Transcriptomic analysis revealing the molecular response to arsenic stress in desert Eremostachys moluccelloides Bunge.

The saline, alkaline environment of arid soils is conducive to the diffusion of the metalloid arsenic (As). Desert plants in this area are of great ecological importance and practical value. However, there are few studies on the mechanism of arsenic action in desert plants. Therefore, in this study, Eremostachys moluccelloides Bunge was treated with different concentrations of As2O5 [As(V)] to analyze the physiological, biochemical, and transcriptomic changes of its roots and leaves and to explore the molecular mechanism of its response to As(Ⅴ) stress. The activities of catalase, superoxidase, peroxidase, and the contents of malondialdehyde and proline in roots and leaves first increased and then decreased under the As(Ⅴ) stress of different concentrations. The content of As was higher in roots than in leaves, and the As content was positively correlated with As(Ⅴ) stress concentration. In the differentially expressed gene analysis, the key enzymes of the oxidative stress response in roots and leaves were significantly enriched in the GO classification. In the KEGG pathway, genes related to the abscisic acid signal transduction pathway were co-enriched and up-regulated in roots and leaves. The related genes in the phenylpropanoid biosynthesis pathway were significantly enriched and down-regulated only in roots. In addition, the transcription factors NAC, HB-HD-ZIP, and NF-Y were up-regulated in roots and leaves. These results suggest that the higher the As(V) stress concentration, the more As is taken up by roots and leaves of E. molucelloides Bunge. In addition to causing greater oxidative damage, this may interfere with the production of secondary metabolites. Moreover, it may improve As(V) tolerance by regulating abscisic acid and transcription factors. The results will deepen our understanding of the molecular mechanism of As(Ⅴ) response in E. moluccelloides Bunge, lay the foundation for developing and applying desert plants, and provide new ideas for the phytoremediation of As pollution in arid areas.

Suspended particulate matter-associated environmental corticosteroids in the Pearl River, China: Occurrence, distribution, and partitioning.

Suspended particulate matter (SPM) plays an important role in the geochemical behavior and fate of organic micropollutants in aquatic environments. However, the presence of trace emerging endocrine disruptors such as environmental corticosteroids (ECs) in SPM is less well understood. This study focused on the occurrence, distribution, and partitioning of SPM-associated ECs in the Pearl River system, China. Ubiquitous particulate ECs were found in the surface water of the rivers at average concentrations (dry weight) between 0.46 ng/g (flumethasone) and 8.83 ng/g (clobetasone butyrate). The total EC (∑ECs) concentrations of the 24 selected target compounds varied from <1.03 ng/g to 62.3 ng/g, with an average and median of 17.6 ng/g and 13.7 ng/g, respectively. Higher SPM-bound EC levels were commonly observed in winter (dry season), and spatially, their relatively high contamination in urban tributary networks decreased while flowing to mainstreams and then gradually attenuated from upstream to the estuary. Despite the approximately 90 % mass distribution of ∑ECs in the aqueous phase, approximately 50 % of their effect burden was derived from the suspended particulate fractions. For the first time, in situ SPM-water partitioning coefficients (Kp) and their organic carbon-normalized ones (Koc) of ECs were determined in surface waters, and a field-derived preliminary linear equation was proposed to estimate Koc for ECs using basic physicochemical parameters n-octanol/water partitioning coefficient (Kow), which is of importance with regard to the assessment of transport, fate, and risk of these emerging hazardous chemicals. Furthermore, the significant logKoc-logKow relationship for ECs reveals that nonspecific hydrophobic partitioning is a major association mechanism between SPM and ECs. Moreover, hydrogen bonding is suggested to be a prevailing specific binding mechanism and provides more contribution to nonhydrophobic interactions between ECs and particulate organic matter than environmental estrogens.

Preparation of fish decalcified bone matrix and its bone repair effect in rats.

Decalcified bone matrix has great potential and application prospects in the repair of bone defects due to its good biocompatibility and osteogenic activity. In order to verify whether fish decalcified bone matrix (FDBM) has similar structure and efficacy, this study used the principle of HCl decalcification to prepare the FDBM by using fresh halibut bone as the raw material, and then degreasing, decalcifying, dehydrating and freeze-drying it. Its physicochemical properties were analyzed by scanning electron microscopy and other methods, and then its biocompatibility was tested by in vitro and in vivo experiments. At the same time, an animal model of femoral defect in rats was established, and commercially available bovine decalcified bone matrix (BDBM) was used as the control group, and the area of femoral defect in rats was filled with the two materials respectively. The changes in the implant material and the repair of the defect area were observed by various aspects such as imaging and histology, and its osteoinductive repair capacity and degradation properties were studied. The experiments showed that the FDBM is a form of biomaterial with high bone repair capacity and lower economic cost than other related materials such as bovine decalcified bone matrix. FDBM is simpler to extract and the raw materials are more abundant, which can greatly improve the utilization of marine resources. Our results show that FDBM not only has a good repair effect on bone defects, but also has good physicochemical properties, biosafety and cell adhesion, and is a promising medical biomaterial for the treatment of bone defects, which can basically meet the clinical requirements for bone tissue repair engineering materials.

