Isolation and characterization of pectolytic bacterial pathogens infecting potatoes in Nakuru County, Kenya

AIMS

Isolation and characterization of pectolytic bacteria associated with soft rot disease of potatoes in Nakuru, Kenya, to provide the basis for the development of disease control measures.

METHODS AND RESULTS

Potato tubers showing symptoms of soft rot were collected from different farms in Molo and Mau Narok regions within Nakuru county. Isolation was done using crystal violet pectate medium (CVPM). Out of the 71 isolates that showed growth on CVPM, pathogenicity tests revealed that 36 of them had the ability to macerate tissues of potato tubers. All the isolates yielded a fragment of approximately 1500 bp after 16S rDNA amplification. Using the BIOLOG microbial identification system, 20 bacterial isolates were identified as Pectobacterium carotovorum subsp. carotovorum, 7 were Pseudomonas fluorescens B while 9 were Ps. fluorescens A. Y1/Y2 primers successfully amplified pectate lyase-encoding (pel) gene, approximately 434 bp, in all the 20 P. carotovorum species. The virulence of the isolated strains to cause disease, according to pectinolytic tests, varied with change in incubation temperature of the test samples. Pectobacterium carotovorum strains were the most virulent at 30°C while disease severity due to infection by Ps. fluorescens A strains was high at 20°C compared to the other isolates.

CONCLUSION

This study reveals the identity of pectolytic bacterial species from two genera, Pectobacterium and Pseudomonas, as causative agents of potato soft rot in Nakuru, Kenya.

SIGNIFICANCE AND IMPACT OF THE STUDY

Research findings from this study will aid in developing suitable risk mitigation methods for adoption by farmers to prevent losses due to soft rot.

[Study on relationship between Set gene expression and clinical manifestations in bone marrow of patients with acute myelogenous leukemia]

Objective: To explore the expression and significance of Set gene in Acute myeloid leukemia (AML) patients , and to analyze its effect for the prognosis of AML. Methods: The level of Set gene expression was detected by real-time PCR in 59 AML patients and 20 heathy people. The mutations in C-kit 8/17 gene, NPM1 gene and FLT3-TKD/ITD gene in 59 AML patients were detected by direct sequencing. Results: The level of Set gene expression[1.41(0.41-3.31)]was significantly higher in 59 AML patients.The expression of Set gene was correlated with the percentage of marrow blasts and CR in AML patients (P=0.040, P<0.001); the CR rate of Set gene high expression group was significantly lower than that of Set gene low expression group(32.1% vs 83.9%, P=0.01). In the intermediate-risk of AML patients with chromosome karyotype analysis, the CR rate of Set gene high expression group and low expression group were 34.8% and 88.9%, and there are significantly different between two groups(P<0.001); univariate and multivariate analysis showed that Set gene high expression group correlated with poor OS[4(2-15)months]and EFS[3(2-13)months])(P=0.021, P=0.017). It suggests that the Set gene maybe one of AML independent poor prognostic marker.The level of Set gene expression did not correlate with sex, age, WBC, HGB, PLT, FAB typing, chromosomal karyotype and NPM1, C-Kit8/17, CEBPa, FLT3-ITD/TKD gene mutations in AML patients(all P>0.05). Conclusions: The level of Set gene expression in bone marrow maybe play an important role in AML. The high expression of Set gene indicates poor prognosis in AML patients.

Baicalin inhibits Escherichia coli isolates in bovine mastitic milk and reduces antimicrobial resistance

In this study, we aimed to evaluate the inhibitory effect of baicalin on Escherichia coli in vitro and the effects of baicalin treatment on antimicrobial resistance of the E. coli isolates. Through isolation, purification, and identification, a total of 56 E. coli strains were isolated from 341 mastitic milk samples. The study of inhibition effect of baicalin on the E. coli strains in vitro was focused on permeability and morphology of the isolates using an alkaline phosphatase kit and scanning electron microscopy. Furthermore, the resistance spectrum of the isolates to the common antimicrobial agents was tested at sub-minimum inhibitory concentrations of baicalin by the agar dilution method. Extended-spectrum β-lactamase and plasmid-mediated quinolone resistance genes were amplified by PCR before and after incubation with baicalin. The results revealed that baicalin has certain inhibitory effects on the isolates in vitro. The alkaline phosphatase enzyme activity was significantly increased from 1.246 to 2.377 U/100 mL, and the surface of E. coli was concave and shriveled. Analysis of the resistance spectrum and PCR amplification showed that, after administration with baicalin, the sensitivity of most strains to the selected antimicrobial agents was enhanced. Strikingly, the drug-resistant genes from 71.43% (40/56) of these isolates were found to have drug-resistant genes to different extents. Altogether, the current study confirmed both the inhibitory effect on Escherichia coli in vitro and the reduction of antimicrobial resistance by baicalin. This is the first comprehensive study to report on baicalin, a traditional Chinese medicine that acts on E. coli isolated from the mastitic milk samples.

