Functional analysis on sucrose transporters in sweet potato / 生物工程学报

Sweet potato is an important food crop that can also be used as an industrial raw material. Sucrose is the main form of long-distance carbohydrate transport in plants, and sucrose transporter (SUT) regulates the transmembrane transport and distribution of sucrose during plant growth and metabolism. Moreover, SUT plays a key role in phloem mediated source-to-sink sucrose transport and physiological activities, supplying sucrose for the sink tissues. In this study, the full-length cDNA sequences of IbSUT62788 and IbSUT81616 were obtained by rapid amplification of cDNA ends (RACE) cloning according to the transcripts of the two SUT coding genes which were differentially expressed in sweet potato storage roots with different starch properties. Phylogenetic analysis was performed to clarify the classification of IbSUT62788 and IbSUT81616. The subcellular localization of IbSUT62788 and IbSUT81616 was determined by transient expression in Nicotiana benthamiana. The function of IbSUT62788 and IbSUT81616 in sucrose and hexose absorption and transport was identified using yeast functional complementarity system. The expression pattern of IbSUT62788 and IbSUT81616 in sweet potato organs were analyzed by real-time fluorescence quantitative PCR (RT-qPCR). Arabidopsis plants heterologous expressing IbSUT62788 and IbSUT81616 genes were obtained using floral dip method. The differences in starch and sugar contents between transgenic and wild-type Arabidopsis were compared. The results showed IbSUT62788 and IbSUT81616 encoded SUT proteins with a length of 505 and 521 amino acids, respectively, and both proteins belonged to the SUT1 subfamily. IbSUT62788 and IbSUT81616 were located in the cell membrane and were able to transport sucrose, glucose and fructose in the yeast system. In addition, IbSUT62788 was also able to transport mannose. The expression of IbSUT62788 was higher in leaves, lateral branches and main stems, and the expression of IbSUT81616 was higher in lateral branches, stems and storage roots. After IbSUT62788 and IbSUT81616 were heterologously expressed in Arabidopsis, the plants grew normally, but the biomass increased. The heterologous expression of IbSUT62788 increased the soluble sugar content, leaf size and 1 000-seed weight of Arabidopsis plants. Heterologous expression of IbSUT81616 increased starch accumulation in leaves and root tips and 1 000-seed weight of seeds, but decreased soluble sugar content. The results obtained in this study showed that IbSUT62788 and IbSUT81616 might be important genes regulating sucrose and sugar content traits in sweet potato. They might carry out physiological functions on cell membrane, such as transmembrane transport of sucrose, sucrose into and out of sink tissue, as well as transport and unloading of sucrose into phloem. The changes in traits result from their heterologous expression in Arabidopsis indicates their potential in improving the yield of other plants or crops. The results obtained in this study provide important information for revealing the functions of IbSUT62788 and IbSUT81616 in starch and glucose metabolism and formation mechanism of important quality traits in sweet potato.

Perception and sensory acceptance of sweet taste by individuals that who work/study on different shifts / Percepção e aceitação sensorial do gosto doce por indivíduos que trabalham/estudam em diferentes turnos

ABSTRACT Objective This study aimed to evaluate the perception and sensory acceptance of sweet taste by individuals who work/study on different shifts. Methods Three groups of individuals were recruited: the Control group (individuals that study during the day and do not work at night), Group 1 (individuals that study in the evening) and Group 2 (individuals that work overnight). The individuals were submitted to a detection threshold test using sucrose solutions and a sensory acceptance test using a structured hedonic scale and a Just-About-Right scale for sweet taste in blancmange. Results The detection thresholds were significantly higher for Groups 1 and 2. Individuals of Group 2 had a preference by blancmanges when having high sucrose concentrations, as well as had an ideal concentration of 10.50% sucrose against 5.95% sucrose for the Control group. Conclusion Our study shows a relationship between changes in the circadian cycle and the sensory perception and acceptance of sweet taste. More studies need to be performed to understand such relationships and their repercussions better.