Screening and validating of endogenous reference genes in Chlorella sp. TLD 6B under abiotic stress.

Chlorella sp. TLD 6B, a microalgae growing in the Taklamakan Desert, Xinjiang of China, is a good model material for studying the physiological and environmental adaptation mechanisms of plants in their arid habitats, as its adaptation to the harsh desert environment has led to its strong resistance. However, when using real-time quantitative polymerase chain reaction (RT-qPCR) to analyze the gene expression of this algae under abiotic stress, it is essential to find the suitable endogenous reference genes so to obtain reliable results. This study assessed the expression stability of 9 endogenous reference genes of Chlorella sp. TLD 6B under four abiotic stresses (drought, salt, cold and heat). These genes were selected based on the analysis results calculated by the three algorithmic procedures of geNorm, NormFinder, and BestKeeper, which were ranked by refinder. Our research showed that 18S and GTP under drought stress, 18S and IDH under salt stress, CYP and 18S under cold stress, GTP and IDH under heat stress were the most stable endogenous reference genes. Moreover, UBC and 18S were the most suitable endogenous reference gene combinations for all samples. In contrast, GAPDH and α-TUB were the two least stable endogenous reference genes in all experimental samples. Additionally, the selected genes have been verified to be durable and reliable by detecting POD and PXG3 genes using above endogenous reference genes. The identification of reliable endogenous reference genes guarantees more accurate RT-qPCR quantification for Chlorella sp. TLD 6B, facilitating functional genomics studies of deserts Chlorella as well as the mining of resistance genes.

[Simultaneous determination of 24 corticosteroids in sediments based on ultrasonic extraction, solid-phase extraction, liquid chromatography, and tandem mass spectrometry].

Corticosteroids (CSs) are widely used to treat various inflammatory and immune diseases in humans and animals, such as arthritis and lupus. Thus far, CSs have been frequently detected in diverse pollution sources, such as in the influent and effluent of traditional wastewater treatment plants, livestock farms, and aquaculture. Owing to incomplete removal or limited treatment, CSs can enter the water environment and eventually be adsorbed in the sediment. Due to hydrodynamic effects, CSs can re-enter the surface water through the resuspension of sediments, and pose a hazard to the ecosystem and human health via the enrichment of aquatic organisms and transmission through the food chain. Therefore, trace analysis of CSs in sediments is significant for exploring their prevalence and behavior in multiple environments. However, existing research mainly focuses on the determination of glucocorticoids in water samples, and studies on the systematic quantitative analysis of CSs in environmental solid samples with more complex matrices are scarce. Moreover, majority of previous investigations focused on a limited number of glucocorticoids, making it important to widen the range of target compounds to be studied, including mineralocorticoids. In this study, the main factors which could influence the accuracy and sensitivity in the determination of 24 target CSs were systematically optimized in the sample pretreatment and instrument analysis. A novel method based on ultrasonic extraction coupled with solid phase extraction (SPE) for sample pretreatment was developed for the simultaneous determination of the 24 CSs in sediments using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sediment sample was ground to homogenize the particle sizes after freeze-drying. The analytes from 2.0 g of the sample were ultrasonicated and extracted with methanol-acetone (1∶1, v/v). After concentrating and diluting each extract, SPE was performed. The water sample was extracted and purified using hydrophile-lipophile balance (HLB) cartridges, following which the extract was further purified with LC-NH2 cartridges. The extracts were concentrated using a rotary evaporator, dried under a gentle stream of nitrogen, and re-dissolved in methanol for instrumental analysis. Chromatographic separation was conducted on an Agilent ZORBAX Eclipse Plus C8 column (100 mm×2.1 mm, 1.8 µm), with a column flow rate of 0.3 mL/min and a gradient of mobile phases A (water with 0.1% acetic acid) and B (acetonitrile). The column temperature was set to 30 ℃ and the injection volume was fixed at 5 µL. Electrospray ionization MS in the dynamic multiple reaction monitoring (DMRM) and selected ion monitoring (SIM) modes were performed in the positive mode for the qualitative and quantitative analysis of the target compounds. Quantitation of the target compounds was carried out using the internal standard method. The effects of different extraction solvents, purification conditions, and MS conditions on the recoveries of the target compounds were investigated. The limits of detection (LODs) (S/N≥3) and limits of quantification (LOQs) (S/N≥10) of all 24 compounds were in the ranges of 0.14-1.25 µg/kg and 0.26-2.26 µg/kg, respectively. The correlation coefficients of linear calibration curves were higher than 0.995 in the range of 1.0-100 µg/L. The recoveries of the 24 CSs at 5, 20, and 50 µg/kg spiked levels ranged from 64.9% to 125.1% with relative standard deviations of 0.4%-12.6% (n=5). The developed method was applied to analyze the CSs in three sediment samples from the rivers of the Pearl River Delta. In all, 11 target compounds were detected in these samples, with contents in the range of 1.25-29.38 µg/kg. The characteristic of this method is efficient, sensitive, reliable, and suitable for the trace determination of varieties of natural and synthesized CSs in environmental sediments.

