Rapid detection of viable salmonellae in produce by coupling propidium monoazide with loop-mediated isothermal amplification

Recent outbreaks linked to Salmonella-contaminated produce heightened the need to develop simple, rapid, and accurate detection methods, particularly those capable of determining cell viability. In this study, we examined a novel strategy for the rapid detection and quantification of viable salmonellae in produce by coupling a simple propidium monoazide sample treatment with loop-mediated isothermal amplification (PMA-LAMP). We first designed and optimized a LAMP assay targeting Salmonella. Second, the performance of PMA-LAMP for detecting and quantifying viable salmonellae was determined. Finally, the assay was evaluated in experimentally contaminated produce items (cantaloupe, spinach, and tomato). Under the optimized condition, PMA-LAMP consistently gave negative results for heat-killed Salmonella cells with concentrations up to 10(8) CFU/ml (or CFU/g in produce). The detection limits of PMA-LAMP were 3.4 to 34 viable Salmonella cells in pure culture and 6.1 × 10(3) to 6.1 × 10(4) CFU/g in spiked produce samples. In comparison, PMA-PCR was up to 100-fold less sensitive. The correlation between LAMP time threshold (T(T)) values and viable Salmonella cell numbers was high (R(2) = 0.949 to 0.993), with a quantification range (10(2) to 10(5) CFU/reaction in pure culture and 10(4) to 10(7) CFU/g in produce) comparable to that of PMA in combination with quantitative real-time PCR (PMA-qPCR). The complete PMA-LAMP assay took about 3 h to complete when testing produce samples. In conclusion, this rapid, accurate, and simple method to detect and quantify viable Salmonella cells in produce may present a useful tool for the produce industry to better control potential microbial hazards in produce.     

Involvement of auxin and nitric oxide in plant Cd-stress responses

Cadmium (Cd) toxicity inhibited the seedling growth while inducing the occurrences of lateral roots (LR) and adventitious roots (AR). Further study indicated that auxin and nitric oxide (NO) are involved in the processes. In this study, we chose model plant Arabidopsis thaliana and Cd-hyperaccumulator Solanum nigrum as material to examine the involvement of Cd-induced auxin redistribution in NO accumulation in plants and the effect of NO on Cd accumulation. For this aim, the histochemical staining, NO fluorescence probe (DAF-2DA) detections combined with the pharmacological study were used in this study. By using DR5:GUS staining analysis combined with NO fluorescence probe (DAF-2DA) detection, we found that Cd-induced NO accumulation is at least partly due to auxin redistribution in plants exposure to Cd. Supplementation with SNP donor S-nitrosoglutathione (GSNO) increased the number of LR and AR. In contrast, NO-scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl imidazoline-1-oxyl-3-oxide (cPTIO) reversed the effects of NO on modulating root system architecture and Cd accumulation. These results suggest that manipulation of the NO level is an effective approach to improve Cd tolerance in plants by modulating the development of LR and AR, and provide insights into novel strategies for phytoremediation.     

海南霸王岭天然次生林边缘效应下木质藤本与树木的关系

选择海南岛霸王岭天然恢复60 a的次生林样地中形成年限为17和13年的边缘,分别设置4条10 m100 m的样带,研究边缘效应下dbh ≥1 cm树木的攀藤率、被藤本攀附的频度和每木藤本数随距边缘距离的变化。结果表明：在0.8 hm2的样带中,树木的攀藤率分别为44.58%（17年边缘）和32.63%（13年边缘）。2种边缘中,dbh 1—5 cm、5—10 cm树木的攀藤率都随距离发生了变化,17年边缘中dbh ＞20 cm和13年边缘中dbh 10—20 cm树木的攀藤率都没有随距离的变化而变化。树木被藤本攀附的频度随距边缘距离的增加而降低,攀附3株以上藤本的树木最少,在17年边缘中变化趋势较明显;攀附1株藤本的树木最多,在13年边缘中变化明显。17年边缘中每木藤本数随距离增加而降低。在边缘形成初期,边缘形成年限对每木藤本数产生了影响,其在17年边缘中下降程度较大,但总体高于13年边缘中。     

Macrophage colony-stimulating factor and its receptor signaling augment glycated albumin-induced retinal microglial inflammation in vitro

Background  

Microglial activation and the proinflammatory response are controlled by a complex regulatory network. Among the various candidates, macrophage colony-stimulating factor (M-CSF) is considered an important cytokine. The up-regulation of M-CSF and its receptor CSF-1R has been reported in brain disease, as well as in diabetic complications; however, the mechanism is unclear. An elevated level of glycated albumin (GA) is a characteristic of diabetes; thus, it may be involved in monocyte/macrophage-associated diabetic complications.     