RESUMO Objetivo O objetivo deste estudo foi avaliar a percepção e a aceitação sensorial do gosto doce por indivíduos que trabalham/estudam em diferentes turnos. Métodos Foram recrutados três grupos de indivíduos: Grupo Controle (indivíduos que estudam durante o dia e não trabalham à noite), Grupo 1 (indivíduos que estudam à noite) e Grupo 2 (indivíduos que trabalham de madrugada). Os indivíduos foram submetidos ao teste de limiar de detecção utilizando soluções de sacarose e aos testes de aceitação sensorial utilizando escala hedônica estruturada e escala do ideal para o gosto doce em manjar branco. Resultados Os limiares de detecção foram significativamente maiores para os Grupos 1 e 2, sendo certo que os indivíduos do Grupo 2 tiveram preferência pelos manjares com altas concentrações de sacarose, assim como apresentaram uma concentração ideal de 10,50% de sacarose contra 5,95% de sacarose para o grupo Controle. Conclusão Este estudo mostra uma relação entre mudanças no ciclo circadiano e a percepção e a aceitação sensorial do gosto doce, mostrando que estudos mais aprofundados precisam ser realizados para entender melhor tais relações e suas repercussões.

Structural organization of dental biofilm formed in situ in the presence of sucrose associated to maltodextrin

Abstract Maltodextrins, derived from corn starch, have been added to industrialized food combined with sucrose. However it is not clear the diffusion properties of the dental biofilm matrix and the tridimensional structure of multispecies biofilms formed in the presence of these carbohydrates. Therefore, the aim of study was to investigate by confocal laser scanning microscopy (CLSM) the structural organization of the multispecies dental biofilm formed in situ under exposure to sucrose associated to maltodextrin. Adult volunteers wore an intraoral palatal appliance containing bovine enamel blocks. They were instructed to remove the appliance 8 times per day and drop the following solutions on the enamel blocks: deionized distilled water (DDW), maltodextrin, sucrose + maltodextrin or sucrose. Biofilms formed were stained and the percentage of extracellular polysaccharide (%EPS) and thickness were determined by CLSM. Biofilm formed in the presence of sucrose and sucrose + maltodextrin presented similar %EPS and higher than DDW and maltodextrin. Regarding to the biofilm thickness, sucrose and sucrose + maltodextrin treatments were thicker than DDW and maltodextrin and similar between them. The structural organization of the multispecies dental biofilm formed in situ in the presence of sucrose does not change when this carbohydrate is associated to maltodextrin.

Resumo Maltodextrinas, derivadas do amido de milho, tem sido adicionadas a alimentos industrializados combinadas à sacarose. Entretanto não estão esclarecidas as propriedades de difusão na matriz do biofilme dental e a estrutura tridimensional de biofilmes multiespécies formados na presença destes carboidratos. Portanto o objetivo deste estudo foi avaliar, através da microscopia confocal de escaneamento a laser (MCEL), a organização estrutural do biofilme dentário multiespécie formado in situ exposto à sacarose associada a maltodextrina. Voluntários adultos utilizaram dispositivos intraorais palatinos contendo blocos de esmalte bovino. Eles foram instruídos a remover os dispositivos 8 vezes por dia e gotejar as seguintes soluções sobre os blocos de esmalte: água destilada e deionizada (ADD), maltodextrina, sacarose+maltodextrina ou sacarose. Os biofilmes formados foram corados e o percentual de polissacarídeos extracelulares (%PEC) e suas espessuras foram determinados através da MCEL. Os biofilmes formados na presença de sacarose e sacarose+maltodextrina apresentaram os %PEC similares entre si, entretanto maiores do que os grupos submetidos a ADD e maltodextrina. Em relação à espessura do biofilme formado, os tratamentos sacarose e sacarose+maltodextrina apresentaram espessuras similares entre si, e maiores quando comparados aos grupos ADD e maltodextrina. A organização estrutural do biofilme dentário multiespécie formado in situ na presença de sacarose não é alterado quando este carbiodrato é associado a maltodextrina.

