Aroma extract dilution analysis. Precision and optimal experimental design     

Ferreira V  Pet'ka J  Aznar M 《Journal of agricultural and food chemistry》2002,50(6):1508-1514

The odor thresholds of 12 different compounds have been determined in an AEDA experiment using a panel composed of 8 individuals. Only in one case is the distribution of thresholds among judges significantly different from the log-normal. The cause of that departure from normality seems to be a cross adaptation rather than anosmia. The standard deviations (SD) range from 2(0.7) to 2(4.1), with 2(1.8) as average. If the AEDA is carried out at a dilution rate, R, and dilution R(P) (where P = 0, 1, 2.) is the last one at which a compound was detected by a judge, the flavor dilution (FD) factor that should be provided for that judge is R(P+0.5). In the case where several judges carry out the AEDA, the FD for a given compound should be the geometric mean of the FD provided by all the judges. The SD of the distribution of FDs is related to that of the distribution of odor thresholds, but is strongly influenced by the dilution rate, R, being higher with higher R values. The relationship between both SDs can be used to determine the expected precision (measured as the geometric length of the 95% confidence interval) of the result of an AEDA experiment as a function of the dilution rate, the number of judges, and the SD of the distribution of thresholds. Different simulations have shown that in most cases, a dilution rate of 10 is the best option, and that lower dilution rates are advantageous only if the analyzed solution contains compounds with a very narrow distribution of thresholds.  相似文献   

Element distribution of some soils of continental Chile and the Antarctic peninsula. Projection to atmospheric pollution     

Adriana Carrasco  M.  Préndez  Margarita 《Water, air, and soil pollution》1991,57(1):713-722

Water, Air, & Soil Pollution - The elemental content of some soils of continental Chile and the Antarctic Peninsula are reported. The elements: Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb were...  相似文献   

Plant genotype and nitrogen fertilization effects on abundance and diversity of diazotrophic bacteria associated with maize (Zea mays L.)     

Andrea Rodríguez-Blanco  Margarita Sicardi  Lillian Frioni 《Biology and Fertility of Soils》2015,51(3):391-402

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Improved <Emphasis Type="Italic">S</Emphasis>-genotyping and new incompatibility groups in Japanese plum     

María E. Guerra  Margarita López-Corrales  Ana Wünsch 《Euphytica》2012,186(2):445-452

The selection of cross-compatible cultivars is essential to ensure fruit set in self-incompatible species like Japanese plum and thus the S-genotype must be determined in order to establish incompatibility groups. In this study an improved Japanese plum S-genotyping method, based in polymerase chain reaction and capillary electrophoresis detection of intron polymorphisms of S-locus genes, S-RNase and SFB, has been assayed and validated in a wide sample of cultivars. This method allows a more precise determination of amplified fragment sizes and therefore a better differentiation of self-incompatibility alleles. The assayed methodology was proven effective in the detection of 13 different S-alleles of S-RNases and SFBs and was used to S-genotype 105 Japanese plum cultivars, 32 of which are described by first time in this work. Analysed cultivars were assigned into 11 incompatibility groups and two new incompatibility groups (XX and XXI) were identified, increasing to 21 the number of incompatibility groups described in this crop.  相似文献   

Reports on establishing an ex situ site for ‘beautiful’ vavilovia (Vavilovia formosa) in Armenia     

Janna Akopian  Nune Sarukhanyan  Ivan Gabrielyan  Armen Vanyan  Aleksandar Mikić  Petr Smýkal  Gregory Kenicer  Margarita Vishnyakova  Andrey Sinjushin  Natalia Demidenko  Mike Ambrose 《Genetic Resources and Crop Evolution》2010,57(8):1127-1134

Vavilovia (Vavilovia Fed.) is one of the five genera in tribe Fabeae and consists of only one species, ‘beautiful’ vavilovia (Vavilovia formosa (Stev.) Fed.). The main centre of distribution is the Central and Eastern Caucasus, with a disjunct distribution among high alpine areas in the region, extending as far as West Turkey, Lebanon and Iran. In Armenia, in situ studies on Vavilovia started in the late 1930s. In July and August 2009, three expeditions were conducted to two locations: two to the Ughtasar Mountain and one to the Geghama Mountains. The first expedition to Ughtasar resulted in fresh plant collections and soil analysis for one of the sites. The expedition to Geghama established the existence of Vavilovia in the region of Lake Aknalitch. The second expedition to Ughtasar provided immature fruits and seeds. Collected plant material was transplanted into the Flora and Vegetation of Armenia plot of the Yerevan Botanic Garden established in 1940. Today, along with other plants the plot contains more than 200 species of wild relatives of cultural plants from 130 genera, including indiginous species of tribe Fabeae such as Vavilovia. The transplanted plants will continue to be monitored to see if the plants go on to successfully flower and set seed or whether further sites, possibly at higher altitudes might need to be tested to meet the long term conservation requirements of this iconic legume. These co-ordinated efforts provide a good example of an ex situ conservation strategy for Vavilovia formosa, which, if successful will improve access and utility for the whole legume research community.  相似文献   

