Effect of Benomyl on Chitinase and β-1,3-Glucanase Production by Free and Alginate Encapsulated Trichoderma harzianum

On PDA-benomyl plates growth of Trichoderma harzianum was inhibited by 20 and 30 % at benomyl 1 and 2 μg/mL, respectively, and was completely inhibited at 5 μg/mL. In minimal synthetic medium (MSM) amended with different concentrations of benomyl (1.0, 3.0, 5.0, 7.0 and 10.0 μg/mL), fungal immobilisation improved chitinase and β-1,3-glucanase production at low benomyl concentrations (1, 3 and 5 μg/mL). Further increase in the production of both enzymes was obtained by immobilisation at higher benomyl concentrations (7 and 10 μg/mL). Fungal immobilisation increased bound chitinase by 15- to 30-fold at 3 and 5 μg/mL benomyl concentration, respectively. However, no effect was obtained on the bound β-1,3-glucanase. Different benomyl concentrations (0.3 to 1500 μg/mL) had no significant inhibitory effect on the activities of free or immobilised chitinase and β-1,3-glucanase. It could be suggested that either immobilised Trichoderma or immobilised chitinase and β-1,3-glucanase could be used in combination with benomyl to control plant pathogens

Bacillus subtilis QST 713, copper hydroxide, and their tank mixes for control of bacterial citrus canker in Saudi Arabia

Citrus Bacterial Canker (CBC) is a serious disease that affects production of almost all commercial citrus cultivars in subtropical citrus growing regions worldwide. In this study, the effectiveness of monthly foliar sprays of wettable powder formulation Serenade MAX of Bacillus subtilis QST 713, alone or as tank mixes with copper hydroxide on CBC disease development was evaluated under greenhouse and uncovered nursery conditions. The QST 713 as a tank mix with copper hydroxide reduced significantly the disease severity and incidence, followed by the copper hydroxide treatment, compared to the control. The disease incidence on leaves of inoculated trees treated with a combination of copper with QST 713 was never higher than 19%, whereas, the disease incidence reached 43% for non-sprayed trees. It was possible to reduce the number of copper sprays up to 6 sprays per season when it was mixed with the bio-fungicide QST 713 to effectively control CBC compared with 8 sprays of copper hydroxide alone per season. Based on our results, the application of QST 713 not only may have potential for CBC management in conjunction with copper hydroxide or other disease control but also may reduce the frequency or rate of copper sprays in citrus groves

Potential of resistance inducers for citrus huanglongbing management via soil application and assessment of induction of pathogenesis-related protein genes

Huanglongbing (HLB) or citrus greening currently is the most devastating citrus disease worldwide. Unfortunately, no practical cure has been available up to now. This makes the control of HLB as early as possible very important to be conducted. The objective of this study was to investigate the efficacy of the application of salicylic acid (SA) and Phenylacetic acid (PAA) on one-year-old seedlings of different citrus species (Citrus reticulata, C. sinensis, C. aurantifolii) growing on C. volkameriana and C. aurantium by soil drench methods. Factorial analysis of variance showed the percent change in “Candidatus Liberibacter asiaticus” titer and disease severity on a different combination of citrus species growing on the two rootstocks treated with inducers and Oxytetracycline (OTC) were significantly different compared to the untreated plants. SA alone or in combination with OTC provided excellent (P-value < 0.05) control of HLB based on all parameters. The interaction between both factors (Rootstocks x Citrus species) significantly influenced the Ct value (P-value = 0.0001). “Candidatus Liberibacter asiaticus” titer in plants treated with OTC was reduced significantly with a range of −18.75 up to −78.42. Overall, the highest reduction was observed in the application of OTC on sweet orange growing on C. volkameriana (−78.42), while the lowest reduction was observed in the same cultivar which was treated with a combination of SA and OTC (−3.36). Induction of pathogenesis-related (PR) genes, i.e., PR1, PR2, and PR15, biosynthesis of Jasmonic acid and ethylene which are also important pathways to defense activity were also significantly increased in treated plants compared to untreated plants. This study suggests that the application of inducer alone is acceptable for HLB management. We proposed the application of SA and PAA as a soil drench on the citrus seedlings as promising, easy, and environmentally safe for HLB disease control on citrus seedlings