Waist-to-height ratio is an accurate and easier index for evaluating obesity in children and adolescents

Objectives: The present study aims to evaluate the accuracy of the index of waist‐to‐height ratio (WHTR), and proposed the optimal thresholds of WHTR in the definition of childhood overweight and obesity in a bi‐ethnic Chinese school‐aged population. Research Methods and Procedures: Overweight and obese were identified by BMI for age and gender in a random sample including 2055 Han and 2132 Uygur ethnic school‐aged children (8 to 18 years old). WHTR was calculated by waist circumference divided by height on the basis of standard anthropometric measurements. Receiver operating characteristic (ROC) curve analyses were performed to assess the accuracy of WHTR as a diagnostic test for childhood overweight and obesity, compared with waist circumference. The optimal thresholds of WHTR for defining overweight and obesity were recommended respectively by gender. The correlation between WHTR and age was analyzed and compared with BMI. Results: A‐values (area under curve) of WHTR for diagnosing overweight and obesity were both over 0.90 in both genders and better than those of waist circumference. A threshold of 0.445 was identified for overweight in both genders, with the sensitivity and specificity >0.80. The thresholds for defining obesity was 0.485 in boys and 0.475 in girls, both having the sensitivity and specificity >0.90. WHTR showed less association with age than BMI. Conclusions: WHTR is a simple, easy, accurate, and non‐age‐dependent index with high applicability to screening overweight and obesity in children and adolescents. The use of WHTR in the general childhood population has been justified by this study.     

Bacterial Phosphoproteomic Analysis Reveals the Correlation Between Protein Phosphorylation and Bacterial Pathogenicity

Increasing evidence shows that protein phosphorylation on serine, threonine and tyrosine residues is a major regulatory post-translational modification in the bacteria. This review focuses on the implications of bacterial phosphoproteome in bacterial pathogenicity and highlights recent development of methods in phosphoproteomics and the connectivity of the phosphorylation networks. Recent technical developments in the high accuracy mass spectrometry have dramatically transformed proteomics and made it possible the characterization of a few exhaus- tive site-specific bacterial phosphoproteomes. The high abundance of tyrosine phosphorylations in a few bacterial phosphoproteomes suggests their roles in the pathogenicity, especially in the case of pathogen-host interactions; the high abundance of multi-phosphorylation sites in bacterial phosphoprotein is a compensation of the relatively small phosphorylation size and an indicator of the delicate regulation of protein functions.     

Role of two-component regulatory systems in intracellular survival of Mycobacterium tuberculosis

The typical two-component regulatory systems (TCSs), consisting of response regulator and histidine kinase, play a central role in survival of pathogenic bacteria under stress conditions such as nutrient starvation, hypoxia, and nitrosative stress. A total of 11 complete paired two-component regulatory systems have been found in Mycobacterium tuberculosis, including a few isolated kinase and regulatory genes. Increasing evidence has shown that TCSs are closely associated with multiple physiological process like intracellular persistence, pathogenicity, and metabolism. This review gives the two-component signal transduction systems in M. tuberculosis and their signal transduction roles in adaption to the environment.     

ent-Pimarane Diterpenes from the Aerial Parts of Siegesbeckia pubescens

Five new ent-pimarane diterpenes ( 1 – 5 ) and five known analogs ( 6 – 10 ) were isolated from the aerial parts of Siegesbeckia pubescens. Their structures, including absolute configurations, were determined by comprehensive spectroscopic methods especially 1D and 2D NMR and quantum chemical electronic circular dichroism calculations. All the isolated compounds were evaluated for their cytotoxicity against human BT549, A549 and H157 cancer cell lines. Among them, compounds 1 and 2 showed mild cytotoxicity against lung cancer cell lines H157 with IC₅₀ values of 16.35±2.59 and 18.86±4.83 μM, respectively.