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In this paper, a reaction-diffusion \begin{document}$ ISCT $\end{document} rumor propagation model with general incidence rate is proposed in a spatially heterogeneous environment. We first summarize the well-posedness of global solutions. Then the basic reproduction number \begin{document}$ \mathcal{R}_0 $\end{document} is introduced for the model which contains the spatial homogeneity as a special case. The threshold-type dynamics are also established in terms of \begin{document}$ \mathcal{R}_0 $\end{document} , including the global asymptotic stability of the rumor-free steady state and the uniform persistence of all positive solutions. Furthermore, by applying a controller to this model, we investigate the optimal control problem. Employing the operator semigroup theory, we prove the existence, uniqueness and some estimates of the positive strong solution to the controlled system. Subsequently, the existence of the optimal control strategy is established with the aid of minimal sequence techniques and the first order necessary optimality conditions for the optimal control is deduced. Finally, some numerical simulations are performed to validate the main analysis. The results of our study can theoretically promote the regulation of rumor propagation on the Internet.

Interactomes are powerful tools for encoding and decoding complex life systems. Here, we generated a maize interactome map that integrates genomic interactions, transcriptomic co-expression networks, translatomic co-expression networks, and protein–protein interactions throughout the maize lifecycle. This map, containing over 9 million interactions in more than 5,000 functional modules, reveals extensive functional divergence for duplicate genes and a progressive increase in regulatory divergence between the two maize subgenomes during the flow of genetic information. This network enables dissecting and validating gene functions, re-constructing regulatory pathways, and deciphering molecular mechanisms underlying complex traits combining big data mining technique-machine learning. By applying this map to flowering-time, we identified 1,843 high-confidence genes enriched in eight molecular pathways that are related to flowering time. The function of 30 (out of 58 tested) genes, including 27 novel genes, was verified by loss-of-function mutagenesis. Furthermore, a new pathway involving histone modification was identified and confirmed to regulate flowering time. The interactome map illustrates how coherent sets of molecular interactions connect different types of functional elements and pathway modules to map a genome-wide functional wiring landscape, which will be applicable in a wide range of species.

Plant-parasitic nematodes (PPN) are among the most economically and ecologically damaging pests, causing severe losses of crop production worldwide. Chemical-based nematicides have been widely used, but these may have adverse effects on human health and the environment. Hence, biological control agents (BCAs) have become an alternative option for controlling PPN, since they are environmentally friendly and cost effective. Lately, a major effort has been made to evaluate the potential of a commercial grade strain of plant growth-promoting rhizobacteria (PGPR) as BCAs, because emerging evidence has shown that PGPR can reduce PPN in infested plants through direct and/or indirect antagonistic mechanisms. Direct antagonism occurs by predation, release of antinematicidal metabolites and semiochemicals, competition for nutrients, and niche exclusion. However, the results of direct antagonism may be inconsistent due to unknown endogenous and exogenous factors that may prevent PGPR from colonizing plant’s roots. On the other hand, indirect antagonism may occur from the induced systemic resistance (ISR) that primes whole plants to better fight against various biotic and abiotic constraints, actuating faster and/or stronger defense responses (adaption), enhancing their promise as BCAs. Hence, this review will briefly revisit (i) two modes of PGPR in managing PPN, and (ii) the current working models and many benefits of ISR, in the aim of reassessing current progresses and future directions for isolating more effective BCAs and/or developing better PPN management strategy.

In recent decades, drought has become a global problem for food security and agricultural production. A variety of strategies have been developed to enhance drought tolerance, but largely unsuccessful since most drought-responsive genes (DRGs) stimulate a stomata closure and in turn suppress plant growth and yield. To access if and/or how plants could enhance drought tolerance without trading off growth and development, we screened and isolated a plant growth-promoting rhizobacterium, Paenibacillus polymyxa CR1, capable of 1) priming drought tolerance and concurrently 2) increasing root growth in plants, e.g., Arabidopsis and soybean. In parallel, we uncovered that P. polymyxa CR1 3) induces the expression of two DRGs, Response to Desiccation (RD)29A and RD29B, 4) of which pattern upregulations are controlled by a diurnal rhythm. Besides, RD29A and RD29B act as 5) 'memory' genes; their transcript levels are increased to a greater extent when plants encountered P. polymyxa CR1 for the second time compared to an initial exposure. In line with these findings, T-DNA insertion mutant Arabidopsis of RD29A or RD29B displayed enhanced susceptibility to drought, without any change in stomata behaviors or growth rates, than wild-type plants. Hence, we conclude that RD29A or RD29B are unique, efficacious generic materials that can potentially aid in upgrading the plants own survival capacity against drought without reducing yield potential.

