RESUMO
Much evidence exists suggesting the presence of genetic functional diversification in plants, though literature associated with the role of functional diversification in the evolution of the plant secondary cell wall (SCW) has sparsely been compiled and reviewed in a recent context. This review aims to elucidate, through the examination of gene phylogenies associated with its biosynthesis and maintenance, the role of functional diversification in shaping the critical, dynamic, and characteristic organelle, the secondary cell wall. It will be asserted that gene families resulting from gene duplication and subsequent functional divergence are present and are heavily involved in SCW biosynthesis and maintenance. Furthermore, diversification will be presented as a significant driver behind the evolution of the many functional characteristics of the SCW. The structure and function of the plant cell wall and its constituents will first be explored, followed by a discussion on the phenomenon of gene duplication and the resulting genetic functional divergence that can emerge. Finally, the major constituents of the SCW and their individual relationships with duplication and divergence will be reviewed to the extent of current knowledge on the subject.
Assuntos
Parede Celular , Plantas , Plantas/genética , Parede Celular/genética , Duplicação Gênica , Regulação da Expressão Gênica de PlantasRESUMO
Herpes simplex virus 1 (HSV-1) establishes life-long latent infection within sensory neurons, during which viral lytic gene expression is silenced. The only highly expressed viral gene product during latent infection is the latency-associated transcript (LAT), a non-protein coding RNA that has been strongly implicated in the epigenetic regulation of HSV-1 gene expression. We have investigated LAT-mediated control of latent gene expression using chromatin immunoprecipitation analyses and LAT-negative viruses engineered to express firefly luciferase or ß-galactosidase from a heterologous lytic promoter. Whilst we were unable to determine a significant effect of LAT expression upon heterochromatin enrichment on latent HSV-1 genomes, we show that reporter gene expression from latent HSV-1 genomes occurs at a greater frequency in the absence of LAT. Furthermore, using luciferase reporter viruses we have observed that HSV-1 gene expression decreases during long-term latent infection, with a most marked effect during LAT-negative virus infection. Finally, using a fluorescent mouse model of infection to isolate and culture single latently infected neurons, we also show that reactivation occurs at a greater frequency from cultures harbouring LAT-negative HSV-1. Together, our data suggest that the HSV-1 LAT RNA represses HSV-1 gene expression in small populations of neurons within the mouse TG, a phenomenon that directly impacts upon the frequency of reactivation and the maintenance of the transcriptionally active latent reservoir.
Assuntos
Regulação Viral da Expressão Gênica , Herpesvirus Humano 1/genética , Neurônios/metabolismo , Transcrição Gênica , Proteínas Virais/genética , Latência Viral/genética , Fenômenos Fisiológicos Virais/genética , Animais , Células Cultivadas , Epigênese Genética/genética , Expressão Gênica/genética , RNA Viral/genética , RNA Viral/metabolismoRESUMO
Sugar cane is a major source of food and fuel worldwide. Biotechnology has the potential to improve economically-important traits in sugar cane as well as diversify sugar cane beyond traditional applications such as sucrose production. High levels of transgene expression are key to the success of improving crops through biotechnology. Here we describe new molecular tools that both expand and improve gene expression capabilities in sugar cane. We have identified promoters that can be used to drive high levels of gene expression in the leaf and stem of transgenic sugar cane. One of these promoters, derived from the Cestrum yellow leaf curling virus, drives levels of constitutive transgene expression that are significantly higher than those achieved by the historical benchmark maize polyubiquitin-1 (Zm-Ubi1) promoter. A second promoter, the maize phosphonenolpyruvate carboxylate promoter, was found to be a strong, leaf-preferred promoter that enables levels of expression comparable to Zm-Ubi1 in this organ. Transgene expression was increased approximately 50-fold by gene modification, which included optimising the codon usage of the coding sequence to better suit sugar cane. We also describe a novel dual transcriptional enhancer that increased gene expression from different promoters, boosting expression from Zm-Ubi1 over eightfold. These molecular tools will be extremely valuable for the improvement of sugar cane through biotechnology.
