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Plants respond to environmental stresses through controlled stem cell maintenance and meristem activity. One level of gene regulation is RNA alternative splicing. However, the mechanistic link between stress, meristem function and RNA splicing is poorly understood. The MERISTEM-DEFECTIVE (MDF) Arabidopsis gene encodes an SR-related family protein, required for meristem function and leaf vascularization, and is the likely orthologue of the human SART1 and yeast Snu66 splicing factors. MDF is required for the correct splicing and expression of key transcripts associated with root meristem function. We identified RSZ33 and ACC1, both known to regulate cell patterning, as splicing targets required for MDF function in the meristem. MDF expression is modulated by osmotic and cold stress, associated with differential splicing and specific isoform accumulation and shuttling between nucleus and cytosol, and acts in part via a splicing target SR34. We propose a model in which MDF controls splicing in the root meristem to promote stemness and to repress stress response, cell differentiation and cell death pathways.

Plants respond to environmental stresses through controlled stem cell maintenance and meristem activity. One level of transcriptional control is RNA alternative splicing. However the mechanistic link between stress, meristem function and RNA splicing is poorly understood. TheMERISTEM-DEFECTIVE(MDF)/DEFECTIVELY ORGANIZED TRIBUTARIES(DOT2) gene of Arabidopsis encodes a SR-related family protein, required for meristem function and leaf vascularization, and is the likely orthologue of the human SART1 and yeast snu66 splicing factors. MDF is required for the correct splicing and expression of key transcripts associated with root meristem function. We identifiedRSZ33andACC1, both known to regulate cell patterning, as splicing targets required for MDF function in the meristem.MDFexpression is modulated by osmotic and cold stress, associated with differential splicing and specific isoform accumulation and shuttling between nucleus and cytosol, and acts in part via a splicing targetSR34. We propose a model in which MDF controls splicing in the root meristem to promote stemness and repress stress response and cell differentiation pathways.Summary statementThe protein MERISTEM-DEFECTIVE regulates Arabidopsis meristem function through its role as a splicing factor, mediated through splicing targets RSZ33, ACC1 and SR34.

Artificial intelligence in the form of deep neural networks have taken off in the last few years and AI-based applications have become a part of our everyday life. However, the start of modern AI revolution can be traced back to a program that won a computer vision competition in 2012: AlexNet. Since then, the field has made dramatic progress, with many programs significantly beating the results from AlexNet. This report addresses the evolution of some of the representative models, and discusses the advances, the challenges, and major points of research in the field today.

Over the past decades, various theories and algorithms have been developed under the framework of Stackelberg games and part of these innovations have been fielded under the scenarios of national security defenses and wildlife protections. However, one of the remaining difficulties in the literature is that most of theoretical works assume full information of the payoff matrices, while in applications, the leader often has no prior knowledge about the follower’s payoff matrix, but may gain information about the follower’s utility function through repeated interactions. In this paper, we study the problem of learning the optimal leader strategy in Stackelberg (security) games and develop novel algorithms as well as new hardness results.

The genome of recombinant adeno-associated virus 2 (rAAV2) remains a promising candidate for gene therapy for cystic fibrosis (CF) lung disease, but due to limitations in the packaging capacity and the tropism of this virus with respect to the airways, strategies have evolved for packaging an rAAV2 genome (up to 5.8 kb) into the capsid of human bocavirus 1 (HBoV1) to produce a chimeric rAAV2/HBoV1 vector. Although a replication-incompetent HBoV1 genome has been established as a trans helper for capsid complementation, this system remains suboptimal with respect to virion yield. Here, a streamlined production system is described based on knowledge of the involvement of HBoV1 nonstructural (NS) proteins NS1, NS2, NS3, NS4, and NP1 in the process of virion production. The analyses reveal that NS1 and NS2 negatively impact virion production, NP1 is required to prevent premature termination of transcription of the cap mRNA from the native genome, and silent mutations within the polyadenylation sites of the cap coding sequence can eliminate this requirement for NP1. It is further shown that preventing the expression of all NS proteins significantly increases virion yield. Whereas the expression of capsid proteins VP1, VP2, and VP3 from a codon-optimized cap mRNA was highly efficient, optimal virion assembly, and thus potency, required enhanced VP1 expression, entailing a separate VP1 expression cassette. The final NS protein-free production system uses three-plasmid co-transfection of HEK293 cells, with one trans helper plasmid encoding VP1 and the AAV2 Rep proteins, and another encoding VP2-3 and components from adenovirus. This system yielded >16-fold more virions than the prototypic system, without reducing transduction potency. This increase in virion production is expected to facilitate greatly both research on the biology of rAAV2/HBoV1 and preclinical studies testing the effectiveness of this vector for gene therapy of CF lung disease in large animal models.

We study the use of deception in attack graph-based Stackelberg security games. In our setting, in addition to allocating defensive resources to protect important targets from attackers, the defender can strategically manipulate the attack graph through three main types of deceptive actions. We show that finding the optimal deception and defense strategy is at least NP-hard. We provide two techniques for efficiently solving this problem: a mixed-integer linear program for layered directed acyclic graphs (DAGs) and neural architecture search for general DAGs. We empirically demonstrate that using deception on attack graphs gives the defender a significant advantage, and the algorithms we develop scale gracefully to medium-sized problems.

