Microbial production of O-methylated flavanones from methylated phenylpropanoic acids in engineered Escherichia coli

Journal of Industrial Microbiology & Biotechnology - Methylated flavonoids possess improved bioactivities compared to their unmethylated counterparts. In this study, for the efficient...     

Fruit and vegetable consumption,cardiovascular disease,and all-cause mortality in China

Science China Life Sciences - Evidence about the response patterns of fruit and vegetable consumption with the risk of cardiovascular disease (CVD) and all-cause mortality was inconsistent. These...     

Effects of 5-aminolevulinic acid on the inflammatory responses and antioxidative capacity in broiler chickens challenged with lipopolysaccharide

5-Aminolevulinic acid (5-ALA) is an intermediate in haem biosynthesis and has anti-apoptotic, anti-inflammatory, antioxidant, and other pharmacological effects. This study aimed to investigate the effect of dietary supplementation with 5-ALA on growth performance, antioxidant capacity, and inflammatory response of the lipopolysaccharide (LPS)-challenged broiler chickens. The experiment was designed as a 2 × 2 factorial arrangement with dietary 5-ALA (0 or 60 mg/kg) and LPS (injection of saline or 0.5 mg/kg BW) levels as treatments. A total of 240 one-day-old Arbor Acres broilers were distributed into four treatments consisting of six replicates of 10 birds. All the experimental broilers were intraperitoneally injected with LPS or sterile saline at 16, 18, and 20 days of age. Our results showed that dietary 5-ALA supplementation reduced (P < 0.05) the feed to gain before broilers were stimulated with LPS (days 1–15). LPS challenge decreased (P < 0.05) the catalase (CAT), total superoxide dismutase activities and increased the content of malondialdehyde (MDA) in the serum of broiler chickens. However, 5-ALA supplementation had a tendency to increase (P = 0.08) the activity of CAT and decreased (P < 0.05) the content of MDA. LPS challenge showed higher (P < 0.05) interleukin (IL)-1β, IL-6, and IL-10 concentrations in the serum, whereas dietary 5-ALA supplementation decreased (P < 0.05) the levels of IL-1β and IL-6. Additionally, dietary 5-ALA supplementation significantly attenuated (P < 0.05) the upregulation of mRNA expression levels of hepatic toll-like receptor 4 (TLR4), IL-1β, and IL-2 induced by LPS challenge. Moreover, dietary 5-ALA supplementation also enhanced the mRNA expression of 5-aminolevulinate dehydratase, ferrochelatase, and haem oxygenase-1 (HO-1) as compared to the unsupplemented groups. In conclusion, our results suggested that supplementation of 60 mg/kg 5-ALA exhibited LPS-induced anti-inflammatory and antioxidant properties by enhancing the HO-1 expression and inhibiting the TLR4/NF-κB signalling pathway.     

Evolutionary flexibility of pair-rule patterning revealed by functional analysis of secondary pair-rule genes, paired and sloppy-paired in the short-germ insect, Tribolium castaneum

In the Drosophila segmentation hierarchy, periodic expression of pair-rule genes translates gradients of regional information from maternal and gap genes into the segmental expression of segment polarity genes. In Tribolium, homologs of almost all the eight canonical Drosophila pair-rule genes are expressed in pair-rule domains, but only five have pair-rule functions. even-skipped, runt and odd-skipped act as primary pair-rule genes, while the functions of paired (prd) and sloppy-paired (slp) are secondary. Since secondary pair-rule genes directly regulate segment polarity genes in Drosophila, we analyzed Tc-prd and Tc-slp to determine the extent to which this paradigm is conserved in Tribolium. We found that the role of prd is conserved between Drosophila and Tribolium; it is required in both insects to activate engrailed in odd-numbered parasegments and wingless (wg) in even-numbered parasegments. Similarly, slp is required to activate wg in alternate parasegments and to maintain the remaining wg stripes in both insects. However, the parasegmental register for Tc-slp is opposite that of Drosophila slp1. Thus, while prd is functionally conserved, the fact that the register of slp function has evolved differently in the lineages leading to Drosophila and Tribolium reveals an unprecedented flexibility in pair-rule patterning.     