Plant parasitic nematodes (PPN) are microscopic roundworms that mostly develop an obligate parasitic relationship with hosts. Once PPN reach root surfaces, they slowly insert a stylet, needle-like structure, into and feed cytosolic nutrients from roots, which cause cell and tissue mortality (Fosu-Nyarko and Jones, 2016; Mitchum et al., 2013). Recently, these PPN-associated damages have become of great agricultural and economic importance resulting in an estimated annual loss of ∼14 percent of world crop production (Nicol et al., 2011). Thus, an urgent breakthrough is needed in developing effective and sustainable pest management programs such as new resistance cultivars. It is however not necessarily forthcoming, largely due to our little knowledge of the defense physiology of plants against PPN. Hence, this review will briefly revisit current working models of plant and PPN interactions with a focus of plant defense responses, and pinpoint information gaps within, which help revamp unique and alternative prospective for the future studies. Keywords: Plant parasitic nematodes (PPN), Hypersensitive response, Host specificity of PPN, Chemotaxis, Root exudates

SUMMARY Abscisic acid (ABA) is an important phytohormone controlling responses to abiotic stresses and is sensed by proteins from the PYR/PYL/RCAR family. To explore the genetic contribution of PYLs toward ABA-dependent and ABA-independent processes, we generated and characterized high-order Arabidopsis mutants with mutations in the PYL family. We obtained a pyl quattuordecuple mutant and found that it was severely impaired in growth and failed to produce seeds. Thus, we carried out a detailed characterization of a pyl duodecuple mutant, pyr1pyl1/2/3/4/5/7/8/9/10/11/12. The duo-decuple mutant was extremely insensitive to ABA effects on seed germination, seedling growth, stomatal closure, leaf senescence, and gene expression. The activation of SnRK2 protein kinases by ABA was blocked in the duodecuple mutant, but, unexpectedly, osmotic stress activation of SnRK2s was enhanced. Our results demonstrate an important role of basal ABA signaling in growth, senescence, and abscission and reveal that PYLs antagonize ABA-independent activation of SnRK2s by osmotic stress., In Brief Zhao et al. generated duodecuple and quattuordecuple Arabidopsis PYL ABA receptor mutants. Characterization of the mutants revealed that the ABA receptors are critical for plant growth and development and negatively regulate ABA-independent SnRK2 activity by interacting with and inhibiting osmotic stress-activated SnRK2 protein kinases.

Plant parasitic nematodes (PPN) are microscopic soil herbivores that cause damage to many economic crops. For the last century, it has been proposed that chemotaxis is the primary means by which PPN locate host plant roots. The identities and modes of action of chemoattractants that deliver host-specific messages to PPN, however, are still elusive. In this study, a unique multidimensional agar-based motility assay was developed to assess the impacts of root exudates on the short-range motility and orientation of PPN. Three PPN (Rotylenchulus reniformis, Meloidogyne incognita and Heterodera glycines) and root exudates from their respective host and non-host plants (cotton, soybean, and peanut) were used to validate the assay. As predicted, R. reniformis and M. incognita were attracted to root exudates of cotton and soybean (hosts), but not to the exudates of peanut (non-host). Likewise, H. glycines was attracted to soybean (host) root exudates. These results underpinned the intrinsic roles of root exudates in conveying the host specificity of PPN. In particular, PPN selectively identified and targeted to hydrophilic, but not hydrophobic, fractions of root exudates, indicating that groundwater should be an effective matrix for chemotaxis associated with PPN and their host plant interactions.

Most of the previous work on rumor propagation either focus on ordinary differential equations with temporal dimension or partial differential equations (PDE) with only consideration of spatially independent parameters. Little attention has been given to rumor propagation models in a spatiotemporally heterogeneous environment. This paper is dedicated to investigating a SCIR reaction-diffusion rumor propagation model with a general nonlinear incidence rate in both heterogeneous and homogeneous environments. In spatially heterogeneous case, the well-posedness of global solutions is established first. The basic reproduction number \begin{document}$ R_0 $\end{document} is introduced, which can be used to reveal the threshold-type dynamics of rumor propagation: if \begin{document}$ R_0 , the rumor-free steady state is globally asymptotically stable, while \begin{document}$ R_0 > 1 $\end{document} , the rumor is uniformly persistent. In spatially homogeneous case, after introducing the time delay, the stability properties have been extensively studied. Finally, numerical simulations are presented to illustrate the validity of the theoretical analysis and the influence of spatial heterogeneity on rumor propagation is further demonstrated.