Role of fibroblast growth factor receptors (FGFR) and FGFR like-1 (FGFRL1) in mesenchymal stromal cell differentiation to osteoblasts and adipocytes

Fibroblast growth factors (FGF) and their receptors (FGFRs) regulate many developmental processes including differentiation of mesenchymal stromal cells (MSC). We developed two MSC lines capable of differentiating to osteoblasts and adipocytes and studied the role of FGFRs in this process. We identified FGFR2 and fibroblast growth factor receptor like-1 (FGFRL1) as possible actors in MSC differentiation with gene microarray and qRT-PCR. FGFR2 and FGFRL1 mRNA expression strongly increased during MSC differentiation to osteoblasts. FGF2 treatment, resulting in downregulation of FGFR2, or silencing FGFR2 expression with siRNAs inhibited osteoblast differentiation. During adipocyte differentiation expression of FGFR1 and FGFRL1 increased and was down-regulated by FGF2. FGFR1 knockdown inhibited adipocyte differentiation. Silencing FGFR2 and FGFR1 in MSCs was associated with decreased FGFRL1 expression in osteoblasts and adipocytes, respectively. Our results suggest that FGFR1 and FGFR2 regulate FGFRL1 expression. FGFRL1 may mediate or modulate FGFR regulation of MSC differentiation together with FGFR2 in osteoblastic and FGFR1 in adipocytic lineage.

A comparative study of low energy radiation response of AlAs, GaAs and GaAs/AlAs superlattice and the damage effects on their electronic structures

In this study, the low energy radiation responses of AlAs, GaAs and GaAs/AlAs superlattice are simulated and the radiation damage effects on their electronic structures are investigated. It is found that the threshold displacement energies for AlAs are generally larger than those for GaAs, i.e., the atoms in AlAs are more difficult to be displaced than those in GaAs under radiation environment. As for GaAs/AlAs superlattice, the Ga and Al atoms are more susceptible to the radiation than those in the bulk AlAs and GaAs, whereas the As atoms need comparable or much larger energies to be displaced than those in the bulk states. The created defects are generally Frenkel pairs, and a few antisite defects are also created in the superlattice structure. The created defects are found to have profound effects on the electronic properties of GaAs/AlAs superlattice, in which charge transfer, redistribution and even accumulation take place, and band gap narrowing and even metallicity are induced in some cases. This study shows that it is necessary to enhance the radiation tolerance of GaAs/AlAs superlattice to improve their performance under irradiation.

[Value of split hand in the differential diagnosis of amyotrophic lateral sclerosis and cervical spondylotic amyotrophy]

Objective: To investigate the value of split hand in the differential diagnosis of amyotrophic lateral sclerosis(ALS) and cervical spondylotic amyotrophy (CSA). Methods: A total of 62 ALS patients, 57 CSA patients and 65 normal controls who visited the Neurology and Spine Department of Beijing Jishuitan Hospital from May 2013 to June 2017 were enrolled into this study.The amplitudes of compound muscle action potentials (CMAP) were recorded from abductor digiti minimi (ADM) and abductor pollicis brevis (APB). Moreover, the ratio of CMAP amplitude between ADM and APB (ADM/APB) was calculated. Results: The ADM/APB of the ALS group (1.93±1.97)was significantly higher than that of the normal control group (0.92±0.22)(P<0.05); the ADM/APB of the CSA group (0.74±0.32)was significantly lower than that of the normal control group (0.92±0.22)(P<0.05); the ADM/APB of the ALS group (1.93±1.97)was significantly higher than that of the CSA group(0.74±0.32)(P<0.05); the areas under receiver operator characteristic curve in patients with ALS was 0.843, the diagnostic sensitivity and specificity for ALS were 75.8% and 83.1% with the cutoff value of ADM/APB=1.077; the areas under receiver operator characteristic curve in patients with CSA was 0.737, the diagnostic sensitivity and specificity for CSA were 64.9% and 87.1% with the cutoff value of ADM/APB=0.739. Conclusion: The ADM/APB has certain clinical value for the differentiation of ALS and CSA.

