Interguild fungal competition in litter and soil inversely modulate microbial necromass accumulation during Loess Plateau forest succession.

Microbial interactions determine ecosystem carbon (C) and nutrient cycling, yet it remains unclear how interguild fungal interactions modulate microbial residue contribution to soil C pools (SOC) during forest succession. Here, we present a region-wide investigation of the relative dominance of saprophytic versus symbiotic fungi in litter and soil compartments, exploring their linkages to soil microbial residue pools and potential drivers along a chronosequence of secondary Chinese pine (Pinus tabulaeformis) forests on the Loess Plateau. Despite minor changes in C and nitrogen (N) stocks in the litter or soil layers across successional stages, we found significantly lower soil phosphorus (P) stocks, higher ratios of soil C: N, soil N: P and soil C: P but lower ratios of litter C: N and litter C: P in old (>75 years) than young stands (<30 years). Pine stand development altered the saprotroph: symbiotroph ratios of fungal communities to favor the soil symbiotrophs versus the litter saprotrophs. The dominance of saprotrophs in litter is positively related to microbial necromass contribution to SOC, which is negatively related to the dominance of symbiotrophs in soils. Antagonistic interguild fungal competition in litter and soil layers, in conjunction with increased fungal but decreased bacterial necromass contribution to SOC, jointly contribute to unchanged total necromass contribution to SOC with stand development. The saprotroph: symbiotroph ratios in litter and soil layers are mainly driven by soil P stocks and stand parameters (e.g., stand age and slope), respectively, while substrate stoichiometries primarily regulate microbial necromass accumulation and fungal: bacterial necromass ratios. These results provide novel insights into how microbial interactions at local spatial scales modulate temporal changes in SOC pools, with management implications for mitigating regional land degradation.

[Effect of different fertilization treatments on growth,secondary metabolites,and seed yield and quality of Perilla frutescens].

Perilla frutescens,an annual plant in Labiatae family,is grown throughout China and can be used for medicine purposes and as food additives. The present field experiment was carried out to study the effects of different fertilizer treatments on the concentrations and accumulations of antioxidant components,including flavonoids and polyphenols,growth,seed yields and qualities of this plant.The main aim of this study is to provide farmers some advice for improving the yields and qualities of P. frutescens in theory and practice.Five treatments were set up,including a no fertilizer control(CK),chemical fertilizers(CF),organic fertilizers(M),organic fertilizers plus chemical fertilizers at the rates of 1 ∶1 and 1 ∶3 in terms of nitrogen(50 M,25 M). Plant growth parameters were recorded and total flavonoids and polyphenols were determined in three key growth stages of P. frutescens. At the fast growth period,samples of roots,leaves,and stems were collected for determining a total of flavonoids and polyphenols as well as DPPH removal rate of ethanol extracts. Seed yields and qualities were also recorded at harvest. The results showed fertilization enhanced growth and seed yields although no significant difference was observed in growth and seed yields in inorganic-organic fertilizer treatments. The total flavonoids,polyphenols,and DPPH removal rate of ethanol extracts followed the sequence leaves>stems>roots,indicating synthesis of these metabolites in the leaves. DPPH removal rate showed a positive linear correlation with total flavonoid and polyphenol concentrations. In addition,organic-inorganic fertilization significantly increased the numbers of both effective panicles and paniclegrains. Fertilizer treatments had no effect on seed qualities of P. frutescens,while 50 M achieved the highest yield,which increased by 14. 73% compared to CF alone. In general,50 M increased antioxidant components,biomass,and seed yield of P. frutescens,meriting advocate in cultivation.

[Influence of continuous cropping on growth of Artemisia annua and bacterial communities in soil].

In this study, several types of Artemisia annua in soil, including the soil which had not been planted, or planted for one year, or continuously planted for three or five years were collected, in order to study the influences of continuous cropping on the growth of A. annua, content of artemisinin, available nutrient of soil, and bacterial community structure through adopting routine analysis and Illumina MiSeq high-throughput sequencing. The results showed that continuous cropping inhibited significantly the growth of A. annua and reduced leaf biomass, content and yield of artemisinin, with the maximum decreasing amplitude of 30.20%, 7.70% and 35.58% respectively. The content of soil organic matter, available nitrogen, available phosphorus and 16S rRNA sequence number were increased to different extents after continuous cropping of A. annua. According to the results of high-throughput sequencing, 634-812 types of common bacteria belonged to 21 categories were planted in different soil of A. annua with different planting years, which represented that the distribution distance of the point of bacterial community with different years among coordinate system of principal component was relative distant, and community structure had significant changes (P<0.05). As the planting years increased, the abundance of Actinobacteria, Chloroflexi, Gemmatimonadetes decreased in contrast to Proteobacteria, Acidobacteria and Verrucomicrobia. In the top 20 types of predominant bacteria,Nitrospira japonica and Nitrospira disappeared, among which, only Gemmatimonadaceae, Micromonosporaceae, Nitrosomonadaceae, Xanthobacteraceae, and unculture bacterium JG30-KF-AS9 were similar, indicating that the planting and continuous cropping of A. annua selectively inhibited the growth and reproduction of soil bacteria, and influenced the supply and transform of soil nutrient, leading to a poor growth and resulting in reduction of artemisinin content and yield. Therefore, it is necessary to advocate crop rotation in the process of planting A. annua.

