but does not enhance the expression of noninducible genes. Likewise, a 2-deoxy-D-glucose, a nonmetabolized sugar, is also effective. When a deletion was introduced into the virA gene in the region encoding the periplasmic portion of the VirA protein, enhancement by glucose disappeared, but vir expression was induced by acetosyringone in this mutant. These results suggest that these sugars directly enhance a signaling process initiated by phenolic inducers that results in an-increase in expression of the vir genes.

Botrytis cinerea, a phytopathogenic fungus causing serious gray mold disease of many kinds of cultivated plants, produces a plant growth inhibitory substance. The active substance was isolated and identified as abscisic acid (ABA), a wellknown plant hormone. This report described a microbial production of ABA, emphasizing that ABAproduction by this fungus was remarkably enahnced by irradiating the fungus with blue light during the culture. B. cinereal) was cultured on a potato dexrose agar medium at 27°C for seven days either in the dark or under continuous blue light irradiation (Amax 450 ± 50nm, light intensity of 76fffl cm~2).2) The cultured mycelium and agar were macerated with acetone, and the

SynopsisCooligomers and ABA-type block copolymers composed of a hydrophilic monomer, 2-hydroxyethyl methacrylate (HEMA), and a hydrophobic monomer, styrene, were synthesized to study the relation between their microstructure and hydrophilic and hydrophobic functions. Films of cooligomers and ABA-type block copolymers were cast from DMF solutions at 40°C. The wettability, which was determined from the contact angle with water, increased considerably when HEMA mole fraction reached around 0.8 in the cooligomer system and around 0.9 in the ABA-type block copolymer system. The microstructures of the copolymer films were observed by electron microscopy using the osmium tetroxide fixation technique. The morphologic change in the domain structure was observed at an HEMA mole fraction of about 0.8 in the cooligomer system and about 0.9 in the ABA-type block copolymer system. It is suggested that hydrophilic and hydrophobic functions are largely influenced by the state of aggregation of each segment, that is, the size and geometry of the hydrophilic and hydrophobic domains.

Laetisaria arvalis, a soil-dwelling basidiomycete fungus, secretes an allelopathic agent that induces rapid hyphal lysis in several phytopathogenic fungi. The active compound was isolated from chloroform:methanol extracts of L. arvalis mycelia and characterized as a previously unknown hydroxy fatty acid, (Z,Z-9,12-8-hydroxyoctadecadienoic acid.

Pamamycin-607, which showed aerial mycelium-inducing activity, has been isolated from Streptomyces alboniger IFO 12738. At 0.1 A«g/disc it induces aerial mycelia in the aerial mycelium-negative strain of S. alboniger but inhibits growth of the substrate mycelia at 10 g/disc. It also acts as an antibiotic against some fungi and bacteria. When KMnO4was partitioned with pamamycin-607 between benzene and water, MnO4~but no K+ was transferred from the water to the benzene layer; pamamycin-607was thus shown to be a novel anion-transfer antibiotic.Actinomycetes, which produce a number of useful antibiotics, have a life cycle that is complex whencompared with the various procaryotic microorganisms. This life cycle starts with germination of the spores, which then extend filamentous vegetative mycelia (substrate mycelia) on (and into) the agar medium. Subsequently, the hyphae differentiate and grow in the air as aerial mycelia. Spores are produced on each aerial mycelium in most actinomycete species.D Recently, the relation between cytodifferentiation and secondary metabolism in actinomycetes has attracted much attention, a positive correlation having been reported in several species. Both the ability to produce aerial mycelia and an antibiotic is apt to be lost simultaneously whenspecies undergomutation or are cultured at a high temperature.2) A spontaneous mutant of Streptomyces lactamdurans that lacked aerial mycelia failed to produce the antibiotic cephamycin C.3) The A-factor, first isolated from the normal strain of Streptomyces griseus by Khokhlov et al., restored both the ability to produce streptomycin and form spores in a S. griseus strain deficient in these abilities.4) Weare interested in the endogenous regulating substances present during the formation of aerial mycelia in actinomycetes and have expanded our research on the isolation and chemical characterization of these bioactive metabolites. Consequently, we have isolated 2-methyl-4-amino-5-hydroxymethylpyrimidine (toxopyrimidine) from a Streptoverticillium species.5) In the presence of inosine (or other purine bases) it induced formation of aerial mycelia in a spontaneous bald (aerial myceliumnegative) strain of the same species. Wesubsequently found that Ca(OAc)2was the active substance in Streptomyces ambofaciens. Ca2+ induced or accelerated aerial mycelium formation in a wide range of species, and the formation of aerial mycelia naturally or by the addition of CaCl2 was inhibited by ethylene glycol bis(2-aminoethylether) tetraacetic acid (EGTA), a Ca2+ specific chelating reagent. We, in fact, have evidence that Ca2+ has an important function in regulating the formation of aerial mycelia in manyspecies of actinomycetes (M. Natsume et al. ; manuscript in preparation).