Posttranslational modification by a reduced glutathione determines distinctive quaternary structures and functions between two 2-cysteine peroxiredoxin A and B in the chloroplasts., In plants, growth-defense trade-offs occur because of limited resources, which demand prioritization towards either of them depending on various external and internal factors. However, very little is known about molecular mechanisms underlying their occurrence. Here, we describe that cyclophilin 20-3 (CYP20-3), a 12-oxo-phytodienoic acid (OPDA)–binding protein, crisscrosses stress responses with light-dependent electron reactions, which fine-tunes activities of key enzymes in plastid sulfur assimilations and photosynthesis. Under stressed states, OPDA, accumulates in the chloroplasts, binds and stimulates CYP20-3 to convey electrons towards serine acetyltransferase 1 (SAT1) and 2-Cys peroxiredoxin A (2CPA). The latter is a thiol-based peroxidase, protecting and optimizing photosynthesis by reducing its toxic byproducts (e.g., H2O2). Reduction of 2CPA then inactivates its peroxidase activity, suppressing the peroxide detoxification machinery, whereas the activation of SAT1 promotes thiol synthesis and builds up reduction capacity, which in turn triggers the retrograde regulation of defense gene expressions against abiotic stress. Thus, we conclude that CYP20-3 is a unique metabolic hub conveying resource allocations between plant growth and defense responses (trade-offs), ultimately balancing optimal growth phonotype.

DNA methylation confers epigenetic regulation on gene expression and thereby on various biological processes. Tomato has emerged as an excellent system to study the function of DNA methylation in plant development. To date, regulation and function of DNA methylation maintenance remains unclear in tomato plants. Here, we report the critical function of tomato (Solanum lycopersicum) Methyltransferase 1 (SlMET1) in plant development and DNA methylome and transcriptome regulation. Using CRISPR-Cas9 gene editing, we generated slmet1 mutants and observed severe developmental defects with a frame-shift mutation, including small and curly leaves, defective inflorescence, and parthenocarpy. In leaf tissues, mutations in SlMET1 caused CG hypomethylation and CHH hypermethylation on a whole-genome scale, leading to a disturbed transcriptome including ectopic expression of many RIN target genes such as ACC2 in leaf tissues, which are normally expressed in fruits. Neither the CG hypomethylation nor CHH hypermethylation in the slmet1 mutants is related to tissue culture. Meanwhile, tissue culture induces non-CG hypomethylation, which occurs more frequently at gene regions than at TE regions. Our results depict SlMET1- and tissue culture-dependent tomato DNA methylomes, and that SlMET1 is required for maintaining a normal transcriptome and normal development of tomato.

CRISPR/Cas9 and TALEN are currently the two systems of choice for genome editing. We have studied the efficiency of the TALEN system in rice as well as the nature and inheritability of TALEN-induced mutations and found important features of this technology. The N287C230 TALEN backbone resulted in low mutation rates (0-6.6%), but truncations in its C-terminal domain dramatically increased efficiency to 25%. In most transgenic T0 plants, TALEN produced a single prevalent mutation accompanied by a variety of low-frequency mutations. For each independent T0 plant, the prevalent mutation was present in most tissues within a single tiller as well as in all tillers examined, suggesting that TALEN-induced mutations occurred very early in the development of the shoot apical meristem. Multigenerational analysis showed that TALEN-induced mutations were stably transmitted to the T1 and T2 populations in a normal Mendelian fashion. In our study, the vast majority of TALEN-induced mutations (~81%) affected multiple bases and ~70% of them were deletions. Our results contrast with published reports for the CRISPR/Cas9 system in rice, in which the predominant mutations affected single bases and deletions accounted for only 3.3% of the overall mutations.

