RESUMO
Chlorophyll degradation and anthocyanin biosynthesis, which often occur almost synchronously during fruit ripening, are crucial for vibrant coloration of fruits. However, the interlink point between their regulatory pathways remains largely unknown. Here, 2 litchi (Litchi chinensis Sonn.) cultivars with distinctively different coloration patterns during ripening, i.e. slow-reddening/stay-green "Feizixiao" (FZX) vs rapid-reddening/degreening "Nuomici" (NMC), were selected as the materials to study the key factors determining coloration. Litchi chinensis STAY-GREEN (LcSGR) was confirmed as the critical gene in pericarp chlorophyll loss and chloroplast breakdown during fruit ripening, as LcSGR directly interacted with pheophorbide a oxygenase (PAO), a key enzyme in chlorophyll degradation via the PAO pathway. Litchi chinensis no apical meristem (NAM), Arabidopsis transcription activation factor 1/2, and cup-shaped cotyledon 2 (LcNAC002) was identified as a positive regulator in the coloration of litchi pericarp. The expression of LcNAC002 was significantly higher in NMC than in FZX. Virus-induced gene silencing of LcNAC002 significantly decreased the expression of LcSGR as well as L. chinensis MYELOBLASTOSIS1 (LcMYB1), and inhibited chlorophyll loss and anthocyanin accumulation. A dual-luciferase reporter assay revealed that LcNAC002 significantly activates the expression of both LcSGR and LcMYB1. Furthermore, yeast-one-hybrid and electrophoretic mobility shift assay results showed that LcNAC002 directly binds to the promoters of LcSGR and LcMYB1. These findings suggest that LcNAC002 is an important ripening-related transcription factor that interlinks chlorophyll degradation and anthocyanin biosynthesis by coactivating the expression of both LcSGR and LcMYB1.
Assuntos
Antocianinas , Litchi , Antocianinas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Litchi/genética , Frutas/genética , Regulação da Expressão Gênica de Plantas , Clorofila/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
In flowering plants, floral induction signals intersect at the shoot apex to modulate meristem determinacy and growth form. Here, we report a single-nucleus RNA sequence analysis of litchi apical buds at different developmental stages. A total of 41â 641 nuclei expressing 21â 402 genes were analyzed, revealing 35 cell clusters corresponding to 12 broad populations. We identify genes associated with floral transition and propose a model that profiles the key events associated with litchi floral meristem identity by analyzing 567 identified floral meristem cells at single cell resolution. Interestingly, single-nucleus RNA-sequencing data indicated that all putative FT and TFL1 genes were not expressed in bud nuclei, but significant expression was detected in bud samples by RT-PCR. Based on the expression patterns and gene silencing results, we highlight the critical role of LcTFL1-2 in inhibiting flowering and propose that the LcFT1/LcTFL1-2 expression ratio may determine the success of floral transition. In addition, the transport of LcFT1 and LcTFL1-2 mRNA from the leaf to the shoot apical meristem is proposed based on in situ and dot-blot hybridization results. These findings allow a more comprehensive understanding of the molecular events during the litchi floral transition, as well as the identification of new regulators.
Assuntos
Flores , Litchi , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Folhas de Planta/metabolismo , Análise de Sequência de RNA/métodos , Meristema , Regulação da Expressão Gênica de PlantasRESUMO
Elucidating the biochemical and molecular basis of premature abscission in fruit crops should help develop strategies to enhance fruit set and yield. Here, we report that LcERF2 contributes to differential abscission rates and responses to ethylene in Litchi chinensis (litchi). Reduced LcERF2 expression in litchi was observed to reduce fruit abscission, concurrent with enhanced pedicel growth and increased levels of hexoses, particularly galactose, as well as pectin abundance in the cell wall. Ecoptic expression of LcERF2 in Arabidopsis thaliana caused enhanced petal abscission, together with retarded plant growth and reduced pedicel galactose and pectin contents. Transcriptome analysis indicated that LcERF2 modulates the expression of genes involved in cell wall modification. Yeast one-hybrid, dual-luciferase reporter and electrophoretic mobility shift assays all demonstrated that a UDP-glucose-4-epimerase gene (LcUGE) was the direct downstream target of LcERF2. This result was further supported by a significant reduction in the expression of the A. thaliana homolog AtUGE2-4 in response to LcERF2 overexpression. Significantly reduced pedicel diameter and enhanced litchi fruit abscission were observed in response to LcUGE silencing. We conclude that LcERF2 mediates fruit abscission by orchestrating cell wall metabolism, and thus pedicel growth, in part by repressing the expression of LcUGE.
