[Show abstract][Hide abstract] ABSTRACT: Somatic embryogenesis is a powerful biotechnological tool for the mass production of economically important cultivars. Due to the cellular totipotency of plants, somatic cells under appropriate conditions are able to develop a complete functional embryo. During the induction of somatic embryogenesis, there are different factors involved in the success or failure of the somatic embryogenesis response. Among these factors, the origin of the explant, the culture medium and the in vitro environmental conditions have been the most studied. However, the secretion of molecules into the media has not been fully addressed. We found that the somatic embryogenesis of Coffea canephora , a highly direct embryogenic species, is disrupted by the metabolites secreted from C . arabica , a poorly direct embryogenic species. These metabolites also affect DNA methylation. Our results show that the abundance of two major phenolic compounds, caffeine and ch
PLoS ONE 06/2015; 10(6-6):e0126414. DOI:10.1371/journal.pone.0126414 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ensuring the efficient uptake of micronutrients and protection against toxicity of non-essential elements are the two important issues in trace element research for human nutrition. Since the uptake, in vivo utilization, specific biological functions or toxic effects of a given element are subject to its actual physicochemical form, food speciation analysis has received much attention over the past few decades. Different analytical schemes have been developed, depending on elements/species of interest, their physicochemical properties, total concentrations, chemical composition of the sample and the specific goal of the analysis. In this chapter, the methodological aspects of food speciation analysis are presented, including the description of different fractionation schemes, non-chromatographic approaches and hyphenated techniques. Studies evaluating the effect of food elaboration and gastrointestinal ingestion have also been considered. The role of atomic spectrometry techniques as the primary detection tools in analysis of known species/forms is highlighted and the applications of structure-characterizing techniques for species confirmation/identification in innovating speciation studies are also mentioned. Representative examples from the recent literature are reviewed in order to present the trends in sample pretreatment, species separation and quatification. New challenges due to the expanding knowledge of trace elements in human nutrition, the production of selenium-fortified prducts, the use of transgenic food and the presence of metal/metalloid-based nanomaterials have been featured. Finally, an outlook on the approaches to quantification and quality control is briefly presented.
[Show abstract][Hide abstract] ABSTRACT: Three α-ketoaldehydes, potentially present in high fructose agave syrups (HFASs) as intermediates of the Maillard reaction, were determined. A previously reported HPLC-FLD procedure based on pre-column derivatisation with 4-methoxy-o-phenylenediamine was adopted, yielding the method quantification limits 0.11mg/kg, 0.10mg/kg, 0.09mg/kg for glyoxal, methylglyoxal (MGo) and diacetyl, respectively. The obtained results revealed high concentrations of methylglyoxal in HFASs (average 102±91mg/kg, range 15.6-315mg/kg) as compared to commercial Mexican bee honeys or corn syrups. Hydrogen peroxide was generated in all HFASs upon dilution, yet to less extent than in bee honeys. HFASs presented bacteriostatic activity against Bacillus subtilis and Escherichia coli; catalase addition had minimum effect on the assay results in syrups with elevated MGo. Principal component analysis revealed direct association between growth inhibition and MGo. It is concluded that elevated concentration of MGo in HFASs is at least in part responsible for their non-peroxide bacteriostatic activity.
[Show abstract][Hide abstract] ABSTRACT: A straightforward synthetic protocol to directly incorporate stabilized 1,3-dicarbonyl C nucleophiles to the meso position of BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is reported. Soft nucleophiles generated by deprotonation of 1,3-dicarbonyl derivatives smoothly displace the 8-methylthio group from 8-(methylthio)BODIPY analogues in the presence of CuI thiophenecarboxylate in stoichiometric amounts at room temperature. Seven highly fluorescent new derivatives are prepared with varying yields (20–92 %) in short reaction times (5–30 min). The excellent photophysical properties of the new dyes allow focusing on applications never analyzed before for BODIPYs substituted with stabilized C nucleophiles such as pH sensors and lasers in liquid and solid state, highlighting the relevance of the synthetic protocol described in the present work. The attainment of these dyes, with strong UV absorption and highly efficient and stable laser emission in the green spectral region, concerns to one of the greatest challenges in the ongoing development of advanced photonic materials with relevant applications. In fact, organic dyes with emission in the green are the only ones that allow, by frequency-doubling processes, the generation of tunable ultraviolet (250-350 nm) radiation, with ultra-short pulses.