Salidroside prevents cognitive impairment induced by chronic cerebral hypoperfusion in rats.

OBJECTIVE: To investigate the effects of salidroside on cognitive dysfunction induced by chronic cerebral hypoperfusion in rats. METHODS: Male Sprague-Dawley rats (n = 36) were divided into three groups (n = 12 per group): sham operation; bilateral permanent occlusion of the common carotid arteries (2-VO); 2-VO + salidroside. Rats received 20 mg/kg per day salidroside or vehicle intraperitoneal injection beginning the day before surgery and continuing until 34 days postoperatively. Cognitive function was evaluated by Morris water maze test and hippocampal long-term potentiation (LTP) measurement. Hippocampal neuronal apoptosis was evaluated via immunofluorescence. RESULTS: Chronic cerebral hypoperfusion caused marked cognitive deficit and LTP inhibition. These effects were largely ameliorated by salidroside administration. Salidroside prevented caspase-3 activation, increased the ratio of Bax/Bcl-2, and reversed hippocampal neuronal loss induced by chronic cerebral hypoperfusion. CONCLUSIONS: Salidroside prevents cognitive deficits caused by chronic cerebral hypoperfusion in rats, and alleviates apoptosis in the hippocampal CA1 area.

[Response of ectomycorrhizal fungi to aluminum stress and low potassium soil].

Soil acidification, aluminum (Al3+) toxicity and nutrient deficiency could be some of the most important reasons for the decline and death of forests in tropical and subtropical areas. Ectomycorrhizal fungi for Al3+ resistance and nutrient mobilization are beneficial for preventing forests against Al3+ toxicity and increasing forest productivity. Therefore, Suillus luteus (SI 13), Pisolithus tinctorius (Pt 715) and Suillus subluteus (Ss 00) were grown in liquid culture medium with soil as the sole K source under Al3+ stress to study the fungal growth, organic acid and proton efflux, and potassium (K) unitization. The result indicated that the fungal growth, organic acid and proton efflux, and nutrient uptake, including nitrogen (N), phosphorus (P) and potassium (K), were regulated by Al3+ concentration in culture solutions. They increased with increasing Al3+ at low concentration and after reaching a peak, they started to decrease. Fungal strain with high resistance to Al3+ also showed higher Al3+ concentration at the peak than those with low ability. Al3+ concentration at the peak of fungal biomass and N uptake by Pt 715 was four folds or twice of Ss 00 and SI 13, respectively. The uptake of P and K and efflux of organic acids and protons by Pt 715 were also higher than Ss 00 and Sl 13. All three fungal strains could utilize structural K in soil minerals and the utilization rate reached 2.10% for Pt 715, 1.43% for Ss 00 and 1.17% for Sl 13, respectively, which could be related to the types and amount of organic acids and protons.

[Effect of fibrous root extract of Coptis chinensis on soil microbes and enzyme activities].

Coptis chinensis is widely used as Chinese medicine herbs and serious soil problems occur after continual cultivation of this medicinal plant. In the preset experiment, fibrous root extract of C. chinensis (REC) was added into soil to study the effect of REC on microbes and enzyme activity in soil. The results showed that both bacteria and actinomycetes decreased by about 2 times in contrast to fungi, which increased by about 3 folds. Phosphorus bacteria, potassium bacteria, azotobacter, ammonia bacteria, and nitrifying bacteria were also reduced significantly by REC, suggesting the inhibition of nitrogen biofixation and supply, mobilization of phosphorus and potassium, ad plant growth promotion as REC added into soil. There were multiple influences of REC on soil enzyme activities. Invertase activity was stimulated, while urease was inhibited and dehydrogenase unchanged by REC, indicating the interference of biochemical reactions in soil. In addition, type and total content of phosphorus lipid fatty acids (PLFAs) , the signature of microbes, decreased while the ratio of bacterium to fungus PLFAs increased as REC increased in soil, which suggested that fungi increased relatively with bacteria decreased thereby leading to easy occurrence of crop fungus diseases following cultivation of C. chinensis. The decrease in diversity and evenness indexes of microbial community in soil by REC indicated soil ecosystem deterioration and reduction of microbial groups and densities in soil. Therefore, allelopathic chemicals released from the roots of C. chinensis could change microbial community structure and resulted in serious soil problems by continual cropping of this medicinal plant.

Dual-delivery of vancomycin and icariin from an injectable calcium phosphate cement-release system for controlling infection and improving bone healing.

