Venus's southern polar vortex reveals precessing circulation     

Luz D  Berry DL  Piccioni G  Drossart P  Politi R  Wilson CF  Erard S  Nuccilli F 《Science (New York, N.Y.)》2011,332(6029):577-580

Initial images of Venus's south pole by the Venus Express mission have shown the presence of a bright, highly variable vortex, similar to that at the planet's north pole. Using high-resolution infrared measurements of polar winds from the Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, we show the vortex to have a constantly varying internal structure, with a center of rotation displaced from the geographic south pole by ~3 degrees of latitude and that drifts around the pole with a period of 5 to 10 Earth days. This is indicative of a nonsymmetric and varying precession of the polar atmospheric circulation with respect to the planetary axis.  相似文献   

Effect of dextransucrase cellobiose acceptor products on the growth of human gut bacteria     

Ruiz-Matute AI  Brokl M  Sanz ML  Soria AC  Côté GL  Collins ME  Rastall RA 《Journal of agricultural and food chemistry》2011,59(8):3693-3700

The selective fermentation by human gut bacteria of gluco-oligosaccharides obtained from the reaction between the glucosyl group of sucrose and cellobiose, catalyzed by dextransucrases (DSR) from Leuconostoc mesenteroides , has been evaluated. Oligosaccharides were fractionated according to their molecular weight, and their effect on the growth of different bacterial groups was studied. To determine the structure (position and configuration of glycosidic linkages)-function relationship, their properties were compared to those of DSR maltose acceptor products (DSRMal) and of recognized prebiotic carbohydrates (fructo-oligosaccharides, FOS). Cellobiose acceptor products (DSRCel) showed bifidogenic properties similar to those of FOS. However, no significant differences related to molecular weight or isomeric configurations were found for DSRCel and DSRMal products.  相似文献   

Influence of disaccharide structure on prebiotic selectivity in vitro     

Sanz ML  Gibson GR  Rastall RA 《Journal of agricultural and food chemistry》2005,53(13):5192-5199

To obtain structure-function information of a range of carbohydrates, which are available only in very small quantities, an in vitro fermentation method using 7 mg of carbohydrate, 0.7 mL of basal medium, and 1% (w/v) of fecal bacteria was validated against a pH-controlled batch culture with 150 mL of basal medium and 1.5 g of test carbohydrate. This method was used to determine the influence of different glycosidic linkages and monosaccharide compositions of disaccharides on the selectivity of microbial fermentation. A prebiotic index (PI) was calculated for each disaccharide. Generally, disaccharides with linkages of 1-2, 1-4, and 1-6 generated a high PI score, with kojibiose and sophorose showing the greatest values (21.62 and 18.63, respectively). Apart from 6alpha-mannobiose, mannose-containing disaccharides gave a low PI due to low numbers of bifidobacteria and lactobacilli and an increase in bacteroides. The structure-function information obtained in this study may lead to a predictive understanding of how specific structures are fermented by the human gut microflora.  相似文献   

2-Furoylmethyl amino acids and hydroxymethylfurfural as indicators of honey quality     

Sanz ML  del Castillo MD  Corzo N  Olano A 《Journal of agricultural and food chemistry》2003,51(15):4278-4283

Determination of changes in 2-furoylmethyl amino acids and hydroxymethylfurfural during the storage of four honey samples at 25 and 35 degrees C during 12 months was achieved to assess the potential use of both parameters, singly or in combination, as quality indicators. 2-Furoylmethyl amino acids increased during storage at both temperatures, whereas hydroxymethylfurfural only presented slight variations during storage at 25 degrees C but increased noticeably at 35 degrees C. The study of 2-furoylmethyl amino acids in 49 commercial honeys revealed that 2-furoylmethyl lysine (furosine) was present in all samples, whereas 2-furoylmethyl derivatives of arginine, GABA, and proline were only present in seven samples. Hydroxymethylfurfural can be considered as a good indicator of heat treatments applied to honey samples, whereas 2-furoylmethyl amino acids can be used as suitable markers of the storage period. The use of both parameters can be useful to detect adulteration with invert syrups, excessive heat treatments, or prolonged storage of honey samples.  相似文献   

Fresh-weight measurements of roots provide inaccurate estimates of the effects of plant growth-promoting bacteria on root growth: a critical examination     

Yoav Bashan  Luz E. de-Bashan 《Soil biology & biochemistry》2005,37(10):1795-1804

Four strains of plant growth-promoting bacteria (PGPB), including three strains of Azospirillum and Pseudomonas fluorescens 313 were used to inoculate seeds of wheat, tomato, pepper, and cotton. Inoculated seedlings were grown to the two or three-leaf stage. After harvest, seven different environmental and technical conditions were evaluated to determine the effect of these conditions on the reproducibility of fresh and dry root weight measurements. Dry root weight of each sample showed no significant variations (smaller than 1%), despite the variations in measurement conditions. Root fresh weights varied greatly (usually in the range of 4-10%, but up to 18%), and were significantly affected (P≤0.05) by air temperature and relative humidity, air currents, different light intensities during extraction of plants from the substrate, duration of the extraction from soil (depending on the size of the experiment and type of plant growth substrate), and the type of absorbing paper used to blot excess water from harvested roots. Measurements by different technicians did not influence fresh or dry weight values. We conclude that fresh weight determinations are altered by factors independent of the intended experimental variables and should not be used to evaluate the effect of PGPB on plants.  相似文献   