Cryopreservation at -75 °C of Agaricus subrufescens on wheat grains with sucrose

Abstract Agaricus subrufescens is a basidiomycete which is studied because of its medicinal and gastronomic importance; however, less attention has been paid to its preservation. This study aimed to evaluate the effect of sucrose addition to substrate and cryotube on the viability of Agaricus subrufescens cryopreserved at -20 °C and at -75 °C for one and two years. Zero, 10% or 20% sucrose was added to potato dextrose agar or wheat grain. The mycelia were cryopreserved in the absence of cryoprotectant or with sucrose solutions at 15%, 30% or 45%. After one or two years at -75 °C or at -20 °C, mycelia were thawed and evaluated about viability, initial time of growth, colony diameter and genomic stability. Cryopreservation at -20 °C is not effective to keep mycelial viability of this fungus. Cryopreservation at -75 °C is effective when sucrose is used in substrates and/or cryotubes. Without sucrose, cryopreservation at -75 °C is effective only when wheat grains are used. Physiological characteristic as mycelial colony diameter is negatively affected when potato dextrose agar is used and unaffected when wheat grain is used after two-year cryopreservation at -75 °C. The fungus genome does not show alteration after two-year cryopreservation at -75 °C.

Efficient production of pullulan by Aureobasidium pullulans grown on mixtures of potato starch hydrolysate and sucrose

Abstract Pullulan is a natural exopolysaccharide with many useful characteristics. However, pullulan is more costly than other exopolysaccharides, which limits its effective application. The purpose of this study was to adopt a novel mixed-sugar strategy for maximizing pullulan production, mainly using potato starch hydrolysate as a low-cost substrate for liquid-state fermentation by Aureobasidium pullulans. Based on fermentation kinetics evaluation of pullulan production by A. pullulans 201253, the pullulan production rate of A. pullulans with mixtures of potato starch hydrolysate and sucrose (potato starch hydrolysate:sucrose = 80:20) was 0.212 h−1, which was significantly higher than those of potato starch hydrolysate alone (0.146 h−1) and mixtures of potato starch hydrolysate, glucose, and fructose (potato starch hydrolysate:glucose:fructose = 80:10:10, 0.166 h−1) with 100 g L−1 total carbon source. The results suggest that mixtures of potato starch hydrolysate and sucrose could promote pullulan synthesis and possibly that a small amount of sucrose stimulated the enzyme responsible for pullulan synthesis and promoted effective potato starch hydrolysate conversion effectively. Thus, mixed sugars in potato starch hydrolysate and sucrose fermentation might be a promising alternative for the economical production of pullulan.

Scaling-up batch conditions for efficient sucrose hydrolysis catalyzed by an immobilized recombinant Pichia pastoris cells in a stirrer tank reactor

Background: Invert sugar is used greatly in food and pharmaceutical industries. This paper describes scaling-up batch conditions for sucrose inversion catalyzed by the recombinant Pichia pastoris BfrA4X whole cells expressing Thermotoga maritima invertase entrapped in calcium alginate beads. For the first time, we describe the application of a kinetic model to predict the fractional conversion expected during sucrose hydrolysis reaction in both, a model and a prototype bioreactor with 0.5- and 5-L working volume, respectively. Results: Different scaled-up criteria used to operate the 0.5-L bioreactor were analyzed to explore the invert sugar large scale production. After model inversion studies, a 5-L scaled-up reaction system was performed in a 7-L stirred reactor. Both scaled-up criteria, immobilized biocatalyst dosage and stirring speed, were analyzed in each type of bioreactors and the collected data were used to ensure an efficient scale-up of this biocatalyst. Conclusions: To date, there is not enough information to describe the large-scale production of invert sugar using different scaled-up criteria such as dose of immobilized biocatalyst and stirring speed effect on mass transfer. The present study results constitute a valuable tool to successfully carry out this type of high-scale operation for industrial purposes.

Effect of carbon source on production, characterization and bioactivity of exopolysaccharide produced by Phellinus vaninii Ljup

ABSTRACT The effect on different three carbon source (i.e. glucose, fructose and sucrose) on production, chemical characterization and antioxidant activity of exopolysaccharide (EPS) produced by Phellinus vaninii Ljup was investigated in this study. Amongst carbon sources examined, glucose and sucrose were favorable for the mycelia growth, while the maximum EPS yield was achieved when sucrose was employed. The predominant carbohydrate compositions in EPSs identified were gluconic acid, glucose, mannose and galactose acid. Then, FT-IR spectral analysis revealed prominent characteristic groups in EPSs. EPSs molecule exist as nearly globular shape form in aqueous solution. The variation also affects antioxidant activities by investigated by using hydroxyl and DPPH radical scavenging assay. Sucrose was best carbon source from the viewpoint of antioxidant activity due to the relatively high contents of galactose in the EPS with moderate molecular weight and polydispersity.

