No abstract

Duchenne muscular dystrophy (DMD) is a fatal X-linked muscle-wasting disease caused by mutations of the gene encoding the cytoskeletal protein dystrophin. Therapeutic options for DMD are limited because the pathogenetic mechanism by which dystrophin deficiency produces the clinical phenotype remains obscure. Recent reports of abnormal alpha-adrenergic vasoregulation in the exercising muscles of DMD patients and in the mdx mouse, an animal model of DMD, prompted us to hypothesize that the dystrophin-deficient smooth muscle contributes to the vascular and dystrophic phenotypes of DMD. To test this, we generated transgenic mdx mice that express dystrophin only in smooth muscle (SMTg/mdx). We found that alpha-adrenergic vasoconstriction was markedly attenuated in the contracting hindlimbs of C57BL/10 wild-type mice, an effect that was mediated by nitric oxide (NO) and was severely impaired in the mdx mice. SMTg/mdx mice showed an intermediate phenotype, with partial restoration of the NO-dependent modulation of alpha-adrenergic vasoconstriction in active muscle. In addition, the elevated serum creatine kinase levels observed in mdx mice were significantly reduced in SMTg/mdx mice. This is the first report of a functional role of dystrophin in vascular smooth muscle.

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The effects of 15 N-labelled green manure (GM) application on rice yield and N uptake were investigated and compared with those of inorganic fertilizer (IF) and no fertilizer (NF) application. Nine GMs (white clover, Chinese milk vetch, hairy vetch, crimson clover, oats, rye, Italian ryegrass, white mustard, lacy phacelia) were either incorporated into or surface-applied on paddy soil. Among the nine GM treatments, the rice yield and N uptake tended to be higher in the white clover and hairy vetch treatments. The rice N uptake efficiency from the applied N source was highest in the incorporated hairy vetch (56%), followed by IF (52%), and incorporated white clover (44%), whereas for the other treatments there were no significant differences. The mineral fertilizer equivalent values of hairy vetch and white clover in case of the incorporation were 108% and 84%, respectively. Therefore, hairy vetch and white clover seem to be the most efficient organic N source as alternatives to inorganic N fertilizers. The N uptake efficiency of rice and residual N in soil derived from GM were higher in the incorporation treatments than that in the surface-applied treatments, indicating that N losses from the soil-plant system were lower with the incorporation.

One of the ways to reduce chemical fertilizer application is the use of cover crops, which improve soil properties and supply nutrition to subsequent crops. The application effect of a legume cover crop, hairy vetch (Vicia villosa R., HV), on N dynamics in fresh market tomatoes (Solanum lycopersicum L.), 'House Momotaro,' was investigated using the 15 N-labeling method. Tomato seedlings were transplanted into a 1/2000 a Wagner pot at 0, 80, and 240 kg·ha −1 of N application (N0HV, N80HV, and N240HV) on June 9, 2011. Before transplanting, the labeled HV and chemical fertilizers were incorporated into the soil. Five tomato plants were collected 6 times in each treatment and then separated into leaves, stems, and roots. Fruits were harvested at maturity. HV-derived N uptake was recognized mainly in the first 4 weeks after transplant (WAT). Especially in N240HV, HV-derived N uptake ceased at 4 WAT. The uptake amounts of HV-derived N at 10 WAT were 587, 657, and 729 mg·plant −1 in N240HV, N80HV, and N0HV, respectively, and were increased by decreasing N fertilizer application. The rate of N uptake derived from HV to total N uptake in tomato plants (%N dfhv ) was the highest at 2 WAT, and %N dfhv in N80HV (52.1%) and N0HV (51.5%) were significantly higher than in N240HV (43.6%). After 2 WAT, %N dfhv decreased gradually in all N rates as tomatoes grew and decreased to 24.8%, 34.4%, and 37.1% in N240HV, N80HV, and N0HV, respectively, until 12 WAT. Nitrogen use efficiency (NUE) from HV-derived N was the highest at 10 WAT, and N0HV (55.3%) was significantly higher than N240HV (44.5%) and N80HV (49.8%). The partition rate of HVderived N into fruits was 63.9%, and 39.7% of HV-derived N was distributed into 1st and 2nd fruit clusters. From these results, it was clarified that HV can be expected to be an alternative N fertilizer because HV-derived N was absorbed effectively with a small amount of N fertilizer. Further research on fertilizer management in tomato's early stage will be needed for an N-reduction system because HV-derived N was mainly absorbed for 4 WAT.