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1.
Carbohydr Polym ; 227: 115361, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31590858

RESUMO

Chicken feather peptone (CFP) derived from poultry waste is a rich source of essential minerals and amino acids. This, along with suitable carbon source, can be used as a low cost complex supplemental nutrient source for microbial fermentation. In the present work, CFP blended with sucrose was evaluated for the production of levan using Bacillus subtilis MTCC 441. Amount of CFP added to the medium significantly influenced levan production and it was found that at a concentration 2 g/L, maximum levan yield of 0.26 ±â€¯0.04 g/g sucrose was obtained. The levan yield obtained with CFP as a low cost supplemental nutrient source was comparable with that obtained from commercial medium (0.31 ±â€¯0.02 g/g sucrose). Levan produced using CFP was tested on primary cell lines at various concentrations (100-1000 µM) and found to be non-toxic and bio-compatible in nature. This indicates that CFP could be used as low cost nutrient source for levan production.


Assuntos
Bacillus subtilis/metabolismo , Frutanos/metabolismo , Peptonas/metabolismo , Sacarose/metabolismo , Animais , Sobrevivência Celular , Galinhas , Plumas/química , Fermentação , Frutanos/farmacologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos
2.
BMC Plant Biol ; 19(1): 591, 2019 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-31881921

RESUMO

BACKGROUND: Sucrose (Suc), as the precursor molecule for rubber biosynthesis in Hevea brasiliensis, is transported via phloem-mediated long-distance transport from leaves to laticifers in trunk bark, where latex (cytoplasm of laticifers) is tapped for rubber. In our previous report, six Suc transporter (SUT) genes have been cloned in Hevea tree, among which HbSUT3 is verified to play an active role in Suc loading to the laticifers. In this study, another latex-abundant SUT isoform, HbSUT5, with expressions only inferior to HbSUT3 was characterized especially for its roles in latex production. RESULTS: Both phylogenetic analysis and subcellular localization identify HbSUT5 as a tonoplast-localized SUT protein under the SUT4-clade (=type III). Suc uptake assay in baker's yeast reveals HbSUT5 to be a typical Suc-H+ symporter, but its high affinity for Suc (Km = 2.03 mM at pH 5.5) and the similar efficiency in transporting both Suc and maltose making it a peculiar SUT under the SUT4-clade. At the transcript level, HbSUT5 is abundantly and preferentially expressed in Hevea barks. The transcripts of HbSUT5 are conspicuously decreased both in Hevea latex and bark by two yield-stimulating treatments of tapping and ethephon, the patterns of which are contrary to HbSUT3. Under the ethephon treatment, the Suc level in latex cytosol decreases significantly, but that in latex lutoids (polydispersed vacuoles) changes little, suggesting a role of the decreased HbSUT5 expression in Suc compartmentalization in the lutoids and thus enhancing the Suc sink strength in laticifers. CONCLUSIONS: Our findings provide insights into the roles of a vacuolar sucrose transporter, HbSUT5, in Suc exchange between lutoids and cytosol in rubber-producing laticifers.


Assuntos
Hevea/metabolismo , Látex/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Plantas/metabolismo , Sacarose/metabolismo , Citoplasma/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Hevea/genética , Floema/metabolismo , Casca de Planta/metabolismo , Regiões Promotoras Genéticas , Saccharomyces cerevisiae , Vacúolos/metabolismo
3.
Plant Physiol Biochem ; 144: 455-465, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31655344

RESUMO

Sugarcane is an important sugar and energy crop worldwide. It utilises highly efficient C4 photosynthesis and accumulates sucrose in its culms. The sucrose content in sugarcane culms is a quantitative trait controlled by multiple genes. The regulatory mechanism underlying the maximum sucrose level in sugarcane culms remains unclear. We used transcriptome sequences to identify the potential regulatory genes involved in sucrose accumulation in Saccarum officinarum L. cv. Badila. The sucrose accumulating internodes at the elongation and mature growth stage and the immature internodes with low sucrose content at the mature stage were used for RNA sequencing. The obtained differentially expressed genes (DEGs) related to sucrose accumulation were analysed. Results showed that the transcripts encoding invertase (beta-fructofuranosidase, EC: 3.2.1.26) which catalyses sucrose hydrolysis and 6-phosphofructokinase (PFK, EC: 2.7.1.11), a key glycolysis regulatory enzyme, were downregulated in the high sucrose accumulation internodes. The transcripts encoding key enzymes for ABA, gibberellin and ethylene synthesis were also downregulated during sucrose accumulation. Furthermore, regulated protein kinase, transcription factor and sugar transporter genes were also obtained. This research can clarify the molecular regulation network of sucrose accumulation in sugarcane.