Over the past few years, ride-sharing has emerged as an effective way to relieve traffic congestion. A key problem for the ride-sharing platforms is to come up with a revenue-optimal (or GMV-optimal) pricing scheme and a vehicle dispatching policy that incorporate geographic and temporal information. In this paper, we aim to tackle this problem via an economic approach. Modeled naively, the underlying optimization problem may be non-convex and thus hard to solve. To this end, we use a so-called ``ironing'' technique to convert the problem into an equivalent convex optimization one via a clean Markov decision process (MDP) formulation, where the states are the driver distributions and the decision variables are the prices for each pair of locations. Our main finding is an efficient algorithm that computes the exact revenue-optimal (or GMV-optimal) randomized pricing scheme, which naturally induces the accompany vehicle dispatching policy. We also conduct empirical evaluations of our solution through real data of a major ride-sharing platform and show its advantages over fixed pricing schemes as well as several prevalent surge-based pricing schemes.

Lytic infection of human parvovirus B19 (B19V) takes place exclusively in human erythroid progenitor cells of bone marrow and fetal liver, which disrupts erythropoiesis. During infection, B19V expresses three nonstructural proteins (NS1, 11-kDa, and 7.5-kDa) and two structural proteins (VP1 and VP2). While NS1 is essential for B19V DNA replication, 11-kDa enhances viral DNA replication significantly. In this study, we confirmed the enhancement role of 11-kDa in viral DNA replication and elucidated the underlying mechanism. We found that 11-kDa specially interacts with cellular growth factor receptor-bound protein 2 (Grb2) during virus infection and in vitro . We determined a high affinity interaction between 11-kDa and Grb2 that has an equilibrium dissociation constant ( K D ) value of 18.13 nM. In vitro , one proline-rich motif was sufficient for 11-kDa to sustain a strong interaction with Grb2. In consistence, in vivo during infection, one proline-rich motif was enough for 11-kDa to significantly reduce phosphorylation of extracellular signal-regulated kinase (ERK). Mutations of all three proline-rich motifs of 11-kDa abolished its capability to reduce ERK activity and, accordingly, decreased viral DNA replication. Transduction of a lentiviral vector encoding a short hairpin RNA (shRNA) targeting Grb2 decreased the expression of Grb2 as well as the level of ERK phosphorylation, which resulted in an increase of B19V replication. These results, in concert, indicate that the B19V 11-kDa protein interacts with cellular Grb2 to downregulate ERK activity, which upregulates viral DNA replication. IMPORTANCE Human parvovirus B19 (B19V) infection causes hematological disorders and is the leading cause of nonimmunological fetal hydrops during pregnancy. During infection, B19V expresses two structural proteins, VP1 and VP2, and three nonstructural proteins, NS1, 11-kDa, and 7.5-kDa. While NS1 is essential, 11-kDa plays an enhancing role in viral DNA replication. Here, we elucidated a mechanism underlying 11-kDa protein-regulated B19V DNA replication. 11-kDa is tightly associated with cellular growth factor receptor-bound protein 2 (Grb2) during infection. In vitro , 11-kDa interacts with Grb2 with high affinity through three proline-rich motifs, of which at least one is indispensable for the regulation of viral DNA replication. 11-kDa and Grb2 interaction disrupts extracellular signal-regulated kinase (ERK) signaling, which mediates upregulation of B19V replication. Thus, our study reveals a novel mechanism of how a parvoviral small nonstructural protein regulates viral DNA replication by interacting with a host protein that is predominately expressed in the cytoplasm.

Consider a repeated auction between one seller and many buyers, where each buyer only has an estimation of her value in each period until she actually receives the item in that period. The seller is allowed to conduct a dynamic auction to sell the items but must guarantee ex-post individual rationality. In other words, if the buyer realized that her value of the item she just received was zero, she did not need to pay anything. Unlike the clicks on the ads, these actions are private information only observable by the buyers (advertisers). Hence they may have incentives to misreport the user actions, because they can pay less under cost-per-action payment schemes with ex-post individual rationality guarantees. In this paper, we use a structure that we call credit accounts to enable a general reduction from any incentive compatible and ex-ante individual rational dynamic auction to an approximate incentive compatible and ex-post individually rational dynamic auction with credit accounts. Our reduction can obtain stronger individual rationality guarantees at of the cost of weaker incentive compatibility. Surprisingly, our reduction works without making any common knowledge assumptions. Finally, as a complement to our reduction, we prove that there is no non-trivial auction that is exactly incentive compatible and ex-post individually rational under this setting.

