Synthesis of six novel N,N-dialkyl derivatives of spermidine and effects on growth of the fungal plant pathogen Pyrenophora avenae.
Six novel N,N-dialkyl derivatives of spermidine were synthesised and examined for activity against the oat stripe pathogen Pyrenophora avenae. Two of these spermidine analogues, N,N-dimethyl-N1-(3-aminopropyl)-1,3-diaminopropane trihydrochloride (27) and N,N-dimethyl-N1-(3-aminopropyl)-1,4-diaminobutane trihydrochloride (28), reduced radial extension of P. avenae on plates when used at 2 mM, and caused more substantial reductions in fungal growth in liquid culture when used at 1 mM. Preliminary data suggest that neither compound affected polyamine biosynthesis, determined by following the incorporation of label from ornithine into polyamines and examining intracellular polyamine concentrations in fungal tissue.
The effects of polyamine biosynthesis inhibitors on infection of Hordeum vulgare L. by Erysiphe graminis f.sp. hordei Marchal
SUMMARY The effects of the inhibitors of polyamine biosynthesis, 2-difluoromethylornithine (DFMO), (E)-2-(fluoromethyl) dehydroornithine (A-MFMO), (E)-2-(fluoromethyl) dehydroornithine methyl ester (A-MFMO. CH3), 2-hydrazinoornithine, (2R,5R)-6-heptyne-2,5-diamine (RR-MAP), 2-difluoromethylarginine (DFMA), cyclohexylamine (CHA) and methylglyoxal-bis (guanylhydrazone) (MGBG) on infection of barley leaves (Hordeum vulgare L.) by Erysiphe graminis f.sp. hordei Marchal, were examined. Various concentrations of the inhibitors were sprayed onto barley leaves cv. Golden Promise as post-inoculation treatments. DFMO, MGBG and a combination of the two were also applied as pre-inoculation treatments. Each inhibitor substantially reduced mildew infection. DFMO was as efficient as the more recently developed ornithine analogues. With the exception of the DFMA treatments, post-inoculation sprays were more effective than pre-inoculation ones. When DFMO, MGBG and DFMA were sprayed onto leaves at different times, DFMO and MGBG most effectively controlled mildew when sprayed on the third day after inoculation. DFMA was more efficient as a pre-inoculation treatment. Addition of polyamines to DFMO sprays increased mildew infection, compared to that resulting from the DFMO treatment alone, but infection was less than in the controls.
Pioneer 10 Observations of the Ultraviolet Glow in the Vicinity of Jupiter
A two-channel ultraviolet photometer aboard Pioneer 10 has made several observations of the ultraviolet glow in the wavelength range from 170 to 1400 angstroms in the vicinity of Jupiter. Preliminary results indicate a Jovian hydrogen (1216 angstrom) glow with a brightness of about 1000 rayleighs and a helium (584 angstrom) glow with a brightness of about 10 to 20 rayleighs. In addition, Jupiter appears to have an extensive hydrogen torus surrounding it in the orbital plane of Io. The mean diameter of the torus is about equal to the diameter of the orbit of Io. Several observations of the Galilean satellites have also occurred but only a rather striking Io observation has been analyzed to date. If the observed Io glow is predominantly that of Lyman-α, the surface brightness is about 10,000 rayleighs.