Abscisic acid, gibberellin and cell viability in cereal aleurone

The aleurone layer of cereals is a secretory tissue whose activity is regulated by abscisic acid (ABA) and gibberellins (GAs). Whereas GA triggers enzyme synthesis and secretion and initiates a program that culminates in cell death, ABA prevents enzyme production and cell death. Reactive oxygen species (ROS) are key players in regulating cell viability and GA sensitizes the aleurone cell to ROS. Sensitivity of GA-treated cells results in part from a reduction in steady-state amounts of mRNAs encoding enzymes that scavenge ROS. mRNAs encoding catalase, superoxide dismutase and ascorbate peroxidase are almost undetectable in aleurone layers 24 h after incubation in GA. For layers incubated in ABA, however, the amounts of these mRNAs increase. Western blotting and enzyme activity assays confirm that GA but not ABA reduced the amount and activity of ROS scavenging enzymes (Fath et al., 2001b). Substantial amounts of ROS are produced by enzymes engaged in lipid metabolism, and by the electron transport chain in the mitochondria. Aleurone layers contain abundant stores of triglycerides and ROS are produced as these lipids are rapidly converted to sugars. We hypothesize that the ROS produced in GA-treated aleurone cells bring about cell death by disrupting the plasma membrane. Aleurone cells incubated in ABA, on the other hand, are better able to maintain redox balance. ABA does not initiate rapid triglyceride metabolism, and the activities of ROS-scavenging enzymes remain high in ABA-treated cells. We conclude that GA initiates a metabolic cascade in aleurone cells that results in death from ROS. ABA maintains viability by keeping ROS under control. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enzymatic solubilization of arabinoxylans from native, extruded, and high-shear-treated rye bran by different endo-xylanases and other hydrolyzing enzymes

The overall objective of this research was to find a new way to valorize rye bran, by producing a gellifier from the enzymatic solubilization of arabinoxylans (AX). The effects of three pure endo-xylanases from Aspergillus niger (Xyl-1), Talaromyces emersonii (Xyl-2), and Bacillus subtilis (Xyl-3) and of Grindamyl S100 (GS100), a commercial enzyme preparation containing a Xyl-1 type endo-xylanase, were tested on rye bran to study the solubilization of water-unextractable arabinoxylans (WUAX). Eight different extrusion-treated rye brans were also used as substrates to find the best physical treatment to facilitate enzymatic arabinoxylan (AX) solubilization. Arabinoxylans were better solubilized from the bran extruded at high temperature using Xyl-3. This enzyme was then tested in combination with pure (1,4)-beta-d-arabinoxylan arabinofuranohydrolase (AXH) and endo-beta-d-glucanase or ferulic acid esterase (FAE), from A. niger. Only beta-glucanase in combination with Xyl-3 improved the AX extraction, but it did not have a marked effect on the viscosity of the extracts. Xyl-3 was then tested on a high-shear-treated rye bran, and results were compared to those obtained with the high-temperature-extruded rye bran. The high-shear treatment did not improve the bran AX enzymatic solubilization. The combination of FAE with Xyl-1 or Xyl-3 did not improve the AX extraction from untreated and high-shear-treated rye bran. Finally, to study the gelation capacity of the enzymatically solubilized AX, the effect of the hydrogen peroxide/horseradish peroxidase (H(2)O(2)/POD) was tested on the Xyl-3 high-temperature-extruded bran extracts. Solubilized AX did not gel in the presence of the oxidizing system.     

Acrylamide in Processed Potato Products

Trace amounts of acrylamide are present in many foods cooked at high temperatures. Acrylamide in processed potato products is formed from reducing sugars and asparagine and is a product of the Maillard reaction; this reaction typically occurs during frying and baking of food products. Processed potato products, including fries and chips, are relatively high in acrylamide compared with other foods and contribute substantially to dietary acrylamide. Acrylamide content in potato products is strongly affected by processing conditions, potato variety, field management, environmental conditions during tuber growth, and tuber storage conditions. Numerous approaches have been described that could potentially reduce the acrylamide content of potato products, but many influence finished product sensory attributes and may be difficult to implement. Health concerns related to acrylamide in food center on its role as a potential carcinogen. Research using feeding studies with rodent models and epidemiological studies with humans are ongoing and are likely to provide future guidance for acceptable amounts of acrylamide in food.     

