Purification and Characterization of a NADPH-Dependent Aldehyde Reductase from Mung Bean That Detoxifies Eutypine, a Toxin from Eutypa lata1

Eutypine (4-hydroxy-3-[3-methyl-3-butene-1-ynyl] benzaldehyde) is a toxin produced by Eutypa lata, the causal agent of eutypa dieback in the grapevine (Vitis vinifera). Eutypine is enzymatically converted by numerous plant tissues into eutypinol (4-hydroxy-3-[3-methyl-3-butene-1-ynyl] benzyl alcohol), a metabolite that is nontoxic to grapevine. We report a four-step procedure for the purification to apparent electrophoretic homogeneity of a eutypine-reducing enzyme (ERE) from etiolated mung bean (Vigna radiata) hypocotyls. The purified protein is a monomer of 36 kD, uses NADPH as a cofactor, and exhibits a Km value of 6.3 μm for eutypine and a high affinity for 3- and 4-nitro-benzaldehyde. The enzyme failed to catalyze the reverse reaction using eutypinol as a substrate. ERE detoxifies eutypine efficiently over a pH range from 6.2 to 7.5. These data strongly suggest that ERE is an aldehyde reductase that could probably be classified into the aldo-keto reductase superfamily. We discuss the possible role of this enzyme in eutypine detoxification.

Differential Responses of Abaxial and Adaxial Guard Cells of Broad Bean to Abscisic Acid and Calcium1

Regulation by abscisic acid (ABA) and Ca2+ of broad bean (Vicia faba) abaxial and adaxial guard cell movements and inward K+ currents were compared. One millimolar Ca2+ in the bathing medium inhibited abaxial stomatal opening by 60% but only inhibited adaxial stomatal opening by 15%. The addition of 1 μm ABA in the bathing medium resulted in 80% inhibition of abaxial but only 45% inhibition of adaxial stomatal opening. Similarly, ABA and Ca2+ each stimulated greater abaxial stomatal closure than adaxial stomatal closure. Whole-cell patch-clamp results showed that the inward K+ currents of abaxial guard cells were inhibited by 60% (−180 mV) in the presence of 1.5 μm Ca2+ in the cytoplasm, whereas the inward K+ currents of adaxial guard cells were not affected at all by the same treatment. Although 1 μm ABA in the cytoplasm inhibited the inward K+ currents to a similar extent for both abaxial and adaxial guard cells, the former were more sensitive to ABA applied externally. These results suggest that the abaxial stomata are more sensitive to Ca2+ and ABA than adaxial stomata in regard to stomatal opening and closing processes and that the regulation of the inward K+ currents by ABA may not proceed via a Ca2+-signaling pathway in adaxial guard cells. Therefore, there may be different pathways for ABA- and Ca2+-mediated signal transduction in abaxial and adaxial guard cells.

Light and Excess Manganese1 : Implications for Oxidative Stress in Common Bean

The effect of light intensity on antioxidants, antioxidant enzymes, and chlorophyll content was studied in common bean (Phaseolus vulgaris L.) exposed to excess Mn. Leaves of bean genotypes contrasting in Mn tolerance were exposed to two different light intensities and to excess Mn; light was controlled by shading a leaflet with filter paper. After 5 d of Mn treatment ascorbate was depleted by 45% in leaves of the Mn-sensitive genotype ZPV-292 and by 20% in the Mn-tolerant genotype CALIMA. Nonprotein sulfhydryl groups and glutathione reductase were not affected by Mn or light treatment. Ten days of Mn-toxicity stress increased leaf ascorbate peroxidase activity of cv ZPV-292 by 78% in low light and by 235% in high light, and superoxide dismutase activity followed a similar trend. Increases of ascorbate peroxidase and superoxide dismutase activity observed in cv CALIMA were lower than those observed in the susceptible cv ZPV-292. The cv CALIMA had less ascorbate oxidation under excess Mn-toxicity stress. Depletion of ascorbate occurred before the onset of chlorosis in Mn-stressed plants, especially in cv ZPV-292. Lipid peroxidation was not detected in floating leaf discs of mature leaves exposed to excess Mn. Our results suggest that Mn toxicity may be mediated by oxidative stress, and that the tolerant genotype may maintain higher ascorbate levels under stress than the sensitive genotype.

