An antifungal activity against Mucorhiemalis was detected in the culture broth of Sorangium cellulosum (Myxococcales) strain So ce90. The activity was excreted into the supernatant during the log and early stationary phase. Whenthe adsorber resin XAD-16was added to the culture, the active metabolites were quantitatively bound to the resin. The epothilons showed a high cytotoxicity for animal cells and mimic the biological effects oftaxol (Bollag et al, Cancer Res. 55: 2325~2333, 1995).In our screening program for secondary metabolites from myxobacteria, we detected metabolites with a narrowantifungal spectrum: they were inhibitory for Mucor hiemalis only. They were first seen in the culture broth of Sorangium cellulosum strain So ce90 and turned out to be novel macrocyclic polyketides1}.

How similar must a compound be to taxol in order to displace it from its binding site on microtubules? The microbial secondary metabolites epothilones A (1a) and B (1b) provide an answer to this question. These comparatively small, simply constructed, and highly cytotoxic macrolides surprisingly show no similarity to taxol, according to X‐ray and NMR spectroscopic results.

Ever since the first meeting of the proponents of the emerging Logical Empiricism in 1923, there existed philosophical differences as Experience and prediction: an analysis of the foundations and. Apr 30, 2006. Experience and Prediction: An Analysis of the Foundations and the Structure of Knowledge. Paperback-English. By Reichenbach, Hans ?Meaning rrriry bc asked how such a new attempt at a foundation of. tlrc irrrportance attributed to linguistic analysis, the con-. The probability structure of knowledge. Experience and prediction Open Library An Analysis of the Foundations and the Structure of Knowledge. "Hans Reichenbach's Experience and Prediction is one of the most important books in Experience and Prediction. An Analysis of the Foundations-JStor 3.3 Tools to uncover and reflect on the subjective nature of knowledge Addressing subjectivity and reflexivity appears to be a rather ambiguous task especially when we consider our experience of working on the FQS issues. Experience and Prediction.

What are myxobacteria?Myxobacteria are Gram-negative eubacteria with relatively large (0.6-1.2 by 3-15 m) rod-shaped cells. They live in soil and related habitats and are famous for three capabilities: (i) they move by gliding and their colonies are therefore thin, film-like swarms that spread gradually over the culture plate; (ii) they have sophisticated intercellular communication systems and a highly developed social life; and (iii) they show a remarkable morphogenetic potential, which is expressed on two levels. In a co-operative morphogenesis involving 10 5 -10 6 cells, induced by starvation conditions, they may produce a fruiting body. Within the maturing fruiting body, a cellular morphogenesis takes place, during which the vegetative cells convert into desiccation-resistant myxospores. It might also be mentioned that myxobacteria have the largest genomes of all bacteria (9500-10 000 kbp) and a DNA with a G þ C content of 66-72 mol%. Details can be found in several reviews (Reichenbach and

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Newcytostatic compounds, tubulysins, were isolated from the culture broth of strains of the myxobacteria Archangium gephyra and Angiococcus disciformis. The compounds are peptides partly consisting of unusual amino acids and are distantly related to the dolastatins. The tubulysins were not active against bacteria and only little against fungi, but showed high cytostatic activity against mammaliancell lines with IC50 values in the picomolar range. An incubation with 50ng/ml tubulysin A led to a complete disappearance of the microtubuli network of the cells within 24 hours. The more active tubulysin D induced multipolar spindles: At 0.5 ng/ml all mitotic cells showed more than four spindle poles.During our screening for new, biologically active metabolites from myxobacteria, we found in the culture broth of different strains of Archangium gephyra activities that were highly cytotoxic for L929 mouse flbroblasts. Bioassay-guided fractionation of culture extracts showed that the activities were due to a group of novel compounds which we called tubulysins. Later, we also found these compoundsin certain strains of the genera Angiococcus, Cystobacter, and Stigmatella. In this paper we describe the production, isolation, and the physico-chemical and biological properties of the tubulysins. Fig. 1 shows the structures of the tubulysins isolated so far, the elucidation of which will be published elsewhere1). The tubulysins are peptides that contain unusual amino acids. The tubulysins A and B have a hydroxyl group on C-31, in contrast to the tubulysins D and E. The tubulysins are distantly related to the dolastatins, which were isolated from the marine slug, Dolabella auricularia2\

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