Enhanced biomass burning as a source of aerosol ammonium over cities in central China in autumn.

Atmospheric ambient gaseous ammonia (NH3), the most abundant alkaline gas, affects public health and climate change through its key role in the formation of secondary aerosols via reactions with acidic gases. Estimation of the contributions of ammonia sources is very challenging in the urban atmosphere. Stable nitrogen isotope ratio (δ15N) measurements have shown that urban aerosol NH4+ and gaseous NH3 are derived from fossil fuel combustion-related (FF) sources, such as coal combustion, NH3 slip, and vehicle exhaust, and volatilization-related sources, such as agriculture and urban water volatilization. Biomass burning (BB) sources, especially residential biofuel, can produce vast quantities of NH3 and other pollutants and may greatly influence air quality and contribute to increased urban NH3 emissions. In the present study, we continually collected PM2.5 samples at three urban sites in Central China during autumn and analyzed the major water-soluble ions and δ15N values of aerosol NH4+. The concentrations of NH4+ increased as the temperature decreased close to winter, whereas the δ15N values did not show this pattern. According to the Bayesian model after isotope fractionation correction, FF sources contributed to 56.4 ± 17.1%, 46.4 ± 18.2%, and 51.8 ± 14.9% of aerosol NH4+ in Nanchang, Wuhan, and Changsha, respectively, throughout autumn. The contributions from BB sources were 34.5 ± 20.4%, 46.4 ± 21.4%, and 40.4 ± 17.4% for Nanchang, Wuhan, and Changsha, respectively. We also found the fraction of aerosol NH4+ from BB increased in all three cities from September to November 2017, which was likely caused by increased heating demands with the decrease in temperature during the season. Furthermore, BB was responsible for a severe haze event (maximum PM2.5 of 205.69 µg/m3) in Nanchang. These findings suggest government controls to improve air quality should include BB sources in addition to FF sources.

Gab1 mediates PDGF signaling and is essential to oligodendrocyte differentiation and CNS myelination.

Oligodendrocytes (OLs) myelinate axons and provide electrical insulation and trophic support for neurons in the central nervous system (CNS). Platelet-derived growth factor (PDGF) is critical for steady-state number and differentiation of oligodendrocyte precursor cells (OPCs), but its downstream targets are unclear. Here, we show for the first time that Gab1, an adaptor protein of receptor tyrosine kinase, is specifically expressed in OL lineage cells and is an essential effector of PDGF signaling in OPCs in mice. Gab1 is downregulated by PDGF stimulation and upregulated during OPC differentiation. Conditional deletions of Gab1 in OLs cause CNS hypomyelination by affecting OPC differentiation. Moreover, Gab1 binds to downstream GSK3ß and regulated its activity, and thereby affects the nuclear accumulation of ß-catenin and the expression of a number of transcription factors critical to myelination. Our work uncovers a novel downstream target of PDGF signaling, which is essential to OPC differentiation and CNS myelination.

Leucine-Rich Glioma Inactivated 1 Promotes Oligodendrocyte Differentiation and Myelination via TSC-mTOR Signaling.

Leucine-rich glioma inactivated 1 (Lgi1), a putative tumor suppressor, is tightly associated with autosomal dominant lateral temporal lobe epilepsy (ADLTE). It has been shown that Lgi1 regulates the myelination of Schwann cells in the peripheral nervous system (PNS). However, the function and underlying mechanisms for Lgi1 regulation of oligodendrocyte differentiation and myelination in the central nervous system (CNS) remain elusive. In addition, whether Lgi1 is required for myelin maintenance is unknown. Here, we show that Lgi1 is necessary and sufficient for the differentiation of oligodendrocyte precursor cells and is also required for the maintenance of myelinated fibers. The hypomyelination in Lgi1-/- mice attributes to the inhibition of the biosynthesis of lipids and proteins in oligodendrocytes (OLs). Moreover, we found that Lgi1 deficiency leads to a decrease in expression of tuberous sclerosis complex 1 (TSC1) and activates mammalian target of rapamycin signaling. Together, the present work establishes that Lgi1 is a regulator of oligodendrocyte development and myelination in CNS.

Celecoxib Ameliorates Seizure Susceptibility in Autosomal Dominant Lateral Temporal Epilepsy.

