QTL mapping for the cooking time of common beans

The decrease in the per capita consumption of beans has been partially attributed to their lengthy cooking time and the aggregated capital costs of their preparation. The aim of this study was to map microsatellite (SSR) markers linked to quantitative trait loci (QTLs) that govern the cooking time of common beans. An F₂ generation consisting of 140 families was generated from a cross between lines CNFM7875 and Laranja. The cooking time of the F_2:4 and F_2:5 generations was then evaluated, and the latter generation was tested in two environments. The analysis of variance found a significant effect for the interactions between the families (P < 0.01) in both the F_2:4 and F_2:5 generations, as well as for the group analyses performed in the two environments. The experimental coefficient of variation varied from 9.42 to 17.94%. The Pearson’s correlation test indicated no significant association between water absorption and cooking time. The heritability coefficients had values of 0.532 and 0.739 for the F_2:5 families evaluated at the two different locations, and the group analysis of the F_2:5 generation indicated that there was a significant genotype × environment interaction. Of the 105 polymorphic SSRs evaluated, 91 mapped to 12 linkage groups with an estimated map size of 1,303.7 cM. Six significant QTLs were detected in both environments, and the percentage of the phenotypic variation that was explained by these loci ranged from 11.54 to 21.63%. As the genetic control was oligogenic, the identification of QTLs should serve as an optimal starting point for the implementation of a selection program.     

An abundance of rare functional variants in 202 drug target genes sequenced in 14,002 people

Rare genetic variants contribute to complex disease risk; however, the abundance of rare variants in human populations remains unknown. We explored this spectrum of variation by sequencing 202 genes encoding drug targets in 14,002 individuals. We find rare variants are abundant (1 every 17 bases) and geographically localized, so that even with large sample sizes, rare variant catalogs will be largely incomplete. We used the observed patterns of variation to estimate population growth parameters, the proportion of variants in a given frequency class that are putatively deleterious, and mutation rates for each gene. We conclude that because of rapid population growth and weak purifying selection, human populations harbor an abundance of rare variants, many of which are deleterious and have relevance to understanding disease risk.     

Behaviour of metolachlor and terbuthylazine in cultivated field lysimeters

An experiment has been carried out in cultivated drainage lysimeters filled with reported soil in order to investigate on the disappearance and mobility of Metolachlor and Terbuthylazine as related to the nitrogen fertilization level. Two experimental units have been compared: in the O-N treatment the soil did not receive N fertilizers during the 7 years previous to the experiment, whereas in the H—N treatment the average application rate of nitrogen during the same period was 220 kg ha^?1 year^?1; a corn crop has been cultivated in the present experiment. The active ingredients have been analysed in the artificial soil profile (from 0 to 40 cm, by 10 cm soil layers) and in leachates. The disappearance rate of Terbuthylazine was affected by nitrogen fertilization level, as the half life resulted about 7 days higher in O—N (21.9 days) treatment than in H—N (14.6 days). On the contrary, N fertilization did not significantly modify the half life of Metolachlor (17.2 and 15.9 days at O—N and H—N, respectively). A N-dealkylated degradation product of Terbuthylazine has been found in the shallow soil layers. The distribution pattern of herbicides content in the soil profile showed that Terbuthylazine was less mobile than Metolachlor. Leachates did not contain Terbuthylazine at all, but amounts of Metolachlor close to the detection limits (25 μg L^?1).     

Occurrence and abundance of carbohydrates and amino compounds in sequentially extracted labile soil organic matter fractions

Purpose

The study aimed to describe the carbohydrates and amino compounds content in soil, the light fraction (LF), the >53 μm particulate organic matter (POM), and the mobile humic acid (MHA) fraction and to find out whether the carbohydrates and amino compounds can be used to explain the origin of SOM fractions.

Materials and methods

Soil samples were collected from two agricultural fields managed under organic farming in southern Italy. The LF, the POM, and the MHA were sequentially extracted from each soil sample then characterized. Seven neutral sugars and 19 amino compounds (amino acids and amino sugars) were determined in each soil sample and its correspondent fractions.