Double mutation of Saccharomyces cerevisiae for enhanced β-D-fructofuranosidase fructohydrolase productivity and application of growth kinetics for parametric significance analysis

Abstract The kinetics of an extracellular β-D-fructofuranosidase fructohydrolase production by Saccharomyces cerevisiae in a chemically defined medium, i.e., sucrose peptone agar yeast extract at pH 6, was investigated. The wild-type was treated with a chemical mutagen, methyl methane sulfonate. Among the six mutants isolated, methyl methane sulfonate-V was found to be a better enzyme producing strain (52 ± 2.4a U/mL). The maximum production (74 ± 3.1a U/mL) was accomplished after at 48 h (68 ± 2.7a mg/mL protein). The mutants were stabilized at low levels of 5-fluoro-cytocine and the viable ones were further processed for optimization of cultural conditions and nutritional requirements. The sucrose concentration, incubation period and pH were optimized to be 30 g/L, 28 °C, and 6.5, respectively. The methyl methane sulfonate-V exhibited an improvement of over 10 folds in enzyme production when 5 g/L ammonium sulfate was used as a nitrogen source. Thin layer chromatography and high-performance liquid chromatography analysis illustrated the optimal enzyme activity supported by the higher rate of hydrolysis of sucrose into monosaccharides, particularly α-D-glucose and β-D-fructose. The values for Qp (2 ± 0.12c U/mL/h) and Yp/s (4 ± 1.24b U/g) of the mutant were considerably increased in comparison with other yeast strains (both isolates and viable mutants). The mutant could be exploited for enzyme production over a wider temperature range (26–34 °C), with significantly high enzyme activity (LSD 0.048, HS) at the optimal temperature.

Effect of carbon and nitrogen sources on in vitro flower and fruit formation and withanolides production in Withania somnifera (L.) Dunal.

We studied the influence of sucrose and nitrogen concentration on in vitro flowering and fruit setting in elongated shoots of Withania somnifera. BA (1.5 mg/l) and IAA (0.3 mg/l) on MS medium supplemented with 4% sucrose showed 67% of in vitro flower induction frequency, 9 flowers/shoot, 4 fruits/shoot and 11 seeds/fruit in elongated-shoots. Different concentrations of nitrogen sources (L-glutamine, adenine sulphate, ammonium nitrate, potassium nitrate and sodium nitrate 5-25 mg/l) were tested in combination with 4% sucrose and BA at 1.5 mg/l and IAA at 0.3 mg/l. Highest number of flowers (20 flowers/shoot; 2.2-fold) and fruits (16 fruits/shoot; 3.39-fold), fruit setting (12 seeds/fruit; 1.08-fold) at a higher frequency (88 %) were achieved on MS medium augmented with 15 mg/l adenine sulphate with same PGRs and sucrose concentration. The maximum production of withanolide A (0.68 mg/g DW) and withanolide B (0.77 mg/g DW) was recorded in in vitro fruits. Highest accumulation of withaferin A (2 mg/g DW) was quantified from in vitro flowers, whereas, it was low in in vitro fruits (0.49 mg/g DW withaferin A). However, withanone (0.23 mg/g DW) was found accumulated uniformly in both in vitro flowers and fruits compared to control.

Levans production by Gluconacetobacter diazotrophicus

Background: Growth of Gluconacetobacter diazotrophicus with glucose as carbon an energy source has been extensively studied. However, there are no reports in the literature describing growth of G. diazotrophicus in cultures containing sucrose as carbon source. The first step in sucrose pathway and production of levans was investigated. Biomass, levans, gluconic acid and keto gluconic acids production and levansucrase activity were determined in cultures with different sucrose concentration and nitrogen sources. Results: The biomass production was maximal in cultures containing 100 g x L-1 sucrose and inorganic nitrogen. Gluconic acid production was observed under all conditions tested, at levels up to 9 g x L-1 in cultures with sucrose excess and biological N2-fixation (BNF). Keto gluconic acids were detectable only in cultures with sucrose excess and supplemented with organic nitrogen sources. Levans production, although observed in all cultures, was maximal in batch culture with 100 g x L-1 of sucrose and BNF, concomitant with a significant expression of extracellular levansucrase. Conclusions: Ours results not only describe some unknown aspects of G. diazotrophicus physiology, but open up the possibility of developing a technology of levans production by this organism using culture media with sucrose (or some cheaper substitute, like molasses) and without the addition of any N-source because of its ability of fixing atmospheric N2.