Autosomal dominant lateral temporal epilepsy (ADLTE) is an inherited syndrome caused by mutations in the leucine-rich glioma inactivated 1 (LGI1) gene. It is known that glutamatergic transmission is altered in LGI1 mutant mice, and seizures can be reduced by restoring LGI1 function. Yet, the mechanism underlying ADLTE is unclear. Here, we propose that seizures in male LGI1-/- mice are due to nonsynaptic epileptiform activity in cortical neurons. We examined the intrinsic excitability of pyramidal neurons in the temporal cortex of male LGI1-/- mice and found that the voltage-gated K+ channel Kv1.2 was significantly downregulated. We also found that cytosolic phospholipase A2 (cPLA2)-cyclooxygenase 2 (Cox2) signaling was enhanced in LGI1-/- mice. Interestingly, Cox2 inhibition effectively restored the dysregulated Kv1.2 and reduced the intrinsic excitability of pyramidal neurons. Moreover, in vivo injection of celecoxib, an FDA-approved nonsteroidal anti-inflammatory drug, rescued the defective Kv1.2 (an ∼1.9-fold increase), thereby alleviating the seizure susceptibility and extending the life of LGI1-/- mice by 5 d. In summary, we conclude that LGI1 deficiency dysregulates cPLA2-Cox2 signaling to cause hyperexcitability of cortical pyramidal neurons, and celecoxib is a potential agent to manage human ADLTE.SIGNIFICANCE STATEMENT Haploinsufficiency of the leucine-rich glioma inactivated 1 (LGI1) gene is the major pathogenic basis for ADLTE, an inherited syndrome with no cure to date. Existing studies suggest that altered glutamatergic transmission in the hippocampus causes this disease, but the data are paradoxical. We demonstrate that the loss of LGI1 decreases Kv1.2 expression, enhances intrinsic excitability, and thereby causes epilepsy. Interestingly, for the first time, we show that an FDA-approved drug, celecoxib, rescues the Kv1.2 defect and alleviates seizure susceptibility in LGI1-/- mice, as well as improving their survival. Thus, we suggest that celecoxib is a promising drug for the treatment of ADLTE patients.

Inhibition of litter decomposition of two emergent macrophytes by addition of aromatic plant powder.

Aromatic plants show antimicrobial activity due to their essential oils, but their effect on litter decomposition is unclear. In this study, we evaluated the biomass loss and nutrient dynamics in leaf litters of two macrophytes (Miscanthus sacchariflorus and Carex brevicuspis) with and without addition of powdered material of the aromatic plant Polygonum hydropiper or the non-aromatic plant C. brevicuspis. The two powders had similar basic chemical qualities but P. hydropiperi had a higher essential oils concentration. Leaf litters of M. sacchariflorus and C. brevicuspis were incubated with powdered P. hydropiper or C. brevicuspis (500 g m-3, 250 g m-3, and no addition) for 120 days in a mesocosm experiment. Compared with the control (no addition), P. hydropiperi addition decelerated nutrient release and litter decomposition, while C. brevicuspis addition accelerated those processes. The nitrogen concentrations in both leaf litters and the phosphorus concentration in C. brevicuspis leaf litter were increased by addition of both plant powders. The fungal biomass in both leaf litters decreased after P. hydropiperi addition, due to the antifungal activity of its essential oils. These data indicate that the aromatic plant P. hydropiperi inhibits litter decomposition via its essential oils and that such inhibition is not species-specific.

Downregulation of Glutamate Transporter EAAT4 by Conditional Knockout of Rheb1 in Cerebellar Purkinje Cells.

Excitatory amino acid transporter 4 (EAAT4) is believed to be critical to the synaptic activity of cerebellar Purkinje cells by limiting extracellular glutamate concentrations and facilitating the induction of long-term depression. However, the modulation of EAAT4 expression has not been elucidated. It has been shown that Ras homolog enriched in brain (Rheb)/mammalian target of rapamycin (mTOR) signaling plays essential roles in the regulation of protein translation, cell size, and cell growth. In addition, we previously found that a cascade including mTOR suppression and Akt activation induces increased expression of EAAT2 in astrocytes. In the present work, we explored whether Rheb/mTOR signaling is involved in the regulation of EAAT4 expression using conditional Rheb1 knockout mice. Our results demonstrated that Rheb1 deficiency resulted in the downregulation of EAAT4 expression, as well as decreased activity of mTOR and increased activity of Akt. The downregulation of EAAT4 was also confirmed by reduced EAAT4 currents and slowed kinetics of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor-mediated currents. On the other hand, conditional knockout of Rheb1 did not alter the morphology of Purkinje cell layer and the number of Purkinje cells. Overall, our findings suggest that small GTPase Rheb1 is a modulator in the expression of EAAT4 in Purkinje cells.