Assuntos
Saccharum/metabolismo , Sacarose/metabolismo , Transcriptoma/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Saccharum/genética
4.
Mol Cells ; 42(10): 711-720, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31607684

RESUMO

Sink strength optimizes sucrose import, which is fundamental to support developing seed grains and increase crop yields, including those of rice (Oryza sativa). In this regard, little is known about the function of vacuolar invertase (VIN) in controlling sink strength and thereby seed size. Here, in rice we analyzed mutants of two VINs, OsVIN1 and OsVIN2, to examine their role during seed development. In a phenotypic analysis of the T-DNA insertion mutants, only the OsVIN2 mutant osvin2-1 exhibited reduced seed size and grain weight. Scanning electron microscopy analysis revealed that the small seed grains of osvin2-1 can be attributed to a reduction in spikelet size. A significant decrease in VIN activity and hexose level in the osvin2-1 spikelets interfered with spikelet growth. In addition, significant reduction in starch and increase in sucrose, which are characteristic features of reduced turnover and flux of sucrose due to impaired sink strength, were evident in the pre-storage stage of osvin2-1 developing grains. In situ hybridization analysis found that expression of OsVIN2 was predominant in the endocarp of developing grains. A genetically complemented line with a native genomic clone of OsVIN2 rescued reduced VIN activity and seed size. Two additional mutants, osvin2-2 and osvin2-3 generated by the CRISPR/Cas9 method, exhibited phenotypes similar to those of osvin2-1 in spikelet and seed size, VIN activity, and sugar metabolites. These results clearly demonstrate an important role of OsVIN2 as sink strength modulator that is critical for the maintenance of sucrose flux into developing seed grains.


Assuntos
Oryza/enzimologia , Sementes/anatomia & histologia , Sementes/enzimologia , Vacúolos/enzimologia , beta-Frutofuranosidase/metabolismo , Proteína 9 Associada à CRISPR/metabolismo , Sistemas CRISPR-Cas/genética , Metaboloma , Mutação/genética , Tamanho do Órgão , Fotossíntese , Plantas Geneticamente Modificadas , Amido/metabolismo , Sacarose/metabolismo
5.
Enzyme Microb Technol ; 131: 109372, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31615660

RESUMO

Turanose is a natural isomer of sucrose. It is an emerging functional sweetener of the next generation. Turanose is catalytically synthesized from the sucrose biomass by employing amylosucrase enzyme. In this study, a novel gene encoding amylosucrase (Asmet) has been identified from the metagenome of a thermal aquatic habitat. Asmet exhibits 37-55% identity at the protein level with the known amylosucrases characterized till date. Asmet was cloned and expressed in Escherichia coli, followed by protein purification, and characterization. Asmet protein exhibited the maximum total activity at 9.0 pH and 60 °C temperature, whereas, 8.0 pH and 50 °C temperature were found optimum for transglycosylation activity. Asmet showed fairly high thermal tolerance at 50 °C. The conjugation of Asmet protein with functionalized iron nanoparticles significantly improved its thermal tolerance, showing hardly any loss in the enzyme's activity even after 72 h of heat (50 °C) exposure. The turanose yield of about 47% was achieved from 1.5 M sucrose, containing 0.5 M fructose in the reaction. Turanose was purified (˜95%) via a bio-physical process, and characterized by TLC, HPLC, and NMR. The novel amylosucrase gene was demonstrated to be a potential candidate for turanose production, utilizing various sucrose containing feedstocks.