Structure-based design, synthesis, evaluation, and crystal structures of transition state analogue inhibitors of inosine monophosphate cyclohydrolase

The inosine monophosphate cyclohydrolase (IMPCH) component (residues 1-199) of the bifunctional enzyme aminoimidazole-4-carboxamide ribonucleotide transformylase (AICAR Tfase, residues 200-593)/IMPCH (ATIC) catalyzes the final step in the de novo purine biosynthesis pathway that produces IMP. As a potential target for antineoplastic intervention, we designed IMPCH inhibitors, 1,5-dihydroimidazo[4,5-c][1,2,6]thiadiazin-4(3H)-one 2,2-dioxide (heterocycle, 1), the corresponding nucleoside (2), and the nucleoside monophosphate (nucleotide) (3), as mimics of the tetrahedral intermediate in the cyclization reaction. All compounds are competitive inhibitors against IMPCH (K(i) values = 0.13-0.23 microm) with the simple heterocycle 1 exhibiting the most potent inhibition (K(i) = 0.13 microm). Crystal structures of bifunctional ATIC in complex with nucleoside 2 and nucleotide 3 revealed IMPCH binding modes similar to that of the IMPCH feedback inhibitor, xanthosine 5'-monophosphate. Surprisingly, the simpler heterocycle 1 had a completely different IMPCH binding mode and was relocated to the phosphate binding pocket that was identified from previous xanthosine 5'-monophosphate structures. The aromatic imidazole ring interacts with a helix dipole, similar to the interaction with the phosphate moiety of 3. The crystal structures not only revealed the mechanism of inhibition of these compounds, but they now serve as a platform for future inhibitor improvements. Importantly, the nucleoside-complexed structure supports the notion that inhibitors lacking a negatively charged phosphate can still inhibit IMPCH activity with comparable potency to phosphate-containing inhibitors. Provocatively, the nucleotide inhibitor 3 also binds to the AICAR Tfase domain of ATIC, which now provides a lead compound for the design of inhibitors that simultaneously target both active sites of this bifunctional enzyme.     

植物开花的组蛋白甲基化调控分子机理

开花是指植物从营养生长转变到生殖生长的生理过程, 是植物个体发育和后代繁衍的中心环节, 既受遗传基础决定,同时又受到温度和光周期等多种环境因素的调控。在拟南芥中, 已经分离了大量的与开花相关的基因, 从遗传学上已初步形成了一个开花调控的网络。组蛋白甲基化是植物发育过程的重要调节方式, 近年来关于其参与开花调控的研究有了重要进展。本文综述了具有代表性的组蛋白H3赖氨酸甲基化修饰参与调控植物开花发育的机制, 提出该研究领域的发展方向和前景。     

ARF-GTPase as a Molecular Switch for Polar Auxin Transport Mediated by Vesicle Trafficking in Root Development