Differentiation of ‘Candidatus Liberibacter asiaticus’ in Saudi Arabia based on tandem repeat variability in genomic locus

Citrus greening, or huanglongbing, is a destructive disease threatening many citrus worldwide, and drastically altering the global dynamics of the citrus industry. The disease is caused by one of several unculturable bacterial species belonging to ‘Candidatus Liberibacter’. The recent availability of complete genome sequences of ‘Candidatus Liberibacter asiaticus’ (CLas) has facilitated comprehensive assessments of genomic variability using a range of approaches, including short tandem repeat analysis. The objective of this study was to evaluate the genetic diversity of CLas populations in Saudi Arabia based on tandem repeat number (TRN) within the CLIBASIA_01645 locus, predicted to encode the bacteriophage C1 repressor protein. Results indicated that the genotype richness of the Saudi Arabian CLas isolates was conserved by 27% based on the TRN locus. Four different genotypes TRN2, TRN3, TRN4, and TRN5 were identified. However, the TRN2 and TRN5 were the most dominant genotypes. All four of the TRN genotypes were associated with CLas-positive mandarin (Citrus reticulata) or sweet orange (C. sinensis) citrus trees. The diversity (H = 0.69) and evenness (H'=0.914) were overall relatively high, with the northern region of Saudi Arabia harboring the highest diversity (0.7) and evenness score (0.9–1.0). Phylogenetic analysis of the CLas-bacteriophage C1 repressor protein of the Saudi Arabian isolates indicated CLas was more closely related to ‘Candidatus Liberibacter africanus’ than to ‘Candidatus Liberibacter americanus’

Pharmacokinetic Analysis of Continuous Erythropoietin Receptor Activator Disposition in Adult Sheep Using a Target-Mediated, Physiologic Recirculation Model and a Tracer Interaction Methodology

The pharmacokinetics (PK) of continuous erythropoietin receptor activator (CERA), a PEGylated erythropoietin (EPO) derivative, was studied in sheep after bone marrow (BM) busulfan ablation by using a receptor-based recirculation model and tracer interaction method (TIM) experiments. The nontracer CERA component of the TIM was analyzed using a noncompartmental approach. In contrast to EPO elimination that is linear after the BM ablation, CERA elimination remains nonlinear. After busulfan treatment, initial EPO receptors (EPOR) normalized production rate constant, EPOR degradation rate constant, and CERA-EPOR complex internalization rate constant decreased (p < 0.01), whereas no change in CERA/EPOR equilibrium dissociation constant was detected (p > 0.05). After BM ablation, noncompartmental analysis showed that CERA-PK parameters underwent 1) a decrease in plasma clearance (p < 0.01); 2) a concomitant increase in elimination half-life and mean residence time; and 3) no significant change in volume of distribution, distribution half-life, or distributional clearance (p > 0.05). These results suggest that CERA elimination is mediated through saturable hematopoietic and nonhematopoietic EPOR pathways, with possible contribution of another EPOR-independent pathway(s). Compared with the nonhematopoietic EPOR population, the hematopoietic receptors have similar affinity to CERA but are significantly more involved in CERA's in vivo elimination. The saturable nature of the nonerythropoietic, non-BM pathway(s) for CERA in contrast to EPO predicts two fundamental differences: 1) an increasing fraction of CERA is used for erythropoiesis for increasing concentrations; and 2) the clearance of CERA becomes more limited for increasing concentrations. Taken together, these differences favor a more efficacious and prolonged action for CERA

Downregulation of interleukin 36γ and its cleaver cathepsin G following treatment with narrow-band ultraviolet B phototherapy in psoriasis vulgaris