Assuntos
Dissacarídeos/metabolismo , Glucosiltransferases/metabolismo , Metagenoma , Sacarose/metabolismo , Biotransformação , Clonagem Molecular , Estabilidade Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Glucosiltransferases/química , Glucosiltransferases/genética , Concentração de Íons de Hidrogênio , Homologia de Sequência de Aminoácidos , Temperatura Ambiente
6.
Molecules ; 24(19)2019 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-31561523

RESUMO

A convenient and effective sucrose transport assay for Clostridium strains is needed. Traditional methods, such as 14C-sucrose isotope labelling, use radioactive materials and are not convenient for many laboratories. Here, a sucrose transporter from potato was introduced into Clostridium, and a fluorescence assay based on esculin was used for the analysis of sucrose transport in Clostridium strains. This showed that the heterologously expressed potato sucrose transporter is functional in Clostridium. Recombinant engineering of high-level sucrose transport would aid sucrose fermentation in Clostridium strains. The assay described herein provides an important technological platform for studying sucrose transporter function following heterologous expression in Clostridium.


Assuntos
Bioensaio , Clostridium/genética , Clostridium/metabolismo , Expressão Gênica , Proteínas de Membrana Transportadoras/genética , Proteínas de Plantas/genética , Solanum tuberosum/metabolismo , Sacarose/metabolismo , Transporte Biológico , Fluorescência , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Plantas/metabolismo
7.
Int J Mol Sci ; 20(16)2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31395813

RESUMO

Vascular tissues essentially regulate water, nutrient, photo-assimilate, and phytohormone logistics throughout the plant body. Boron (B) is crucial for the development of the vascular tissue in many dicotyledonous plant taxa and B deficiency particularly affects the integrity of phloem and xylem vessels, and, therefore, functionality of long-distance transport. We hypothesize that changes in the plants' B nutritional status evoke differential responses of the vasculature and the mesophyll. However, direct analyses of the vasculature in response to B deficiency are lacking, due to the experimental inaccessibility of this tissue. Here, we generated biochemical and physiological understanding of B deficiency response reactions in common plantain (Plantago major L.), from which pure and intact vascular bundles can be extracted. Low soil B concentrations affected quantitative distribution patterns of various phytohormones, sugars and macro-, and micronutrients in a tissue-specific manner. Vascular sucrose levels dropped, and sucrose loading into the phloem was reduced under low B supply. Phytohormones responded selectively to B deprivation. While concentrations of abscisic acid and salicylic acid decreased at low B supply, cytokinins and brassinosteroids increased in the vasculature and the mesophyll, respectively. Our results highlight the biological necessity to analyze nutrient deficiency responses in a tissue- rather organ-specific manner.


Assuntos
Boro/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/metabolismo , Plantago/metabolismo , Sacarose/metabolismo , Brassinosteroides/metabolismo , Citocininas/metabolismo , Floema/metabolismo , Xilema/metabolismo
8.
Biomed Pharmacother ; 117: 109197, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31387190

RESUMO

Sucrose nonfermenting AMPK-related kinase (SNARK) is a member of the AMPK family of kinases and has been implicated in the regulation of critical metabolic processes. Recent findings demonstrate that SNARK has an important role in the maintenance of muscle mass with age. Loss of skeletal muscle mass (cachexia) is a key problem for cancer patients. Thus, based on our previous findings with aging, we hypothesized that SNARK would play a role in regulating muscle mass under conditions of cancer cachexia. To test this hypothesis, Lewis Lung Carcinoma tumor cells or vehicle were injected subcutaneously in the right flank of wild type mice, muscle-specific transgenic mice expressing inactive SNARK mutant (SDN) or muscle-specific transgenic mice overexpressing wild-type SNARK (SWT). All tumor-bearing mice presented muscle wasting compared to vehicle-injected mice. However, SDN tumor-bearing mice had more pronounced atrophy compared to wild-type and SWT tumor-bearing mice. Histological analysis confirmed muscle atrophy in tumor-bearing mice, and SDN tumor-bearing mice exhibited a significantly smaller skeletal muscle cross-sectional area than wild-type and SWT tumor-bearing mice. Moreover, SDN tumor-bearing mice had increased skeletal muscle BAX protein expression, a marker of apoptosis, compared to other groups.Thus, lack of SNARK in skeletal muscle aggravates cancer-induced skeletal muscle wasting. These findings uncover a role for SNARK in the maintenance of skeletal muscle mass under cachexia conditions.


