Analogs of viroidin. Synthesis of four virotoxin-like F-actin binding heptapeptides with one less hydroxyl group in the dihydroxy-proline ring

The vitroxins, toxic cyclic heptapeptides from Amanita virosa fungi, contain a 3,4-dihydroxy-L-proline, an imino acid scarcely accessible in greater amounts. Therefore in the syntheses of the analogs described this imino acid was replaced by 4-cis-hydroxy-L-proline, a component of the analogously toxic phallotoxins. The following syntheses are described: 1a = cyclo (L-alanyl-D-threonyl-D-seryl-L-4-cis-hydroxy-L-prolyl-L-alanyl-2- methylthio-L-tryptophyl-L-leucyl), 1b = 1a but with 2-methylsulfonyl-L-tryptophan in position 6, 2a = cyclic (L-valyl-D-threonyl-D-seryl-4-cis-hydroxy-L-prolyl-L-alanyl-2- methylthio-L-tryptophyl-hydroxyl-L-leucyl), and 2b = 2a, but with 2-methylsulfonyl-L-tryptophan in position 6. In a test for binding strength to rabbit muscle F-actin 2b and 2a exhibited about 40% of that of demethylphalloin. Analogs 1a and 2b have not been tested.     

Bakteriologische Untersuchungsmethoden in der Pilzartendifferenzierung

Zusammenfassung Mittels der Cytochromoxydase-, Oxydase- und Katalase-Reaktion sowie der Benzidinprobe wurden 267 Sprosspilzstämme aus 21 verschiedenen Gattungen auf das Vorhandensein entsprechender Fermente untersucht. Die Auftropfmethode auf Plattenkulturen wurde anderen Verfahren vorgezogen. Positive Cytochromoxydase- und Oxydase-Reaktionen traten meist langsamer auf als bei positiv reagierenden Bakterienstämmen. Innerhalb der meisten untersuchten Pilzgattungen fanden sich wechselnde Ergebnisse. Es bestand auch keine Einheitlichkeit hinsichtlich der Stärke und des zeitlichen Auftretens positiver Reaktionen. Bei 9Lipomyces-Stämmen konnte Cytochromoxydase innerhalb von 15 Tagen nicht nachgewiesen werden, dagegen bei der Mehrzahl derCryptococcus-Kulturen und bei allenTrichosporon- undGeotrichum- Arten. Die Oxydase-Reaktion und Benzidinprobe verhielten sich der Cytochromoxydase-Reaktion nicht analog. Katalase war bei allen Kulturen nachweisbar. Der bei zahlreichen Stämmen beobachtete Mangel der Reproduzierbarkeit der Ergebnisse wird diskutiert.

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Summary The presence of cytochrome oxydase, oxydase, and catalase as well as the benzidine test were studied with 267 yeast strains belonging to 21 different genera. The reagents were preferably applied to the surface of plate cultures after 5 to 15 days of growth at appropriate temperatures. Positive cytochrome oxydase and oxydase reactions developed with the yeasts much slower than with positive bacterial cultures. The results revealed remarkable variations within most of the investigated genera. Likewise the strength of the reaction and the time to become positive varied a great deal even with the same strain. No cytochrome oxydase was found with the methods used in 9 different strains ofLipomyces after 5 to 15 days of observation, but the test became positive with the majority ofCryptococcus strains includingC. neoformans, and with all examined strains of the generaTrichosporon andGeotrichum. The oxydase reaction and the benzidine test did not give results analogous to the cytochrome oxydase reaction. Catalase was found in all cultures. The lacking reproducibility of the findings with numerous strains is discussed.

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Die Untersuchungen wurden mit Mitteln der Deutschen Forschungsgemeinschaft durchgeführt.     

Regeneration of neural crest derivatives in the <Emphasis Type="Italic">Xenopus</Emphasis>tadpole tail

Background  

After amputation of the Xenopus tadpole tail, a functionally competent new tail is regenerated. It contains spinal cord, notochord and muscle, each of which has previously been shown to derive from the corresponding tissue in the stump. The regeneration of the neural crest derivatives has not previously been examined and is described in this paper.