A Plant Virus Ensures Viral Stability in the Hemolymph of Vector Insects through Suppressing Prophenoloxidase Activation

Large ratios of vector-borne plant viruses circulate in the hemolymph of their vector insects before entering the salivary glands to be transmitted to plants. The stability of virions in the hemolymph is vital in this process. Activation of the proteolytic prophenoloxidase (PPO) to produce active phenoloxidase (PO) is one of the major innate immune pathways in insect hemolymph. How a plant virus copes with the PPO immune reaction in its vector insect remains unclear. Here, we report that the PPO affects the stability of rice stripe virus (RSV), a notorious rice virus, in the hemolymph of a vector insect, the small brown planthopper. RSV suppresses PPO activation using viral nonstructural protein. Once the level of PO activity is elevated, RSV is melanized and eliminated from the hemolymph. Our work gives valuable clues for developing novel strategies for controlling the transmission of vector-borne plant viruses.Most plant viruses require vector insects for transmission. Viral stability in the hemolymph of vector insects is a prerequisite for successful transmission of persistent plant viruses. However, knowledge of whether the proteolytic activation of prophenoloxidase (PPO) affects the stability of persistent plant viruses remains elusive. Here, we explored the interplay between rice stripe virus (RSV) and the PPO cascade of the vector small brown planthopper. Phenoloxidase (PO) activity was suppressed by RSV by approximately 60%. When the PPO cascade was activated, we found distinct melanization around RSV particles and serious damage to viral stability in the hemolymph. Viral suppression of PO activity was derived from obstruction of proteolytic cleavage of PPOs by binding of the viral nonstructural protein NS3. These results indicate that RSV attenuates the PPO response to ensure viral stability in the hemolymph of vector insects. Our research provides enlightening cues for controlling the transmission of vector-borne viruses

Experimental investigation of damage formation and material removal in ultrasonic assisted grinding of RBSiC

Ultrasonic assisted grinding (UAG) has been considered as a prominent processing method of the reaction bonded silicon carbide (RBSiC). To improve the knowledge of UAG process, both conventional grinding (CG) and UAG were used to process the RBSiC for in-depth investigation. Grinding forces, surface topographies, and subsurface damages during CG and UAG were compared. Furtherly, the ground surface was analyzed on aspects of both topographical characteristics and material removal mechanism. The results indicated that the removal of material is mainly achieved by the intersections of cracks initiated from both big SiC particles and mixture area of silicon matrix and small SiC grains. The crack propagation during UAG was more intensified due to the ultrasonic impact, which results in higher efficiency of machining RBSiC

Decoupling feldspar dissolution and precipitation rates at near-equilibrium with Si isotope tracers: Implications for modeling silicate weathering

Here we show that the isotope tracer experimental method for kinetic studies, aided by the recent advance and accessibility of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analysis for non-traditional stable isotopes, can provide unidirectional dissolution rates at near-equilibrium conditions. For a long time, the only rates available at near-equilibrium were net reaction rates—dissolution rates minus precipitation rates. This is because the conventional experimental method of kinetic studies is based on element concentrations and can only provide net rates. The availability of unidirectional rates allows us to re-examine some fundamental concepts and practices of modeling weathering in geochemistry. In this study, we used the 29Si isotope tracer to conduct albite and K-feldspar dissolution experiments at near-equilibrium conditions in near-neutral pH solutions at 50 °C. Results show that the saturation indices (SI) of solutions approached zero with respect to albite and K-feldspar after ∼240–360 h (h), but 29Si/28Si ratios of the experimental solutions indicated continual dissolution for another 720–1440 h. The rates of total Si precipitation were much smaller than the rates of Si dissolution. The experimental solutions were supersaturated with respect to amorphous Al(OH)3, gibbsite, quartz, allophane, imogolite, and kaolinite. The SI of the solutions remained constant with respect to these phases while Al concentrations slightly decreased and Si concentrations slightly increased, indicating the coupled feldspar dissolution and precipitation of secondary phases, such as albite → amorphous Al(OH)3 + quartz or albite → solution + Al-Si phase(s), instead of significant albite and K-feldspar precipitation (the reverse reaction) at 50 °C. Reaction path modeling of the temporal evolution of Si, Al, Na, and pH revealed that albite dissolution (without significant backward reaction) coupled with the precipitation of a secondary phase with a Si:Al ratio of ∼2:1 can successfully match the experimental data. Given the negligible feldspar precipitation reactions in low-temperature systems (e.g., T < 100 °C), we recommend modeling feldspar weathering using unidirectional forward rates together with secondary phase precipitation rates in near-equilibrium, feldspar-undersaturated systems. This can be accomplished with minor modifications in geochemical modeling software or input files. The coupled feldspar dissolution with secondary phase precipitation arrests the system in a near-equilibrium steady state. Using affinity-based rate equations such the classical linear Transition State Theory rate law or the Burch empirical relation together with far-from-equilibrium rate data will predict significant feldspar precipitation in solutions undersaturated but close to equilibrium with respect to feldspars, which is unlikely at near ambient temperatures