Results and discussion

The MHA contained less carbohydrate than the LF or the POM but its carbohydrates, although dominated by arabinose, were relatively with larger microbial contribution as revealed by the mannose/xylose ratio. The amino compounds were generally less in the LF or the POM than in the MHA, while the fungal (aspartic and serine) and bacterial (alanine and glycine) amino acids were larger in the MHA than in the LF or the POM, underlining the microbial contribution to the MHA. Results from both sites indicated that total carbohydrates content decreased moving from the LF (younger fraction) to the MHA (older fraction), which seems to follow a decomposition continuum of organic matter in the soil-plant system.

Conclusions

The study showed that the MHA is a labile humified fraction of soil C due to its content of carbohydrates and concluded that the content of carbohydrates and amino compounds in the LF, the POM and the MHA can depict the nature of these fractions and their cycling pattern and response to land management.

     

Fermentability of grape must after inhibition with dimethyl dicarbonate (DMDC)

Dimethyl dicarbonate (DMDC) was added to grape must and to synthetic media and results showed that, at 20 degrees C, 150 mg.L(-)(1) DMDC completely inhibited the fermentation of a grape must that was previously inoculated with 10(6) cells.mL(-)(1) Saccharomyces bayanus and Saccharomyces uvarum. Brettanomyces intermedius, Candida guilliermondii, Hansenula jadinii, Hansenula petersonii, Kloeckera apiculata, Pichia membranaefaciens, and Saccharomyces cerevisiae were inhibited by 250 mg.L(-)(1). Candida valida was inhibited in the presence of 350 mg.L(-)(1), whereas Hanseniaspora osmophila, Saccharomycodes ludwigii, Schizosaccharomyces pombe, and Zygosaccharomyces bailii required 400 mg.L(-)(1). Delay of fermentation (but not inhibition) was noted in the presence of 400 mg.L(-)(1) for the following cultures: Brettanomyces anomalus, Hanseniaspora uvarum, Metschnikowia pulcherrima, Schizosaccharomyces japonicus, Torulaspora delbrueckii, and Zygosaccharomyces florentinus. Acetobacter aceti and Lactobacillus sp. were completely inhibited using 1000 and 500 mg.L(-)(1) DMDC, respectively. The fermentation of a grape must inoculated with 10(6) cells.mL(-)(1) of different wine yeasts was delayed for 4 days after the prior addition of 200 mg.L(-)(1) of DMDC; 200 mg.L(-)(1) DMDC did not show any residual inhibitory effect after 12 h, nor did 300 mg.L(-)(1) 24 h after the addition. In cellar experiments, indigenously contaminated grape musts (with and without skins) showed a delay in fermentation of 48 h after the addition of only 50 mg.L(-)(1) DMDC. The possibility of using DMDC (as pure grade as commercially available) in grape must as a disinfectant for the decontamination of musts indigenously contaminated with wild yeast should be considered seriously, despite its apparent low solubility in water.     

Differentiation of extractive and synthetic salicin. The 2H aromatic pattern of natural 2-hydroxybenzyl alcohol

The natural abundance deuterium NMR characterization of four commercially available samples (Kahlbaum, Aldrich, Fluka, and Extrasynthese) of salicin 1 in comparison with two extractive samples from Salix humboldiana and Salix purpurea L. and with a synthetic material, performed on the pentaacetate derivative 2 and on diacetyl salicyl alcohol 4, is reported. Product 2 from S. humboldiana and the sample from salicin Kahlbaum show mean (D/H)aromatic values of 117 and 121 ppm, whereas, for the remaining, values of 146, 154, 153, and 150 ppm are observed, thus suggesting that salicin Kahlbaum is from extractive origin. The (D/H) values at positions 5' and 6' of the sugar moiety suggest a hypothesis on the origin of the glucose residue discriminating between those deriving from C3 or C4 plants. The analysis of 4, obtained from 3, formed in the beta-glucosidase hydrolysis of salicin 1, reveals in the natural samples from S. purpurea and from Kahlbaum the trend (D/H)4(para) > (DH)3(meta) approximately (D/H)5(meta) > (D/H)6(ortho), the first example of deuterium pattern of an ortho-oxygen-substituted phenylpropanoid. The three samples derived from commercial 1 (Aldrich, Fluka, and Extrasynthese) and the synthetic sample show almost identical deuterium content at positions 4 and 6 (around 153 ppm), whereas for the two meta positions (D/H)3 > (D/H)5 (ca. 162 and 140 ppm, respectively). Product 4, obtained from 3 submitted to acid-catalyzed deuteration, shows different deuterium incorporations in the two meta positions (which are ortho/para to the activating phenolic hydroxyl group), suggesting that possibly the deuterium abundance at the two meta positions may be affected by exchange phenomena with the medium.     

