papers

Production of an extracellular matrix is essential for biofilm formation, as this matrix both secures and protects the cells it encases. Mechanisms underlying production and assembly of matrices are poorly understood. Vibrio cholerae, relies heavily on biofilm formation for survival, infectivity, and transmission. Biofilm formation requires Vibrio polysaccharide (VPS), which is produced by vps gene-products, yet the function of these products remains unknown. Here, we demonstrate that the vps gene-products vpsO and vpsU encode respectively for a tyrosine kinase and a cognate tyrosine phosphatase. Collectively, VpsO and VpsU act as a tyrosine phosphoregulatory system to modulate VPS production. We present structures of VpsU and the kinase domain of VpsO, and we report observed autocatalytic tyrosine phosphorylation of the VpsO C-terminal tail. The position and amount of tyrosine phosphorylation in the VpsO C-terminal tail represses VPS production and biofilm formation through a mechanism involving the modulation of VpsO oligomerization. We found that tyrosine phosphorylation enhances stability of VpsO. Regulation of VpsO phosphorylation by the phosphatase VpsU is vital for maintaining native VPS levels. This study provides new insights into the mechanism and regulation of VPS production and establishes general principles of biofilm matrix production and its inhibition.

Exceptionally large surface area and well-defined nanostructure are both critical in the field of nanoporous carbons for challenging energy and environmental issues. The pursuit of ultrahigh surface area while maintaining definite nanostructure remains a formidable challenge because extensive creation of pores will undoubtedly give rise to the damage of nanostructures, especially below 100 nm. Here we report that high surface area of up to 3,022 m 2 g −1 can be achieved for hollow carbon nanospheres with an outer diameter of 69 nm by a simple carbonization procedure with carefully selected carbon precursors and carbonization conditions. The tailor-made pore structure of hollow carbon nanospheres enables target-oriented applications, as exemplified by their enhanced adsorption capability towards organic vapours, and electrochemical performances as electrodes for supercapacitors and sulphur host materials for lithium–sulphur batteries. The facile approach may open the doors for preparation of highly porous carbons with desired nanostructure for numerous applications.

Herpesviridae is a diverse family of large and complex pathogens whose genomes are extremely difficult to sequence. This is particularly true for clinical samples, and if the virus, host, or both genomes are being sequenced for the first time. Although herpesviruses are known to occasionally integrate in host genomes, and can also be inherited in a Mendelian fashion, they are notably absent from the genomic fossil record comprised of endogenous viral elements (EVEs). Here, we combine paleovirological and metagenomic approaches to both explore the constituent viral diversity of mammalian genomes and search for endogenous herpesviruses. We describe the first endogenous herpesvirus from the genome of the Philippine tarsier, belonging to the Roseolovirus genus, and characterize its highly defective genome that is integrated and flanked by unambiguous host DNA. From a draft assembly of the aye-aye genome, we use bioinformatic tools to reveal over 100,000 bp of a novel rhadinovirus that is the first lemur gammaherpesvirus, closely related to Kaposi's sarcoma-associated virus. We also identify 58 genes of Pan paniscus lymphocryptovirus 1, the bonobo equivalent of human Epstein-Barr virus. For each of the viruses, we postulate gene function via comparative analysis to known viral relatives. Most notably, the evidence from gene content and phylogenetics suggests that the aye-aye sequences represent the most basal known rhadinovirus, and indicates that tumorigenic herpesviruses have been infecting primates since their emergence in the late Cretaceous. Overall, these data show that a genomic fossil record of herpesviruses exists despite their extremely large genomes, and expands the known diversity of Herpesviridae, which will aid the characterization of pathogenesis. Our analytical approach illustrates the benefit of intersecting evolutionary approaches with metagenomics, genetics and paleovirology.

BACKGROUND: Abnormalities in pyloric development or in contractile function of the pylorus cause reflux of duodenal contents into the stomach and increase the risk of gastric metaplasia and cancer. Abnormalities of the pyloric region are also linked to congenital defects such as the relatively common neonatal hypertrophic pyloric stenosis, and primary duodenogastric reflux. Therefore, understanding pyloric development is of great clinical relevance. Here, we investigated the role of the LIM homeodomain transcription factor Isl1 in pyloric development. RESULTS: Examination of Isl1 expression in developing mouse stomach by immunohistochemistry, whole mount in situ hybridization and real-time quantitative PCR demonstrated that Isl1 is highly expressed in developing mouse stomach, principally in the smooth muscle layer of the pylorus. Isl1 expression was also examined by immunofluorescence in human hypertrophic pyloric stenosis where the majority of smooth muscle cells were found to express Isl1. Isl1 function in embryonic stomach development was investigated utilizing a tamoxifen-inducible Isl1 knockout mouse model. Isl1 deficiency led to nearly complete absence of the pyloric outer longitudinal muscle layer at embryonic day 18.5, which is consistent with Gata3 null mouse phenotype. Chromatin immunoprecipitation, luciferase assays, and electrophoretic mobility shift assays revealed that Isl1 ensures normal pyloric development by directly targeting Gata3. CONCLUSIONS: This study demonstrates that the Isl1-Gata3 transcription regulatory axis is essential for normal pyloric development. These findings are highly clinically relevant and may help to better understand pathways leading to pyloric disease.