In this report, we show that α-amylase activity is rhythmic in the wild-type fruit fly Drosophila melanogaster, and that this rhythm exhibits the properties of a clock output. Moreover, the rhythm of amylase activity is accompanied by fluctuations in the Amy protein level under 12L : 12D conditions. A strong sexual dimorphism is evident in the oscillations of Amy protein and enzymatic activity. Under light : dark (LD) conditions on the control diet, CantonS wild-type Drosophila melanogaster exhibit a bimodal rhythm of amylase activity, particularly of the AmyD3 (Amy3) isoform, with morning and evening peaks. Under these conditions, Amy protein levels also oscillate significantly, again more strongly for the Amy3 isoform than Amy1 (Amy1). A robust oscillation of Amy3 and Amy1 activity is also observed under DD conditions for both sexes. In constant light (LL) the rhythms dampen out, particularly in the males. A high level of dietary glucose causes an overall decrease in the amplitudes of the rhythmic oscillations of amylase activity, but the processes are nevertheless rhythmic, with peak activities at Zt8 for the females, and at Zt0 for the males in LD. In constant darkness (DD) the rhythms are maintained. Mutants lacking a functioning oscillator, per01, exhibit a slight photoperiodicity in LD, with a decrease in amylase activity in both males and females during the late night in LD, but no rhythmic oscillations in DD.
This study investigated the effects of riboflavin on energy metabolism in hypoxic mice. Kunming mice were fed diets containing riboflavin at doses of 6, 12, 24 and 48 mg/kg, respectively for 2 weeks before exposure to a simulated altitude of 6000 m for 8 h. Changes of riboflavin status and energy metabolism were assessed biochemically. Simultaneously, a 1H nuclear magnetic resonance (NMR) based metabolomic technique was used to track the changes of plasma metabolic profiling. It was found that the content of hepatic riboflavin was decreased and erythrocyte glutathione activation coefficient was elevated significantly under hypoxic condition. Meanwhile, increased plasma pyruvate, lactate, β-hydroxybutyrate and urea, as well as decreased plasma carnitine were observed. Riboflavin supplementation improved riboflavin status remarkably in hypoxic mice and decreased plasma levels of pyruvate, free fatty acids and β-hydroxybutyrate significantly. Plasma carnitine was increased in response to riboflavin supplementation. Results obtained from 1H NMR analysis were basically in line with the data from biochemical assays and remarkable changes in plasma taurine, choline and some other metabolites were also indicated. It was concluded that riboflavin requirement was increased under acute hypoxic condition and riboflavin supplementation was effective in improving energy metabolism in hypoxic mice., Y. P. Wang, J. Y. Wei, J. J. Yang, W. N. Gao, J. Q. Wu, C. J. Guo., and Obsahuje bibliografii