Time- and dose-dependent detoxification and reproductive endocrine disruption induced by tetrabromobisphenol A (TBBPA) in mussel Mytilus galloprovincialis

As a typical brominated flame retardant (BFR), tetrabromobisphenol A (TBBPA) has been frequently detected in both biotic and abiotic matrices in marine environment. Our previous study found that genes related to metabolism phase I/II/III as well as steroid metabolism in Mytilus galloprovincialis were significantly altered by TBBPA treatment. However, the time- and dose-dependent response profiles of these genes to TBBPA exposure were rarely reported. In this study, the time- and dose-dependent effects of TBBPA on detoxification and reproductive endocrine disruption in M. galloprovincialis were explored by evaluating the responses of related gene expressions, enzymatic activities and gametogenesis to different concentrations of TBBPA (0.6, 3, 15, 75 and 375 mu g/L) for different durations (14, 21 and 28 days). The results showed that the TBBPA accumulation increased linearly with the increases of exposure time and dose. Cytochrome P450 family 3 (CYP3A1-like) cooperated with CYP4Y1 for phase I biotransformation of TBBPA in mussels. The dose-response curves of phase II/III genes (glutathione-Stransferase (GST), P-glycoprotein (ABCB), and multidrug resistance protein (ABCC)) showed similar response profiles to TBBPA exposure. The common induction of phase I/II/III (CYPs, GST, ABCB and ABCC) suggested TBBPA detoxification regulation in mussels probably occurred in a step-wise manner. Concurrently, direct sulfation mediated by sulfotransferases (SULTs) on TBBPA was also the vital metabolic mechanism for TBBPA detoxification, which was supported by the coincidence between up-regulation of SULT1B1 and TBBPA accumulation. The significant promotion of steroid sulfatase (STS) might result from TBBPA-sulfate catalyzed by SULT1B1 due to its chemical similarity to estrone-sulfate. Furthermore, the promotion of gametogenesis was consistent with the induction of STS, suggesting that STS might interrupt steroids hydrolysis process and was responsible for reproductive endocrine disruption in M. galloprovincialis. This study provides a better understanding of the detoxification and endocrine-disrupting mechanisms of TBBPA

Genome Sequencing-Based Mining and Characterization of a Novel Alginate Lyase from <i>Vibrio alginolyticus</i> S10 for Specific Production of Disaccharides

Alginate oligosaccharides prepared by alginate lyases attracted great attention because of their desirable biological activities. However, the hydrolysis products are always a mixture of oligosaccharides with different degrees of polymerization, which increases the production cost because of the following purification procedures. In this study, an alginate lyase, Alg4755, with high product specificity was identified, heterologously expressed, and characterized from Vibrio alginolyticus S10, which was isolated from the intestine of sea cucumber. Alg4755 belonged to the PL7 family with two catalytic domains, which was composed of 583 amino acids. Enzymatic characterization results show that the optimal reaction temperature and pH of Alg4755 were 35 °C and 8.0, respectively. Furthermore, Alg4755 was identified to have high thermal and pH stability. Moreover, the final hydrolysis products of sodium alginate catalyzed by Alg4755 were mainly alginate disaccharides with a small amount of alginate trisaccharides. The results demonstrate that alginate lyase Alg4755 could have a broad application prospect because of its high product specificity and desirable catalytic properties

Environmental status and early warning value of the pollutant Semicarbazide in Jincheng and Sishili Bays, Shandong Peninsula, China

A verified method for measuring Semicarbazide (SEM) in seawater, sediments, and shellfish was developed based on ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). A total of 30 stations were radially distributed in jincheng and Sishili Bays in the Bohai and Yellow Seas, and 1025 monitoring data were collected in 41 voyages, 615 seawater samples, 320 sediment samples and 90 shellfish samples. The concentration ranged from 0.011 mu g/L to 0.093 mu g/L and 0 to 0.75 mu g/kg in seawater and shellfish respectively, but SEM in sediment was all below the limit of detection. Temporal and spatial distribution of SEM was investigated using multivariate analysis to estimate the degree of SEM pollution. Based on the SEM concentration in the three sample types, together with our previous findings, early warning values were deduced for SEM in seawater, and the developed method overcame shortcomings with existing technologies. The results may be helpful to draft national baseline values for SEM in seawater and sediments, and provide a scientific basis for assessing the impacts of SEM on marine ecology and human health. (C) 2016 Elsevier B.V. All rights reserved

UPLC-MS/MS Method for Simultaneous Determination of Three Major Metabolites of Mequindox in Holothurian

This study developed an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of three major metabolites of mequindox, including 3-methyl-quinoxaline-2-carboxylic acid, 1-desoxymequindox, and 1,4-bisdesoxymequindox (MQCA, 1-DMEQ, and BDMEQ), in holothurian. Target analytes were simplified with ultrasound-assisted acidolysis extracted without complicated enzymolysis steps. After that, each sample was centrifuged and purified by an Oasis MAX cartridge. Then, the processed samples were separated and monitored by UPLC-MS/MS. This developed method has been validated according to FDA criteria. At fortified levels of 2, 10, and 20 μg/kg, recoveries ranged from 82.5% to 93.5% with the intraday RSD less than 7.27% and interday RSD less than 11.8%. The limit of detection (LOD) of all the three metabolites ranged from 0.21 to 0.48 μg/kg, while the limit of quantification (LOQ) ranged from 0.79 to 1.59 μg/kg. On application to commercial samples, 14 of 20 samples were detected positive for the three target analytes, with positive rate at 70 percentage. The result indicated that this method was specific, sensitive, and suitable for the quantification and conformation of the three major metabolites of MEQ in holothurian