Many herbivorous insects sequester defensive chemicals from their host plants. We tested sequestration fitness costs in the specialist moth Utetheisa ornatrix (Lepidoptera: Arctiidae). We added pyrrolizidine alkaloids (PAs) to an artificial diet at different concentrations. Of all the larval and adult fitness components measured, only development time was negatively affected by PA concentration. These results were repeated under stressful laboratory conditions. On the other hand, the amount of PAs sequestered greatly increased with the diet PA concentration.
The nature of the denitrosation of nitrosamines by rat liver microsomes was investigated. The rates of NADPH-dependent nitrosamine demethylation and denitrosation were compared in the same incubation mixture using several types of microsomes and inhibitors. Pretreatment with isopropanol, pyrazole, phenobarbital, and 3-methylcholanthrene had parallel effects on the microsomal demethylation and denitrosation reactions.
The effects of riboflavin deficiency on the metabolism of N-nitrosodimethylamine [(DMN) CAS: 62-75-9] and other nitrosamines were examined in rats. After weanling rats were put on a riboflavin-deficient diet, the development of the deficiency was monitored by the growth rate and the erythrocyte glutathione reductase activation coefficient. In the riboflavin-deficient rats, the liver microsomal NADPH-cytochrome c reductase activity was lower but the cytochrome P450 content was higher than that of the control. The metabolism of DMN was dependent on the severity of the deficiency.
Herba epimedii (Epimedium), a traditional Chinese medicine, has been widely used as a kidney tonic and antirheumatic medicine for thousands of years. The bioactive components in herba epimedii are mainly prenylated flavonol glycosides, end-products of the flavonoid pathway. Epimedium species are also used as garden plants due to the colorful flowers and leaves. Many R2R3-MYB transcription factors (TFs) have been identified to regulate the flavonoid and anthocyanin biosynthetic pathways.