56 research outputs found

    Barley Ror1 encodes a class XI myosin required for mlo-based broad-spectrum resistance to the fungal powdery mildew pathogen

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    Loss-of-function alleles of plant MLO genes confer broad-spectrum resistance to powdery mildews in many eudicot and monocot species. Although barley (Hordeum vulgare) mlo mutants have been used in agriculture for more than 40 years, understanding of the molecular principles underlying this type of disease resistance remains fragmentary. Forward genetic screens in barley have revealed mutations in two Required for mlo resistance (Ror) genes that partially impair immunity conferred by mlo mutants. While Ror2 encodes a soluble N-ethylmaleimide-sensitive factor-attached protein receptor (SNARE), the identity of Ror1, located at the pericentromeric region of barley chromosome 1H, remained elusive. We report the identification of Ror1 based on combined barley genomic sequence information and transcriptomic data from ror1 mutant plants. Ror1 encodes the barley class XI myosin Myo11A (HORVU.MOREX.r3.1HG0046420). Single amino acid substitutions of this myosin, deduced from non-functional ror1 mutant alleles, map to the nucleotide-binding region and the interface between the relay-helix and the converter domain of the motor protein. Ror1 myosin accumulates transiently in the course of powdery mildew infection. Functional fluorophore-labeled Ror1 variants associate with mobile intracellular compartments that partially colocalize with peroxisomes. Single-cell expression of the Ror1 tail region causes a dominant-negative effect that phenocopies ror1 loss-of-function mutants. We define a myosin motor for the establishment of mlo-mediated resistance, suggesting that motor protein-driven intracellular transport processes are critical for extracellular immunity, possibly through the targeted transfer of antifungal and/or cell wall cargoes to pathogen contact sites

    Phylogenetic Distribution of Intron Positions in Alpha-Amylase Genes of Bilateria Suggests Numerous Gains and Losses

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    Most eukaryotes have at least some genes interrupted by introns. While it is well accepted that introns were already present at moderate density in the last eukaryote common ancestor, the conspicuous diversity of intron density among genomes suggests a complex evolutionary history, with marked differences between phyla. The question of the rates of intron gains and loss in the course of evolution and factors influencing them remains controversial. We have investigated a single gene family, alpha-amylase, in 55 species covering a variety of animal phyla. Comparison of intron positions across phyla suggests a complex history, with a likely ancestral intronless gene undergoing frequent intron loss and gain, leading to extant intron/exon structures that are highly variable, even among species from the same phylum. Because introns are known to play no regulatory role in this gene and there is no alternative splicing, the structural differences may be interpreted more easily: intron positions, sizes, losses or gains may be more likely related to factors linked to splicing mechanisms and requirements, and to recognition of introns and exons, or to more extrinsic factors, such as life cycle and population size. We have shown that intron losses outnumbered gains in recent periods, but that “resets” of intron positions occurred at the origin of several phyla, including vertebrates. Rates of gain and loss appear to be positively correlated. No phase preference was found. We also found evidence for parallel gains and for intron sliding. Presence of introns at given positions was correlated to a strong protosplice consensus sequence AG/G, which was much weaker in the absence of intron. In contrast, recent intron insertions were not associated with a specific sequence. In animal Amy genes, population size and generation time seem to have played only minor roles in shaping gene structures

    Phylogenomics of the Reproductive Parasite Wolbachia pipientis wMel: A Streamlined Genome Overrun by Mobile Genetic Elements

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    The complete sequence of the 1,267,782 bp genome of Wolbachia pipientis wMel, an obligate intracellular bacteria of Drosophila melanogaster, has been determined. Wolbachia, which are found in a variety of invertebrate species, are of great interest due to their diverse interactions with different hosts, which range from many forms of reproductive parasitism to mutualistic symbioses. Analysis of the wMel genome, in particular phylogenomic comparisons with other intracellular bacteria, has revealed many insights into the biology and evolution of wMel and Wolbachia in general. For example, the wMel genome is unique among sequenced obligate intracellular species in both being highly streamlined and containing very high levels of repetitive DNA and mobile DNA elements. This observation, coupled with multiple evolutionary reconstructions, suggests that natural selection is somewhat inefficient in wMel, most likely owing to the occurrence of repeated population bottlenecks. Genome analysis predicts many metabolic differences with the closely related Rickettsia species, including the presence of intact glycolysis and purine synthesis, which may compensate for an inability to obtain ATP directly from its host, as Rickettsia can. Other discoveries include the apparent inability of wMel to synthesize lipopolysaccharide and the presence of the most genes encoding proteins with ankyrin repeat domains of any prokaryotic genome yet sequenced. Despite the ability of wMel to infect the germline of its host, we find no evidence for either recent lateral gene transfer between wMel and D. melanogaster or older transfers between Wolbachia and any host. Evolutionary analysis further supports the hypothesis that mitochondria share a common ancestor with the α-Proteobacteria, but shows little support for the grouping of mitochondria with species in the order Rickettsiales. With the availability of the complete genomes of both species and excellent genetic tools for the host, the wMel–D. melanogaster symbiosis is now an ideal system for studying the biology and evolution of Wolbachia infections

    Effects of L-Carnitine supplement on plasma coagulation and anticoagulation factors in hemodialysis patients

