α-Ethinylestradiol (EE2), a synthetic estrogen, was the most common and has been found in higher concentration (0.45-129.78 ng/g) compared to 17-β-estradiol (E1) and estrone (E2) (both being natural estrogens). The concentrations of E1 and E2 ranged from 0.02 to 49.27 ng/g and 0.03 to 39.77 ng/g, respectively. Theoretically, under anaerobic conditions EE2 can be reduced to E1 even in environments such as sediments of mangrove forests, which are essentially anaerobic. Even if the concentrations of estrogens seem to be insignificant in some samples, the effects remain uncertain.

A diversity of SERCA Ca2+ pump inhibitors

The SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) is probably the most extensively studied membrane protein transporter. There is a vast array of diverse inhibitors for the Ca2+ pump, and many have proved significant in helping to elucidate both the mechanism of transport and gaining conformational structures. Some SERCA inhibitors such as thapsigargin have been used extensively as pharmacological tools to probe the roles of Ca2+ stores in Ca2+ signalling processes. Furthermore, some inhibitors have been implicated in the cause of diseases associated with endocrine disruption by environmental pollutants, whereas others are being developed as potential anticancer agents. The present review therefore aims to highlight some of the wide range of chemically diverse inhibitors that are known, their mechanisms of action and their binding location on the Ca2+ ATPase. Additionally, some ideas for the future development of more useful isoform-specific inhibitors and anticancer drugs are presented.

Nacre-driven water-soluble factors promote wound healing of the deep burn porcine skin by recovering angiogenesis and fibroblast function

To assess the recovery effect of water-soluble components of nacre on wound healing of burns, water-soluble nacre (WSN) was obtained from powdered nacre. Alterations to WSN-mediated wound healing characteristics were examined in porcine skin with deep second-degree burns; porcine skin was used as a proxy for human. When WSN was applied to a burned area, the burn-induced granulation sites were rapidly filled with collagen, and the damaged dermis and epidermis were restored to the appearance of normal skin. WSN enhanced wound healing recovery properties for burn-induced apoptotic and necrotic cellular damage and spurred angiogenesis. Additionally, WSN-treated murine fibroblast NIH3T3 cells showed increased proliferation and collagen synthesis. Collectively, the findings indicate that WSN improves the process of wound healing in burns by expeditiously restoring angiogenesis and fibroblast activity. WSN may be useful as a therapeutic agent, with superior biocompatibility to powdered nacre, and evoking less discomfort when applied to a wounded area.

Hepatic transcriptomic and metabolomic responses in the stickleback (Gasterosteus aculeatus) exposed to environmentally relevant concentrations of dibenzanthracene

A three-spined stickleback (Gasterosteus aculeatus) cDNA array and one-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy-based metabolomics approach, together with individual biomarkers,were employed to investigate the responses of male sticklebacks to polycyclic aromatic hydrocarbon exposure. Fish were exposed to 1,2:5,6-dibenzanthracene (DbA) at concentrations between 0.01 and 50 microg per liter dissolved in the ambient water for four days, and hepatic transcript and metabolite profiles were determined in comparison with those of solvent-exposed controls. Induction of gene expression was apparent for cytochrome P450 1A (CYP1A) and CYP2-family monooxygenases and these responses were strongly correlated with DbA exposure concentrations (for CYP1A r > 0.996). Expression of suites of genes related to bile acid biosynthesis, steroid metabolism, and endocrine function were also affected, as demonstrated by gene ontology analyses. Expression changes in selected genes were confirmed by real-time PCR. Metabolomics highlighted notable changes in concentrations of taurine, malonate, glutamate, and alanine. These statistically significant responses to environmentally relevant concentrations of DbA at the transcriptomic and metabolomic levels provided sensitive markers characteristic of environmentally relevant low-level DbA exposure. Metabolic pathways were identified where both gene expression and metabolite concentrations were altered in response to DbA.

