Genome evolution and plasticity of <em>Serratia marcescens</em>:an important multidrug resistant nosocomial pathogen

Serratia marcescens is an important nosocomial pathogen that can cause an array of infections, most notably of the urinary tract and bloodstream. Naturally, it is found in many environmental niches, and is capable of infecting plants and animals. The emergence and spread of multidrug-resistant strains producing extended-spectrum or metallo beta-lactamases now pose a threat to public health worldwide. Here we report the complete genome sequences of two carefully selected S. marcescens strains, a multidrug-resistant clinical isolate (strain SM39) and an insect isolate (strain Db11). Our comparative analyses reveal the core genome of S. marcescens and define the potential metabolic capacity, virulence, and multidrug resistance of this species. We show a remarkable intraspecies genetic diversity, both at the sequence level and with regards genome flexibility, which may reflect the diversity of niches inhabited by members of this species. A broader analysis with other Serratia species identifies a set of approximately 3,000 genes that characterize the genus. Within this apparent genetic diversity, we identified many genes implicated in the high virulence potential and antibiotic resistance of SM39, including the metallo beta-lactamase and multiple other drug resistance determinants carried on plasmid pSMC1. We further show that pSMC1 is most closely related to plasmids circulating in Pseudomonas species. Our data will provide a valuable basis for future studies on S. marcescens and new insights into the genetic mechanisms that underlie the emergence of pathogens highly resistant to multiple antimicrobial agents

Controlled Terms or Free Terms? A JavaScript Library to Utilize Subject Headings and Thesauri on the Web

There are two types of keywords used as metadata: controlled terms and free terms. Free terms have the advantage that metadata creators can freely select keywords, but there also exists a disadvantage that the information retrieval recall ratio might be reduced. The recall ratio can be improved by using controlled terms. But creating and maintaining controlled vocabularies has an enormous cost. In addition, many existing controlled vocabularies are published in formats less suitable for programming. We introduce a JavaScript library called “covo.js” that enables us to make use of controlled vocabularies as metadata for the organization of web pages

Multi‐Functional MoO3 Doping of Carbon‐Nanotube Top Electrodes for Highly Transparent and Efficient Semi‐Transparent Perovskite Solar Cells

Abstract MoO3 doping of carbon‐nanotube top electrodes in perovskite solar cells is multi‐functional and facilitates p‐doping, favorable energy‐level alignment, and enhanced hole transport. The optimal layer thickness of MoO3 (8 nm) is determined for decreasing the sheet resistance of carbon‐nanotube electrodes without damaging the perovskite film. The sheet resistance decreases by approximately one‐third from its original value, which is a substantially better result than that previously reported for acid doping of carbon‐nanotube top electrodes. MoO3 deposition lowers the Fermi level of the carbon‐nanotube electrode, improving its energy‐level alignment and hole‐transfer performance. When coated with 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (spiro‐MeOTAD), MoO3 crystallizes on the carbon nanotubes and further enhances hole collection. Semi‐transparent perovskite solar cells with MoO3‐doped carbon‐nanotube electrodes have a power conversion efficiency of 17.3% with a transmittance of approximately 60% (at a wavelength of 1000 nm). Because of their favorable transparency in the infrared region, these perovskite solar cells are evaluated for use in a tandem structure with silicon solar cells via computational simulations. The predicted device efficiency (23.7%) exceeds that of conventional indium‐tin‐oxide‐based tandem solar cells (23.0%)

Generation of interleukin-2 receptor gamma gene knockout pigs from somatic cells genetically modified by zinc finger nuclease-encoding mRNA.

Zinc finger nuclease (ZFN) is a powerful tool for genome editing. ZFN-encoding plasmid DNA expression systems have been recently employed for the generation of gene knockout (KO) pigs, although one major limitation of this technology is the use of potentially harmful genome-integrating plasmid DNAs. Here we describe a simple, non-integrating strategy for generating KO pigs using ZFN-encoding mRNA. The interleukin-2 receptor gamma (IL2RG) gene was knocked out in porcine fetal fibroblasts using ZFN-encoding mRNAs, and IL2RG KO pigs were subsequently generated using these KO cells through somatic cell nuclear transfer (SCNT). The resulting IL2RG KO pigs completely lacked a thymus and were deficient in T and NK cells, similar to human X-linked SCID patients. Our findings demonstrate that the combination of ZFN-encoding mRNAs and SCNT provides a simple robust method for producing KO pigs without genomic integration