Leaf ecological stoichiometry and anatomical structural adaptation mechanisms of Quercus sect. Heterobalanus in southeastern Qinghai-Tibet Plateau.

BACKGROUND: With the dramatic uplift of the Qinghai-Tibet Plateau (QTP) and the increase in altitude in the Pliocene, the environment became dry and cold, thermophilous plants that originally inhabited ancient subtropical forest essentially disappeared. However, Quercus sect. Heterobalanus (QSH) have gradually become dominant or constructive species distributed on harsh sites in the Hengduan Mountains range in southeastern QTP, Southwest China. Ecological stoichiometry reveals the survival strategies plants adopt to adapt to changing environment by quantifying the proportions and relationships of elements in plants. Simultaneously, as the most sensitive organs of plants to their environment, the structure of leaves reflects of the long-term adaptability of plants to their surrounding environments. Therefore, ecological adaptation mechanisms related to ecological stoichiometry and leaf anatomical structure of QSH were explored. In this study, stoichiometric characteristics were determined by measuring leaf carbon (C), nitrogen (N), and phosphorus (P) contents, and morphological adaptations were determined by examining leaf anatomical traits with microscopy. RESULTS: Different QSH life forms and species had different nutrient allocation strategies. Leaves of QSH plants had higher C and P and lower N contents and higher N and lower P utilization efficiencies. According to an N: P ratio threshold, the growth of QSH species was limited by N, except that of Q. aquifolioides and Q. longispica, which was limited by both N and P. Although stoichiometric homeostasis of C, N, and P and C: N, C: P, and N: P ratios differed slightly across life forms and species, the overall degree of homeostasis was strong, with strictly homeostatic, homeostatic, and weakly homeostatic regulation. In addition, QSH leaves had compound epidermis, thick cuticle, developed palisade tissue and spongy tissue. However, leaves were relatively thin overall, possibly due to leaf leathering and lignification, which is strategy to resist stress from UV radiation, drought, and frost. Furthermore, contents of C, N, and P and stoichiometric ratios were significantly correlated with leaf anatomical traits. CONCLUSIONS: QSH adapt to the plateau environment by adjusting the content and utilization efficiencies of C, N, and P elements. Strong stoichiometric homeostasis of QSH was likely a strategy to mitigate nutrient limitation. The unique leaf structure of the compound epidermis, thick cuticle, well-developed palisade tissue and spongy tissue is another adaptive mechanism for QSH to survive in the plateau environment. The anatomical adaptations and nutrient utilization strategies of QSH may have coevolved during long-term succession over millions of years.

Exploring the Application Potential of Aquaculture Sewage Treatment of Pseudomonas chengduensis Strain WD211 Based on Its Complete Genome.

Pseudomonas chengduensis is a new species of Pseudomonas discovered in 2014, and currently, there is a scarcity of research on this bacterium. The P. chengduensis strain WD211 was isolated from a fish pond. This study investigated the purification capability and environmental adaptability of strain WD211 in wastewater and described the basic features and functional genes of its complete genome. According to the results, the sewage treated with strain WD211 showed a decrease in concentration of 18.12% in total nitrogen, 89.39% in NH4+, 62.16% in NO3-, 79.97% in total phosphorus, and 71.41% in COD after 24 h. Strain WD211 is able to survive in a pH range of 6-11. It shows resistance to 7% sodium chloride and different types of antibiotics. Genomic analysis showed that strain WD211 may remove nitrogen and phosphorus through the metabolic pathway of nitrogen assimilation and phosphorus accumulation, and that it can promote organic decomposition through oxygenase. Strain WD211 possesses genes for producing betaine, trehalose, and sodium ion transport, which provide it with salt tolerance. It also has genes for antibiotic efflux and multiple oxidases, which give it antibiotic resistance. This study contributes to the understanding of the sewage treatment ability and potential applications of P. chengduensis.

Microplastics alter nitrous oxide production and pathways through affecting microbiome in estuarine sediments.