Metachronous small bowel adenocarcinoma after rectal adenocarcinoma: A case report.

RATIONALE: Small bowel adenocarcinoma (SBA), an uncommon gastrointestinal malignant tumor, is difficult to diagnose at an early stage because of its non-specific disease presentation. Metachronous SBA is a special type of SBA that is rarely reported. We herein report a case of metachronous primary SBA following resection of rectal adenocarcinoma. PATIENT CONCERNS: A 65-year-old man presented to our hospital after having experienced recurrent bowel obstruction for 6 months. He had undergone a Dixon operation 30 months previously followed by adjuvant chemotherapy with capecitabine plus oxaliplatin. DIAGNOSIS: Abdominal computed tomography showed thickened bowel walls in the right lower abdomen, and the patient was initially misdiagnosed with intestinal adhesion. After the operation, he was diagnosed with primary SBA (T3N0M0, stage IIA). INTERVENTIONS: Treatment with a transnasal ileus tube was ineffective. Therefore, we performed small intestinal segmental resection and side-to-side anastomosis through open surgery. OUTCOMES: The patient completed all postoperative adjuvant chemotherapy, and posttreatment surveillance revealed no further abnormalities. LESSONS: This case suggests that patients with colorectal adenocarcinoma may have an increased risk of metachronous SBA. Corresponding symptoms in high-risk patients should raise clinicians' suspicion for SBA, and further detailed examinations are imperative. Early screening for SBA may help to improve the patients' prognosis.

Spatiotemporal distribution, source apportionment, and ecological risk of corticosteroids in the urbanized river system of Guangzhou, China.

We investigated the occurrence and distribution of 24 selected corticosteroids (CSs) in the surface water of the Zhujiang River (ZR) system in Guangzhou, a highly urbanized river system receiving both treated and untreated municipal wastewater effluents. Twenty-two and sixteen CSs were detected in the tributaries and the main stream of the ZR system, and their concentrations ranged from less than the method quantification limit (fluticasone propionate) to 94 ng/L (clobetasone butyrate) and from 0.24 ng/L (cortisol) to 7.2 ng/L (clobetasone butyrate), respectively. We observed higher total CSs (∑CSs) concentrations in the tributaries (11-396 ng/L) relative to the main stream (5.5-33 ng/L) due to their proximity to densely populated residential areas. ∑CSs concentrations in the dry season were generally higher than those in the wet season due to low dilution from decreased river discharge. Principal component analysis and multiple linear regression analysis identified untreated domestic sewage to be the dominant source of CSs (t2, contribution rate: 42.7%) in the urban rivers. Additional source contributions were from naturally attenuated treated and/or raw sewage (t1, 21.5%) and effluents from wastewater treatment plants (t3, 26.7%). CSs contribution was dominated by t2 in the dry season, and the contributions from t1, t2, and t3 showed no significant difference in the wet season. Risk assessment inferred that the ZR system is at medium to high ecological risk from CSs and is therefore a potential threat to the health of aquatic ecosystems. To prevent CSs pollution, our results demonstrate the need to develop effective control strategies to minimize the discharge of untreated waste to nearby rivers and to improve the capacity of wastewater treatment plants in Guangzhou. Further, we demonstrate that the concentrations of cortisone and fludrocortisone acetate are effective chemical indicators to estimate the level of natural and synthetic CSs contamination in urban rivers.

Occurrence, distribution, and potential risks of environmental corticosteroids in surface waters from the Pearl River Delta, South China.

The occurrence, spatiotemporal distribution, and potential risks of 21 glucocorticoids (GCs) and 3 mineralocorticoids (MCs) in four rivers were studied by investigating the surface waters from the Pearl River Delta (PRD), South China. These environmental corticosteroids (ECs) were commonly present in the river surface waters with average concentrations varying from <0.17 ng/L for fluticasone propionate to 5.6 ng/L for clobetasone butyrate; and cortisone had the highest concentration, 32.9 ng/L. The total ECs ranged in concentration from undetectable to 83.3 ng/L, with a mean and median of 8.1 ng/L and 4.8 ng/L, respectively. Spatially the total EC concentration levels in the Pearl River system occurred in the following order: Zhujiang River (ZR) > Dongjiang River (DR) > Shiziyang waterway (SW) > Beijiang River (BR). These levels generally demonstrated a trend of increasing from upstream to midstream or downstream then attenuating toward the estuary. Considerable seasonal variations in the ECs differed among rivers. Higher ECs concentrations in winter were mostly found in the ZR, whereas lower levels were found in the DR. Moreover, the temporal variations of the ECs were marginal in the BR and SW. These spatiotemporal distributions of the ECs might have been simultaneously influenced by pollution sources derived from anthropogenic activities and river hydrologic conditions. Correlation analyses indicated that dissolved organic carbon (DOC) could play a key role in the occurrence and distribution of ECs in an aquatic environment. Risk assessment demonstrated that the occurrence of ECs might have posed medium to high risk to aquatic organisms in the Pearl River.