Simultaneous determination of 18 steroids in the hypothalamic pituitary gonadal axis based on UPLC-MS/MS with multimode ionization.

To objectively quantify changes in steroid hormones in organisms caused by adverse environmental loads, we developed a simple and sensitive UPLC-MS/MS (ultra-performance liquid chromatography triple quadrupole mass spectrometry) method for the simultaneous determination of 18 steroid hormones on the HPG axis. This analytical method was based on liquid extraction and a multimode electrospray and atmospheric pressure chemical ionization (ESCi) source, which was optimized by mass spectrometry, liquid phase and pretreatment for the quantification of cholesterol (CH), aldosterone (A), cortisone (E), hydrocortisone (F), 21-deoxycortisol (21-DF), corticosterone (B), 11-deoxycortisol (11-DF), androstenedione (A2), estradiol (E2), estrone (E1), 2-methoxyestradiol (2-MeE2), 21-hydroxyprogesterone (21-OHP), 17-α hydroxyprogesterone (17α-OHP), testosterone (T), dehydroepiandrosterone (DHEA), progesterone (P4), dihydrotestosterone (DHT), and pregnenolone (P5). The method exhibits linearity in the analyte-concentration range 0.03-1000 µg mL-1 (r2 > 0.99), the spiked recoveries for the concentration range tested are 76.22-113.66%, and the relevant parameters of precision are 7.52-1.14%. Compared to other methods, this new method not only uses a small amount of serum (only 100 µL), but also permits the analysis of the challenging steroid, cholesterol. Furthermore, the method was successfully applied to the determination of steroids in Mus musculus, Carassius auratus, Rana catesbeiana Shaw, and Rana nigromaculata serum samples from randomly selected individuals. Therefore, this method is efficient and a very useful tool for assessing changes in steroid hormones.

Metformin as an Emerging Pollutant in the Aquatic Environment: Occurrence, Analysis, and Toxicity.

The use of human and veterinary drugs has led to the accumulation of pharmaceuticals in various aquatic environments at progressively increasing levels, exhibiting strong ecological risks. Metformin is widely used as a first-line prescription drug for the treatment of type 2 diabetes mellitus as well as a livestock drug. Unlike other drugs, metformin is not metabolized in the body, and almost all of its intake is excreted and released into the aquatic environment via urine and feces, causing adverse effects on aquatic ecosystems. This review provides an overview of the occurrence and detection of metformin in the aquatic environment and its toxic effects on different aquatic organisms (fish, daphnia, rotifers, chlorella). Metformin has been documented in a variety of aqueous environments such as wastewater, surface water, and groundwater as well as drinking water. The wide distribution of metformin in the aqueous environment calls for the development of more accurate detection methods. This paper reviews detection methods for metformin in the aqueous environment and evaluates their advantages and disadvantages. Toxicity studies have shown that metformin can cause adverse reactions in fish, such as oxidative stress, genotoxicity, disruption of intestinal flora, and morphological alterations; it also affects the growth and reproduction of small aquatic organisms. Knowledge gaps in the field of metformin research were assessed, and future research priorities were identified.

High-speed multiparametric imaging through off-resonance tapping AFM with active probe.

Off-resonance tapping (ORT) mode of atomic force microscopy (AFM), based on force-distance curve, is widely concerned due to its advantages of weak tip-sample interaction and concurrent quantitative property mapping. However, the ORT-AFM still has the disadvantage of slow scan speed caused by low modulation frequency. In this paper, we overcome this disadvantage by introducing active probe method. With active probe, the cantilever was directly actuated with the induced strain after applying voltage in the piezoceramic film. In this way, the modulation frequency could be increased to more than an order of magnitude faster than that of traditional ORT, thus improving the scan rate. We demonstrated high-speed multiparametric imaging with the active probe method in ORT-AFM.

Effects of chronic exposure to the fungicide vinclozolin on gut microbiota community in an aquatic turtle.

Environmental issues associated with the widespread use of agricultural chemicals are being seriously concerned. Of them, toxicological impacts of fungicides in aquatic organisms are often overlooked. Here, soft-shelled turtle (Pelodiscus sinensis) hatchlings were exposed to different concentrations of vinclozolin (0, 5, 50, 500 and 5000 µg/L) for 60 days to investigate the impact of fungicide exposure on their gut microbial composition and diversity. Vinclozolin exposure significantly affected the composition of the gut microbiota in hatchling turtles. Unexpectedly, gut bacterial diversity and richness of vinclozolin-exposed turtles (but not for the 5000 µg/L-exposed group) were relatively higher than control ones. At the phylum level, the abundance of Firmicutes was decreased, while that of Proteobacteria was increased in high-concentration groups. At the genus level, some bacterial genera including Cellulosilyticum, Romboutsia and Clostridium_sensu_stricto, were significantly changed after vinclozolin exposure; and some uniquely observed in high-concentration groups. Gene function predictions showed that genes related to amino acid metabolism were less abundant, while those related to energy metabolism more abundant in high-concentration groups. The prevalence of some pathogens inevitably affected gut health status of vinclozolin-exposed turtles. Such gut microbiota dysbiosis might be potentially linked with hepatic metabolite changes induced by vinclozolin exposure.

Development of a multi-functional multi-probe atomic force microscope system with optical beam deflection method.

We developed a multi-probe atomic force microscope (MP-AFM) system with up to four probes and realized various functions such as topography mapping, probing electrical property, and local temperature measurement. Each probe mounted on the corresponding probe scanner was controlled independently, and the system employed the optical beam deflection method to measure the deflection of each cantilever. A high-performance MP-AFM system with a compact optical design and rigid actuators was finally established. We demonstrated AFM high-resolution imaging in air and performed four-probe imaging in parallel and multi-functional characterization with the MP-AFM system.