No abstract

Stigmatella aurantiaca, a species of myxobacteria, produces a novel extracellular signaling molecule, 8‐hydroxy‐2,5,8‐trimethyl‐4‐nonanone, which promotes its developmental cycle. To determine the absolute configuration of this pheromone, which contains one asymmetric carbon, we prepared the R‐ and S‐enantiomers by stereoselective synthesis. The synthesized R‐ and S‐enantiomers each showed nearly the same fruiting body‐inducing activities as the natural pheromone. Gas chromatography‐mass spectrometry (GC‐MS) analysis using a chiral capillary column revealed that the naturally‐produced pheromone is a mixture of both enantiomers.

Halenaquinol sulfu~c, a hydroquinonc sulfate obtuincd from the sponge .%'e.rto.ymgitr .WII)I'N, prevented cell membrane fusion events of cchinadcrm gametes but did not affect early embryonic development offertilized eggs up lo the gastrula stage. However, halenuquinol SUlcd:dw inhibited sccrction of hatching enzyme, resulting in the formation ofgilstrulae that were surrounded by the fertilization cnvclopc. Therefore, the USC ol'halenuquinol sulfate offers a unique opportunity to antrlyzc the role ofsccrctory events in complex populations ofcclls without ilffccting other cellular functions.

Cyl-1 (I)1' and Cyl-2 (2)2~4) are phytotoxic cyclotetrapeptides isolated from a cultured broth of the phytopathogenic fungus, Cylindrocladium scoparium. They have the unique amino acid, Aoe (2-amino-8-oxo-9,10epoxy-decanoic acid) as a component. The configurations at the a-position of each four amino acids of Cyl-1 and Cyl-2 have been determined by physicochemical data or enzymatic reactions,1A) but the stereochemistry of the epoxide of Aoe remained uncertain. In this paper, we describe the determination of its stereochemistry by CDspectra. After the isolation of Cyl-2,2) several tetrapeptides