Chemistry - A European Journal 12/2014; 21(4). DOI:10.1002/chem.201405233 · 5.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Experimental evidence indicates that diabetic patients and individuals with impaired copper homeostasis could be at risk of molybdenum toxicity. A self-administered food frequency questionnaire revealed that in central Mexico, diabetic patients with severe complications tend to consume beans more often than individuals with less advanced disease. Four varieties of Phaseolus vulgaris were comparatively evaluated as the dietary sources of two elements; the results showed molybdenum concentration decreasing in the order peruvian > pinto > mayflower > black, whereas for copper, the order was peruvian > pinto ∼ black > mayflower. The two elements were determined in pre-soaking water, cooked legumes, and broth obtained in cooking procedure; an in vitro gut model was also applied to assess potentially bioavailable fraction of both elements in cooked beans. The results indicated that the black variety would be the healthiest bean choice for diabetic patients and individuals susceptible to Mo toxicity. Relatively low total molybdenum was found in this variety (2.9 ± 1.4 versus 4.3-10.9 μg g(-1) in other types), element availability was also low (15 % in supernatant from enzymolysis, 24.9 % in combined broth + supernatant fractions), and the molar ratio of Cu/Mo was the highest among four types (41, versus Cu/Mo <10 in peruvian, pinto, or mayflower). Considering peruvian and pinto beans, broth elimination would help to lower molybdenum intake with marginal effect on Cu/Mo molar ratio. This recommendation would be especially important for peruvian variety, which provided 1090, 803, and 197 μg day(-1) of molybdenum in raw grains, broth + supernatant, and supernatant, respectively (based on 100-g portion), exceeding the recommended daily allowance of 45 μg day(-1).
Biological Trace Element Research 11/2014; 163(1-2). DOI:10.1007/s12011-014-0191-5 · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The ability of human serum albumin to capture unbound copper under different clinical conditions is an important variable potentially affecting homeostasis of this element. Here, we propose a simple procedure based on size-exclusion chromatography with on-line UV and nitrogen microwave-plasma atomic-emission spectrometry (MP-AES) for quantitative evaluation of Cu(II) binding to HSA upon its glycation in vitro. The Cu-to-protein molar ratio for non-glycated albumin was 0.98 ± 0.09; for HSA modified with glyoxal (GO), methylglyoxal (MGO), oxoacetic acid (GA), and glucose (Glc), the ratios were 1.30 ± 0.22, 0.72 ± 0.14, 0.50 ± 0.06, and 0.95 ± 0.12, respectively. The results were confirmed by using ICP-MS as an alternative detection system. A reduced ability of glycated protein to coordinate Cu(II) was associated with alteration of the N-terminal metal-binding site during incubation with MGO and GA. In contrast, glycation with GO seemed to generate new binding sites as a result of tertiary structural changes in HSA. Capillary reversed-phase liquid chromatography with electrospray-ionization quadrupole-time-of-flight tandem mass spectrometry enabled detection and identification of Cu(II) coordinated to the N-terminal metal-binding site (Cu(II)–DAHK) in all tryptic digests analyzed. This is the first report confirming Cu(II)–DAHK species in HSA by means of high-resolution tandem mass spectrometry, and the first report on the use of MP-AES in combination with chromatographic separation.