Polar auxin transport (PAT), which is controlled precisely by both auxin efflux and influx facilitators and mediated by the cell trafficking system, modulates organogenesis, development and root gravitropism. ADP-ribosylation factor (ARF)-GTPase protein is catalyzed to switch to the GTP-bound type by a guanine nucleotide exchange factor (GEF) and promoted for hybridization to the GDP-bound type by a GTPase-activating protein (GAP). Previous studies showed that auxin efflux facilitators such as PIN1 are regulated by GNOM, an ARF-GEF, in Arabidopsis. In the November issue of The Plant Journal, we reported that the auxin influx facilitator AUX1 was regulated by ARF-GAP via the vesicle trafficking system.¹ In this addendum, we report that overexpression of OsAGAP leads to enhanced root gravitropism and propose a new model of PAT regulation: a loop mechanism between ARF-GAP and GEF mediated by vesicle trafficking to regulate PAT at influx and efflux facilitators, thus controlling root development in plants.Key Words: ADP-ribosylation factor (ARF), ARF-GAP, ARF-GEF, auxin, GNOM, polar transport of auxinPolar auxin transport (PAT) is a unique process in plants. It results in alteration of auxin level, which controls organogenesis and development and a series of physiological processes, such as vascular differentiation, apical dominance, and tropic growth.² Genetic and physiological studies identified that PAT depends on efflux facilitators such as PIN family proteins and influx facilitators such as AUX1 in Arabidopsis.Eight PIN family proteins, AtPIN1 to AtPIN8, exist in Arabidopsis. AtPIN1 is located at the basal side of the plasma membrane in vascular tissues but is weak in cortical tissues, which supports the hypothesis of chemical pervasion.³ AtPIN2 is localized at the apical side of epidermal cells and basally in cortical cells.^1,4 GNOM, an ARF GEF, modulates the localization of PIN1 and vesicle trafficking and affects root development.^5,6 The PIN auxin-efflux facilitator network controls root growth and patterning in Arabidopsis.⁴ As well, asymmetric localization of AUX1 occurs in the root cells of Arabidopsis plants,⁷ and overexpression of OsAGAP interferes with localization of AUX1.¹ Our data support that ARF-GAP mediates auxin influx and auxin-dependent root growth and patterning, which involves vesicle trafficking.¹ Here we show that OsAGAP overexpression leads to enhanced gravitropic response in transgenic rice plants. We propose a model whereby ARF GTPase is a molecular switch to control PAT and root growth and development.Overexpression of OsAGAP led to reduced growth in primary or adventitious roots of rice as compared with wild-type rice.¹ Gravitropism assay revealed transgenic rice overxpressing OsAGAP with a faster response to gravity than the wild type during 24-h treatment. However, 1-naphthyl acetic acid (NAA) treatment promoted the gravitropic response of the wild type, with no difference in response between the OsAGAP transgenic plants and the wild type plants (Fig. 1). The phenotype of enhanced gravitropic response in the transgenic plants was similar to that in the mutants atmdr1-100 and atmdr1-100/atpgp1-100 related to Arabidopsis ABC (ATP-binding cassette) transporter and defective in PAT.⁸ The physiological data, as well as data on localization of auxin transport facilitators, support ARF-GAP modulating PAT via regulating the location of the auxin influx facilitator AUX1.¹ So the alteration in gravitropic response in the OsAGAP transgenic plants was explained by a defect in PAT.Open in a separate windowFigure 1Gravitropism of OsAGAP overexpressing transgenic rice roots and response to 1-naphthyl acetic acid (NAA). (A) Gravitropism phenotype of wild type (WT) and OsAGAP overexpressing roots at 6 hr gravi-stimulation (top panel) and 0 hr as a treatment control (bottom panel). (B) Time course of gravitropic response in transgenic roots. (C and D) results correspond to those in (A and B), except for treatment with NAA (5 × 10⁻⁷ M).The polarity of auxin transport is controlled by the asymmetric distribution of auxin transport proteins, efflux facilitators and influx carriers. ARF GTPase is a key member in vesicle trafficking system and modulates cell polarity and PAT in plants. Thus, ARF-GDP or GTP bound with GEF or GAP determines the ARF function on auxin efflux facilitators (such as PIN1) or influx ones (such as AUX1).ARF1, targeting ROP2 and PIN2, affects epidermal cell polarity.⁹ GNOM is involved in the regulation of PIN1 asymmetric localization in cells and its related function in organogenesis and development.⁶ Although VAN3, an ARF-GAP in Arabidopsis, is located in a subpopulation of the trans-Golgi transport network (TGN), which is involved in leaf vascular network formation, it does not affect PAT.¹⁰ OsAGAP possesses an ARF GTPase-activating function in rice.¹¹ Specifically, our evidence supports that ARF-GAP bound with ARF-GTP modulates PAT and gravitropism via AUX1, mediated by vesicle trafficking, including the Golgi stack.¹Therefore, we propose a loop mechanism between ARF-GAP and GEF mediated by the vascular trafficking system in regulating PAT at influx and efflux facilitators, which controls root development and gravitropism in plants (Fig. 2). Here we emphasize that ARF-GEF catalyzes a conversion of ARF-bound GDP to GTP, which is necessary for the efficient delivery of the vesicle to the target membrane.¹² An opposite process of ARF-bound GDP to GTP is promoted by ARF-GTPase-activating protein via binding. A loop status of ARF-GTP and ARF-GDP bound with their appurtenances controls different auxin facilitators and regulates root development and gravitropism.Open in a separate windowFigure 2Model for ARF GTPase as a molecular switch for the polar auxin transport mediated by the vesicle traffic system.     