Comparative Biochemistry of the Oxidative Burst Produced by Rose and French Bean Cells Reveals Two Distinct Mechanisms1

Cultured cells of rose (Rosa damascena) treated with an elicitor derived from Phytophthora spp. and suspension-cultured cells of French bean (Phaseolus vulgaris) treated with an elicitor derived from the cell walls of Colletotrichum lindemuthianum both produced H2O2. It has been hypothesized that in rose cells H2O2 is produced by a plasma membrane NAD(P)H oxidase (superoxide synthase), whereas in bean cells H2O2 is derived directly from cell wall peroxidases following extracellular alkalinization and the appearance of a reductant. In the rose/Phytophthora spp. system treated with N,N-diethyldithiocarbamate, superoxide was detected by a N,N′-dimethyl-9,9′-biacridium dinitrate-dependent chemiluminescence; in contrast, in the bean/C. lindemuthianum system, no superoxide was detected, with or without N,N-diethyldithiocarbamate. When rose cells were washed free of medium (containing cell wall peroxidase) and then treated with Phytophthora spp. elicitor, they accumulated a higher maximum concentration of H2O2 than when treated without the washing procedure. In contrast, a washing treatment reduced the H2O2 accumulated by French bean cells treated with C. lindemuthianum elicitor. Rose cells produced reductant capable of stimulating horseradish (Armoracia lapathifolia) peroxidase to form H2O2 but did not have a peroxidase capable of forming H2O2 in the presence of reductant. Rose and French bean cells thus appear to be responding by different mechanisms to generate the oxidative burst.

The role of haustoria in sugar supply during infection of broad bean by the rust fungus Uromyces fabae

Biotrophic plant pathogenic fungi differentiate specialized infection structures within the living cells of their host plants. These haustoria have been linked to nutrient uptake ever since their discovery. We have for the first time to our knowledge shown that the flow of sugars from the host Vicia faba to the rust fungus Uromyces fabae seems to occur largely through the haustorial complex. One of the most abundantly expressed genes in rust haustoria, the expression of which is negligible in other fungal structures, codes for a hexose transporter. Functional expression of the gene termed HXT1 in Saccharomyces cerevisiae and Xenopus laevis oocytes assigned a substrate specificity for d-glucose and d-fructose and indicated a proton symport mechanism. Abs against HXT1p exclusively labeled haustoria in immunofluorescence microscopy and the haustorial plasma membrane in electron microscopy. These results suggest that the fungus concentrates this transporter in haustoria to take advantage of a specialized compartment of the haustorial complex. The extrahaustorial matrix, delimited by the plasma membranes of both host and parasite, constitutes a newly formed apoplastic compartment with qualities distinct from those of the bulk apoplast. This organization might facilitate the competition of the parasite with natural sink organs of the host.

Mexican papita viroid: putative ancestor of crop viroids.

The potato spindle tuber disease was first observed early in the 20th century in the northeastern United States and shown, in 1971, to be incited by a viroid, potato spindle tuber viroid (PSTVd). No wild-plant PSTVd reservoirs have been identified; thus, the initial source of PSTVd infecting potatoes has remained a mystery. Several variants of a novel viroid, designated Mexican papita viroid (MPVd), have now been isolated from Solanum cardiophyllum Lindl. (papita güera, cimantli) plants growing wild in the Mexican state of Aguascalientes. MPVd's nucleotide sequence is most closely related to those of the tomato planta macho viroid (TPMVd) and PSTVd. From TPMVd, MPVd may be distinguished on the basis of biological properties, such as replication and symptom formation in certain differential hosts. Phylogenetic and ecological data indicate that MPVd and certain viroids now affecting crop plants, such as TPMVd, PSTVd, and possibly others, have a common ancestor. We hypothesize that commercial potatoes grown in the United States have become viroid-infected by chance transfer of MPVd or a similar viroid from endemically infected wild solanaceous plants imported from Mexico as germplasm, conceivably from plants known to have been introduced from Mexico to the United States late in the 19th century in efforts to identify genetic resistance to the potato late blight fungus, Phytophthora infestans.

