This experiment was conducted to investigate the effect of dietary 1α-hydroxycholecalciferol(1α-OH-D3)in calcium(Ca)-and phosphorous(P)-deficient diets on growth performance, carcass characteristics,tibia related pa...This experiment was conducted to investigate the effect of dietary 1α-hydroxycholecalciferol(1α-OH-D3)in calcium(Ca)-and phosphorous(P)-deficient diets on growth performance, carcass characteristics,tibia related parameters, and immune responses of broiler chickens. A total of 280 one-day-old broiler chickens(Ross 308) were assigned to 20 floor pens and 4 dietary treatments with 5 replicates. Dietary treatments consisted of starter diets(starter diet of treatment A: 1% Ca, 0.73% total phosphorus [tP];starter diet of treatment B: 0.85% Ca.0.64% tP + 5 μg/kg of 1α-OH-D3;starter diet of treatment C: 0.85%Ca, 0.59% tP + 5 μg/kg of 1α-OH-D3;starter diet of treatment D: 0.85% Ca, 0.54% tP + 5 μg/kg of 1α-OHD3), grower diets(grower diet of treatment A: 0.86% Ca, 0.68% tP;grower diet of treatment B: 0.73% Ca,0.59% tP + 5 μg/kg of 1α-OH-D3;grower diet of treatment C: 0.73% Ca, 0.55% tP + 5 μg/kg of 1α-OH-D3;grower diet of treatment D: 0.73% Ca, 0.50% tP + 5 μg/kg of 1α-OH-D3) and finisher diets(finisher diet of treatment A: 0.81% Ca, 0.64% tP;finisher diet of treatment B: 0.68% Ca, 0.56% tP + 5 μg/kg of 1α-OH-D3;finisher diet of treatment C: 0.68% Ca,0,52% tP + 5 μg/kg of 1α-OH-D3;finisher diet of treatment D: 0.68%Ca.0.48% tP + 5 μg/kg of 1α-OH-D3). Results showed that body weight gain(BWG) and feed intake(FI) of broilers in treatment B were similar to those of broilers in treatment A at the end of the trial(P < 0.05).Broilers in treatments C and D had lower BWG and FI than those in treatment A during the whole trial(P < 0.05). Feed conversion ratio, carcass traits and relative weight of lymphoid organs were not affected by dietary treatments(P> 0.05). Dietary treatments had no significant effect on antibody titers against Newcastle and Influenza disease viruses as well as sheep red blood cells. Dietary treatments had no significant effects on tibia ash and tibial dyschondroplasia score. Broilers fed Ca-P deficient diets had lower tibia Ca and P than those in treatment A(P < 0.05). In conclusion, resu展开更多
The search of new substrates with pharmaceutical and industrial potential for biocatalysts including cytochrome P450 enzymes is always challenging. Cytochrome P450 BM3 mutant 139-3, a versatile biocatalyst, exhibited ...The search of new substrates with pharmaceutical and industrial potential for biocatalysts including cytochrome P450 enzymes is always challenging. Cytochrome P450 BM3 mutant 139-3, a versatile biocatalyst, exhibited hydroxylation activities towards fatty acids and alkanes. However, there were limited reports about its hydroxylation activity towards steroids. Herein, an Escherichia coli-based whole-cell extract containing the recombinant 139-3 protein was used as the biocatalyst to screen 13 steroids. Results revealed that 139-3 was able to specifically hydroxylate androstenedione (1) at 1α-position, generating a hydroxylated steroid 1α-OH-androstenedione (1a). To investigate whether C-1α hydroxylation catalyzed by BM3 mutant 139-3 could be industrially used, an optimization of catalyzing conditions was performed. Accordingly, the BM3 mutant 139-3 enzyme was observed to display maximum activity at 37 °C, under pH 7.0 for 4 h, with 37% transformation rate. Moreover, four 139-3 variants were generated by random mutagenesis with the aim of improving its activity and expanding substrate scope. Surprisingly, these mutants, sharing a common mutated site R379S, lost their activities towards androstenedione (1). These data clearly indicated that arginine residue located at site 379 played key role in the hydroxylation activities of 139-3. Overall, these new findings broadened the substrate scope of 139-3 enzyme, thereby expanding its potential applications as a biocatalyst on steroids hydroxylation in pharmaceutical industry.展开更多