Assuntos
Parede Celular/metabolismo , Frutas/metabolismo , Litchi/metabolismo , Proteínas de Plantas/metabolismo , UDPglucose 4-Epimerase/metabolismo , Arabidopsis , Ensaio de Desvio de Mobilidade Eletroforética , Frutas/enzimologia , Frutas/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Genes de Plantas/genética , Litchi/enzimologia , Litchi/crescimento & desenvolvimento , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , UDPglucose 4-Epimerase/genéticaRESUMO
BACKGROUND: Maturation of litchi (Litchi chinensis) fruit is characterized by dramatic changes in pigments in the pericarp and flavor compounds in the aril. Among them, the biosynthesis of anthocyanins is most noticeable. Previous studies showed that LcMYB1 and LcbHLH transcription factors participated in regulating the anthocyanin biosynthesis in litchi. However, the roles of other MYB factors remain unclear. RESULTS: In this study, we cloned and characterized the function of LcMYB5, a novel R2R3-MYB identified from litchi transcriptome. Although LcMYB5 was constitutively expressed in litchi tissues and its expressions was not correlated with tissue coloration, overexpression of LcMYB5 resulted in enhanced biosynthesis of anthocyanins in tobacco and petunia concurrent with the up-regulation of their endogenous bHLHs and key structural genes in anthocyanin precursor biosynthesis. These results indicate that LcMYB5 is an R2R3 transcriptional factor regulates anthocyanin biosynthesis either by directly activating the expression of key structural genes such as DFR or by indirectly up regulating the expressions of endogenous bHLH regulators. More interestingly, the pH values in petals and leaves from transgenic lines were significant lower than those in both untransformed tobacco and petunia, indicating LcMYB5 is also associated with pH regulation. The expressions of LcMYB5 and its bHLH partner LcbHLH1 were consistent with the expression of putative tissue acidification gene LcPH1, and the changes in malic acid provided further evidence for the close relationship between LcMYB5 and tissue acidification. CONCLUSIONS: Taking together, our study indicated that LcMYB5 is involved in not only anthocyanin biosynthesis but also tissue acidification.
Assuntos
Antocianinas/metabolismo , Litchi/metabolismo , Fatores de Transcrição/metabolismo , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Litchi/genética , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/genéticaRESUMO
Although methylated cyclitols constitute a major proportion of the carbohydrates in many plant species, their physiological roles and biosynthetic pathway are largely unknown. Quebrachitol (2-O-methyl-chiro-inositol) is one of the major methylated cyclitols in some plant species. In litchi, quebrachitol represents approximately 50% of soluble sugars in mature leaves and 40% of the total sugars in phloem exudate. In the present study, we identified bornesitol as a transient methylated intermediate of quebrachitol and measured the concentrations of methyl-inositols in different tissues and in tissues subjected to different treatments. 14CO2 feeding and phloem exudate experiments demonstrated that quebrachitol is one of the transportable photosynthates. In contrast to other plant species, the biosynthesis of quebrachitol in litchi is not associated with osmotic stress. High quebrachitol concentrations in tissues of the woody plant litchi might represent a unique carbon metabolic strategy that maintains osmolality under reduced-sucrose conditions. The presence of bornesitol but not ononitol in the leaves indicates a different biosynthetic pathway with pinitol. The biosynthesis of quebrachitol involves the methylation of myo-inositol and the subsequent epimerization of bornesitol. An inositol methyltransferase gene (LcIMT1) responsible for bornesitol biosynthesis was isolated and characterized for the first time, and the biosynthesis pathways of methyl-inositols are discussed.