Numb deficiency in cerebellar Purkinje cells impairs synaptic expression of metabotropic glutamate receptor and motor coordination.

Protein Numb, first identified as a cell-fate determinant in Drosophila, has been shown to promote the development of neurites in mammals and to be cotransported with endocytic receptors in clathrin-coated vesicles in vitro. Nevertheless, its function in mature neurons has not yet been elucidated. Here we show that cerebellar Purkinje cells (PCs) express high levels of Numb during adulthood and that conditional deletion of Numb in PCs is sufficient to impair motor coordination despite maintenance of a normal cerebellar cyto-architecture. Numb proved to be critical for internalization and recycling of metabotropic glutamate 1 receptor (mGlu1) in PCs. A significant decrease of mGlu1 and an inhibition of long-term depression at the parallel fiber-PC synapse were observed in conditional Numb knockout mice. Indeed, the trafficking of mGlu1 induced by agonists was inhibited significantly in these mutants, but the expression of ionotropic glutamate receptor subunits and of mGlu1-associated proteins was not affected by the loss of Numb. Moreover, transient and persistent forms of mGlu1 plasticity were robustly induced in mutant PCs, suggesting that they do not require mGlu1 trafficking. Together, our data demonstrate that Numb is a regulator for constitutive expression and dynamic transport of mGlu1.

The role of seedling recruitment from juvenile populations of Carex brevicuspis (Cyperaceae) at the Dongting Lake wetlands, China.

Seedlings and vegetative ramets may contribute differentially to the recruitment of clonal populations in different growth phases, but this has rarely been investigated. In this study, we quantified the number and survivorship of seedlings and vegetative ramets monthly in juvenile and mature populations of Carex brevicuspis. During the first growing season after flooding (from October to January), 9 seedlings m(-2) (13% of all established shoots) were found in juvenile populations, while no seedlings were found in mature populations. During the second growing season before flooding (from February to May), no new seedling recruits were found either in juvenile or in mature populations. All shoots of seedlings were withered during the dormant season (January and February), but 62.5% seedlings could produce vegetative ramets in the following growing season. During the dormant season, all the early emerging ramets (sprouted in October) withered, but the later emerging ones (sprouted in November and December) survived in both mature and juvenile populations. These results indicated that seedling recruitment was only apparent in juvenile populations of C. brevicuspis. The genetic diversity in mature C. brevicuspis populations may be established in juvenile populations by seedling recruitment, and sustained in mature populations by vegetative reproduction.

Essential roles of leucine-rich glioma inactivated 1 in the development of embryonic and postnatal cerebellum.

Leucine-rich glioma inactivated 1 (LGI1) is a secreted protein that interacts with ADAM transmembrane proteins, and its mutations are linked to human epilepsy. The function of LGI1 in CNS development remains undefined. Here, we report novel functions of LGI1 in the generation of cerebellar granule precursors (CGPs) and differentiation of radial glial cells (RGCs) in the cerebellum. A reduction in external granule layer thickness and defects in foliation were seen in embryonic and new-born LGI1 knockout (KO) mice. BrdU staining showed an inhibited proliferation of CGPs in KO embryos, which might be explained by the reduced Sonic hedgehog in embryos. In addition, the differentiation of RGCs into Bergmann glias was suppressed in KO mice. Enhanced Jagged1-Notch1 signaling in KO mice via reduced ß-secretase proteolysis suggests that altered phenotype of RGCs is due to abnormal Notch1 signaling. Together, our results demonstrate that LGI1 is an essential player in the cerebellar development.

LGI1 is involved in the development of mouse brain.

Mutations in leucine-rich glioma inactivated 1 (LGI1) are linked to human autosomal dominant lateral temporal lobe epilepsy. It has been shown that LGI1 prevents the inactivation of voltage-gated potassium channels, mediates postnatal maturation of glutamatergic synapses, and regulates excitatory neurotransmission. However, other functions of LGI1 in the central nervous system have not been elucidated. We found that LGI1 is involved in the development of the cerebellum and cortex. The thickness of external granule layer was reduced, and foliation was affected in the cerebellum of LGI1 knockout mice. Double staining with Pax6 and BrdU showed a significant inhibition of proliferation of granule cell precursors of knockout embryos. The differentiation of radial glia cells was also suppressed in knockout mice, as shown by increased radial glial cells and decreased Bergmann glias in the areas of the cerebellum and cortex. Thus, our data demonstrate that LGI1 may be an essential player in the development of the brain.

