An iron-based metal-organic framework as a novel dispersive solid-phase extraction sorbent for the efficient adsorption of tetrabromobisphenol A from environmental water samples.

For environmental safety, it is important to establish a simple, rapid, and sensitive method for emerging pollutants. Here, a dispersive solid-phase extraction (d-SPE) method based on an iron-based metal-organic framework (Fe-MIL-88-NH2) combined with high-performance liquid chromatography (HPLC) was developed for tetrabromobisphenol A (TBBPA) in water samples. Fe-MIL-88-NH2 was synthesized using a solvothermal method and completely characterized. Fe-MIL-88-NH2 had good water stability and gave a maximum adsorption capacity of 40.97 mg g-1 for TBBPA. The adsorption of TBBPA on Fe-MIL-88-NH2 followed Langmuir adsorption models and a pseudo-second-order kinetic model. The bromine ion and the hydroxyl group of TBBPA could form strong hydrogen bond interactions with the amino protons around the cavity of Fe-MIL-88-NH2, which was in accord with the molecular simulation calculations. Furthermore, several important d-SPE parameters were optimized, such as the amount of materials, extraction time, pH, ionic strength, elution solvent type, and volume. The established method showed good linearity in the concentration range of 0.005-100 µg g-1 (r2 ≥ 0.9996). This method's limits of detection (LOD) and quantification (LOQ) were 0.001 µg g-1 and 0.005 µg g-1, respectively. The recoveries in spiked water samples ranged from 87.5% to 104.9%. The proposed method was applied successfully to detect TBBPA in environmental water samples.

Niche divergence at the intraspecific level in an endemic rare peony (Paeonia rockii): A phylogenetic, climatic and environmental survey.

Ecological factors have received increasing attention as drivers of speciation but also in the maintenance of postspeciation divergence. However, the relative significance of the responses of species to climate oscillations for driving niche divergence or conservatism in the evolution of many species that pass through diverse environments and limited geographical boundaries remains poorly understood. Paeonia rockii (one of the ancient species of Paeonia) comprising two subspecies called Paeonia rockii subsp. rockii and Paeonia rockii subsp. taibaishanica is an endemic, rare, and endangered medicinal plant in China. In this study, we integrated whole chloroplast genomes, and ecological factors to obtain insights into ecological speciation and species divergence in this endemic rare peony. RAxML analysis indicated that the topological trees recovered from three different data sets were identical, where P. rockii subsp. rockii and P. rockii subsp. taibaishanica clustered together, and molecular dating analyses suggested that the two subspecies diverged 0.83 million years ago. In addition, ecological niche modeling showed that the predicted suitable distribution areas for P. rockii subsp. rockii and P. rockii subsp. taibaishanica differed considerably, although the predicted core distribution areas were similar, where the population contracted in the last interglacial and expanded in the last glacial maximum. Under the emissions scenarios for the 2050s and 2070s, the suitable distribution areas were predicted to contract significantly, where the migration routes of the two subspecies tended to migrate toward high latitudes and elevations, thereby suggesting strong responses of the distributions of the two subspecies to climate change. These findings combined with the phylogeographic relationships provide comprehensive insights into niche variation and differentiation in this endemic rare peony, and they highlight the importance of geological and climatic changes for species divergence and changes in the population geographic patterns of rare and endangered medicinal plants in East Asia.

A novel magnetic metal-organic framework absorbent for rapid detection of aflatoxins B1B2G1G2 in rice by HPLC-MS/MS.

In this study, a core-shell-structured magnetic metal-organic framework (MMOF) composite material (Fe3O4@UiO-66-NH2) was synthesized by the solvothermal method. It was employed as a new absorbent in combination with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the simultaneous detection of four aflatoxins (AFs) in rice. This method could shorten the pre-processing time by exploiting the advantageous characteristics of magnetic cores. The impurity was removed quickly. The effects of extraction solution, extraction time, adsorbent types, and amount of adsorbent on the extraction rate of target compounds were optimized. Under optimized conditions, AFs were validated and showed a good linear relationship within the 0.375-20 µg kg-1 concentration range (r2 > 0.9992). The limit of detection (LOD) was 0.0188-0.1250 µg kg-1 and the limit of quantification (LOQ) was 0.0375-0.3750 µg kg-1. At three spiking levels (0.375, 2, and 10 µg kg-1), the average recovery values for the four AFs ranged from 85.1% to 111.0%. The relative standard deviation ranged from 3.4% to 7.7%. The new method proved to be simple, fast, efficient, and suitable for the determination of AFs in rice samples.

Distributional Response of the Rare and Endangered Tree Species Abies chensiensis to Climate Change in East Asia.