Calcium binding to S. mutans grown in the presence or absence of sucrose

Sucrose is the most cariogenic dietary carbohydrate because it is a substrate for insoluble extracellular polysaccharide (IEPS) production in dental biofilms, which can proportionally decrease bacterial density and, consequently, the number of biofilm calcium (Ca) binding sites. Ca bound to bacterial cell walls can be released into the biofilm fluid during a cariogenic challenge, reducing the driving force for mineral dissolution provoked by the pH drop. Thus, we investigated the effect of an IEPS-rich extracellular matrix on bacterial Ca binding after treatment with Ca solutions. Streptococcus mutans Ingbritt 1600 was cultivated in culture broths supplemented with 1.0% sucrose or 0.5% glucose + 0.5% fructose. The IEPS concentration in bacterial pellets was determined after alkaline extraction. Bacterial pellets were treated with 1 mM or 10 mM Ca++ solutions at 37ºC for 10 to 60 min. Ca binding to bacterial pellets, determined after acid extraction using the Arsenazo III reagent, was fast and concentration dependent. Although the IEPS concentration was approximately ten times higher in bacterial pellets cultivated in sucrose as compared to its monossaccharides, bound Ca concentration after Ca treatment was similar in both conditions. These results suggest that IEPS may not influence the amount of Ca bound to reservoirs of dental biofilms.

Cold-induced sweetening development in Indian potato (Solanum tuberosum L.) varieties.

Developing cold sweetening resistant processing varieties is one of the frontal areas of research all over the world. In India, first potato processing variety was released in the year 1998 and till 2005 three varieties have been developed. But, there is no information available regarding sugar accumulation response of Indian varieties to low temperature storage. Therefore, it is imperative to generate basic information on cold sweetening development in Indian processing varieties for the use of potato breeders. Development of cold-induced sweetening and its relation to phenolic content of the tuber was studied in three Indian potato varieties viz., Kufri Chipsona-1, Kufri Chipsona-3 and Kufri Jyoti. The reducing sugars decreased in initial phase of storage, followed by continuous increase to unacceptably higher levels after around two weeks of storage. The increase in reducing sugar contents took place subsequent to increase in sucrose content. The changes in phenol content were not in a fixed trend. The degree or number of folds increase in reducing sugar content was relatively less in Kufri Jyoti which contained highest phenol content among the three varieties investigated. It is suggested that development of processing varieties with higher anti-oxidant content and lower invertase activity may provide better cold-induced sweetening resistance.

Biotransformation of sucrose into 5-hydroxy-2-hydroxymethyl-γ-pirone by Aspergillus flavus

The sucrose hydrolysis and the preference of consumption of glucose instead of fructose were investigated for the production of 5-hydroxy-2-hydroxymethyl-γ-pyrone (HHMP) in the presence of Aspergillus flavus IOC 3974 cultivated in liquid Czapeck medium. Standardized 0.5g of pellets were transferred as inoculum into twelve conical flasks of 250 ml containing 100 ml of medium with different sucrose concentration, which was kept at 120 rpm and 28"C for 16 days without pH adjustment. Aliquots of 500μl of the broth culture were withdrawn at 24 h intervals and analyzed. The major yield of HHMP was 26g l-1 in 120g l-1 of sucrose. At these conditions, A. flavus produced an invertase capable of hydrolyzing 65 percent of total sucrose concentration in 24h, and an isomerase capable of converting fructose into glucose. In this work, it focused the preference for glucose and, then, of fructose by A. flavus and the strategy used to produce HHMP.

Foram investigadas a hidrólise da sacarose e a preferência pela glicose frente à frutose no processo de produção do 5-hidroxi-2-hidroximetil-γ-pirona (HHMP) na presença de Aspergillus flavus IOC 3974 cultivado em meio líquido Czapeck. Quantidades de 0,5g de pelletes foram utilizadas como inóculo. Doze frascos cônicos de 250 ml contendo 100 ml de meio de culturacom diferentes concentrações de sacarose foram utilizados.Os microrganismos foram cultivados a 120 rpm e 28"C por 16 dias sem ajuste do pH. O maior rendimento do HHMP foi 26g l-1em 120g l-1de sacarose. Nestas condições, A. flavus, foi capaz de produzir uma invertase possibilitando a hidrólise de 65 por cento da concentração total de sacarose em 24 horas, conjuntamente com a produção de uma isomerase que foi capaz de converter a frutose em glicose. Este trabalho está focalizado preferencialmente no consumo da glicose frente à frutose por A. flavus e na estratégia de produção do HHMP.