Mapping of QTLs controlling epicotyl length in adzuki bean (Vigna angularis)

Epicotyl length (ECL) of adzuki bean (Vigna angularis) affects the efficiency of mechanized weeding and harvest. The present study investigated the genetic factors controlling ECL. An F₂ population derived from a cross between the breeding line ‘Tokei1121’ (T1121, long epicotyls) and the cultivar ‘Erimo167’ (common epicotyls) was phenotyped for ECL and genotyped using simple sequence repeats (SSRs) and single-nucleotide polymorphism (SNP) markers. A molecular linkage map was generated and fifty-two segregating markers, including 27 SSRs and 25 SNPs, were located on seven linkage groups (LGs) at a LOD threshold value of 3.0. Four quantitative trait loci (QTLs) for ECL, with LOD scores of 4.0, 3.4, 4.8 and 6.4, were identified on LGs 2, 4, 7 and 10, respectively; together, these four QTLs accounted for 49.3% of the phenotypic variance. The segregation patterns observed in F₅ residual heterozygous lines at qECL10 revealed that a single recessive gene derived from T1121 contributed to the longer ECL phenotype. Using five insertion and deletion markers, this gene was fine mapped to a ~255 kb region near the end of LG10. These findings will facilitate marker-assisted selection for breeding in the adzuki bean and contribute to an understanding of the mechanisms associated with epicotyl elongation.     

Phenotypical parameters as a tool to evaluate the immunostimulatory effects of laminarin in Oncorhynchus mykiss

Laminarin is a β‐glucan from the brown algae Laminaria digitata (J.V. Lamour), which can activate innate immune responses. With the aim of developing a strategy to evaluate specific phenotypical parameters of the effects of laminarin in trout innate immunity, we (i) fed fish with laminarin‐supplemented diet (0.2 g kg^?1 day^?1) for 21 days and (ii) treated fish with a single dose of intraperitoneal injected laminarin (0.08 g kg^?1 fish). The evaluation of cellular and humoral immune parameters was established at phenotypic level by the phagocytic activity of headkidney macrophages and detection of inflammatory cytokines in head kidney and gill tissue by indirect ELISA. Results showed that both delivery methods of laminarin produce an increase in the phagocytic activity in head kidney macrophages and a significant increase in the production of TNFα and IL‐8 in gill tissue at day 21. Additionally, some of these parameters were significantly correlated (P < 0.025), which places them as new potential combined markers to detect activation of trout defense mechanisms by laminarin. These results highlight the importance of developing new protocols to quantitate immune parameters, in order to evaluate immunostimulants in fish farming.     

Iron acquisition and siderophore production in the fish pathogen Renibacterium salmoninarum

Renibacterium salmoninarum is the causative agent of bacterial kidney disease, which significantly affects salmonid farming worldwide. Despite this impact, there is scarce data on its iron uptake ability, a factor of pathogenesis. This study investigated the iron acquisition mechanisms of R. salmoninarum and its capacity to uptake iron from different sources. Thirty‐two Chilean isolates and the DSM20767^T type strain grew in the presence of 2,2′‐Dipyridyl at varying concentrations (250–330 μm ), and all isolates positively reacted on chrome azurol S agar. Subsequently, inocula of four Chilean isolates and the type strain were prepared with or without 200 μm of 2,2′‐Dipyridyl for uptake assays. Assay results revealed differences between the isolates in terms of iron acquisition. While a prior iron‐limited environment was, for most isolates, not required to activate the uptake of iron (II) sulphate, ammonium iron (III) citrate or iron (III) chloride at higher concentrations (100 μm ), it did facilitate growth at lower iron concentrations (10 μm and 1 μm ). An exception was the H‐2 isolate, which only grew with 100 μm of iron sulphide. In turn, 100 μm of haemin was toxic when isolates were grown in normal KDM‐2. In silico R. salmoninarumATCC 33209^T genome analysis detected various genes coding iron uptake‐related proteins. This is the first study indicating two iron acquisition systems in R. salmoninarum: one involving siderophores and another involving haem group utilization. These data represent a first step towards fully elucidating this virulence factor in the pathogenic R. salmoninarum.     