Microbes have long been used in the industry to produce valuable biochemicals. Combinatorial engineering approaches, new strain engineering tools derived from inverse metabolic engineering, have started to attract attention in recent years, including genome shuffling, error-prone DNA polymerase, global transcription machinery engineering (gTME), random knockout/overexpression libraries, ribosome engineering, multiplex automated genome engineering (MAGE), customized optimization of metabolic pathways by combinatorial transcriptional engineering (COMPACTER), and library construction of "tunable intergenic regions" (TIGR). Since combinatorial approaches and high-throughput screening methods are fundamentally interconnected, color/fluorescence-based, growth-based, and biosensor-based high-throughput screening methods have been reviewed. We believe that with the help of metabolic engineering tools and new combinatorial approaches, plus effective high-throughput screening methods, researchers will be able to achieve better results on improving microorganism performance under stress or enhancing biochemical yield.

Phytoplasma is an insect-transmitted pathogen that causes witches' broom disease in many plants. Paulownia witches' broom is one of the most destructive diseases threatening Paulownia production. The molecular mechanisms associated with this disease have been investigated by transcriptome sequencing, but changes in protein abundance have not been investigated with isobaric tags for relative and absolute quantitation. Previous results have shown that methyl methane sulfonate (MMS) can help Paulownia seedlings recover from the symptoms of witches' broom and reinstate a healthy morphology. In this study, a transcriptomic-assisted proteomic technique was used to analyze the protein changes in phytoplasma-infected Paulownia tomentosa seedlings, phytoplasma-infected seedlings treated with 20 and 60 mg·L−1 MMS, and healthy seedlings. A total of 2,051 proteins were obtained, 879 of which were found to be differentially abundant in pairwise comparisons between the sample groups. Among the differentially abundant proteins, 43 were related to Paulownia witches' broom disease and many of them were annotated to be involved in photosynthesis, expression of dwarf symptom, energy production, and cell signal pathways.

The jasmonate family of phytohormones plays central roles in plant development and stress acclimation. However, the regulatory modes of their signaling circuitry remain largely unknown. Here we describe that cyclophilin 20–3 (CYP20-3), a binding protein of (+)-12-oxo-phytodienoic acid (OPDA), crisscrosses stress responses with light-dependent redox reactions, which fine-tunes the activity of key enzymes in the plastid photosynthetic carbon assimilation and sulfur assimilation pathways. Under stressed states, OPDA – accumulated in the chloroplasts – binds and promotes CYP20-3 to transfer electron (e−) from thioredoxins (i.e. type-f2 and -x) to 2-Cys peroxiredoxin B (2-CysPrxB) or serine acetyltransferase 1 (SAT1). Reduction (activation) of 2-CysPrxB then optimizes peroxide detoxification and carbon metabolisms in the photosynthesis, whereas the activation of SAT1 stimulates sulfur assimilation which in turn coordinates redox-resolved nucleus gene expressions in defense responses against biotic and abiotic stresses. Thus, we conclude that CYP20-3 is positioned as a unique metabolic hub in the interface between photosynthesis (light) and OPDA signaling, where controls resource (e−) allocations between plant growth and defense responses.

Polyploidy events are believed to be responsible for increasing the size of plant organs and enhancing tolerance to environmental stresses. Autotetraploid Paulownia australis plants exhibit superior traits compared with their diploid progenitors. Although some transcriptomics studies have been performed and some relevant genes have been revealed, the molecular and biological mechanisms regulating the predominant characteristics and the effects of polyploidy events on P. australis remain unknown. In this study, we compared the phenotypes, microstructures, and proteomes of autotetraploid and diploid P. australis plants. Compared with the diploid plant, the leaves of the autotetraploid plant were longer and wider, and the upper epidermis, lower epidermis, and palisade layer of the leaves were thicker, the leaf spongy parenchyma layer was thinner, the leaf cell size was bigger, and cell number was lower. In the proteome analysis, 3,010 proteins were identified and quantified, including 773 differentially abundant proteins. These results may help to characterize the P. australis proteome profile. Differentially abundant proteins related to cell division, glutathione metabolism, and the synthesis of cellulose, chlorophyll, and lignin were more abundant in the autotetraploid plants. These results will help to enhance the understanding of variations caused by polyploidy events in P. australis. The quantitative real-time PCR results provided details regarding the expression patterns of the proteins at mRNA level. We observed a limited correlation between transcript and protein levels. These observations may help to clarify the molecular basis for the predominant autotetraploid characteristics and be useful for plant breeding in the future.

Additional file 1. Additional materials.