Assuntos
Inositol/análogos & derivados , Litchi/metabolismo , Floema/fisiologia , Transporte Biológico , Inositol/biossíntese , Litchi/química , Metilação , Metiltransferases/genética , Metiltransferases/metabolismo , Pressão Osmótica , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
Anthocyanins generate the red color in the pericarp of Litchi chinensis. UDP-glucose: flavonoid 3-O-glycosyltransferase (UFGT, EC. 2.4.1.91) stabilizes anthocyanidin by attaching sugar moieties to the anthocyanin aglycone. In this study, the function of an UFGT gene involved in the biosynthesis of anthocyanin was verified through heterologous expression and virus-induced gene silencing assays. A strong positive correlation between UFGT activity and anthocyanin accumulation capacity was observed in the pericarp of 15 cultivars. Four putative flavonoid 3-O-glycosyltransferase-like genes, designated as LcUFGT1 to LcUFGT4, were identified in the pericarp of litchi. Among the four UFGT gene members, only LcUFGT1 can use cyanidin as its substrate. The expression of LcUFGT1 was parallel with developmental anthocyanin accumulation, and the heterologously expressed protein of LcUFGT1 displayed catalytic activities in the formation of anthocyanin. The LcUFGT1 over-expression tobacco had darker petals and pigmented filaments and calyxes resulting from higher anthocyanin accumulations compared with non-transformed tobacco. In the pericarp with LcUFGT1 suppressed by virus-induced gene silencing, pigmentation was retarded, which was well correlated with the reduced-LcUFGT1 transcriptional activity. These results suggested that the glycosylation-related gene LcUFGT1 plays a critical role in red color formation in the pericarp of litchi.
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The available components in the flesh of litchi seem insufficient to interpret its wide and significant physiological effects. Some unusual compounds, including myo-inositol, inositol methyl derivatives and γ-aminobutyric acid (GABA) were identified as main constituents in the flesh of litchi. Their concentrations varied among cultivars but remain relatively constant during development. Litchi flesh was shown to contain moderate myo-inositol (0.28-0.78 mg g(-1) FW), ascorbic acid (0.08-0.39 mg g(-1) FW) and phenolics (0.47-1.60 mg g(-1) FW), but abundant l-quebrachitol (1.6-6.4 mg g(-1) FW) and GABA (1.7-3.5 mg g(-1) FW). The concentration of GABA in the flesh of litchi was about 100 times higher than in other fruits. And l-quebrachitol is not a common component in fruits. The biological and physiological activities of inositols, inositol derivatives and GABA have been extensively documented. These compounds are probably important compositional characteristic contributing to the widely shown health benefits of litchi.
Assuntos
Inositol/análogos & derivados , Litchi/química , Ácido gama-Aminobutírico/análise , Aminoácidos/análise , Ácido Ascórbico/análise , Flavonoides/análise , Frutas/química , Inositol/análise , Fenóis/análiseRESUMO
The post-phloem unloading pathway and the mechanism of sugar accumulation remain unclear in litchi fruit. A combination of electron microscopy, transport of phloem-mobile symplasmic tracer (carboxyfluorescein, CF) and biochemical and molecular assays was used to explore the post-phloem transport pathway and the mechanism of aril sugar accumulation in litchi. In the funicle, where the aril originates, abundant plasmodesmata were observed, and CF introduced from the peduncle diffused to the parenchyma cells. In addition, abundant starch and pentasaccharide were detected and the sugar concentration was positively correlated with activities of sucrose hydrolysis enzymes. These results clearly showed that the phloem unloading and post-phloem transport in the funicle were symplastic. On the other hand, imaging of CF showed that it remained confined to the parenchyma cells in funicle tissues connecting the aril. Infiltration of both an ATPase inhibitor [eosin B (EB)] and a sucrose transporter inhibitor [p-chloromercuribenzene sulfonate (PCMBS)] inhibited sugar accumulation in the aril. These results indicated an apoplasmic post-phloem sugar transport from the funicle to the aril. Although facilitated diffusion might help sucrose uptake from the cytosol to the vacuole in cultivars with high soluble invertase, membrane ATPases in the aril, especially tonoplast ATPase, are crucial for aril sugar accumulation. The expression of a putative aril vacuolar membrane sucrose transporter gene (LcSUT4) was highly correlated with the sugar accumulation in the aril of litchi. These data suggest that apoplasmic transport is critical for sugar accumulation in litchi aril and that LcSUT4 is involved in this step.
