The pathogenesis of Clostridium difficile infection

Clostridium difficile is a major problem as the aetiological agent of antibiotic associated diarrhoea. The mechanism by which the bacterium colonises the gut is poorly understood, but undoubtedly involves a myriad of components present on the bacterial surface. The aims of this study were to further define roles for selected surface proteins using a knockout approach, to evaluate the feasibility of surface protein based immunotherapeutics and to obtain structural information using X-ray crystallography. Mutants of cell wall-binding domain (PFam04122) containing proteins CD1036, CD2735, CD2784, Cwp66, CD2791, Cwp84, CD2795 and the flagella cap (FliD) were created. Mutants were characterised with regard to growth, sporulation, toxin production, adhesion in vitro, and, for the Cwp84 mutant, using the in vivo hamster model. The surface-located cysteine protease, Cwp84, was found to play a key role in maturation of the C. difficile S-layer, yet the Cwp84 mutant still caused disease with a similar pathology to the wildtype. Culture supernatant levels of toxin A were increased in CD2735, Cwp66, CD2791, CD2795 and particularly in Cwp84 and FliD 24 hr cultures, while CD2735, Cwp66, CD2791, CD2795 mutants also showed reduced adherence to Caco-2 cells compared to the wild-type. Passively administered immunotherapy, generated to low pH surface protein extracts of the C. difficile R20291 strain, did not protect hamsters from challenge with the cognate strain. Structural studies were undertaken on the surface proteins CD2791, Cwp66 and CD2767. Crystallisation conditions were identified for a recombinant N-terminal domain of CD2767 and an X-ray data set collected to 2 Å, although the structure was not solved by molecular replacement. Together these results further our knowledge of C. difficile surface proteins, although further work is required to identify which surface proteins play key roles in vivo during infection.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Corn Silage Variety Trial Archive

This report features the available corn silage data from 2003-2017. Crop performance testing results are released annually through the activities of SDSU Extension and the South Dakota Agricultural Experiment Station at SDSU

The theory of the exponential differential equations of semiabelian varieties

The complete first order theories of the exponential differential equations of semiabelian varieties are given. It is shown that these theories also arises from an amalgamation-with-predimension construction in the style of Hrushovski. The theory includes necessary and sufficient conditions for a system of equations to have a solution. The necessary condition generalizes Ax's differential fields version of Schanuel's conjecture to semiabelian varieties. There is a purely algebraic corollary, the "Weak CIT" for semiabelian varieties, which concerns the intersections of algebraic subgroups with algebraic varieties.Comment: 53 pages; v3: Substantial changes, including a completely new introductio

Soybean Variety Trial Archive

This report features the available soybean variety trial data from 2003-2017. Crop performance testing results are released annually through the activities of SDSU Extension and the South Dakota Agricultural Experiment Station at SDSU

Corn Hybrid Trial Archive

This report features the available corn data from 2003-2017. Crop performance testing results are released annually through the activities of SDSU Extension and the South Dakota Agricultural Experiment Station at SDSU

Blurred Complex Exponentiation

It is shown that the complex field equipped with the "approximate exponential map", defined up to ambiguity from a small group, is quasiminimal: every automorphism-invariant subset of the field is countable or co-countable. If the ambiguity is taken to be from a subfield analogous to a field of constants then the resulting "blurred exponential field" is isomorphic to the result of an equivalent blurring of Zilber's exponential field, and to a suitable reduct of a differentially closed field. These results are progress towards Zilber's conjecture that the complex exponential field itself is quasiminimal. A key ingredient in the proofs is to prove the analogue of the exponential-algebraic closedness property using the density of the group governing the ambiguity with respect to the complex topology

Draft Genome of a Type 4 Pilus Defective Myxococcus xanthus Strain, DZF1

Myxococcus xanthus is a member of the Myxococcales order within the deltaproteobacterial subdivision. Here, we report the whole-genome shotgun sequence of the type IV pilus (T4P) defective strain DZF1, which includes many genes found in strain DZ2 but absent from strain DK1622

Spring Wheat Variety Trial Archive

Crop performance testing results are released annually through the activities of SDSU Extension and the South Dakota Agricultural Experiment Station at SDSU

Draft Genome Sequence of Myxococcus xanthus Wild-Type Strain DZ2, a Model Organism for Predation and Development

Myxococcus xanthus is a member of the Myxococcales order within the Deltaproteobacteria subdivision. The myxobacteria reside in soil, have relatively large genomes, and display complex life cycles. Here, we report the whole-genome shotgun sequence of strain DZ2, which includes unique genes not found previously in strain DK1622