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    Background: Hypercoagulability is an important risk factor for thrombosis and its complications in hemodialysis patients. This study was designed to investigate the effects of l-carnitine supplement on plasma coagulation and anticoagulation factors in hemodialysis patients. Methods: Thirty-six hemodialysis patients were randomly assigned to either a carnitine or a placebo group. Patients in the carnitine group received 1000 mgday oral l-carnitine for 12 weeks, whereas patients in the placebo group received a corresponding placebo. At baseline and the end of week 12, 5 mL blood was collected after a 12- to 14-hour fast and plasma fibrinogen concentration, activity of plasma protein C, coagulation factors V, VII, IX, and serum concentrations of tissue plasminogen activator (tPA), plasminogen activator inhibitor type-1 (PAI-1), free carnitine, and C-reactive protein (CRP) were measured. Results: In the carnitine group, mean serum free carnitine concentration increased significantly to 150 of baseline (p < 0.001), whereas plasma fibrinogen and serum CRP had 98 mg/dL (p < 0.01) and 41 (p < 0.01) significant decreases, respectively, at the end of week 12 compared with baseline. The reductions were significant compared with the placebo group (p < 0.05). No significant differences were observed between the two groups with regard to mean changes of the activity of plasma protein C, coagulation factors V, VII, IX, and serum PAI-1 to tPA ratio. Conclusion: l-Carnitine supplement reduces serum CRP, a marker of systemic inflammation, and plasma fibrinogen, an inflammation-related coagulation factor, in hemodialysis patients. Therefore, l-carnitine may play an effective role in preventing cardiovascular diseases in these patients. © 2010 Informa UK Ltd

    The caspase-3 inhibitor (peptide Z-DEVD-FMK) affects the survival and function of platelets in platelet concentrate during storage

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    Background: Although apoptosis occurs in nucleated cells, studies show that this event also occurs in some anucleated cells such as platelets. During storage of platelets, the viability of platelets decreased, storage lesions were observed, and cells underwent apoptosis. We investigated the effects of caspase-3 inhibitor on the survival and function of platelets after different periods of storage. Methods: Platelet concentrates were obtained from the Iranian Blood Transfusion Organization in plastic blood bags. Caspase-3 inhibitor (Z-DEVD-FMK) was added to the bags. These bags along with control bags to which no inhibitor was added were stored in a shaking incubator at 22oC for 7 days. The effects of Z-DEVD-FMK on the functionality of platelets were analyzed by assessing their ability to bind to von Willebrand factor (vWF) and to aggregate in the presence of arachidonic acid and ristocetin. Cell survival was surveyed by MTT assay. Results: At day 4 of storage, ristocetin-induced platelet aggregation was significantly higher in the inhibitor-treated (test) than in control samples; the difference was not significant at day 7. There was no significant difference in arachidonic acid-induced platelet aggregation between test and control samples. However, at day 7 of storage, the binding of platelets to vWF was significantly higher in test than in control samples. The MTT assay revealed significantly higher viability in test than in control samples at both days of study. Conclusion: Treatment of platelets with caspase-3 inhibitor could increase their functionality and survival. © 2014 Korean Society of Hematology

    Do neural networks for segmentation understand insideness?

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    The insideness problem is an aspect of image segmentation that consists of determining which pixels are inside and outside a region. Deep neural networks (DNNs) excel in segmentation benchmarks, but it is unclear if they have the ability to solve the insideness problem as it requires evaluating long-range spatial dependencies. In this letter, we analyze the insideness problem in isolation, without texture or semantic cues, such that other aspects of segmentation do not interfere in the analysis. We demonstrate that DNNs for segmentation with few units have sufficient complexity to solve the insideness for any curve. Yet such DNNs have severe problems with learning general solutions. Only recurrent networks trained with small images learn solutions that generalize well to almost any curve. Recurrent networks can decompose the evaluation of long-range dependencies into a sequence of local operations, and learning with small images alleviates the common difficulties of training recurrent networks with a large number of unrolling steps

    "Comparative Study Of The Profiles Of Th1 And Th2 Cytokines In Patients With Sputum Smear- Positive Pulmonary Tuberculosis And PPD–Positive Healthy Persons And Their Changes During Treatment "

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    Background and Aim: The better understanding of immunopathologic mechanism of tuberculosis (TB) is necessary for the production of new vaccines and adjunctive immunomodulator drugs. Intended to this object, the following study including the measurement of serum concentrations of Th1 &amp;#61531;(Interferon (IFN)-y and interkeukin (IL)-2&amp;#61533; and Th2 cytokines(IL-4AND IL-10 ) in patients with sputum smear-positive pulmonary TB and comparisons of them with PPpositive healthy persons, was designed. Materials and Methods: The HIV-negative patients that had sputum smear-positive pulmonary TB as defined WHO criteria and hospitalized in the infectious diseases ward of Imam Khomeini hospital or referred to health care centers in the south of Tehran, were included in the study. The PPD-positive healthy persons who were close contacts with pulmonary TB patients, were considered as control group. Results: In this research 34 active pulmonary TB patients (including17men and 17 woman)and 23 healthy persons with PPD skin test results &amp;#61502; or = 10mm (including 12men and 11 woman) were studied. The mean ages of the patients and the healthy persons were 73 and 41 years and 74 and 27 years, respectively. The mean serum IFN-Y concentration was significantly higher in TB patients but the mean serum IL-2 IL-4and IL-10 concentrations were significantly higher in healthy persons. The com parison of the mean serum levels of these cytokines before and during treatment (about 2 months after starting treatment) showed that the amounts of IFN-y and IL4 were increased and the amounts of IL2 and IL-10 were decreased but only the changes of IL-10 were statistically significant. There were no effect on the cytokine changes before and during treatment by age and gender of the patients. Conclusion: The results of the study of serum Th1 and Th2 cytokines in pulmonary TB patients were different in comparison with the results of the studies of peripheral blood mononuclear cells (PBMCs) stimulated with M.tuberculosis antigens. SO, the simultaneous measurement of them in serum, pleural fluid, BAL fluid and the medium culture of PBMCs stimulated with the antigens is recommended
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