S. mutans biofilm model to evaluate antimicrobial substances and enamel demineralization

The aim of this study was to validate a model of S. mutans biofilm formation, which simulated 'feast-famine' episodes of exposure to sucrose that occur in the oral cavity, showed dose-response susceptibility to antimicrobials and allowed the evaluation of substances with anticaries potential. S. mutans UA159 biofilms were grown for 5 days on bovine enamel slabs at 37°C, 10 percent CO2. To validate the model, the biofilms were treated 2x/day with chlorhexidine digluconate (CHX) at 0.012, 0.024 and 0.12 percent (concentration with recognized anti-plaque effect) and 0.05 percent NaF (concentration with recognized anti-caries effect). CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p < 0.05). Whereas, 0.05 percent NaF did not show antimicrobial effect but had similar effect to that of 0.12 percent CHX decreasing enamel demineralization (p < 0.05). The model developed has potential to evaluate the effect of substances on biofilm growth and on enamel demineralization.

Virulence Characteristics of Sucrose-fermenting Vibrio vulnificus Strains / 대한진단검사의학회지

We identified 6 sucrose-fermenting Vibrio vulnificus strains and examined their virulence characteristics. They were all encapsulated, motile, capable of producing toxins and utilizing transferrin-bound iron, cytotoxic to cultured cells, and virulent enough to kill mice. They could be definitely identified only by genetic identification methods such as PCR, and not by conventional culture-based identification methods such as API 20E (bioMerieux, France). These results indicate that it is essential to adopt genetic approaches as early as possible in order to avoid misdiagnosis of such strains, especially in clinical situations.

Ocorrência e biossíntese de frutooligossacarídeos em banana / Occurrence and biosynthesis of fructooligosaccharides in banana

A banana tem sido comumente indicada como uma boa fonte de frutooligossacarídeos (FOS), que são considerados componentes funcionais de alimentos. Contudo, diferenças significantes em suas quantidades têm sido referidas na literatura. Portanto, uma parte do trabalho foi destinada à identificação e quantificação de FOS durante o amadurecimento de cultivares de bananas pertencentes aos grupos genômicos mais comumente cultivados no Brasil. Considerando as diferencas de cultivar, estágio do amadurecimento e metodologia usada para análise de FOS, os conteúdos dos acúcares foram analisados por cromatografia líquida de alta performance (HPAEC-PAD) e cromatografia a gás (CG-MS). Uma pesquisa inicial entre oito cultivares no estágio maduro, mostrou acúmulo de 1-cestose, primeiro membro da série de FOS, em todas elas (quantidades entre 297 e 1600 ´MUg/g M. S´). A nistose, o segundo membro, foi detectado somente no cultivar Prata. Com bases nestes dados, foram escolhidas cinco cultivares, para que fossem analisadas durantes todo o amadurecimento. Os resultados mostraram uma forte correlação entre a síntese de 1-cestose e um nível específico de sacarose (~200mg/g M.S)...

Sacarose como veículo de suplementação dietética de ácido fólico em camundongos prenhes / Saccharose as a vehicle for the supplementation of folic acid in pregnant mice