Kinetics of hepatic phase I and II biotransformation reactions in eight finfish species

Hepatic microsomes and cytosols of channel catfish (Ictalurus punctatus), rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar), red tilapia (Oreochromis sp.), largemouth bass (Micropterussalmoides), striped bass (Morone saxatilis), hybrid striped bass (M. saxatilis x M. crysops), and bluegill (Lepomis macrochuris) (n=8) were used to study the kinetics of phase I (ECOD, EROD, PROD, BROD) and phase II (UDP-glucuronosyltransferase (UDPGT)-, sulfotransferase (ST)- and glutathione-s-transferase (GST)-mediated) reactions. The best catalytic efficiency for ECOD and GST activities was performed by channel catfish, Atlantic salmon, rainbow trout and tilapia. The highest EROD catalytic efficiency was for Atlantic salmon. None of the species had either PROD or BROD activities. Rainbow trout had very similar UDPGT catalytic efficiency to tilapia, channel catfish, Atlantic salmon, largemouth bass and bluegill. Sulfotransferase conjugation had no significant differences among the species. In summary, tilapia, channel catfish, Atlantic salmon and rainbow trout had the best biotransforming capabilities; striped bass, hybrid striped bass and bluegill were low metabolizers and largemouth bass shared some capabilities with both groups.

Molecular targets of TBBPA in zebrafish analysed through integration of genomic and proteomic approaches

Tetrabromobisphenol-A (TBBPA) is nowadays one of the most frequently used brominated flame retardants (BFRs) and can be considered as a high production volume chemical. Over the last decade, numerous reports of increasing concentrations of BFRs in the environment and humans have been published. However, the toxicological knowledge on TBBPA, and more specifically its molecular mode of action, is rather fragmentary. In this study two populations of adult zebrafish (Danio rerio) were exposed for 14 days to 0.75 microM and 1.5 microM TBBPA. Subsequently, we employed a combined transcriptomic and proteomic approach to evaluate the molecular effects of TBBPA in zebrafish liver. Oligonucleotide microarrays were used to study the effects on gene expression levels. These results were validated through real-time PCR. The proteome of the liver was analysed by means of differential in-gel electrophoresis (DiGE), an innovative application of traditional 2D-PAGE. Combination of the extracted datasets allowed reassembling of individual molecular responses into a comprehensive overview of affected molecular pathways. Interpretation of the results depicted an interference of thyroid and Vitamin A homeostasis in the exposed zebrafish, TBBPA also elicited responses indicating onset of oxidative stress and general stress responses. Additionally, numerous differentially expressed transcripts could be associated with defence mechanisms or corresponded to metabolizing enzymes. Furthermore, cellular metabolism was clearly affected, illustrated as disturbance of e.g. lipid, carbohydrate, and organic acid metabolic processes. Summarizing, these results enabled us to hypothesize several working mechanisms of TBBPA and demonstrated the potential of a combined genome and proteome approach to generate detailed mechanistic toxicological information.

Characterization and ontogenic study of novel steroid-sulfating SULT3 sulfotransferases from zebrafish

In vertebrates, sulfation as catalyzed by members of the cytosolic sulfotransferase (SULT) family has been suggested to be involved in the homeostasis of steroids. To establish the zebrafish as a model for investigating how sulfation functions to regulate steroid metabolism during the developmental process, we have embarked on the identification of steroid-sulfating SULTs in zebrafish. By searching the GenBank database, we identified two putative cytosolic SULT sequences from zebrafish, designated SULT3 ST1 and ST2. The recombinant proteins of these two zebrafish SULT3 STs were expressed in and purified from BL21 (DE3) cells transformed with the pGEX-2TK expression vector harboring SULT3 ST1 or ST2 cDNA. Upon enzymatic characterization, purified SULT3 ST1 displayed the strongest sulfating activity toward 17beta-estradiol among the endogenous substrates tested, while SULT3 ST2 exhibited substrate specificity toward hydroxysteroids, particularly dehydroepiandrosterone (DHEA). The pH-dependence and kinetic constants of these two enzymes with 17beta-estradiol and DHEA were determined. A developmental expression study revealed distinct patterns of the expression of SULT3 ST1 and ST2 during embryonic development and throughout the larval stage onto maturity. Collectively, these results imply that these two steroid-sulfating SULT3 STs may play differential roles in the metabolism and regulation of steroids during zebrafish development and in adulthood.

