scholarly journals Effect of the Growth Regulator Paclobutrazol on Growth of the Bacterial Pathogen Xylella fastidiosa Xylella fastidiosa

2007 ◽  
Vol 33 (4) ◽  
pp. 246-252
Author(s):  
Darren DeStefano ◽  
Arv Grybauskas ◽  
James Sherald ◽  
Bahram Momen ◽  
Qi Huang ◽  
...  
Keyword(s):  
Direct Effect ◽  
Growth Regulator ◽  
Growth Regulation ◽  
Xylella Fastidiosa ◽  
Bacterial Pathogen ◽  
Colony Growth ◽  
Shade Trees ◽  
Leaf Scorch ◽  
Chronic Disorder

Xylella fastidiosa is a fastidious, xylem-limited, insect-transmitted, bacterial plant pathogen with a wide host range that causes bacterial leaf scorch (BLS) in shade trees. BLS is a chronic disorder characterized by late season leaf scorch and dieback and is common in urban and suburban areas of the mid-Atlantic and southeast United States. BLS has been recognized since the 1980s and attempted treatments have included antibiotics and plant growth regulators. Application of paclobutrazol (PBZ), a diastereomeric triazole with both fungistatic and growth regulation properties, has been observed to alleviate symptoms of BLS, but it has not been established whether PBZ has a direct effect on the organism. In this study, we investigated the effect of PBZ on in vitro growth of two X. fastidiosa isolates. Our results showed no significant effect of PBZ on colony growth of X. fastidiosa at the manufacturers recommended rate of 20 ‘ºg/mL ’àí1. However, significant reductions in bacterial growth were observed at a rate of 200 ‘ºg/mL ’àí1, indicating that high levels of PBZ may have a direct effect on the growth of X. fastidiosa. This direct effect and growth regulator effects of PBZs suggest that PBZ may provide a promising treatment for BLS in shade trees.

scholarly journals Phenotypic and Phylogenetic Characterization of Cu Homeostasis among Xylella fastidiosa Strains

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 495
Author(s):  
Qing Ge ◽  
Ranlin Liu ◽  
Paul A. Cobine ◽  
Neha Potnis ◽  
Leonardo De La Fuente
Keyword(s):  
Core Genome ◽  
Xylella Fastidiosa ◽  
Bacterial Pathogen ◽  
Antimicrobial Treatment ◽  
Plant Diseases ◽  
Phylogenetic Characterization ◽  
Cu Homeostasis ◽  
Geographical Locations

Xylella fastidiosa is a bacterial pathogen causing severe diseases and asymptomatic colonization in more than 600 plants worldwide. Copper (Cu) is a widely used antimicrobial treatment for various plant diseases, including those affecting X. fastidiosa hosts. Cu homeostasis among X. fastidiosa strains from different geographical locations and host species has not been characterized. Here, we assessed minimum inhibitory concentration (MIC) of Cu for 54 X. fastidiosa strains. We observed strain-level variation in MIC values within each subspecies. We hypothesized that these differences could be explained by sequence variation in Cu homeostasis genes. Phylogenies based on copA, copB, copL, and cutC were created using 74 genomes (including 43 strains used in vitro) of X. fastidiosa, showing that the phylogenetic clustering of Cu homeostasis associated with clustering was based on core genome phylogenies, rather than on pattern of MIC. No association was found among Cu MIC, subspecies classification, and host and location of isolation, probably due to uneven and limited group of strains whose genomes are available. Further analysis focused on a subgroup of isolates from Georgia’s vineyards that shared similar Cu-related phenotypes. Further research is needed to better understand the distribution of Cu homeostasis for this pathogen.

scholarly journals Transmission of Xylella fastidiosa through Pecan Rootstock

HortScience ◽  
2006 ◽  
Vol 41 (6) ◽  
pp. 1455-1456 ◽  
Author(s):  
R. S. Sanderlin ◽  
R. A. Melanson
Keyword(s):  
Xylella Fastidiosa ◽  
Early Spring ◽  
Carya Illinoinensis ◽  
In Vitro Cultures ◽  
High Rate ◽  
Significant Source ◽  
Symptom Development ◽  
Leaf Scorch ◽  
Bacterial Leaf Scorch

