Effects of abscisic acid, ethylene and sugars on the mobilization of storage proteins and carbohydrates in seeds of the tropical tree Sesbania virgata (Leguminosae)

Endospermic legumes are abundant in tropical forests and their establishment is closely related to the mobilization of cell-wall storage polysaccharides. Endosperm cells also store large numbers of protein bodies that play an important role as a nitrogen reserve in this seed. In this work, a systems approach was adopted to evaluate some of the changes in carbohydrates and hormones during the development of seedlings of the rain forest tree Sesbania virgata during the period of establishment. Seeds imbibed abscisic acid (ABA), glucose and sucrose in an atmosphere of ethylene, and the effects of these compounds on the protein contents, alpha-galactosidase activity and endogenous production of ABA and ethylene by the seeds were observed. The presence of exogenous ABA retarded the degradation of storage protein in the endosperm and decreased alpha-galactosidase activity in the same tissue during galactomannan degradation, suggesting that ABA represses enzyme action. On the other hand, exogenous ethylene increased alpha-galactosidase activity in both the endosperm and testa during galactomannan degradation, suggesting an inducing effect of this hormone on the hydrolytic enzymes. Furthermore, the detection of endogenous ABA and ethylene production during the period of storage mobilization and the changes observed in the production of these endogenous hormones in the presence of glucose and sucrose, suggested a correlation between the signalling pathway of these hormones and the sugars. These findings suggest that ABA, ethylene and sugars play a role in the control of the hydrolytic enzyme activities in seeds of S. virgata, controlling the process of storage degradation. This is thought to ensure a balanced flow of the carbon and nitrogen for seedling development.

Nutritional information of meals supplied by companies, participating in the workers` meal program in Sao Paulo, Brazil

Objective. To compare the nutritional value of meals provided by companies participating in the Workers` Meal Program in the city of Sao Paulo, Brazil, to the nutritional recommendations and guidelines established by the Ministry of Health for the Brazilian population. Methods. The 72 companies studied were grouped according to economic sector (industrial, services, or commerce), size (micro, small, medium, or large), meal preparation modality (prepared on-site by the company itself, on-site by a hired caterer, or off-site by a hired caterer), and supervision by a dietitian (yes or no). The per capita amount of food was determined based on the lunch, dinner, and supper menus for three days. The nutritional value of the meals was defined by the amount of calories, carbohydrates, protein, total fat, polyunsaturated fat, saturated fat, trans fat, sugars, cholesterol, and fruits and vegetables. Results. Most of the menus were deficient in the number of fruits and vegetables (63.9%) and amount of polyunsaturated fat (83.3%), but high in total fat (47.2%) and cholesterol (62.5%). Group 2, composed of mostly medium and large companies, supervised by a dietician, belonging to the industrial and/or service sectors, and using a hired caterer, on averaged served meals with higher calorie content (P < 0.001), higher percentage of polyunsaturated fat (P < 0.001), more cholesterol (P = 0.015), and more fruits and vegetables (P < 0.001) than Group 1, which was composed of micro and small companies from the commercial sector, that prepare the meals themselves on-site, and are not supervised by a dietitian. Regarding the nutrition guidelines set for the Brazilian population, Group 2 meals were better in terms of fruit and vegetable servings (P < 0.001). Group I meals were better in terms of cholesterol content (P = 0.05). Conclusions. More specific action is required targeting company officers and managers in charge of food and nutrition services, especially in companies without dietitian supervision.

Propagation, growth, and carbohydrates of Dendrobium Second Love (Orchidaceae) in vitro as affected by sucrose, light, and dark

In general, plant material grown in vitro has low photosynthetic ability to achieve positive carbon balances. Therefore, a continuous supply of carbohydrates from the culture medium is required, and sucrose has been the most commonly used carbon source. In this paper, we investigate the effects of different sucrose concentrations and the presence and absence of light on the endogenous levels of soluble carbohydrates and starch as well as on the proliferation and growth of Dendrobium Second Love (Orchidaceae) in vitro. The possibility of using etiolated stem segments as a means for micropropagating this hybrid was also verified. The results obtained indicated that the presence and absence of light and the sucrose concentrations used influenced the amounts of soluble carbohydrates and starch and the proliferation of D. Second Love shoots and roots. An increase in sucrose concentration caused a progressive increase in the amounts of total carbohydrates and starch. Under both light conditions, sucrose was the main sugar found in the shoots followed by glucose and fructose. The addition of sucrose to the culture medium up to 2% and 4% was advantageous to the number of shoots produced per explant and the root longitudinal growth in the presence and absence of light, respectively. Shoot and root dry matter and the number of roots formed per explant increased as sucrose concentration was raised up to 6% in both light treatments. The use of dark-grown shoot segments proved to be a useful and reliable alternative for the micropropagation of this hybrid.