Assuntos
Biotecnologia/métodos , Regulação da Expressão Gênica de Plantas , Folhas de Planta/genética , Caules de Planta/genética , Saccharum/genética , Agricultura/métodos , Histocitoquímica , Folhas de Planta/metabolismo , Caules de Planta/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Saccharum/metabolismo , beta-Glucosidase/genética , beta-Glucosidase/metabolismoRESUMO
Chemically inducible gene switches can provide precise control over gene expression, enabling more specific analyses of gene function and expanding the plant biotechnology toolkit beyond traditional constitutive expression systems. The alc gene expression system is one of the most promising chemically inducible gene switches in plants because of its potential in both fundamental research and commercial biotechnology applications. However, there are no published reports demonstrating that this versatile gene switch is functional in transgenic monocotyledonous plants, which include some of the most important agricultural crops. We found that the original alc gene switch was ineffective in the monocotyledonous plant sugar cane, and describe a modified alc system that is functional in this globally significant crop. A promoter consisting of tandem copies of the ethanol receptor inverted repeat binding site, in combination with a minimal promoter sequence, was sufficient to give enhanced sensitivity and significantly higher levels of ethanol inducible gene expression. A longer CaMV 35S minimal promoter than was used in the original alc gene switch also substantially improved ethanol inducibility. Treating the roots with ethanol effectively induced the modified alc system in sugar cane leaves and stem, while an aerial spray was relatively ineffective. The extension of this chemically inducible gene expression system to sugar cane opens the door to new opportunities for basic research and crop biotechnology.
Assuntos
Etanol/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Saccharum/genética , Álcool Desidrogenase/genética , Aspergillus nidulans/genética , Caulimovirus/genética , Produtos Agrícolas/genética , Proteínas Fúngicas/genética , Glucuronidase/genética , Glucuronidase/metabolismo , Histocitoquímica , Dados de Sequência Molecular , Folhas de Planta/genética , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Saccharum/metabolismoRESUMO
Trace organic contaminant (TrOC) studies in Australia have, to date, focused on wastewater effluents, leaving a knowledge gap of their occurrence and risk in freshwater environments. This study measured 42 TrOCs including industrial compounds, pesticides, and pharmaceuticals and personal care products by liquid chromatography tandem mass spectrometry at 73 river sites across Australia quarterly for 1 yr. Trace organic contaminants were found in 92% of samples, with a median of three compounds detected per sample (maximum 18). The five most commonly detected TrOCs were the pharmaceuticals salicylic acid (82%, maximum = 1530 ng/L), paracetamol (also known as acetaminophen; 45%, maximum = 7150 ng/L), and carbamazepine (27%, maximum = 682 ng/L), caffeine (65%, maximum = 3770 ng/L), and the flame retardant (2-chloroethyl) phosphate (44%, maximum = 184 ng/L). Pesticides were detected in 28% of the samples. To determine the risk posed by the detected TrOCs to the aquatic environment, hazard quotients were calculated by dividing the maximum concentration detected for each compound by the predicted no-effect concentrations. Three of the 42 compounds monitored (the pharmaceuticals carbamazepine and sulfamethoxazole and the herbicide simazine) had a hazard quotient >1, suggesting that they may be causing adverse effects at the most polluted sites. A further 10 compounds had hazard quotients >0.1, indicating a potential risk; these included four pharmaceuticals, three personal care products, and three pesticides. Most compounds had hazard quotients significantly <0.1. The number of TrOCs measured in this study was limited and further investigations are required to fully assess the risk posed by complex mixtures of TrOCs on exposed biota.
