The nitrogen-sulfur ratio of acid rain modulates the leaf- and root-mediated co-allelopathy of Solidago canadensis.

The majority of allelopathic studies on invasive plants have focused primarily on their leaf-mediated allelopathy, with relatively little attention paid to their root-mediated allelopathy, especially co-allelopathy mediated by both leaves and roots. It is conceivable that the diversified composition of acid rain may influence the allelopathy of invasive plants. This study aimed to evaluate the leaf and root-mediated co-allelopathy of the invasive plant Solidago canadensis L. under acid rain with different nitrogen-sulfur ratios (N/S) on Lactuca sativa L. via a hydroponic incubation. The root-mediated allelopathy of S. canadensis was found to be more pronounced than the leaf-mediated allelopathy of S. canadensis with nitric acid at pH 4.5, but the leaf-mediated allelopathy of S. canadensis was observed to be more pronounced than the root-mediated allelopathy of S. canadensis with sulfuric-rich acid at pH 4.5. The leaf and root-mediated co-allelopathy of S. canadensis was more pronounced than that of either part alone with sulfuric acid at pH 5.6 and nitric acid at pH 4.5, but not with nitric-rich acid at pH 4.5 and sulfuric-rich acid at pH 4.5. Sulfuric acid and sulfuric-rich acid with stronger acidity intensified the leaf-mediated allelopathy of S. canadensis. Nitric acid and nitric-rich acid attenuated the leaf-mediated allelopathy of S. canadensis, and most types of acid rain (especially nitric acid and nitric-rich acid) also attenuated the root-mediated allelopathy of S. canadensis and the leaf and root-mediated co-allelopathy of S. canadensis. Sulfuric acid and sulfuric-rich acid produced a more pronounced effect than nitric acid and nitric-rich acid. Hence, the N/S ratio of acid rain influenced the allelopathy of S. canadensis under acid rain with multiple N/S ratios.

The Invasive Plant Amaranthus spinosus L. Exhibits a Stronger Resistance to Drought than the Native Plant A. tricolor L. under Co-Cultivation Conditions When Treated with Light Drought.

Drought may facilitate the invasion process of invasive plants, mainly because invasive plants can obtain a stronger growth competitiveness than native plants under drought. It is therefore imperative to illuminate the mechanisms underlying the successful invasion of invasive plants under drought, with a particular focus on the differences in the resistance of invasive and native plants to drought. This study aimed to elucidate the differences in the resistance between the invasive plant Amaranthus spinosus L. and the native plant A. tricolor L. to drought under a gradient of drought. The resistance of co-cultivated A. spinosus to drought was significantly higher than that of co-cultivated A. tricolor under light drought. Hence, A. spinosus may obtain a stronger competitive advantage than A. spinosus under co-cultivation conditions when treated with light drought. The resistance of the two plants to drought may be predominantly influenced by their height and biomass. This present study also defines a method for evaluating the stress resistance of a given plant species to stress by calculating the stress resistance index. This present study offers a robust theoretical foundation for determining the stress resistance of a given plant species and the environmental management of A. spinosus under drought.

Does Bidens pilosa L. Affect Carbon and Nitrogen Contents, Enzymatic Activities, and Bacterial Communities in Soil Treated with Different Forms of Nitrogen Deposition?

The deposition of nitrogen in soil may be influenced by the presence of different nitrogen components, which may affect the accessibility of soil nitrogen and invasive plant-soil microbe interactions. This, in turn, may alter the success of invasive plants. This study aimed to clarify the influences of the invasive plant Bidens pilosa L. on the physicochemical properties, carbon and nitrogen contents, enzymatic activities, and bacterial communities in soil in comparison to the native plant Pterocypsela laciniata (Houtt.) Shih treated with simulated nitrogen deposition at 5 g nitrogen m-2 yr-1 in four forms (nitrate, ammonium, urea, and mixed nitrogen). Monocultural B. pilosa resulted in a notable increase in soil pH but a substantial decrease in the moisture, electrical conductivity, ammonium content, and the activities of polyphenol oxidase, ß-xylosidase, FDA hydrolase, and sucrase in soil in comparison to the control. Co-cultivating B. pilosa and P. laciniata resulted in a notable increase in total soil organic carbon content in comparison to the control. Monocultural B. pilosa resulted in a notable decrease in soil bacterial alpha diversity in comparison to monocultural P. laciniata. Soil FDA hydrolase activity and soil bacterial alpha diversity, especially the indices of Shannon's diversity, Simpson's dominance, and Pielou's evenness, exhibited a notable decline under co-cultivated B. pilosa and P. laciniata treated with nitrate in comparison to those treated with ammonium, urea, and mixed nitrogen.

Bone regeneration materials and their application over 20 years: A bibliometric study and systematic review.