Expression profiling and sequence diversity of novel DREB genes from common bean (Phaseolus vulgaris L.) and their association with drought-related traits

Common bean is a major dietary component in several countries, but its productivity is negatively affected by abiotic stresses. Dissecting candidate genes involved in abiotic stress tolerance is a paramount step toward the improvement of common bean performance under such constraints. Thereby, this thesis presents a systematic analysis of the DEHYDRATION RESPONSIVE ELEMENT-BINDING (DREB) gene subfamily, which encompasses genes that regulate several processes during stress responses, but with limited information for common bean. First, a series of in silico analyses with sequences retrieved from the P. vulgaris genome on Phytozome supported the categorization of 54 putative PvDREB genes distributed within six phylogenetic subgroups (A-1 to A-6), along the 11 chromosomes. Second, we cloned four novel PvDREB genes and determined their inducibility-factors, including the dehydration-, salinity- and cold-inducible genes PvDREB1F and PvDREB5A, and the dehydration- and cold-inducible genes PvDREB2A and PvDREB6B. Afterwards, nucleotide polymorphisms were searched through Sanger sequencing along those genes, revealing a high number of single nucleotide polymorphisms within PvDREB6B by the comparison of Mesoamerican and Andean genotypes. The nomenclature of PvDREB6B is discussed in details. Furthermore, we used the BARCBean6K_3 SNP platform to identify and genotype the closest SNP to each one of the 54 PvDREB genes. We selected PvDREB6B for a broader study encompassing a collection of wild common bean accessions of Mesoamerican origin. The population structure of the wild beans was accessed using sequence polymorphisms of PvDREB6B. The genetic clusters were partially associated with variation in latitude, altitude, precipitation and temperature throughout the areas such beans are distributed. With an emphasis on drought stress, an adapted tube-screening method in greenhouse conditions enabled the phenotyping of several drought-related traits in the wild collection. Interestingly, our data revealed a correlation between root depth, plant height and biomass and the environmental data of the location of the accessions. Correlation was also observed between the population structure determined through PvDREB6B and the environmental data. An association study combining data from the SNP array and DREB polymorphisms enabled the detection of SNP associated with drought-related traits through a compressed mixed linear model (CMLM) analysis. This thesis highlighted important features of DREB genes in common bean, revealing candidates for further strategies aimed at improvement of abiotic stress tolerance, with emphasis on drought tolerance

Oceanic ichthyology : a treatise on the deep-sea and pelagic fishes of the world, based chiefly upon the collections made by the steamers "Blake," "Albatross," and "Fishhawk" in the northwestern Atlantic, with an atlas containing 417 figures / by George Brown Goode and Tarleton H. Bean. Pub. in connection with the National Museum and the Smithsonian institution.

v.22 (1896) text

Oceanic ichthyology : a treatise on the deep-sea and pelagic fishes of the world, based chiefly upon the collections made by the steamers "Blake," "Albatross," and "Fishhawk" in the northwestern Atlantic, with an atlas containing 417 figures / by George Brown Goode and Tarleton H. Bean. Pub. in connection with the National Museum and the Smithsonian institution.

v.22 (1896) atlas

The pragmatics of computer-mediated communication between South African and Mexican drug traffickers

South Africa and Mexico are ripe with drug trafficking. The gangs and syndicates running the drug businesses in these two countries collaborate occasionally. Communication between these international drug business partners takes place on social media. Their main language of communication is English, mixed with some limited use of Spanish and Afrikaans. The key purpose of the interactions between the South African and Mexican parties is the organisation of their business activities. This study aims at examining how the drug traffickers position each other and themselves regarding their common business interest and how their relationship evolves throughout their interactions. Moreover, it is of interest to look at how these people make use of different social media and their affordances. For this a qualitative analysis of the interaction between two drug traffickers (one South African and one Mexican) on Facebook, Threema and PlayStation 4 was performed. Computer-mediated communication between these two main informants was studied at various stages of their relationship. Results show that at first the interaction between the South African and Mexican drug traffickers consists of interpersonal negotiations of power. The high risk of the drug business and gang/syndicate membership paired with intercultural frictions causes the two interlocutors to be extremely cautious and at the same time to mark their position. As their relationship develops and they gain trust in each other a shift to interpersonal negotiations of solidarity takes place. In these discursive practices diverse linguistic strategies are employed for creating relational effects and for positioning the other and the self. The discursive activities of the interactants are also identity practices. Thus, the two drug traffickers construct identities through these social practices, positioning and their interpersonal relationship.

Viva la Raza : Mexican American education, a search for identity.

"Reprints from American Education."