Nonylphenol in the environment: a critical review on occurrence, fate, toxicity and treatment in wastewaters

Nonylphenol is a toxic xenobiotic compound classified as an endocrine disrupter capable of interfering with the hormonal system of numerous organisms. It originates principally from the degradation of nonylphenol ethoxylates which are widely used as industrial surfactants. Nonylphenol ethoxylates reach sewage treatment works in substantial quantities where they biodegrade into several by-products including nonylphenol. Due to its physical-chemical characteristics, such as low solubility and high hydrophobicity, nonylphenol accumulates in environmental compartments that are characterised by high organic content, typically sewage sludge and river sediments, where it persists. The occurrence of nonylphenol in the environment is clearly correlated with anthropogenic activities such as wastewater treatment, landfilling and sewage sludge recycling. Nonylphenol is found often in matrices such as sewage sludge, effluents from sewage treatment works, river water and sediments, soil and groundwater. The impacts of nonylphenol in the environment include feminization of aquatic organisms, decrease in male fertility and the survival of juveniles at concentrations as low as 8.2 microg/l. Due to the harmful effects of the degradation products of nonylphenol ethoxylates in the environment, the use and production of such compounds have been banned in EU countries and strictly monitored in many other countries such as Canada and Japan. Although it has been shown that the concentration of nonylphenol in the environment is decreasing, it is still found at concentrations of 4.1 microg/l in river waters and 1 mg/kg in sediments. Nonylphenol has been referred to in the list of priority substances in the Water Frame Directive and in the 3rd draft Working Document on Sludge of the EU. Consequently there is currently a concern within some industries about the possibility of future regulations that may impose the removal of trace contaminants from contaminated effluents. The significance of upgrading sewage treatment works with advanced treatment technologies for removal of trace contaminants is discussed.

Vitellogenin as a biomarker of exposure to estrogenic compounds in aquatic invertebrates: a review

Vitellogenins (Vg) are the major precursor of the egg-yolk proteins, vitellins (Vn), which provide energy reserves for embryonic development in oviparous organisms. In mature females, Vg are generally synthesised in response to endogenous estrogens, such as 17beta-estradiol (E2), released into the bloodstream and then stored in developing oocytes. In males, the Vg gene, although present, is normally silent. However, it may be activated by (xeno)-estrogens. These substances belong to a large and heterogeneous group of environmental contaminants capable of altering endocrine functions in organisms. For this reason, they are named endocrine disrupting chemicals (EDCs). Natural steroidal estrogens [E2, estrone (E1), estriol (E3)] and synthetic chemicals, such as pesticides, polychlorinated biphenyls (PCBs) and household products (surfactants) are estrogenic compounds widespread in aquatic ecosystems. The main sources of contamination mostly stem (or originate) from municipal and industrial effluents, agricultural practices, livestock wastes and sewage treatment plants (STP). Recently, Vg induction, mainly in males and immature females, has been proposed as a useful biomarker to assess estrogenic contamination in aquatic environments. Indeed, estrogenicity of individual chemicals and mixtures has extensively been evaluated, in both laboratory and field studies, albeit mostly in fish. In contrast, limited attention has centred on evaluating xenoestrogen effects in aquatic invertebrates, probably owing to limited knowledge of their endocrinology. This review focuses on a brief description of xenoestrogens and their occurrence in aquatic environments, and on Vg induction in aquatic invertebrates in response to both experimental and environmental exposure to estrogenic compounds. Results of recent field and laboratory studies are presented. In addition, new perspectives about the use of Vg induction as a biomarker of exposure to estrogenic compounds are also discussed.

Hair mercury negatively correlates with calcium pump activity in human term newborns and their mothers at delivery

BACKGROUND

Calcium homeostasis is a known target of several environmental toxicants including lead and mercury.

OBJECTIVE

Our goal was to determine the relationship between Hg exposure and erythrocyte Ca pump activity in women at delivery and in their newborns.

METHODS

We determined total Hg as well as Pb concentrations in 81 hair and blood samples obtained at delivery. Basal and calmodulin-stimulated Ca pump activity was measured in red blood cells from cord blood and maternal erythrocyte plasma membranes.