General scheme designed to study Cu(II) binding to glycated versus non-glycated albumin and MPAESinstrumentation used
[Show abstract][Hide abstract] ABSTRACT: In this work, the sorption of pentachlorophenol (PCP) by non-viable biomass of Rhizopus oryzae ENHE was evaluated. The kinetics and isotherm studies were performed at pH 5.0, 6.0, and 8.0. The point of zero charge of the biomass was determined; this value allowed us to explain the changes of pH during sorption studies. The analyzed experimental kinetic data revealed that Ho's model adjusted better to the experimental data than Lagergren's model. PCP sorption was fast; an equilibrium sorption time was reached within 30 min, regardless of pH. PCP sorption at pH 5.0 and 6.0 was better described by the Freundlich isotherm than by the Langmuir isotherm. In contrast, at pH 8.0, the Langmuir isotherm describes better the PCP sorption. Sorption data showed that at pH 5.0 and 6.0, the sorption capacity of PCP was higher than at pH 8.0. Sorption of PCP by the fungal biomass occurred spontaneously; it was endothermic and due to physical sorption. Finally, FT-IR analysis of the dried biomass indicated that amino and hydroxyl groups were involved in the sorption of PCP. This work is one of the few reporting the effect of pH and temperature on the sorption of PCP by microbial biomass from a filamentous fungus belonging to the genus Rhizopus.
Water Air and Soil Pollution 05/2014; 225(5). DOI:10.1007/s11270-014-1947-4 · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tequila is elaborated from Agave tequilana Weber blue variety and it is commercialized at different stages of aging. Chemical composition of this product has often been addressed; however, data on phenolic compounds are scarce. In this work, a high-performance liquid chromatography–electrospray ionization-ion trap mass spectrometry (HPLC–ESI-ITMS) procedure has been established for the determination of 34 small phenolic compounds. The combination of suitable separation conditions with extraction of chromatograms at individual m/z values has enabled for total analysis run of 17 min (11 min separation plus 6 min column cleaning/equilibration) with the detection limits in the range 1.28–75.0 μg l−1 (0.07–6.1 pmol on-column). Commercial tequilas analyzed included 6 white, 12 rested, and 4 aged. The following acids were found and quantified: gallic, procatechuic, 4-hydroxybenzoic, vanillic, syringic, homovanillic, 3-hydroxybenzoic, ferulic, salicylic, and benzoic. The white tequilas contained fewer compounds and lower total phenolics concentrations (range 36–408 μg l−1) as compared to the rested and aged liquors (515–4,296 and 2,048–3,249 μg l−1, respectively). In the latter products, syringic, vanillic, procatechuic, and gallic acids were the most abundant, which indicates that maturation in wooden barrels is the main source of small phenolics in tequila. On the other part, homovanillic acid was found in all tequila types (medians for white, rested, and aged products 82, 153, and 162 μg l−1, respectively), suggesting that some phenolics may originate from the raw material or might be formed during liquor elaboration.
[Show abstract][Hide abstract] ABSTRACT: Bioanalytical relevance of glyoxal (Go) and methylglyoxal (MGo) arises from their role as biomarkers of glycation processes and oxidative stress. The third compound of interest in this work is diacetyl (DMGo), a component of different food products and alcoholic beverages and one of the small α-ketoaldehydes previously reported in urine. The original idea for the determination of the above compounds by reversed phase high-performance liquid chromatography (HPLC) with fluorimetric detection was to use 4-methoxy-o-phenylenediamine (4MPD) as a derivatizing reagent and diethylglyoxal (DEGo) as internal standard. Acetonitrile was added to urine for matrix precipitation, and derivatization reaction was carried out in the diluted supernatant at neutral pH (40 °C, 4 h); after acidification, salt-induced phase separation enabled recovery of the obtained quinoxalines in the acetonitrile layer. The separation was achieved within 12 min using a C18 Kinetex column and gradient elution. The calibration detection limits for Go, MGo, and DMGo were 0.46, 0.39, and 0.28 μg/L, respectively. Within-day precision for real-world samples did not exceed 6%. Several urine samples from healthy volunteers, diabetic subjects, and juvenile swimmers were analyzed. The sensitivity of the procedure proposed here enabled detection of differences between analyte concentrations in urine from patients at different clinical or exposure-related conditions.