Low temperature induced changes in activity and protein levels of the enzymes associated to conversion of starch to sucrose in banana fruit

Storage at low temperature is the most frequently used method to extend the shelf life of banana fruit, and is fundamental for extended storage and transport over long distances. However, storage and transport conditions must be carefully controlled because of the high susceptibility of many commercial cultivars to chilling injury. The physiological behavior of bananas at low temperatures has been studied to identify possible mechanisms of resistance to chilling injury. The aim of this work was to evaluate differences in the starch-to-sucrose metabolism of a less tolerant and susceptible (Musa acuminata, AAA cv. Nanicao) and a more tolerant (M. acuminata x Musa balbusiana, AAB, cv. Prata) banana cultivar to chilling injury. Fruits of these cultivars were stored in chambers at 13 degrees C for 15 d, at which point they were transferred to 19 degrees C, where they were left until complete ripening. The low temperature induced significant changes in the metabolism of starch and sucrose in comparison to fruit ripened only at 19 degrees C. The sucrose accumulation was slightly higher in cv. Prata, and different patterns of starch degradation, sucrose synthesis, activity and protein levels of the alpha-and beta-amylases, starch phosphorylase, sucrose synthase and sucrose phosphate synthase were detected between the cultivars. Our results suggest that starch-to-sucrose metabolism is likely part of the mechanism for cold acclimation in banana fruit, and the cultivar-dependent differences contribute to their ability to tolerate cold temperatures. (C) 2011 Elsevier B.V. All rights reserved.

Phenolics and Antioxidant Properties of Fruit Pulp and Cell Wall Fractions of Postharvest Banana (Musa acuminata Juss.) Cultivars

Banana fruits are important foods, but there have been very few studies evaluating the phenolics associated with their cell walls. In the present study, (+) catechin, gallocatechin, and (-) epicatechin, as well as condensed tannins, were detected in the soluble extract of the fruit pulp; neither soluble anthocyanidins nor anthocyanins were present. In the soluble cell wall fraction, two hydroxycinnamic acid derivatives were predominant, whereas in the insoluble cell wall fraction, the anthocyanidin delphinidin, which is reported in banana cell walls for the first time, was predominant. Cell wall fractions showed remarkable antioxidant capacity, especially after acid and enzymatic hydrolysis, which was correlated with the total phenolic content released after the hydrolysis of the water-insoluble polymer, but not for the posthydrolysis water-soluble polymer. The acid hydrolysis released various monosaccharides, whereas enzymatic hydrolysis released one peak of oligosaccharides. These results indicate that banana cell walls could be a suitable source of natural antioxidants and that they could be bioaccessible in the human gut.

Vitamin D Receptor and Calcium-Sensing Receptor Gene Polymorphisms in Hypercalciuric Stone-Forming Patients

Background/Aim: Some studies have identified an association of kidney stone formation with vitamin D receptor (VDR) or calcium-sensing receptor (CaSR) polymorphisms. We aimed to evaluate the association between these polymorphisms with urinary calcium excretion (uCa) in calcium-stone-forming patients. Methods: VDR polymorphism, detected by BsmI digestion, and 3 CaSR polymorphisms (G/T at codon 986, G/A at codon 990 and C/G at codon 1011), detected by direct sequencing, were evaluated in 100 hypercalciuric (HCa) and 101 normocalciuric (NCa) calcium-stone-forming patients. Results: The total allelic frequency of VDR polymorphism was: 16% BB, 49% Bb and 35% bb. The prevalence of bb genotype was significantly higher in the HCa when compared to the NCa group (43 vs. 27%). With respect to CaSR polymorphisms, 986S, 990G and 1011E variant alleles were detected, respectively, in 5, 4 and 3% of the whole sample and 5 CaSR haplotypes were identified: 94% ARQ (wildtype), 3% SRQ, 1.5% AGQ, 1.0% ARE and 0.5% AGE. No statistical differences have been observed between NCa and HCa with respect to these CaSR haplotypes. Conclusions: The present study suggested that bb homozygous for VDR polymorphism was overrepresented in hypercalciuric stone formers. Urinary calcium excretion was not associated with CaSR polymorphism in the present sample. Copyright (C) 2009 S. Karger AG, Basel