RESULTS

Maternal hair Hg negatively correlates with Ca pump activity in maternal and cord blood erythrocytes. Pb and Hg both independently correlate negatively with Ca pump activity without any statistically significant interaction. After adjustment for potential confounders, Pb and Hg explain about 30% and 7% of total variance of Ca pump activity in newborns and mothers, respectively.

CONCLUSION

Our findings confirm results reported in previous experimental studies and support the use of biomarkers in newborns from general population.

The widely utilized brominated flame retardant tetrabromobisphenol A (TBBPA) is a potent inhibitor of the SERCA Ca2+ pump

TBBPA (tetrabromobisphenol A) is currently the most widely used type of BFR (brominated flame retardant) employed to reduce the combustibility of a large variety of electronic and other manufactured products. Recent studies have indicated that BFRs, including TBBPA, are bio-accumulating within animal and humans. BFRs including TBBPA have also been shown to be cytotoxic and potentially endocrine-disrupting to a variety of cells in culture. Furthermore, TBBPA has specifically been shown to cause disruption of Ca2+ homoeostasis within cells, which may be the underlying cause of its cytotoxicity. In this study, we have demonstrated that TBBPA is a potent non-isoform-specific inhibitor of the SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) (apparent K(i) 0.46-2.3 microM), thus we propose that TBBPA inhibition of SERCA contributes in some degree to Ca2+ signalling disruption. TBBPA binds directly to the SERCA without the need to partition into the phospholipid bilayer. From activity results and Ca2+-induced conformational results, it appears that the major effect of TBBPA is to decrease the SERCA affinity for Ca2+ (increasing the K(d) from approx. 1 microM to 30 microM in the presence of 10 microM TBBPA). Low concentrations of TBBPA can quench the tryptophan fluorescence of the SERCA and this quenching can be reversed by BHQ [2,5-di-(t-butyl)-1,4-hydroquinone] and 4-n-nonylphenol, but not thapsigargin, indicating that TBBPA and BHQ may be binding to similar regions in the SERCA.

Effects of endocrine disruptors on dehydroepiandrosterone sulfotransferase and enzymes involved in PAPS synthesis: genomic and nongenomic pathways

BACKGROUND

Sulfation plays an important role both in detoxification and in the control of steroid activity. Studies in rodents have shown that the conversion of dehydroepiandrosterone (DHEA) to DHEA-sulfate is involved in learning and the memory process.

METHODS

The effects of a range of plasticizers and related compounds commonly encountered in the environment were evaluated kinetically against human DHEA sulfotransferase (SULT 2A1) and by reverse transcriptase-polymerase chain reaction (RT-PCR) against several enzymes involved in the synthesis of the sulfotransferase cofactor adenosine 3'-phosphate 5'-phosphosulfate (PAPS).

RESULTS

We found that several of the chemicals acted as competitive inhibitors of SULT 2A1 (K(i) for 4-tert-octylphenol is 2.8 microM). Additionally, after treatment of TE 671 cells with 0.005-0.5 microM 4-n-octylphenol, bis(2-ethylhexyl)phthalate, and diisodecyl phthalate, real-time RT-PCR showed dose-dependent decreases in the steady-state mRNA levels of cysteine dioxygenase type I, sulfite oxidase, and 3'-phosphate 5'-phosphosulfate synthase I.

CONCLUSIONS

These data suggest that environmental contaminants may exert effects on neuronal function both by direct inhibition of sulfotransferase enzymes and by interrupting the supply of PAPS, which has wider implications for endocrine disruption and xenobiotic metabolism.

First evidence of altered vitellogenin-like protein levels in clam Tapes philippinarum and in cockle Cerastoderma glaucum from the Lagoon of Venice