Assuntos
Carcinoma Pulmonar de Lewis/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Proteínas Serina-Treonina Quinases/metabolismo , Sacarose/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Apoptose/fisiologia , Caquexia/metabolismo , Caquexia/patologia , Carcinoma Pulmonar de Lewis/complicações , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Atrofia Muscular/etiologia
9.
Curr Microbiol ; 76(11): 1238-1246, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31377819

RESUMO

Streptococcus mutans (S. mutans) adheres to the tooth surface, metabolizes carbohydrates, and produces acid products, leading to enamel demineralization-the onset of dental caries. Rapid acidification by S. mutans has been observed in the presence of glucose. However, little is known about the role of small RNAs (sRNAs) in S. mutans in the presence of glucose and their relationship to tooth adherence. The objective of this study was to evaluate the role of sRNAs in S. mutans (18-50 nucleotides) regarding adherence capacity under 1% and 5% glucose concentrations. The pH drop and adherence capacity in the 1% glucose condition were similar to these parameters under conditions of 5% sucrose that were published in our previous study. A total of 2149 candidate sRNA with at least 100 average reads in the 5% and 1% glucose libraries were obtained. Between the two libraries, 581 sRNAs were differentially expressed and 43 sRNAs were verified. However, the expression levels of the predicted target genes gtfC and spaP were similar between the 1% and 5% glucose conditions. The bioinformatic analysis suggested that differentially expressed sRNAs may be involved in several pathways. These findings indicate that sRNAs were induced under these glucose concentrations and a series of sRNAs were specifically induced, respectively. sRNAs that are induced under glucose stress may be involved in regulating adherence of S. mutans.


Assuntos
Aderência Bacteriana , Glucose/análise , RNA Bacteriano/metabolismo , Streptococcus mutans/fisiologia , Cárie Dentária/microbiologia , Regulação Bacteriana da Expressão Gênica , Glucose/metabolismo , Humanos , RNA Bacteriano/genética , Streptococcus mutans/genética , Streptococcus mutans/crescimento & desenvolvimento , Sacarose/metabolismo
10.
Nutrients ; 11(8)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374985

RESUMO

BACKGROUND: In light of obesity, replacing sugar with non-nutritive sweeteners is commonly used to reduce sugar content of food products. This study aimed to compare human energy expenditure (EE), carbohydrate oxidation and food intake after the ingestion of test foods sweetened with sucrose or a non-nutritive sweetener. METHODS: This was an acute crossover feeding study that entailed consumption of three test foods: jelly sweetened with 50 g sucrose (SUCROSE), with 120 mg of sucralose only (NNS), or 120 mg sucralose but matched in carbohydrate with 50 g maltodextrin (MALT). On test days, participants arrived at the research facility after an overnight fast. Resting energy expenditure (indirect calorimeter) was measured for 30 min followed by jelly consumption. Participants' EE and substrate oxidation were measured for 90 min subsequently. After EE assessment, participants completed a meal challenge before leaving the research facility, and recorded food intake for the remaining day. Subjective appetite ratings were assessed before and after test foods and meal challenge. RESULTS: Eleven participants completed the study. EE was higher in SUCROSE and MALT than NNS, but not statistically significant. Carbohydrate oxidation was SUCROSE > MALT > NNS (p < 0.001). Earlier and bigger rise in carbohydrate oxidation was observed in SUCROSE than MALT, although both were carbohydrate-matched. NNS did not promote energy expenditure, carbohydrate oxidation or stimulate appetite. CONCLUSIONS: Foods sweetened with sucrose or non-nutritive sweeteners but matched in carbohydrate content have different effects on human EE and carbohydrate oxidation. Sucralose alone did not affect EE, but lower energy in the test food from sugar replacement was eventually fully compensated. Findings from this pilot study should be verified with bigger clinical studies in the future to establish clinical relevance.


Assuntos
Regulação do Apetite/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Adoçantes não Calóricos/administração & dosagem , Sacarose/análogos & derivados , Adolescente , Adulto , Idoso , Estudos Cross-Over , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adoçantes não Calóricos/metabolismo , Oxirredução , Projetos Piloto , Sacarose/administração & dosagem , Sacarose/metabolismo , Adulto Jovem
11.
World J Microbiol Biotechnol ; 35(9): 136, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31432249