Acetyl-CoA is an important precursor in Saccharomyces cerevisiae. Various approaches have been adopted to improve its cytosolic level previously with the emphasis on engineering the “acetyl-” part of acetyl-CoA. To the best of our knowledge, there have been no reports on engineering the “-CoA” part so far. In this study, we had tried to engineer S. cerevisiae from both the “-CoA” part via pantothenate kinase overexpression (PanK from S. cerevisiae, the rate-limiting enzyme for CoA synthesis) and the “acetyl-“part through PDH bypass introduction (ALD6 from S. cerevisiae and SeAcs L641P from Salmonella enteric). A naringenin-producing reporter strain had been constructed to reflect cytosolic acetyl-CoA level as acetyl-CoA is the precursor of naringenin. It was found that PanK overexpression or PDH bypass introduction alone only led to a twofold or 6.74-fold increase in naringenin titer, but the combination of both (strain CENFPAA01) had resulted in 24.4-fold increase as compared to the control (strain CENF09) in the presence of 0.5 mM substrate p-coumaric acid. The supplement of PanK substrate pantothenate resulted in another 19% increase in naringenin production. To greatly enhance acetyl-CoA level in yeast cytosol, it is feasible to engineer both the “acetyl-” part and the “-CoA” part simultaneously. Insufficient CoA supply might aggravate acetyl-CoA shortage and cause low yield of target product.

Background Acetyl-CoA is an important precursor in Saccharomyces cerevisiae. Various approaches have been adopted to improve its cytosolic level previously with the emphasis on engineering the “acetyl-” part of acetyl-CoA. To the best of our knowledge, there have been no reports on engineering the “-CoA” part so far. Results In this study, we had tried to engineer S. cerevisiae from both the “-CoA” part via pantothenate kinase overexpression (PanK from S. cerevisiae, the rate-limiting enzyme for CoA synthesis) and the “acetyl-“part through PDH bypass introduction (ALD6 from S. cerevisiae and SeAcs L641P from Salmonella enteric). A naringenin-producing reporter strain had been constructed to reflect cytosolic acetyl-CoA level as acetyl-CoA is the precursor of naringenin. It was found that PanK overexpression or PDH bypass introduction alone only led to a twofold or 6.74-fold increase in naringenin titer, but the combination of both (strain CENFPAA01) had resulted in 24.4-fold increase as compared to the control (strain CENF09) in the presence of 0.5 mM substrate p-coumaric acid. The supplement of PanK substrate pantothenate resulted in another 19% increase in naringenin production. Conclusions To greatly enhance acetyl-CoA level in yeast cytosol, it is feasible to engineer both the “acetyl-” part and the “-CoA” part simultaneously. Insufficient CoA supply might aggravate acetyl-CoA shortage and cause low yield of target product. Electronic supplementary material The online version of this article (doi:10.1186/s13068-017-0726-z) contains supplementary material, which is available to authorized users.

Membrane fouling and concentration polarization are two of the main barriers for the application of the membrane separation technique in food industry. In order to increase membrane separation efficiency caused by membrane fouling and concentration polarization, γ-Al2O3 membrane was employed to separate bovine serum albumin (BSA) solution in the presence of an electrical field. In this paper, the influences of electric field intensity, pH of bulk solution, and operating time on membrane performance were investigated. It was found that the influence of an external electric field on the membrane process depends on the charged properties of bulk solution. For negatively charged BSA in the solution of pH 6.8, an external electric field can improve both the flux and rejection of membrane. What is more, separation process can be maintained at a quite high flux for 60 min without significant decrease in this method, and the increase of electric field intensity can improve the membrane separation efficie...

