Proposal of Xanthomonas translucens pv. pistaciae pv. nov., pathogenic to pistachio (Pistacia vera)

Strains of Xanthomonas translucens have caused dieback in the Australian pistachio industry for the last 15 years. Such pathogenicity to a dicotyledonous woody host contrasts with that of other pathovars of X. translucens, which are characterized by their pathogenicity to monocotyledonous plant families. Further investigations, using DNA-DNA hybridization, gyrB gene sequencing and integron screening, were conducted to confirm the taxonomic status of the X. translucens pathogenic to pistachio. DNA-DNA hybridization provided a clear classification, at the species level, of the pistachio pathogen as a X. translucens. In the gyrB-based phylogeny, strains of the pistachio pathogen clustered among the X. translucens pathovars as two distinct lineages. Integron screening revealed that the cassette arrays of strains of the pistachio pathogen were different from those of other Xanthomonas species, and again distinguished two groups. Together with previously reported pathogenicity data, these results confirm that the pistachio pathogen is a new pathovar of X. translucens and allow hypotheses about its origin. The proposed name is Xanthomonas translucens pv. pistaciae pv. nov.     

α-Synuclein and Its A30P Mutant Affect Actin Cytoskeletal Structure and Dynamics

The function of α-synuclein, a soluble protein abundant in the brain and concentrated at presynaptic terminals, is still undefined. Yet, α-synuclein overexpression and the expression of its A30P mutant are associated with familial Parkinson''s disease. Working in cell-free conditions, in two cell lines as well as in primary neurons we demonstrate that α-synuclein and its A30P mutant have different effects on actin polymerization. Wild-type α-synuclein binds actin, slows down its polymerization and accelerates its depolymerization, probably by monomer sequestration; A30P mutant α-synuclein increases the rate of actin polymerization and disrupts the cytoskeleton during reassembly of actin filaments. Consequently, in cells expressing mutant α-synuclein, cytoskeleton-dependent processes, such as cell migration, are inhibited, while exo- and endocytic traffic is altered. In hippocampal neurons from mice carrying a deletion of the α-synuclein gene, electroporation of wild-type α-synuclein increases actin instability during remodeling, with growth of lamellipodia-like structures and apparent cell enlargement, whereas A30P α-synuclein induces discrete actin-rich foci during cytoskeleton reassembly. In conclusion, α-synuclein appears to play a major role in actin cytoskeletal dynamics and various aspects of microfilament function. Actin cytoskeletal disruption induced by the A30P mutant might alter various cellular processes and thereby play a role in the pathogenesis of neurodegeneration.     

Structure of the O-polysaccharide of Pragia fontium 27480 containing 2,3-diacetamido-2,3-dideoxy-d-mannuronic acid

The following structure of the O-polysaccharide of Pragia fontium 27480 was elucidated by sugar analysis, including determination of the absolute configurations of the monosaccharides, and Smith degradation along with 1D and 2D ¹H and ¹³C NMR spectroscopy:→4)-β-d-ManpNAc3NAcA-(1→2)-α-l-Rhap-(1→3)-β-l-Rhap-(1→4)-α-d-GlcpNAc-(1→where ManNAc3NAcA stands for 2,3-diacetamido-2,3-dideoxymannuronic acid.     

Influence of extremely low-frequency electric fields on the growth of Vigna radiata seedlings

The biological effects of extremely low-frequency electric fields (ELF) on living organisms have been explored in many studies, but the results are controversial and only a few studies investigated the influence of the intensity of the applied field on seedling growth. Here we assess the effects of a 50 Hz sinusoidal electric field on the early growth of Vigna radiata seedlings while varying the field intensity. Experiments performed in a dark, constant-climate chamber on several thousands of seedlings show that the field produces an inhibitory effect at a low field intensity and an enhancing one at a higher intensity. The maximum negative effect occurs at about 450 V/m, which is an intensity much lower than the exposure limits currently in force in the safety regulations.     

Mycorrhizal responses in wheat: shading decreases growth but does not lower the contribution of the fungal phosphate uptake pathway

Effects have been investigated of reduced C supply (induced by shade) on arbuscular mycorrhizal (AM) colonisation, mycorrhizal growth responses (MGRs) and on AM-mediated and direct uptake of phosphate (Pi) (using ³²P) in wheat, a plant that does not usually respond positively to AM colonisation. Shading markedly reduced growth and shoot/root dry weight ratios of both AM and non-mycorrhizal wheat, indicating decreased photosynthetic C supply. However, shading had very little effect on percent root length colonised by Rhizophagus irregularis or Gigaspora margarita or on MGRs, which remained slightly positive or zero, regardless of shade; there were no growth depressions under shade. By 6 weeks, when the contributions of the AM pathway were measured with ³²P supplied in small hyphal compartments, R. irregularis had supplied 23 to 28 % of shoot P with no significant effect of shading. Data show that reduced C availability did not reduce the contribution of the AM pathway to plant P, so the fungi were not acting physiologically as parasites. These results support our previous hypothesis that lack of positive MGR is not necessarily the outcome of excessive C use by the fungi or failure to deliver P via the AM pathway.     

