333,790 research outputs found

    Calibrating the Cepheid Period-Luminosity relation from the infrared surface brightness technique I. The p-factor, the Milky Way relations, and a universal K-band relation

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    We determine Period-Luminosity relations for Milky Way Cepheids in the optical and near-IR bands. These relations can be used directly as reference for extra-galactic distance determination to Cepheid populations with solar metallicity, and they form the basis for a direct comparison with relations obtained in exactly the same manner for stars in the Magellanic Clouds, presented in an accompanying paper. In that paper we show that the metallicity effect is very small and consistent with a null effect, particularly in the near-IR bands, and we combine here all 111 Cepheids from the Milky Way, the LMC and SMC to form a best relation. We employ the near-IR surface brightness (IRSB) method to determine direct distances to the individual Cepheids after we have recalibrated the projection factor using the recent parallax measurements to ten Galactic Cepheids and the constraint that Cepheid distances to the LMC should be independent of pulsation period. We confirm our earlier finding that the projection factor for converting radial velocity to pulsational velocity depends quite steeply on pulsation period, p=1.550-0.186*log(P) in disagrement with recent theoretical predictions. We delineate the Cepheid PL relation using 111 Cepheids with direct distances from the IRSB analysis. The relations are by construction in agreement with the recent HST parallax distances to Cepheids and slopes are in excellent agreement with the slopes of apparent magnitudes versus period observed in the LMC.Comment: Accepted for publication by Astronomy and Astrophysics. 15 pages, 11 figure

    Occurrence of potassium location in oil palm tissues with reserve sugars: consequences for oil palm K status determination

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    In some fertilizer trials for oil palm, it is observed that potassium leaf content was not in concordance with potassium application. In some cases no "leaf" response is observed (leaflet potassium content from leaf rank 17 according to specific LD IRHO method) whatever the K level. Agronomists have suggested to look for potassium content in others organs like rachis, showing best adjustment between K content, yield and K application; This K content difference between rachis and leaflets may be related to their different metabolic role for the plant; When leaflets are devoted to photosynthetic acquisition of carbon for the whole plant, rachis play obviously a role in photosynthetic product transportation; Potassium is often mentioned as involved in sugars translocation. In order to explain K content variations within organs, an experimental observations design has been elaborated on a factorial fertilizer trial (ALCP 10, factorial K4 x Ca2 in North Sumatra) involving precise samplings on vegetative organs as leaflets petioles, rachis, trunk and roots as well as fruits, spikelets and bunch stalk. Both mineral content analyses and sugars content (soluble sugars and starch) were performed on a total of 36 oil palm trees belonging to two different contrasting genetic materials. For strengthening our hypotheses, two other set of data were overviewed for K and sugars locations; The first one is a complete dissection of a crown from very young bud leaf stage until old leaves, the second is an exploration of sugars reserves in the crown in North Sumatra conditions. Maximal K mineral content was observed in trunk bottom (for all planting material and treatment) when soluble sugars are high and starch low. Generally it has been observed that potassium is high in petiole of very young leaves (1 to 3) and increasing in bunch rachis until fruit maturation. Leaflets of young leaves (rank -2) contain more potassium that leaflets at rank 17 due to their high proportion in reserve sugars before starting strong photosynthetic activity. Hypothesis is merging from a high co-occurrence of K with soluble sugars in oil palm (most probably glucose) which are involved in the reserve mobilization to elaborate not only bunches but also new young leaves. An inverse relation is found between K concentration and starch.. It seems that equilibrium between starch and soluble sugars content at organs scale and the K level are a key to elaborate a clear K nutrient status for oil palm. (Résumé d'auteur

    Seasonal Response of Workers of the Allegheny Mound Ant, \u3ci\u3eFormica Exsectoides\u3c/i\u3e (Hymenoptera: Formicidae) to Artificial Honeydews of Varying Nutritional Content