Expression of IFNAR1 and IFNAR2 in cattle placenta during early pregnancy

Interferon-tau (IFNT), a type I interferon, is an antiluteolytic factor secreted by trophoderm during pregnancy. IFNT transmitted signals or stimulated the expression of some factors to build maternal recognition and keep pregnancy by binding its receptors, IFNT receptor 1(IFNAR1) and IFNT receptor 2 (IFNAR2). Up to now, the expression model and roles of IFNAR1 and IFNAR2 in placenta have not been investigated in cattle. In this study, the localization and expression of IFNAR1 and IFNAR2 in the cattle placenta at days 18-50 of pregnancy were detected by histological examination, immunofluorescence staining and real-time qPCR. The results showed that IFNAR1 mainly distributed in chorioallantoic membrane, endometrial epithelium, cotyledon and caruncle during the early pregnancy of cattle with change in time- and position-dependent. IFNAR1 and IFNAR2 mRNA expression were mainly detected in chorioallantoic membrane and cotyledon, and markedly increased along with pregnancy process. Moreover, the mRNA expression level of IFNAR1 in chorioallantoic membrane and cotyledon was higher than that of IFNAR2. IFNAR mRNA was also expressed in caruncle tissues, which experienced a tendency of decrease from days 21 to 36, followed by increase after days 36. These results provide morphological basis and quantitative data for investigating the roles of IFNAR1 and IFNAR2 on development of cattle placenta and pregnancy maintenance.

Tunneling anisotropic magnetoresistance driven by magnetic phase transition

The independent control of two magnetic electrodes and spin-coherent transport in magnetic tunnel junctions are strictly required for tunneling magnetoresistance, while junctions with only one ferromagnetic electrode exhibit tunneling anisotropic magnetoresistance dependent on the anisotropic density of states with no room temperature performance so far. Here, we report an alternative approach to obtaining tunneling anisotropic magnetoresistance in α′-FeRh-based junctions driven by the magnetic phase transition of α′-FeRh and resultantly large variation of the density of states in the vicinity of MgO tunneling barrier, referred to as phase transition tunneling anisotropic magnetoresistance. The junctions with only one α′-FeRh magnetic electrode show a magnetoresistance ratio up to 20% at room temperature. Both the polarity and magnitude of the phase transition tunneling anisotropic magnetoresistance can be modulated by interfacial engineering at the α′-FeRh/MgO interface. Besides the fundamental significance, our finding might add a different dimension to magnetic random access memory and antiferromagnet spintronics.

Tunneling anisotropic magnetoresistance is promising for next generation memory devices but limited by the low efficiency and functioning temperature. Here the authors achieved 20% tunneling anisotropic magnetoresistance at room temperature in magnetic tunnel junctions with one α′-FeRh magnetic electrode.

Impact of isovalent and aliovalent substitution on the mechanical and thermal properties of Gd2Zr2O7

In this study, a density functional theory method is employed to investigate the effects of isovalent and aliovalent substitution of Sm³⁺ on the phase stability, thermo-physical properties and electronic structure of Gd₂Zr₂O₇. It is shown that the isovalent substitution of Sm³⁺ for Gd³⁺ results in the formation of Gd₂Zr₂O₇-Sm₂Zr₂O₇ solid solution, which retains the pyrochlore structure and has slight effects on the elastic moduli, ductility, Debye temperature and band gap of Gd₂Zr₂O₇. As for the aliovalent substitution of Sm³⁺ for Zr⁴⁺ site, a pyrochlore-to-defect fluorite structural transition is induced, and the mechanical, thermal properties and electronic structures are influenced significantly. As compared with the Gd₂Zr₂O₇, the resulted Gd₂Sm_yZr_2-yO₇ compositions have much smaller elastic moduli, better ductility and smaller Debye temperature. Especially, an amount of electrons distribute on the fermi level and they are expected to have larger thermal conductivity than Gd₂Zr₂O₇. This study suggests an alternative way to engineer the thermo-physical properties of Gd₂Zr₂O₇ and will be beneficial for its applications under stress and high temperature.

Geographical variation and the role of climate in leaf traits of a relict tree species across its distribution in China

Intraspecific trait variation and trait-climate relationships are crucial for understanding a species' response to climate change. However, these phenomena have rarely been studied for tree species. Euptelea pleiospermum is a relict tree species with a wide distribution in China that offers a novel opportunity to examine such relationships. Here, we measured 13 leaf traits of E. pleiospermum in 20 sites across its natural distribution in China. We investigated the extent of trait variation at local and regional scales, and developed geographic and climate models to explain trait variation at the regional scale. We documented intraspecific trait variation among leaf traits of E. pleiospermum at local and regional scales. Five traits exhibited relatively high trait variation: leaf area, leaf density and three leaf economic traits (leaf dry matter content, specific leaf area [SLA] and leaf phosphorus concentration). Significant trait-geography correlations were mediated by local climate. Most leaf trait variation could be explained (from 24% to 64%) by geographic or climate variables, except leaf width, leaf thickness, leaf dry matter content and leaf length-width ratio. Latitude and temperature were the strongest predictors of trait variation throughout the distribution of E. pleiospermum in China, and temperature explained more leaf trait variation than precipitation. In particular, we showed that leaves had longer petiole lengths, higher SLA and lower densities in northern E. pleiospermum populations. We suggest that northern E. pleiospermum populations are adapting to higher latitudinal environments via high growth rate (higher SLA) and low construction investment strategies (lower leaf densities), benefitting northern migration. Overall, we demonstrate that intraspecific trait variation reflects E. pleiospermum response to the local environment. We call for consideration of intraspecific trait variation to examine specific climate response questions. In addition, provenance experiments using widely distributed species are needed to separate trait variation resulting from genetic differentiation and plastic responses to environmental change.