Assuntos
Metabolismo dos Carboidratos , Frutas/metabolismo , Litchi/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Floema/metabolismo , Proteínas de Plantas/metabolismo , Bombas de Próton/metabolismo , 4-Cloromercuriobenzenossulfonato/farmacologia , Transporte Biológico/efeitos dos fármacos , Metabolismo dos Carboidratos/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Azul de Eosina I/farmacologia , Fluoresceínas/metabolismo , Frutas/genética , Frutas/crescimento & desenvolvimento , Frutas/ultraestrutura , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Litchi/efeitos dos fármacos , Litchi/genética , Litchi/ultraestrutura , Proteínas de Membrana Transportadoras/genética , Floema/efeitos dos fármacos , Floema/ultraestrutura , Proteínas de Plantas/genética , Plasmodesmos/metabolismo , Plasmodesmos/ultraestrutura , ATPases Vacuolares Próton-Translocadoras/metabolismoRESUMO
KEY MESSAGE: Comparative transcriptome analysis of litchi ( Litchi chinensis Sonn.) buds at two developmental stages revealed multiple processes involving various phytohormones regulating floral initiation, and expression of numerous flowering-related genes. Floral initiation is a critical and complicated plant developmental process involving interactions of numerous endogenous and environmental factors, but little is known about the complex network regulating floral initiation in litchi (Litchi chinensis Sonn.). Illumina second-generation sequencing is an efficient method for obtaining massive transcriptional information resulting from phase changes in plant development. In this study, comparative transcriptomic analysis was performed with resting and emerging panicle stage buds, to gain further understanding of the molecular mechanisms involved in floral initiation in litchi. Abundance analysis identified 5,928 unigenes exhibiting at least twofold differences in expression between the two bud stages. Of these, 4,622 unigenes were up-regulated and 1,306 were down-regulated in panicle-emerging buds compared with resting buds. KEGG pathway enrichment analysis revealed that unigenes exhibiting differential expression were involved in the metabolism and signal transduction of various phytohormones. The expression levels of unigenes annotated as auxin, cytokinin, jasmonic acid, and salicylic acid biosynthesis were up-regulated, whereas those unigenes annotated as abscisic acid biosynthesis were down-regulated during floral initiation. In addition, 188 unigenes exhibiting sequence similarities to known flowering-related genes from other plants were differentially expressed during floral initiation. Thirteen genes were selected for confirmation of expression levels using quantitative-PCR. Our results provide abundant sequence resources for studying mechanisms underlying floral initiation in litchi and establish a platform for further studies of litchi and other evergreen fruit trees.