Xylella fastidiosa Wells et al., the pathogen that causes pecan [Carya illinoinensis (Wangenh.) C. Koch] bacterial leaf scorch disease, was demonstrated to be highly transmissible through graft unions from infected rootstock into new growth developing from scions. Infected rootstocks were obtained by inoculation of pecan seedlings in pots with in vitro cultures of the pathogen. If rootstock infection occurs in nature, transmission of the pathogen into tissue growing from scions could serve as a significant source of introduction of the disease into pecan orchards. Because symptom development in infected trees typically begins in midsummer and grafting takes place in the early spring, it would be difficult to identify infected rootstock before grafting. Commercial pecan growers sometimes attempt to eliminate bacterial leaf scorch from trees by regrafting to other cultivars. The high rate of transmission from infected rootstocks observed in this test and the lack of knowledge of cultivars with resistance to the disease makes this practice ineffective.

scholarly journals Susceptibility of Some Common Pecan Rootstocks to Infection by Xylella fastidiosa

HortScience ◽  
2015 ◽  
Vol 50 (8) ◽  
pp. 1183-1186 ◽  
Author(s):  
Randy S. Sanderlin
Keyword(s):  
Xylella Fastidiosa ◽  
Bacterial Pathogen ◽  
The United States ◽  
Hot Water ◽  
Broad Host Range ◽  
Mechanical Inoculation ◽  
Leaf Scorch ◽  
Susceptibility To Infection ◽  
Resistance To Infection ◽  
Cape Fear

Pecan [Carya illinoinensis (Wangenh.) K. Koch], a hardwood tree native to North America, is grown for commercial production of nuts in southeastern, central, and western regions of the United States. Pecan is also grown commercially in Mexico, South Africa, Australia, and some countries in South America. Pecan trees can be infected by the broad host range xylem-limited bacterial pathogen Xylella fastidiosa Wells et al. Infection incites a leaf scorch disease that can cause significant defoliation, reduced tree growth, and lower nut yield. Pecan cultivars are clonally propagated onto rootstocks grown from open-pollinated seed of selected cultivars. X. fastidiosa is transmitted at a high frequency from infected rootstocks into newly developing grafted trees. Rootstocks resistant to infection would be beneficial to pecan nurseries and pecan producers to prevent infection of young trees through grafting, especially when combined with hot-water treatment of scions to eliminate the pathogen. Some common rootstocks were tested for variation in susceptibility to infection using mechanical inoculation with the pathogen. No outstanding level of resistance to infection was detected among the seven rootstocks tested. The rootstocks from ‘Curtis’, ‘Elliott’, and ‘Riverside’ were less susceptible than one standard rootstock in the test (‘VC1-68’) and less susceptible than highly susceptible ‘Cape Fear’ rootstock. Conversely, the rootstocks from ‘Apache’, ‘Moore’, ‘Stuart’, and ‘VC1-68’ seed had a level of susceptibility to infection comparable to ‘Cape Fear’ and perhaps are not the best choice for rootstocks in geographic areas where X. fastidiosa is prevalent. The results of this research suggest that there is variation in rootstock susceptibility to infection by X. fastidiosa. The use of mechanical inoculation may facilitate identification of susceptibility categories of pecan rootstocks to the pecan bacterial leaf scorch pathogen.

scholarly journals Epidemiology of Diseases Caused by Xylella fastidiosa in California: Evaluation of Alfalfa as a Source of Vectors and Inocula

Plant Disease ◽  
2010 ◽  
Vol 94 (7) ◽  
pp. 827-834 ◽  
Author(s):  
Mark S. Sisterson ◽  
Shyamala R. Thammiraju ◽  
Kris Lynn-Patterson ◽  
Russell L. Groves ◽  
Kent M. Daane
Keyword(s):  
Information Systems ◽  
Geographic Information Systems ◽  
Xylella Fastidiosa ◽  
Bacterial Pathogen ◽  
Geographic Information ◽  
Seasonal Trends ◽  
Leaf Scorch ◽  
Alfalfa Field ◽  
Winter Temperatures ◽  
Almond Leaf Scorch