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to investigate the effects of cadmium [Cd(II) as cadmium chloride], selenium [Se(IV) as sodium selenite] and their mixtures on phenolic compounds (PCs) and antioxidant activity (AOx) in Lepidium sativum. The biomass fractions corresponding to free (F1), soluble glycoside-bound (F2) and cell wall ester-bound phenolics (F3) were obtained for each treatment and PCs were screened by gas chromatography (GC-FID); F1 and F2 fractions were also analyzed by liquid chromatography with UV and fluorimetric detection. The treated plants presented different profiles of PCs as compared to controls, specifically in F1 and F2 fractions; the plant response was element-, and concentration-dependent. The cultures challenged with Cd(II) up to 5 mg L−1, presented higher AOx with respect to controls, and this increase was associated with glycoside-bound PCs, whereas for Se(IV) the increase of AOx was less marked and associated with free PCs. Under simultaneous exposure to Cd(II) + Se(IV) (0.5–2.0 mg L−1 each), the AOx values were relatively constant and lower than those found in the presence of Se(IV) or Cd(II) alone, providing further evidence of the protective role of Se(IV) against stress imposed by Cd(II) in this plant species. The evaluation of AOx of individual PCs and the results of principal component analysis enabled to attain several relationships among exposure conditions, antioxidant activity, free- and glycoside-bound phenolic compounds.
Acta Physiologiae Plantarum 01/2014; 35(2). DOI:10.1007/s11738-012-1086-8 · 1.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Arsenic release from the abandoned mines and its fate in a local stream were studied. Physicochemical parameters, metals/metalloids and arsenic species were determined. One of the mine drainages was found as a point source of contamination with 309 μg L(-1) of dissolved arsenic; this concentration declined rapidly to 10.5 μg L(-1) about 2 km downstream. Data analysis confirmed that oxidation of As(III) released from the primary sulfide minerals was favored by the increase of pH and oxidation reduction potential; the results obtained in multivariate approach indicated that self-purification of water was due to association of As(V) with secondary solid phase containing Fe, Mn, Ca.
Bulletin of Environmental Contamination and Toxicology 09/2013; 91(5). DOI:10.1007/s00128-013-1091-7 · 1.26 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Plant cells have the capacity to generate a new plant without egg fertilization by a process known as somatic embryogenesis (SE), in which differentiated somatic cells can form somatic embryos able to generate a functional plant. Although there have been advances in understanding the genetic basis of SE, the epigenetic mechanism that regulates this process is still unknown. Here, we show that the embryogenic development of Coffea canephora proceeds through a crosstalk between DNA methylation and histone modifications during the earliest embryogenic stages of SE. We found that low levels of DNA methylation, histone H3 lysine 9 dimethylation (H3K9me2) and H3K27me3 change according to embryo development. Moreover, the expression of LEAFY COTYLEDON1 (LEC1) and BABY BOOM1 (BBM1) are only observed after SE induction, whereas WUSCHEL-RELATED HOMEOBOX4 (WOX4) decreases its expression during embryo maturation. Using a pharmacological approach, it was found that 5-Azacytidine strongly inhibits the embryogenic response by decreasing both DNA methylation and gene expression of LEC1 and BBM1. Therefore, in order to know whether these genes were epigenetically regulated, we used Chromatin Immunoprecipitation (ChIP) assays. It was found that WOX4 is regulated by the repressive mark H3K9me2, while LEC1 and BBM1 are epigenetically regulated by H3K27me3. We conclude that epigenetic regulation plays an important role during somatic embryogenic development, and a molecular mechanism for SE is proposed.