RESUMO
This study focuses on the performance of a submerged membrane photocatalytic reactor for the removal of 17beta-oestradiol (E2) in the presence of humic acid (HA). In addition to the impact of operating parameters, such as membrane pore size, ultraviolet (UV) intensity and hydraulic retention time (HRT), the influence of long-term operation was also assessed by advanced characterization of the fouling layer formed on the membrane. The tighter (0.04 microm) hollow fibre polyvinylydene fluoride (PVDF) membrane was found to exhibit not only higher HA removal than the (0.2 microm) module (85% and 75%, respectively), but also greater transmembrane pressure (TMP) values and higher irreversible fouling. Long-term operation conditions have been simulated by conducting an ageing catalyst process and demonstrated a decrease in performance obtained with time. The artificially aged TiO2 resulted in higher TMP values and lower HA removals (about 10-20% decrease) compared with the non-aged catalyst. For E2 removal in the presence of HA, the passive adsorption of the oestrogen onto the organic matter was found to be significant (40% of the E2 adsorbed after I h), demonstrating the importance of the nature of the water matrix for this type of treatment process. An increase in the UV light intensity was observed to favour the E2 elimination, leading to more than 90% removal when using 64 W combined with PVDF membrane and an HRT of 3 h.
Assuntos
Disruptores Endócrinos/isolamento & purificação , Estradiol/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Reatores Biológicos , Substâncias Húmicas , Membranas Artificiais , Fotólise , Titânio , Raios UltravioletaRESUMO
The plant cell wall serves as a critical interface between the plant and its environment, offering protection against various stresses and contributing to biomass production. Hemicellulose is one of the major components of the cell wall, and understanding the transcriptional regulation of its production is essential to fully understanding cell wall formation. This study explores the regulatory mechanisms underlying one of the genes involved in hemicellulose biosynthesis, PtrPARVUS2. Six transcription factors (TFs) were identified from a xylem-biased library to negatively regulate PtrPARVUS2 expression. These TFs, belonging to diverse TF families, were confirmed to bind to specific cis-elements in the PtrPARVUS2 promoter region, as validated by Yeast One-Hybrid (Y1H) assays, transient expression analysis, and Chromatin Immunoprecipitation sequencing (ChIP-seq) assays. Furthermore, motif analysis identified putative cis-regulatory elements bound by these TFs, shedding light on the transcriptional regulation of SCW biosynthesis genes. Notably, several TFs targeted genes encoding uridine diphosphate glycosyltransferases (UGTs), crucial enzymes involved in hemicellulose glycosylation. Phylogenetic analysis of UGTs regulated by these TFs highlighted their diverse roles in modulating hemicellulose synthesis. Overall, this study identifies a set of TFs that regulate PARVUS2 in poplar, providing insights into the intricate coordination of TFs and PtrPARVUS2 in SCW formation. Understanding these regulatory mechanisms enhances our ability to engineer plant biomass for tailored applications, including biofuel production and bioproduct development.
Assuntos
Regulação da Expressão Gênica de Plantas , Polissacarídeos , Populus , Regiões Promotoras Genéticas , Fatores de Transcrição , Populus/genética , Populus/metabolismo , Polissacarídeos/metabolismo , Polissacarídeos/biossíntese , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Filogenia , Parede Celular/metabolismo , Parede Celular/genéticaRESUMO
The Department of Veterans Affairs (VA) utilizes a pharmacogenomic (PGx) program that analyzes specific "pharmacogenes." This study evaluates the effect that pharmacogenes may have on prevalence of polypharmacy. This retrospective cohort study included patients with VA prescriptions who underwent PGx testing. We quantified prescriptions active or recently expired at the time of PGx testing. We constructed two co-primary polypharmacy (≥10 medications) end points: (i) based on all medications and (ii) requiring that at least one medication was affected by a pharmacogene of interest. Pharmacogenes and actionable phenotypes of interest included poor and ultrarapid metabolizers for CYP2D6, CYP2C9, and CYP2C19 and intermediate and normal metabolizers for CYP3A5. Patients were classified as having 0, 1, and 2+ total phenotypes across all genes. Of the 15,144 patients screened, 13,116 met eligibility criteria. Across phenotype cohorts, there was no significant association with polypharmacy using all medications, number of total medications, or number of medications affected by phenotypes. However, there was a significant difference in patients with polypharmacy prescribed ≥1 medication impacted by PGx across phenotype groups: 2,514/4,949 (51%), 1,349/2,595 (52%), 204/350 (58%) (P = 0.03, OR 1.31, 95% CI 1.02-1.67). The median number of medications affected by PGx phenotypes with ≥1 PGx-impacted medication across phenotype groups was a median of 0 (IQR 0, 0), 0 (IQR 0, 0), and 1 (IQR 0, 1) (P < 0.001). In patients prescribed ≥1 medication impacted by PGx, those with more actionable pharmacogenomic phenotypes were more likely to meet polypharmacy criteria.