Globally, increasing temperatures due to climate change have severely affected natural ecosystems in several regions of the world; however, the impact on the alpine plant may be particularly profound, further raising the risk of extinction for rare and endangered alpine plants. To identify how alpine species have responded to past climate change and to predict the potential geographic distribution of species under future climate change, we investigated the distribution records of A. chensiensis, an endangered alpine plant in the Qinling Mountains listed in the Red List. In this study, the optimized MaxEnt model was used to analyse the key environmental variables related to the distribution of A. chensiensis based on 93 wild distribution records and six environmental variables. The potential distribution areas of A. chensiensis in the last interglacial (LIG), the last glacial maximum (LGM), the current period, and the 2050s and 2070s were simulated. Our results showed that temperature is critical to the distribution of A. chensiensis, with the mean temperature of the coldest quarter being the most important climatic factor affecting the distribution of this species. In addition, ecological niche modeling analysis showed that the A. chensiensis distribution area in the last interglacial experiencing population expansion and, during the last glacial maximum occurring, a population contraction. Under the emission scenarios in the 2050s and 2070s, the suitable distribution area would contract significantly, and the migration routes of the centroids tended to migrate toward the southern high-altitude mountains, suggesting a strong response from the A. chensiensis distribution to climate change. Collectively, the results of this study provide a comprehensive and multidimensional perspective on the geographic distribution pattern and history of population dynamics for the endemic, rare, and endangered species, A. chensiensis, and it underscores the significant impact of geological and climatic changes on the geographic pattern of alpine species populations.

A Phylogenetically Informed Comparison of GH1 Hydrolases between Arabidopsis and Rice Response to Stressors.

Glycoside hydrolases Family 1 (GH1) comprises enzymes that can hydrolyze ß-O-glycosidic bond from a carbohydrate moiety. The plant GH1 hydrolases participate in a number of developmental processes and stress responses, including cell wall modification, plant hormone activation or deactivation and herbivore resistance. A large number of members has been observed in this family, suggesting their potential redundant functions in various biological processes. In this study, we have used 304 sequences of plant GH1 hydrolases to study the evolution of this gene family in plant lineage. Gene duplication was found to be a common phenomenon in this gene family. Although many members of GH1 hydrolases showed a high degree of similarity in Arabidopsis and rice, they showed substantial tissue specificity and differential responses to various stress treatments. This differential regulation implies each enzyme may play a distinct role in plants. Furthermore, some of salt-responsive Arabidopsis GH1 hydrolases were selected to test their genetic involvement in salt responses. The knockout mutants of AtBGLU1 and AtBGLU19 were observed to be less-sensitive during NaCl treatment in comparison to the wild type seedlings, indicating their participation in salt stress response. In summary, Arabidopsis and rice GH1 glycoside hydrolases showed distinct features in their evolutionary path, transcriptional regulation and genetic functions.

Stereoselective excretion and first-pass metabolism of clausenamide enantiomers.

Stereoselective differences in pharmacokinetics between clausenamide (CLA) enantiomers have been found after intravenous and oral administration of each enantiomer to rats. The differences could be associated with excretion and first-pass metabolism of two enantiomers. The data from this study demonstrated that (-)CLA was mainly excreted in feces with 13.9% of dose, whereas (+)CLA in bile with 17.2%. A large portion of CLA enantiomers could be transformed into hydroxyl metabolites. In the in vitro metabolic system using rat liver microsomes, it was found that (-)CLA was cleared more than its antipode with peak height ratios [(+)/(-)] from 1.0 to 1.8 at the corresponding substrate concentrations from 0.25 to 2mM. Further study in rabbits showed that two enantiomers underwent an intermediate degree of first-pass metabolism. (-)CLA had lower concentrations and AUC0-8h in the portal vein and heart than those of (+)CLA with rates of hepatic extraction 64.7% for (-)-isomer and 50.8% for (+)-isomer, and intrinsic metabolic clearances of (-) and (+)CLA being 186.3 and 107.2 (l/h), respectively. The first-pass metabolism was involved in CYP3A enzymes in the gut and liver, and different levels of CYP3A1 expression induced by (-)CLA or (+)CLA. Immunohistochemical analyses revealed that (-)-isomer significantly increased the expression of CYP3A1, while (+)-isomer had no obvious effects on it. Taken together, the results provided new evidence that stereoselective pharmacokinetics of CLA enantiomers could be resulted from their stereoselective excretion, first-pass metabolism and induction to metabolizing enzymes, which might be important in understanding the clinic pharmacology of active eutomer, (-)CLA, for treatment of Alzheimer's disease.