Proteomic profiling of clinical and environmental strains of Pseudomonas aeruginosa

Molecular Biology Reports - Pseudomonas aeruginosa is a ubiquitous bacterium, which is able to change its physiological characteristics in response to different habitats. Environmental strains are...     

Antifeedant activity of numb and salty taste compounds against the larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Helicoverpa armigera, an important polyphagous insect pest in agriculture, attacks more than 200 plant species of more than 30 families. Our previous study showed that the choice feeding percentages of H. armigera larvae to tobacco leaf discs treated with sweet, bitter, and hot taste substances were higher than the control leaf discs, while numb and salty substances could significantly inhibit their feeding. To quantitatively determine the synergistic effect of numb and salty substances, in this paper, the antifeeding activities of numb and salty substances and their mixtures blended in different doses or volume ratios were assayed on H. armigera larvae. The first bioassay was designed to elucidate the relative feeding preference of the larvae to the leaves from several common host species, each paired with tobacco leaf discs, and the result indicated that the most preferred host leaf by the larvae was tobacco leaf, followed by cotton and peanut leaves, suggesting that tobacco leaf was the most suitable matrix for the antifeeding bioassay, and the larval consumption of maize, pepper, or tomato leaves were significantly lower than that of tobacco leaf. The second bioassay was to test the choice feeding response of H. armigera larvae to tobacco leaf discs treated with Zanthoxylum bungeanum extracts obtained with different solvents, and the result showed that the antifeeding activity of the alcohol extracts was the strongest (93.38%), and the leaf consumption in the treatment and the control showed extremely significant difference (t = 4.23, t_0.01 = 3.25, P = 0.0022), followed by the dichloromethane extracts (47.64%), while the other three solvents (water, acetone, and n-hexane) could not extract the active antifeeding components from Z. bungeanum. The larval consumption of tobacco leaf discs treated with the alcohol extracts of Z. bungeanum and NaCl solution were significantly less than their corresponding controls. The mean larval consumption of the treated leaf discs decreased with ever-increasing dosage, and the consumption of tobacco leaf discs coated with different doses of alcohol extracts of Z. bungeanum or NaCl solution showed extremely significant difference (F_{alcohol extract of Z. bungeanum} = 3.88, F_0.01 = 3.58, P = 0.0064; F_{NaCl solution} = 54.29, F_0.01 = 3.58, P = 0.0000), with maximum antifeeding effects at a dosage of 30 μL per 1.5 cm ID leaf disc. We further tested the larval consumption of tobacco leaf discs treated with alcohol extracts of Z. bungeanum in saturated NaCl solution mixed in different volume ratios, and the result showed that the choice antifeeding percentages of the treatments with 15 μL or more Z. bungeanum alcohol extracts were higher than 90%, among which the mixture with 25:15 volume ratio of Z. bungeanum alcohol extracts and saturated NaCl solution exhibited the strongest antifeeding activity, and the mean consumed leaf area of tobacco leaf discs coated with this blend was only 0.10 mm². In the further test on feeding dose-response of the 25:15 mixture, the mean leaf consumption decreased linearly with ever-increasing dosage, with a regression equation y = ?3.9356x + 120.78(R² = 0.9998), and the 30 μL dose could completely inhibit H. armigera feeding.     

Malaria Hotspots Drive Hypoendemic Transmission in the Chittagong Hill Districts of Bangladesh

Background

Malaria is endemic in 13 of 64 districts of Bangladesh, representing a population at risk of about 27 million people. The highest rates of malaria in Bangladesh occur in the Chittagong Hill Districts, and Plasmodium falciparum (predominately chloroquine resistant) is the most prevalent species.

Methods

The objective of this research was to describe the epidemiology of symptomatic P. falciparum malaria in an area of Bangladesh following the introduction of a national malaria control program. We carried out surveillance for symptomatic malaria due to P. falciparum in two demographically defined unions of the Chittagong Hill Districts in Bangladesh, bordering western Myanmar, between October 2009 and May 2012. The association between sociodemographics and temporal and climate factors with symptomatic P. falciparum infection over two years of surveillance data was assessed. Risk factors for infection were determined using a multivariate regression model.