Molecular cloning and characterization of a ripening-induced polygalacturonase related to papaya fruit softening

Pulp softening is one of the most remarkable changes during ripening of papaya (Carica papaya) fruit and it is a major cause for post-harvest losses. Although cell wall catabolism has a major influence on papaya fruit, quality information on the gene products involved in this process is limited. A full-length polygalacturonase cDNA (cpPG) was isolated from papaya pulp and used to study gene expression and enzyme activity during normal and ethylene-induced ripening and after exposure of the fruit to 1-MCP. Northern-blot analysis demonstrated that cpPG transcription was strongly induced during ripening and was highly ethylene-dependent. The accumulation of cpPG transcript was paralleled by enzyme activity, and inversely correlated to the pulp firmness. Preliminary in silica analysis of the cpPG genomic sequence revealed the occurrence of putative regulatory motifs in the promoter region that may help to explain the effects of plant hormones and non-abiotic stresses on papaya fruit firmness. This newly isolated cpPG is an important candidate for functional characterization and manipulation to control the process of pulp softening during papaya ripening. (C) 2009 Elsevier Masson SAS. All rights reserved.

Benzylglucosinolate, Benzylisothiocyanate, and Myrosinase Activity in Papaya Fruit during Development and Ripening

Papaya is a climacteric fruit that has high amounts of benzylglucosinolates (BG) and benzylisothiocyanates (BITC), but information regarding levels of BG or BITC during fruit development and ripening is limited. Because BG and BITC are compounds of importance from both a nutritional and a crop yield standpoint, the aim of this work was to access data on the distribution and changes of BG and BITC levels during fruit development and ripening. BG and BITC levels were quantified in peel, pulp, and seeds of papaya fruit. Volatile BITC was also verified in the internal cavity of the fruit during ripening. The influence of the ethylene in BG and BITC levels and mirosinase activity was tested by exposing mature green fruits to ethylene and 1-methylcyclopropene (1-MCP). The highest BG levels were detected in seeds, followed by the peel and pulp being decreased in all tissues during fruit development. Similarly, the levels of BITC were much higher in the seeds than the peel and pulp. The levels of BG for control and ethylene-treated fruit were very similar, increasing in the pulp and peel during late ripening but not changing significantly in seeds. On the other hand, fruit exposed to 1-MCP showed a decrease in BG amount in the pulp and accumulation in seed. The treatments did not result in clear differences regarding the amount of BITC in the pulp and peel of the fruit. According to the results, ethylene does not have a clear effect on BITC accumulation in ripening papaya fruit. The fact that BG levels in the pulp did not decrease during ripening, regardless of the treatment employed, and that papaya is consumed mainly as fresh fruit, speaks in favor of this fruit as a good dietary source for glucosinolate and isothiocyanates.

Ripening-associated changes in the amounts of starch and non-starch polysaccharides and their contributions to fruit softening in three banana cultivars

BACKGROUND: Fruit softening is generally attributed to cell wall degradation in the majority of fruits. However, unripe bananas contain a large amount of starch, and different banana cultivars vary in the amount of starch remaining in ripe fruits. Since studies on changes in pulp firmness carried outwith bananas are usually inconclusive, the cell wall carbohydrates and the levels of starch and soluble cell wall monosaccharides from the pulps of three banana cultivars were analysed at different ripening stages. RESULTS: Softening of Nanicao and Mysore bananas seemed to be more closely related to starch levels than to cell wall changes. For the plantain Terra, cell wall polysaccharide solubilisation and starch degradation appeared to be the main contributors. CONCLUSION: Banana softening is a consequence of starch degradation and the accumulation of soluble sugars in a cultivar-dependent manner. However, contributions from cell wall-related changes cannot be disregarded. (C) 2011 Society of Chemical Industry

Antimicrobial and Cytotoxic Activity of Fruit Extract from Syzygium cumini (L.) Skeels