GSK3ß promotes the differentiation of oligodendrocyte precursor cells via ß-catenin-mediated transcriptional regulation.

Oligodendrocytes are generated by the differentiation and maturation of oligodendrocyte precursor cells (OPCs). The failure of OPC differentiation is a major cause of demyelinating diseases; thus, identifying the molecular mechanisms that affect OPC differentiation is critical for understanding the myelination process and repairing after demyelination. Although prevailing evidence shows that OPC differentiation is a highly coordinated process controlled by multiple extrinsic and intrinsic factors, such as growth factors, axon signals, and transcription factors, the intracellular signaling in OPC differentiation is still unclear. Here, we showed that glycogen synthase kinase 3ß (GSK3ß) is an essential positive modulator of OPC differentiation. Both pharmacologic inhibition and knockdown of GSK3ß remarkably suppressed OPC differentiation. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assays and Ki67 staining showed that the effect of GSK3ß on OPC differentiation was not via cell death. Conversely, activated GSK3ß was sufficient to promote OPC differentiation. Our results also demonstrated that the transcription of myelin genes was regulated by GSK3ß inhibition, accompanying accumulated nuclear ß-catenin, and reduced the expression of transcriptional factors that are relevant to the expression of myelin genes. Taken together, our study identified GSK3ß as a profound positive regulator of OPC differentiation, suggesting that GSK3ß may contribute to the inefficient regeneration of oligodendrocytes and myelin repair after demyelination.

C-terminal domain of ICA69 interacts with PICK1 and acts on trafficking of PICK1-PKCα complex and cerebellar plasticity.

BACKGROUND: PICK1 (protein interacting with C-kinase 1) is a PKC (protein kinase C)-binding protein, which is essential for synaptic plasticity. The trafficking of PKCα-PICK1 complex to plasma membrane is critical for the internalization of GluR2 and induction of long-term depression. ICA69 (islet cell autoantigen 69 kDa) is identified as a major binding partner of PICK1. While heteromeric BAR domain complex is suggested to underlie the interaction between PICK1 and ICA69, the role of C-terminal domain of ICA69 (ICAC) in PICK1-ICA69 complex is unknown. METHODOLOGY/PRINCIPAL FINDINGS: We found that ICAC interacted with PICK1 and regulated the trafficking of PICK1-PKCα complex. ICAC and ΔICAC (containing BAR domain) might function distinctly in the association of ICA69 with PICK1. While ΔICAC domain inclined to form clusters, the distribution of ICAC was diffuse. The trafficking of PICK1 to plasma membrane mediated by activated PKCα was inhibited by ICA69. This action might ascribe to ICAC, because overexpression of ICAC, but not ΔICAC, interrupted PKCα-mediated PICK1 trafficking. Notably, infusion of maltose binding protein (MBP) fusion protein, MBP-ICA69 or MBP-ICAC, in cerebellar Purkinje cells significantly inhibited the induction of long-term depression at parallel fiber- and climbing fiber-Purkinje cell synapses. CONCLUSIONS: Our experiments showed that ICAC is an important domain for the ICA69-PICK1 interaction and plays essential roles in PICK1-mediated neuronal plasticity.

Upregulation of glutamate transporter GLT-1 by mTOR-Akt-NF-кB cascade in astrocytic oxygen-glucose deprivation.

Excessive extracellular glutamate leads to neuronal death in central nervous system. Excitatory glutamate transporter subtype 2 (GLT-1) carries bulk of glutamate reuptake in cerebral ischemia. Although GLT-1 expression fluctuates during the period of ischemia, little is known about its regulatory mechanism. Here we show an up-regulation of GLT-1 via mammalian target of rapamycin (mTOR)-Akt-nuclear factor-кB (NF-кB) signaling cascade in oxygen glucose deprivation (OGD). We found that brief rapamycin treatment significantly increased GLT-1 expression in cultured astrocytes. Rapamycin increased phosphorylation of raptor at Ser792 and decreased phosphorylation of rictor at Thr1135, suggesting that both mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) are involved in GLT-1 expression. This conclusion was further confirmed by raptor and rictor disruption experiments. Akt was activated by mTORC1 inhibition and required for GLT-1 expression because triciribine, a specific inhibitor of Akt, blocked the increase of GLT-1 expression. mTOR-Akt cascade then activated NF-кB and increased кB-motif-binding phosphoprotein (KBBP) expression and GLT-1 transcription. We next demonstrated that mTOR-Akt-NF-кB cascade was activated in OGD and subsequently caused the upregulation of GLT-1. Supporting evidence included: (1) inhibition of Akt or NF-кB occluded OGD-induced GLT-1 upregulation; (2) Raptor knock-down plus OGD did not add to the increase of GLT-1 expression; (3) Intact mTORC2 was required for GLT-1 enhancement. In summary, our data first showed that mTOR-Akt-NF-кB cascade played critical roles to up-regulate GLT-1 in OGD. This signaling cascade may work to promote glutamate uptake in brain ischemia and neurodegenerative diseases.