Extreme temperatures are associated with increased daily mortality in many regions of the world (Patz and Khaliq 2002). Because human activity is likely to increase overall global average temperatures, research efforts have focused on the health effects of exposure to high temperatures and heat waves in summer. In the United States, increased mortality during high-temperature days has been extensively investigated. Semenza et al. (1996) reported that a heat wave in Chicago, Illinois, in 1995 was associated with an increase in the death rate among socially isolated people who had no air conditioning. In studies of multiple U.S. cities, similar results were reported (Curriero et al. 2002). In Europe, excess mortality during high-temperature days has also been noted. Le Tertre et al. (2006) also reported an association between the 2003 heat wave in France and increases in all causes of mortality in nine French cities. Stafoggia et al. (2006) explored vulnerability to heat-related mortality in four Italian cities: Bologna, Milan, Rome, and Turin. The populations particularly vulnerable to high summer temperatures were the elderly, women, widows and widowers, those with particular medical conditions, and those in nursing homes and health care facilities. Air pollution is also associated with increased daily mortality (Pope 2000). A large number of daily mortality time-series analyses have provided sufficiently convincing evidence that nonaccidental mortality, including cardio-pulmonary mortality, is associated with ambient particulate matter (PM) exposure in the United States (Ostro et al. 2007), Canada (Burnett et al. 2000), Rome (Forastiere et al. 2007), China (Kan et al. 2007), Korea (Lee et al. 2000), Greece (Katsouyanni et al. 1997), and Chile (Cakmak et al. 2007). The estimated effect is generally in the range of 1.0–8.0% excess deaths per 50-μg/m3 increments in 24-hr average concentrations of particulate matter ≤ 10 μm in aerodynamic diameter (PM10) (Schwartz and Zanobetti 2000). Although the independent impacts of high temperature and air pollution on daily mortality have been widely explored, few studies have examined the interaction between high temperature and air pollution (Samet et al. 1998). Investigating the effects of the synergy between air pollution and high temperature on mortality, although desirable, is difficult, because a suitable study site is not easily available. The Chinese city of Wuhan, however, provides an opportunity to examine these synergistic effects; it has been called an “oven” city because of its extremely hot summers. Previous studies in Wuhan (He et al. 1993; Qian et al. 2004) have shown high air pollution levels, with concentration ranges wider than those reported in the published literature for other locations. Therefore, we tested the hypothesis that temperature extremes modify the mortality effects of air pollution.

The recently developed CRISPR/Cas9 system is a promising technology for targeted genome editing in a variety of species including plants. However, the first generation systems were designed to target one or two gene loci at a time. We designed a new multiplex CRISPR/Cas9 system that allows the co-expression of six sgRNA modules in one binary vector using a simple (three steps) cloning strategy in Arabidopsis. The transcription of the sgRNA modules is under the control of three different RNA Polymerase III-dependent promoters. We tested the efficiency of the new multiplex system by targeting six of the fourteen PYL families of ABA receptor genes in a single transformation experiment. One line with mutations in all six targeted PYLs was identified from 15 T1 plants. The mutagenesis frequency for the six individual PYL targets in the T1 lines ranged from 13 to 93 %. In the presence of ABA, the transgenic line identified as containing mutations in all six PYL genes produced the highest germination rate in the T2 progeny (37 %). Among these germinated seedlings, half of the analyzed plants (15/30) were homozygous mutants for at least four targeted genes and two plants (6.7 %) contained homozygous mutations in five of the targeted PYLs and the other targeted PYL had biallelic mutations. Homozygous sextuple mutants were identified in the T3 progeny and characterized together with previously described triple and sextuple PYL mutants. We anticipate that the application of this multiplex CRISPR/Cas9 system will strongly facilitate functional analysis of genes pathways and families.

DNA methylation is a conserved epigenetic mark that plays important roles in plant and vertebrate development, genome stability, and gene regulation. Canonical Methyl-CpG-binding domain (MBD) proteins are important interpreters of DNA methylation that recognize methylated CG sites and recruit chromatin remodelers, histone deacetylases, and histone methyltransferases to repress transcription. Here, we show that Arabidopsis MBD7 and Increased DNA Methylation 3 (IDM3) are anti-silencing factors that prevent gene repression and DNA hypermethylation. MBD7 preferentially binds to highly methylated, CG-dense regions and physically associates with other anti-silencing factors, including the histone acetyltransferase IDM1 and the alpha-crystallin domain proteins IDM2 and IDM3. IDM1 and IDM2 were previously shown to facilitate active DNA demethylation by the 5-methylcytosine DNA glycosylase/lyase ROS1. Thus, MBD7 tethers the IDM proteins to methylated DNA, which enables the function of DNA demethylases that in turn limit DNA methylation and prevent transcriptional gene silencing.

Coexistent amorphous and nanoscale bcc-Mg7Li3 phases were found in slowly quenched alloys of the Mg65–xLixCu25Y10 system containing 3 to 15 at. % Li. The crystallization behavior of these alloys has been studied. The grain size of the nanocrystalline bcc phase which is formed ranges from 2 to 20 nm. The volume fraction of nanocrystalline phases as well as the grain size of the nanocrystals increase as the Li composition increases. Transmission electron microscopy studies suggest that the alloy exhibits phase separation in the undercooled liquid state and that the nucleation and growth of the bcc-nanocrystals is related to the phase separation. Some characteristic thermal properties of the glassy phase are presented, and the composition dependence of Tg and Tx is discussed. It is concluded that the addition of a small amount of Li is essential for the production of a bcc nanocrystalline phase in the Mg–Li–Cu–Y system.