RESUMO

Volatile phenols such as 4-ethylphenol are produced from hydroxycinnamic acids by Dekkera bruxellensis, an important yeast contaminating alcoholic fermentations. 4-ethylphenol results from the decarboxylation and reduction of p-coumaric acid, a compound found in sugarcane musts. In wine, volatile phenols are responsible by sensorial alterations whereas in the context of bioethanol fermentation, little is known about their effects on the main yeast, Saccharomyces cerevisiae. Here we evaluated the interaction of 4-ethylphenol and pH, sucrose and ethanol on the growth and fermentation capacity of the industrial strain of S. cerevisiae PE-2. A central compound rotational design was utilized to evaluate the effect of 4-ethylphenol, pH, ethanol and sucrose concentration on the yeast maximum specific growth rate (µmax) in microplate experiments in YPS medium (Yeast extract-Peptone-Sucrose), at 30 °C. Following, single-cycle fermentations in YPS medium, pH 4.5, 17% sucrose, at 30 °C, with 4-ethylphenol in concentrations of 10 and 20 mg L-1 being added at the start or after 4 h of fermentation, were carried out. 4-ethylphenol affected µmax of S. cerevisiae in situations that resemble the conditions of industrial bioethanol production, especially the low pH of the fermentation medium and the high ethanol concentration because of the anaerobic sucrose uptake. The addition of 4-ethylphenol on fermentation resulted in significant effect on the cell yeast concentration, pH and alcohol production, with significant decrease from 86% to the range of 65-74% in the fermentative efficiency. The industrial yeast S. cerevisiae PE-2 growth and fermentative capacity were affected by the presence of 4-ethylphenol, a metabolite produced by D. bruxellensis, which may contribute to explain the impact of this yeast on bioethanol industrial production.


Assuntos
Etanol/metabolismo , Fermentação , Microbiologia Industrial , Fenóis/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Sacarose/metabolismo , Meios de Cultura/química , Inibidores do Crescimento/metabolismo , Concentração de Íons de Hidrogênio , Saccharomyces cerevisiae/efeitos dos fármacos , Temperatura Ambiente
12.
Int J Mol Sci ; 20(16)2019 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-31405215

RESUMO

In family GH13 of the carbohydrate-active enzyme database, subfamily 18 contains glycoside phosphorylases that act on α-sugars and glucosides. Because their phosphorolysis reactions are effectively reversible, these enzymes are of interest for the biocatalytic synthesis of various glycosidic compounds. Sucrose 6F-phosphate phosphorylases (SPPs) constitute one of the known substrate specificities. Here, we report the characterization of an SPP from Ilumatobacter coccineus with a far stricter specificity than the previously described promiscuous SPP from Thermoanaerobacterium thermosaccharolyticum. Crystal structures of both SPPs were determined to provide insight into their similarities and differences. The residues responsible for binding the fructose 6-phosphate group in subsite +1 were found to differ considerably between the two enzymes. Furthermore, several variants that introduce a higher degree of substrate promiscuity in the strict SPP from I. coccineus were designed. These results contribute to an expanded structural knowledge of enzymes in subfamily GH13_18 and facilitate their rational engineering.


Assuntos
Actinobacteria/enzimologia , Fosforilases/metabolismo , Sacarose/metabolismo , Thermoanaerobacterium/enzimologia , Actinobacteria/química , Actinobacteria/metabolismo , Cristalografia por Raios X , Modelos Moleculares , Fosforilases/química , Conformação Proteica , Especificidade por Substrato , Thermoanaerobacterium/química , Thermoanaerobacterium/metabolismo
13.
Appl Microbiol Biotechnol ; 103(19): 7953-7969, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31407037

RESUMO

Two sustainable and cost-effective cascade enzymatic systems were developed to regenerate uridine diphosphate (UDP)-α-D-glucose and UDP-ß-L-rhamnose from sucrose. The systems were coupled with the UDP generating glycosylation reactions of UDP sugar-dependent glycosyltransferase (UGT) enzymes mediated reactions. As a result, the UDP generated as a by-product of the GT-mediated reactions was recycled. In the first system, YjiC, a UGT from Bacillus licheniformis DSM 13, was used for transferring glucose from UDP-α-D-glucose to naringenin, in which AtSUS1 from Arabidopsis thaliana was used to synthesize UDP-α-D-glucose and fructose as a by-product from sucrose. In the second system, flavonol 7-O-rhamnosyltransferase (AtUGT89C1) from A. thaliana was used to transfer rhamnose from UDP-ß-L-rhamnose to quercetin, in which AtSUS1 along with UDP-ß-L-rhamnose synthase (AtRHM1), also from A. thaliana, were used to produce UDP-ß-L-rhamnose from the same starter sucrose. The established UDP recycling system for the production of naringenin glucosides was engineered and optimized for several reaction parameters that included temperature, metal ions, NDPs, pH, substrate ratio, and enzymes ratio, to develop a highly feasible system for large-scale production of different derivatives of naringenin and other natural products glucosides, using inexpensive starting materials. The developed system showed the conversion of about 37 mM of naringenin into three different glucosides, namely naringenin, 7-O-ß-D-glucoside, naringenin, 4'-O-ß-D-glucoside, and naringenin, 4',7-O-ß-D-diglucoside. The UDP recycling (RCmax) was 20.10 for naringenin glucosides. Similarly, the conversion of quercetin to quercetin 7-O-α-L-rhamnoside reached a RCmax value of 10.0.