Ab initio molecular dynamics simulation of low energy radiation responses of α-Al2O3

In this study, an ab initio molecular dynamics method is employed to investigate the response behavior of α-Al2O3 to low energy irradiation. Different from the previous experiments, our calculations reveal that the displacements of oxygen dominate under electron irradiation and the created defects are mainly oxygen vacancy and interstitial. The experimental observation of the absorption peaks appearing at 203, 233 and 256 nm for α-Al2O3 under electron irradiations should be contributed by the oxygen defects and these defects will reduce the transmittance of α-Al2O3, which agrees well with the very recent experiment. This study demonstrates the necessity to reinvestigate the threshold displacement energies of α-Al2O3, and to introduce recombination center for oxygen defects to improve its optical properties and performance under radiation environment.

Hypertrophic cardiomyopathy and left ventricular hypertrophy in hypertensive heart disease with mildly reduced or preserved ejection fraction: insight from altered mechanics and native T1 mapping

AIM

To explore the relationship between extracellular volume (ECV), native T1, and systolic strain in hypertrophic cardiomyopathy (HCM) and hypertensive patients with left ventricular hypertrophy (HTN LVH) with mildly reduced or preserved ejection fraction.

MATERIALS AND METHODS

T1 mapping was performed in 45 patients with late gadolinium enhancement positive (LGE+) HCM (mean age, 53±6 years), 11 patients with LGE- (LGE-) HCM (mean age, 56±5 years), and 20 patients with HTN LVH (mean age, 55±6 years) on at 3 T magnetic resonance imaging (MRI) using the modified look-locker inversion-recovery (MOLLI) pulse sequence. Mean T1 value, ECV and circumferential strain parameters were determined for each patient.

RESULTS

Overall, the HCM patients had higher native T1 values (1242.92±68.94) and ECV (0.31±0.05) in comparison to those of the HTN LVH patients (1197±46.80, 0.27±0.04; p<0.05). In the subgroup analysis, the HCM LGE+ patients had the highest native T1 values among the three groups. The HCM LGE+ patients had higher ECV than the LGE- patients. HCM LGE- patients had higher ECV than HTN LVH patients (p<0.05). Peak systolic circumferential strain and early diastolic strain rates were reduced in the HCM LGE+ patients in comparison to the HCM LGE- and HTN LVH patients (p<0.05). Reduced peak systolic and early diastolic circumferential strain rates were associated with increased levels of ECV and native T1 values among all the patients.

CONCLUSION

HCM LGE+ patients had higher native T1 values, higher ECV, and an associated reduction in early diastolic strain rates and peak systolic circumferential strains when compared to the HCM LGE- and HTN LVH patients with mildly reduced or preserved ejection fraction.

MicroRNA-195 inhibits human gastric cancer by directly targeting basic fibroblast growth factor

PURPOSE

Gastric cancer (GC) is one of the fatal malignancies worldwide with high occurrences but poor outcomes. bFGF has been shown to play significant roles in GC. Yet, whether bFGF affects the development of GC is less studied.

METHODS

MicroRNA assays, real-time PCR, and western blot were conducted for expression analysis of miR-195-5p and basic fibroblast growth factor (bFGF). Luciferase activity was measured with mutated bFGF 3'-UTR sequence at the 3' end of the luciferase gene. Two GC cell lines, SNU-1 and KATO-3 overexpressing miR-195-5p and bFGF were subjected to wound healing assay and transwell invasion assay. Mouse GC xenograft model was established and subjected to tumor size analysis.

RESULTS

Expression levels of miR-195-5p and bFGF showed negative correlation in human GC tissues. MiR-195-5p directly targeted bFGF 3'-UTR as demonstrated by luciferase activity assay. MiR-195-5p, through downregulating bFGF, inhibited the migration and invasion of SNU-1 and KATO-3 cells, as well as tumorigenesis in a xenograft mouse model, which could be restored by re-introduction of bFGF.

CONCLUSIONS

MiR-195-5p inhibits tumorigenesis of GC through suppressing bFGF, which supports both miR-195-5p and bFGF as potential therapeutic targets in the treatment of GC.