Dynamics of biochemical and morphophysiological changes during zygotic embryogenesis in Acca sellowiana (Berg.) Burr.

Acca sellowiana (Berg.) Burr. is a native Myrtaceae from southern Brazil and Uruguay, now the subject of a domestication and breeding program. Biotechnological tools have been used to assist in this program. The establishment of a reliable protocol of somatic embryogenesis has been pursued, with a view to capturing and fixing genetic gains. The rationale behind this work relies on the fact that deepening comprehension of the general metabolism of zygotic embryogenesis may certainly improve the protocol for somatic embryogenesis. Thus, in the present work we studied the accumulation of protein, total sugars, starch, amino acids, polyamines (PAs), IAA and ABA, in different stages of A. sellowiana zygotic embryogenesis. Starch is the predominant storage compound during zygotic embryo development. Increased synthesis of amino acids in the cotyledonary stage, mainly of asparagine, was observed throughout development. Total free PAs showed increased synthesis, whereas total conjugated PAs were mainly observed in the early developmental stages. IAA decreased and ABA increased with the progression from early to late embryogenesis. Besides providing basic information on the morphophysiological and biochemical changes of zygotic embryogenesis, the results here obtained may provide adequate strategies towards the modulation of somatic embryogenesis in this species as well as in other woody angiosperms.

The role of carbohydrates in seed germination and seedling establishment of Himatanthus sucuuba, an Amazonian tree with populations adapted to flooded and non-flooded conditions

Background and Aims In the Amazonian floodplains plants withstand annual periods of flooding which can last 7 months. Under these conditions seedlings remain submerged in the dark for long periods since light penetration in the water is limited. Himatanthus sucuuba is a tree species found in the `varzea` (VZ) floodplains and adjacent non-flooded `terra-firme` (TF) forests. Biochemical traits which enhance flood tolerance and colonization success of H. sucuuba in periodically flooded environments were investigated. Methods Storage carbohydrates of seeds of VZ and TF populations were extracted and analysed by HPAEC/PAD. Starch was analysed by enzyme (glucoamylase) degradation followed by quantification of glucose oxidase. Carbohydrate composition of roots of VZ and TF seedlings was studied after experimental exposure to a 15-d period of submersion in light versus darkness. Key Results The endosperm contains a large proportion of the seed reserves, raffinose being the main nonstructural carbohydrate. Around 93% of the cell wall storage polysaccharides (percentage dry weight basis) in the endosperm of VZ seeds was composed of mannose, while soluble sugars accounted for 2.5%. In contrast, 74% of the endosperm in TF seeds was composed of galactomannans, while 22% of the endosperm was soluble sugars. This suggested a larger carbohydrate allocation to germination in TF populations whereas VZ populations allocate comparatively more to carbohydrates mobilized during seedling development. The concentration of root non-structural carbohydrates in non-flooded seedlings strongly decreased after a 15-d period of darkness, whereas flooded seedlings were less affected. These effects were more pronounced in TF seedlings, which showed significantly lower root non-structural carbohydrate concentrations. Conclusions There seem to be metabolic adjustments in VZ but not TF seedlings that lead to adaptation to the combined stresses of darkness and flooding. This seems to be important for the survival of the species in these contrasting environments, leading these populations to different directions during evolution.