Increasing microplastics (MPs) pollution in estuaries profoundly impacts microbial ecosystems and biogeochemical processes. Nitrous oxide (N2O), a powerful greenhouse gas, is an important intermediate product of microbial nitrogen cycling. However, how MPs regulate N2O production and its pathways remain poorly understood. Here, impacts of traditional petroleum-based and emerging biodegradable MPs on microbial N2O production and its pathways were studied through dual-isotope (15N-18O) labeling technique and molecular methods. Results indicated that both traditional petroleum-based and emerging biodegradable MPs promoted sedimentary N2O production, whereas pathways varied. Biodegradable polylactic acid (PLA) MPs displayed greater promotion of N2O production than petroleum-based MPs, polyvinyl chloride (PVC) and polyethylene (PE), of which PLA promoted through nitrifier nitrification (NN) and heterotrophic denitrification (HD), PE through nitrifier denitrification and HD, and PVC through NN. By combining the analysis of N2O production rates with sediment chemical and microbiological properties, we demonstrated that the enrichment of nitrifying and denitrifying bacteria, as well as related functional genes directly and/or indirectly increased N2O production primarily by interacting with carbon and nitrogen substrates. Different response of nitrogen cycling microbes to MPs led to the difference in N2O increase pathways, of which nitrifying bacteria significantly enriched in all MPs treatments due to the niches provided by MPs. However, part of denitrifying bacteria significantly enriched in treatments containing PLA and PE MPs, which may serve as organic carbon substrates. This work highlights that the presence of MPs can promote sedimentary N2O production, and the emerging biodegradable MPs represented by PLA may have a greater potential to enhance estuarine N2O emissions and accelerate global climate change.

Optimised extraction of Erythronium sibiricum bulb polysaccharides and evaluation of their bioactivities.

In this study, the extraction of Erythronium sibiricum bulb polysaccharides (ESBP) through hot water decoction was optimised using response surface methodology (RSM) and a three-level, four-factor Box-Behnken design. The optimum extraction conditions were as follows: extraction time of 4.28h, extraction temperature of 90°C, ratio of liquid to raw material of 37 mL/g and extraction cycle number of three. The experimental yield (37.25%±0.17%) agreed with the predicted value of the RSM model (37.465%). Preliminary ESBP characterisation was conducted through physicochemical analysis. Biological activity test results showed that ESBP exhibited antioxidant activities and excellent anti-inflammatory and analgesic activities, indicating its potential as an anti-inflammatory and analgesic agent.

Sorafenib suppresses the rapid progress of hepatocellular carcinoma after insufficient radiofrequency ablation therapy: an experiment in vivo.

BACKGROUND: Radiofrequency ablation (RFA) is a widely applied treatment for hepatocellular carcinoma (HCC), but insufficient RFA can promote rapid progression of the residual tumor through the hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor A (VEGFA) pathway. Although sorafenib has been successfully applied to advanced HCC, the use of sorafenib in residual tumor cells after RFA has rarely been tested. PURPOSE: To evaluate the potential role of sorafenib as an adjunct to RFA to reduce the recurrence rate after insufficient RFA. MATERIAL AND METHODS: Xenograft tumors of SMMC 7721 were created by subcutaneously inoculating nude mice with hepatoma cells (5 × 10(6) cells per mouse). Fourteen days after inoculation, all mice were divided into three groups (control group [sham puncture], RFA group, and RFA combined with sorafenib treatment group) with six mice in each group. Each group was given a different treatment procedure. After treatment, the volume of the tumors was calculated from the resected specimens. The mRNA and protein expression of HIF-1α and VEGFA was quantified by real-time PCR and immunohistochemistry analysis. The micro-vessel density (MVD) was determined by CD34 immunohistochemistry. RESULTS: Real-time PCR and immunohistochemistry analysis showed that, compared to the RFA group, HIF-1α and VEGFA expression were significantly decreased in the group that received RFA combined with sorafenib treatment (P < 0.05). By comparing the control group with the RFA group, we found that insufficient RFA promoted HIF-1α and VEGFA expression (P < 0.05). Similar results were obtained for MVD expression. Additionally, the combination of RFA with sorafenib therapy resulted in a synergistic reduction in tumor growth compared to insufficient RFA and sham puncture (P < 0.05). CONCLUSION: Sorafenib was able to inhibit the expression of HIF-1α and VEGFA, and sorafenib was able to increase time to recurrence when used as an adjunct to RFA.