基金supported by Islamic Azad University, Isfahan Branch, and resulted from M.Sc. thesis of Parham Ghasemi (grant number:2016/18)
文摘This experiment was conducted to investigate the effect of dietary 1α-hydroxycholecalciferol(1α-OH-D3)in calcium(Ca)-and phosphorous(P)-deficient diets on growth performance, carcass characteristics,tibia related parameters, and immune responses of broiler chickens. A total of 280 one-day-old broiler chickens(Ross 308) were assigned to 20 floor pens and 4 dietary treatments with 5 replicates. Dietary treatments consisted of starter diets(starter diet of treatment A: 1% Ca, 0.73% total phosphorus [tP];starter diet of treatment B: 0.85% Ca.0.64% tP + 5 μg/kg of 1α-OH-D3;starter diet of treatment C: 0.85%Ca, 0.59% tP + 5 μg/kg of 1α-OH-D3;starter diet of treatment D: 0.85% Ca, 0.54% tP + 5 μg/kg of 1α-OHD3), grower diets(grower diet of treatment A: 0.86% Ca, 0.68% tP;grower diet of treatment B: 0.73% Ca,0.59% tP + 5 μg/kg of 1α-OH-D3;grower diet of treatment C: 0.73% Ca, 0.55% tP + 5 μg/kg of 1α-OH-D3;grower diet of treatment D: 0.73% Ca, 0.50% tP + 5 μg/kg of 1α-OH-D3) and finisher diets(finisher diet of treatment A: 0.81% Ca, 0.64% tP;finisher diet of treatment B: 0.68% Ca, 0.56% tP + 5 μg/kg of 1α-OH-D3;finisher diet of treatment C: 0.68% Ca,0,52% tP + 5 μg/kg of 1α-OH-D3;finisher diet of treatment D: 0.68%Ca.0.48% tP + 5 μg/kg of 1α-OH-D3). Results showed that body weight gain(BWG) and feed intake(FI) of broilers in treatment B were similar to those of broilers in treatment A at the end of the trial(P < 0.05).Broilers in treatments C and D had lower BWG and FI than those in treatment A during the whole trial(P < 0.05). Feed conversion ratio, carcass traits and relative weight of lymphoid organs were not affected by dietary treatments(P> 0.05). Dietary treatments had no significant effect on antibody titers against Newcastle and Influenza disease viruses as well as sheep red blood cells. Dietary treatments had no significant effects on tibia ash and tibial dyschondroplasia score. Broilers fed Ca-P deficient diets had lower tibia Ca and P than those in treatment A(P < 0.05). In conclusion, resu
基金supported by the Chinese Academy of Medical Sciences(CAMS)Innovation Fund for Medical Sciences(CIFMS,No.2016-I2M-3–012)the Fundamental Research Funds for the Central Universities of Chinese Academy of Medical Sciences&Peking Union Medical College(2016ZX350001)Beijing Natural Science Foundation(No.7172143)
文摘The search of new substrates with pharmaceutical and industrial potential for biocatalysts including cytochrome P450 enzymes is always challenging. Cytochrome P450 BM3 mutant 139-3, a versatile biocatalyst, exhibited hydroxylation activities towards fatty acids and alkanes. However, there were limited reports about its hydroxylation activity towards steroids. Herein, an Escherichia coli-based whole-cell extract containing the recombinant 139-3 protein was used as the biocatalyst to screen 13 steroids. Results revealed that 139-3 was able to specifically hydroxylate androstenedione (1) at 1α-position, generating a hydroxylated steroid 1α-OH-androstenedione (1a). To investigate whether C-1α hydroxylation catalyzed by BM3 mutant 139-3 could be industrially used, an optimization of catalyzing conditions was performed. Accordingly, the BM3 mutant 139-3 enzyme was observed to display maximum activity at 37 °C, under pH 7.0 for 4 h, with 37% transformation rate. Moreover, four 139-3 variants were generated by random mutagenesis with the aim of improving its activity and expanding substrate scope. Surprisingly, these mutants, sharing a common mutated site R379S, lost their activities towards androstenedione (1). These data clearly indicated that arginine residue located at site 379 played key role in the hydroxylation activities of 139-3. Overall, these new findings broadened the substrate scope of 139-3 enzyme, thereby expanding its potential applications as a biocatalyst on steroids hydroxylation in pharmaceutical industry.
