Occurrence and characteristics of group 1 introns found at three different positions within the 28S ribosomal RNA gene of the dematiaceous Phialophora verrucosa: phylogenetic and secondary structural implications

<p>Abstract</p> <p>Background</p> <p>Group 1 introns (ribozymes) are among the most ancient and have the broadest phylogenetic distribution among the known self-splicing ribozymes. Fungi are known to be rich in rDNA group 1 introns. In the present study, five sequences of the 28S ribosomal RNA gene (rDNA) regions of pathogenic dematiaceous <it>Phialophora verrucosa </it>were analyzed using PCR by site-specific primers and were found to have three insertions, termed intron-F, G and H, at three positions of the gene. We investigated the distribution of group 1 introns in this fungus by surveying 34 strains of <it>P. verrucosa </it>and seven strains of <it>Phialophora americana </it>as the allied species.</p> <p>Results</p> <p>Intron-F's (inserted at L798 position) were found in 88% of <it>P. verrucosa </it>strains, while intron-G's (inserted at L1921) at 12% and intron-H's (inserted at L2563) at 18%. There was some correlation between intron distribution and geographic location. In addition, we confirmed that the three kinds of introns are group 1 introns from results of BLAST search, alignment analysis and Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). Prediction of secondary structures and phylogenetic analysis of intron sequences identified introns-F and G as belonging to subgroup IC1. In addition, intron-H was identified as IE.</p> <p>Conclusion</p> <p>The three intron insertions and their insertion position in the 28S rDNA allowed the characterization of the clinical and environmental isolates of <it>P. verrucosa </it>and <it>P. americana </it>into five genotypes. All subgroups of introns-F and G and intron-H were characterized and observed for the first time in both species.</p

Therapeutic targets in rheumatoid arthritis: the interleukin-6 receptor

RA is a chronic, debilitating disease in which articular inflammation and joint destruction are accompanied by systemic manifestations including anaemia, fatigue and osteoporosis. IL-6 is expressed abundantly in the SF of RA patients and is thought to mediate many of the local and systemic effects of this disease. Unlike a number of other cytokines, IL-6 can activate cells through both membrane-bound (IL-6R) and soluble receptors (sIL-6R), thus widening the number of cell types responsive to this cytokine. Indeed, trans-signalling, where IL-6 binds to the sIL-6R, homodimerizes with glycoprotein 130 subunits and induces signal transduction, has been found to play a key role in acute and chronic inflammation. Elevated levels of IL-6 and sIL-6R in the SF of RA patients can increase the risk of joint destruction and, at the joint level, IL-6/sIL-6R can stimulate pannus development through increased VEGF expression and increase bone resorption as a result of osteoclastogenesis. Systemic effects of IL-6, albeit through conventional or trans-signalling, include regulation of acute-phase protein synthesis, as well as hepcidin production and stimulation of the hypothalamo-pituitary-adrenal axis, the latter two actions potentially leading to anaemia and fatigue, respectively. This review aims to provide an insight into the biological effects of IL-6 in RA, examining how IL-6 can induce the articular and systemic effects of this disease

State of the art on gate insulation and surface passivation for GaN-based power HEMTs

In this article, we review recent progress on AlGaN/GaN and InAlN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) using Al-based oxides, nitride dielectrics, SiO2 and high-k dielectrics. Although GaN MIS-HEMTs have been suffering from the instability of threshold voltage (V-TH), recent interface technologies using in-situ SiNx and surface oxidation of (Al)GaN achieved excellent DC and dynamic performances of GaN MIS-HEMTs with stable V-TH. Furthermore, a new design of the gate dielectric such as a nanolaminate structure has been applied to GaN HEMTs. GaN-based MIS-HEMTs sometimes showed sudden current saturation at forward gate bias, and we discuss effects of electronic states at insulator-semiconductor interfaces on current linearity of GaN MIS-HEMTs. Finally, we present effective surface passivation schemes in conjunction with field-plate structures and emerging device structures utilizing multi nanochannels under the gate region