A timeline of oligodendrocyte death and proliferation following experimental subarachnoid hemorrhage

AimsWhite matter (WM) injury is a critical factor associated with worse outcomes following subarachnoid hemorrhage (SAH). However, the detailed pathological changes are not completely understood. This study investigates temporal changes in the corpus callosum (CC), including WM edema and oligodendrocyte death after SAH, and the role of lipocalin-2 (LCN2) in those changes.MethodsSubarachnoid hemorrhage was induced in adult wild-type or LCN2 knockout mice via endovascular perforation. Magnetic resonance imaging was performed 4 hours, 1 day, and 8 days after SAH, and T2 hyperintensity changes within the CC were quantified to represent WM edema. Immunofluorescence staining was performed to evaluate oligodendrocyte death and proliferation.ResultsSubarachnoid hemorrhage induced significant CC T2 hyperintensity at 4 hours and 1 day that diminished significantly by 8 days post-procedure. Comparing changes between the 4 hours and 1 day, each individual mouse had an increase in CC T2 hyperintensity volume. Oligodendrocyte death was observed at 4 hours, 1 day, and 8 days after SAH induction, and there was progressive loss of mature oligodendrocytes, while immature oligodendrocytes/oligodendrocyte precursor cells (OPCs) proliferated back to baseline by Day 8 after SAH. Moreover, LCN2 knockout attenuated WM edema and oligodendrocyte death at 24 hours after SAH.ConclusionsSubarachnoid hemorrhage leads to T2 hyperintensity change within the CC, which indicates WM edema. Oligodendrocyte death was observed in the CC within 1 day of SAH, with a partial recovery by Day 8. SAH-induced WM injury was alleviated in an LCN2 knockout mouse model.Lipocalin-2 deficiency attenuates corpus callosum T2 hyperintensity and oligodendrocyte death after SAH induction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/172271/1/cns13812.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/172271/2/cns13812_am.pd

Marine Carbonate Component in the Mantle Beneath the Southeastern Tibetan Plateau: Evidence From Magnesium and Calcium Isotopes

Tracing and identifying recycled carbonates is a key issue to reconstruct the deep carbon cycle. To better understand carbonate subduction and recycling beneath the southeastern Tibetan Plateau, high-K cal-alkaline volcanic rocks including trachy-basalts and trachy-andesites from Tengchong were studied using Mg and Ca isotopes. The low Mg-26 (-0.310.03 to -0.380.03) and Ca-44/40 (0.67 +/- 0.07 parts per thousand to 0.80 +/- 0.04 parts per thousand) values of these volcanic rocks compared to those of the mantle (-0.25 +/- 0.07 parts per thousand and 0.94 +/- 0.05 parts per thousand, respectively) indicate the incorporation of isotopically light materials into the mantle source, which may be carbonate-bearing sediments with low Mg-26 and Ca-44/40 values. In addition, no correlations of Mg-26 and Ca-44/40 with either SiO2 contents or trace element abundance ratios (e.g., Sm/Yb and Ba/Y) were observed, suggesting that limited Mg and Ca isotopic fractionation occurred during cal-alkaline magmatic differentiation. A binary mixing model using Mg-Ca isotopes shows that 5-8% carbonates dominated primarily by dolostone were recycled back into the mantle. Since Tengchong volcanism is still active and probably related to ongoing plate tectonic movement, we propose that the recycled carbonates are derived from oceanic crust related to the ongoing subduction of the Indian plate