Human bocavirus 1 (HBoV1) is a single-stranded DNA parvovirus that causes lower respiratory tract infections in young children worldwide. In this study, we identified novel splice acceptor and donor sites, namely, A1′ and D1′, in the large nonstructural protein (NS1)-encoding region of the HBoV1 precursor mRNA. The novel small NS proteins (NS2, NS3, and NS4) were confirmed to be expressed following transfection of an HBoV1 infectious proviral plasmid and viral infection of polarized human airway epithelium cultured at an air-liquid interface (HAE-ALI). We constructed mutant pIHBoV1 infectious plasmids which harbor silent mutations (sm) smA1′ and smD1′ at the A1′ and D1′ splice sites, respectively. The mutant infectious plasmids maintained production of HBoV1 progeny virions at levels less than five times lower than that of the wild-type plasmid. Importantly, the smA1′ mutant virus that does not express NS3 and NS4 replicated in HAE-ALI as effectively as the wild-type virus; however, the smD1′ mutant virus that does not express NS2 and NS4 underwent an abortive infection in HAE-ALI. Thus, our study identified three novel NS proteins, NS2, NS3, and NS4, and suggests an important function of the NS2 protein in HBoV1 replication in HAE-ALI. IMPORTANCE Human bocavirus 1 infection causes respiratory diseases, including acute wheezing in infants, of which life-threatening cases have been reported. In vitro , human bocavirus 1 infects polarized human bronchial airway epithelium cultured at an air-liquid interface that mimics the environment of human lower respiratory airways. Viral nonstructural proteins are often important for virus replication and pathogenesis in infected tissues or cells. In this report, we identified three new nonstructural proteins of human bocavirus 1 that are expressed during infection of polarized human bronchial airway epithelium. Among them, we proved that one nonstructural protein is critical to the replication of the virus in polarized human bronchial airway epithelium. The creation of nonreplicating infectious HBoV1 mutants may have particular utility in vaccine development for this virus.

Over the past few years, ride-sharing has been proven to be an effective way to relieve urban traffic congestion, as evidenced by several emerging ride-sharing platforms such as Uber and Didi. A key economic problem for these platforms is to design a revenue-optimal (or welfare-optimal) pricing scheme and a corresponding vehicle dispatching policy that incorporates geographic information, and more importantly, dynamic supply and demand. In this paper, we aim to solve this problem by introducing a unified model that takes into account both travel time and driver redirection. We tackle the non-convexity problem using the "ironing" technique and formulate the optimization problem as a Markov decision process (MDP), where the states are the driver distributions and the decision variables are the prices. Our main finding is to give an efficient algorithm that computes the exact revenue (or welfare) optimal randomized pricing schemes. We characterize the optimal solutions of the MDP by primal-dual analysis of a convex program. We also conduct empirical analysis of our solution with real data of a major ride-sharing platform and show its significant advantages over fixed pricing schemes as well as those prevalent surge-based pricing schemes.

Human bocavirus 1 (HBoV1) belongs to the species Primate bocaparvovirus of the genus Bocaparvovirus of the Parvoviridae family. HBoV1 causes acute respiratory tract infections in young children and has a selective tropism for the apical surface of well-differentiated human airway epithelia (HAE). In this study, we identified an additional HBoV1 gene, bocavirus-transcribed small noncoding RNA (BocaSR), within the 3′ noncoding region (nucleotides [nt] 5199 to 5338) of the viral genome of positive sense. BocaSR is transcribed by RNA polymerase III (Pol III) from an intragenic promoter at levels similar to that of the capsid protein-coding mRNA and is essential for replication of the viral DNA in both transfected HEK293 and infected HAE cells. Mechanistically, we showed that BocaSR regulates the expression of HBoV1-encoded nonstructural proteins NS1, NS2, NS3, and NP1 but not NS4. BocaSR is similar to the adenovirus-associated type I (VAI) RNA in terms of both nucleotide sequence and secondary structure but differs from it in that its regulation of viral protein expression is independent of RNA-activated protein kinase (PKR) regulation. Notably, BocaSR accumulates in the viral DNA replication centers within the nucleus and likely plays a direct role in replication of the viral DNA. Our findings reveal BocaSR to be a novel viral noncoding RNA that coordinates the expression of viral proteins and regulates replication of viral DNA within the nucleus. Thus, BocaSR may be a target for antiviral therapies for HBoV and may also have utility in the production of recombinant HBoV vectors. IMPORTANCE Human bocavirus 1 (HBoV1) is pathogenic to humans, causing acute respiratory tract infections in young children. In this study, we identified a novel HBoV1 gene that lies in the 3′ noncoding region of the viral positive-sense genome and is transcribed by RNA polymerase III into a noncoding RNA of 140 nt. This bocavirus-transcribed small RNA (BocaSR) diverges from both adenovirus-associated (VA) RNAs and Epstein-Barr virus-encoded small RNAs (EBERs) with respect to RNA sequence, representing a third species of this kind of Pol III-dependent viral noncoding RNA and the first noncoding RNA identified in autonomous parvoviruses. Unlike the VA RNAs, BocaSR localizes to the viral DNA replication centers of the nucleus and is essential for expression of viral nonstructural proteins independent of RNA-activated protein kinase R and replication of HBoV1 genomes. The identification of BocaSR and its role in virus DNA replication reveals potential avenues for developing antiviral therapies.

