By generating isogenic mutants with a chromosomal in-frame deletion in either inlA or inlB, we have identified InlA and InlB as surface-bound proteins of L. monocytogenes with molecular weights of 88,000 and 65,000, respectively. These results were obtained with monoclonal antibodies raised against either protein and corroborated by N-terminal end sequencing of InlA and InlB. By immunoblot analysis, the production of both polypeptides was found to be strongly dependent on growth temperature and, particularly for InlB, on the presence of the PrfA regulator protein. Expression of InlA was not strictly dependent on the presence of the PrfA regulator protein. Transcription analysis of the inlAB locus revealed that the inlA gene was transcribed by several promoters, of which only one is PrfA dependent. This PrfA-dependent inlA promoter, which contains two base substitutions within its putative PrfA DNA-binding palindrome, is responsible for transcription of both inlA and inlB genes. A hitherto unrecognized promoter located 51 bp upstream of the GTG start codon of the inlB gene was also detected. Hence, inlA and inlB are transcribed both individually and in an operon by PrfA-dependent and-independent mechanisms. Tissue culture invasion assays employing various epithelial cell lines demonstrated that both InlA and InlB are required for invasion. In vivo studies using the mouse infection model revealed that both internalin mutants were attenuated for virulence.

Voronoi tessellations have been used to model the geometric arrangement of cells in morphogenetic or cancerous tissues, however so far only with flat hypersurfaces as cell-cell contact borders. In order to reproduce the experimentally observed piecewise spherical boundary shapes, we develop a consistent theoretical framework of multiplicatively weighted distance functions, defining generalized finite Voronoi neighborhoods around cell bodies of varying radius, which serve as heterogeneous generators of the resulting model tissue. The interactions between cells are represented by adhesive and repelling force densities on the cell contact borders. In addition, protrusive locomotion forces are implemented along the cell boundaries at the tissue margin, and stochastic perturbations allow for non-deterministic motility effects. Simulations of the emerging system of stochastic differential equations for position and velocity of cell centers show the feasibility of this Voronoi method generating realistic cell shapes. In the limiting case of a single cell pair in brief contact, the dynamical nonlinear Ornstein-Uhlenbeck process is analytically investigated. In general, topologically distinct tissue conformations are observed, exhibiting stability on different time scales, and tissue coherence is quantified by suitable characteristics. Finally, an argument is derived pointing to a tradeoff in natural tissues between cell size heterogeneity and the extension of cellular lamellae.

The macrolide ketocarbonic acid carolacton (1) was isolated from the myxobacterium Sorangium cellulosum, strainSo ce960, because of its antibiotic activity. Subsequently, carolacton (1) was discovered to be a highly potent agent against biofilms containing the caries‐ and endocarditis‐associated bacterium Streptococcus mutans. The 2D structure of 1 was elucidated by HRMS, IR and 2D NMR spectroscopy. Initially, the stereogenic centres were determined by chemical derivatization in combination with computional methods and finally verified by X‐ray analysis.

Broadband frequency-doubling properties of c-axis oriented zinc oxide (ZnO) nanorod arrays grown by low-temperature chemical bath method on glass substrate were studied. The maximum effective nonlinearity was found to be about 7.5 times higher than that of a type-I beta-barium borate crystal for a pump intensity of 5.5×1010 W/cm2. The angular dependence of second harmonic generation (SHG) was determined experimentally. The measured spectral profile of SHG was found to be in good agreement with theoretical simulations.

Third harmonic generation (THG) of femtosecond laser pulses in sputtered nanocrystalline TiO2 thin films is investigated. Using layers of graded thickness, the dependence of THG on the film parameters is studied. The maximum THG signal is observed at a thickness of 180 nm. The corresponding conversion efficiency is 26 times larger compared to THG at the air-glass interface. For a demonstration of the capabilities of such a highly nonlinear material for pulse characterization, third-order autocorrelation and interferometric frequency-resolved optical gating (IFROG) traces are recorded with unamplified nanojoule pulses directly from a broadband femtosecond laser oscillator.

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We report the generation of programmable two-dimensional arrangements of ultrashort-pulsed fringe-less Bessel-like beams of extended depth of focus (referred to as needle beams) without truncating apertures. A sub-20-fs Ti:sapphire laser and a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) of high-fidelity temporal transfer in phase-only operation mode were used in the experiments. Axicon profiles with ultrasmall conical angles were approximated by adapted gray scale distributions. It was demonstrated that digitized image information encoded in amplitudephase maps of the needle beams is propagated over considerably large distances at minimal cross talk without the need for additional relay optics. This experiment represents a physical realization of Saari's proposal of spatio-temporally nondiffracting "flying images" on a few-femtosecond time scale.

Chemistry and biology meet in the structure elucidation of the antibiotics thuggacins A–C. The absolute configuration of all stereogenic centers in the thuggacins was confirmed through a combination of chemical derivatization, NMR analysis, molecular modeling, and bioinformatic analysis of the thuggacin biosynthetic genes.