Pierce's disease and almond leaf scorch disease have been chronic problems for California grape and almond growers, respectively. Both diseases are caused by the xylem-limited, bacterial pathogen Xylella fastidiosa, which is transmitted by xylem-feeding insects. We evaluated the potential for alfalfa to serve as a source of vectors and inocula in California. Analysis of Geographic Information Systems maps on the distribution and abundance of grape, almond, and alfalfa plantings determined that 94,521 ha of almond and grape were planted within 1.6 km of an alfalfa field. Seasonal trends of X. fastidiosa detection were monitored outdoors and in the greenhouse in five needle-inoculated alfalfa cultivars (CUF101, Moapa69, WL342, WL530HQ, and WL625HQ) over 2 years. Results suggest that cool winter temperatures reduced X. fastidiosa populations to undetectable levels but did not eliminate infections. Sampling of alfalfa fields to assess incidence of X. fastidiosa corroborated this result, with positive samples detected in summer only. Incidence of X. fastidiosa in alfalfa during summer was low, with only 6 positive samples out of 1,156 samples collected over 3 years. Insect trapping in alfalfa fields over 3 years found that the green sharpshooter (Draeculacephala minerva) was the most abundant vector. Within alfalfa fields, green sharpshooter abundance was highest in weedy areas, suggesting a preference for weeds over alfalfa. These results confirm that weedy alfalfa fields can serve as an important source of vectors. Incidence of X. fastidiosa in alfalfa was low, possibly due to preference of vectors for weeds over alfalfa.

Superoxide, Xanthine Oxidase and Platelet Reactions: Further Studies on Mechanisms by which Oxidants Influence Platelets

1981 ◽  
Vol 45 (03) ◽  
pp. 290-293 ◽  
Author(s):  
Peter H Levine ◽  
Danielle G Sladdin ◽  
Norman I Krinsky
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Direct Effect ◽  
Platelet Function ◽  
Experimental Conditions ◽  
Release Reaction

SummaryIn the course of studying the effects on platelets of the oxidant species superoxide (O- 2), Of was generated by the interaction of xanthine oxidase plus xanthine. Surprisingly, gel-filtered platelets, when exposed to xanthine oxidase in the absence of xanthine substrate, were found to generate superoxide (O- 2), as determined by the reduction of added cytochrome c and by the inhibition of this reduction in the presence of superoxide dismutase.In addition to generating Of, the xanthine oxidase-treated platelets display both aggregation and evidence of the release reaction. This xanthine oxidase induced aggreagtion is not inhibited by the addition of either superoxide dismutase or cytochrome c, suggesting that it is due to either a further metabolite of O- 2, or that O- 2 itself exerts no important direct effect on platelet function under these experimental conditions. The ability of Of to modulate platelet reactions in vivo or in vitro remains in doubt, and xanthine oxidase is an unsuitable source of O- 2 in platelet studies because of its own effects on platelets.

First Fluorescent Acetylspermidine Deacetylation Assay for HDAC10 Identifies Inhibitors of Neuroblastoma Cell Colony Growth That Increase Lysosome Accumulation

2020 ◽  
Author(s):  
Daniel Herp ◽  
Johannes Ridinger ◽  
Dina Robaa ◽  
Stephen A. Shinsky ◽  
Karin Schmidtkunz ◽  
...  
Keyword(s):  
Histone Deacetylases ◽  
High Throughput Screening ◽  
Neuroblastoma Cell ◽  
Hdac Inhibitors ◽  
Anticancer Therapy ◽  
Colony Growth ◽  
Autophagic Flux ◽  
Enzymatic Conversion ◽  
Lysine Deacetylase

Histone deacetylases (HDACs) are important epigenetic regulators involved in many diseases, esp. cancer. First HDAC inhibitors have been approved for anticancer therapy and many are in clinical trials. Among the 11 zinc-dependent HDACs, HDAC10 has received relatively little attention by drug discovery campaigns, despite its involvement e.g. in the pathogenesis of neuroblastoma. This is due in part to a lack of robust enzymatic conversion assays. In contrast to the protein lysine deacetylase and deacylase activity of the other HDAC subtypes, it has recently been shown that HDAC10 has strong preferences for deacetylation of oligoamine substrates like spermine or spermidine. Hence, it also termed a polyamine deacetylase (PDAC). Here, we present the first fluorescent enzymatic conversion assay for HDAC10 using an aminocoumarin labelled acetyl spermidine derivative to measure its PDAC activity, which is suitable for high-throughput screening. Using this assay, we identified potent inhibitors of HDAC10 mediated spermidine deacetylation in-vitro. Among those are potent inhibitors of neuroblastoma colony growth in culture that show accumulation of lysosomes, implicating disturbance of autophagic flux.

