Hexa-Acylated Lipid A Is Required for Host Inflammatory Response to Neisseria gonorrhoeae in Experimental Gonorrhea

ABSTRACT Neisseria gonorrhoeae causes gonorrhea, a sexually transmitted infection characterized by inflammation of the cervix or urethra. However, a significant subset of patients with N. gonorrhoeae remain asymptomatic, without evidence of localized inflammation. Inflammatory responses to N. gonorrhoeae are generated by host innate immune recognition of N. gonorrhoeae by several innate immune signaling pathways, including lipooligosaccharide (LOS) and other pathogen-derived molecules through activation of innate immune signaling systems, including toll-like receptor 4 (TLR4) and the interleukin-1β (IL-1β) processing complex known as the inflammasome. The lipooligosaccharide of N. gonorrhoeae has a hexa-acylated lipid A. N. gonorrhoeae strains that carry an inactivated msbB (also known as lpxL1 ) gene produce a penta-acylated lipid A and exhibit reduced biofilm formation, survival in epithelial cells, and induction of epithelial cell inflammatory signaling. We now show that msbB -deficient N. gonorrhoeae induces less inflammatory signaling in human monocytic cell lines and murine macrophages than the parent organism. The penta-acylated LOS exhibits reduced toll-like receptor 4 signaling but does not affect N. gonorrhoeae -mediated activation of the inflammasome. We demonstrate that N. gonorrhoeae msbB is dispensable for initiating and maintaining infection in a murine model of gonorrhea. Interestingly, infection with msbB -deficient N. gonorrhoeae is associated with less localized inflammation. Combined, these data suggest that TLR4-mediated recognition of N. gonorrhoeae LOS plays an important role in the pathogenesis of symptomatic gonorrhea infection and that alterations in lipid A biosynthesis may play a role in determining symptomatic and asymptomatic infections

Microbial nitrogen limitation in the mammalian large intestine

Resource limitation is a fundamental factor governing the composition and function of ecological communities. However, the role of resource supply in structuring the intestinal microbiome has not been established and represents a challenge for mammals that rely on microbial symbionts for digestion: too little supply might starve the microbiome while too much might starve the host. We present evidence that microbiota occupy a habitat that is limited in total nitrogen supply within the large intestines of 30 mammal species. Lowering dietary protein levels in mice reduced their faecal concentrations of bacteria. A gradient of stoichiometry along the length of the gut was consistent with the hypothesis that intestinal nitrogen limitation results from host absorption of dietary nutrients. Nitrogen availability is also likely to be shaped by host-microbe interactions: levels of host-secreted nitrogen were altered in germ-free mice and when bacterial loads were reduced via experimental antibiotic treatment. Single-cell spectrometry revealed that members of the phylum Bacteroidetes consumed nitrogen in the large intestine more readily than other commensal taxa did. Our findings support a model where nitrogen limitation arises from preferential host use of dietary nutrients. We speculate that this resource limitation could enable hosts to regulate microbial communities in the large intestine. Commensal microbiota may have adapted to nitrogen-limited settings, suggesting one reason why excess dietary protein has been associated with degraded gut-microbial ecosystems

Transformation of Soybeans with GFP and GUS Genes Aided by Vir Proteins of Agrobacterium

Agrobacterium mediated transformation is widely used in plant genetic engineering. However, most economically important crops are not amenable to the method. Physical methods such as direct DNA uptake, microinjection, electroporation and microprojectile bombardment are used in these plants. However, these alternative methods are not as efficient. We used a combination of physical and Agrobacterium methods in our project. First, the total vir proteins were isolated from Agrobacterium, then mixed with transgenic DNA. The mixture was loaded on tungsten microcarrier and shot into soybean cotyledon nodes. We also used vir proteins in transient expression assay. Our experiments show that vir proteins decreased the transient expression of green fluorescent protein (GFP) in both protoplasts DNA uptake and gene gun methods, however they may enhance stable incorporation of the GUS gene

Recent Surge Behavior of Walsh Glacier Revealed by Remote Sensing Data

Many surge-type glaciers are present on the St. Elias Mountains, but a detailed study on the surge behavior of the glaciers is still missing. In this study, we used remote sensing data to reveal detailed glacier surge behavior, focusing on the recent surge at Walsh Glacier, which was reported to have surged once in the 1960s. Glacial velocities were derived using a cross-correlation algorithm, and changes in the medial moraines were interpreted based on Landsat images. The digital elevation model (DEM) difference method was applied to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEMs to evaluate the surface elevation of the glacier. The results showed that the surge initiated near the conjunction of the eastern and northern branches, and then quickly spread downward. The surge period was almost three years, with an active phase of less than two years. The advancing speed of the surge front was much large than the maximum ice velocity of ≈14 m/d observed during the active phase. Summer speed-ups and a winter speed-up in ice velocity were observed from velocity data, with the speed-ups being more obvious during the active phase. Changes in the glacier velocity and the medial moraines suggested that the eastern branch was more affected by the surge. The DEM differencing results showed that the receiving zone thickened up to about 140 m, and the upstream reservoir zone became thinner. These surge behaviors, as characterized by remote sensing data, gave us more detailed insights into the surge dynamics of Walsh Glacier

Nano-carriers and their drug release

One of the hottest fields in biomedicine research is to encapsulate drugs and release them in particular organs by using nano-platform.Because nanoparticles can enter most cancer cells easily and accumulate inside the cells,drug-loaded nanoparticles with targeting modification can help to increase the drug concentration in lesion position,enhancing the drug effects and reducing the toxicity.In general,drug-loaded nanoparticles release drugs by diffusion or erosion.There are many ways to stimulate the release of drugs from nanoparticles,including pH,enzyme,light,magnetism,and ultrasound responses.This article reviews the principle and recent advances of drug-loaded nanoparticles