Oligodendrocyte precursor cells (OPCs) originate from restricted regions of the brain and migrate into the developing white matter, where they differentiate into oligodendrocytes and myelinate axons in the central nervous system (CNS). The molecular mechanisms that orchestrate these long distance trips of OPCs to populate throughout the CNS are poorly understood. Emerging evidence has argued the expression of N-methyl-d-aspartic acid (NMDA) receptors (NMDARs) in oligodendrocyte lineage cells in vivo, but their physiological function remains elusive. We have previously demonstrated the expression and function of NMDARs in OPC differentiation and myelination/remyelination. Here, we show that NMDARs stimulation promotes OPC migration both by chemotaxis and chemokinesis as demonstrated by various cell migration systems including Boyden transwell, single cell, matrix-gel cell mass, and SVZ tissue explants assays. The pro-migration effect of NMDAR can be abolished by either pharmacological inhibition or shRNA knock down of the T lymphoma invasion and metastasis 1 (Tiam1), a Rac1 guanine nucleotide exchange factor (Rac1-GEF) which is coexpressed and interacts with NMDAR in OPCs. Moreover, NMDAR stimulation evokes cascade activation of the Tiam1/Rac1/ERK signaling pathway which mediates its effect on OPC migration. We also show that glutamate released from cultured cortical neuron promotes OPCs migration via NMDAR, and that antagonism of NMDAR or inhibition of Tiam1 blocks the endogenous glutamate-induced OPCs migration from SVZ to cortical plate in the embryonic brain slice culture. Thus, our result suggests a critical role of NMDAR in regulation of OPCs migration during CNS development by coupling to and activating the Tiam1/Rac1 pathway.

Differentiation of oligodendrocyte precursor cells (OPCs) is the most important event for the myelination of central nervous system (CNS) axons during development and remyelination in demyelinating diseases, while the underlying molecular mechanisms remain largely unknown. Here we show that NMDA receptor (NMDAR) is a functional regulator of OPCs differentiation and remyelination. First, GluN1, GluN2A, and GluN2B subunits are expressed in oligodendrocyte lineage cells (OLs) in vitro and in vivo by immunostaining and Western blot analysis. Second, in a purified rat OPC culture system, NMDARs specially mediate OPCs differentiation by enhancing myelin proteins expression and the processes branching at the immature to mature oligodendrocyte transition analyzed by a serial of developmental stage-specific antigens. Moreover, pharmacological NMDAR antagonists or specific knockdown of GluN1 by RNA interference in OPCs prevents the differentiation induced by NMDA. NMDA can activate the mammalian target of rapamycin (mTOR) signal in OPCs and the pro-differentiation effect of NMDA is obstructed by the mTOR inhibitor rapamycin, suggesting NMDAR exerts its effect through mTOR-dependent mechanism. Furthermore, NMDA increases numbers of myelin segments in DRG-OPC cocultures. Finally, NMDAR specific antagonist MK801 delays remyelination in the cuprizone model examined by LFB-PAS, immunofluorescence and electron microscopy. This effect appears to result from inhibiting OPCs differentiation as more NG2(+) OPCs but less GST-π(+) mature oligodendrocytes are observed. Together, these results indicate that NMDAR plays a critical role in the regulation of OPCs differentiation in vitro and remyelination in cuprizone model which may provide potential target for the treatment of demyelination disease.

In many social systems in which individuals and organizations interact with each other, there can be no easy laws to govern the rules of the environment, and agents' payoffs are often influenced by other agents' actions. We examine such a social system in the setting of sponsored search auctions and tackle the search engine's dynamic pricing problem by combining the tools from both mechanism design and the AI domain. In this setting, the environment not only changes over time, but also behaves strategically. Over repeated interactions with bidders, the search engine can dynamically change the reserve prices and determine the optimal strategy that maximizes the profit. We first train a buyer behavior model, with a real bidding data set from a major search engine, that predicts bids given information disclosed by the search engine and the bidders' performance data from previous rounds. We then formulate the dynamic pricing problem as an MDP and apply a reinforcement-based algorithm that optimizes reserve prices over time. Experiments demonstrate that our model outperforms static optimization strategies including the ones that are currently in use as well as several other dynamic ones.

