Chemical characterization of red wine grape (Vitis vinifera and Vitis interspecific hybrids) and pomace phenolic extracts and their biological activity against Streptococcus mutans

Grapes are rich sources of potentially bioactive polyphenols. However, the phenolic content is variable depending on grape variety, and may be modified during vinification. In this study, we examined the chemical composition and biological activity of phenolic extracts prepared from several red wine grape varieties and their fermented byproduct of winemaking (pomace) on some of the virulence properties of Streptococcus mutans a well-known dental pathogen. Grape phenolic extracts were obtained from Vitis vinifera varieties Cabernet Franc and Pinot Noir and Vitis interspecific hybrid varieties Baco Noir and Noiret. The anthocyanins and flavan-3-ols content were highly variable depending on grape variety and type of extract (whole fruit vs fermented pomace). Nevertheless, all grape phenolic extracts remarkably inhibited glucosyltransferases B and C (70-85% inhibition) at concentrations as low as 62.5 microg/mL (P < 0.01). Furthermore, the glycolytic pH-drop by S. mutans cells was inhibited by the grape extracts without affecting the bacterial viability; an effect that can be attributed to partial inhibition of F-ATPase activity (30-65% inhibition at 125 microg/mL; P < 0.01). The biological activity of fermented pomace was either as effective as or significantly better than whole fruit grape extracts. The results showed that grape phenolic extracts, especially from pomace, are highly effective against specific virulence traits of S. mutans despite major differences in their phenolic content.     

Interaction of arbuscular mycorrhizal fungi and rhizobia: Effects on flax yield in spoil‐bank clay

This study focused on the application of native strains of arbuscular mycorrhizal fungi (AMF) and Sinorhizobium in effective crop production during reclamation of coal‐mine spoil banks. Two greenhouse experiments were conducted in spoil‐bank clay with a low dose of organic amendment to determine whether the microbial inoculation improves growth and utility qualities of two cultivars of Linum usitatissimum L. (oil and fiber flax). Inoculation with two native AMF isolates (Glomus mosseae, G. intraradices, and their mixture) significantly increased growth and shoot phosphorus (P) concentration of both flax cultivars. Inoculated fiber flax plants produced fivefold more fibers than the uninoculated ones. In oil flax, mycorrhizal inoculation significantly but quantitatively to a minor degree decreased the concentration of nonsaturated fatty acids in the seed oil. A mixture of five native Sinorhizobium sp. strains supported growth and P uptake of oil flax only in the absence of AMF. However, these beneficial effects of the bacteria were significantly lower as compared to AMF. No synergic action of Sinorhizobium strains and AMF was observed, and their interactions were often even antagonistic. Inoculation with AMF significantly decreased population density of Sinorhizobium in the soil. These results suggest that a careful selection of suitable bacterial strains is necessary to provide effective AMF combinations and maximize flax‐growth support.     

Using humic products as amendments to restore Zn and Pb polluted soil: a case study using rapid screening phytotest endpoint

Purpose

Heavy metal contamination is a priority issue affecting millions of hectares of soil throughout the world. One of the most promising, environmentally friendly, and cost-effective approaches to restore polluted soils could be applying organic amendments. We investigated the remediation potential of three types of humic products with regard to their effect on the bioavailability of Pb and Zn, content of nutrients, and the ability to mitigate acute phytotoxicity in contaminated soil.

Materials and methods

Spodosol samples were spiked with Pb (550 mg kg^?1) and Zn (880 mg kg^?1). Then, two different commercial humic products (from peat and lignosulfonate) and natural humic acids (from brown oxidized coal) were added in two doses to reach an equal content of carbon: a 10% increment and a 30% increment of the initial total organic carbon in the soil. After 30 days, the content of metals and nutrients (S, K, Na, Ca, Mn, P) was determined by the sequential extraction (i?H₂O, ii?NH₄COOH pH 4.8, iii–CH₃COOH). The effect of humic products on heavy metals bioavailability was evaluated using the calculated partition indexes. Seed germination and root elongation of Sinapis alba were also determined. Chemical and biochemical variables were aggregated by the principal component analysis.

Results and discussion

Humic products reduced the amount of bioavailable fractions of Pb and Zn in soils. The partition index, which quantitatively describes bioavailable fractions of the Zn and Pb in the soil, was 28–49% lower than in the spiked (Pb+Zn) control. The inhibition of root elongation and seed germination of mustard by Zn and Pb was significantly mitigated by humic products; in the soil test, the root length and seed germination were up to 36–87% higher than those of the Pb+Zn control and did not differ from those in the non-amended treatments. This effect may have been associated with the structural differences (H/C and O/C ratio) and content of nutrients (Na and K) in humic products.

Conclusions

Commercial humic products used in poor multi-contaminated soils can maintain plant growth by improving nutrient status due to heavy metals immobilization and can be a promising approach to remediate the soil contaminated with heavy metals at extremely high concentrations.