Assuntos
Flavanonas/metabolismo , Glucosídeos/metabolismo , Glucuronosiltransferase/metabolismo , Hexosiltransferases/metabolismo , Quercetina/metabolismo , Sacarose/metabolismo , Arabidopsis/enzimologia , Bacillus licheniformis/enzimologia , Biocatálise , Glucuronosiltransferase/isolamento & purificação , Hexosiltransferases/isolamento & purificação
14.
Plant Physiol Biochem ; 142: 440-451, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31419646

RESUMO

Drought stress during the grain filling stage severely affects the quality and quantity of starch in rice grains. The enzymes such as ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27) and starch synthase (SS, EC 2.4.1.21) are the key regulatory enzymes involved in the starch biosynthesis. In this study, the activity of the AGPase and starch synthase (SS) was correlated with the qualitative and quantitative parameters such as sucrose, starch, amylose, amylopectin, and resistant starch in leaves, roots, and grains of drought tolerant (N22) and drought susceptible (IR64) cultivars under applied water deficit stress (WDS). Drought stress enhanced the remobilization of stored starch from leaves to developing rice grains which was positively correlated with a decrease in the starch and starch synthase activity in leaves. Starch accumulation in developing grains was positively correlated with an increase in the AGPase and SS activity under drought. It was found that starch, amylopectin, and sucrose content in developing grains increased under water deficit stress (WDS), while amylose content decreased in both the varieties. However, in leaves, the SS activity decreased while AGPase activity was found to be increased under WDS in both varieties. Decreased starch content in matured grains was due to shortening of grain filling stage as drought stress caused early plant senescence. Yield reduction under drought was more in susceptible variety IR64 as compared to tolerant genotype N22.


Assuntos
Grão Comestível/metabolismo , Oryza/metabolismo , Amido/metabolismo , Amilopectina/metabolismo , Amilose/metabolismo , Desidratação , Grão Comestível/fisiologia , Oryza/fisiologia , Fotossíntese , Folhas de Planta/metabolismo , Sacarose/metabolismo
15.
Enzyme Microb Technol ; 130: 109364, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31421727

RESUMO

A high yielding and straightforward production system of fructooligosaccharide (FOS) was developed for industrial production of prebiotics. To increase conversion yield of FOS from sucrose, recombinant yeast secreting inulosucrase from Lactobacillus reuteri (LrInu) were constructed. Efficient secretion of LrInu was achieved by truncation of both amino- and carboxy-termini (LrInuΔNC) and by introducing an optimal secretion signal. The recombinant yeast produced 220 U/mL of recombinant LrInuΔNC into culture medium during fed-batch fermentation. By direct fermentation of recombinant yeast in medium containing sucrose, 128.4 g/L of FOS was produced with 85.6% conversion yield from 300 g/L sucrose, and the highest titer was 152.6 g/L from 400 g/L sucrose. The degree of polymerization of generated FOS was 2-20 indicating medium chain (mcFOS) range. This is the first report of industrially applicable production of mcFOS by recombinant yeast secreting bacterial inulosucrase.


