UBVJHKLM photometry and modeling of R Coronae Borealis

We present the results of UBVJHKLM photometry of R CrB spanning the period from 1976 to 2001. Studies of the optical light curve have shown no evidence of any stable harmonics in the variations of the stellar emission. In the L band we found semi-regular oscillations with the two main periods of ~3.3 yr and 11.9 yr and the full amplitude of ~0.8 mag and ~0.6 mag, respectively. The colors of the warm dust shell (resolved by Ohnaka et al. 2001) are found to be remarkably stable in contrast to its brightness. This indicates that the inner radius is a constant, time-independent characteristic of the dust shell. The observed behavior of the IR light curve is mainly caused by the variation of the optical thickness of the dust shell within the interval \tau(V)= 0.2-0.4. Anticorrelated changes of the optical brightness (in particular with P ~ 3.3 yr) have not been found. Their absence suggests that the stellar wind of R CrB deviates from spherical symmetry. The light curves suggest that the stellar wind is variable. The variability of the stellar wind and the creation of dust clouds may be caused by some kind of activity on the stellar surface. With some time lag, periods of increased mass-loss cause an increase in the dust formation rate at the inner boundary of the extended dust shell and an increase in its IR brightness. We have derived the following parameters of the dust shell (at mean brightness) by radiative transfer modeling: inner dust shell radius r_in ~ 110 R_*, temperature T_dust(r_in) ~ 860 K, dust density \rho_dust(r_in) ~ 1.1x10^{-20} g cm^-3, optical depth \tau(V) ~ 0.32 at 0.55 micron, mean dust formation rate [dM/dt]_dust ~ 3.1x10^-9 M_sun / yr, mass-loss rate [dM/dt]_gas ~ 2.1x10^-7 M_sun / yr, size of the amorphous carbon grains <(~) 0.01 micron, and B-V ~ -0.28.Comment: 9 pages, 6 figures, accepted for publication in A&

The balance between fumarate and malate plays an important role in plant development and postharvest quality in tomato fruit

Organic acids, produced as intermediates of the tricarboxylic cycle, play a crucial role in the plant primary metabolism and are considered as being ones of the most important quality traits in edible fruits. Even if they are key metabolites in a multitude of cellular functions, little is known about their physiological relevance and regulation. Transgenic tomato (Solanum lycopersicum) plants expressing constitutively a bacterial maleate isomerase, which converts reversibly maleate to fumarate, were generated in order to improve our knowledge about the role of organic acids in the crop and fruit metabolism. Growth and reproduction were affected by the unbalance of tricarboxylic cycle intermediates, as a dwarf phenotype and a flowering delay were observed in the transgenic plants. In addition, a delay in chlorophyll synthesis, a decrease in the numbers of stomata and significant changes in some photosynthetic parameters indicated alterations in central primary metabolism. Postharvest was also impaired, as transgenic fruits showed increased water lost and deterioration, indicating a possible role of the organic acids in cell wall metabolism. Finally, preliminary metabolomics analysis pointed out important changes during fruit ripening in flavor-related metabolites, such as acids and sugars, revealing the importance of organic acids in fruit metabolism. Taken together, these data indicate a pivotal role of tricarboxylic cycle intermediates, such as malate or fumarate, as regulatory metabolites. Besides their role in quality fruit characteristics, they are involved in a multitude of functions including growth and photosynthesis.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Metabolomics profiling of strawberry (Fragaria x ananassa) F1 population to characterize flavour and nutritional traits