Possible xenoestrogenic effects were investigated, for the first time, in two bivalve species from the Lagoon of Venice (Italy): the clam Tapes philippinarum and the cockle Cerastoderma glaucum. Bivalves were collected far from their reproductive phase at the very early stage of gametogenesis (January), and in the pre-spawning period (June) in six sites. Vitellogenin (Vg)-like proteins (a biomarker of exposure to estrogenic compounds) were measured by the alkali-labile phosphate method (ALP), in both haemolymph and digestive gland from males and females (when it was possible to distinguish sex by microscopic observation of gonadal tissue). Haemolymph calcium concentrations (a parameter considered closely related to the presence of Vg-like proteins) and the bivalve condition index (CI) were also measured. In both seasons, bivalves collected at Campalto (near a sewage treatment plant) and Marghera (a highly contaminated area) had higher Vg-like protein levels, particularly in haemolymph, than animals from the other sampling sites. Interestingly, CI had high values in these polluted sites. In June only, Vg-like proteins and Ca(2+) levels in haemolymph exhibited similar trends in both bivalve species at most sampling sites. The responsiveness of bivalves to environmental xenoestrogens was higher in June, allowing better discrimination among sites. The present study demonstrates that animals from highly polluted areas have increased Vg-like protein levels. As endocrine disruption due to exposure to estrogenic compounds may cause fertility reduction, alterations in the sex ratio, and a decrease in reproductive rate, a condition of potential risk for bivalve populations in estuarine areas is highlighted.

Effects of alkylphenols on glycerophospholipids and cholesterol in liver and brain from female Atlantic cod (Gadus morhua)

Offshore oil production releases large amounts of lipophilic compounds in produced water into the ocean. In 2004, 143 million m(3) produced water, containing approximately 13 tons of long-chain (>C(4)) alkylphenols (AP), was discharged from installations in the Norwegian sector of the North Sea. Long-chain APs are known to cause endocrine disruption in a number of species. However, relatively little is known about their long-term effects in the marine environment. In the present study, Atlantic cod (Gadus morhua) were exposed (0.02 to 80 mg AP/kg) to a mixture (1:1:1:1) of APs (4-tert-butylphenol, 4-n-pentylphenol, 4-n-hexylphenol and 4-n-heptylphenol) or 17 beta-estradiol (5 mg E2/kg) for 5 weeks and the effect on the fatty acid profile and cholesterol content in the membrane lipids from the liver and the brain was studied. We also determined the interaction between different para-substituted APs and glycerophospholipids (native phospholipids extracted from cod liver and brain) and model phosphatidylcholine (PC 16:0/22:6 n-3) in monolayers with the Langmuir-Blodget technique. The study demonstrated that APs and E2 alter the fatty acid profile in the polar lipids (PL) from the liver to contain more saturated fatty acids (SFA) and less n-3 polyunsaturated fatty acids (n-3 PUFA) compared with control. In the brain of the exposed groups a similar effect was demonstrated, although with higher saturation of the fatty acids found in the neutral lipids (mainly cholesterol ester), but not in the polar lipids. The AP and E2 exposure also gave a decline in the cholesterol levels in the brain. The in vitro studies showed that APs increased the mean molecular areas of the PLs in the monolayers at concentrations down to 5 microM, most likely due to intercalation of the APs between PL molecules. The increase in molecular area increased with the length of the alkyl side chain.

A novel matrix protein p10 from the nacre of pearl oyster (Pinctada fucata) and its effects on both CaCO3 crystal formation and mineralogenic cells

A novel matrix protein, designated as p10 because of its apparent molecular mass of 10 kDa, was isolated from the nacreous layer of pearl oyster (Pinctada fucata) by reverse-phase high-performance liquid chromatography. In vitro crystallization experiments showed that p10 could accelerate the nucleation of calcium carbonate crystals and induce aragonite formation, suggesting that it might play a key role in nacre biomineralization. As nacre is known to contain osteogenic factors, two mineralogenic cell lines, MRC-5 fibroblasts and MC3T3-E1 preosteoblasts, were used to investigate the biological activity of p10. The results showed that p10 could increase alkaline phosphatase activity, an early marker of osteoblast differentiation, while the viability of MRC-5 and MC3T3-E1 remained unchanged after treatment of p10. Taken together, the findings led to identification of a novel matrix protein from the nacre of P. fucata that plays a role in both the mineral phase and in the differentiation of the cells involved in biomineralization.