Human bocavirus 1 (HBoV1), an emerging human-pathogenic respiratory virus, is a member of the genus Bocaparvovirus of the Parvoviridae family. In human airway epithelium air-liquid interface (HAE-ALI) cultures, HBoV1 infection initiates a DNA damage response (DDR), activating all three phosphatidylinositol 3-kinase-related kinases (PI3KKs): ATM, ATR, and DNA-PKcs. In this context, activation of PI3KKs is a requirement for amplification of the HBoV1 genome (X. Deng, Z. Yan, F. Cheng, J. F. Engelhardt, and J. Qiu, PLoS Pathog, 12:e1005399, 2016, https://doi.org/10.1371/journal.ppat.1005399 ), and HBoV1 replicates only in terminally differentiated, nondividing cells. This report builds on the previous discovery that the replication of HBoV1 DNA can also occur in dividing HEK293 cells, demonstrating that such replication is likewise dependent on a DDR. Transfection of HEK293 cells with the duplex DNA genome of HBoV1 induces hallmarks of DDR, including phosphorylation of H2AX and RPA32, as well as activation of all three PI3KKs. The large viral nonstructural protein NS1 is sufficient to induce the DDR and the activation of the three PI3KKs. Pharmacological inhibition or knockdown of any one of the PI3KKs significantly decreases both the replication of HBoV1 DNA and the downstream production of progeny virions. The DDR induced by the HBoV1 NS1 protein does not cause obvious damage to cellular DNA or arrest of the cell cycle. Notably, key DNA replication factors and major DNA repair DNA polymerases (polymerase η [Pol η] and polymerase κ [Pol κ]) are recruited to the viral DNA replication centers and facilitate HBoV1 DNA replication. Our study provides the first evidence of the DDR-dependent parvovirus DNA replication that occurs in dividing cells and is independent of cell cycle arrest. IMPORTANCE The parvovirus human bocavirus 1 (HBoV1) is an emerging respiratory virus that causes lower respiratory tract infections in young children worldwide. HEK293 cells are the only dividing cells tested that fully support the replication of the duplex genome of this virus and allow the production of progeny virions. In this study, we demonstrate that HBoV1 induces a DDR that plays significant roles in the replication of the viral DNA and the production of progeny virions in HEK293 cells. We also show that both cellular DNA replication factors and DNA repair DNA polymerases colocalize within centers of viral DNA replication and that Pol η and Pol κ play an important role in HBoV1 DNA replication. Whereas the DDR that leads to the replication of the DNA of other parvoviruses is facilitated by the cell cycle, the DDR triggered by HBoV1 DNA replication or NS1 is not. HBoV1 is the first parvovirus whose NS1 has been shown to be able to activate all three PI3KKs (ATM, ATR, and DNA-PKcs).

A novel chimeric parvoviral vector, rAAV2/HBoV1, in which the recombinant adeno-associated virus 2 (rAAV2) genome is pseudopackaged by the human bocavirus 1 (HBoV1) capsid, has been shown to be highly efficient in gene delivery to human airway epithelia (Z. Yan et al., Mol Ther 21:2181–2194, 2013, http://dx.doi.org/10.1038/mt.2013.92 ). In this vector production system, we used an HBoV1 packaging plasmid, pHBoV1NSCap, that harbors HBoV1 nonstructural protein ( NS ) and capsid protein ( Cap ) genes. In order to simplify this packaging plasmid, we investigated the involvement of the HBoV1 NS proteins in capsid protein expression. We found that NP1, a small NS protein encoded by the middle open reading frame, is required for the expression of the viral capsid proteins (VP1, VP2, and VP3). We also found that the other NS proteins (NS1, NS2, NS3, and NS4) are not required for the expression of VP proteins. We performed systematic analyses of the HBoV1 mRNAs transcribed from the pHBoV1NSCap packaging plasmid and its derivatives in HEK 293 cells. Mechanistically, we found that NP1 is required for both the splicing and the read-through of the proximal polyadenylation site of the HBoV1 precursor mRNA, essential functions for the maturation of capsid protein-encoding mRNA. Thus, our study provides a unique example of how a small viral nonstructural protein facilitates the multifaceted regulation of capsid gene expression. IMPORTANCE A novel chimeric parvoviral vector, rAAV2/HBoV1, expressing a full-length cystic fibrosis transmembrane conductance regulator (CFTR) gene, is capable of correcting CFTR-dependent chloride transport in cystic fibrosis human airway epithelium. Previously, an HBoV1 nonstructural and capsid protein-expressing plasmid, pHBoV1NSCap, was used to package the rAAV2/HBoV1 vector, but yields remained low. In this study, we demonstrated that the nonstructural protein NP1 is required for the expression of capsid proteins. However, we found that the other four nonstructural proteins (NS1 to -4) are not required for expression of capsid proteins. By mutating the cis elements that function as internal polyadenylation signals in the capsid protein-expressing mRNA, we constructed a simple HBoV1 capsid protein-expressing gene that expresses capsid proteins as efficiently as pHBoV1NSCap does, and at similar ratios, but independently of NP1. Our study provides a foundation to develop a better packaging system for rAAV2/HBoV1 vector production.

Human parvovirus B19 (B19V) infection is highly restricted to human erythroid progenitor cells, in which it induces a DNA damage response (DDR). The DDR signaling is mainly mediated by the ATR (ataxia telangiectasia-mutated and Rad3-related) pathway, which promotes replication of the viral genome; however, the exact mechanisms employed by B19V to take advantage of the DDR for virus replication remain unclear. In this study, we focused on the initiators of the DDR and the role of the DDR in cell cycle arrest during B19V infection. We examined the role of individual viral proteins, which were delivered by lentiviruses, in triggering a DDR in ex vivo -expanded primary human erythroid progenitor cells and the role of DNA replication of the B19V double-stranded DNA (dsDNA) genome in a human megakaryoblastoid cell line, UT7/Epo-S1 (S1). All the cells were cultured under hypoxic conditions. The results showed that none of the viral proteins induced phosphorylation of H2AX or replication protein A32 (RPA32), both hallmarks of a DDR. However, replication of the B19V dsDNA genome was capable of inducing the DDR. Moreover, the DDR per se did not arrest the cell cycle at the G 2 /M phase in cells with replicating B19V dsDNA genomes. Instead, the B19V nonstructural 1 (NS1) protein was the key factor in disrupting the cell cycle via a putative transactivation domain operating through a p53-independent pathway. Taken together, the results suggest that the replication of the B19V genome is largely responsible for triggering a DDR, which does not perturb cell cycle progression at G 2 /M significantly, during B19V infection.