The cultivated strawberry (Fragaria x ananassa) is a highly consumed fruit known for its delicate flavour and nutritional characteristics. However, as fruit quality attributes have been lost after years of traditional breeding, new technological tools, such as high throughput metabolomics, are necessary for the identification of factors responsible of these traits. Here we present the metabolomics profiling for the content of primary and secondary metabolites of a 95 F1 individuals strawberry population derived from genotype “1392”, selected for its superior flavour, and “232” (Zorrilla-Fontanesi et al., 2011; Zorrilla-Fontanesi et al., 2012). Metabolite profiling was performed on mature fruits of the strawberry population using gas chromatography hyphenated to time-of-flight mass spectrometry for primary metabolites and ultra performance liquid chromatography Exactive Orbitrap tandem mass spectrometry for secondary metabolites.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Alteration of the interconversion of pyruvate and malate in the plastid or cytosol of ripening tomato fruit invokes diverse consequences on sugar but similar effects on cellular organic Acid, metabolism, and transitory starch accumulation

The aim of this work was to investigate the effect of decreased cytosolic phosphoenolpyruvate carboxykinase (PEPCK) and plastidic NADP-dependent malic enzyme (NADP-ME) on tomato (Solanum lycopersicum) ripening. Transgenic tomato plants with strongly reduced levels of PEPCK and plastidic NADP-ME were generated by RNA interference gene silencing under the control of a ripening-specific E8 promoter. While these genetic modifications had relatively little effect on the total fruit yield and size, they had strong effects in fruit metabolism. Both transformants were characterized by lower levels of starch at breaker stage. Analysis of the activation state of ADP-glucose pyrophosphorylase correlated with the decrease of starch in both transformats, which suggest that is due to an altered cellular redox status. Moreover, metabolic profiling and feeding experiments involving positional labelled glucoses of fruits lacking in plastidic NADP-malic enzyme and cytosolic PEPCK activities revealed differential changes in overall respiration rates and tricarboxylic acid (TCA) cycle flux. Inactivation of cytosolic PEPCK affected the respiration rate which suggests that excess of oxaloacetate OAA is converted to aspartate and reintroduced in the TCA via 2-oxoglutarate/glutamate. On the other hand, the plastidic NADP-malic enzyme antisense lines were characterized by no changes in respiration rates and TCA cycle flux and together with an increase of pyruvate kinase and phosphoenolpyruvate carboxylase activities indicates that pyruvate is supply through these enzymes to the TCA cycle. These results are discussed in the context of current models of the importance of malate during tomato fruit ripening

QTLs mapping for primary metabolites responsible of the organoleptic and nutritional characteristics of strawberry (Fragaria x ananassa)

The cultivated strawberry (Fragaria x ananassa) is the berry fruit most consumed worldwide and is well-known for its delicate flavour and nutritional properties. However, fruit quality attributes have been lost or reduced after years of traditional breeding focusing mainly on agronomical traits. To face the obstacles encountered in the improvement of cultivated crops, new technological tools, such as genomics and high throughput metabolomics, are becoming essential for the identification of genetic factors responsible of organoleptic and nutritive traits. Integration of “omics” data will allow a better understanding of the molecular and genetic mechanisms underlying the accumulation of metabolites involved in the flavour and nutritional value of the fruit. To identify genetic components affecting/controlling? fruit metabolic composition, here we present a quantitative trait loci (QTL) analysis using a 95 F1 segregating population derived from genotypes ‘1392’, selected for its superior flavour, and ‘232’ selected based in high yield (Zorrilla-Fontanesi et al., 2011; Zorrilla-Fontanesi et al., 2012). Metabolite profiling was performed on red stage strawberry fruits using gas chromatography hyphenated to time-of-flight mass spectrometry, which is a rapid and highly sensitive approach, allowing a good coverage of the central pathways of primary metabolism. Around 50 primary metabolites, including sugars, sugars derivatives, amino and organic acids, were detected and quantified after analysis in each individual of the population. QTL mapping was performed on the ‘232’ x ‘1392’ population separately over two successive years, based on the integrated linkage map (Sánchez-Sevilla et al., 2015). First, significant associations between metabolite content and molecular markers were identified by the non-parametric test of Kruskal-Wallis. Then, interval mapping (IM), as well as the multiple QTL method (MQM) allowed the identification of QTLs in octoploid strawberry. A permutation test established LOD thresholds for each metabolite and year. A total of 132 QTLs were detected in all the linkage groups over the two years for 42 metabolites out of 50. Among them, 4 (9.8%) QTLs for sugars, 9 (25%) for acids and 7 (12.7%) for amino acids were stable and detected in the two successive years. We are now studying the QTLs regions in order to find candidate genes to explain differences in metabolite content in the different individuals of the population, and we expect to identify associations between genes and metabolites which will help us to understand their role in quality traits of strawberry fruit.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. The work was supported by the MINECO (grant AGL2012-40066-C02-02 ; Spain). SO aknowledges the support by Spanish Ministry of Science and Innovation (Ramón and Cajal contract, RYC2011-09170). DP has received a predoctoral grant from MINECO (grant BES-2013-062856). JJM and IA has been supported by the grant AGL2012-40066-C02-01). The authors also aknowlegde the support by the University de Málaga, Campus de Excelencia Internacional de Andalucía