Kinase Targets for Mycolic Acid Biosynthesis in Mycobacterium tuberculosis

2019 ◽  
Vol 12 (1) ◽  
pp. 27-49 ◽  
Author(s):  
Shahinda S.R. Alsayed ◽  
Chau C. Beh ◽  
Neil R. Foster ◽  
Alan D. Payne ◽  
Yu Yu ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Enzymatic Activity ◽  
Bacterial Pathogen ◽  
Building Blocks ◽  
Mycolic Acid ◽  
Adaptive Responses ◽  
Mycolic Acids ◽  
Hydroxylated Fatty Acids

Background:Mycolic acids (MAs) are the characteristic, integral building blocks for the mycomembrane belonging to the insidious bacterial pathogen Mycobacterium tuberculosis (M.tb). These C60-C90 long α-alkyl-β-hydroxylated fatty acids provide protection to the tubercle bacilli against the outside threats, thus allowing its survival, virulence and resistance to the current antibacterial agents. In the post-genomic era, progress has been made towards understanding the crucial enzymatic machineries involved in the biosynthesis of MAs in M.tb. However, gaps still remain in the exact role of the phosphorylation and dephosphorylation of regulatory mechanisms within these systems. To date, a total of 11 serine-threonine protein kinases (STPKs) are found in M.tb. Most enzymes implicated in the MAs synthesis were found to be phosphorylated in vitro and/or in vivo. For instance, phosphorylation of KasA, KasB, mtFabH, InhA, MabA, and FadD32 downregulated their enzymatic activity, while phosphorylation of VirS increased its enzymatic activity. These observations suggest that the kinases and phosphatases system could play a role in M.tb adaptive responses and survival mechanisms in the human host. As the mycobacterial STPKs do not share a high sequence homology to the human’s, there have been some early drug discovery efforts towards developing potent and selective inhibitors.Objective:Recent updates to the kinases and phosphatases involved in the regulation of MAs biosynthesis will be presented in this mini-review, including their known small molecule inhibitors.Conclusion:Mycobacterial kinases and phosphatases involved in the MAs regulation may serve as a useful avenue for antitubercular therapy.

Angiogenic Effect of Pravastatin Alone and with Sera from Healthy and Complicated Pregnancies Studied by in vitro Vasculogenesis/Angiogenesis Assay

2021 ◽  
pp. 1-9
Author(s):  
Anita Virtanen ◽  
Outi Huttala ◽  
Kati Tihtonen ◽  
Tarja Toimela ◽  
Tuula Heinonen ◽  
...  
Keyword(s):  
Direct Effect ◽  
Late Onset ◽  
Maternal Serum ◽  
In Vitro Assay ◽  
Serum Samples ◽  
Therapeutic Concentration ◽  
Tubule Formation ◽  
Vitro Assay ◽  
Angiogenesis Assay

<b><i>Objective:</i></b> To determine the direct effect of pravastatin on angiogenesis and to study the interaction between pravastatin and maternal sera from women with early- or late-onset pre-eclampsia (PE), intrauterine growth restriction, or healthy pregnancy. <b><i>Methods:</i></b> We collected 5 maternal serum samples from each group. The effect of pravastatin on angiogenesis was assessed with and without maternal sera by quantifying tubule formation in a human-based in vitro assay. Pravastatin was added at 20, 1,000, and 8,000 ng/mL concentrations. Concentrations of angiogenic and inflammatory biomarkers in serum and in test medium after supplementation of serum alone and with pravastatin (1,000 ng/mL) were measured. <b><i>Results:</i></b> Therapeutic concentration of pravastatin (20 ng/mL) did not have significant direct effect on angiogenesis, but the highest concentrations inhibited angiogenesis. Pravastatin did not change the levels of biomarkers in the test media. There were no changes in angiogenesis when therapeutic dose of pravastatin was added with maternal sera, but there was a trend to wide individual variation towards enhanced angiogenesis, particularly in the early-onset PE group. <b><i>Conclusions:</i></b> At therapeutic concentration, pravastatin alone or with maternal sera has no significant effect on angiogenesis, but at high concentrations the effect seems to be anti-angiogenic estimated by in vitro assay.

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