Spatial structure analysis was conducted on a previously published dataset of DDT species concentrations in topsoil samples from Tianjin, China ( p , p ′-DDT, p , p ′-DDD, p , p ′-DDE and ∑ p , p ′-DDTs). Positive nuggets were observed for all three DDT species and ∑ p , p ′-DDTs in the four directions modeled. The Nugget–Sill-Ratio values, 0.62, 0.50, 0.63 and 0.58, for p , p ′-DDT, p , p ′-DDE, p , p ′-DDD and ∑ p , p ′-DDTs respectively, indicated that spatial distribution of DDTs residue in Tianjin topsoil could be characterized with high randomness, on average more than 50%, and less than 50% variance is explainable. Nevertheless, all DDT species have evident spatial structure. These spatial structures are anisotropic, showing more extended transportation along the E–W direction. Furthermore, the spatial structure of p , p '-DDE is more evident than the two other species, i.e. p , p ′-DDE showed higher continuity in space than p , p ′-DDT and p , p ′-DDD, which signs a better mobilization of this species in the soil. Two-dimensional ordinary block kriging was applied to DDT concentrations dataset for mapping purposes. The mean errors were close to zero and the mean squared errors varied from 0.23 to 0.46 log units. The accuracy of interpolation proved to be acceptable for p , p ′-DDE and ∑ p , p ′-DDTs. However, for p , p ′-DDT and p , p ′-DDD, the interpolation results were accompanied by relatively high kriging errors, due to their high randomness in spatial distribution.

In this paper, we consider permutation manipulations by any subset of women in the men-proposing version of the Gale-Shapley algorithm. This paper is motivated by the college admissions process in China. Our results also answer an open problem on what can be achieved by permutation manipulations. We present an efficient algorithm to find a strategy profile such that the induced matching is stable and Pareto-optimal (in the set of all achievable stable matchings) while the strategy profile itself is inconspicuous. Surprisingly, we show that such a strategy profile actually forms a Nash equilibrium of the manipulation game. In the end, we show that it is NP-complete to find a manipulation that is strictly better for all members of the coalition. This result demonstrates a sharp contrast between weakly better off outcomes and strictly better-off outcomes.

A multimedia fate model with spatially resolved air and soil phases was developed and evaluated. The model was used for calculation of phenanthrene concentrations in air, water, soil, and sediment in Tianjin area and transport fluxes between the adjacent bulk phases under steady-state assumption. Both air and soil phases were divided into 3113 individual compartments of 4 km2 each to assess the spatial variation of phenanthrene concentrations and fluxes. Independently measured phenanthrene concentrations in air, water, and soil were used for model validation. The spatial variation in soil was validated using a set of measured phenanthrene concentrations of 188 surface soil samples collected from the area. Most data used either for model calculation or for model validation were collected during the last 5 years. As the results of the model validation, the calculated mean values for phenanthrene concentrations in various bulk phases are in fair agreement with those independently observed and are very close to those calculated using the model without spatial variation. The absolute difference between the calculated and the measured mean concentrations are 0.14, 0.48, and 0.13 log-units (mol/m3) for air, water, and soil, respectively. The spatial distribution patterns of phenanthrene in both air and soil were well modeled. Spatially, however, the model overestimated the soil phenanthrene level at low concentration range and underestimated it at high concentration range. The calculated distribution of phenanthrene in the air matches well with the emission from fossil fuel combustion, while the calculated distribution pattern in the soil is similar to that observed.

In 1998, sludge samples were taken from the sewage dischargechannels of Tianjin, China, and concentrations of 50 elementsand total organic carbon (TOC) were detected by inductively coupled plasma-atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA), and otherconventional methods, and the results are reported in thisstudy. The sludge samples contain high concentrations oforganic matter, with the median value of TOC 15.5%. Comparedwith sediments from the intertidal flats of Bohai Bay, highconcentrations of Sn, Zn, Cu, Pb, Sb, Bi, Cr, Ni, P and Ba areobserved in the sludge. However, rare earth elements, alkalielements, Ti and Al do not show a correlation with pollution.From the urban side to the coastal side, the spatial variationof concentrations of the pollution-related elements is quiteirregular, indicating that the channels receive dischargesalong the course. No significant pollution in sediments at theoutlets of the sewage discharge channels was observed, whichmay be attributed to the dispersion of pollutants andpurification of the Bohai Bay. Factor analysis has revealed thetwo controlling factors of `pollution' and `background' on theelemental composition of the sludge.