Nanotechnology-inspired biocatalysts have aroused much interest recently because nanomaterials can provide the upper limits on enzyme-efficiency-determining factors. Non-specific immobilization approaches often face problems of enzyme leaching, 3D structure change and mass transfer resistance. Here, we focus on the review of specific enzyme immobilization approaches and have separated them into non-covalent and covalent categories.

Fewer studies have been published on the association between daily mortality and ambient air pollution in Asia than in the United States and Europe. This study was undertaken in Wuhan, China, to investigate the acute effects of air pollution on mortality with an emphasis on particulate matter (PM*). There were three primary aims: (1) to examine the associations of daily mortality due to all natural causes and daily cause-specific mortality (cardiovascular [CVD], stroke, cardiac [CARD], respiratory [RD], cardiopulmonary [CP], and non-cardiopulmonary [non-CP] causes) with daily mean concentrations (microg/m3) of PM with an aerodynamic diameter--10 pm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), or ozone (O3); (2) to investigate the effect modification of extremely high temperature on the association between air pollution and daily mortality due to all natural causes and daily cause-specific mortality; and (3) to assess the uncertainty of effect estimates caused by the change in International Classification of Disease (ICD) coding of mortality data from Revision 9 (ICD-9) to Revision 10 (ICD-10) code. Wuhan is called an "oven city" in China because of its extremely hot summers (the average daily temperature in July is 37.2 degrees C and maximum daily temperature often exceeds 40 degrees C). Approximately 4.5 million residents live in the core city area of 201 km2, where air pollution levels are higher and ranges are wider than the levels in most cities studied in the published literature. We obtained daily mean levels of PM10, SO2, and NO2 concentrations from five fixed-site air monitoring stations operated by the Wuhan Environmental Monitoring Center (WEMC). O3 data were obtained from two stations, and 8-hour averages, from 10:00 to 18:00, were used. Daily mortality data were obtained from the Wuhan Centres for Disease Prevention and Control (WCDC) during the study period of July 1, 2000, to June 30, 2004. To achieve the first aim, we used a regression of the logarithm of daily counts of mortality due to all natural causes and cause-specific mortality on the daily mean concentrations of the four pollutants while controlling for weather, temporal factors, and other important covariates with generalized additive models (GAMs). We derived pollutant effect estimations for 0-day, 1-day, 2-day, 3-day, and 4-day lagged exposure levels, and the averages of 0-day and 1-day lags (lag 0-1 day) and of 0-day, 1-day, 2-day, and 3-day lags (lag 0-3 days) before the event of death. In addition, we used individual-level data (e.g., age and sex) to classify subgroups in stratified analyses. Furthermore, we explored the nonlinear shapes ("thresholds") of the exposure-response relations. To achieve the second aim, we tested the hypothesis that extremely high temperature modifies the associations between air pollution and daily mortality. We developed three corresponding weather indicators: "extremely hot," "extremely cold," and "normal temperatures." The estimates were obtained from the models for the main effects and for the pollutant-temperature interaction for each pollutant and each cause of mortality. To achieve the third aim, we conducted an additional analysis. We examined the concordance rates and kappa statistics between the ICD-9-coded mortality data and the ICD-10-coded mortality data for the year 2002. We also compared the magnitudes of the estimated effects resulting from the use of the two types of ICD-coded mortality data. In general, the largest pollutant effects were observed at lag 0-1 day. Therefore, for this report, we focused on the results obtained from the lag 0-1 models. We observed consistent associations between PM10 and mortality: every 10-microg/m3 increase in PM10 daily concentration at lag 0-1 day produced a statistically significant association with an increase in mortality due to all natural causes (0.43%; 95% confidence interval [CI], 0.24 to 0.62), CVD (0.57%; 95% CI, 0.31 to 0.84), stroke (0.57%; 95% CI, 0.25 to 0.88), CARD (0.49%; 95% CI, 0.04 to 0.94), RD (0.87%; 95% CI, 0.34 to 1.41), CP (0.52%; 95% CI, 0.27 to 0.77), and non-CP (0.30%; 95% CI, 0.05 to 0.54). In general, these effects were stronger in females than in males and were also stronger among the elderly (or = 65 years) than among the young. The results of sensitivity testing over the range of exposures from 24.8 to 477.8 microg/m3 also suggest the appropriateness of assuming a linear relation between daily mortality and PM10. Among the gaseous pollutants, we also observed statistically significant associations of mortality with NO, and SO2, and that the estimated effects of these two pollutants were stronger than the PM10 effects. The patterns of NO2 and SO2 associations were similar to those of PM10 in terms of sex, age, and linearity. O3 was not associated with mortality. In the analysis of the effect modification of extremely high temperature on the association between air pollution and daily mortality, only the interaction of PM10 with temperature was statistically significant. Specifically, the interaction terms were statistically significant for mortality due to all natural (P = 0.014), CVD (P = 0.007), and CP (P = 0.014) causes. Across the three temperature groups, the strongest PM10 effects occurred mainly on days with extremely high temperatures for mortality due to all natural (2.20%; 95% CI, 0.74 to 3.68), CVD (3.28%; 95% CI, 1.24 to 5.37), and CP (3.02%; 95% CI, 1.03 to 5.04) causes. The weakest effects occurred at normal temperature days, with the effects on days with low temperatures in the middle. To assess the uncertainty of the effect estimates caused by the change from ICD-9-coded mortality data to ICD-10-coded mortality data, we compared the two sets of data and found high concordance rates (99.3%) and kappa statistics close to 1.0 (0.98). All effect estimates showed very little change. All statistically significant levels of the estimated effects remained unchanged. In conclusion, the findings for the aims from the current study are consistent with those in most previous studies of air pollution and mortality. The small differences between mortality effects for deaths coded using ICD-9 and ICD-10 show that the change in coding had a minimal impact on our study. Few published papers have reported synergistic effects of extremely high temperatures and air pollution on mortality, and further studies are needed. Establishing causal links between heat, PM10, and mortality will require further toxicologic and cohort studies.