Changes in soluble carbohydrates and starch amounts during somatic and zygotic embryogenesis of Acca sellowiana (Myrtaceae)

Comparative analysis of zygotic and somatic embryogenesis of Acca sellowiana showed higher amounts of sucrose, fructose, raffinose, and myo-inositol in zygotic embryos at different developmental stages than in corresponding somatic ones. These differences were mostly constant. In general, glucose levels were significantly lower than the other soluble carbohydrates analyzed, showing minor variation in each embryo stage. Despite the presence of sucrose in the culture medium, its levels conspicuously diminished in somatic embryos compared with the zygotic ones. Raffinose enhanced parallel to embryo development, regardless of its zygotic or somatic origin. Analysis of the soluble carbohydrate composition of mature zygotic cotyledon used as explant pointed out fructose, glucose, myo-inositol, sucrose, and raffinose as the most important. Similar composition was also found in the corresponding somatic cotyledon. Total soluble carbohydrates varied inversely, decreasing in zygotic embryos and increasing in somatic embryos until the 24th d, at which time they increased rapidly about sixfold in zygotic embryos until the 27th d, a period coinciding with the zygotic proembryos formation. Such condition seems to reflect directly the variation of endogenous sucrose level, mainly because glucose and fructose diminished continuously during this time period. This means that, in terms of soluble sugars, zygotic embryo formation occurred under a situation represented by high sucrose amounts, simultaneously with low fructose and glucose levels, while in contrast, somatic embryo formation took place under an endogenous sugar status characterized by a substantial fructose enhancement. Starch levels increased continuously in zygotic embryos and decreased in somatic ones, the reverse to what was found in fructose variation. Starch accumulation was significantly higher in somatic torpedo and cotyledonary embryos than in the corresponding zygotic ones.

Transporters involved in glucose and water absorption in the Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) anterior midgut

Little is known about insect intestinal sugar absorption, in spite of the recent findings, and even less has been published regarding water absorption. The aim of this study was to shed light on putative transporters of water and glucose in the insect midgut Glucose and water absorptions by the anterior ventriculus of Dysdercus peruvianus midgut were determined by feeding the insects with a glucose and a non-absorbable dye solution, followed by periodical dissection of insects and analysis of ventricular contents. Glucose absorption decreases glucose/dye ratios and water absorption increases dye concentrations. Water and glucose transports are activated (water 50%, glucose 33%) by 50 mM K(2)SO(4) and are inhibited (water 46%, glucose 82%) by 0.2 mM phloretin, the inhibitor of the facilitative hexose transporter (GLUT) or are inhibited (water 45%, glucose 35%) by 0.1 mM phlorizin, the inhibitor of the Na(+)-glucose cotransporter (SGLT). The results also showed that the putative SGLT transports about two times more water relative to glucose than the putative GLUT. These results mean that D. peruvianus uses a GLUT-like transporter and an SGLT-like transporter (with K(+) instead of Na(+)) to absorb dietary glucose and water. A cDNA library from D. peruvianus midgut was screened and we found one sequence homologous to GLUT1, named DpGLUT, and another to a sodium/solute symporter, named DpSGLT. Semi-quantitative RT-PCR studies revealed that DpGLUT and DpSGLTs mRNA were expressed in the anterior midgut, where glucose and water are absorbed, but not in fat body, salivary gland and Malpighian tubules. This is the first report showing the involvement of putative GLUT and SGLT in both water and glucose midgut absorption in insects. (C) 2010 Elsevier Inc. All rights reserved.

PHB Biosynthesis in Catabolite Repression Mutant of Burkholderia sacchari

Due to the effect of catabolite repression, sugar mixtures cannot be metabolized in a rapid and efficient way implicating in lower productivity in bioprocesses using lignocellulosic hydrolysates. In gram-negative bacteria, this mechanism is mediated by the phosphotransferase system (PTS), which concomitantly internalizes and phosphorylates sugars. In this study, we isolated a UV mutant of Burkholderia sacchari, called LFM828, which transports hexoses and pentoses by a non-PTS uptake system. This mutant presented released glucose catabolite repression over the pentoses. In mixtures of glucose, xylose, and arabinose, specific growth rates and the specific sugar consumption rates were, respectively, 10 and 23% higher in LFM828, resulting in a reduced time to exhaust all sugars in the medium. However, in polyhydroxybutyrate (PHB) biosynthesis experiments it was necessary the supplementation of yeast extract to maintain higher values of growth rate and sugar consumption rate. The deficient growth in mineral medium was partially recovered by replacing the ammonium nitrogen source by glutamate. It was demonstrated that the ammonium metabolism is not defective in LFM828, differently from ammonium, glutamate can also be used as carbon and energy allowing an improvement on the carbohydrates utilization for PHB production in LFM828. In contrast, higher rates of ammonia consumption and CO(2) production in LFM828 indicate altered fluxes through the central metabolism in LFM828 and the parental. In conclusion, PTS plays an important role in cell physiology and the elimination of its components has a significant impact on catabolite repression, carbon flux distribution, and PHB biosynthesis in B. sacchari.