脑血管内皮细胞敲除Prmt5导致脑血管损伤及星形胶质细胞活化*

目的: 研究蛋白质精氨酸甲基转移酶5(protein arginine methyltransferase 5,Prmt5)在小鼠脑血管发育、稳态维持中的功能,并考察脑血管内皮细胞特异性敲除Prmt5后对中枢神经系统的影响。方法: 利用脑血管内皮细胞特异性表达SP-A-Cre转基因小鼠和Prmt5条件基因打靶小鼠交配,构建脑血管内皮细胞特异性Prmt5敲除小鼠。利用H-E染色、免疫荧光染色、激光散斑成像、Sulfo-NHS-Biotin染料灌注等方法评价脑血管内皮细胞特异性Prmt5敲除小鼠脑血管结构、脑血流量、血脑屏障渗透性等;利用实时定量PCR进一步检测补体C1q(complement C1q,C1q)、肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)和白细胞介素-1β(interleukin 1β,IL-1β)等细胞因子的表达水平。通过免疫荧光、Western blot等检测胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)、S100钙结合蛋白β(S100 calcium-binding protein β protein,S100β)和补体C3(complement C3,C3)的表达,检测小鼠皮层、丘脑和小脑中星形胶质细胞活化水平。结果: 脑血管内皮细胞特异性敲除Prmt5导致血管损伤, C1q、TNF-α和IL-1β等炎症因子表达水平上调,活化星形胶质细胞比例明显增加。结论: 脑血管内皮细胞中Prmt5在小鼠脑血管稳态维持中发挥了重要功能。     

An integrated fluid–structure interaction and thrombosis model for type B aortic dissection

False lumen thrombosis (FLT) in type B aortic dissection has been associated with the progression of dissection and treatment outcome. Existing computational models mostly assume rigid wall behavior which ignores the effect of flap motion on flow and thrombus formation within the FL. In this study, we have combined a fully coupled fluid–structure interaction (FSI) approach with a shear-driven thrombosis model described by a series of convection–diffusion reaction equations. The integrated FSI-thrombosis model has been applied to an idealized dissection geometry to investigate the interaction between vessel wall motion and growing thrombus. Our simulation results show that wall compliance and flap motion can influence the progression of FLT. The main difference between the rigid and FSI models is the continuous development of vortices near the tears caused by drastic flap motion up to 4.45 mm. Flap-induced high shear stress and shear rates around tears help to transport activated platelets further to the neighboring region, thus speeding up thrombus formation during the accelerated phase in the FSI models. Reducing flap mobility by increasing the Young’s modulus of the flap slows down the thrombus growth. Compared to the rigid model, the predicted thrombus volume is 25% larger using the FSI-thrombosis model with a relatively mobile flap. Furthermore, our FSI-thrombosis model can capture the gradual effect of thrombus growth on the flow field, leading to flow obstruction in the FL, increased blood viscosity and reduced flap motion. This model is a step closer toward simulating realistic thrombus growth in aortic dissection, by taking into account the effect of intimal flap and vessel wall motion.