Azo-Cyanamide Bridged Dinuclear Iron Complexes Exhibiting no Electronic Coupling but Moderate Magnetic Coupling between the two Iron Centers.

To investigate the effect of long-distance organic ligand on electronic coupling between metallic atoms, the mononuclear and dinuclear complexes [Cp(dppe)Fe(apc)] (1), [{Cp(dppe)Fe}2(µ-adpc)] (2), [{CpMe5(dppe)Fe}2(µ-adpc) (3) and their oxidized complexes [Cp(dppe)Fe(apc)][PF6] (1[PF6]), [{Cp(dppe)Fe}2(µ-adpc)][PF6] (2[PF6]2), [{CpMe5(dppe)Fe}2(µ-adpc)][PF6]2 (3[PF6]2) (Cp=1,3-cyclopentadiene, CpMe5=1,2,3,4,5-pentamethylcyclopentadiene, dppe=1,2-bis(diphenylphosphino)ethane), apc-=4-azo(phenylcyanamido)benzene and adpc2-=4,4'-azodi(phenylcyanamido)) were synthesized and characterized by cyclic voltammetry, UV-vis, single-crystal X-ray diffraction and Mössbauer spectra. Electrochemical measurements showed no electronic coupling between the two terminal Fe units, However, the investigation results of the magnetic properties of the two-electron oxidized complexes indicate the presence of moderate antiferromagnetic coupling across 18 Šdistance.

The coupling effects of carbon fractions, bacteria, and protists on carbon emissions among various ditch levels in the Lower Yellow River.

Inland waters are receiving increasing attention due to their importance in the global carbon cycle. However, the dynamics of CO2 emissions and the related mechanisms from ditches remain unclear. In this study, field sampling and an incubation experiment were conducted to explore the effects and mechanisms, especially the coupling effects between carbon fractions, bacteria, and protists on carbon dynamics of different ditch levels (sublateral ditch, farm ditch, and lateral ditch) and sediment depths (0-20cm, 20-40cm) in the Lower Yellow River. Results indicated that sublateral ditches nearest to farmland had the highest accumulative carbon mineralization (0-20 cm 1.38 g C kg-1; 20-40 cm 0.89 g C kg-1), equivalent to that of farmland, followed by the lateral ditch (0-20 cm 0.84 g C kg-1; 20-40 cm 0.50 g C kg-1) and the farm ditch (0-20 cm 0.67 g C kg-1; 20-40 cm 0.26 g C kg-1). Carbon emissions from ditches are mainly regulated by SOC (36.97 %), bacteria (29.2 %), and protists (18.95 %). Specifically, the mineralization of flooded lateral ditches is attributed to protist diversity. SOC, bacterial and protistan diversity in the farm ditch significantly impacted carbon emissions, with SOC as the dominant factor, while the bacterial composition and SOC contributed more to CO2 emissions in the sublateral ditch. Our results highlight the importance of carbon emissions from ditches, especially those closest to farmland. This study provides new insights into the construction and management of farmland irrigation and drainage in the aspects of carbon sequestration.

Differences, links, and roles of microbial and stoichiometric factors in microplastic distribution: A case study of five typical rice cropping regions in China.

Microplastics (MPs), as new pollutants in agroecosystems, have already attracted widespread attention from scientists. However, our understanding of MP geographic distribution and its influencing factors across spatial scales remains poor. Here, a regional-scale field investigation was conducted to assess the distribution characteristic of MPs in five major rice-growing regions of China, and we explored the roles of biological and abiotic factors, especially stoichiometry and microbial influences on MP distribution. MPs were observed in all sampling sites, averaging 6,390 ± 2,031 items⋅kg-1. Sizes less than 0.5 mm and black and transparent MPs dominated. Fiber, classified as one of the MP shapes, occurred most frequently. MP community analysis, firstly used in paddy soil, revealed more black MPs abundance in Henan (HE), more rayon, blue, and other colors MPs in Hunan (HN), more transparent MPs in Tianjing (TJ), and more PE MPs in Heilongjiang (DB). Higher MP community diversity was found in most south paddy soils of this study, due to a broader range of sources. C/N showed a positive relationship with pellet-shaped MP abundance and MPs of size between 2 and 5 mm (P < 0.05). Chao1 index of soil microbial communities was positively correlated with the MP abundance, MPs of size less than 0.5 mm, and fiber abundance. The minimum temperature was positively correlated with MP abundance (P < 0.05), implying the potential effects of the freeze-thaw process might exist. The regression analysis highlighted the important role of population quantity in determining MP abundance (R = 0.421, P = 0.02). This study confirmed the wide distribution of MPs in different soil depths of paddy lands in China and demonstrated that its distribution was influenced by population quantity and environmental variables, such as microbiology. These findings could provide a basis for the toxicological behavior of MPs and the potential risk to human health.

Responses of Soil Microbial and Nematode Communities to Various Cover Crop Patterns in a Tea Garden of China.