Assuntos
Flores/metabolismo , Litchi/genética , Litchi/metabolismo , Proteínas de Plantas/metabolismo , Análise de Sequência de RNA/métodos , Flores/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Proteínas de Plantas/genéticaRESUMO
SHORT VEGETATIVE PHASE (SVP), a member of the MADS-box transcription factor family, has been reported to regulate bud dormancy in deciduous perennial plants. Previously, three LcSVPs (LcSVP1, LcSVP2 and LcSVP3) were identified from litchi genome, and LcSVP2 was highly expressed in the terminal buds of litchi during growth cessation or dormancy stages and down-regulated during growth stages. In this study, the role of LcSVP2 in governing litchi bud dormancy was examined. LcSVP2 was highly expressed in the shoots, especially in the terminal buds at growth cessation stage, whereas low expression was showed in roots, female flowers and seeds. LcSVP2 was found to be located in the nucleus and have transcription inhibitory activity. Overexpression of LcSVP2 in Arabidopsis thaliana resulted in a later flowering phenotype compared to the wild-type control. Silencing LcSVP2 in growing litchi terminal buds delayed re-entry of dormancy, resulting in significantly lower dormancy rate. The treatment also significantly up-regulated litchi FLOWERING LOCUS T2 (LcFT2). Further study indicates that LcSVP2 interacts with an AP2-type transcription factor, SMALL ORGAN SIZE1 (LcSMOS1). Silencing LcSMOS1 promoted budbreak and delayed bud dormancy. Abscisic acid (200 mg/L), which enforced bud dormancy, induced a short-term increase in the expression of LcSVP2 and LcSMOS1. Our study reveals that LcSVP2 may play a crucial role, likely together with LcSMOS1, in dormancy onset of the terminal bud and may also serve as a flowering repressor in evergreen perennial litchi.
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Fruit abscission is a severe hindrance to commercial crop production, and a lack of carbohydrates causes fruit abscission to intensify in a variety of plant species. However, the precise mechanism by which carbohydrates affect fruit setting potential has yet to be determined. In the current study, we noticed negative correlation between hexose level and fruit setting by comparing different cultivars, bearing shoots of varying diameters, and girdling and defoliation treatments. The cumulative fruit-dropping rate was significantly reduced in response to exogenous glucose dipping. These results suggested that hexose, especially glucose, is the key player in lowering litchi fruit abscission. Moreover, five putative litchi hexokinase genes (LcHXKs) were isolated and the subcellular localization as well as activity of their expressed proteins in catalyzing hexose phosphorylation were investigated. LcHXK2 was only found in mitochondria and expressed catalytic protein, whereas the other four HXKs were found in both mitochondria and nuclei and had no activity in catalyzing hexose phosphorylation. LcHXK1 and LcHXK4 were found in the same cluster as previously reported hexose sensors AtHXK1 and MdHXK1. Furthermore, VIGS-mediated silencing assay confirms that LcHXK1 suppression increases fruit abscission. These findings revealed that LcHXK1 functions as hexose sensor, negatively regulating litchi fruit abscission.
Assuntos
Frutas , Litchi , Frutas/genética , Frutas/metabolismo , Hexoquinase/genética , Hexoquinase/metabolismo , Litchi/genética , Litchi/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , GlucoseRESUMO
Litchi is a highly perishable fruit. Ripe litchi fruit loses quality quickly as they hang on tree, giving a very short hanging life and thus harvest period. This study attempted to explore the roles of cytokinin in regulating fruit ripening and senescence of litchi and examine the possibility of applying cytokinin in "on-tree storage" of the fruit. Exogenous cytokinin, forchlorfenuron (CPPU), was applied at 20 mg L-1 7 weeks after full bloom on litchi (Litchi chinensis cv. Feizixiao) fruit clusters. Color parameters, chlorophylls, anthocyanins, fruit and fruit part weights, total soluble solutes (TSSs), soluble sugars, organic acids, non-anthocyanin flavonoids, ethanol, and also CPPU residue in fruit were traced. CPPU residue was higher but decreased faster in the pericarp than in the aril, where it maintained < 10 µg kg-1. CPPU had no significant effect on fruit weight but tended to increase pericarp weight. The treatment suppressed chlorophyll loss and anthocyanin accumulation in the pericarp, increased non-anthocyanin flavonoids in the aril, but had no significant effects on non-anthocyanin flavonoids in the pericarp and total sugar and organic acids in the aril. As the commercially ripe fruit hanged on tree, TSSs, total sugar, and sucrose decreased with ethanol and acetic acid accumulation in the aril. CPPU significantly suppressed the loss of sucrose and total sugar and the accumulation of ethanol and acetic acid in the aril and inhibited malondialdehyde accumulation in the pericarp of the overripe fruit. Soluble invertase, alcohol dehydrogenase, and pyruvate decarboxylase (PDC) activity and gene expression in the aril were downregulated by CPPU. The results suggest that cytokinin partially suppresses the ripening process in litchi and is effective to slow quality loss in the overripe fruit on tree.