Assuntos
Citocromo P-450 CYP2C19 , Citocromo P-450 CYP2C9 , Citocromo P-450 CYP2D6 , Citocromo P-450 CYP3A , Fenótipo , Polimedicação , Veteranos , Humanos , Masculino , Estudos Retrospectivos , Feminino , Idoso , Citocromo P-450 CYP2C19/genética , Citocromo P-450 CYP2D6/genética , Pessoa de Meia-Idade , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP2C9/genética , Estados Unidos , Farmacogenética , Testes Farmacogenômicos , Estudos de Coortes , Variantes Farmacogenômicos , United States Department of Veterans AffairsRESUMO
Angelman Syndrome (AS) is a rare genetic disorder that impacts 1:20,000 people. Challenging behaviour, such as severe injurious behaviour, aggression and frequent unprovoked episodes of laughter are a significant problem among adults with AS that adversely impacts an individual's quality of life. This study, for the first time, aims understand the characteristic of challenging behaviour, its frequency, and the factors associated with it in adults with AS. Data from participants with AS (N = 37; aged 18-46 years) registered with the Global Angelman Registry, were divided into challenging behaviour and non-challenging behaviour groups based on the presence or absence of 50% of the behaviours recorded in the registry. Descriptive statistics, chi-squared and t-test analysis were conducted to assess the impact of variables on challenging behaviour. Multiple regressions were conducted to investigate the predictors of challenging behaviour. 56% of the sample presented with challenging behaviour. Disorders of arousal, self-injury, behaviour dysregulation, repetitive behaviour, and the lack of physical therapy accounted for 59% of the variance of challenging behaviour in this population. It was found that challenging behaviour was very common in this population. A significant association was found between challenging behaviour and both sleep arousal and the lack of physical therapy. Sleep arousal and the lack of physical therapy were the key factors associated with challenging behaviour in this study. Targeted interventions are needed to decrease challenging behaviour and future research should focus on sleep interventions and increased opportunities for physical therapy.
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Large-scale biofuel production from lignocellulosic feedstock is limited by the financial and environmental costs associated with growing and processing lignocellulosic material and the resilience of these plants to environmental stress. Symbiotic associations with arbuscular (AM) and ectomycorrhizal (EM) fungi represent a potential strategy for expanding feedstock production while reducing nutrient inputs. Comparing AM and EM effects on wood production and chemical composition is a necessary step in developing biofuel feedstocks. Here, we assessed the productivity, biomass allocation and secondary cell wall (SCW) composition of greenhouse-grown Populus tremuloidesMichx. inoculated with either AM or EM fungi. Given the long-term goal of reducing nutrient inputs for biofuel production, we further tested the effects of nutrient availability and nitrogen:phosphorus stoichiometry on mycorrhizal responses. Associations with both AM and EM fungi increased plant biomass by 14-74% depending on the nutrient conditions but had minimal effects on SCW composition. Mycorrhizal plants, especially those inoculated with EM fungi, also allocated a greater portion of their biomass to roots, which could be beneficial in the field where plants are likely to experience both water and nutrient stress. Leaf nutrient content was weakly but positively correlated with wood production in mycorrhizal plants. Surprisingly, phosphorus played a larger role in EM plants compared with AM plants. Relative nitrogen and phosphorus availability were correlated with shifts in SCW composition. For AM associations, the benefit of increased wood biomass may be partially offset by increased lignin content, a trait that affects downstream processing of lignocellulosic tissue for biofuels. By comparing AM and EM effects on the productivity and chemical composition of lignocellulosic tissue, this work links broad functional diversity in mycorrhizal associations to key biofuel traits and highlights the importance of considering both biotic and abiotic factors when developing strategies for sustainable biofuel production.
