Distribution of substituents in O-(2-hydroxyethyl)cellulose

The distribution of substituents in four samples of O-(2-hydroxyethyl)cellulose has been investigated by methylation analysis. One sample was commercial and the others were prepared under conditions analogous to those used industrially during the hydroxyethylation step in the manufacture of O-ethyl-O-(2-hydroxyethyl)cellulose. The results indicate that the distribution of substituents is similar to that expected for a homogeneous reaction.     

Rough mutants of Salmonella typhimurium: immunochemical and structural analysis of lipopolysaccharides from rfaH mutants

Lipopolysaccharides, extracted by phenol/chloroform/petroleum ether, from two rough mutants of Salmonella typhimurium of class rfaH were studied by passive haemagglutination inhibition and by methylation analysis. The structural and immunochemical analyses showed that (i) formation of the galactose I unit of the core is defective, but the defect is not complete, and (ii) of those core chains which do receive the galactose I residue, many are not continued to form complete core, but instead terminate at intermediate points. This suggests that the rfaH gene, though involved in formation of the galactose I unit, is not the structural gene for the galactosyltransferase which adds this unit. The rfaH product may be a positive regulator for several rfa genes specifying glycosyltransferases, or it may be a protein needed for the efficient action of several such transferases.     

Photosystem I Is an Early Target of Photoinhibition in Barley Illuminated at Chilling Temperatures

Light-induced damage to photosystem I (PSI) was studied during low-light illumination of barley (Hordeum vulgare L.) at chilling temperatures. A 4-h illumination period induced a significant inactivation of PSI electron transport activity. Flash-induced P700 absorption decay measurements revealed progressive damage to (a) the iron-sulfur clusters F_A and F_B, (b) the iron-sulfur clusters F_A, F_B, and F_X, and (c) the phylloquinone A₁ and the chlorophyll A₀ or P700 of the PSI electron acceptor chain. Light-induced PSI damage was also evidenced by partial degradation of the PSI-A and PSI-B proteins and was correlated with the appearance of smaller proteins. Aggravated photodamage was observed upon illumination of barley leaves infiltrated with KCN, which inhibits Cu,Zn-superoxide dismutase and ascorbate peroxidase. This indicates that the photodamage of PSI in barley observed during low-light illumination at chilling temperatures arises because the defense against active oxygen species by active oxygen-scavenging enzymes is insufficient at these specific conditions. The data obtained demonstrate that photoinhibition of PSI at chilling temperatures is an important phenomenon in a cold-tolerant plant species.     

Evaluation of trichothecene and nontrichothecene mycotoxins produced byFusarium in soybeans

Each of 12 cultures ofFusarium, comprising four species, isolated from moldy soybeans suspected of being involved in illness of wild geese, were grown separately in autoclaved moist rice, in autoclaved moist soybeans, and in surface sterilized-disinfected soybeans, assayed for various mycotoxins, and fed to rats. Four additional cultures that produced known toxins on rice were also grown on soybeans as controls. All isolates, except one ofF moniliforme, grown in rice resulted in weight loss of rats, and that one resulted in weight gain; 12 of the isolates caused death. One isolate ofF poae grown in soybeans caused death when consumed by rats, but none of the other 15 resulted in weight loss or overt injury. Much larger amounts of zearalenone, deoxynivalenol (DON), T-2 toxin, neosolaniol, T-2 tetraol, wortmannin, and moniliformin were produced by the cultures on rice than on soybeans, but more HT-2 toxin was produced by one isolate ofF poae grown on soybeans than when grown on rice. Soybeans appear to be a poor substrate for elaboration of most of the toxins produced by the isolates tested.