Results

472 cases of symptomatic P. falciparum malaria cases were identified among 23,372 residents during the study period. Greater than 85% of cases occurred during the rainy season from May to October, and cases were highly clustered geographically within these two unions with more than 80% of infections occurring in areas that contain approximately one-third of the total population. Risk factors statistically associated with infection in a multivariate logistic regression model were living in the areas of high incidence, young age, and having an occupation including jhum cultivation and/or daily labor. Use of long lasting insecticide-treated bed nets was high (89.3%), but its use was not associated with decreased incidence of infection.

Conclusion

Here we show that P. falciparum malaria continues to be hypoendemic in the Chittagong Hill Districts of Bangladesh, is highly seasonal, and is much more common in certain geographically limited hot spots and among certain occupations.     

Three colorimetric and off–on fluorescent chemosensors for Fe3+ in aqueous media

Three Rhodamine B derivatives were synthesized and characterized by ESI‐MS, NMR, HR‐MS and IR. The probes exhibit high selectivity and sensitivity towards Fe³⁺ over other metal ions in CH₃CN–water. Upon the addition of Fe³⁺, the spirocyclic ring of the probe was opened and a significant enhancement of visible color and fluorescence within the range of 540–700 nm was observed. The colorimetric and fluorescent response to Fe³⁺ can be conveniently detected even by the naked eye, which provides a facile method for the visual detection of Fe³⁺. Job's plot, fluorescence titration and MS indicated the formation of 1:2 complexes between the probes and Fe³⁺. The reversibility of the reaction establishes the potential of these probes as chemosensors for Fe³⁺ detection. Copyright © 2013 John Wiley & Sons, Ltd.     

microRNAs in Circulation Are Altered in Response to Influenza A Virus Infection in Humans

Changes in microRNA expression have been detected in vitro in influenza infected cells, yet little is known about them in patients. microRNA profiling was performed on whole blood of H1N1 patients to identify signature microRNAs to better understand the gene regulation involved and possibly improve diagnosis. Total RNA extracted from blood samples of influenza infected patients and healthy controls were subjected to microRNA microarray. Expression profiles of circulating microRNAs were altered and distinctly different in influenza patients. Expression of highly dysregulated microRNAs were validated using quantitative PCR. Fourteen highly dysregulated miRNAs, identified from the blood of influenza infected patients, provided a clear distinction between infected and healthy individuals. Of these, expression of miR-1260, -26a, -335*, -576-3p, -628-3p and -664 were consistently dysregulated in both whole blood and H1N1 infected cells. Potential host and viral gene targets were identified and the impact of microRNA dysregulation on the host proteome was studied. Consequences of their altered expression were extrapolated to changes in the host proteome expression. These highly dysregulated microRNAs may have crucial roles in influenza pathogenesis and are potential biomarkers of influenza.     

Characterization and Molecular Mechanism of AroP as an Aromatic Amino Acid and Histidine Transporter in Corynebacterium glutamicum

Corynebacterium glutamicum is equipped with abundant membrane transporters to adapt to a changing environment. Many amino acid transporters have been identified in C. glutamicum, but histidine uptake has not been investigated in detail. Here, we identified the aromatic amino acid transporter encoded by aroP as a histidine transporter in C. glutamicum by a combination of the growth and histidine uptake features. Characterization of histidine uptake showed that AroP has a moderate affinity for histidine, with a K_m value of 11.40 ± 2.03 μM, and histidine uptake by AroP is competitively inhibited by the aromatic amino acids. Among the four substrates, AroP exhibits a stronger preference for tryptophan than for tyrosine, phenylalanine, and histidine. Homology structure modeling and molecular docking were performed to predict the substrate binding modes and conformational changes during substrate transport. These results suggested that tryptophan is best accommodated in the binding pocket due to shape compatibility, strong hydrophobic interactions, and the lowest binding energy, which is consistent with the observed substrate preference of AroP. Furthermore, the missense mutations of the putative substrate binding sites verified that Ser24, Ala28, and Gly29 play crucial roles in substrate binding and are highly conserved in the Gram-positive bacteria. Finally, the expression of aroP is not significantly affected by extracellular histidine or aromatic amino acids, indicating that the physiological role of AroP may be correlated with the increased fitness of C. glutamicum to assimilate extracellular amino acid for avoiding the high energy cost of amino acid biosynthesis.