红腹锦鸡和白腹锦鸡卵壳的超微结构

本文报道了锦鸡属——白腹锦鸡和红腹锦鸡卵壳的气孔、外壳膜、锥体层、木栅层的超微结构。并对两者的卵壳进行了比较。     

Nitric Oxide Enhances Salt Tolerance in Tomato Seedlings by Regulating Endogenous S-nitrosylation Levels

Salinity impairs plant growth and development, thereby leading to low yield and inferior quality of crops. Nitric oxide (NO) has emerged as an essential signaling molecule that is involved in regulating various physiological and biochemical processes in plants. In this study, tomato seedlings of Lycopersicum esculentum L. “Micro-Tom” treated with 150 mM sodium chloride (NaCl) conducted decreased plant height, total root length, and leaf area by 25.43%, 24.87%, and 33.67%, respectively. While nitrosoglutathione (GSNO) pretreatment ameliorated salt toxicity in a dose-dependent manner and 10 µM GSNO exhibited the most significant mitigation effect. It increased the plant height, total root length, and leaf area of tomato seedlings, which was 31.44%, 20.56%, and 51.21% higher than NaCl treatment alone, respectively. However, NO scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide potassium (cPTIO) treatment reversed the positive effect of NO under salt stress, implying that NO is essential for the enhancement of salt tolerance. Additionally, NaCl?+?GSNO treatment effectively decreased O^2? production and H₂O₂ content, increased the levels of soluble sugar, glycinebetaine, proline, and chlorophyll, and enhanced the activities of antioxidant enzymes and the content of antioxidants in tomato seedlings in comparison with NaCl treatment, whereas NaCl?+?cPTIO treatment significantly reversed the effect of NO under salt stress. Moreover, we found that GSNO treatment increased endogenous NO content, S-nitrosoglutathione reductase (GSNOR) activity, GSNOR expression and total S-nitrosylated level, and decreased S-nitrosothiol (SNO) content under salt stress, implicating that S-nitrosylation might be involved in NO-enhanced salt tolerance in tomatoes. Altogether, these results suggest that NO confers salt tolerance in tomato seedlings probably by the promotion of photosynthesis and osmotic balance, the enhancement of antioxidant capability and the increase of protein S-nitrosylation levels.

     

The Puccinia striiformis effector Hasp98 facilitates pathogenicity by blocking the kinase activity of wheat TaMAPK4

The obligate biotrophic fungus Puccinia striiformis f. sp. tritici (Pst) employs virulence effectors to disturb host immunity and causes devastating stripe rust disease. However, our understanding of how Pst effectors regulate host defense responses remains limited. In this study, we determined that the Pst effector Hasp98, which is highly expressed in Pst haustoria, inhibits plant immune responses triggered by flg22 or nonpathogenic bacteria. Overexpression of Hasp98 in wheat (Triticum aestivum) suppressed avirulent Pst-triggered immunity, leading to decreased H₂O₂ accumulation and promoting P. striiformis infection, whereas stable silencing of Hasp98 impaired P. striiformis pathogenicity. Hasp98 interacts with the wheat mitogen-activated protein kinase TaMAPK4, a positive regulator of plant resistance to stripe rust. The conserved TEY motif of TaMAPK4 is important for its kinase activity, which is required for the resistance function. We demonstrate that Hasp98 inhibits the kinase activity of TaMAPK4 and that the stable silencing of TaMAPK4 compromises wheat resistance against P. striiformis. These results suggest that Hasp98 acts as a virulence effector to interfere with the MAPK signaling pathway in wheat, thereby promoting P. striiformis infection.     