INTRODUÇÃO: A ingestão adequada de folato é essencial durante a embriogênese, e sua deficiência está associada à ocorrência de defeitos no fechamento do tubo neural. OBJETIVO: Determinar se a sacarose é um bom veículo para a suplementação de folato em camundongos. MATERIAL E MÉTODOS: Quarenta camundongos Swiss fêmeas foram divididos nos grupos: C: ração comercial + água ad libitum; DS: ração balanceada isenta de folato + folato adicionado à sacarose diluída na água por 14 dias; D/DS: ração balanceada isenta de folato + água com sacarose sem folato por 14 dias seguida de ração balanceada isenta de folato + folato adicionado à sacarose diluída na água por mais 14 dias; D: ração balanceada isenta de folato + água com sacarose sem folato por 14 dias. Os animais de todos os grupos experimentais receberam ração balanceada isenta de folato + folato adicionado à sacarose diluída na água durante os três dias do acasalamento e nos 15 dias restantes até o sacrifício. RESULTADOS: Os animais dos grupos D e D/DS apresentaram alopecia, palidez ocular e adinamia enquanto consumiam água com sacarose sem folato, sinais que foram revertidos quando receberam folato adicionado à sacarose diluída na água. Não houve diferença entre os grupos em relação a prenhez, implantes, fetos vivos, reabsorção, morte fetal tardia, nível sérico de folato e contagem de hemácias ao final do experimento, não tendo sido observadas anomalias congênitas em nenhum dos grupos. CONCLUSÃO: A sacarose é um meio adequado para a suplementação de folato na dieta.

Adequate folate intake is essential during embryogenesis and its deficiency is associated with neural tube defects. OBJECTIVE: To investigate if saccharose is a good vehicle for the supplementation of folate in mice. MATERIAL AND METHODS: 40 Swiss female mice were allocated into the following groups: C (commercial mouse food + ad libitum water); DS (folate-free balanced diet + saccharose with folate diluted in water for 14 days); D/DS (folate-free balanced diet + folate-free saccharose diluted in water for 14 days, followed by folate-free balanced diet + saccharose with folate diluted in water for 14 days); D (folate-free balanced diet + folate-free saccharose diluted in water for 14 days). Mice from all experimental groups received folate-free balanced diet + saccharose with folate diluted in water during their three-day mating period and thereafter 15 days until animals were put down. RESULTS: Mice from groups D and D/DS showed alopecia, pale eyes and adynamia while on folate-free saccharose water regimen. These symptoms disappeared after the introduction of saccharose with folate diluted in water. No statistical difference was noted among groups as to pregnancy, number of implants, live fetuses, reabsorption, late fetal death, serum folate levels and red blood cells count and no congenital abnormalities were identified in any groups by the end of the experiment. CONCLUSION: Saccharose is a suitable vehicle for the dietary supplementation of folate.

The effect of nitrogen and potassium fertilizers on growth parameters and carbohydrate contents of sweet sorghum cultivars.

Sweet sorghum is tolerant to high temperature and drought and can be considered as an alternative crop to sugar beet and maize in Iran. In this study, the effects of nitrogen and potassium fertilizers on growth parameters including stem height, stem diameter, stem fresh weight, total fresh weight; carbohydrate contents including total sugar, brix value, sucrose content and purify; and juice extract of two sweet sorghum cultivars were determined. Three rates of N-fertilizer (0, 90, 180 kg urea ha(-1)) and two rates of K fertilizer (0 and 50 kg potassium sulfate ha(-1)) assigned as main plots and two sweet sorghum cultivars (Rio and Keller) as subplots. Growth parameters at soft dough and physiological maturity stages and carbohydrate contents at physiological maturity stage were determined. Results showed that application of 180 kg urea ha(-1) as compared to control at physiological maturity significantly (p < 0.01) increased stem height (12.65%), stem fresh weight (24.57%), total fresh weight (78.22%), total sugar (39.25%), sucrose content (9%) and juice extract (34.96%). Application of 50 kg potassium sulfate ha(-1) increased (p < 0.05) stem fresh weight (24.33%), total fresh weight (25.44%), total sugar (10.50%), and juice extract (9%) at physiological maturity. The highest growth parameters, carbohydrate contents and juice extract were obtained with the application of 180 kg urea ha(-1) and 50 kg potassium sulfate ha(-1) using cultivar (cv) Keller. The best results were taken with the application of both fertilizers.

Effect of water deficit on carbohydrate status and enzymes of carbohydrate metabolism in seedlings of wheat cultivars.