Plant‐based fertilizers for organic vegetable production

To ensure high yield and quality in organic vegetable production, crops often require additional fertilizer applied during the season. Due to the risk of contamination of edible plant products from slurry, plant‐based fertilizers may be used as an alternative. The purpose of our work was to develop mobile green manures with specific high nutrient concentrations (e.g., nitrogen [N], sulfur [S], and phosphorus [P]) that are released quickly after soil incorporation and that are easy to handle during storage and application. To distinguish from traditional green manures that are grown to improve soil fertility, the term “mobile green manures” is used for green‐manure crops that are harvested in one field and then moved as a whole and used as fertilizer in other fields. To further investigate mobile‐green‐manure crops for use as efficient fertilizers, pot and field experiments were conducted with cauliflower (Brassica oleracea botrytis) and kale (Brassica oleracea sabellica) supplied with organic matter consisting of a wide range of plant species with varying nutrient concentrations. Further, field experiments were conducted with leek (Allium porrum) and celery (Apium graveolens dulce) supplied with increasing amounts of organic matter consisting of fresh, ensiled, or dried green manures. Results show that garden sorrel (Rumex acetosa), dyer's woad (Isatis tinctoria), and fodder radish (Raphanus sativus) harvested with a high leaf‐to‐stem ratio resulted in high P concentration, and cruciferous crops in high S concentration. Dyer's woad, salad burnet (Sanguisorba minor), and stinging nettle (Urtica dioica) showed high boron (B) concentration, whereas species such as dandelion (Taraxacum officinale), chicory (Cichorium intybus), and garden sorrel showed high potassium (K) concentration. Green manures with high P and S concentrations increased the nutrient uptake and yield of pot‐grown cauliflower and kale. Field experiments showed that the production of cauliflower and kale decreased when the carbon‐to‐nitrogen (C : N) ratio of applied green manure increased. In kale, for example, application of 160 kg N ha^–1 in early harvested lucerne (Medicago sativa) with a C : N ratio of 10 resulted in the highest kale production whereas application of an equal amount of N in late harvested lucerne with a C : N ratio of 20 produced 34% less. Differences in vegetable production were not due to the amount of N applied, but to the N availability. Field experiments with fresh, ensiled, or dry green manure applied to leek and celery showed that the C : N ratio has to be low to get a fast response. Further, these field experiments demonstrate the importance of green manures, which can be stored and are easy to handle during transport, crop application, and soil incorporation. It is concluded that it is possible to produce green manures with high concentrations of S, P, K, and B, and low C : N ratios and that these properties have a great impact on the value of the green manure for vegetable production.     

Development of a new antibody for detecting natural killer enhancing factor (NKEF)-like protein in infected salmonids

The main cellular responses of innate immunity are phagocytic activity and the respiratory burst, which produces a high amount of reactive oxygen species. Natural killer enhancing factor (NKEF) belongs to the peroxiredoxin family that has an antioxidant function and enhances cytotoxic cell activity. This molecule may play a key role in macrophage and cytotoxic cell communication during the innate immune response of fish against pathogens. In fish, the NKEF gene has been characterized in some species as showing an up-regulation in infected fish, suggesting a trigger effect upon NK-like cells. To detect and localize this molecule in salmonids at protein level, a monospecific polyclonal antibody was generated. A probable NKEF-like protein epitope region was identified and characterized using bioinformatic tools, and the sequence was chemically synthesized using Fmoc strategy, analysed by RP-HPLC and its molecular weight confirmed by mass spectrometry. The synthetic peptide was immunized and antibodies from ascitic fluid were obtained. The resulting antibody is a versatile tool for detecting NKEF by different immune techniques such as ELISA, Western blotting and immunohistochemistry. Analysis of NKEF-like protein is a useful method for characterizing immune properties of this molecule in fish during response to pathogens.     

A clathrate reservoir hypothesis for Enceladus' south polar plume

We hypothesize that active tectonic processes in the south polar terrain of Enceladus, the 500-kilometer-diameter moon of Saturn, are creating fractures that cause degassing of a clathrate reservoir to produce the plume documented by the instruments on the Cassini spacecraft. Advection of gas and ice transports energy, supplied at depth as latent heat of clathrate decomposition, to shallower levels, where it reappears as latent heat of condensation of ice. The plume itself, which has a discharge rate comparable to Old Faithful Geyser in Yellowstone National Park, probably represents small leaks from this massive advective system.     

Understanding the dynamics of neonicotinoid activity in the management of Bemisia tabaci whiteflies on poinsettias

The relative efficacies of registered label rates for foliar and soil drench treatments of imidacloprid and dinotefuran at preventing the establishment of Bemisia tabaci B biotype whitefly populations on newly infested poinsettia plants were evaluated. Pesticide levels within and on plant leaves were monitored for 10 weeks by ELISA and LC/MS in an effort to better understand the dynamics of neonicotinoid activity against this insect and to estimate insecticide concentrations needed to kill the nymphal and adult stages. While all treatments proved equally effective as a remedial measure for the control of the resident adult populations, thereby accomplishing the objective of foliar contact treatments, the dinotefuran soil drench application was the only treatment that provided multi-generational control of Bemisia populations.