Assuntos
Fermentação , Hexosiltransferases/metabolismo , Lactobacillus reuteri/enzimologia , Oligossacarídeos/metabolismo , Saccharomyces cerevisiae/genética , Microbiologia Industrial , Lactobacillus reuteri/genética , Recombinação Genética , Saccharomyces cerevisiae/metabolismo , Sacarose/metabolismo
16.
Phytochemistry ; 167: 112086, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31450092

RESUMO

The worldwide-cultivated chicory (Cichorium intybus L.) produces food and beneficial compounds, and young pre-flowering inflorescence stems are newly marketed vegetables. These sink-organs undergo growth by metabolizing sugars of leaf origin; the carbohydrate content and sweetness are crucial aspects for consumers' nutrition and acceptance. NMR profiling of 31 hydrosoluble phytochemicals showed that stem contents varied as influenced by genotype, environment and interaction, and that higher sucrose levels were associated with the sweeter of two landraces. Integrative analyses of metabolic and transcriptomic profile variations allowed the dissection of sucrose pathway. Overall, 427 and 23 unigenes respectively fell into the categories of sucrose metabolism and sugar carriers. Among 10 differentially expressed genes, the 11474/sucrose synthase, 53458/fructokinase, 9306 and 17035/hexokinases, and 20171/SWEET-type genes significantly associated to sugar content variation, and deduced proteins were characterised in silico. Correlation analyses encompassing sugar level variation, expressions of the former genes and of computationally assigned transcription factors (10938/NAC, 14712/bHLH, 40133/TALE and 17846/MIKC) revealed a gene network. The latter was minimally affected by the environment and accomplished with markers, representing a resource for biological studies and breeding.


Assuntos
Chicória/genética , Chicória/metabolismo , Perfilação da Expressão Gênica , Metabolômica , Caules de Planta/metabolismo , Sacarose/metabolismo , Redes Reguladoras de Genes/genética , Genes de Plantas/genética
17.
Planta ; 250(5): 1743-1755, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31422508

RESUMO

MAIN CONCLUSION: In alfalfa, the B form of Sucrose phosphate synthase synthesizes sucrose in the leaves while the A form participates in regulatory cycles of synthesis/breakdown of sucrose/starch in the root nodules. Sucrose (Suc) is the major stable product of photosynthesis that is transported to all heterotrophic organs as a source of energy and carbon. The enzyme sucrose phosphate synthase (SPS) catalyzes the synthesis of Suc. Besides the leaves, SPS is also found in heterotrophic organs. There are two isoforms of SPS in alfalfa (Medicago sativa): SPSA and SPSB. While SPSA is expressed in the vasculature of all the organs and in the N2-fixing zone in the nodules, SPSB is exclusively expressed in the photosynthetic cells. Two classes of alfalfa transformants were produced, one with a gene construct consisting of the alfalfa SPSA promoter and the other with the SPSB promoter-both driving the maize SPS coding region-referred to as SPSA-ZmSPS and SPSB-ZmSPS, respectively. Both classes of transformants showed increased growth compared to control plants. The SPSB-ZmSPS transformants showed increased SPS protein levels and activity along with a significant increase in the Suc levels in the leaves. The SPSA-ZmSPS transformants showed an increase in the SPS protein level and enzyme activity both in the leaves and the nodules with no increase in Suc content in the leaves but a substantial increase in the nodules. Both SPSA and SPSB have unique roles in the nodules (sink) and leaves (source). SPSB is responsible for the synthesis of Suc in the photosynthetic cells and SPSA participates in a regulatory cycle in which Suc is simultaneously degraded and re-synthesized; both these functions contribute to plant growth in rhizobia nodulated alfalfa plants.


Assuntos
Carbono/metabolismo , Glucosiltransferases/metabolismo , Medicago sativa/enzimologia , Amido/metabolismo , Sacarose/metabolismo , Genes Reporter , Glucosiltransferases/genética , Medicago sativa/genética , Fotossíntese , Folhas de Planta/enzimologia , Folhas de Planta/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas/genética , Nódulos Radiculares de Plantas/enzimologia , Nódulos Radiculares de Plantas/genética
18.
J Agric Food Chem ; 67(35): 9738-9748, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31411877

RESUMO

The presence of chromium (Cr) in cultivated fields affects carbohydrate metabolism of rice (Oryza sativa L.) and weakens its productivity. Little is known about the molecular mechanism of sucrose metabolism underlying Cr stress response in rice plants. In the present study, the transcriptome map of sucrose metabolism in rice seedlings exposed to both trivalent and hexavalent chromium was investigated using Agilent 4 × 44K rice microarray analysis. Results indicated that Cr exposure (3 days) significantly (p < 0.05) improved sucrose accumulation, and altered the activities of sucrose synthetase, sucrose phosphate phosphatase, and amylosynthease in rice tissues. We identified 119 differentially regulated genes involved in 17 sucrose metabolizing enzymes and found that gene responses in roots were significantly (p < 0.05) stronger than in shoots under both Cr(III) and Cr(VI) treatment. The network maps of gene regulation responsible for sucrose metabolism in rice plants provide a theoretical basis for further cultivating Cr-resistant rice cultivars through molecular genetic improvement.