Oligodendrocyte precursor cells (OPCs) originate from restricted regions of the brain and migrate into the developing white matter, where they differentiate into oligodendrocytes and myelinate axons in the central nervous system (CNS). The molecular mechanisms that orchestrate these long distance trips of OPCs to populate throughout the CNS are poorly understood. Emerging evidence has argued the expression of N-methyl-d-aspartic acid (NMDA) receptors (NMDARs) in oligodendrocyte lineage cells in vivo, but their physiological function remains elusive. We have previously demonstrated the expression and function of NMDARs in OPC differentiation and myelination/remyelination. Here, we show that NMDARs stimulation promotes OPC migration both by chemotaxis and chemokinesis as demonstrated by various cell migration systems including Boyden transwell, single cell, matrix-gel cell mass, and SVZ tissue explants assays. The pro-migration effect of NMDAR can be abolished by either pharmacological inhibition or shRNA knock down of the T lymphoma invasion and metastasis 1 (Tiam1), a Rac1 guanine nucleotide exchange factor (Rac1-GEF) which is coexpressed and interacts with NMDAR in OPCs. Moreover, NMDAR stimulation evokes cascade activation of the Tiam1/Rac1/ERK signaling pathway which mediates its effect on OPC migration. We also show that glutamate released from cultured cortical neuron promotes OPCs migration via NMDAR, and that antagonism of NMDAR or inhibition of Tiam1 blocks the endogenous glutamate-induced OPCs migration from SVZ to cortical plate in the embryonic brain slice culture. Thus, our result suggests a critical role of NMDAR in regulation of OPCs migration during CNS development by coupling to and activating the Tiam1/Rac1 pathway.

Differentiation of oligodendrocyte precursor cells (OPCs) is the most important event for the myelination of central nervous system (CNS) axons during development and remyelination in demyelinating diseases, while the underlying molecular mechanisms remain largely unknown. Here we show that NMDA receptor (NMDAR) is a functional regulator of OPCs differentiation and remyelination. First, GluN1, GluN2A, and GluN2B subunits are expressed in oligodendrocyte lineage cells (OLs) in vitro and in vivo by immunostaining and Western blot analysis. Second, in a purified rat OPC culture system, NMDARs specially mediate OPCs differentiation by enhancing myelin proteins expression and the processes branching at the immature to mature oligodendrocyte transition analyzed by a serial of developmental stage-specific antigens. Moreover, pharmacological NMDAR antagonists or specific knockdown of GluN1 by RNA interference in OPCs prevents the differentiation induced by NMDA. NMDA can activate the mammalian target of rapamycin (mTOR) signal in OPCs and the pro-differentiation effect of NMDA is obstructed by the mTOR inhibitor rapamycin, suggesting NMDAR exerts its effect through mTOR-dependent mechanism. Furthermore, NMDA increases numbers of myelin segments in DRG-OPC cocultures. Finally, NMDAR specific antagonist MK801 delays remyelination in the cuprizone model examined by LFB-PAS, immunofluorescence and electron microscopy. This effect appears to result from inhibiting OPCs differentiation as more NG2(+) OPCs but less GST-π(+) mature oligodendrocytes are observed. Together, these results indicate that NMDAR plays a critical role in the regulation of OPCs differentiation in vitro and remyelination in cuprizone model which may provide potential target for the treatment of demyelination disease.

Human bocavirus 1 (HBoV1) has been identified as one of the etiological agents of wheezing in young children with acute respiratory-tract infections. In this study, we have obtained the sequence of a full-length HBoV1 genome (including both termini) using viral DNA extracted from a nasopharyngeal aspirate of an infected patient, cloned the full-length HBoV1 genome, and demonstrated DNA replication, encapsidation of the ssDNA genome, and release of the HBoV1 virions from human embryonic kidney 293 cells. The HBoV1 virions generated from this cell line-based production system exhibits a typical icosahedral structure of approximately 26 nm in diameter, and is capable of productively infecting polarized primary human airway epithelia (HAE) from the apical surface. Infected HAE showed hallmarks of lung airway-tract injury, including disruption of the tight junction barrier, loss of cilia and epithelial cell hypertrophy. Notably, polarized HAE cultured from an immortalized airway epithelial cell line, CuFi-8 (originally derived from a cystic fibrosis patient), also supported productive infection of HBoV1. Thus, we have established a reverse genetics system and generated the first cell line-based culture system for the study of HBoV1 infection, which will significantly advance the study of HBoV1 replication and pathogenesis., Author Summary Human bocavirus 1 (HBoV1) has been identified as one of the etiological agents of wheezing in young children with acute respiratory-tract infections. HBoV1 productively infects polarized primary human airway epithelia. However, no cell lines permissive to HBoV1 infection have yet been established. More importantly, the sequences at both ends of the HBoV1 genome have remained unknown. We have resolved both of these issues in this study. We have sequenced a full-length HBoV1 genome and cloned it into a plasmid. We further demonstrated that this HBoV1 plasmid replicated and produced viruses in human embryonic kidney 293 cells. Infection of these HBoV1 progeny virions produced obvious cytopathogenic effects in polarized human airway epithelia, which were represented by disruption of the epithelial barrier. Moreover, we identified an airway epithelial cell line supporting HBoV1 infection, when it was polarized. This is the first study to obtain the full-length HBoV1 genome, to demonstrate pathogenesis of HBoV1 infection in human airway epithelia, and to identify the first cell line to support productive HBoV1 infection.