Interrelations of vegetal cover,silicophytolith content and pedogenesis of Typical Argiudolls of the Pampean Plain,Argentina     

Natalia Borrelli  Margarita Osterrieth  Jorge Marcovecchio 《CATENA》2008

Knowledge of the origin, evolution and weathering of Pampean soils is still limited. There are few prior studies of silicophytoliths, even though they could be important pedogenetic indicators that provide information about the role of amorphous silica in the reestablishment of soil structure. The aim of this work is to determine the silicophytolith content in Typical Argiudolls of the Pampean Plain, Argentina, its relation with vegetal cover and its effect on pedogenesis. We worked in three plots with different vegetal cover: grasses and shelter-belt plantations of Acacia melanoxylon – Celtis tala and Eucalyptus globulus – Celtis tala. In the study area, morphological characterization and particle size distribution analysis of soils were completed, and pH and organic matter content were determined. The heavy liquid separation was realized with sodium polytungstate (δ = 2.3 g/cm³) and an average of around 500 mineral grains were counted under optical microscope for the quali-quantitative analysis. There were no differences between profiles with respect to their morphological properties, organic matter content and particle size distribution, except for the higher organic horizon development of the forest plots as compared with the grass plot. The silicophytolith content was higher in the forest plots than in the grass one; within each profile, this fraction content decreased from the surface (63–40%) to the subsurface levels (23–5%) of soils. This decrease parallels the pieces of amorphous silica (< 7.5 μm) distribution in all plots analyzed. Afforestation over the past 50 years does not affect either the morphological or the physico-chemical properties of soils. These forest species, through the organic horizons, preserve soil conditions, which insures a higher representativity of silicophytoliths in comparison with the grass plot.  相似文献   

Persistence and molecular evolution of Mycobacterium bovis population from cattle and wildlife in Doñana National Park revealed by genotype variation     

Romero B  Aranaz A  Sandoval A  Alvarez J  de Juan L  Bezos J  Sánchez C  Galka M  Fernández P  Mateos A  Domínguez L 《Veterinary microbiology》2008,132(1-2):87-95

The role of wildlife in tuberculosis epidemiology is being widely studied since it can affect the effectiveness of eradication campaigns in cattle. The health problem is enhanced when it concerns also wildlife welfare and biodiversity conservation. This study was performed to understand the epidemiology of Mycobacterium bovis population affecting livestock and wild animals in the Do?ana National Park using bacteriology and molecular characterisation techniques. Tuberculosis research was performed on 1209 cattle and wild animals (artiodactyla and carnivore) collected over 6 years in the Park. One hundred and sixty-three animals were found to be infected with M. bovis, comprising 7.96% of the cattle and 20.53% of the wild animals tested. Spoligotyping revealed nine patterns, being SB1232 and SB1230 the most prevalent (77.30% and 15.34% of infected animals, respectively). MIRU-VNTR analysis of a selected panel of 92 isolates showed eight different profiles, including several spoligotypes within the same MIRU-VNTR profile. The discriminatory capacity of both techniques in this panel was similar. The results obtained by combination of both techniques corroborate that wildlife species are infected with the M. bovis strains which are more prevalent in cattle and reveal their persistence. Genotype variation between isolates strongly suggests micro-evolutionary events in the M. bovis population in the same area. This study in the Do?ana National Park exposes the risk of introduction of domestic animals into wildlife areas when there is not a warranty of disease freedom, appropriate diagnostic techniques and control measures.  相似文献   

Pharmacokinetics and pharmacologic effects of the S(-) isomer of bupivacaine after intravenous and epidural administration in dogs.     