Infectious bone diseases following severely contaminated open fractures are frequently encountered in clinical practice. It is difficult to successfully repair bone and control infection at the same time. To identify a better treatment method, we prepared a dual-drug release system that was comprised of icariin (IC, a natural osteoinductive molecule), vancomycin (VA) and injectable calcium phosphate cement (CPC). The ultrastructure of the dual-drug release system was evaluated by scanning electron microscopy and the biocompatibility was assessed by cell culture. In addition, the release kinetics of IC and VA were respectively investigated by using high­performance liquid chromatography. Finally, this system was used to repair Staphylococcus aureus-contaminated bone defects in a rabbit model. Twelve weeks after the implantation of IC-VA/CPC, the contaminated bone defects were completely repaired, with significantly improved formation of lamellar bone and recanalization of the marrow cavity compared with the controls (CPC without antibiotics or osteoinductive agent). These results demonstrate that this dual-drug release system, with its concomitant antibiotic and osteoinductive properties, has significant potential for the treatment of contaminated bone injury or infectious bone disease.

[Effect of fertilization on phenolic components and antioxidant activities of Artemisia annua].

OBJECTIVE: A pot experiment with variable fertilizer treatments was carried out to study the influence of fertilization on the concentration and accumulation of polyphenols, scopoletin, chrysosplenol-D and chrysosplenetin in roots, stems and leaves and their antioxidant activities. The main aims were to fertilize scientifically in cultivation of Artemisia annua and improve the quality of the harvest organs. METHOD: These active components in leaves, stems and roots in the squaring stage were analyzed by HPLC and antioxidant activities of the extracts were evaluated by ultraviolet visible light colorimetric method. RESULT: The result showed the highest concentration of polyphenols, scopoletin, chrysosplenol-D and chrysosplenetin was in leaves, followed by stems and the lowest in roots. The antioxidant activities of the leaf extracts correlated positively with the concentrations of polyphenols, scopoletin, chrysosplenol-D and chrysosplenetin. Furthermore, fertilization promoted significantly the growth of A. annua, the biomass was increased by 57.37% (chemical fertilizer), 91.63% (mixture of chemical fertilizer and manure) and 92.27% (manure), respectively, compared to the blank control (without fertilizer). Fertilization, particularly mixture fertilization of chemical fertilizer and manure, increased generally the concentration and accumulation of polyphenols, scopoletin, chrysosplenol-D and chrysosplenetin as well as DPPH x scavenging ratio. CONCLUSION: Scopoletin, chrysosplenol-D and chrysosplenetin could be synthesized and stored mainly in leaves. The leaves might thus be the chief organ of A. annua for medical treatment. Finally, the mixture fertilization of chemical fertilizer and manure should be used to increase the yield and quality of A. annua.

[Allelopathic effect of artemisinin on green algae].

To study the growth effects of differing concentrations of artemisinin on green algae and to evaluate the ecological risk. The effects of artemisinin on the growth and the content change of chlorophyll, protein, oxygen, conductivity, SOD, CAT, MDA in Chlorella pyrenoidosa and Scenedesmus oblique were studied through 96 h toxicity tests. Artemisinin accelerated the growth of algae at a lower concentration ( <40 microg . L-1) with content increase of chlorophyll or protein and so on, and it inhibited the growth of algae at higher concentration ( >80 microg . L-1). The content of chlorophyll or protein in algae cells reduced with the increasing concentration of artemisinin, exhibiting the good concentration-effect relationship. SOD and CAT activity was stimulated at low concentrations ( <40 microg . L-1 ) and inhibited at high concentrations ( >80 microg . L- 1). However, MDA content increased significantly with the increase of concentration. According to the seven kinds of indicators changes, the time-response and dose-response suggested that the surfactant first hurt in Ch. pyrenoidosa was damaging membrane by changing membrane lipid molecules soluble. And primary mechanism on Chlorophyta cells might be related to the oxidation damage of lipid and other biological large molecules caused by artemisinin. The large-scale intensive planting of Artemisia annua may reduce the surrounding water productivity.

[Allelopathic effects of extracts from fibrous roots of Coptis chinensis on two leguminous species].

An experiment was carried out to study the allelopathic effects of Coptis chinensis fibrous root extracts (CRE) on the germination and seedling growth of Vicia faba and Pisum sativum in order to alleviate the allelopathic effects and increase land productivity. The seeds of both garden pea (P. sativum) and broad been (V. faba) were germinated in CRE solution of various concentrations, the germination rate, seedling growth and related physiological indexes were measured. The result indicated that there were no significant effects of CRE in low concentrations on seed germination, including both the rate and index, and seed vitality and membrane permeability. With the increment of CRE concentrations, however, the high seed membrane permeability and germination inhibition were observed. For example, the germination rates were reduced by 23.4% (P. sativum) and 9.5% (V. faba), respectively, in CRE solution with 800 mg . L-1. Simultaneously, soluble sugars and the free amino acids in the seeds were lower than those in the control (without CRE) after soaking seeds in CRE solutions. In addition, the seedling growth and nitrate reductase activity were stimulated by CRE at low concentrations in contrast to high concentrations which behaved otherwise and inhibited the nutrient utilization in endosperm. Therefore, the large amount of allelochemicals released from the roots and remains of C. chinensis in soils could inhibit the seed germination and seedling growth of legumes, which may lead to decrease even fail crop yields after growing this medical plant.