Assuntos
Micorrizas , Populus , Micorrizas/fisiologia , Biomassa , Populus/microbiologia , Biocombustíveis , Raízes de Plantas/microbiologia , Plantas , Nutrientes , Fósforo , Nitrogênio , SoloRESUMO
Hybrid poplar (Populus tremula X P. alba) genetically engineered to express the pine cytosolic glutamine synthetase gene (GS1a) has been previously shown to display desirable field performance characteristics, including enhancements in growth and nitrogen use efficiency. Analysis of wood samples from a 3-year-old field trial of three independently transformed GS1a transgenic hybrid poplar lines revealed that, when compared with wild-type controls, ectopic expression of GS1a resulted in alterations in wood properties and wood chemistry. Included were significant enhancements in wood fibre length, wood density, microfibre angle, per cent syringyl lignin and elevated concentrations of wood sugars, specifically glucose, galactose, mannose and xylose. Total extractive content and acid-insoluble lignin were significantly reduced in wood of GS1a transgenics when compared with wild-type trees. Together, these cell wall characteristics resulted in improved wood pulping attributes, including improved lignin solubilization with no concurrent decrease in yield. Trees with increased GS1a expression have improved characteristics for pulp and paper production and hold potential as a feedstock for biofuels production.
Assuntos
Glutamato-Amônia Ligase/metabolismo , Populus/enzimologia , Populus/crescimento & desenvolvimento , Madeira/química , Parede Celular/metabolismo , Cruzamentos Genéticos , Glutamato-Amônia Ligase/genética , Hibridização Genética , Lignina/metabolismo , Plantas Geneticamente Modificadas , Populus/genéticaRESUMO
Overexpression of the Gossypium hirsutum sucrose synthase (SuSy) gene under the control of 2 promoters was examined in hybrid poplar (Populus alba x grandidentata). Analysis of RNA transcript abundance, enzyme activity, cell wall composition, and soluble carbohydrates revealed significant changes in the transgenic lines. All lines showed significantly increased SuSy enzyme activity in developing xylem. This activity manifested in altered secondary cell wall cellulose content per dry weight in all lines, with increases of 2% to 6% over control levels, without influencing plant growth. The elevated concentration of cellulose was associated with an increase in cell wall crystallinity but did not alter secondary wall microfibril angle. This finding suggests that the observed increase in crystallinity is a function of altered carbon partitioning to cellulose biosynthesis rather than the result of tension wood formation. Furthermore, the augmented deposition of cellulose in the transgenic lines resulted in thicker xylem secondary cell wall and consequently improved wood density. These findings clearly implicate SuSy as a key regulator of sink strength in poplar trees and demonstrate the tight association of SuSy with cellulose synthesis and secondary wall formation.