C Franquelo  A Toledo  J Manubens  J E Valladares  C Cristòfol  M Arboix 《American journal of veterinary research》1999,60(7):832-835

OBJECTIVE: To determine pharmacokinetic variables and pharmacologic effects of the S(-) isomer of bupivacaine (S[-]-BPV) in dogs. ANIMALS: 6 adult male Beagles. PROCEDURE: Dogs received S(-)-BPV (1 mg/kg of body weight) i.v., and 15 days later, the same dogs received 1.8 mg/kg epidurally. Pharmacokinetic variables and pharmacologic effects were determined for each route of administration. RESULTS: After i.v. administration, plasma concentration versus time curves were adjusted, using biexponential equations that indicated a rapid distribution phase followed by a slower elimination phase, with a mean +/- SD half-life of 33.5 +/- 17.0 minutes. Mean plasma clearance was 21.0 +/- 10.7 ml/min/kg, and mean volume of distribution at steady state was 0.8 +/- 0.2 L/kg. After i.v. administration, mean peak plasma concentration was 2.6 +/- 0.7 micrograms/ml; after epidural administration, it was 0.9 +/- 0.5 microgram/ml at approximately 3 minutes. Half-life after epidural administration was 5 times longer than that observed after i.v. administration. Motor block began immediately after the end of epidural administration and lasted for 3 to 4 hours. Changes in systolic blood pressure and heart rate after epidural administration were slight but occurred at the same time that plasma concentration peaked. After i.v. administration, motor block or variations in physiologic variables studied were not observed. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, the pharmacologic behavior of S(-)-BPV was similar to that of the bupivacaine racemate, but motor block attributable to S(-)-BPV lasted longer than that attributable to the racemate, with lower plasma concentrations observed at equivalent sample collection times.  相似文献   

Inter‐annual variability in amphibian assemblages: implications for diversity assessment and conservation     

Carola Gómez‐Rodríguez  Carmen Díaz‐Paniagua  Javier Bustamante  Alexandre Portheault  Margarita Florencio 《水产资源保护:海洋与淡水生态系统》2010,20(6):668-677

• 1. Diversity assessments and conservation management should take into account the dynamic nature of populations and communities, particularly when they are subject to highly variable and unpredictable environmental conditions.
• 2. This study evaluates the inter‐annual variability in the assemblage composition (temporal turnover) of an amphibian community breeding in a highly dynamic habitat, a Mediterranean temporary pond system, during a 4‐year period.
• 3. A comprehensive framework is provided to evaluate temporal turnover from data of a differing nature (species richness, presence/absence and relative abundance) and, especially, to discern variation in richness (species loss) from changes in the identity or abundance of species (species replacement).
• 4. Results show that the pond amphibian assemblages in Doñana National Park exhibited high inter‐annual variability during the study period, both in the number of species, species identity and their relative abundance. This result provides evidence for the inadequacy of surveys conducted only in one breeding season to characterize the species assemblage associated with a given pond. Besides, it suggests that a given pond offers different breeding opportunities over time, being suitable for different species depending on the year. This alternation will contribute to the medium‐term preservation of all species in the assemblage.
• 5. It is highly relevant to preserve the natural dynamism and spatial variability of temporary pond systems, which will favour the conservation of populations through their intrinsic variability. Copyright © 2010 John Wiley & Sons, Ltd.

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Rapid sequence modification in the highly polymorphic region (HPR) of the hemagglutinin gene of the infectious salmon anaemia virus (ISAV) suggests intra-segmental template switching recombination     

Matías Cárdenas  Claudia Galleguillos  Karina Acevedo  Catarina Ananias  Javiera Alarcón  Sofía Michelson  Jorge Toledo  Margarita Montoya  Claudio Meneses  Eduardo Castro-Nallar  Yesseny Vásquez-Martínez  Marcelo Cortez-San Martin 《Journal of fish diseases》2020,43(12):1483-1496

The ISAV has a genome composed of eight segments of (–)ssRNA, segment 6 codes for the hemagglutinin–esterase protein, and has the most variable region of the genome, the highly polymorphic region (HPR), which is unique among orthomyxoviruses. The HPR has been associated with virulence, infectivity and pathogenicity. The full length of the HPR is called HPR0 and the strain with this HPR is avirulent, in contrast to strains with deleted HPR that are virulent to varying degrees. The molecular mechanism that gives rise to the different HPRs remains unclear. Here, we studied in vitro the evolution of reassortant recombinant ISAV (rISAV) in Atlantic salmon head kidney (ASK) cells. To this end, we rescued and cultivated a set of rISAV with different segment 6-HPR genotypes using a reverse genetics system and then sequencing HPR regions of the viruses. Our results show rapid multiple recombination events in ISAV, with sequence insertions and deletions in the HPR, indicating a dynamic process. Inserted sequences can be found in four segments of the ISAV genome (segments 1, 5, 6, and 8). The results suggest intra-segmental heterologous recombination, probably by class I and class II template switching, similar to the proposed segment 5 recombination mechanism.  相似文献