Effects of different dietary protein levels on intestinal aquaporins in weaned piglets.

This study was conducted to investigate the relationship between changes in intestinal aquaporins (AQPs) in piglets fed diets with different protein levels and nutritional diarrhoea in piglets. Briefly, 96 weaned piglets were randomly divided into four groups fed diets with crude protein (CP) levels of 18%, 20%, 22% and 24%. The small intestines and colons of the weaned piglets were collected, and several experiments were conducted. In the small intestine, AQP4 protein expression was higher in weaned piglets fed the higher-CP diets (22% and 24% CP) than in those fed the 20% CP diet except at 72 h (p < 0.01). At 72 h, the AQP4 protein expression in the small intestine was lower in the 18% group than in the other three groups (p < 0.01). Under 20% CP feeding, AQP2, AQP4 and AQP9 protein expression in the colons of piglets peaked at certain time points. The AQP2 and AQP4 mRNA levels in the colon and the AQP4 and AQP4 mRNA levels in the distal colon were approximately consistent with the protein expression levels. However, the AQP9 mRNA content in the colon was highest in the 18% group, and the AQP2 mRNA content in the distal colon was significantly higher in the 24% group than in the 20% group. AQP2 and AQP4 were expressed mainly around columnar cells in the upper part of the smooth colonic intestinal villi, and AQP9 was expressed mainly on columnar cells and goblet cells in the colonic mucosa. In conclusion, 20% CP is beneficial to the normal expression of AQP4 in the small intestine, AQP2, AQP4 and AQP9 in the colon of weaned piglets, which in turn maintains the balance of intestinal water absorption and secretion in piglets.

[Instantaneous emission simulation for light-duty diesel vehicle with different driving cycles by CMEM model].

CMEM model for calculating time based instantaneous emission from light duty diesel vehicle and its input parameters were introduced. On-board test data were used to validate the simulation results. The relative error of THC, CO, and NOx are 14.2%, 3.7% and 32.7%, respectively, while the correlation coefficients reach 0.73, 0.72 and 0.87. The instantaneous emissions of the light duty diesel vehicle simulated by CMEM model are strongly coherent with the transient driving cycle in Shanghai. The simulation of instantaneous emissions and fuel economy under the ECE-15 cycle, FTP cycle, Japan 10-15 cycle and the cycle of shanghai arterial road show that the instantaneous emissions decline with the increase of the vehicle speed, especially from 0-10 km x h(-1) to 10-20 km x h(-1). The acceleration process dominated the whole emissions, which contributes over 30% of the total emission, and sometimes it even reaches over 70%. The contributions of shanghai arterial road for idle condition are 40% and 30%, emission factors of CO are 1.3, 1.5 and 1.4 times of ECE-15 cycle, FTP cycle, Japan 10-15 cycle respectively; THC are respectively 1.5, 2.1 and 1.9 times of above cycles; and emission factors of NOx are respectively 1.2, 1.3 and 1.3 times of ECE-15 cycle, FTP cycle and Japan 10-15 cycle. The fuel economy of the light-duty diesel car on shanghai arterial road is the worst, which is 9.56 km x L(-1). The driving cycles used on abroad can not reflect the actual driving conditions in China.