Assuntos
Carbono/metabolismo , Parede Celular/ultraestrutura , Celulose/biossíntese , Glucosiltransferases/fisiologia , Populus/metabolismo , Biomassa , Parede Celular/química , Glucosiltransferases/genética , Lignina/análise , Populus/ultraestrutura , Sacarose/metabolismo , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismoRESUMO
Herpes simplex virus (HSV) type-1 establishes lifelong latency in sensory neurones and it is widely assumed that latency is the consequence of a failure to initiate virus immediate-early (IE) gene expression. However, using a Cre reporter mouse system in conjunction with Cre-expressing HSV-1 recombinants we have previously shown that activation of the IE ICP0 promoter can precede latency establishment in at least 30% of latently infected cells. During productive infection of non-neuronal cells, IE promoter activation is largely dependent on the transactivator VP16 a late structural component of the virion. Of significance, VP16 has recently been shown to exhibit altered regulation in neurones; where its de novo synthesis is necessary for IE gene expression during both lytic infection and reactivation from latency. In the current study, we utilized the Cre reporter mouse model system to characterize the full extent of viral promoter activity compatible with cell survival and latency establishment. In contrast to the high frequency activation of representative IE promoters prior to latency establishment, cell marking using a virus recombinant expressing Cre under VP16 promoter control was very inefficient. Furthermore, infection of neuronal cultures with VP16 mutants reveals a strong VP16 requirement for IE promoter activity in non-neuronal cells, but not sensory neurones. We conclude that only IE promoter activation can efficiently precede latency establishment and that this activation is likely to occur through a VP16-independent mechanism.
Assuntos
Regulação Viral da Expressão Gênica , Genes Precoces , Proteína Vmw65 do Vírus do Herpes Simples/metabolismo , Herpesvirus Humano 1/fisiologia , Regiões Promotoras Genéticas , Células Receptoras Sensoriais/virologia , Latência Viral , Animais , Feminino , Herpesvirus Humano 1/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BLRESUMO
A major strategic goal in making ethanol from lignocellulosic biomass a cost-competitive liquid transport fuel is to reduce the cost of production of cellulolytic enzymes that hydrolyse lignocellulosic substrates to fermentable sugars. Current production systems for these enzymes, namely microbes, are not economic. One way to substantially reduce production costs is to express cellulolytic enzymes in plants at levels that are high enough to hydrolyse lignocellulosic biomass. Sugar cane fibre (bagasse) is the most promising lignocellulosic feedstock for conversion to ethanol in the tropics and subtropics. Cellulolytic enzyme production in sugar cane will have a substantial impact on the economics of lignocellulosic ethanol production from bagasse. We therefore generated transgenic sugar cane accumulating three cellulolytic enzymes, fungal cellobiohydrolase I (CBH I), CBH II and bacterial endoglucanase (EG), in leaves using the maize PepC promoter as an alternative to maize Ubi1 for controlling transgene expression. Different subcellular targeting signals were shown to have a substantial impact on the accumulation of these enzymes; the CBHs and EG accumulated to higher levels when fused to a vacuolar-sorting determinant than to an endoplasmic reticulum-retention signal, while EG was produced in the largest amounts when fused to a chloroplast-targeting signal. These results are the first demonstration of the expression and accumulation of recombinant CBH I, CBH II and EG in sugar cane and represent a significant first step towards the optimization of cellulolytic enzyme expression in sugar cane for the economic production of lignocellulosic ethanol.
