The individual and synergistic contributions of two transcription factors, EFG1 and CPH1, have been characterized with regard to adhesion to, and invasion of, human epithelia by Candida albicans. For this purpose two in vitro reconstructed tissue models were developed. A multi-layered model of human epidermis was used to simulate superficial infections of the skin, whereas a reconstructed human intestinal model was used to mimic the first steps of systemic infections. It was shown that C. albicans deleted for both transcription factors CPH1 and EFG1, in contrast to the congenic clinical isolate Sc5314, was neither able to adhere to, nor to penetrate, either of the model systems. A strain deleted for EFG1 alone showed significant reduction in adhesion and was not able to penetrate through the stratum corneum. However, strains deleted for CPH1 showed phenotypes paralleling the phenotypes of the clinical isolate Sc5314. Using different types of multilayered human tissues reconstructed in vitro the individual contributions of Efg1p and Cph1p to two important virulence factors of C. albicans, namely adhesion and invasion, could be defined.

The feasibility to bioengineer a human tissue with an innate vascularization has been shown in vitro and the clinical setting. These results may open the door for the clinical application of various sophisticated bioartificial tissue substitutes and organ replacements.

Chemoelectrical signal transduction in olfactory neurons appears to involve intracellular reaction cascades mediated by heterotrimeric GTP-binding proteins. In this study attempts were made to identify the G protein subtype(s) in olfactory cilia that are activated by the primary (odorant) signal. Antibodies directed against the ␣ subunits of distinct G protein subtypes interfered specifically with second messenger reponses elicited by defined subsets of odorants; odor-induced cAMP-formation was attenuated by G␣ s antibodies, whereas G␣ o antibodies blocked odor-induced inositol 1,4,5-trisphosphate (IP 3 ) formation. Activation-dependent photolabeling of G␣ subunits with [␣- Chemoelectrical signal transduction is considered to be mediated via intracellular reaction cascades triggered by G protein-coupled receptors (1). Biochemical studies over the last decade have revealed that odorants elicit the formation of either cAMP or IP 3 1 in olfactory preparations (2-6). Whereas the functional implications of the dual transduction pathways in the crustacean olfactory system are well established (7,8), in vertebrates the relative importance of the two pathways in olfactory signaling remains controversial (9, 10). Heterotrimeric GTP-binding proteins play a key role in signal transduction processes, coupling activated receptors to the appropriate effector system. A variety of different G␣ subtypes have been identified in vertebrate olfactory epithelium including G s short , G il , G i2 , G i3 , G o , and G q (11-17). Even an olfactory-specific isoform of G s (G olf ) has been discovered (18). However, it is currently unclear how many and which type of G proteins are involved in olfactory signal transduction. To approach the question of which G protein subtype(s) may mediate the transduction processes in olfactory sensory cells, it is necessary to identify the G protein that is activated upon stimulation with distinct odor ligands. This can be accomplished by an activationdependent labeling procedure (19), in which receptor-activated G protein ␣ subunits are photolabeled using the hydrolysisresistant GTP-analogue [␣-32 P]GTP azidoanilide. Subsequent immunoprecipitation of G␣ subunits with subtype-specific antibodies permits identification of G protein subtypes that are labeled upon stimulation of olfactory cilia preparations with distinct odorants. The data indicate that cAMP-and IP 3 -inducing odorants result in labeling of different G protein subtypes. EXPERIMENTAL PROCEDURES MaterialsSprague-Dawley rats were purchased from Charles River, Sulzfeld. The odorants citralva (3,7-dimethyl-2,6-octadiennitrile), hedione (3-oxo-2-pentyl cyclopentaneacetic acid methyl ester), eugenol (2-methoxy-4-(2-propenyl)phenol), lilial (para-butyl-␣-methyl hydrocinnamic aldehyde), lyral (4-(4-hydroxy-4-methyl pentyl)-3-cyclohexene-10-carboxyldehyde), and ethylvanillin (3-ethoxy-4-hydroxybenzaldehyde) were provided by DROM, Baierbrunn. Isovaleric acid (3-methylbutanoic acid) and pyrrolidine (tetrahydropyrrole) were purchased from Sigma. The ra...

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