Lipase has been used widely in industry. In this study, we have constructed two recombinant Saccharomyces cerevisiae strains displaying two active lipases on the cell surface by cell surface engineering. The genes encoding Yarrowia lipolytica lipases Lip7 and Lip8 were fused with the gene encoding small binding subunit Aga2 of a-agglutinin. Localization of the Lip7 and Lip8 on the cell surface was confirmed by immunofluorescence microscopy. Besides, the putative signal sequences of Lip7 and Lip8 were removed to compare their effect on the activities of surface-displayed lipases. The results showed that the activities towards p-nitrophenyl caprylate of surface-displayed Lip7 and Lip8 were 283 U/g (dry cell) and 121 U/g (dry cell), much higher than that using Flo1 as anchor protein in Pichia pastoris, and the putative signal sequences have significant effect on the activities of the displayed lipases; when deleted, the lipases’ activities were declined to 65 U/g (dry cell) and 80 U/g (dry cell), respectively. The displayed lipases exhibit a preference for middle chain fatty acids and a high thermal stability. Additionally, from the study, to surface-display a target protein, it is recommendable that the structure feature of the protein should be assayed through bioinformatics methods and then the cell wall proteins with the anchor domain far away from the activity center should be chosen as anchor proteins.

Red recombinase system of the lambda phage is widely used for recombination of short linear DNA fragments and genome. Using this system, we obtained T7 RNA polymerase (RNAP) substitution mutants in Burkholderia cepacia. To test the expression abilities of the T7 mutants, four different lipase expression vectors were transformed and the lipase activity of these recombinants was evaluated. Our results suggest that 500 nt homology between the unit and the genome is sufficient to generate mutations and this strategy enables the rapid establishment of mutant strains with efficiencies of 85%. After expression and purification, the highest purified lipase activity obtained was 3,990 U/l, nearly triple that of the wild-type organism.

Lipase Lip2 from Yarrowia lipolytica was displayed on the cell surface of Saccharomyces cerevisiae using Cwp2 as an anchor protein. Successful display of the lipase on the cell surface was confirmed by immunofluorescence microscopy and halo assay. The length of linker sequences was further examined to confirm that the correct conformation of Lip2 was maintained. The results showed that the displayed Lip2 exhibited the highest activity at 7.6 +/- 0.4 U/g (dry cell) when using (G(4)S)(3) sequence as the linker, with an optimal temperature and pH at 40 degrees C and pH 8.0. The displayed lipase did not lose any activity after being treated with 0.1% Triton X-100 and 0.1% Tween 80 for 30 min, and it retained 92% of its original activity after incubation in 10% DMSO for 30 min. It also exhibited better thermostability than free Lip2 as reported previously.