Symptoms induced by transgenic expression of p23 from Citrus tristeza virus in phloem‐associated cells of Mexican lime mimic virus infection without the aberrations accompanying constitutive expression

Citrus tristeza virus (CTV) is phloem restricted in natural citrus hosts. The 23‐kDa protein (p23) encoded by the virus is an RNA silencing suppressor and a pathogenicity determinant. The expression of p23, or its N‐terminal 157‐amino‐acid fragment comprising the zinc finger and flanking basic motifs, driven by the constitutive 35S promoter of cauliflower mosaic virus, induces CTV‐like symptoms and other aberrations in transgenic citrus. To better define the role of p23 in CTV pathogenesis, we compared the phenotypes of Mexican lime transformed with p23‐derived transgenes from the severe T36 and mild T317 CTV isolates under the control of the phloem‐specific promoter from Commelina yellow mottle virus (CoYMV) or the 35S promoter. Expression of the constructs restricted to the phloem induced a phenotype resembling CTV‐specific symptoms (vein clearing and necrosis, and stem pitting), but not the non‐specific aberrations (such as mature leaf epinasty and yellow pinpoints, growth cessation and apical necrosis) observed when p23 was ectopically expressed. Furthermore, vein necrosis and stem pitting in Mexican lime appeared to be specifically associated with p23 from T36. Phloem‐specific accumulation of the p23Δ158–209(T36) fragment was sufficient to induce the same anomalies, indicating that the region comprising the N‐terminal 157 amino acids of p23 is responsible (at least in part) for the vein clearing, stem pitting and, possibly, vein corking in this host.     

Acidithiobacillus ferrianus sp. nov.: an ancestral extremely acidophilic and facultatively anaerobic chemolithoautotroph

Strain MG, isolated from an acidic pond sediment on the island of Milos (Greece), is proposed as a novel species of ferrous iron- and sulfur-oxidizing Acidithiobacillus. Currently, four of the eight validated species of this genus oxidize ferrous iron, and strain MG shares many key characteristics with these four, including the capacities for catalyzing the oxidative dissolution of pyrite and for anaerobic growth via ferric iron respiration. Strain MG also grows aerobically on hydrogen and anaerobically on hydrogen coupled to ferric iron reduction. While the 16S rRNA genes of the iron-oxidizing Acidi-thiobacillus species (and strain MG) are located in a distinct phylogenetic clade and are closely related (98–99% 16S rRNA gene identity), genomic relatedness indexes (ANI/dDDH) revealed strong genomic divergence between strain MG and all sequenced type strains of the taxon, and placed MG as the first cultured representative of an ancestral phylotype of iron oxidizing acidithiobacilli. Strain MG is proposed as a novel species, Acidithiobacillus ferrianus sp. nov. The type strain is MG^T (= DSM 107098^T = JCM 33084^T). Similar strains have been found as isolates or indicated by cloned 16S rRNA genes from several mineral sulfide mine sites.

     

Dark microbial CO2 fixation in temperate forest soils increases with CO2 concentration

Dark, that is, nonphototrophic, microbial CO₂ fixation occurs in a large range of soils. However, it is still not known whether dark microbial CO₂ fixation substantially contributes to the C balance of soils and what factors control this process. Therefore, the objective of this study was to quantitate dark microbial CO₂ fixation in temperate forest soils, to determine the relationship between the soil CO₂ concentration and dark microbial CO₂ fixation, and to estimate the relative contribution of different microbial groups to dark CO₂ fixation. For this purpose, we conducted a ¹³C‐CO₂ labeling experiment. We found that the rates of dark microbial CO₂ fixation were positively correlated with the CO₂ concentration in all soils. Dark microbial CO₂ fixation amounted to up to 320 µg C kg^?1 soil day^?1 in the Ah horizon. The fixation rates were 2.8–8.9 times higher in the Ah horizon than in the Bw1 horizon. Although the rates of dark microbial fixation were small compared to the respiration rate (1.2%–3.9% of the respiration rate), our findings suggest that organic matter formed by microorganisms from CO₂ contributes to the soil organic matter pool, especially given that microbial detritus is more stable in soil than plant detritus. Phospholipid fatty acid analyses indicated that CO₂ was mostly fixed by gram‐positive bacteria, and not by fungi. In conclusion, our study shows that the dark microbial CO₂ fixation rate in temperate forest soils increases in periods of high CO₂ concentrations, that dark microbial CO₂ fixation is mostly accomplished by gram‐positive bacteria, and that dark microbial CO₂ fixation contributes to the formation of soil organic matter.     

Prevalence of airborne fungal spores in two potato warehouses with different storage conditions

Aerobiologia - Potatoes production is the main source of income in A Limia (Northwest Spain). Most of the potatoes harvest is stored in piles in farmer´s warehouses without systems to control...     

Reduction and cyclization in biotransformation of carbonyl compounds by cultured cells of Taxus species

Cultured plant cells from Taxus brevifolia Nutt and Taxus globosa Schltdl were investigated as biocatalysts using exogenous substrates. Production of highly specific metabolites by these species prompted us to analyse their synthetic potential. Whole cells suspensions have the capacity to chemoselectively reduce ethyl acetoacetate to ethyl 3-hydroxybutyrate chemo- and stereoselectively reduce rac-2-benzoylcyclohexanone to (1R, 2S)- and (1S, 2S)-2-hydroxycyclohexylphenylmethanones, and to cyclize N-phthaloyl-L-glutamine to thalidomide.     

Placental tissue metabolome analysis by GC-MS: Oven-drying is a viable sample preparation method

Abstract

Analysis of the human placenta metabolome has great potential to advance the understanding of complicated pregnancies and deleterious fetal outcomes in remote populations, but samples preparation can present unique challenges. Herein, we introduce oven-drying as a simple and widely available method of sample preparation that will facilitate investigations of the placental metabolome from remote and under-studied populations. Placentae from complicated and uncomplicated pregnancies were prepared in three ways (oven-dried at 60?°C, fresh, lyophilized) for metabolome analysis via gas chromatography-mass spectrometry (GC-MS). Multiple computer models (e.g. PLS-DA, ANN) were employed to classify and determine if there was a difference in placentae metabolome and a group of metabolites with high variable importance in projection scores across the three preparations and by complicated vs. control groups. The analyses used herein were shown to be thorough and sensitive. Indeed, significant differences were detected in metabolomes of complicated vs. uncomplicated pregnancies; however, there were no statistical differences in the metabolome of placentae prepared by oven-drying vs. lyophilization vs. fresh placentae. Oven-drying is a viable sample preparation method for placentae intended for use in metabolite analysis via GC-MS. These results open many possibilities for researching metabolome patterns associated with fetal outcomes in remote and resource-poor communities worldwide.     

Inhibition of Acid Phosphatase Isoforms Purified from Mature Soybean (Glyczne MAX) Seeds

The four soybean seed acid phosphatase isoforms AP1, AP2, AP3A and AP3B were competitively inhibited by phosphate, vanadate, fluoride and molybdate, using p-nitrophenylphos-phate as substrate. The four isoforms were not significantly affected by compounds that can interact with SH residues or by pyridoxal phosphate. These results indicated that cysteine and lysine residues are not present in the active site of the four soybean seed acid phosphatase isoforms. The inhibition constant values for phosphate, vanadate, fluoride and molybdate at pH 5.0 were respectively: API (250, 12.8, 1.7, 0.05 μM), AP2 (800,10, 500, 0.025 μM), AP3A (250, 24.2,250, 0.032 μM), AP3B (2400, 36.9,750, 0.05 μM).