Fe and Mg Isotope Compositions Indicate a Hybrid Mantle Source for Young Chang’E 5 Mare Basalts

The Chang’E 5 (CE-5) samples represent the youngest mare basalt ever known and provide an access into the late lunar evolution. Recent studies have revealed that CE-5 basalts are the most evolved lunar basalts, yet controversy remains over the nature of their mantle sources. Here we combine Fe and Mg isotope analyses with a comprehensive study of petrology and mineralogy on two CE-5 basalt clasts. These two clasts have a very low Mg# (∼29) and show similar Mg isotope compositions to Apollo low-Ti mare basalts as well as intermediate TiO _2 and Fe isotope compositions between low-Ti and high-Ti mare basalts. Fractional crystallization or evaporation during impact cannot produce such geochemical signatures that otherwise indicate a hybrid mantle source that incorporates both early- and late-stage lunar magma ocean (LMO) cumulates. Such a hybrid mantle source would be also compatible with the KREEP-like Rare Earth Elements pattern of CE-5 basalts. Overall, our new Fe–Mg isotope data highlight the role of late LMO cumulate for the generation of young lunar volcanism

SAIF plays anti-angiogenesis via blocking VEGF-VEGFR2-ERK signal in tumor treatment

Shark cartilage was created as a cancer-fighting diet because it was believed to have an element that may suppress tumor growth. Due to overfishing, sharks have become endangered recently, making it impossible to harvest natural components from shark cartilage for therapeutic development research. Previously, we identified a peptide SAIF from shark cartilage with an-tiangiogenic and anti-tumor effects, successfully expressed it in Escherichia coli by using genetic engineering techniques. However, we did not elucidate the specific target of SAIF and its antiangiogenic molecular mechanism, which hindered its further drug development. Therefore, in this work, the exact mechanism of action was studied using various techniques, including cellular and in vivo animal models, computer-aided simulation, molecular target capture, and transcriptome sequencing analysis. With VEGF-VEGFR2 interaction and preventing the activation of VEGFR2/ERK signaling pathways, SAIF was discovered to decrease angiogenesis and hence significantly limit tumor development. The findings further demonstrated SAIF's strong safety and pharmaceutically potential. The evidence showed that SAIF, which is expressed by, is a potent and safe angiogenesis inhibitor and might be developed as a candidate peptide drug for the treatment of solid tumors such as hepatocellular carcinoma and other conditions linked with angiogenic overgrowth

Photodriven Nanopump with Self-Augmented ROS Generation and Controllable Drug Release for Precisely Tuning Tumor Photodynamic-Chemotherapy

Although the stimulus-responsive nanoplatform shows excellent drug delivery preponderance in controlling drug release, its application is still inevitably restricted by exogenous uncontrollability, scarce biocompatibility, and a complex tumor microenvironment. Here, a photodriven self-augmented precision controllable nanoplatform was constructed by designing a novel pump-type switch cross-linker with 1O2-activation to covalently cross-link the topoisomerase I of 7-ethyl-10-hydroxycamptothecin (SN38) concurrently loading chlorin e6 (Ce6) to obtain the anticipative nanopump-CNs. After laser irradiation, the nanopump can be controllably unlocked, realizing the self-enhanced cascade amplification process of producing reactive oxygen species (ROS) while releasing the chemotherapy drug. Significantly, SN38 can effectively increase the sensitivity of tumor-related organelles to ROS while inducing DNA damage in tumor cells, thus, amplifying the efficacy of photodynamics caused by Ce6. This cascade self-enhanced drug nanosystem based on exogenous controlled chemotherapy and photodynamic therapy is expected to provide a new perspective for designing nanomedicine with a precise regulation model for malignant tumor therapy