Differentiation of oligodendrocyte progenitor cells (OPCs) into mature oligodendrocytes is a prerequisite for remyelination after demyelination, and impairment of this process is suggested to be a major reason for remyelination failure. Diosgenin, a plant-derived steroid, has been implicated for therapeutic use in many diseases, but little is known about its effect on the central nervous system. In this study, using a purified rat OPC culture model, we show that diosgenin significantly and specifically promotes OPC differentiation without affecting the viability, proliferation, or migration of OPC. Interestingly, the effect of diosgenin can be blocked by estrogen receptor (ER) antagonist ICI 182780 but not by glucocorticoid and progesterone receptor antagonist RU38486, nor by mineralocorticoid receptor antagonist spirolactone. Moreover, it is revealed that both ER-alpha and ER-beta are expressed in OPC, and diosgenin can activate the extracellular signal-regulated kinase 1/2 (ERK1/2) in OPC via ER. The pro-differentiation effect of diosgenin can also be obstructed by the ERK inhibitor PD98059. Furthermore, in the cuprizone-induced demyelination model, it is demonstrated that diosgenin administration significantly accelerates/enhances remyelination as detected by Luxol fast blue stain, MBP immunohistochemistry and real time RT-PCR. Diosgenin also increases the number of mature oligodendrocytes in the corpus callosum while it does not affect the number of OPCs. Taking together, our results suggest that diosgenin promotes the differentiation of OPC into mature oligodendrocyte through an ER-mediated ERK1/2 activation pathway to accelerate remyelination, which implicates a novel therapeutic usage of this steroidal natural product in demyelinating diseases such as multiple sclerosis (MS).

A level III fugacity model was applied to characterize the fate of gamma-HCH in Tianjin, China, before the 1990s when the contamination reached its maximum at steady state. Geometric means were used as model inputs. The concentrations of gamma-HCH in air, surface water, soil, sediment, crops, and fish as well as transfer fluxes across the interface between the compartments were derived under the assumption of steady state. The calculated concentrations were validated by independent data collected from the literature. There was generally good agreement between the estimated and the observed concentrations, and the differences were all less than 0.6 log units for air, water, soil, sediment, and fish and approximately 1 order of magnitude for crops. Around 97% of gamma-HCH accumulated in soil and sediment. Wastewater irrigation was not an important pathway for delivering gamma-HCH to soil as compared to the dominant source of agricultural application. Degradation and advective airflow carried much gamma-HCH out of the system. Sensitivities of the model estimates to input parameters were tested, and a coefficient of variation normalized sensitivity coefficient was defined for the test. The most influential parameters were degradation rates in sediment and soil, application rates, concentrations in wastewater, and adsorption coefficients. Monte Carlo simulation was conducted for model uncertainty analysis. The model was run 20 000 times using randomly generated data from predefined log-normal distribution density functions. All calculated concentrations and fluxes were log-normally distributed. The dispersions of the calculated and observed concentrations were compared in terms of coefficients of variation to distinguish between true variability and model uncertainty.

Behavior and fate of phenanthrene in various phases in Tianjin were calculated using a multimedia model with spatial resolution under steady-state assumption. Spatial variation of two parameters, namely soil organic carbon content and emission from fossil fuel combustion, were taken into consideration. Both soil and air phases were further divided into 3113 sub-compartments and 6226 equations in total were solved simultaneously under mass-balance assumption. A number of output parameters, therefore, were generated and were used for mapping of phenanthrene concentrations in soil and air, as well as transfer fluxes between compartments. The model was evaluated in two ways. 1. Comparison between the calculated and the observed average concentrations in bulk compartments, and 2. Comparison of spatial distribution of the calculated and the observed phenanthrene concentrations in surface soil. In both cases, the predicted results are in fair agreement with the independently measured values. As the results of the modeling, it was demonstrated that soil and sediment, especially the later, is the primary sink of phenanthrene in the area over 70% of the chemical accumulated in sediment. The spatial distribution pattern of phenanthrene in surface soil depends on content of soil organic matter which prevent the degradation of the material by bacteria. For distribution in ambient air, the dominant controlling factor is the emission.

The extraction efficiency of accelerated solvent extraction (ASE) was studied for organochlorine pesticide residuals in soil and compared with that of Soxhlet. The results showed that the efficiency of ASE was generally better than Soxhlet when used for DDT measurement, and equivalent to Soxhlet for BHCs. With ASE, organochlorine pesticide residues were detected in wastewater irrigated and non-wastewater irrigated soils from Tianjin. alpha-BHC, beta-BHC, delta-BHC, gamma-BHC, p,p'-DDE, p,p'-DDD, p,p'-DDT, o,p'-DDT ranged from 7.5 to 71.1 ng/g in wastewater irrigated vegetable and maize field and from 3.0 to 16.5 ng/g in wastewater irrigated paddy field. The eight pesticide residues from non-wastewater irrigated vegetable and maize field was in a range of 3.1-17.6 ng/g.