1-D Metal-Dielectric-Metal Grating Structure as an Ultra-Narrowband Perfect Plasmonic Absorber in the Visible and Its Application in Glucose Detection

The need for an easy to fabricate perfect and narrowband light absorber in the visible range of electromagnetic (EM) spectrum has always been in demand for many scientific and device applications. Here, we propose a metal-dielectric-metal (MDM) 1-D grating plasmonic structure as a perfect narrow band light absorber in the visible and its application in glucose detection. The proposed structure consists of a 1- D grating of gold on the top of a dielectric layer on a gold film. Optimization for dielectric grating index (n), grating thickness (t), grating width (W), and grating period (P) has been done to improve the performance of plasmonic structure by calculating its quality factor and figure-of-merit (FOM). The optimized plasmonic structure behaves as a perfect narrowband light absorber. The flexibility to work at a specific wavelength is also offered by the proposed structure through an appropriate selection of the geometrical parameters and refractive index of the dielectric grating. The equivalent RC model is used to understand different components of the proposed structure on the optical response. The absorption response of the structure is invariant to the incident angle. Moreover, the calculated absorbance of the proposed plasmonic structure is ~ 100% with a narrow full-width half maxima (FWHM) of ~ 2.8 nm. We have numerically demonstrated a potential application of the proposed MDM absorber as a plasmonic glucose sensor in the visible range with detection sensitivity in the range of 140 to 195 nm/RIU.

     

VRAA: virtualized resource auction and allocation based on incentive and penalty

Virtualization is widely used in cloud computing environments to efficiently manage resources, but it also raises several challenges. One of them is the fairness issue of resource allocation among virtual machines. Traditional virtualized resource allocation approaches distribute physical resources equally without taking into account the actual workload of each virtual machine and thus often leads to wasting. In this paper, we propose a virtualized resource auction and allocation model (VRAA) based on incentive and penalty to correct this wasting problem. In our approach, we use Nash equilibrium of cooperative games to fairly allocate resources among multiple virtual machines to maximize revenue of the system. To illustrate the effectiveness of the proposed approach, we then apply the basic laws of auction gaming to investigate how CPU allocation and contention can affect applications’ performance (i.e., response time), and its effect on CPU utilization. We find that in our VRAA model, the fairness index is high, and the resource allocation is closely proportional to the actual workloads of the virtual machines, so the wasting of resources is reduced. Experiment results show that our model is general, and can be applied to other virtualized non-CPU resources.     

Modified McKeown Minimally Invasive Esophagectomy for Esophageal Cancer: A 5-Year Retrospective Study of 142 Patients in a Single Institution

Background

To achieve decreased invasiveness and lower morbidity, minimally invasive esophagectomy (MIE) was introduced in 1997 for localized esophageal cancer. The combined thoracoscopic-laparoscopic esophagectomy (left neck anastomosis, defined as the McKeown MIE procedure) has been performed since 2007 at our institution. From 2007 to 2011, our institution subsequently evolved as a high-volume MIE center in China. We aim to share our experience with MIE, and have evaluated the outcomes of 142 patients.

Methods

We retrospectively reviewed 142 consecutive patients who had presented with esophageal cancer undergoing McKeown MIE from July 2007 to December 2011. The procedure, surgical outcomes, disease-free and overall survival of these cases were assessed.

Results

The average total procedure time was 270.5±28.1 min. The median operation time for thoracoscopy was 81.5±14.6 min and for laparoscopy was 63.8±9.1 min. The average blood loss associated with thoracoscopy was 123.8±39.2 ml, and for laparoscopic procedures was 49.9±14.3 ml. The median number of lymph nodes retrieved was 22.8. The 30 day mortality rate was 0.7%. Major surgical complications occurred in 24.6% and major non-surgical complications occurred in 18.3% of these patients. The median DFS and OS were 36.0±2.6 months and 43.0±3.4 months respectively.

Conclusions

Surgical and oncological outcomes following McKeown MIE for esophageal cancer were acceptable and comparable with those of open-McKeown esophagectomy. The procedure was both feasible and safe – properties that can be consolidated by experience.     