The effect of water deficit on carbohydrate status and enzymes of carbohydrate metabolism (alpha and beta amylases, sucrose phosphate synthase, sucrose synthase, acid and alkaline invertases) in wheat (Triticum aestivum L.) was investigated in the seedlings of drought-sensitive (PBW 343) and drought-tolerant (C 306) cultivars. The water deficit was induced by adding 6% mannitol (water potential -0.815 Mpa) in the growth medium. The water deficit reduced starch content in the shoots of tolerant seedlings as compared to the sensitive ones, but increased sucrose content in the shoots and roots of tolerant seedlings, indicating their protective role during stress conditions. It also decreased the alpha-amylase activity in the endosperm of seedlings of both the cultivars, but increased alpha and beta amylase activities in the shoots of tolerant ones. Sucrose phosphate synthase (SPS) activity showed a significant increase at 6 days of seedling growth (DSG) in the shoots of stressed seedlings of tolerant cultivar. However, SPS activity in the roots of stressed seedlings of sensitive cultivar was very low at 4 DSG and appeared significantly only at day 6. Sucrose synthase (SS) activity was lower in the shoots and roots of stressed seedlings of tolerant cultivar than sensitive ones at early stage of seedling growth. Higher acid invertase activity in the shoots of seedlings of tolerant cultivar appeared to be a unique characteristic of this cultivar for stress tolerance. Alkaline invertase activity, although affected under water deficit conditions, but was too low as compared to acid invertase activity to cause any significant affect on sucrose hydrolysis. In conclusion, higher sucrose content with high SPS and low acid invertase and SS activities in the roots under water deficit conditions could be responsible for drought tolerance of C 306.

Genotypic diversity of S. mutans in dental biofilm formed in situ under sugar stress exposure

In situ dental biofilm composition under sugar exposure is well known, but sugar effect on the genotypic diversity of S. mutans in dental biofilm has not been explored. This study evaluated S. mutans genotypic diversity in dental biofilm formed in situ under frequent exposure to sucrose and its monosaccharide constituents (glucose and fructose). Saliva of 7 volunteers was collected for isolation of S. mutans and the same volunteers wore intraoral palatal appliances, containing enamel slabs, which were submitted to the following treatments: distilled and deionized water (negative control), 10 percent glucose + 10 percent fructose (fermentable carbohydrates) solution or 20 percent sucrose (fermentable and EPS inductor) solution, 8x/day. After 3, 7 and 14 days, the biofilms were colleted and S. mutans colonies were isolated. Arbitrarily primed polymerase chain reaction (AP-PCR) of S. mutans showed that salivary genotypes were also detected in almost all biofilm samples, independently of the treatment, and seemed to reflect those genotypes present at higher proportion in biofilms. In addition to the salivary genotypes, others were found in biofilms but in lower proportions and were distinct among treatment. The data suggest that the in situ model seems to be useful to evaluate genotypic diversity of S. mutans, but, under the tested conditions, it was not possible to clearly show that specific genotypes were selected in the biofilm due to the stress induced by sucrose metabolism or simple fermentation of its monosaccharides.

A composição do biofilme dental in situ exposto a açúcares é bem conhecida, mas o efeito dos açúcares na diversidade genotípica de S. mutans no biofilme dental ainda não foi explorada. Este estudo avaliou a diversidade genotípica de S. mutans no biofilme dental formado in situ sob frequente exposição à sacarose e seus monossacarídeos constituintes (glicose e frutose). Primeiramente, saliva de voluntários foi coletada para isolamento de S. mutans e os mesmos voluntários usaram um dispositivo intraoral palatino, contendo blocos de esmalte, que foram submetidos 8x/dia aos seguintes tratamentos: água destilada e deionizada (controle negativo), solução de glicose 10 por cento + frutose 10 por cento (carboidratos fermentáveis) e solução de sacarose 20 por cento (fermentável e indutor de PEC). Após 3, 7 e 14 dias, os biofilmes foram coletados e colônias de S. mutans foram isoladas. A técnica de reação em cadeia de polimerase usando primers arbitrários (AP-PCR) demonstrou que o genótipo salivar foi detectado em quase todas as amostras de biofilme, independente do tratamento, e parece refletir aqueles genótipos presentes em maiores proporções no biofilme. Além do genótipo salivar, outros foram encontrados nos biofilmes, mas em uma menor proporção e foram distintos entre os tratamentos. Os dados sugerem que o modelo in situ é útil para a avaliação da diversidade genotípica de S. mutans. Porém, nas condições do presente estudo, não foi possível demonstrar que genótipos específicos foram detectados no biofilme devido ao estresse induzido pelo metabolismo da sacarose ou fermentação de seus monossacarídeos.