Effects of yeast extract supplemented in diet on growth performance, digestibility, intestinal histology, and the antioxidant capacity of the juvenile turbot (Scophthalmus maximus).

An 8-week feeding experiment was conducted on the juvenile turbot (Scophthalmus maximus) to evaluate the influence of yeast extract (YE) supplementation in the diet on growth performance, feed utilization, body composition, nutrient digestibility, intestinal histology, and antioxidant capacity. Four experimental diets were formulated with graded levels of yeast extract 0 (YE0), 1% (YE1), 3% (YE3), and 5% (YE5) and fed to turbots (initial body weight: 4.2 ± 0.1 g) with three replicates per diet and 200 fish in each replicate, respectively. The results showed that turbots fed with diets YE1 and YE3 displayed a significantly higher specific growth rate and protein efficiency rate than those fed with diets YE0 and YE5, while the feed conversion ratios in YE1 and YE3 groups were lower than those in YE0 and YE5. Fish fed with diets YE3 and YE5 showed higher body crude protein contents than those in groups YE0 and YE1. The highest apparent digestibility coefficients for dry matter and crude protein, digestive enzyme activities (trypsin, lipase, and amylase), and the height of the intestinal fold were observed in the YE3 group. YE3 treatment displayed a significantly higher superoxide dismutase (SOD) activity than the YE0 group, while the malondialdehyde (MDA) content in YE1 was significantly lower than those in YE0 and YE5. No significant difference was observed in serum physiological and biochemical parameters among all treatments. Overall, appropriate dietary supplementation of the yeast extract could improve the growth performance, digestibility, and antioxidant capacity of the juvenile turbot, and the recommended yeast extract level in the feed is 2.47%.

Comparative Analysis of Physiological Responses and Intestinal Microbiota in Juvenile Soft-Shelled Turtle (Pelodiscus sinensis) Fed Four Types of Dietary Carbohydrates.

A 60 day feeding trial was conducted to evaluate the impacts of dietary carbohydrates with different complexities and configurations on the growth, plasma parameters, apparent digestibility, intestinal microbiota, glucose, and lipid metabolism of soft-shelled turtles (Pelodiscus sinensis). Four experimental diets were formulated by adding 170 g/kg glucose, fructose, α-starch, or cellulose, respectively. A total of 280 turtles (initial body weight 5.11 ± 0.21 g) were distributed into 28 tanks and were fed twice daily. The results showed that the best growth performance and apparent digestibility was observed in the α-starch group, followed by the glucose, fructose, and cellulose groups (p < 0.05). Monosaccharides (glucose and fructose) significantly enhanced the postprandial plasma glucose levels and hepatosomatic index compared to polysaccharides, due to the un-inhibited gluconeogenesis (p < 0.05). Starch significantly up-regulated the expression of the genes involved in glycolysis, pentose phosphate pathway, lipid anabolism and catabolism, and the transcriptional regulation factors of glycolipid metabolism (srebp and chrebp) (p < 0.05), resulting in higher plasma triglyceride levels and lipid contents in the liver and the whole body. The fructose group exhibited a lower lipid deposition compared with the glucose group, mainly by inhibiting the expression of srebp and chrebp. Cellulose enhanced the proportion of opportunistic pathogenic bacteria. In conclusion, P. sinensis utilized α-starch better than glucose, fructose, and cellulose.

Effects of temperature and microwave on the stability of the blast effector complex APikL2A/sHMA25 as determined by molecular dynamics analyses.

Magnaporthe oryzae is the causal agent of rice blast, and understanding how abiotic stress affects the resistance of plants to this disease is useful for designing disease control strategies. In this paper, the effects of temperature and microwave irradiation on the effector complex comprising APikL2A from M. oryzae and sHMA25 from foxtail millet were investigated by molecular dynamics simulations using the GROMACS software package. While the structure of APikL2A/sHMA25 remained relatively stable in a temperature range of 290 K (16.85 °C) to 320 K (46.85 °C), the concave shape of the temperature-dependent binding free energy curve indicated that there was maximum binding affinity between APikL2A and sHMA25 at 300 K-310 K. This coincided with the optimum infectivity temperature, thus suggesting that coupling of the two polypeptides may play a role in the infection process. A strong oscillating electric field destroyed the structure of APikL2A/sHMA25, although it was stable and not susceptible to weak electric fields.