Distinct functions of nuclear distribution proteins LIS1, Ndel1 and NudCL in regulating axonal mitochondrial transport.

Neurons critically depend on the long-distance transport of mitochondria. Motor proteins kinesin and dynein control anterograde and retrograde mitochondrial transport, respectively in axons. The regulatory molecules that link them to mitochondria need to be better characterized. Nuclear distribution (Nud) family proteins LIS1, Ndel1 and NudCL are critical components of cytoplasmic dynein complex. Roles of these Nud proteins in neuronal mitochondrial transport are unknown. Here we report distinct functions of LIS1, Ndel1 and NudCL on axonal mitochondrial transport in cultured hippocampal neurons. We found that LIS1 interacted with kinsein family protein KIF5b. Depletion of LIS1 enormously suppressed mitochondrial motility in both anterograde and retrograde directions. Inhibition of either Ndel1 or NudCL only partially reduced retrograde mitochondrial motility. However, knocking down both Ndel1 and NudCL almost blocked retrograde mitochondrial transport, suggesting these proteins may work together to regulate retrograde mitochondrial transport through linking dynein-LIS1 complex. Taken together, our results uncover novel roles of LIS1, Ndel1 and NudCL in the transport of mitochondria in axons.

Cytosolic phospholipase A2 alpha/arachidonic acid signaling mediates depolarization-induced suppression of excitation in the cerebellum.

BACKGROUND: Depolarization-induced suppression of excitation (DSE) at parallel fiber-Purkinje cell synapse is an endocannabinoid-mediated short-term retrograde plasticity. Intracellular Ca(2+) elevation is critical for the endocannabinoid production and DSE. Nevertheless, how elevated Ca(2+) leads to DSE is unclear. METHODOLOGY/PRINCIPAL FINDINGS: We utilized cytosolic phospholipase A(2) alpha (cPLA(2)α) knock-out mice and whole-cell patch clamp in cerebellar slices to observed the action of cPLA(2)α/arachidonic acid signaling on DSE at parallel fiber-Purkinje cell synapse. Our data showed that DSE was significantly inhibited in cPLA(2)α knock-out mice, which was rescued by arachidonic acid. The degradation enzyme of 2-arachidonoylglycerol (2-AG), monoacylglycerol lipase (MAGL), blocked DSE, while another catabolism enzyme for N-arachidonoylethanolamine (AEA), fatty acid amide hydrolase (FAAH), did not affect DSE. These results suggested that 2-AG is responsible for DSE in Purkinje cells. Co-application of paxilline reversed the blockade of DSE by internal K(+), indicating that large conductance Ca(2+)-activated potassium channel (BK) is sufficient to inhibit cPLA(2)α/arachidonic acid-mediated DSE. In addition, we showed that the release of 2-AG was independent of soluble NSF attachment protein receptor (SNARE), protein kinase C and protein kinase A. CONCLUSIONS/SIGNIFICANCE: Our data first showed that cPLA(2)α/arachidonic acid/2-AG signaling pathway mediates DSE at parallel fiber-Purkinje cell synapse.

[Silkworm excrement organic fertilizer: its nutrient properties and application effect].

In this paper, silkworm excrement was harmless-treated via controlled fermentation to prepare silkworm excrement organic fertilizer (SEOF). The nutrient properties of the SEOF were determined, and a pot experiment was conducted to examine the application effect of the fertilizer. After fermentation, the total N, P, and K contents in the SEOF had a significant increase, being 58.0%, 84.4% , and 29.7% higher than those in the raw material, respectively. The addition of microbial inoculants shortened the fermentation period, and decreased the carbon and nitrogen losses during fermentation. With the application of SEOF, the seed germination index of cabbage and tomato was higher than 80% , suggesting that the fertilizer had no inhibitory effect on the seed germination. The application of SEOF not only increased the Chinese cabbage yield and its nutrients and Vc contents, decreased the plant nitrate content, but also improved the soil pH value, and increased the soil available nutrients and organic matter contents and soil enzyme activities, with better effect than applying composted goat feces.