Serum Uric Acid and Non-Alcoholic Fatty Liver Disease in Non-Diabetic Chinese Men

Increased serum uric acid (SUA) levels may be involved in the development of non-alcoholic fatty liver disease (NAFLD) in men presenting with metabolic syndrome (MetS) and/or insulin resistance. We aimed to determine the independent relationship between SUA and NAFLD in non-diabetic Chinese male population, and to explore the determinants of SUA levels among indexes of adiposity, lipid, and genotypes pertaining to triglycerides metabolism, inflammation, oxidative stress, and SUA concentrations. A total of 1440 men, classified depending on the presence of ultrasonographically detected NAFLD, underwent a complete healthy checkup program. Genotypes were extracted from our previously established genome-wide association study database. After adjusting for age, smoking, drinking, body mass index, homeostasis model assessment of insulin resistance, C-reactive protein, creatinine, alanine aminotransferase (ALT) and components of metabolic syndrome, the odds ratio for NAFLD, comparing the highest with the lowest SUA quartile, was 2.81 (95% confidence interval 1.66–4.76). A stepwise multivariate linear regression analysis (R² = 0.238, P<0.001) retained age, waist circumference, serum creatinine, triglycerides, the Q141K variant in ABCG2 (rs2231142) and NAFLD as significant predictors of SUA levels (all P<0.001). Besides, ALT and Met196Arg variant in TNFRSF1B (rs1061622) additionally associated with SUA among individuls with NAFLD. Our data suggest that in Chinese men, elevated SUA is significantly associated with NAFLD, independent of insulin resistance and other metabolic disorders, such as central obesity or hypertriglyceridemia. Meanwhile, among subjects with NAFLD, index of liver damage, such as elevated ALT combined with genetic susceptibility to inflammation associated with increased SUA levels.     

Application of exogenous substances reduces tobacco-specific nitrosamines content by regulating biosynthesis of nicotine and nitrite in burley tobacco

Tobacco-specific nitrosamines (TSNAs) are carcinogenic chemicals found in tobacco plants. The increasing health consciousness of individuals had led to an increased interest in research on reducing TSNAs content. The aim of this study was to use a pot experiment in which exogenous substances were applied to burley tobacco to dissect the mechanism of TSNAs production. The results indicated that spraying the exogenous substances IAA, NAA, SA and combination thereof on burley tobacco after topping decreased TSNAs content by 2.69–29.4 % in upper leaves and 0.23–39.3 % in middle leaves without affecting total sugar, total nitrogen, potassium and chlorine contents. The application of exogenous substances could down-regulate expression of the NR gene and the activity of the NR enzyme, resulting in less accumulation of the TSNAs precursor nitrite. The exogenous substances significantly reduced nicotine accumulation, which was consistent with low enzyme activities and the down-regulated expressions of genes involved in nicotine biosynthesis, especially significant in the case of quinolinate phosphoribosyltransferase. These results suggested that the application of exogenous substances on burley tobacco after topping could reduce TSNAs content which may be attributed to the regulation of exogenous substances on nitrite and nicotine. This also implies one potential improvement to agronomic practices aimed at controlling the accumulation of TSNAs in burley tobacco.     

Characterization and comparative analysis of a second thermonuclease from Staphylococcus aureus

Staphylococcal nuclease (here termed as Nuc1) is considered an important virulence factor and a unique marker widely used in the detection of Staphylococcus aureus. A second functional thermostable nuclease (here termed as Nuc2) in S. aureus was characterized after recombinant expression in Escherichia coli. Sequence alignment and phylogenetic analysis revealed that Nuc2 was a more conserved protein in the staphylococci group compared with Nuc1. Recombinant Nuc2 showed nuclease activity in the zymogram test and was able to degrade various types of nucleic acids. The optimal reaction temperature and pH for Nuc2 were 50 °C and pH 10, respectively. The enzymatic activity of Nuc2 was stimulated in the presence of Ca²⁺ (0.05 mM), Mg²⁺ (0.5 mM), dithiothreitol, β-mecaptoethanol, TritonX-100, Tween-20, and urea; however, activity decreased sharply when exposed to heavy metals such as Zn²⁺ and Mn²⁺, and in the presence of EDTA or SDS. Nuc2 showed weaker activity, lower thermostability and different sensitivity to these chemical agents compared with Nuc1, which was consistent with differences in the sequence pattern and structure predicted. Furthermore, a nuc1 and nuc2 double deletion mutant of S. aureus and respective complementation experiments suggest a major role for nuc1 in terms of thermonuclease activity in S. aureus.