Background Growing evidence suggests the important role of IL-36 in the pathogenesis of psoriasis. Cathepsin G is a neutrophil-derived protease that can activate IL-36γ. Objective To assess the expression of IL-36γ and cathepsin G in psoriasis and to quantify the impact of treatment with narrow-band ultraviolet B phototherapy (NB-UVB) on their levels. Methods This case-control study involved 26 patients with moderate-severe psoriasis and 25 healthy volunteers. Psoriasis patients eligible for phototherapy received 24 NB-UVB sessions. Punch skin biopsies were obtained from all participants at recruitment and after phototherapy from patients. Real-time PCR was utilized for quantitative assessment of IL-36γ and cathepsin G expression in tissue samples. Results The expression of IL-36γ and cathepsin G was significantly higher in psoriasis before NB-UVB therapy compared to controls (p < .001). Both proteins decreased significantly with clinical improvement following NB-UVB therapy compared to baseline (p < .001). However, their expression after treatment was still higher than controls (p < .001). Conclusion IL-36γ and cathepsin G expression is upregulated in psoriatic lesions, supporting their role as mediators of inflammation in psoriasis. Downregulation of IL-36γ and cathepsin G is a possible mechanism for psoriasis improvement after NB-UVB therapy. IL-36 and cathepsin G can be considered as therapeutic targets for psoriasis

Characterization of the Asian Citrus Psyllid-‘<i>Candidatus</i> Liberibacter Asiaticus’ Pathosystem in Saudi Arabia Reveals Two Predominant CLas Lineages and One Asian Citrus Psyllid Vector Haplotype

In Saudi Arabia (SA), the citrus greening disease is caused by ‘Candidatus Liberibacter asiaticus’ (CLas) transmitted by the Asian citrus psyllid (ACP) Diaphorina citri. The origin and route(s) of the ACP-CLas pathosystem invasion in SA have not been studied. Adult ACP were collected from citrus trees in SA and differentiated by analysis of the mitochondrial cytochrome oxidase I (mtCOI) and nuclear copper transporting protein (atox1) genes. A phylogenetic analysis of the Wolbachia spp. surface protein (wsp) gene was used to identify the ACP-associated Wolbachia spp. A phylogenetic analysis of the atox1 and mtCOI gene sequences revealed one predominant ACP haplotype most closely related to the Indian subcontinent founder populations. The detection and identification of CLas in citrus trees were carried out by polymerase chain reaction (PCR) amplification and sequencing of the 16S rDNA gene. The CLas-integrated prophage genomes were sequenced, annotated, and used to differentiate CLas populations. The ML and ASTRAL trees reconstructed with prophages type 1 and 2 genome sequences, separately and concatenated, resolved two major lineages, CLas-1 and -2. The CLas-1 clade, reported here for the first time, consisted of isolates from SA isolates and Pakistan. The CLas-2 sequences formed two groups, CLas-2-1 and -2-2, previously the ‘Asiatic’ and ‘Floridian’ strains, respectively. Members of CLas-2-1 originated from Southeast Asia, the USA, and other worldwide locations, while CLas-2-2 was identified only in Florida. This study provides the first snapshot into the status of the ACP-CLas pathosystem in SA. In addition, the results provide new insights into the pathosystem coevolution and global invasion histories of two ACP-CLas lineages with a predicted center of origin in South and Southeast Asia, respectively

2,2′,3,5′,6-Pentachlorobiphenyl (PCB 95) and Its Hydroxylated Metabolites Are Enantiomerically Enriched in Female Mice

Epidemiological and laboratory studies link polychlorinated biphenyls and their metabolites to adverse neurodevelopmental outcomes. Several neurotoxic PCB congeners are chiral and undergo enantiomeric enrichment in mammalian species, which may modulate PCB developmental neurotoxicity. This study measures levels and enantiomeric enrichment of PCB 95 and its hydroxylated metabolites (OH-PCBs) in adult female C57Bl/6 mice following subchronic exposure to racemic PCB 95. Tissue levels of PCB 95 and OH-PCBs increased with increasing dose. Dose-dependent enantiomeric enrichment of PCB 95 was observed in brain and other tissues. OH-PCBs also displayed enantiomeric enrichment in blood and liver, but were not detected in adipose and brain. In light of data suggesting enantioselective effects of chiral PCBs on molecular targets linked to PCB developmental neurotoxicity, our observations highlight the importance of accounting for PCB and OH-PCB enantiomeric enrichment in the assessment of PCB developmental neurotoxicity