Derivation of stable embryonic stem cell-like,but transcriptionally heterogenous,induced pluripotent stem cells from non-permissive mouse strains

Mammalian Genome - Genetic background is known to play a role in the ability to derive pluripotent, embryonic stem cells (ESC), a trait referred to as permissiveness. Previously we demonstrated...     

Agri-environment conservation set-asides have co-benefits for connectivity

Widespread declines in farmland biodiversity have led to state-funded schemes which take land out of production to create (semi-)natural habitats for biodiversity (e.g. EU agri-environment schemes; US Conservation Reserve Program). Common features of such schemes are grassland strips at the edges of agricultural fields, and we examine potential co-benefits of these biodiversity set-asides for contributing to grassland connectivity. Although set-aside strips had negligible impact on landscape-scale species persistence (using metapopulation models parameterized for flying insects run on 267 landscapes of ~30 000 ha across England), they nonetheless improved connectivity in 74% (198/267) of landscapes (comparing landscapes with and without set-asides), as shown by range expansion rates increasing by up to 100%. Benefits of set-aside strips varied according to species type (high/low dispersal, high/low population density), but had little benefit for species with low dispersal and small population sizes, which generally failed to expand. High dispersal/high density species were already successful expanders regardless of set-asides (> 75% of simulations were successful without set-asides) although expansion rates were still improved when set-asides were added. Whilst alternative strategies for placement of set-aside strips (more/less aggregated), revealed no consensus ‘better’ strategy across species types, set-aside benefits were generally greatest in landscapes with intermediate availability of semi-natural grassland (0.5-4% cover). We conclude that small-scale set-asides have the potential to improve connectivity, which we expect to help some species track climate change, and connect habitat patches within existing climate space for others. However, set-asides are unlikely to benefit low dispersal species which are probably at greatest risk from agricultural intensification.     

Marine metagenomics: strategies for the discovery of novel enzymes with biotechnological applications from marine environments

Metagenomic based strategies have previously been successfully employed as powerful tools to isolate and identify enzymes with novel biocatalytic activities from the unculturable component of microbial communities from various terrestrial environmental niches. Both sequence based and function based screening approaches have been employed to identify genes encoding novel biocatalytic activities and metabolic pathways from metagenomic libraries. While much of the focus to date has centred on terrestrial based microbial ecosystems, it is clear that the marine environment has enormous microbial biodiversity that remains largely unstudied. Marine microbes are both extremely abundant and diverse; the environments they occupy likewise consist of very diverse niches. As culture-dependent methods have thus far resulted in the isolation of only a tiny percentage of the marine microbiota the application of metagenomic strategies holds great potential to study and exploit the enormous microbial biodiversity which is present within these marine environments.     

Strain persistence of invasive Candida albicans in chronic hyperplastic candidosis that underwent malignant change

Objectives: The aim of this study was to assess persistence and tissue invasion of Candida albicans strains isolated from a 65 year‐old patient with chronic hyperplastic candidosis (CHC), that subsequently developed into squamous cell carcinoma (SCC). Materials and Methods: C. albicans (n=7) were recovered from the oral cavity of the patient over seven years. Confirmation of CHC and SCC in this patient was achieved by histopathological examination of incisional biopsy tissue. DNA fingerprinting was performed on the seven isolates from the CHC patient together with a further eight isolates from patients with normal oral mucosa (n=2), chronic atrophic candidosis (n=1), SCC (n=1) and CHC (n=4). Genotyping involved the use of inter‐repeat PCR using the eukaryotic repeat primer 1251. Characterisation of the tissue invasive abilities of the isolates was achieved by infecting a commercially available reconstituted human oral epithelium (RHE; SkinEthic, Nice, France). After 24 h. C. albicans tissue invasion was assessed by histopathological examination. Results: DNA fingerprinting demonstrated strain persistence of C. albicans in the CHC patient over a seven year period despite provision of systemic antifungal therapy. The strain of C. albicans isolated from this patient was categorised as a high invader within the RHE compared to other isolates. Conclusions: Candidal strain persistence was evident in a patient with CHC over seven years. This persistence may be due to incomplete eradication from the oral cavity following antifungal therapy or subsequent recolonisation from other body sites or separate exogenous sources. The demonstration of enhanced in vitro tissue invasion by this particular strain may, in part, explain the progression to carcinoma.     

Synthesis and characterisation of polyamine-poly(ethylene glycol) constructs for DNA binding and gene delivery

Improved non-viral vector systems are needed for efficient delivery of DNA to target cell nuclei in gene therapy. A series of linear polyamine poly(ethylene glycol) (PEG) constructs has been synthesised by reaction of appropriately Boc-protected thermine derivatives with omega-methoxyPEG oxiranylmethyl ethers. Constructs carrying 1-3 MeOPEG units and 0, 2 or 4 N-methyl groups have been prepared by this method. H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NHBoc was prepared efficiently by mono-trifluoroacetylation of thermine, attachment of Boc and removal of the trifluoroacetyl group in one pot. A similar process gave H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NH2. BocMeN(CH2)3NHMe was alkylated by 1,3-dibromopropane to give BocMeN(CH2)3NMe(CH2)3NMe(CH2)3NMeBoc. A cyanoethylation/reduction sequence extended H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NH2 to give H2N(CH2)3NBoc(CH2)3NBoc(CH2)3NBoc(CH2)3NBoc(CH2) 3NH2, which was converted to its mono- and di-MeOPEG550 derivatives. Deprotection gave the linear polyamine MeOPEG constructs. A branched triamine-poly(ethylene glycol) construct was prepared by acylation of (BocHN(CH2)3)2N(CH2)3NH2 with omega-methoxyPEG 550 chloroformate, followed by deprotection. A cyanoethylation/reduction/protection sequence from (H2N(CH2)3)2 N(CH2)3NHBoc gave a protected pentamine. Alkylation with Br(CH2)5CONH(CH2)2NHBoc, deprotection, acylation with MeOPEG chloroformate and deprotection gave a pentamine MeOPEG construct in which the MeOPEG is attached through a linker to the central amine. The linear hexamine construct carrying MeOPEG550 at only one terminus was the most effective DNA-interactive member of the two series in an ethidium displacement assay and was effective in delivering a reporter gene to RIF-1 tumours.     

Bayesian multiple quantitative trait loci mapping for complex traits using markers of the entire genome

A Bayesian methodology has been developed for multiple quantitative trait loci (QTL) mapping of complex binary traits that follow liability threshold models. Unlike most QTL mapping methods where only one or a few markers are used at a time, the proposed method utilizes all markers across the genome simultaneously. The outperformance of our Bayesian method over the traditional single-marker analysis and interval mapping has been illustrated via simulations and real data analysis to identify candidate loci associated with colorectal cancer.     

Time-dependence and preliminary SAR studies in inhibition of nitric oxide synthase isoforms by homologues of thiocitrulline

Treatment of N(alpha)-Cbz-N(epsilon)-(2-hydroxyethylaminothiocarbonyl)-L-lysine N-(2-hydroxyethyl)amide with boiling hydrochloric acid gave N(epsilon)-(4,5-dihydrothiazol-2-yl)-L-lysine. This was a weak and non-isoform selective inhibitor of NOS, whereas N(epsilon)-aminothiocarbonyl-L-lysine and its methyl ester were potent, with IC(50)=13 and 18 microM, respectively, against human iNOS and IC(50)=3 and 8 microM, respectively, against rat nNOS. Time dependence was observed for inhibition of nNOS by the ester.