Assuntos
Celulase/metabolismo , Celulose 1,4-beta-Celobiosidase/metabolismo , Folhas de Planta/enzimologia , Proteínas Recombinantes de Fusão/metabolismo , Saccharum/enzimologia , Sequência de Aminoácidos , Aspergillus/enzimologia , Aspergillus/genética , Bactérias/enzimologia , Bactérias/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Western Blotting , Celulase/genética , Celulose 1,4-beta-Celobiosidase/genética , Cloroplastos/metabolismo , Clonagem Molecular , Retículo Endoplasmático/metabolismo , Ativação Enzimática , Ensaios Enzimáticos , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Vetores Genéticos , Dados de Sequência Molecular , Folhas de Planta/genética , Plantas Geneticamente Modificadas/enzimologia , Plantas Geneticamente Modificadas/genética , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão/genética , Saccharum/genética , Transgenes , Zea mays/genéticaRESUMO
p-Coumaroyl-CoA 3'-hydroxylase (C3'H) is a cytochrome P450-dependent monooxygenase that catalyzes the 3'-hydroxylation of p-coumaroyl shikimate and p-coumaroyl quinate. We used RNA interference to generate transgenic hybrid poplar suppressed in C3'H expression and analyzed them with respect to transcript abundance, cell wall structure and chemical composition, and soluble metabolite levels. RT-PCR expression profiles confirmed the down-regulation of C3'H in a number of lines, which generally correlated very well with reduced total cell wall lignin content. The most strongly repressed line was chosen for further analysis and compared with the wild-type trees. In-depth characterization revealed that along with the significant decrease in total lignin content, a significant shift in lignin monomer composition was observed, favoring the generation of p-hydroxyphenyl units at the expense of guaiacyl units while the proportion of syringyl moieties remained constant. Suppression of C3'H also resulted in the accumulation of substantial pools of 1-O-p-coumaroyl-beta-d-glucoside and other phenylpropanoid glycosides, and p-coumaroyl shikimate, providing further insight into the role of C3'H in the lignin biosynthetic pathway. The data presented indicate that when down-regulated, C3'H becomes a rate-limiting step in lignin biosynthesis and further support the involvement of hydroxycinnamic acid shikimate esters in the lignin biosynthetic pathway.
Assuntos
Regulação Enzimológica da Expressão Gênica/genética , Lignina/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Interferência de RNA , Lignina/química , Estrutura Molecular , Populus/enzimologia , Populus/genética , Solubilidade , Transcrição Gênica/genéticaRESUMO
A potential method by which society's reliance on fossil fuels can be lessened is via the large-scale utilization of biofuels derived from the secondary cell walls of woody plants; however, there remain a number of technical challenges to the large-scale production of biofuels. Many of these challenges emerge from the underlying complexity of the secondary cell wall. The challenges associated with lignin have been well explored elsewhere, but the dicot cell wall components of hemicellulose and pectin also present a number of difficulties. Here, we provide an overview of the research wherein pectin and xylan biosynthesis has been altered, along with investigations on the function of irregular xylem 8 (IRX8) and glycosyltransferase 8D (GT8D), genes putatively involved in xylan and pectin synthesis. Additionally, we provide an analysis of the evidence in support of two hypotheses regarding GT8D and conclude that while there is evidence to lend credence to these hypotheses, there are still questions that require further research and examination.
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A major challenge for sustainable food, fuel, and fiber production is simultaneous genetic improvement of yield, biomass quality, and resilience to episodic environmental stress and climate change. For Populus and other forest trees, quality traits involve alterations in the secondary cell wall (SCW) of wood for traditional uses, as well as for a growing diversity of biofuels and bioproducts. Alterations in wood properties that are desirable for specific end uses can have negative effects on growth and stress tolerance. Understanding of the diverse roles of SCW genes is necessary for the genetic improvement of fast-growing, short-rotation trees that face perennial challenges in their growth and development. Here, we review recent progress into the synergies and antagonisms of SCW development and abiotic stress responses, particularly, the roles of transcription factors, SCW biogenesis genes, and paralog evolution.
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Nicotiana tabacum (tobacco) was transformed with three genes involved in sucrose metabolism, UDP-glucose pyrophosphorylase (UGPase, EC 2.7.7.9), sucrose synthase (SuSy, EC 2.4.1.13) and sucrose phosphate synthase (SPS, EC 2.4.1.14). Plants harbouring the single transgenes were subsequently crossed to produce double and triple transgenic lines, including: 2 x 35S::UGPase x SPS, 4CL::UGPase x SPS, 2 x 35S::SuSy x SPS, 4CL::SuSy x SPS, 2 x 35S::UGPase x SuSy x SPS, and 4CL::UGPase x SuSy x SPS. The ultimate aim of the study was to examine whether it is possible to alter cellulose production through the manipulation of sucrose metabolism genes. While altering sucrose metabolism using UGPase, SuSy and SPS does not have an end effect on cellulose production, their simultaneous overexpression resulted in enhanced primary growth as seen in an increase in height growth, in some cases over 50%. Furthermore, the pyramiding strategy of simultaneously altering the expression of multiple genes in combination resulted in increased time to reproductive bud formation as well as altered flower morphology and foliar stipule formation in 4CL lines. Upregulation of these sucrose metabolism genes appears to directly impact primary growth and therefore biomass production in tobacco.