The aim of the present study was to evaluate the antimicrobial and cytotoxic activity of the ethanolic extract of S. cumini according to the Clinical and Laboratory Standards Institute reference method (with modifications), determining the minimal inhibitory and lethal concentration. Activity against Gram-positive (Staphylococcus aureus and S. epidermidis), Gram-negative (Pseudomonas aeruginosa) and yeast of Candida sp and Cryptococcus neoformans was evaluated. The effects of the fruit extract were examined in hamster cells ovaries in concentrations ranging from 1250.0 a 4.9 mu g/ml, measuring the reduction of the tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium. The extract showed both bactericidal and fungicidal activity among the various microorganisms tested and the MIC ranging from 7.8 to 250 mu g/ml. The MIC, MBC and MFC should values that were similar for all the microorganisms. Cytotoxicity index of the dried extract corresponded to the concentration of 400 mu g/ml. The extract could potentially be used in topical antimicrobial products. Thus, the activity of extract was potent to bacteria and mainly to non-albicans species and C. neoformans.

Effects of calcium supplementation on body weight reduction in overweight calcium stone formers

A randomized, placebo-controlled trial was conducted in overweight calcium stone-forming (CSF) patients, to evaluate the effect of calcium supplementation associated with a calorie-restricted diet on body weight (BW) and fat reduction and its potential changes upon serum and urinary parameters. Fifteen patients were placed on a hypocaloric diet for 3 months, supplemented with either calcium carbonate (CaCO(3), n = 8) or placebo (n = 7), 500 mg bid. Blood and 24-h urine samples were collected and body composition was assessed at baseline and after the intervention. At the end of the study, final BW was significantly lower vs baseline in both CaCO(3) (74 +/- A 14 vs. 80 +/- A 14 kg, P = 0.01) and placebo groups (80 +/- A 10 vs. 87 +/- A 9 kg, P = 0.02) but the mean percentage of loss of body weight and body fat did not differ between CaCO(3) and placebo (7.0 +/- A 2.0 vs. 8.0 +/- A 3.0%, P = 0.40 and 13.0 +/- A 7.0 vs. 13.0 +/- A 10.0%; P = 0.81, respectively). After CaCO(3) or placebo, no significant differences versus baseline were observed for urinary parameters in both CaCO(3) and placebo, except for a higher mean urinary citrate in placebo group. These data suggest that increasing calcium intake by calcium carbonate supplementation did not contribute to a further reduction of BW and fat in overweight CSF patients submitted to a hypocaloric diet nor altered urinary lithogenic parameters.

Dietary fructose, fruits, fruit juices and glucose tolerance status in Japanese-Brazilians

Background and aims: Evidence suggests that fructose and sweetened beverages may be a risk factor for obesity and type 2 diabetes, but the role of sweetened fruit juices in glucose disturbances has been minimally explored. The aim of this study was to examine the association of total fructose, fresh fruit and sweetened fruit juice intake with glucose tolerance homeostasis in Japanese-Brazilians. Methods and results: A total of 475 men and 579 women aged >= 30 years were evaluated in a cross-sectional population-based survey with a standardized protocol including a 2-h oral glucose tolerance test (WHO criteria). Habitual food consumption was obtained using a validated food frequency questionnaire for Japanese-Brazitians. After adjustments for potential confounding variables, the odds ratio (OR; 95%Cl) for impaired glucose tolerance was 2.1 (1.0-4.5; P for trend = 0.05) for the highest as compared to the lowest tertile intake of total fructose and 2.3 (1.1-5.1; P for trend = 0.05) for the highest as compared to the lowest tertile intake of sweetened fruit juices. Conclusion: Our results showed that high intakes of dietary fructose and sweetened fruit juices, but not whole fresh fruits, were associated with impaired glucose tolerance among genetically susceptible individuals. (C) 2008 Elsevier B.V. All rights reserved.

Supercritical fluid extracts from the Brazilian cherry (Eugenia uniflora L.): Relationship between the extracted compounds and the characteristic flavour intensity of the fruit

Supercritical carbon dioxide (SC-CO(2)) extractions of Brazilian cherry (Eugenia uniflora L.) were carried out under varied conditions of pressure and temperature, according to a central composite 2(2) experimental design, in order to produce flavour-rich extracts. The composition of the extracts was evaluated by gas chromatography coupled with mass spectrometry (GC/MS). The abundance of the extracted compounds was then related to sensory analysis results, assisted by principal component and factorial discriminant analysis (PCA and FDA, respectively). The identified sesquiterpenes and ketones were found to strongly contribute to the characteristic flavour of the Brazilian cherry. The extracts also contained a variety of other volatile compounds, and part of the fruit wax contained long-chain hydrocarbons that according to multivariate analysis, contributed to the yield of the extracts, but not the flavour. Volatile phenolic compounds, to which antioxidant properties are attributed, were also present in the extracts in high proportion, regardless of the extraction conditions. (C) 2010 Elsevier Ltd. All rights reserved.