Eucharis Grandiflora Planch. and Linden Development Fertirrigated with Different Osmotic Potentials     

Silvia Evangelista-Lozano  Maribel Estrada-García  Sandra Luz Escobar-Arellano  Martha Lucia Arenas-Ocampo  Brenda Hildeliza Camacho-Díaz 《Journal of plant nutrition》2015,38(4):551-567

Eucharis grandiflora Planch. and Linden is a tropical climate Amaryllidacea, commonly known as lily, which develops a bulbous stem and is considered an indoor ornamental plant for its evergreen foliage and inflorescence. The aim of this study was to evaluate the vegetative development of the Lily, in response to the treatment with of the Steiner solution at different concentrations. The plants were acclimated under greenhouse conditions and the bulbs selected by a completely randomized design. Plants were treated with various concentrations of the Steiner solution, to develop the following potential osmotic: ?0.018, ?0.036, ?0.054, ?0.072, and 0 Mpal. The production of bulbils, development and leaf area, stomatal density, chlorophyll quantification, and osmotic potentials were evaluated. The results showed that treatment with solutions of ?0.054 and ?0.072 MPa induced a greater vegetative growth, 29.5% more stomata developed, and synthesized 29% more chlorophyll “b” than the control.  相似文献   

Influence of glycosidic linkages and molecular weight on the fermentation of maltose-based oligosaccharides by human gut bacteria     

Sanz ML  Côté GL  Gibson GR  Rastall RA 《Journal of agricultural and food chemistry》2006,54(26):9779-9784

A structure-function study was carried out to increase knowledge of how glycosidic linkages and molecular weights of carbohydrates contribute toward the selectivity of fermentation by gut bacteria. Oligosaccharides with maltose as the common carbohydrate source were used. Potentially prebiotic alternansucrase and dextransucrase maltose acceptor products were synthesized and separated into different molecular weights using a Bio-gel P2 column. These fractions were characterized by matrix-assisted laser desorption/ionization time-of-flight. Nonprebiotic maltooligosaccharides with degrees of polymerization (DP) from three to seven were commercially obtained for comparison. Growth selectivity of fecal bacteria on these oligosaccharides was studied using an anaerobic in vitro fermentation method. In general, carbohydrates of DP3 showed the highest selectivity towards bifidobacteria; however, oligosaccharides with a higher molecular weight (DP6-DP7) also resulted in a selective fermentation. Oligosaccharides with DPs above seven did not promote the growth of "beneficial" bacteria. The knowledge of how specific structures modify the gut microflora could help to find new prebiotic oligosaccharides.  相似文献   

Long-term efficacy of trilostane administered twice daily in dogs with pituitary-dependent hyperadrenocorticism     

Alenza DP  Arenas C  Lopez ML  Melian C 《Journal of the American Animal Hospital Association》2006,42(4):269-276

Trilostane is considered an efficacious and safe medication for canine pituitary-dependent hyperadrenocorticism (PDH). Its recommended frequency of administration is once daily. In this prospective study, the efficacy, toxicity, and long-term outcome of trilostane administered twice daily per os were evaluated in 44 dogs with PDH. Mean initial dose was 3.1 mg/kg q 12 hours, and mean final dose was 3.2 mg/kg q 12 hours. The final total daily dose was lower than previously reported for once-daily administration. The mean survival time for affected dogs was 930 days.  相似文献   

Changing Concentrations of Heavy Metals in Stream Water as a Result of Slurry Application to Soil     

M.  Mercedes  Taboada-Castro  M.  Luz.  Rodriguez-Blanco Antonio  Dieguez M. Teresa  Taboada-Castro 《农业科学与技术》2012,(4):473-480

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Occurrence of pathogenic fungi to Amblyomma cajennense in a rural area of Central Brazil and their activities against vectors of Rocky Mountain spotted fever     

D'Alessandro WB  Humber RA  Luz C 《Veterinary parasitology》2012,188(1-2):156-159

Two isolates of Beauveria bassiana and one of Purpureocillium lilacinum (=Paecilomyces lilacinus) were found infecting Amblyomma cajennense engorged females collected on horses (0.15% infection rate from a total of 1982 specimens) and another two isolates of P. lilacinum and one Metarhizium anisopliae detected in soils (2.1% from 144 samples) collected in typical pasture habitats of this tick in Central Brazil from October 2009 to March 2011. Fungi were isolated from soils with Rhipicephalus sanguineus as surrogate baits. No fungi were found in ticks or soils during the driest months (May to August). Testing pathogenicity of fungi all R. sanguineus females were killed regardless of the isolate and fungi sporulated abundantly on the cadavers. A. cajennense was less susceptible to infection with P. lilacinum within 20 days than R. sanguineus. All three fungal species probably act as natural antagonists of A. cajennense particularly in the rainy season and have interest for integrate control of vectors of Rocky Mountain spotted fever.  相似文献