Bone regeneration materials (BRMs) bring us new sights into the clinical management bone defects. With advances in BRMs technologies, new strategies are emerging to promote bone regeneration. The aim of this study was to comprehensively assess the existing research and recent progress on BRMs, thus providing useful insights into contemporary research, as well as to explore potential future directions within the scope of bone regeneration therapy. A comprehensive literature review using formal data mining procedures was performed to explore the global trends of selected areas of research for the past 20 years. The study applied bibliometric methods and knowledge visualization techniques to identify and investigate publications based on the publication year (between 2002 and 2021), document type, language, country, institution, author, journal, keywords, and citation number. The most productive countries were China, United States, and Italy. The most prolific journal in the BRM field was Acta Biomaterialia, closely followed by Biomaterials. Moreover, recent investigations have been focused on extracellular matrices (ECMs) (370 publications), hydrogel materials (286 publications), and drug delivery systems (220 publications). Research hotspots related to BRMs and extracellular matrices from 2002 to 2011 were growth factor, bone morphogenetic protein (BMP)-2, and mesenchymal stem cell (MSC), whereas after 2012 were composite scaffolds. Between 2002 and 2011, studies related to BRMs and hydrogels were focused on BMP-2, in vivo, and in vitro investigations, whereas it turned to the exploration of MSCs, mechanical properties, and osteogenic differentiation after 2012. Research hotspots related to BRM and drug delivery were fibroblast growth factor, mesoporous materials, and controlled release during 2002-2011, and electrospinning, antibacterial activity, and in vitro bioactivity after 2012. Overall, composite scaffolds, 3D printing technology, and antibacterial activity were found to have an important intersection within BRM investigations, representing relevant research fields for the future. Taken together, this extensive analysis highlights the existing literature and findings that advance scientific insights into bone tissue engineering and its subsequent applications.

Modified Alginate-Based Hydrogel as a Carrier of the CB2 Agonist JWH133 for Bone Engineering.

Alginate hydrogels have been widely used as excellent scaffold materials for implantation in biological systems because of their good biocompatibility. However, it is difficult to repair bone defects with these materials because of their poor mechanical properties. The aim of the present study was to fabricate a novel degradable alginate/palygorskite (PAL) composite hydrogel with good mechanical properties and investigate its potential for application in bone defect repair. The modified alginate-based hydrogel with increasing PAL content exhibited better mechanical properties than the original alginate hydrogel. In addition, the resulting composite hydrogel was thoroughly characterized by scanning electron microscopy (SEM). With increasing PAL content, the swelling ratio of the hydrogel increased in PBS (pH = 7.4). In vitro cytocompatibility was evaluated using bone marrow-derived mesenchymal stem cells (BMSCs) to confirm that the developed composite hydrogel was cytocompatible after 1, 3, and 7 days. All these results suggest that the developed composite hydrogel has great potential for bone tissue engineering applications. JWH133 is a selective agonist of cannabinoid receptor type 2 (CB2), which exerts dual anti-inflammatory and anti-osteoclastogenic effects. We co-cultured BMSCs with composite hydrogels loaded with JWH133, and analysis of proliferation and osteogenic differentiation indicated that the composite hydrogel loaded with JWH133 may enhance the osteogenic differentiation of rat BMSCs. Furthermore, we found that the composite hydrogel loaded with JWH133 inhibited osteoclast formation and the mRNA expression of osteoclast-specific markers. In summary, the developed composite hydrogel has a high drug-loading capacity, good biocompatibility, and strong potential as a drug carrier for treating osteoporosis by promoting osteoblast and inhibiting osteoclast formation and function.

[Effects of domoic acid on membrane function of primary cultured rat glial cells].

OBJECTIVE: To study the effects of domoic acid (DA) on membrane function of primary cultured rat glial cell. METHODS: After the glial cells were treated with 6.4 x 10(-2), 6.4 x 10(-3) and 6.4 x 10(-4) micromol/L DA for 24 h, the activities of Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase, the membrane fluidity and the permeability were measured to reflect the membrane function. RESULTS: After treatment of DA for 24 h, the activities of Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase were inhibited significantly, the membrane fluidity decreased and the membrane permeability increased. The fluorescence polarization and microviscosity in the low, middle and high dosage treatment groups were 0.0626 +/- 0.0051, 0.0685 +/- 0.0097, 0.0648 +/- 0.0086 and 0.3154 +/- 0.0298, 0.3510 +/- 0.0571, 0.3286 +/- 0.0504 respectively, compared with the control group (0.0481 +/- 0.0069 and 0.2338 +/- 0.0372) (P < 0.01). CONCLUSION: DA has obvious effects on membrane function of rat glial cells and may cause further injury on the cells.

[Toxicity and oxidative stress on rats by hexachlorobenzene].

OBJECTIVE: To study the toxicity on rats by hexachlorobenzene (HCB), and to explore the role of oxidative stress in the mechanism of HCB intoxication. METHODS: SD female rats were fed on a powdered diet containing 0.25 per thousand or 2.00 per thousand HCB for 14 days. The content of malondialdehyde (MDA) and the activity of total-superoxide dismutase (T-SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) in cerebral cortex, hippocampus, liver tissue and serum were determined. Eleven biochemical indicators including alkaline phosphatase (ALP) were surveyed. RESULTS: (1) MDA levels in cerebral cortex, hippocampus, liver and serum of the high dosage group rats and that in hippocampus and serum of the low dosage group were significantly higher than that of the control group. (2) The activity of T-SOD was increased in cerebral cortex and hippocampus of the rats in both groups (P < 0.01), but decreased in the serum of the high dosage group (P < 0.01). (3) The activity of CAT was also increased in the hippocampus of rats in the high dosage group. (4) In cerebral cortex and hippocampus of the rats in the high dosage group and in the hippocampus of the rats in the low dosage group, the activity of GSH-PX was significantly higher compared with the control group. However, in liver of both dosage groups, the activity of GSH-PX was decreased (P < 0.01). (5) The activity of serum alkaline phosphatase of both dosage groups was also decreased, but the contents of both serum albumin and total cholesterol were significantly higher than those of the control group (P < 0.01). CONCLUSION: HCB can induce enhanced lipid peroxidation on SD rats, and the oxidative stress plays an important role in the mechanism of neurotoxicity and hepatotoxicity.