As one of the typical farmland ecosystems, tea gardens are of vital importance in China. The purpose of this study was to quantify the dynamic of soil properties, soil microbial diversity, and nematodes, as affected by various cover crop patterns in a Tanjiawan tea garden in Hubei Province, China. Four cover crop patterns were established as following: naturally covered of bare land and mixed planting with two species, four species, and eight species. The results revealed that soil organic matter, pH, and total phosphorous content were significantly related to cover crop patterns. The number of nematodes increased with cover crop diversity, and the percentage of plant parasitic nematodes in cover crop treatments was lower than in naturally covered bare land. A higher diversity of cover crops increased the number of bacterivores and fungivores, thereby enhancing the bacterial decomposition pathway of soil organic matter. Both soil nematodes and microbial communities showed significant seasonal changes under different cover crop patterns. The soil food webs were more stable and mature under cover crops with two species and four species. Combined with the results of a structural equation model, we found that soil properties, characterized by the total nitrogen, available phosphorus, NO3--N, and soil organic matter, were significantly correlated with soil nematodes and microbial communities. In addition, acterivores and plant parasites were significantly negatively correlated with omnivores/predators. Our results implied that soil properties and seasonal changes influence the relationships between cover crops, soil nematodes, and microbial communities. These findings provide a theoretical basis for future studies on interactions between soil properties, soil microorganisms, and nematodes in tea gardens.

Effects of Bacillus thuringiensis Genetic Engineering on Induced Volatile Organic Compounds Emission in Maize and the Attractiveness to a Parasitic Wasp.

In order to control lepidopteran and coleopteran insects, the genes expressing Bacillus thuringiensis (Bt) insecticidal proteins have been transferred into crops. Ecological risk assessments of the transgenic plants have included impacts on non-target entomophagous insects, such as parasitoid wasps. Herbivore-induced plant volatiles are considered to be important defensive traits of plants because these compounds play as an important role in recruitment of natural enemies. Here, we evaluated induced volatile emissions of maize seedlings of two Bt cultivars (5422Bt1, event Bt11 and 5422CBCL, event Mon810), and their nearly isogenic non-Bt line 5422. We damaged plants mechanically and then applied with the regurgitant of Spodoptera litura (F.) caterpillars (Lepidoptera: Noctuidae), or treated the plants with the plant hormone jasmonic acid (JA), to trigger similar defensive responses of plants. Compared to the non-Bt isoline 5422 and the Bt maize 5422CBCL, the other Bt maize 5422Bt1 released more (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) when they were all treated by artificial wounds and caterpillar regurgitant; and released more linalool, DMNT and (E)-ß-farnesene when applied with JA solution. As a result, the total volatile emission of the 5422Bt1 was highest. However, the difference in volatile emission did not affect the attractiveness of the Bt maize plants to the egg parasitoid Trichogramma ostriniae Pang et Chen (Hymenoptera: Trichogrammatidae) compared to the nearly isogenic non-Bt plants. The variability of induced volatiles of maize cultivars derived from conventional breeding programs and transgenic methods are discussed.

Resolvin D1, an endogenous lipid mediator for inactivation of inflammation-related signaling pathways in microglial cells, prevents lipopolysaccharide-induced inflammatory responses.

BACKGROUNDS AND AIM: Microglial cells as an important part of central nervous system (CNS) have generally believed to play significant role in the process leading to a number of neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, prion diseases, multiple sclerosis, HIV-dementia, and stroke. Although different diseases have quite different pathogenesis, the activation of microglia was shared with all of them. Recently, the resolvin D1 (RvD1) as an endogenous antiinflammatory lipid mediator has been confirmed to be involved in the treatment of inflammation-related neuronal injury in neurodegenerative diseases. Therefore, the inhibition of microglia-activated inflammation has been considered as a major treatment strategy in neurodegenerative disease therapy. However, the molecular mechanisms of RvD1 in microglial cells remain unknown and still do not be reported. METHODS: We taken murine microglia as the experimental sample, and Western blotting, ELISA, reverse-transcriptase PCR, real-time PCR, and electrophoretic mobility shift assay were used to study whether the RvD1 inhibit inflammation of microglial cells. The tumor necrosis factor α (TNF-α), IL-1ß, inducible nitric oxide synthase (iNOS) expression, nuclear factor-κB (NF-κB) activation, and mitogen-activated protein kinase (MAPK) pathways were investigated in lipopolysaccharide (LPS)-activated primary microglia. RESULTS: Our data suggested that RvD1 inhibited the production of LPS-induced microglia inflammatory mediators and TNF-α, IL-1ß, and iNOS expression. In addition, according to the study of related signaling pathways, RvD1 attenuated LPS-induced microglia NF-κB activation,MAPK phosphorylation, and activator protein-1 transcriptional activity. CONCLUSION: This is the first study to demonstrate that RvD1 effects on the reduction of pro-inflammatory responses in LPS-induced microglial cells. The mechanisms underlying these effects may include its potent intracellular NF-κB down-regulation and subsequent pro-inflammatory cytokines release in LPS-activated microglia.