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    Field colonies of Allegheny mound ants, Formica exsectoides, were tested at monthly intervals throughout the summer to assess their preference for artificial honeydews containing varying compositions of sugars and amino acids. In choice tests, foragers significantly preferred high sugar honeydews early in the season, but shifted in mid-season to a strong preference for high amino acid honeydews. Late-season foragers slightly preferred sugars. When offered in equal concentrations, the honeydew sugar, melezitose, was consistently less attractive to foragers than sucrose. However both sugars were readily fed upon, and appeared to attract ants in an additive fashion. No single amino acid was significantly preferred; however the combination of asparagine, glutamine and serine was highly attractive during the mid-season sampling period. The seasonal switch in forager preference between sugars and amino acids coincides with an increase in the amount of actively growing brood

    Impact of a new nucleo-cytoplasmic composition on the citrus fuit quality : [23]

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    Organic acids, sugars and carotenoids are implied in the fruit quality. A cybrid has been obtained by symmetric protoplast fusion between Willow leaf mandarin (Citrus deliciosa Ten.) and Eureka lemon (Citrus limon (L.) Buno.). The cybrid possessed nuclear genome and chloroplasts of Eureka lemon plus mitochondria from Willow leaf mandarin. Impact of new mitochondria on the internal fruit quality has been studied. Organic acids, sugars and carotenoids were quantified by HPLC on fruit pulp of Willow leaf mandarin, Eureka lemon and the cybrid. Compounds identified in cybrid fruit pulp were compared to those from fruits of his two diploid parents. The cybrid was found to be very close to lemon parent in biosynthesis of components involved in citrus fruit quality (Organic acids, sugars and carotenoids) although the presence of Willow leaf mandarin mitochondria in the cybrid cells. The results obtained confirm that the main genetic information for sugars, organic acids and carotenoids biosynthesis are contained in the nucleus. No significant difference is observed in sugars and carotenoid pulp fruit between the cybrid and the lemon but the organic acids level are slightly modified in quantity in the cybrid probably because of a nucleo-mitochondria interaction. Cybridisation should be used in citrus as a strategy to breed specific traits associated with mitochondrial genomes such as male sterility without affecting the main organoleptic and nutritional qualities. (Texte intégral

    Associations between dietary added sugar intake and micronutrient intake: a systematic review

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    Original article can be found at: http://journals.cambridge.org/ Copyright The Authors. DOI: 10.1017/S0007114507617206There is increasing concern that high intakes of added sugars might compromise intakes of micronutrients. The objectives of this systematic review were (1) to determine whether dietary added sugar intake was associated with micronutrient intakes, and if so, whether there was evidence of micronutrient dilution as a result of higher dietary added sugar intake and (2) if micronutrient dilution was present, to determine whether there was sufficiently robust evidence to support a threshold effect above which there was a significant decline in micronutrient intake or status relative to the recommended intakes. A systematic computerised literature search was undertaken, limited to studies written in English published from 1980 onwards and further studies identified through hand searching papers. Fifteen studies that assessed associations between intakes of added sugars or non-milk extrinsic sugars and micronutrients were included. Overall, there are insufficient data and inconsistency between studies in relationships between added sugars and micronutrient intakes, with no clear evidence of micronutrient dilution or a threshold for a quantitative amount of added sugar intake for any of the micronutrients investigated. The current evidence base is considerably constrained by methodological issues. Further research is required to determine which food products high in added sugars might adversely affect micronutrient intakes by displacing other food items from the diet. Analyses should take into account the magnitude of any observed associations to determine their true biological significance.Peer reviewe

    Determination of Soluble Sugars in Arabidopsis thaliana Leaves by Anion Exchange Chromatography

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    Determination of soluble sugars is basic for the study of carbon metabolism in plants. Soluble sugar quantitation can be achieved by enzymatic methods implying different coupled reactions. Here we describe a simple method that allows rapid determination of the most abundant soluble sugars (glucose, fructose and sucrose) in Arabidopsis leaves by anion exchange chromatography. We have applied this method to study the levels of soluble sugars during the photoperiodic transition to flowering (Ortiz-Marchena et al., 2014).España, MINECO projects CSD2007-00057, BIO2008-02292, and BIO2011-28847-C02-00España, Junta de Andalucía P06-CVI-01450 and P08-AGR-0358