Quantitative characterization of flavonoid compounds in Rooibos tea (Aspalathus linearis) by LC-UV/DAD

Rooibos tea originates from the leaves and stems of the indigenous South African plant Aspalathus linearis. It has gained much attention for clinical purposes in the case of nervous tension, allergies (dermatitis), and various indigestive problems. Recently, antioxidative activity was also attributed to the tea on the basis of its flavonoid content. Therefore, an HPLC method using a C(18) reversed phase column was developed for the assay of 10 flavonoids in aqueous and methanolic infusions. Main compounds determined were the dihydrochalcone aspalthin, rutin, and orientin, and their content was in the range of 1.0 to 1.3 mg/g. The identity of detected flavonoids was confirmed by comparing their retention times and UV and MS spectra with those of corresponding standards. In addition, the MS analysis showed evidence of the presence of other compounds such as nothofagin, dihydroisoorientin, and dihydroorientin.     

Aggregation of casein micelles by interactions with chitosans: a study by Monte Carlo simulations

Recently, it was found that the addition of chitosan, a cationic polymer, to whole or skim milk produces the destabilization and coagulation of casein micelles which takes place without modifications in the milk pH or in the stability of most of the whey proteins. In the present work, Monte Carlo simulations are employed to show that the phase separation of casein micelles induced by chitosan can be explained by a depletion mechanism, where an effective attraction between the casein micelles is induced by the presence of chitosan molecules. This interaction is described on the basis of Vrij's model, where the depletion of polymer from the gap between neighboring casein micelles originates an effective attractive interaction that leads to a phase transition. This model, that considers volume restriction effects, accounts for several qualitative and even quantitative aspects of the experimental data for the coagulation of casein through chitosan addition.     

Activity and stability of urease-hydroxyapatite and urease-hydroxyapatite-humic acid complexes

In agricultural calcareous soils, hydroxyapatite (APA) may well represent an important support for urease immobilisation and could be present in both mineral and organo-mineral complexes. In this paper we studied the formation of APA-urease-humic acid (HA) complexes after the addition of urease either before or after HAs. We then proceeded to evaluate the role of HAs on the activity and stability of the complexes as compared to the APA-urease complexes and free urease. When increasing amounts of HAs were added after urease, they did not affect the activity of the enzymes that had already adsorbed onto the complexes. On the contrary, adding the same amount of HA before the enzyme caused a significant reduction in the amount of enzyme adsorbed. However, when urease adsorption onto the APA-HA complexes was carried out in the presence of NaCl, the enzyme activity of the complexes increased sharply to 86% of the initial activity. The immobilisation of the enzyme on the support increased urease stability against pronase treatment as well as directly in soil over time. The inhibition of urease activity by Cu ²⁺was reduced by urease immobilisation. However, the presence of HA did not alter the stabilisation capability of APA when alone.     

Metabolism of stevioside and rebaudioside A from Stevia rebaudiana extracts by human microflora

Stevia rebaudiana standardized extracts (SSEs) are used as natural sweeteners or dietary supplements in different countries for their content of stevioside or rebaudioside A. These compounds possess up to 250 times the sweetness intensity of sucrose, and they are noncaloric and noncariogenic sweeteners. The aim of this study was to investigate the in vitro transformation of stevioside and rebaudioside A after incubation with human microflora, the influence of these sweeteners on human microbial fecal community and which specific groups metabolize preferentially stevioside and rebaudioside A. The experiments were carried out under strict anaerobic conditions in batch cultures inoculated with mixed fecal bacteria from volunteers. The hydrolysis was monitored by HPLC coupled to photodiode array and mass spectrometric detectors. Isolated bacterial strains from fecal materials incubated in selective broths were added to stevioside and rebaudioside A. These sweeteners were completely hydrolyzed to their aglycon steviol in 10 and 24 h, respectively. Interestingly, the human intestinal microflora was not able to degrade steviol. Furthermore, stevioside and rebaudioside A did not significantly influence the composition of fecal cultures; among the selected intestinal groups, bacteroides were the most efficient in hydrolyzing Stevia sweeteners to steviol.