Chloroplast-localized 6-phosphogluconate dehydrogenase is critical for maize endosperm starch accumulation

Plants have duplicate versions of the oxidative pentose phosphate pathway (oxPPP) enzymes with a subset localized to the chloroplast. The chloroplast oxPPP provides NADPH and pentose sugars for multiple metabolic pathways. This study identified two loss-of-function alleles of the Zea mays (maize) chloroplast-localized oxPPP enzyme 6-phosphogluconate dehydrogenase (6PGDH). These mutations caused a rough endosperm seed phenotype with reduced embryo oil and endosperm starch. Genetic translocation experiments showed that pgd3 has separate, essential roles in both endosperm and embryo development. Endosperm metabolite profiling experiments indicated that pgd3 shifts redox-related metabolites and increases reducing sugars similar to starch-biosynthetis mutants. Heavy isotope-labelling experiments indicates that carbon flux into starch is altered in pgd3 mutants. Labelling experiments with a loss of cytosolic 6PGDH did not affect flux into starch. These results support the known role for plastid-localized oxPPP in oil synthesis and argue that amyloplast-localized oxPPP reactions are integral to endosperm starch accumulation in maize kernels

Reddenings of FGK supergiants and classical Cepheids from spectroscopic data

Accurate and homogeneous atmospheric parameters (Teff, log (g), Vt, [Fe/H]) are derived for 74 FGK non-variable supergiants from high-resolution, high signal-to-noise ratio, echelle spectra. Extremely high precision for the inferred effective temperatures (10-40 K) is achieved by using the line-depth ratio method. The new data are combined with atmospheric values for 164 classical Cepheids, observed at 675 different pulsation phases, taken from our previously published studies. The derived values are correlated with unreddened B-V colours compiled from the literature for the investigated stars in order to obtain an empirical relationship of the form: (B-V)o = 57.984 - 10.3587(log Teff)^2 + 1.67572(log Teff)^3 - 3.356(log (g)) + 0.0321(Vt) + 0.2615[Fe/H] + 0.8833((log (g))(log Teff)). The expression is used to estimate colour excesses E(B-V) for individual supergiants and classical Cepheids, with a precision of +-0.05 mag. for supergiants and Cepheids with n=1-2 spectra, reaching +-0.025 mag. for Cepheids with n>2 spectra, matching uncertainties for the most sophisticated photometric techniques. The reddening scale is also a close match to the system of space reddenings for Cepheids. The application range is for spectral types F0--K0 and luminosity classes I and II.Comment: accepted for publication (MNRAS