    Evaluation of fruit quality in a lemon cybrid with mandarin mitochondria

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    Nutritional and organoleptic qualities of fruit are currently very important objectives for plant breeders. Organic acids, sugars and carotenoids were studied by high liquid chromatography on the pulp of a citrus cybrid. This cybrid named 'WLM + EUR' (Citrus deliciosa Ten.) + (Citrus limon (L.) Burm.), inherited nuclear and chloroplasts genomes of Eureka lemon (Citrus limon (L.) Burm.) plus mitochondria from Willow leaf mandarin (Citrus deliciosa Ten.). In our work, impact of new mitochondria on fruit quality was studied during the maturity period. We observed that the cybrid was different from willow leaf mandarin and close to lemon parent. Organic acids level is slightly increased in the cybrid fruit pulp compared to Eureka lemon. No significant difference is observed in sugars and carotenoids between the cybrid and the lemon. The results confirm that mains genetic information for sugars, organic acids and carotenoids biosynthesis are contained in the nucleus. Cybridisation should be used in citrus as a strategy to breed specifie traits associated with mitochondrial genomes such as male sterility without affecting the main organoleptic and nutritional qualities. (Texte intégral

    One-pot Enzymatic Synthesis of Deoxy-thymidine-diphosphate (TDP)-2-deoxy-∝-d-glucose Using Phosphomannomutase

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    Production of deoxy-thymidine-diphosphate (TDP)-sugars as substrates of glycosyltransferases, has been one of main hurdles for combinatorial antibiotic biosynthesis, which combines sugar moiety with aglycon of various antibiotics. Here, we report the one-pot enzymatic synthesis of TDP-2-deoxy-glucose employing high efficient TMP kinase (TMK; E.C. 2.7.2.12), acetate kinase (ACK; E.C. 2.7.1.21), and TDP-glucose synthase (TGS; E.C. 2.7.7.24) with phosphomannomutase (PMM; E.C. 5.4.2.8). In this study, replacing phosphoglucomutase (PGM; E.C. 5.4.2) by PMM from Escherichia coli gave four times higher specific activity on 2-deoxy-6-phosphate glucose, suggesting that the activity on 2-deoxy-glucose-6-phosphate was mainly affected by PMM activity, not PGM activity. Using an in vitro system starting from TMP and 2-deoxy-glucose-6-phosphate glucose, TDP-2-deoxy-glucose (63% yield) was successfully synthesized. Considering low productivity of NDP-sugars from cheap starting materials, this paper showed how production of NDP-sugars could be enhanced by controlling mutase activity

    Carbohydrate intake and cardiometabolic risk factors in high BMI African American children.

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    The aim of this study was to evaluate the relationship between intakes of subgroups of energy-providing carbohydrate, and markers of cardiometabolic risk factors in high BMI African American (AA) children.A cross sectional analysis was performed on data from a sample of 9-11 year old children (n = 95) with BMI greater than the 85th percentile. Fasting hematological and biochemical values for selected markers of cardiometabolic risk factors were related to intakes of carbohydrates and sugars.After adjusting for gender, pubertal stage and waist circumference, multivariate regression analysis showed that higher intakes of carbohydrate (with fat and protein held constant) were associated with higher plasma concentrations of triglycerides (TG), VLDL-C, IDL-C, and worse insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR). After dividing carbohydrate into non-sugar versus sugar fractions, sugars were significantly related to higher TG, VLDL-C, IDL-C, lower adipocyte fatty acid insulin sensitivity (ISI-FFA), and was closely associated with increased HOMA-IR. Similar trends were observed for sugars classified as added sugars, and for sugars included in beverages. Further dividing sugar according to the food group from which it was consumed showed that consuming more sugar from the candy/soda food group was highly significantly associated with increased TG, VLDL-C, IDL-C and closely associated with increased HOMA-IR. Sugars consumed in all fruit-containing foods were significantly associated with lower ISI-FFA. Sugars consumed as fruit beverages was significantly associated with VLDL-C, IDL-C and ISI-FFA whereas sugars consumed as fresh, dried and preserved fruits did not show significant associations with these markers.Sugars consumed from in all dairy foods were significantly associated with higher TG, VLDL-C and IDL-C, and with significantly lower HDL-C and ISI-FFA. These effects were associated with sugars consumed in sweetened dairy products, but not with sugars consumed in unsweetened dairy products. This analysis suggests that increases in carbohydrate energy, especially in the form of sugar, may be detrimental to cardiometabolic health in high BMI children
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