     

Major genes for resistance to beet necrotic yellow vein virus (BNYVV) in Beta vulgaris

Summary Inheritance of resistance to beet necrotic yellow vein virus (BNYVV) was studied in segregating F2 and backcross families obtained from crosses between resistant plants of the sugar beet selection Holly-1-4 or the wild beet accession Beta vulgaris subsp. maritima WB42 and susceptible parents. Greenhouse tests were carried out, in which seedlings were grown in a mixture of sand and infested soil. Virus concentrations of BNYVV in the rootlets were estimated by ELISA. To discriminate resistant and susceptible plants, mixtures of normal distributions were fitted to log₁₀ virus concentrations, estimated for segregating F1, F2 and BC populations of both accessions. The hypothesis that Holly-1-4 contained one single dominant major gene was accepted. For WB42, results fitted with the hypotheses that resistance was based on either one (or more) dominant major gene(s) showing distorted segregation, or two complementary dominant genes, which are both required for resistance. Resistance from WB42 appeared to be more effective against BNYVV than resistance from Holly-1-4.This research was carried out as part of a PhD study at the Graduate School Experimental Plant Sciences (EPS), Department of Virology, Wageningen, The Netherlands     

cDNA clone of a putative peanut (Arachis hypogaea L.) trypsin inhibitor has homology with peanut allergens Ara h 3 and Ara h 4

Trypsin inhibitors are pathogenesis-related (PR) proteins, which play an important role in the plant defense mechanism against insects and pathogens. Peanut trypsin inhibitors are low molecular mass seed storage proteins. Like peanut allergens, they are stable to acid and heat, resistant to digestion, and can have a negative impact on human health. In peanut, five Bowman-Birk trypsin inhibitors (BBTI) have been isolated and amino acid sequences published. However, to date, no peanut BBTI sequence is available at both the cDNA and the genomic levels. The objectives of this investigation were (i) to synthesize degenerate oligonucleotides based on conserved regions of published amino acid sequences of BBTI, BII, and BIII; (ii) to isolate, sequence, and analyze at least one positive peanut trypsin inhibitor cDNA clone using the synthesized (32)P-labeled oligonucleotides as probes; and (iii) to determine its trypsin inhibitory activity. Thirty-two degenerate oligonucleotides DNA primers of 24 nucleotides each were synthesized based on the published amino acid sequences of peanut BBTI, and two were selected as probes to screen a peanut Lambda gt 11 cDNA library. Three putative positive clones were isolated, purified, and subcloned, and one was sequenced. Sequence analysis revealed a partial cDNA clone of 643 bp with a start codon. This clone shares 93 and 96% nucleotide sequence homology with peanut allergens Ara h 3 and Ara h 4 cDNA clones, respectively. A trypsin inhibitor assay revealed that peanut allergen Ara h 3 has a trypsin inhibitory activity of 11 238 TIA/mg protein. We concluded that peanut allergen Ara h 3 may also function as a trypsin inhibitor.     

Structure of DNMT1-DNA complex reveals a role for autoinhibition in maintenance DNA methylation

Maintenance of genomic methylation patterns is mediated primarily by DNA methyltransferase-1 (DNMT1). We have solved structures of mouse and human DNMT1 composed of CXXC, tandem bromo-adjacent homology (BAH1/2), and methyltransferase domains bound to DNA-containing unmethylated CpG sites. The CXXC specifically binds to unmethylated CpG dinucleotide and positions the CXXC-BAH1 linker between the DNA and the active site of DNMT1, preventing de novo methylation. In addition, a loop projecting from BAH2 interacts with the target recognition domain (TRD) of the methyltransferase, stabilizing the TRD in a retracted position and preventing it from inserting into the DNA major groove. Our studies identify an autoinhibitory mechanism, in which unmethylated CpG dinucleotides are occluded from the active site to ensure that only hemimethylated CpG dinucleotides undergo methylation.     

Ethylene modulates stem cell division in the Arabidopsis thaliana root

The construction of multicellular organisms depends on stem cells-cells that can both regenerate and produce daughter cells that undergo differentiation. Here, we show that the gaseous messenger ethylene modulates cell division in the cells of the quiescent center, which act as a source of stem cells in the seedling root. The cells formed through these ethylene-induced divisions express quiescent center-specific genes and can repress differentiation of surrounding initial cells, showing that quiescence is not required for these cells to signal to adjacent stem cells. We propose that ethylene is part of a signaling pathway that modulates cell division in the quiescent center in the stem cell niche during the postembryonic development of the root system.     

Constraints on neon and argon isotopic fractionation in solar wind

To evaluate the isotopic composition of the solar nebula from which the planets formed, the relation between isotopes measured in the solar wind and on the Sun's surface needs to be known. The Genesis Discovery mission returned independent samples of three types of solar wind produced by different solar processes that provide a check on possible isotopic variations, or fractionation, between the solar-wind and solar-surface material. At a high level of precision, we observed no significant inter-regime differences in 20Ne/22Ne or 36Ar/38Ar values. For 20Ne/22Ne, the difference between low- and high-speed wind components is 0.24 +/- 0.37%; for 36Ar/38Ar, it is 0.11 +/- 0.26%. Our measured 36Ar/38Ar ratio in the solar wind of 5.501 +/- 0.005 is 3.42 +/- 0.09% higher than that of the terrestrial atmosphere, which may reflect atmospheric losses early in Earth's history.     

Single-cell mass cytometry of differential immune and drug responses across a human hematopoietic continuum

Flow cytometry is an essential tool for dissecting the functional complexity of hematopoiesis. We used single-cell "mass cytometry" to examine healthy human bone marrow, measuring 34 parameters simultaneously in single cells (binding of 31 antibodies, viability, DNA content, and relative cell size). The signaling behavior of cell subsets spanning a defined hematopoietic hierarchy was monitored with 18 simultaneous markers of functional signaling states perturbed by a set of ex vivo stimuli and inhibitors. The data set allowed for an algorithmically driven assembly of related cell types defined by surface antigen expression, providing a superimposable map of cell signaling responses in combination with drug inhibition. Visualized in this manner, the analysis revealed previously unappreciated instances of both precise signaling responses that were bounded within conventionally defined cell subsets and more continuous phosphorylation responses that crossed cell population boundaries in unexpected manners yet tracked closely with cellular phenotype. Collectively, such single-cell analyses provide system-wide views of immune signaling in healthy human hematopoiesis, against which drug action and disease can be compared for mechanistic studies and pharmacologic intervention.