Classical Cepheid Pulsation Models: IX. New Input Physics

We constructed several sequences of classical Cepheid envelope models at solar chemical composition ($Y=0.28, Z=0.02$) to investigate the dependence of the pulsation properties predicted by linear and nonlinear hydrodynamical models on input physics. To study the dependence on the equation of state (EOS) we performed several numerical experiments by using the simplified analytical EOS originally developed by Stellingwerf and the recent analytical EOS developed by Irwin. Current findings suggest that the pulsation amplitudes as well as the topology of the instability strip marginally depend on the adopted EOS. We also investigated the dependence of observables predicted by theoretical models on the mass-luminosity (ML) relation and on the spatial resolution across the Hydrogen and the Helium partial ionization regions. We found that nonlinear models are marginally affected by these physical and numerical assumptions. In particular, the difference between new and old models in the location as well as in the temperature width of the instability strip is on average smaller than 200 K. However, the spatial resolution somehow affects the pulsation properties. The new fine models predict a period at the center of the Hertzsprung Progression ($P_{HP}=9.65$$-$9.84 days) that reasonably agree with empirical data based on light curves ($P_{HP}=10.0\pm 0.5$ days; \citealt{mbm92}) and on radial velocity curves ($P_{HP}=9.95\pm 0.05$ days; \citealt{mall00}), and improve previous predictions by Bono, Castellani, and Marconi (2000, hereinafter BCM00).Comment: 35 pages, 7 figures. Accepted for publication in the Astrophysical Journa

Metabolite profiling of postharvest senescence in different strawberry cultivars

The cultivated strawberry (Fragaria x ananassa) is the berry most consumed worldwide, being well appreciated for its flavour and nutritional characteristics. However, strawberries possess a very short postharvest shelf-life due to their high respiration rate and their susceptibility to water loss, mechanical damage and fungi deterioration (Feliziani and Romanazzi, 2016). Extension of fruit shelf-life is a major economic goal, and measures are commercially taken to delay senescence, including the use of low temperature storage alone or in combination with controlled atmosphere (Pedreschi and Lurie, 2015). To improve our understanding of the molecular and biochemical mechanisms underlying the deterioration of fruit quality attributes during senescence, we realized a metabolite profiling of five commercial strawberry cultivars under different postharvest treatments. Ripe fruits were harvested and kept at 4ºC during three, six and ten days in ambient, CO2-enriched and O3-enriched atmospheres. We used a combination of gas chromatography-mass spectrometry (GC-TOF-MS), ultra-performance liquid chromatography-Orbitrap mass/mass spectrometry (UPLC-Orbitrap-MS/MS) and headspace solid phase micro extraction (HS-SPME) coupled with GC-MS to identify and semi-quantify 49 primary metabolites (sugars, amino and organic acids), 132 polar secondary metabolites (mainly polyphenols) and 70 volatile compounds. Multivariate statistical approaches were used to characterize the variation in metabolite content during the strawberry fruit postharvest life and to identify the biochemical pathways which are most affected in the senescence processes. Preliminary analysis pointed out that changes in primary metabolism were possibly related to responses to abiotic stress.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

E-grocery challenges and remedies: Global market leaders perspective

The purpose of the study is to identify logistic elements germane to e-grocery businesses, and to reveal the challenges collateral with each logistic element. Further, it strives to create a better understanding of specific remedies that have been employed by top e-grocery retailers to overcome existing challenges while aligning identified challenges with Turban’s framework. Extensive semi-structured interviews were conducted with management staff in three of the top ten global online grocery retailers and another that was a market leader in a European country. The qualitative data collected was transcribed and coded using a non-hierarchical axial coding to identify emerging themes in content analysis. The results expose a range of challenges that could be compartmentalised into three broad categories, in harmony with the different stages of the order fulfilment process. Interestingly, the study found that most challenges were operational rather than tactical or strategic in nature. While the study expands existing knowledge, its revelation that most challenges lie in the management of roles and responsibilities domain is instructive. This makes it imperative for practitioners to focus on this specific area if meaningful improvement in e-grocery retailing performance is to be realised. This research offers a systematic understanding of supply and distribution challenges, including remedies utilised to ameliorate the effect of the challenges from the perspectives of the top companies in the industry. These remedies can be invaluable for existing and emerging e-grocers