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BACKGROUND: Bleeding from gastroesophageal varices (GOV) is a serious complication in patients with liver cirrhosis, carrying a very high mortality rate. For secondary prophylaxis against initial and recurrent bleeding, endoscopic therapy is a critical intervention. Endoscopic variceal clipping for secondary prophylaxis in adult GOV has not been reported. CASE SUMMARY: A 66-year-old man with cirrhosis was admitted to our hospital complaining of asthenia and hematochezia for 1 wk. His hemoglobin level and red blood cell counts were significantly decreased, and his fecal occult blood test was positive. An enhanced computed tomography of the abdomen showed GOV. The patient was diagnosed with hepatitis B cirrhosis-related GOV bleeding. A series of palliative treatments were administered, resulting in significant clinical improvement. Subsequently, an endoscopic examination revealed severe gastric fundal varices, prompting endoscopic variceal clipping. There were no further episodes of gastrointestinal bleeding. The GOV improved significantly on follow-up imaging and was confirmed as improved on endoscopy at the 5th postoperative month. CONCLUSION: Our results suggest that endoscopic clipping is an inexpensive, safe, easy, effective, and tolerable method for the secondary prophylaxis of bleeding from gastric type 2 GOV. However, additional research is indicated to confirm its long-term safety and efficacy.
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INTRODUCTION: Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies of gastrointestinal tract in the world, and the long-term prognosis for ESCC patients still remains dismal due to the lack of effective early diagnosis biomarkers. MATERIALS AND METHODS: Western blot and immunochemistry were used to determine the expression of PRR11 in 201 clinicopathologically characterized ESCC specimens. The effects of PRR11 on stem cell-like traits and tumorigenicity were examined by tumor sphere formation assay and SP assays in vitro and by a tumorigenesis model in vivo. The mechanism by which PRR11 mediated Wnt/ß-catenin signaling was explored using luciferase reporter, immuno-chemistry, and real time-PCR (RT-PCR) assays. RESULTS: We found that PRR11 was markedly upregulated, at the level of both transcription and translation, in ESCC cell lines as compared with normal esophageal epithelial cells (NECCs). Immunohistochemical analysis showed that 69.2% paraffin-embedded archival ESCC specimens exhibited high levels of PRR11 expression, and multivariate analysis revealed that PRR11 upregulation might be an independent prognostic indicator for the survival of patients with ESCC. Furthermore, overexpression of PRR11 dramatically enhanced, whereas inhibition of PRR11 reduced the capability of cancer stem cell (CSC)-like phenotypes and tumorigenicity of ESCC cells both in vitro and in vivo. Mechanically, we demonstrated PRR11-enhanced tumorigenicity of ESCC cells via activating Wnt/ß-catenin signaling, and PRR11 expression is found to be significantly correlated with ß-catenin nuclear location in ESCC. CONCLUSION: Our findings suggest that the PRR11 might represent a novel and valuable prognostic marker for ESCC progression and play a role during the development and progression of this malignancy.
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BACKGROUND: Glioma is the most lethal primary brain tumor, the survival rate still isn't improved in the past decades. It's essential to study the regulatory mechanism of glioma progression, hoping to find new therapy targets or methods. The family of tripartite motif (TRIM) containing proteins are E3 ubiquitination ligases, which play critical role in various tumor progression. METHODS: Cell proliferation and invasion were analyzed by colony formation assay, soft agar growth assay, BrdU incorporation assay and transwell invasion assay. Luciferase reporter analysis was used to analyze NF-κB pathway activity. RESULTS: We found TRIM31 was upregulated in glioma cells and tissues, its overexpression significantly promoted glioma cell proliferation and invasion, while its knockdown significantly inhibited glioma cell proliferation and invasion. Mechanism analysis found TRIM31 promoted NF-κB pathway activity and increased its targets expression. NF-κB inhibition reversed the phenotype caused by TRIM31, confirming TRIM31 promoted glioma progression through activating NF-κB pathway. Using clinical specimens found TRIM31 expression was positively correlative with NF-κB activity. CONCLUSION: This study found TRIM31 promoted glioma proliferation and invasion through activating NF-κB activity.
