Development and application of a monoclonal antibody-based sandwich ELISA for quantification of Japanese medaka (Oryzias latipes) vitellogenin

Nonsteroidal anti-inflammatory drugs act as endocrine disruptors in Astyanax lacustris (Teleostei: Characidae) reproduction: An ex vivo approach

Pharmaceutical products can act as endocrine-disrupting compounds (EDCs), affecting the physiological processes of animals, such as development or reproduction. This study aimed to investigate the influence of different concentrations of nonsteroidal anti-inflammatory drugs (NSAIDs) diclofenac (DCF) and ibuprofen (IBU) alone and mixed (MIX) on gonadotropin gene expression and gonadal steroid release using Astyanax lacustris pituitary and testes explant systems, respectively. The explant organs were maintained for 12 h in Leibovitz (L-15) medium supplemented with 0, 0.1, 1, 10, 100, and 1000 ng L-1 of DCF, IBU, and MIX (ratio 1:1 of the same concentrations of DCF and IBU alone) and gonadotropin releasing-hormone (cGnRH2) stimulation in pituitary explants and human chorionic gonadotropin (hCG) stimulation in testes explants. The pituitary glands and the media from the testicular explants were collected for gene expression analysis including the β subunit of the follicle-stimulating hormone (fshβ) and luteinizing hormone (lhβ) and secreted gonadal steroid concentration analysis, respectively. Both DCF and IBU (alone and mixed) decreased pituitary gene expression of fshβ and lhβ and this inhibitory effect was evident even at low concentrations. In the testes, DCF and IBU did not change the levels of estradiol, and both pharmaceuticals increased the release of 11-ketotestosterone at low doses, while only IBU decreased the levels of testosterone in all concentrations. IBU's inhibitory effect in the testes was not triggered by the mixture of the two drugs. These results suggest that NSAIDs, may interfere in fish reproduction by acting as EDCs, thereby negatively affecting A. lacustris spermatogenesis and maturation.

Identification of estrogen-like effects and biologically active compounds in river water using bioassays and chemical analysis

The Nackdong River is the longest river in South Korea and passes through major cities that have several industrial complexes, including chemical, electric, and petrochemical complexes, and municipal characteristics such as apartment complexes. Along the river, the Gumi region has an electric industrial complex and an apartment complex that may be possible point sources of xenoestrogens such as phenolic compounds. To identify the causative chemicals for estrogenic activity in the river water of this region, bioassay-directed chemical analysis was performed. All samples from six sampling sites (an upstream point: S1; hot spot points: S2-1, S2-2, and S2-3; and downstream points: S3, and S4) showed estrogenic activity in the E-screen assay, with bio-EEQs (17beta-E(2)-equivalent quantities) ranging from 25.35-677.15 pg/L. Samples from S2-2, the sampling point downstream of the junction of stream water, and domestic and industrial wastewater, contained the highest estrogenic activity. Since the bio-EEQ of the organic acid fraction (F2) of the S2-2 sample had the highest activity (823.25 pg-EEQ/L) and F2 may contain phenolic compounds, GC-MS analyses for phenolic xenoestrogens were conducted with the organic acid fractions of the river water samples. Six estrogenic phenolic chemicals, 4-NP, BPA, 4-t-OP, 4-t-BP, 4-n-OP, and 4-n-HTP, were detected, with the highest concentrations (I-EEQ) found in S2-2 (231.80 pg/L). Among these phenolic chemicals, 4-NP was the most potent estrogen (bio-EEF; 8.12 x1 0(-5)) and acted as a full agonist. Furthermore, 4-NP was present at levels (2.0 microg/L in S2-2) that can induce VTG induction in fish (>1 microg/L). In addition, we confirmed that river water (S2-2) significantly increased serum VTG levels in crucian carp (Carassius auratus) in a fish exposure experiment under laboratory conditions. Therefore, phenolic xenoestrogens, especially 4-NP, may be the main causative compounds responsible for the estrogenic effect on the Nackdong River.

Quantification of Greenland halibut serum vitellogenin: a trip from the deep sea to the mass spectrometer

This paper focuses on the sequential steps involved in developing a technique for quantifying Greenland halibut vitellogenin, a serum protein biomarker, using a comprehensive mass spectrometric approach. In the first phase of this study, in-gel trypsin digestions of serum proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A characteristic band around a molecular mass of 185 kDa, present in the mature female specimens, but absent in the male samples, was identified as vitellognin according to the peptide mass fingerprint obtained by MALDI-MS. Subsequently, MALDI and electrospray ionization tandem mass spectrometry (ESI-MS/MS) analyses were performed on the digest of the vitellogenin band for de novo sequencing. From these studies, a characteristic 'signature' peptide (sequence: FFGQEIAFANIDK) was selected from a list of candidate peptides as a surrogate analytical standard used for quantification purposes. Sample preparation for vitellogenin quantification consisted of a simple one-step overnight trypsin digestion. Samples were spiked with an isotopologue signature peptide standard and analyzed by high-performance liquid chromatography (HPLC) coupled in-line to an electrospray quadrupole-hexapole-quadrupole tandem mass spectrometer, operated in selective reaction monitoring mode. Transitions [(m/z 750.0 --> 1020.4 and 750.0 --> 1205.4) and (754.8 --> 1028.6 and 754.8 --> 1213.2)] were monitored for the signature peptide and the internal standard, respectively. Samples obtained from the field showed that vitellogenin levels were in accordance with fish maturity determined by macroscopic examination of the gonad, proving this technique suitable for measuring vitellogenin as a serum protein biomarker for reproductive maturity in female fish.