Effects of xenobiotics and steroids on renal and hepatic estrogen metabolism in lake trout

Experiments were conducted to (1) elucidate the biochemical pathways of E2 metabolism in the lake trout (Salvelinus namaycush) kidney and liver, and (2) test the hypothesis that specific xenobiotics and endogenous steroids inhibit E2 metabolism by these tissues. Kidney and liver tissue fragments from immature lake trout were incubated in vitro in the presence of radiolabelled E2 plus various xenobiotics or steroids. E2 metabolites were identified by liquid chromatography/mass spectroscopy, and quantified by liquid scintillation spectroscopy. A major metabolite produced by both tissues was an unidentified hydroxylated estrogen metabolite (E2-OH) with a molecular mass of 288 that was not estriol (16-OH-E2), but possibly 7alpha-OH-E2 or 2-OH-E2 (catecholestrogen). Both tissues also produced estradiol-17-glucuronide (E2-17-G), estradiol-17-sulfate (E2-17-S), and estradiol-3-glucuronide (E2-3-G). Compared to the kidney, the liver produced half the amount of conjugated metabolites, but twofold more E2-OH. The following xenobiotics (at a concentration of 100 microM) inhibited the production of water-soluble (i.e., conjugated) E2 metabolites by both the kidney and liver: 4,4'-(OH)2-3,3',5,5'- tetrachlorobiphenyl (4,4'-OH-TCB), bisphenol A (BPA), tetrabromobisphenol A (TB-BPA), tetrachlorobisphenol A (TC-BPA), tribromophenol (TBP), trichlorophenol (TCP), and pentachlorophenol (PCP). The alkylphenols, 4-n-nonylphenol (NP), and 4-octylphenol (OP), and 2,2',4,4'-tetrabromodiphenyl ether (TBDE) had no significant effect on E2 metabolism by either tissue. Testosterone and 17alpha,20beta-dihydroxy-4-pregnen-3-one inhibited the production of conjugated E2 metabolites by both the kidney and liver. Cortisol and 11-ketotestosterone inhibited E2 metabolism by the liver only. The median inhibitory concentrations (IC50) for 4,4'-OH-TCB ranged from 7-32 microM in the kidney and 0.6-1.6 microM in the liver. For BPA, IC50's ranged from 40-108 microM in the kidney and 11-18 microM in the liver. Low doses (0.1 microM) of 4,4'-OH-TCB and BPA significantly increased estrogen metabolism in the kidney. The results suggest that certain estrogenic xenobiotics and endogenous steroids may inhibit the phase II conjugation of E2 by the kidney and liver of lake trout, and some of the known biological effects of these compounds are likely mediated, at least partially, by this mechanism of action.

The pesticide heptachlor affects steroid hormone secretion in isolated follicular and luteal cells of rat

Heptachlor, a chlorinated hydrocarbon pesticide, suppresses the production of progesterone and estradiol in the female rat in vivo or in isolated ovaries in vitro. In this study the effect of heptachlor on steroid hormone production by isolated rat luteal and follicular cells, in the presence of two precursor hormones was investigated. Ovaries were isolated from anesthetized mature normocyclic virgin rats (3 to 4 months old), under sterile conditions. Corpora lutea and follicles were microscopically dissected out and separately enzymatically dispersed with collagenase at 37 degrees C. Viable cells collected after centrifugation were used at a concentration of approximately 2.5 x 10(5) cells/10 mL. Both luteal and follicular cell preparations were separately incubated overnight (15 h) at 37 degrees C in the presence of pregnenolone (P5) and androstenedione (A4) at a concentration of 6.0 nmol/L each, and heptachlor at either 0.12 microg/mL (low dose) or 1.20 microg/mL (high dose) (test cells) or in the absence of heptachlor (control cells). At the end of the incubations, progesterone and estradiol 17beta levels were analyzed in the incubation media. The results indicate that heptachlor significantly suppressed the production of both progesterone and estradiol in both cell types in a dose related manner even in the presence of A4 and P5 as precursor hormones (P<0.05).

