Baseline susceptibility of Asian corn borer (Ostrinia furnacalis (Guenée)) populations in Vietnam to Cry1Ab insecticidal protein

Susceptibility of Asian corn borer (ACB), Ostrinia furnacalis (Guenée) to Bacillus thuringiensis (Bt) Cry1Ab protein was studied between 2015 and 2016 with 11 ACB populations, collected from various geographical regions in Vietnam. A concentration range of Cry1Ab from 0.20 to 26.10 ng/cm² of diet was evaluated against F₁ ACB neonates using diet surface-overlay bioassays. Mortality data was recorded daily until seven days after infestation. Growth inhibition was recorded at the end of seven days. The median lethal concentration (LC₅₀) varied ≈3-fold among the different populations, ranging from 0.58 to 1.83 ng/cm² of diet with an overall mean of 0.86 ng/cm² of diet. Even the lowest concentration of 0.20 ng/cm² caused 73.53% growth inhibition. >90% growth inhibition was achieved at 0.82 ng/cm² or higher concentrations. The results reflect natural variation in Bt susceptibility among ACB populations rather than variation caused by prior exposure to selection pressures. LC₉₉ value (17.26 ng/cm²) was generated by pooling mortality data across different populations. The upper fiducial limit of LC₉₉ (24.38 ng/cm²) could be a potential diagnostic dose for future resistance monitoring programs. The findings from this study suggest that ACB populations in Vietnam are highly susceptible to Cry1Ab protein. This is the first report of Cry1Ab susceptibility of different ACB populations in Vietnam and will serve as a baseline for future resistance monitoring work.     

Polysaccharide intercellular adhesin (PIA) protects Staphylococcus epidermidis against major components of the human innate immune system

The skin commensal and opportunistic pathogen Staphylococcus epidermidis is the leading cause of nosocomial and biofilm-associated infections. Little is known about the mechanisms by which S. epidermidis protects itself against the innate human immune system during colonization and infection. We used scanning electron microscopy to demonstrate that the exopolysaccharide intercellular adhesin (PIA) resides in fibrous strands on the bacterial cell surface, and that lack of PIA production results in complete loss of the extracellular matrix material that has been suggested to mediate immune evasion. Phagocytosis and killing by human polymorphonuclear leucocytes was significantly increased in a mutant strain lacking PIA production compared with the wild-type strain. The mutant strain was also significantly more susceptible to killing by major antibacterial peptides of human skin, cationic human beta-defensin 3 and LL-37, and anionic dermcidin. PIA represents the first defined factor of the staphylococcal biofilm matrix that protects against major components of human innate host defence.     

Proteomics approach to identifying ATP-covalently modified proteins

This study aims to investigate functionally similar proteins based on their capacity to remain bound to ATP under stringent resolving conditions. Using two-dimensional gel electrophoresis and capillary liquid chromatography on-line mass spectrometry, we have identified several mammalian and E. coli proteins that appear to covalently bind ATP. To validate this approach, we obtained commercially purified forms of proteins identified from two-dimensional protein maps and tested their capacity to bind alpha 32P phosphate labeled ATP. This proteomics approach provides an initial screening method of identifying functionally similar proteins for further scrutiny by a more traditional analysis.     

Dynamic changes in nitric oxide and mitochondrial oxidative stress with site-dependent differential tissue response during anoxic preconditioning in rat heart

In this study, dynamic changes in nitric oxide (NO) and mitochondrial superoxide (O(2)(*-)) were examined during anoxic preconditioning (AP) in rat heart model. AP and anoxia-reoxygenation (A/R) were performed on isolated hearts and single cardiomyocytes. The cellular insult in the form of infarct size and DNA damage were localized and correlated with NO synthases (endothelial and inducible) expression levels. The results showed that endocardium was the most affected region in AP groups, whereas the larger area of infarct was confined to mid- and epicardium in the A/R group. Interestingly, a high-level expression of immunofluorescent NO synthases was restricted to viable areas in the AP. In contrast to the gradual increase in O(2)(*-) level that occurred in the AP group, a sudden massive increase in its level was demonstrated at the onset of reoxygenation in the A/R group. The observed increase in NO production during reoxygenation in the AP group was attenuated by inducible NO synthase inhibitor. The study revealed, on a real-time basis, the role played by preconditioning for modulating NO and O(2)(*-) levels on behalf of cell survival. The results afford a better understanding of cardiac-adapting mechanism during AP and the role of inducible NO synthase in this important phenomenon.     