DYNAMIC AND STEADY-SHEAR RHEOLOGICAL PROPERTIES OF XANTHAN AND GUAR GUMS DISPERSED IN YELLOW PASSION FRUIT PULP (Passiflora edulis f. flavicarpa)

Yellow passion fruit pulp is unstable, presenting phase separation that can be avoided by the addition of hydrocolloids. For this purpose, xanthan and guar gum [0.3, 0.7 and 1.0% (w/w)] were added to yellow passion fruit pulp and the changes in the dynamic and steady-shear rheological behavior evaluated. Xanthan dispersions showed a more pronounced pseudoplasticity and the presence of yield stress, which was not observed in the guar gum dispersions. Cross model fitting to flow curves showed that the xanthan suspensions also had higher zero shear viscosity than the guar suspensions, and, for both gums, an increase in temperature led to lower values for this parameter. The gums showed different behavior as a function of temperature in the range of 5-35 degrees C. The activation energy of the apparent viscosity was dependent on the shear rate and gum concentration for guar, whereas for xanthan these values only varied with the concentration. The mechanical spectra were well described by the generalized Maxwell model and the xanthan dispersions showed a more elastic character than the guar dispersions, with higher values for the relaxation time. Xanthan was characterized as a weak gel, while guar presented a concentrated solution behavior. The simultaneous evaluation of temperature and concentration showed a stronger influence of the polysaccharide concentration on the apparent viscosity and the G` and G `` moduli than the variation in temperature.

Coupling Virus-Induced Gene Silencing to Exogenous Green Fluorescence Protein Expression Provides a Highly Efficient System for Functional Genomics in Arabidopsis and across All Stages of Tomato Fruit Development

Since the advent of the postgenomic era, efforts have focused on the development of rapid strategies for annotating plant genes of unknown function. Given its simplicity and rapidity, virus-induced gene silencing (VIGS) has become one of the preeminent approaches for functional analyses. However, several problems remain intrinsic to the use of such a strategy in the study of both metabolic and developmental processes. The most prominent of these is the commonly observed phenomenon of ""sectoring"" the tissue regions that are not effectively targeted by VIGS. To better discriminate these sectors, an effective marker system displaying minimal secondary effects is a prerequisite. Utilizing a VIGS system based on the tobacco rattle virus vector, we here studied the effect of silencing the endogenous phytoene desaturase gene (pds) and the expression and subsequent silencing of the exogenous green fluorescence protein (gfp) on the metabolism of Arabidopsis (Arabidopsis thaliana) leaves and tomato (Solanum lycopersicum) fruits. In leaves, we observed dramatic effects on primary carbon and pigment metabolism associated with the photobleached phenotype following the silencing of the endogenous pds gene. However, relatively few pleiotropic effects on carbon metabolism were observed in tomato fruits when pds expression was inhibited. VIGS coupled to gfp constitutive expression revealed no significant metabolic alterations after triggering of silencing in Arabidopsis leaves and a mild effect in mature green tomato fruits. By contrast, a wider impact on metabolism was observed in ripe fruits. Silencing experiments with an endogenous target gene of interest clearly demonstrated the feasibility of cosilencing in this system; however, carefully constructed control experiments are a prerequisite to prevent erroneous interpretation.