Sulfotransferase activities towards xenobiotics and estradiol in two marine fish species (Mullus barbatus and Lepidorhombus boscii): characterization and inhibition by endocrine disrupters

We have characterized hepatic phenol sulfotransferase (SULT) activities in two benthic fish species, Mullus barbatus and Lepidorhombus boscii, using p-nitrophenol, dopamine, 17beta-estradiol, 4-nonylphenol, and 1-naphthol as substrates. High affinity sulfation of 17beta-estradiol was observed in both species (Km=28-75 nM), suggesting the presence of a specific estrogen sulfotransferase that catalyzes the formation of estradiol-3 sulfate. Among the tested compounds, 1-naphthol was the most effective substrate for sulfation, with Vmax/Km ratios several hundred-fold higher than the other substrates examined. Both species sulfated the tested compounds, but only M. barbatus was able to sulfate dopamine. We also tested the inhibitory effects of common marine pollutants with estrogenic (4-nonylphenol) and androgenic (tributyltin, triphenyltin) properties on p-nitrophenol and 17beta-estradiol SULT activities. 4-Nonylphenol and triphenyltin inhibited sulfation of both substrates at micromolar concentrations in both species. However, tributyltin was only effective against SULTs from L. boscii, again at micromolar concentrations. The data indicate that M. barbatus and L. boscii are able to sulfate a range of xenobiotics and endogenous compounds, and inhibition of these activities by environmental pollutants may contribute to the known toxic effects of these compounds.

Steroid levels and steroid metabolism in the mussel Mytilus edulis: the modulating effect of dispersed crude oil and alkylphenols

Significant amounts of oil and alkylphenols are released into the sea by petroleum installations as a result of discharges of produced water. Some of these pollutants elicit estrogenic responses in fish, but their effects on the endocrine system of molluscs are largely unknown. In this study, mussels Mytilus edulis were exposed to North Sea oil (O) and the mixture of North Sea oil+alkylphenols (OAP), and the effects on tissue steroid levels and steroid metabolism (P450-aromatase and estradiol-sulfotransferase) were monitored. Levels of free testosterone and free estradiol were much higher in gonad tissue than in peripheral tissue, whereas esterified steroids (released after saponification) were of the same order of magnitude in both tissues. Levels of free steroids determined in gonads were not affected by exposure, but esterified steroids significantly increased in OAP exposed mussels (up to 2.4-fold). The sulfation of estradiol was investigated as a conjugation pathway, and increased activities were observed in digestive gland cytosol of both O and OAP exposure groups (up to 2.8-fold). Additionally, increased P450-aromatase activity was determined in OAP exposed mussels (up to three-fold, both in gonad and digestive gland), but not in the O group. Altogether, the results indicate that North Sea oil leads to increased sulfation of estradiol, and that in combination with alkylphenols, additional alterations are observed: increased P450-aromatase, and increased levels of esterified-steroids in gonads. Nonetheless, mussels are able to maintain gonad concentrations of free steroids unaltered, possibly via homeostatic mechanisms such as the conjugation with fatty acid or the formation of sulphate conjugates.

Endocrine alteration in juvenile cod and turbot exposed to dispersed crude oil and alkylphenols

Juvenile Atlantic cod (Gadus morhua) and turbot (Scophthalmus maximus) were exposed for 3 weeks in a continuous water flow to 0.5 ppm of dispersed North Sea crude oil, 0.5 ppm of dispersed North Sea crude oil spiked with 0.1 ppm of a mixture of alkylphenols (offshore oil production), and 30 ppb of nonylphenol (NP). As potential markers of endocrine alteration, key enzymatic activities involved in both synthesis (17beta-hydroxysteroid dehydrogenases and P450 aromatase) and metabolism (liver UDP-glucuronosyltransferases (UGT) and sulfotransferases) of steroids were assessed together with circulating levels of testosterone and estradiol in plasma. NP-exposed turbot had lower ovarian P450 aromatase, lower levels of testosterone and estradiol in plasma, and lower glucuronidation rates of sex steroids than those from the control group. In contrast, higher liver UGT-testosterone, and a trend towards higher P450 aromatase was detected in oil-exposed specimens. Those exposed to the combination oil+alkylphenols had lower levels of estradiol in plasma than controls, and no significant effects on any the enzymatic activities tested was observed. All these alterations were more evident in turbot than in cod. In fact, apart from a higher glucuronidation rate of estradiol detected in the liver of NP-exposed cod, no significant differences were observed between control and exposed cod.

