Insight of Silkworm Pupa Oil Regulating Oxidative Stress and Lipid Metabolism in Caenorhabditis elegans.

Silkworm pupa oil (SPO) contains unsaturated fatty acids, tocopherols, and phytosterols, which can regulate serum total cholesterol or be used as an antioxidant. In this study, we investigated the impacts of SPO on the antioxidant stress and lipid metabolism of Caenorhabditis elegans. The lifespan of the C. elegans fed with different SPO concentrations was determined. The levels of endogenous reactive oxygen species (ROS) were analyzed with the fluorescent probe method. The activity of antioxidant enzymes and the content of malondialdehyde (MDA) were analyzed. The transcription level of specific mRNA was characterized with q-PCR. The survival time of the mutant strain under oxidative stress was determined by daf-2 (CB1370) mutant, sod-3 (GA186) mutant, and skn-1 (EU31) mutant. As for the lipid metabolism, the lipid accumulation was determined with an Oil-Red-O (ORO) staining. The transcription level of specific mRNA was determined by q-PCR. The results showed that the SPO feeding enhanced the activities of antioxidant enzyme by upregulating the expression of the genes skn-1, and sod-3 to decrease the production of ROS and MDA, which prolonged the life of nematodes treated with juglone. ORO staining analysis indicated the feeding of SPO decreased intestinal fat accumulation, downregulated expression of fat-5, fat-6, fat-7, and nhr-80, and upregulated age-1 and tph-1 expression. Conclusively, SPO enhanced the antioxidant capacity by regulating the skn-1 and sod-3 expression of antioxidant gene and reducing the fat accumulation by the insulin/IGF signaling pathway and nuclear hormone receptor nhr-80 signaling pathway of nematodes. This study provides new evidence for the antioxidant and lipid-lowering mechanisms of SPO in C. elegans.

[Relationships between light and physiological characters of five climbing plants].

Studies on the photosynthetic and respiratory rates, light utilization efficiencies and light compensations of five climbing plants showed that the diurnal variations of photosynthetic rates presented double peak, the first peak was between 10:00 to 12:00, and the second was between 14:00 to 16:00. The phenomenon of "noon break" was obvious. The diurnal variations of respiration rates also presented double peak, the first peak was between 11:00 to 13:00, and the second was between 14:00 to 17:00. The light compensation point of Hedera nepatensis, H. helix, Parthenocissus tricuspidata, P. quinuefolia and Wisteria sinensis was 5.73, 5.07, 9.96, 6.40 and 18.93 micromol x m(-2) x s(-1), respectively, and the light utilization efficiency of W. sinensis was higher under strong light, P. quinuefolia was the second, but that of H. helix was higher under weak light. The results showed that Wisteria sinensis was a typical heliophytic plant, Parthenocissus tricuspidata and P. quinuefolia were neuter plants, and Hedera nepalensis and H. helix were typical sciophytic plants.