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This research was aimed to explore correlation of gene polymorphisms of CD36 and ApoE with susceptibility of Alzheimer disease (AD).This study was a case-control study. Two hundred eleven AD hospitalized patients were selected as the AD group and 241 subjects were selected as the control group. PCR-RFLP was used to detect three loci (rs7755, rs3211956, and rs10499859) of CD36 gene and ApoE genotype. Chi-square test and univariate nonconditional logistic regression analysis were used to calculate the odds ratio (OR) and 95% confidence interval (95% CI). The haplotypes were constructed using SHEsis online software and the correlation between haplotypes and AD was analyzed. Meanwhile, differences of 3 alleles of ApoE and 6 genotypes (E2/E2, E2/E3, E2/E4, E3/E3, E3/E4, E4/E4) were compared between AD and control groups.The frequencies of rs7755 genotype (χâ=â10.780, Pâ=â.005) and allele (χâ=â10.549, Pâ=â.001) were statistically different between 2 groups. The genotype frequency of rs3211956 was statistically different between AD and control groups (χâ=â10.119, Pâ=â.006). For the rs7755 locus, GG genotype (OR: 2.013, 95% CI: 1.098-3.699) was an independent risk factor for AD compared with AA genotype. In the dominant model, the risk to develop AD in AG/GG genotype was 1.686 times higher than AA genotype. For the rs3211956 locus, compared with TT genotype, GT genotype (OR: 0.536, 95% CI: 0.340-0.846) was a protective factor for AD after adjusting various physiological and biochemical factors. In the dominant model, the risk of GT/GG genotype to develop AD was reduced by 41.6%. For ApoE gene, the distribution differences of E2/E3 (χâ=â9.216, Pâ=â.002), E3/E4 (χâ=â7.728, Pâ=â.005), and E4/E4 had statistical significance between the 2 groups. The frequencies of allele E2 (χâ=â9.359, Pâ=â.002) and E4 (χâ=â13.995, Pâ<â.001) were statistically significant between AD and control groups.The rs7755 and rs3211956 loci polymorphisms of CD36 gene and genotype E2/E3, E3/E4, E4/E4 of ApoE gene, and E2 and E4 alleles were statistically related with AD.
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Doença de Alzheimer/genética , Apolipoproteínas E/genética , Antígenos CD36/genética , Predisposição Genética para Doença/genética , Polimorfismo de Nucleotídeo Único , Idoso , Alelos , Estudos de Casos e Controles , Feminino , Frequência do Gene , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de RiscoRESUMO
Calcium (Ca) deficiency in fruit causes various physiological disorders leading to quality loss. However, disorders related to Ca deficiency are not simply caused by a shortage of calcium supply. Ca distribution is also an important relation. This study examined Ca distribution pattern in fruit and pedicel in litchi (Litchi chinensis Sonn.) and the influence of Ca channel inhibitor La3+ on fruit Ca uptake and distribution. In situ distribution of Ca in the phloem and xylem tissues of the pedicel was visualized by Ca mapping with X-ray microanalyzer. Ca2+ analogy Sr2+ was used to trace Ca2+ transport pathway to fruit as well as distribution pattern. The results showed Ca was more distributed in the pericarp, especially the distal part. Ca level in the bark/phloem was always significantly higher than in the xylem and increased with stem age, suggesting constant influx of Ca into the phloem from the xylem. La3+ increased the ratio of Ca in the xylem to that in the bark in the pedicel and significantly reduced Ca accumulation by 55.6% in fruit, suggesting influx of Ca into the symplast was involved in fruit Ca uptake. Sr2+ introduced from fruit stalk was found to be transported to fruit through the phloem as Sr was largely distributed in the phloem, and fruit stalk girdling significantly reduced Sr accumulation in the pericarp. Ca mapping across the pedicel revealed Ca-rich sites in the parenchyma cells in the phloem and along the cambium, where abundant Ca oxalate crystals were found. The results suggested extensive influx of Ca from xylem/apoplast pathway into the phloem/symplast pathway in the pedicel, which enables phloem/symplast pathway to contribute a considerable part to Ca uptake in litchi fruit.