17Beta-hydroxysteroid dehydrogenase (17beta-HSD) in scleractinian corals and zooxanthellae

Steroid metabolism studies have yielded evidence of 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity in corals. This project was undertaken to clarify whether there are multiple isoforms of 17beta-HSD, whether activity levels vary seasonally, and if zooxanthellae contribute to activity. 17Beta-HSD activity was characterized in zooxanthellate and azooxanthellate coral fragments collected in summer and winter and in zooxanthellae cultured from Montipora capitata. More specifically, 17beta-HSD activity was characterized with regard to steroid substrate and inhibitor specificity, coenzyme specificity, and Michaelis constants for estradiol (E2) and NADP+. Six samples each of M. capitata and Tubastrea coccinea (three summers, three winters) were assayed with E2 and NADP+. Specific activity levels (pmol/mg protein) varied 10-fold among M. capitata samples and 6-fold among T. coccinea samples. There was overlap of activity levels between summer and winter samples. NADP+/NAD+ activity ratios varied from 1.6 to 22.2 for M. capatita, 2.3 to 3.8 for T. coccinea and 0.7 to 1.1 for zooxanthellae. Coumestrol was the most inhibitory of the steroids and phytoestrogens tested. Our data confirm that corals and zooxanthellae contain 17beta-HSD and are consistent with the presence of more than one isoform of the enzyme.

Calcium-mediated aponecrosis plays a central role in the pathogenesis of estrogenic chemical-induced neurotoxicity

Estrogen is traditionally associated with females but is also present in males, and influences aspects of brain chemistry and brain morphology in males, females and also during prenatal development. Humans as well as animals are additionally exposed to environmental products that mimic estrogen activity, also known as endocrine disrupters (EDCs). This hypothesis article investigates the role of estrogen (and also EDCs) in the brain and how it influences the Ca2+ pathway. Ca2+ and its movement in and out of the cell is an extremely important ion controlling normal cell physiology. Any dysfunction in the movement from outside to inside the cell or between organelles may have fundamentally negative effects and the disturbance may even lead to apoptosis and/or necrosis. Therefore we consider whether estrogen and EDCs may alter the Ca2+ physiology and whether these changes may be one of the main causes of interference in physiology that is seen when humans and animals are exposed to EDCs. We come to the conclusion that on a molecular level Ca2+ and Ca2+ fluxes ([Ca2+]i, endocrine disrupting chemicals, redox modulation, mitochondria and cytochrome c followed by apoptosis, necrosis or most likely aponecrosis may contribute to chemical-mediated developmental toxicity. Similarly, we hypothesize that calcium-mediated aponecrosis do not only play a central role in the pathophysiology of estrogenic chemical-induced neurotoxicity, but can contribute to chemical-mediated developmental toxicity in general, thereby affecting almost all cells and organs of the living organism.

Effects of selected xenoestrogens on liver peroxisomes, vitellogenin levels and spermatogenic cell proliferation in male zebrafish

Environmental estrogenic compounds or xenoestrogens can mimic natural estrogens and cause a variety of adverse effects on aquatic wildlife. The purpose of the present work was to investigate if xenoestrogens are able to cause proliferation of liver peroxisomes using zebrafish (Danio rerio) as a model. Adult male zebrafish were exposed for 15 days to 17beta-estradiol (E2) and the xenoestrogens dibutylphthalate (DBP), methoxychlor (MXC), 4-tert-octylphenol (OP) and 17alpha-ethynylestradiol (EE2). All five tested compounds caused significant proliferation of liver peroxisomes (p < 0.05) as indicated by increased peroxisomal surface and numerical densities and elevated activities of the peroxisomal beta-oxidation enzyme acyl-CoA oxidase (AOX). In the case of DBP, MXC and E2, positive significant correlations between peroxisomal density parameters and AOX were found. The treatments did not produce gross alterations in testis histology, but spermatogenic cell proliferation was disturbed in E2 and EE2-treated groups and vitellogenin levels increased significantly in fish exposed to MXC, OP, EE2 and E2 with respect to controls. Furthermore, a significant correlation between vitellogenin levels and AOX activity was found for MXC, OP and EE2 treatments, suggesting that for the latter xenoestrogens early estrogenic effects are associated with liver peroxisome proliferation. No such association occurred with typical peroxisome proliferators such as DBP.