Ethylene and polyamine production patterns during in vitro shoot organogenesis of two passion fruit species as affected by polyamines and their inhibitor

Levels of ethylene and polyamines (PAs) were measured during organogenesis of hypocotyl explants of two species of passion fruit (Passiflora cincinnata Masters and Passiflora edulis Sims f. flavicarpa Degener `FB-100`) to better understand the relationships of these regulators and their influence on cell differentiation and morphogenesis. Moreover, histological investigation of shoot ontogenesis was conducted to characterize the different events involved in cell redifferentiation and regulation of PA and ethylene levels. A delay was observed in morphogenic responses of P. edulis f. flavicarpa as compared to P. cincinnata, and these changes coincided with production of elevated levels of polyamine and ethylene levels. During differentiation, cells showed high rates of expansion and elongation, and high ethylene levels were associated with high PA levels, suggesting that the two biosynthesis pathways were highly regulated. Moreover, their interaction might be an important factor for determining cell differentiation. The addition of PAs to the culture medium did not promote organogenesis; however, the incorporation of the PA inhibitor methylglyoxal bisguanylhydrazone in the culture medium reduced shoot bud differentiation, suggesting the need to maintaining a minimum level of PAs for morphogenic events to take place.

A novel regeneration system for a wild passion fruit species (Passiflora cincinnata Mast.) based on somatic embryogenesis from mature zygotic embryos

The objective of the present work was to induce somatic embryogenesis from zygotic embryos of Passiflora cincinnata Masters. Zygotic embryos formed calli on media with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4.5 mu M benzyladenine (BA) after 30 days of in vitro culture. A concentration of 18.1 mu M 2,4-D resulted in the largest number of somatic embryos. Embryogenic calli were yellowish and friable, forming whitish proembryogenic masses. Morphologically, embryogenic cells were small and had large nuclei and dense cytoplasm, whereas non-embryogenic cells were elongated, with small nuclei and less dense cytoplasm. Calli cultured under white light on basal Murashige and Skoog`s medium with activated charcoal produced embryos in all developmental stages. There were differences among the treatments, with some leading to the production of calli with embryos and some only to callus formation. Some abnormalities were associated with somatic embryos, including fused axes, fused cotyledons and polycotyledonary embryos. Production of secondary somatic embryos occurred in the first cycle of primary embryo development. Secondary embryos differentiated from the surface of the protodermal layer of primary embryos with intense cell proliferation, successive mitotic divisions in the initial phase of embryoid development, and a vascular system formed with no connection to the parental tissue. This secondary embryogenic system of P. cincinnata is characterized by intense proliferation and maintenance of embryogenic competence after successive subcultures. This reproducible protocol opens new prospects for massive propagation and is an alternative to the current organogenesis-based transformation protocol.

The modularity of seed dispersal: differences in structure and robustness between bat- and bird-fruit networks

In networks of plant-animal mutualisms, different animal groups interact preferentially with different plants, thus forming distinct modules responsible for different parts of the service. However, what we currently know about seed dispersal networks is based only on birds. Therefore, we wished to fill this gap by studying bat-fruit networks and testing how they differ from bird-fruit networks. As dietary overlap of Neotropical bats and birds is low, they should form distinct mutualistic modules within local networks. Furthermore, since frugivory evolved only once among Neotropical bats, but several times independently among Neotropical birds, greater dietary overlap is expected among bats, and thus connectance and nestedness should be higher in bat-fruit networks. If bat-fruit networks have higher nestedness and connectance, they should be more robust to extinctions. We analyzed 1 mixed network of both bats and birds and 20 networks that consisted exclusively of either bats (11) or birds (9). As expected, the structure of the mixed network was both modular (M = 0.45) and nested (NODF = 0.31); one module contained only birds and two only bats. In 20 datasets with only one disperser group, bat-fruit networks (NODF = 0.53 +/- A 0.09, C = 0.30 +/- A 0.11) were more nested and had a higher connectance than bird-fruit networks (NODF = 0.42 +/- A 0.07, C = 0.22 +/- A 0.09). Unexpectedly, robustness to extinction of animal species was higher in bird-fruit networks (R = 0.60 +/- A 0.13) than in bat-fruit networks (R = 0.54 +/- A 0.09), and differences were explained mainly by species richness. These findings suggest that a modular structure also occurs in seed dispersal networks, similar to pollination networks. The higher nestedness and connectance observed in bat-fruit networks compared with bird-fruit networks may be explained by the monophyletic evolution of frugivory in Neotropical bats, among which the diets of specialists seem to have evolved from the pool of fruits consumed by generalists.