No abstract

No abstract

Summary Livestock and laboratory animals show compensatory growth when they are fed ad libitum following a period of restriction feeding. Lysine is a major limiting essential amino acid in the diets both for humans and animals. We hypothesized that changing dietary lysine levels from deficient to sufficient induced compensatory growth in young rats. We elucidated the effect of lysine sufficiency on the dynamics of hormones, relevant to muscle protein synthesis and degradation, insulin-like growth factor-I (IGF-I) and corticosterone, and on the expression of proteolytic-related genes in skeletal muscle during compensatory growth. Lysine sufficiency where the dietary lysine level was increased from 0.46% to 1.30% after 2 wk of subjecting the rats to the lower lysine level induced 80% enhancement of growth rate of rats. During compensatory growth with the lysine sufficiency, fractional muscle protein synthesis rates were higher whereas fractional muscle protein degradation rates were lower than those of the control group ( p Ͻ 0.05). After lysine sufficiency, the expression of atrogin-1/MAFbx mRNA was decreased in gastrocnemius muscle ( p Ͻ 0.05). With the lysine sufficiency, serum IGF-I concentration increased ( p Ͻ 0.05) whereas serum corticosterone decreased ( p Ͻ 0.05). These findings suggest that compensatory growth with lysine sufficiency is due to a change of hormone levels before and after changing diets, resulting in incrementation of protein synthesis and suppression of protein degradation of skeletal muscle. Key Words compensatory growth, lysine, rat, IGF-I, corticosteroneOne of the important subjects in nutritional science is to elucidate how humans and animals respond and adapt to transitions of nutritional status and changes of metabolic reaction that occur during the adaptation.There are numerous reports about adaptation of animals to excess or deficiency of nutrients or energy in diets. Compensatory growth is an example of adaptation to nutritional status. Livestock and laboratory animals show compensatory growth when they are fed ad libitum following a period of restricted feeding or fed adequate energy following a period of energy restriction ( 1-3 ). Previous studies in rats and pigs showed that when animals that had been fed a protein-free or a low protein diet were refed a diet containing a sufficient amount of protein, they developed faster than animals fed a control diet particularly for the first few days after the diet replacement ( 4-6 ). Promoted protein accumulation during compensatory growth is due to a larger difference between the rate of muscle protein synthesis and the rate of muscle protein degradation compared to normal growth. The phenomenon has been considered a transitional state in adapting to the nutritional status. Both anabolic and catabolic hormones may be involved in this response. All of these previous studies indicate that sufficiency of dietary protein and amino acid levels plays a role as a trigger for compensatory growth in animals. However, these studies provide no ...

No abstract

Power generation by roof-mounted photovoltaic (PV) modules may provide additional income to farmers if the crop production is comparable to production under normal greenhouse conditions. However, fluctuating irradiance caused by the partial shade of PV modules has been reported to reduce crop production. In the present study, we have shown for the first time the possibility of improving lettuce growth by using light diffusion films under roof-mounted PV modules. The effects of different light conditions (direct but fluctuating and diffused but uniform irradiations) under PV modules on the morphology, yield, and photosynthesis of hydroponically grown lettuce were investigated. Lettuce growth was inhibited, resulting in lower dry weight and relative growth rate (RGR) with longer leaves, under the fluctuating light by roof-mounted PV modules compared to normal greenhouse conditions. On the other hand, the ratio of leaf width to length increased under diffused light conditions and the values were comparable to those in the control in spring, summer, and fall cultivations. Although the net photosynthetic rate of fully expanded leaves of lettuce grown under diffused light was lowest, their dry weight and RGR were comparable to the control in summer and fall cultivations. Diffused light might penetrate into the lower layers of the leaf canopy, thereby increasing the CO 2 fixation of the whole canopy. Our results suggest that the application of light diffusion films is a viable option for improving crop productivity under roof-mounted PV modules.