Assuntos
Cromo/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Oryza/metabolismo , Poluentes do Solo/farmacologia , Sacarose/metabolismo , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Oryza/efeitos dos fármacos , Oryza/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo
19.
J Plant Physiol ; 240: 153016, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400718

RESUMO

Sucrose metabolism is believed to have a central role in promoting sink strength and sucrose storage in the sugarbeet taproot. How sucrose accumulation is increased by sucrose-degrading enzymes, however, is a paradox. To elucidate roles for sucrose-degrading activities in sucrose accumulation, relationships between the intercellular location of sucrose-catabolizing enzymes and sites of sucrose accumulation were determined in the sugarbeet taproot. Sucrose storage was evident in parenchyma cells of the outer cortex, rays, and rings of parenchyma tissue, but was absent in phloem, the vascular cambium, cells surrounding these tissues, or cells surrounding xylem. Sucrose synthase, which was primarily responsible for sucrose catabolism throughout the taproot, was expressed in similar cell and tissue types to those accumulating sucrose. Colocalization of sucrose synthase with sucrose accumulation, as well as sucrose synthase localization near the tonoplast, suggests a role for the enzyme in generating metabolic energy to fuel sucrose sequestration in the vacuole. Localization near the plasma membrane also suggests a role for sucrose synthase in supplying substrates for cell wall biosynthesis. By utilizing sucrose for ATP or cell wall biosynthesis, sucrose synthase likely maintains the source-to-sink sucrose gradient that drives sucrose transport into the root, thereby promoting sugarbeet root sink strength.


Assuntos
Beta vulgaris/genética , Beta vulgaris/metabolismo , Glucosiltransferases/genética , Raízes de Plantas/metabolismo , Sacarose/metabolismo , Beta vulgaris/ultraestrutura , Glucosiltransferases/metabolismo , Microscopia Eletrônica de Transmissão , Raízes de Plantas/ultraestrutura
20.
Int J Mol Sci ; 20(15)2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31382384

RESUMO

Numerous studies have demonstrated the potential of sugar beet to lose the final sugar yield under water limiting regime. Ample evidences have revealed the important role of mineral nutrition in increasing plant tolerance to abiotic stresses. Despite the vital role of calcium (Ca2+) in plant growth and development, as well as in stress responses as an intracellular messenger, its role in alleviating drought stress in sugar beet has been rarely addressed. Here, an attempt was undertaken to investigate whether, and to what extent, foliar application of Ca2+ confers drought stress tolerance in sugar beet plants exposed to drought stress. To achieve this goal, sugar beet plants, which were grown in a high throughput phenotyping platform, were sprayed with Ca2+ and submitted to drought stress. The results showed that foliar application of Ca2+ increased the level of magnesium and silicon in the leaves, promoted plant growth, height, and leaf coverage area as well as chlorophyll level. Ca2+, in turn, increased the carbohydrate levels in leaves under drought condition and regulated transcriptionally the genes involved in sucrose transport (BvSUC3 and BvTST3). Subsequently, Ca2+ enhanced the root biomass and simultaneously led to induction of root (BvSUC3 and BvTST1) sucrose transporters which eventually supported the loading of more sucrose into beetroot under drought stress. Metabolite analysis revealed that the beneficial effect of Ca2+ in tolerance to drought induced-oxidative stress is most likely mediated by higher glutathione pools, increased levels of free polyamine putrescine (Put), and lower levels of amino acid gamma-aminobutyric acid (GABA). Taken together, this work demonstrates that foliar application of Ca2+ is a promising fertilization strategy to improve mineral nutrition efficiency, sugar metabolism, redox state, and thus, drought stress tolerance.


Assuntos
Beta vulgaris/fisiologia , Cálcio/metabolismo , Raízes de Plantas/fisiologia , Sacarose/metabolismo , Aclimatação , Beta vulgaris/crescimento & desenvolvimento , Biomassa , Secas , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Raízes de Plantas/crescimento & desenvolvimento , Estresse Fisiológico
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