Isolation of a lectin and a galactoxyloglucan from Mucuna sloanei seeds

A lectin and a galactoxyloglucan were characterized from Mucuna sloanei seed cotyledons. The galactoxyloglucan, isolated by water extraction and ethanol precipitation, had Glc:Xyl:Gal proportions in a molar ratio of 1.8:1.7:1.0 and a molar mass (M(w)) of 1.6 x 10(6) g mol(-1). The lectin (sloanin), isolated from the same seed by affinity chromatography on cross-linked Adenanthera pavonina galactomannan, gave two protein bands by SDS-PAGE (36 and 34 kDa) and one peak by gel filtration (63.6 kDa). Its N-terminal sequence indicated similar to 69% identity with soybean agglutinin to leguminous lectins. Circular dichroism (CD) spectra established that sloanin predominantly contains beta-sheet structures. Sloanin has similar to 5.5% carbohydrate and displayed hemagglutinating activity against rabbit and enzyme treated human erythrocytes, inhibited only by D-Gal containing sugars. The interaction between sloanin and storage cell-wall galactoxyloglucan was tested by affinity chromatography and fluorescence spectroscopy. (C) 2009 Elsevier Ltd. All rights reserved.

The reduction of Cu(II)/neocuproine complexes by some polyphenols: Total polyphenols determination in wine samples

A new method is presented for spectrophotometric determination of total polyphenols content in wine. The procedure is a modified CUPRAC method based on the reduction of Cu(II), in hydroethanolic medium (pH 7.0) in the presence of neocuproine (2,9-dimethyl-1,10-phenanthroline), by polyphenols, yielding a Cu(I) complexes with maximum absorption peak at 450 nm. The absorbance values are linear (r = 0.998, n = 6) with tannic acid concentrations from 0.4 to 3.6 mu mol L(-1). The limit of detection obtained was 0.41 mu mol L(-1) and relative standard deviation 1.2% (1 mu mol L(-1); n = 8). Recoveries between 80% and 110% (mean value of 95%) were calculated for total polyphenols determination in 14 commercials and 2 synthetic wine samples (with and without sulphite). The proposed procedure is about 1.5 more sensitive than the official Folin-Ciocalteu method. The sensitivities of both methods were compared by the analytical responses of several polyphenols tested in each method. (C) 2010 Elsevier Ltd. All rights reserved.

Cassava bagasse cellulose nanofibrils reinforced thermoplastic cassava starch

Cellulose cassava bagasse nanofibrils (CBN) were directly extracted from a by-product of the cassava starch (CS) industry, viz. the cassava bagasse (CB), The morphological structure of the ensuing nanoparticles was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), presence of other components such as sugars by high performance liquid chromatography (HPLC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) experiments. The resulting nanofibrils display a relatively low crystallinity and were found to be around 2-11 nm thick and 360-1700 nm long. These nanofibrils were used as reinforcing nanoparticles in a thermoplastic cassava starch matrix plasticized using either glycerol or a mixture of glycerol/sorbitol (1:1) as plasticizer. Nanocomposite films were prepared by a melting process. The reinforcing effect of the filler evaluated by dynamical mechanical tests (DMA) and tensile tests was found to depend on the nature of the plasticizer employed. Thus, for the glycerol-plasticized matrix-based composites, it was limited especially due to additional plasticization by sugars originating from starch hydrolysis during the acid extraction. This effect was evidenced by the reduction of glass vitreous temperature of starch after the incorporation of nanofibrils in TPSG and by the increase of elongation at break in tensile test. On the other hand, for glycerol/sorbitol plasticized nanocomposites the transcrystallization of amylopectin in nanofibrils surface hindered good performances of CBN as reinforcing agent for thermoplastic cassava starch. The incorporation of cassava bagasse cellulose nanofibrils in the thermoplastic starch matrices has resulted in a decrease of its hydrophilic character especially for glycerol plasticized sample. (C) 2009 Elsevier Ltd. All rights reserved.