Improving salinity tolerance in the most widely cultivated cereal, bread wheat (Triticum aestivum L.), is essential to increase grain yields on saline agricultural lands. A Portuguese landrace, Mocho de Espiga Branca accumulates up to sixfold greater leaf and sheath sodium (Na+) than two Australian cultivars, Gladius and Scout, under salt stress in hydroponics. Despite high leaf and sheath Na+ concentrations, Mocho de Espiga Branca maintained similar salinity tolerance compared to Gladius and Scout. A naturally occurring single nucleotide substitution was identified in the gene encoding a major Na+ transporter TaHKT1;5-D in Mocho de Espiga Branca, which resulted in a L190P amino acid residue variation. This variant prevents Mocho de Espiga Branca from retrieving Na+ from the root xylem leading to a high shoot Na+ concentration. The identification of the tissue-tolerant Mocho de Espiga Branca will accelerate the development of more elite salt-tolerant bread wheat cultivars. 相似文献
Iron (Fe) is essential for phytoplankton growth and photosynthesis, and is proposed to be an important factor regulating algal blooms under replete major nutrients in coastal environments. Here, Skeletonema costatum, a typical red-tide diatom species, and Chlorella vulgaris, a widely distributed Chlorella, were chosen to examine carbon fixation and Fe uptake by coastal algae under dark and light conditions with different Fe levels. The cellular carbon fixation and intracellular Fe uptake were measured via 14C and 55Fe tracer assay, respectively. Cell growth, cell size, and chlorophyll-α concentration were measured to investigate the algal physiological variation in different treatments. Our results showed that cellular Fe uptake proceeds under dark and the uptake rates were comparable to or even higher than those in the light for both algal species. Fe requirements per unit carbon fixation were also higher in the dark resulting in higher Fe: C ratios. During the experimental period, high Fe addition significantly enhanced cellular carbon fixation and Fe uptake. Compared to C. vulgaris, S. costatum was the common dominant bloom species because of its lower Fe demand but higher Fe uptake rate. This study provides some of the first measurements of Fe quotas in coastal phytoplankton cells, and implies that light and Fe concentrations may influence the phytoplankton community succession when blooms occur in coastal ecosystems. 相似文献
HIV preferentially infects activated CD4+ T cells. Current antiretroviral therapy cannot eradicate the virus. Viral infection of other cells such as macrophages may contribute to viral persistence during antiretroviral therapy. In addition to cell-free virus infection, macrophages can also get infected when engulfing infected CD4+ T cells as innate immune sentinels. How macrophages affect the dynamics of HIV infection remains unclear. In this paper, we develop an HIV model that includes the infection of CD4+ T cells and macrophages via cell-free virus infection and cell-to-cell viral transmission. We derive the basic reproduction number and obtain the local and global stability of the steady states. Sensitivity and viral dynamics simulations show that even when the infection of CD4+ T cells is completely blocked by therapy, virus can still persist and the steady-state viral load is not sensitive to the change of treatment efficacy. Analysis of the relative contributions to viral replication shows that cell-free virus infection leads to the majority of macrophage infection. Viral transmission from infected CD4+ T cells to macrophages during engulfment accounts for a small fraction of the macrophage infection and has a negligible effect on the total viral production. These results suggest that macrophage infection can be a source contributing to HIV persistence during suppressive therapy. Improving drug efficacies in heterogeneous target cells is crucial for achieving HIV eradication in infected individuals.
AbstractThe emergent need for new treatment methods for multi-drug resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) has focused attention on novel potential tools like nanoparticles (NPs). In the present study, a drug-free cationic nanoparticles (CNPs) system was developed and its anti-MRSA effects were firstly investigated. The results showed that CNPs (261.7?nm, 26.1?mv) showed time- and concentration-dependent activity against MRSA growth, killing ~ 90% of planktonic bacterial cells in 3?h at 400?μg ml?1, and completely inhibiting biofilm formation at 1000?μg ml?1. Moreover, CNPs at 400?μg ml?1 reduced the minimum inhibitory concentration (MIC) of vancomycin on inhibition of planktonic MRSA growth (~ 25%) and biofilm formation (~ 50%). The CNPs–bacteria interaction force was up to 22 nN. Overall, these data suggest that CNPs have a good potential in clinical applications for the prevention and treatment of MRSA infection. 相似文献
Beyond their widespread application as genome-editing and regulatory tools, clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems also play a critical role in nucleic acid detection due to their high sensitivity and specificity. Recently developed Cas family effectors have opened the door to the development of new strategies for detecting different types of nucleic acids for a variety of purposes. Precise and efficient nucleic acid detection using CRISPR-Cas systems has the potential to advance both basic and applied biological research. In this review, we summarize the CRISPR-Cas systems used for the recognition and detection of specific nucleic acids for different purposes, including the detection of genomic DNA, nongenomic DNA, RNA, and pathogenic microbe genomes. Current challenges and further applications of CRISPR-based detection methods will be discussed according to the most recent developments. 相似文献
Workers who are exposed to extreme heat or work in hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational illnesses and injuries. On the other hand, local and regional heat therapy has been used for the treatment of some cancers, such as liver cancer, lung cancer, and kidney cancer. Although heat stress has been shown to induce the accumulation of p53 protein, a key regulator of cell cycle, apoptosis, DNA repair, and autophagy, how it regulates p53 protein accumulation and what the p53 targets are remain unclear. Here, we show that, among various genotoxic stresses, including ionizing radiation (IR) and ultraviolet (UV) radiation, heat stress contributes significantly to increase p53 protein levels in normal liver cells and liver cancer cells. Heat stress did not increase p53 mRNA expression as well as p53 promoter activity. However, heat stress enhanced the half-life of p53 protein. Moreover, heat stress increased the expression of puma and light chain 3 (LC-3), which are associated with the apoptotic and autophagic function of p53, respectively, whereas it did not change the expression of the cell cycle regulators p21, 14-3-3δ, and GADD45α, suggesting that heat-triggered alteration of p53 selectively modulates the downstream targets of p53. Our study provides a novel mechanism by which heat shock stimulates p53 protein accumulation, which is different from common DNA damages, such as IR and UV, and also provides new molecular basis for heat injuries or heat therapy. 相似文献
Studies focusing on the association of gene methylthioadenosine phosphorylase (MTAP) with the risk of coronary artery disease (CAD) and myocardial infarction (MI) are limited. 相似文献
Genetic polymorphisms of glutathione S-transferases (GSTs) and type 2 diabetes mellitus (T2DM) risk have been widely studied, however, the results were somewhat conflicting. To evaluate the association of GSTs (GSTM1, GSTT1 and GSTP1) gene polymorphisms with T2DM, a meta-analysis was performed before October, 2012. ORs were pooled according to random-effects model. There were a total of 1354/1666 (n = 9) cases/controls (studies) for GSTM1, 1271/1470 (n = 8) for GSTT1, and 1205/1250 (n = 7) for GSTM1. There were significant associations between GSTM1 polymorphism, GSTT1 polymorphism and T2DM in the contrast of present genotype vs. null genotype, with pooled OR = 1.99 (95%CI = 1.46–2.71) and OR = 1.61 (95%CI = 1.19–2.17), respectively. Yet no significant association of GSTP1 polymorphism and T2DM was showed. When stratified by ethnicity, the significant associations were also existed in Asians for GSTM1 and GSTT1, but not GSTP1. No publication bias but some extent of heterogeneity was observed. Finally, the accumulated evidence proved the obvious associations of GSTM1 and GSTT1 polymorphisms with an increased risk of T2DM. 相似文献