No abstract

Ascorbic acid (AA), dehydroascorbic acid (dehydroAA), isoascorbic acid (isoAA), ascorbic acid-Z-phosphate @A-2-PO& and ascorbic acid-2-sulfate (AA-2-SOJ were tested as inhibitors of mushroom polyphenoloxidase (PPO). Kinetic analysis indicated that AA and isoAA were more effective than dehydroAA. The half times (tr,J that decreased 50% of PPO activity for AA, isoAA and dehydroAA were 2.5,3.1, and 1.9 hr, respectively, and the concentrations that inhibited half of PPO activity were as follows: ascorbic acid, 0.04 mM, isoAA, 0.25 mM; and dehydroAA, 7.5 mM. Electron spin resonance studies demonstrated that the Cuz+ of PPO was reduced to Cu+ by AA. AA-2-PO, and AA-2-SO4 were not inhibitors for PPO. However, the digestion of AA-2-PO4 with acid phosphatase yielded AA to inhibit PPO activity. AA-2-SO4 was found to be a poor substrate for sulfatase.

No abstract

The allelopathic interaction between sorghum [Sorghum bicolor (L.) Moench] and 10 species of grass and broadleaf weeds was investigated. Germination of weed seeds was slightly inhibited or stimulated, depending on species, when incubated in closed Petri dishes with germinating sorghum. Subsequent radicle and hypocotyl or coleoptile elongation of weeds was significantly inhibited by the germinating sorghum. For weeds interplanted with sorghum and grown under greenhouse conditions. The inhibitory effect on some weed species was still evident after 2 months of growth. Significant differences were found in the dry matter per weed plant grown in pots in proximity to sorghum vs. weeds grown in monoculture. Aqueous leachates from pots planted with sorghum alone or from a system in which sorghum roots protruded into water had strong allelopathic activity. These results indicate that water-soluble allelochemicals are produced by germinating sorghum seeds and that production of these substances continues during seedling growth.

LIEB, BILLS, SINNHUBER fecal tritium curve rather than to the urine curve. AFMi is apparently associated with the protein fraction in milk (Allcroft and Carnaghan, 1963). AFMi may also associate with protein fractions in the ruminal environment and be carried through the intestine in a form similar to that secreted in milk. According to AFMi analysis, the content in milk increased up to 3 or 4 days during chronic dosing at which time it plateaued. The radioactive secretion in milk reflects a similar pattern. Considering both radioactivity and chemical analysis, milk is obviously not a principal excretory route for aflatoxin. Evaluation of total distribution patterns is not possible with these data in that labeled materials by all excretory routes after 96 hr ac-