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ß-Amyloid protein (Aß) is thought to cause neuronal loss in Alzheimer's disease (AD). Aß treatment promotes the re-activation of a mitotic cycle and induces rapid apoptotic death of neurons. However, the signaling pathways mediating cell-cycle activation during neuron apoptosis have not been determined. We find that Wnt5a acts as a mediator of cortical neuron survival, and Aß42 promotes cortical neuron apoptosis by downregulating the expression of Wnt5a. Cell-cycle activation is mediated by the reduced inhibitory effect of Wnt5a in Aß42 treated cortical neurons. Furthermore, Wnt5a signals through the non-canonical Wnt/Ca2+ pathway to suppress cyclin D1 expression and negatively regulate neuronal cell-cycle activation in a cell-autonomous manner. Together, aberrant downregulation of Wnt5a signaling is a crucial step during Aß42 induced cortical neuron apoptosis and might contribute to AD-related neurodegeneration.
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Among the 5 tested litchi (Litchi chinensis Sonn.) cultivars ("Huaizhi", "Guiwei", "Nuomici", "Hongmili" and "Shuijingqiu", "Nuomici" became deteriorated much faster than other cultivars while "Guiwei" fruit was the slowest in the rotting process (Fig. 1A). Fruit deterioration was accompanied by fruit desiccation (Fig. 2B), but the speed of water loss was not significantly correlated to fruit deterioration rate, indicating that it was not the key factor causing the difference in postharvest performance among cultivars. Fruit deterioration rate was significantly positively correlated to membrane leakage (Fig. 2A), suggesting the capacity to maintain membrane integrity is closely related to the shelflife of litchi. Skin browning potential, uronic acid concentration, degree of methylation of pectin and soluble Ca content in pericarp as well as total Ca content in the pulp were not significantly correlated with fruit deterioration. Content of structural Ca (water-insoluble but acetic acid-soluble calcium, membrane or wall-bound Ca), the major form of Ca in the pericarp, was negatively correlated to fruit deterioration rate (Fig. 2E). The results proved that differences in fruit desiccation rate, browning potential, Ca other than structural form were not the major cause leading to difference in postharvest performance among different cultivars. "Guiwei" being more tolerant to desiccation than other cultivars is likely associated its higher structural Ca concentration in the pericarp.
Assuntos
Frutas/fisiologia , Litchi/fisiologia , Cálcio/metabolismo , Frutas/metabolismo , Litchi/classificação , Litchi/metabolismo , Especificidade da Espécie , Fatores de Tempo , Água/metabolismoRESUMO
OBJECTIVE: To analyze the biomechanics of impact injury in the condition of the simulate impact on mandible. METHODS: A finite element model of human mandible was developed from the CT scan images by the technologies of three-dimensional reconstruction, image processing and meshing. The mandible model was connected to a modified head model of HYBRID III dummy with joint according to the anatomic structure and mechanical characteristics of the temporomandibular joint. RESULTS: A finite element model of human head with true anatomic structure mandible has been developed. This model has been validated with the cadaver test results. The higher stress was showed in the condyle rejoins and coracoid in the model when mandible was in impact simulation. CONCLUSIONS: This model can be used to research the mechanism of craniofacial blunt-impact injury and assess the injury severity. The model of HYBRID III dummy with the human mandible was helpful for the boundary design of mandibular model in the impact simulations.