Selenoproteins of the thyroid gland: expression, localization and possible function of glutathione peroxidase 3

The thyroid gland has an exceptionally high selenium content, even during selenium deficiency. At least 11 selenoproteins are expressed, which may be involved in the protection of the gland against the high amounts of H2O2 produced during thyroid hormone biosynthesis. As determined here by in situ hybridization and Northern blotting experiments, glutathione peroxidases (GPx) 1 and 4 and selenoprotein P were moderately expressed, occurring selectively in the follicular cells and in leukocytes of germinal follicles of thyroids affected by Hashimoto's thyroiditis. Selenoprotein 15 was only marginally expressed and distributed over all cell types. GPx3 mRNA was exclusively localized to the thyrocytes, showed the highest expression levels and was down-regulated in 5 of 6 thyroid cancer samples as compared to matched normal controls. GPx3 could be extracted from thyroidal colloid by incubation with 0.5% sodium dodecyl sulfate indicating that this enzyme is (i) secreted into the follicular lumen and (ii) loosely attached to the colloidal thyroglobulin. These findings are consistent with a role of selenoproteins in the protection of the thyroid from possible damage by H2O2. Particularly, GPx3 might use excess H2O2 and catalyze the polymerization of thyroglobulin to the highly cross-linked storage form present in the colloid.     

Quantifying the emergence of dengue in Hanoi, Vietnam: 1998-2009

Background

An estimated 2.4 billion people live in areas at risk of dengue transmission, therefore the factors determining the establishment of endemic dengue in areas where transmission suitability is marginal is of considerable importance. Hanoi, Vietnam is such an area, and following a large dengue outbreak in 2009, we set out to determine if dengue is emerging in Hanoi.

Methods and Principal Findings

We undertook a temporal and spatial analysis of 25,983 dengue cases notified in Hanoi between 1998 and 2009. Age standardized incidence rates, standardized age of infection, and Standardized Morbidity Ratios (SMR) were calculated. A quasi-Poisson regression model was used to determine if dengue incidence was increasing over time. Wavelet analysis was used to explore the periodicity of dengue transmission and the association with climate variables. After excluding the two major outbreak years of 1998 and 2009 and correcting for changes in population age structure, we identified a significant annual increase in the incidence of dengue cases over the period 1999–2008 (incidence rate ratio  = 1.38, 95% confidence interval  = 1.20–1.58, p value  = 0.002). The age of notified dengue cases in Hanoi is high, with a median age of 23 years (mean 26.3 years). After adjusting for changes in population age structure, there was no statistically significant change in the median or mean age of dengue cases over the period studied. Districts in the central, highly urban, area of Hanoi have the highest incidence of dengue (SMR>3).

Conclusions

Hanoi is a low dengue transmission setting where dengue incidence has been increasing year on year since 1999. This trend needs to be confirmed with serological surveys, followed by studies to determine the underlying drivers of this emergence. Such studies can provide insights into the biological, demographic, and environmental changes associated with vulnerability to the establishment of endemic dengue.     

Two new flavones from Eupatorium coelestinum

Besides coumarin, nobiletin, lucidin dimethyl ether and 5,6,7,3′,4′-pentamethoxyflavone, two new highly oxygenated flavones were isolated from Eupatorium coelestinum. Their structures were determined by spectroscopic methods and alkaline degradations as 5,6,7,8,3′,4′,5′ -heptamethoxyflavone and 5,6,7,8,5′-pentamethoxy-3′,4′-methylenedioxyflavone.