Fumonisins B1 (FBR) and B2 (FB2), two structurally related mycotoxins with cancer-promoting activity, were recently isolated from corn cultures of Fusarium moniliforme MRC 826. These toxins have been reported to be produced also by isolates of F. proliferatum. Contamination of foods and feeds by F. moniliforme has been associated with human esophageal cancer risk, and FB, has been shown to be the causative agent of the neurotoxic disease leukoencephalomalacia in horses. Because of the toxicological importance of the fumonisins, the potential to produce FBI and FB2 was determined in a study of 40 toxic Fusarium isolates representing 27 taxa in 9 of the 12 sections of Fusarium, as well as two recently described species not yet classified into sections. With the exception of one isolate of F. nygamai, fumonisin production was restricted to isolates of F. moniliforme and F. proliferatum, in the section Liseola. The F. nygamai isolate produced 605 ,ug of FB1 g1-and 530 ,ug of FB2 g-', and the identity of the toxins was confirmed by capillary gas chromatography-mass spectrometry. This is the first report of the production of the fumonisins by F. nygamai.

Corn cultures (five isolates each of Fusarium graminearum Group 1 from wheat crowns, Group 2 from scabby wheat grains and from ear rot of corn and five isolates of F. crookwellense) were screened for their ability to produce deoxynivalenol (DON), nivalenol (NIV), fusarenon-x (FUS-X) and zearalenone (ZEA). Nine of the ten F. graminearum isolates from wheat produced DON (5-165 micrograms g-1) but none produced either NIV or FUS-X. Conversely, 3/5 and 2/5 of the F. graminearum isolates from corn produced NIV (5-40 micrograms g-1) and FUS-X (5-7 micrograms g-1), respectively, while none produced DON. All but one of the F. graminearum isolates produced ZEA (2-1160 micrograms g-1). None of the F. crookwellense isolates produced DON, but 5/5 and 4/5 produced NIV (6-170 micrograms g-1) and FUS-X (3-90 micrograms g-1), respectively, and all produced ZEA (605-1030 micrograms g-1). The results confirmed previous findings on the presence of two distinct F. graminearum chemotypes.

Ethoxyethyne reacts easily with diphenylketene. I. T h e nature of the product depends upon the reaction temperature and the solvent. In benzene at room temperature, a 34 yo yield of l-,phenyl-2-ethoxy-4-hydroxynaphthalene, VI, is obtained, whereas in nitromethane a t -20" the product is l.ldiphenyl-2-ethoxycyc/obut-2-ene-4-one, XXX. These structures have been proved by several reactions and by synthesis of degradation products. Similar reactions have been performed between l-ethoxy-l-propyne (Xxxnr. R = CPHS), 1-methoxy-l-propyne (XXXIV, R = CHs) and dmiphenylketene. I, yielding again a cyclobutenone, X X X V , and a naphthol,

Ethoxyacetylene slowly adds phenyl isocyanate to yield 4-ethoxy2quinolone I (R=H). A similar reac,tion occurs with p-tolyl isocyanate.From the Grignard derivative of ethylfihioacetylene and phenyl isocyanate the anilide of et,hylthiopropynoic acid W I I is obtained. T,he corresponding reaction with ethoxyacetylene does not yield a pure product.In the course of our investigations into ,the reactivity of acetylenic ethers we have also studied the reactions of ethoxyacetylene with aromatic isocyanates.

No abstract