The spleen and skin wound healing in Xenopus adults

In most vertebrates, the regenerative capacity to restore lost/damage tissues to original structure and functionality decreases at some time during ontogenesis. To evaluate the role of the acquired immunity in the decline of regenerative potential, we examined the cellular responses elicited in the spleen during skin repair in Xenopus adults. Modifications in the architecture were found to be induced and were remarkable 14 days postinjury when the spleen increased significantly in size. In white pulp, the periarteriolar lymphoid sheaths were associated with follicles having central light zones, morphologically similar to germinal centers. With the progress of healing, pigment‐containing cells were seen to accumulate in both white and red pulp regions. Moreover, compared to controls, the cells immunoreactive to anti‐cytokines (TNF‐α, TGF‐β1) and ‐iNOS increased from the first days after wounding. The 14th day, the positive cells formed a dense network of reticular cells in central regions of lymphoid follicles and more frequent reactive leukocytes were detected within the red pulp. A higher number of lymphoid cells immunostained with anti‐CD3ε were also observed in the perifollicular zone. The results suggest that the spleen of adult frogs is involved in skin wound healing with the expansion of lymphoid compartments. J. Morphol. 277:888–895, 2016. © 2016 Wiley Periodicals, Inc.     

Effect of the three-dimensional organization of liver cells on the biogenesis of the γ-glutamyltransferase fraction pattern

Context Four gamma-glutamyltransferase (GGT) fractions with different molecular weights (big-, medium-, small- and free-GGT) are detectable in human plasma. Objective Verify if liver cells can release all four GGT fractions and if the spatial cell organization influences their release. Methods Hepatoma (HepG2) and melanoma (Me665/2/60) cells were cultured as monolayers or spheroids. GGT released in culture media was analysed by gel-filtration chromatography. Results HepG2 and Me665/2/60 monolayers released the b-GGT fraction, while significative levels of s-GGT and f-GGT were detectable only in media of HepG2-spheroids. Bile acids alone or in combination with papain promoted the conversion of b-GGT in s-GGT or f-GGT, respectively. Conclusions GGT is usually released as b-GGT, while s-GGT and f-GGT are likely to be produced in the liver extracellular environment by the combined action of bile acids and proteases.     

The LSH/DDM1 Homolog MUS-30 Is Required for Genome Stability,but Not for DNA Methylation in Neurospora crassa

LSH/DDM1 enzymes are required for DNA methylation in higher eukaryotes and have poorly defined roles in genome maintenance in yeast, plants, and animals. The filamentous fungus Neurospora crassa is a tractable system that encodes a single LSH/DDM1 homolog (NCU06306). We report that the Neurospora LSH/DDM1 enzyme is encoded by mutagen sensitive-30 (mus-30), a locus identified in a genetic screen over 25 years ago. We show that MUS-30-deficient cells have normal DNA methylation, but are hypersensitive to DNA damaging agents. MUS-30 is a nuclear protein, consistent with its predicted role as a chromatin remodeling enzyme, and levels of MUS-30 are increased following DNA damage. MUS-30 co-purifies with Neurospora WDR76, a homolog of yeast Changed Mutation Rate-1 and mammalian WD40 repeat domain 76. Deletion of wdr76 rescued DNA damage-hypersensitivity of Δmus-30 strains, demonstrating that the MUS-30-WDR76 interaction is functionally important. DNA damage-sensitivity of Δmus-30 is partially suppressed by deletion of methyl adenine glycosylase-1, a component of the base excision repair machinery (BER); however, the rate of BER is not affected in Δmus-30 strains. We found that MUS-30-deficient cells are not defective for DSB repair, and we observed a negative genetic interaction between Δmus-30 and Δmei-3, the Neurospora RAD51 homolog required for homologous recombination. Together, our findings suggest that MUS-30, an LSH/DDM1 homolog, is required to prevent DNA damage arising from toxic base excision repair intermediates. Overall, our study provides important new information about the functions of the LSH/DDM1 family of enzymes.     

Time‐resolved spectral measurements of delayed luminescence from a single soybean seed: effects of thermal damage and correlation with germination performance

Delayed luminescence from a single dry soybean seed was investigated in both spectral and time domains, under different excitation wavelengths. Emission spectra were collected, under 337 nm laser excitation, from native and artificially deteriorated seeds and the time‐dependence of different spectral components was analyzed in detail. The single seed viability was evaluated through observation of germination properties after imbibition and compared with different parameters related to the luminescence kinetics. The significant correlation found between single seed delayed luminescence parameters and germination capability strongly validates the connection of this phenomenon with the functional state of the system and suggests the development of a non‐invasive technique for seed quality determination. Copyright © 2009 John Wiley & Sons, Ltd.