Evaluation of the estrogenic potential of river and treated waters in the Paris area (France) using in vivo and in vitro assays

For many years, surface waters have been shown to be contaminated by endocrine-disrupting compounds (EDCs), which can cause adverse effects on human and wildlife growth, development, and reproduction. It is therefore of primary importance to determine if drinking water could be contaminated by EDCs when produced from polluted surface waters. It is also essential to determine if disinfection by-products can account for estrogenic activity in treated waters. The estrogenic potential of river and treated waters was investigated using an in vivo assay. Adult male zebrafish were placed in three drinking water treatment plants (DWTPs) in the Paris area and exposed for 1 month to the two types of waters. After exposure, vitellogenin (VTG) was measured in the plasma of fish using a competitive ELISA. In addition, an in vitro assay (MELN cells) was used to assess the estrogenic potential of 10 major chlorination by-products. No significant induction of VTG was observed in fish exposed to river or treated waters. Among the 10 chlorination by-products tested, only 2-chlorophenol was found to be weakly estrogenic at concentrations up to 1mg/L. Therefore, the risk for the three DWTPs studied to produce drinking water with significant level of estrogenic substances appears to be low.

Transcript and protein environmental biomarkers in fish--a review

The levels of contaminant-affected gene products (transcripts and proteins) are increasingly utilized as environmental biomarkers, and their appropriate implementation as diagnostic tools is discussed. The required characteristics of a gene product biomarker are accurate evaluation using properly normalized absolute units, aiming at long-term comparability of biomarker levels over a wide geographical range and among many laboratories. Quantitative RT-PCR and competitive ELISA are suggested as preferred evaluation methods for transcript and protein, respectively. Constitutively expressed RNAs or proteins which are part of the examined homogenate are suggested as normalizing agents, compensating for variable processing efficiency. Essential characterization of expression patterns is suggested, providing reference values to be compared to the monitored levels. This comparison would enable estimation of the intensity of biological effects of contaminants. Contaminant-independent reference expression patterns should include natural fluctuations of the biomarker level. Contaminant-dependent patterns should include dose response to model contaminants chronically administered in two environmentally-realistic routes, reaching extreme sub-lethal affected levels. Recent studies using fish as environmental sentinel species, applying gene products as environmental biomarkers, and implementing at least part of the depicted methodologies are reviewed.

Effects of tamoxifen, 17α-ethynylestradiol, flutamide, and methyltestosterone on plasma vitellogenin levels of male and female Japanese medaka (Oryzias latipes)

The effects of oral administration of tamoxifen, 17α-ethynylestradiol (EE2), flutamide, and methyltestosterone (MT), on plasma vitellogenin levels of male and female medaka were investigated. Medaka were fed diets containing different concentrations of these chemicals for 7 days, and these plasma vitellogenin levels were measured. Tamoxifen increased significantly the vitellogenin levels in male, but inhibited the normal vitellogenin induction in female in the high concentration groups. EE2 increased significantly vitellogenin levels in both sexes. Flutamide increased significantly the vitellogenin levels in female, but gave no effects on male. MT inhibited the normal vitellogenin induction in female, but increased slightly vitellogenin levels in male without a clear tendency. Administration of tamoxifen, EE2, flutamide, and MT showed the different pattern in vitellogenin levels in both sexes.

Effect of alkylphenols on adult male medaka: plasma vitellogenin goes up to the level of estrous female

The effect that oral administration of four alkylphenols, (1) bisphenol A (BPA), (2) p-t-octylphenol (OP), (3) p-nonylphenol (NP) and (4) p-n-nonylphenol (n-NP), as well as 17α-ethynylestradiol (EE2) had on male medaka fish vitellogenin was investigated. The male medaka was fed diets containing different concentrations of these chemicals for 7 days, after which their plasma vitellogenin levels were measured. Vitellogenin levels up to ≈10(7) ng/ml were found. This value is close to that of the normal estrous female medaka. The median effective concentration (EC(50)) values resulting from BPA, OP, NP and EE2 in the diet were calculated as 1600, 2600, 940 and 0.37 μg/g diet, respectively.