Assuntos
Biomassa , Flores/crescimento & desenvolvimento , Nicotiana , Plantas Geneticamente Modificadas , Sacarose/metabolismo , Regulação para Cima , Biotecnologia/métodos , Regulação da Expressão Gênica de Plantas , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Plantas Geneticamente Modificadas/enzimologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo , Nicotiana/enzimologia , Nicotiana/genética , Nicotiana/crescimento & desenvolvimento , Nicotiana/metabolismo , Transgenes/genética , Transgenes/fisiologia , UTP-Glucose-1-Fosfato Uridililtransferase/genética , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismoRESUMO
A membrane bioreactor (MBR) was assessed for the removal of estrogens, androgens, and a selection of pharmaceuticals and personal care products. The biomass and aqueous components of the MBR were investigated to determine whether removal was by biodegradation or by adsorption to the biomass. Removal was monitored using chemical analysis by gas chromatography/mass spectrometry (GC-MS) as well as biological analysis using estrogenic and androgenic yeast assays. Results showed that the MBR was effective in removing the compounds of concern from raw influent with removal rates between 78 and 99%. Removal efficiencies were comparable or better than those reported for conventional activated sludge systems, which was attributed to the relatively high sludge retention time of the MBR. The biomass component showed significant concentrations of salicylic acid, triclosan, and 4-tert-octylphenol. Estrogenic and androgenic activity was also measured in the biomass. Estrone was identified as the main compound responsible for the estrogenic activity. It was concluded that the main removal pathway was biodegradation, but sorption to biomass may also be important, particularly for triclosan and 4-tert-octylphenol.
Assuntos
Reatores Biológicos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos/isolamento & purificação , Esgotos/análise , Androgênios/isolamento & purificação , Biodegradação Ambiental , Biomassa , Estrogênios/isolamento & purificação , Eliminação de Resíduos Líquidos , Purificação da Água , Leveduras/efeitos dos fármacosRESUMO
Native Americans (NAs) have a higher prevalence of chronic pain than any other U.S. racial/ethnic group; however, little is known about the mechanisms for this pain disparity. This study used quantitative sensory testing to assess pain experience in healthy, pain-free adults (nâ¯=â¯137 NAs (87 female), nâ¯=â¯145 non-Hispanic whites (NHW; 68 female)) after painful electric, heat, cold, ischemic, and pressure stimuli. After each stimulus, ratings of pain intensity, sensory pain, affective pain, pain-related anxiety, and situation-specific pain catastrophizing were assessed. The results suggested that NAs reported greater sensory pain in response to suprathreshold electric and heat stimuli, greater pain-related anxiety to heat and ischemic stimuli, and more catastrophic thoughts in response to electric and heat stimuli. Sex differences were also noted; however, with the exception of catastrophic thoughts to cold, these finding were not moderated by race/ethnicity. Together, findings suggest NAs experience heightened sensory, anxiety, and catastrophizing reactions to painful stimuli. This could place NAs at risk for future chronic pain and could ultimately lead to a vicious cycle that maintains pain (eg, painâ¯ââ¯anxiety/catastrophizingâ¯ââ¯pain). PERSPECTIVE: NAs experienced heightened sensory, anxiety, and catastrophizing reactions in response to multiple pain stimuli. Given the potential for anxiety and catastrophic thoughts to amplify pain, this characteristic may place them at risk for pain disorders and could lead to a vicious cycle that maintains pain.