PLoS ONE 08/2013; 8(8):e72160. DOI:10.1371/journal.pone.0072160 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this work, the effect of cadmium (0-5.0 mg L(-1) as cadmium chloride, Cd(ii)) and selenium (0-2.0 mg L(-1) as sodium selenite, Se(iv)) was studied in Lepidium sativum with specific focus on glyoxal (GO) and methylglyoxal (MGO) and on the cellular distribution of both elements under different exposure conditions. The concentrations of two reactive α-ketoaldehydes present as natural metabolites and as by-products of lipid peroxidation, were increased in plants treated with Cd(ii), providng complementary experimental evidence on element phytotoxicity in garden cress, in terms of oxidative damage. Even though for higher than 1.0 mg L(-1) Se in medium similar adverse effect was found, under simultaneous exposure to both elements the changes in GO and MGO concentrations were clearly attenuated as compared to a single stressor treatment. This effect was accompanied by lower uptake of the two elements, significant decrease of their relative distribution in the fraction containing polar compounds and their increase in fraction corresponding to insoluble cell fragments/components, suggesting that the direct in vivo interaction between two element forms might be involved in the favorable effects of simultaneous treatment with Cd(ii) + Se(iv). The fluorescence spectra obtained for biomass extracts corresponding to different exposure conditions suggested possible in vivo formation of CdSe quantum dots; however further studies are needed for ultimate identification and characterization of such nanoparticulate species.
[Show abstract][Hide abstract] ABSTRACT: Large amounts of phosphate fertilizers utilized in agriculture and their relatively poor efficiency are of high ecological and economic concern. Therefore, transgenic plants capable of metabolizing phosphite are being engineered. In support of this biotechnological task, analytical speciation of phosphorus in biological tissues is required. In this study, plant extracts were analyzed by liquid chromatography - inductively coupled plasma mass spectrometry at m/z of elemental phosphorus and phosphorus oxide ions. Using polymeric-based anion exchange column and millimolar concentration of nitric acid in potassium phthalate mobile phase (pH 2.5), phosphite and phosphate ions were baseline resolved with retention times 6.95 ± 0.03 min and 7.90 ± 0.03 min and with total chromatographic run time 10 min. The detection limits were 1.58 μgP L-1 and 1.74 μgP L-1 at m/z 47, as compared to 2.18 μgP L-1 and 2.04 μgP L-1 at m/z 31, respectively. The results obtained in real world samples for the two detection modes were in good agreement, yet signal acquisition at m/z 47 enabled for better precision without collision/reaction cell (RSD below 2%) as compared to RSD around 4% obtained at m/z 31 while using He pressurized cell (3.5 mL min-1).
Journal of Agricultural and Food Chemistry 06/2013; 61(27). DOI:10.1021/jf4012278 · 2.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present work, application of the previously established reversed-phase liquid chromatography procedure based on fluorescent labeling of cytosine and methylcytosine moieties with 2-bromoacetophenone (HPLC-FLD) is presented for simultaneous evaluation of global DNA and total RNA methylation at cytosine carbon 5. The need for such analysis was comprehended from the recent advances in the field of epigenetics that highlight the importance of non-coding RNAs in DNA methylation and suggest that RNA methylation might play a similar role in the modulation of genetic information, as previously demonstrated for DNA. In order to adopt HPLC-FLD procedure for DNA and RNA methylation analysis in a single biomass extract, two extraction procedures with different selectivity toward nucleic acids were examined, and a simplified calibration was designed allowing for evaluation of methylation percentage based on the ratio of chromatographic peak areas: cytidine/5-methylcytidine for RNA and 2´-deoxycytidine/5-methyl-2'-deoxycytidine for DNA. As a proof of concept, global DNA and total RNA methylation were determined in Lepidium sativum hydroponically grown in the presence of different Cd(II) or Se(IV) concentrations, expecting that plant exposure to abiotic stress might affect not only global DNA but also total RNA methylation. The results obtained showed the increase of DNA methylation in the treated plants up to concentration levels 2 mg L(-1) Cd and 1 mg L(-1) Se in the growth medium. For higher stressors' concentration, global DNA methylation tended to decrease. Most importantly, an inverse correlation was found between DNA and RNA methylation levels (r = -0.6788, p = 0.031), calling for further studies of this particular modification of nucleic acids in epigenetic context.