Characterization of a gene cluster for exopolysaccharide biosynthesis and virulence in Erwinia stewartii.

We have previously cloned the genes for synthesis of capsular polysaccharide (cps) and slime from Erwinia stewartii in cosmid pES2144. In this study, pES2144 was shown to complement 14 spontaneous cps mutants. These mutants were characterized by probing Southern blots of mutant genomic DNA with pES2144; insertions were detected in four mutants and deletions in six mutants. Genetic and physical maps of the pES2144 cps region were constructed by subcloning, restriction analysis, and transposon mutagenesis with Tn5, Tn5lac, and Tn3HoHo1. Mutations affecting the ability of pES2144 to restore mucoidy to cps deletion mutants were located in five regions, designated cpsA to cpsE. None of the cps mutants were able to cause systemic wilting of corn plants, and mutations in cps regions B to E further abolished the ability of the bacterium to cause watersoaked lesions on seedlings. The gene for uridine-5'-diphosphogalactose 4-epimerase (galE) was linked to the cps genes on pES2144. In E. stewartii, galE was constitutively expressed, whereas the genes for galactokinase (galK) and galactose-1-phosphate uridyltransferase (galT) were inducible and not linked to galE. Thus, galE does not appear to be part of the gal operon in this species

Skeletal muscle response to endurance training in IL-6^{-/-} mice

We examined effects of moderate-intensity endurance training on muscle COX/CS activities and V’O2max in control WT and IL-6−/− mice. Animals were exercised for 10 weeks on treadmill for 1 h, 5 days a week at velocity of 6 m·min−1 which was increased by 0.5 m·min−1 every 2 weeks up to 8 m·min−1 . Training triggered an increase of enzyme activities in soleus muscle of WT mice (COX: 480.3±8.9 U·g−1 in sedentary group vs. 773.3±62.6 U·g−1 in trained group, P<0.05 and CS: 374.0±6.0 U·g−1 in sedentary group vs. 534.2±20.5 U·g−1 in trained group, P<0.01, respectively) whereas no changes were observed in soleus of IL6−/− mice. Moreover, in mixed gastrocnemius muscle of trained IL-6−/− mice enzyme activities tended to be lower (COX: 410.7±48.4 U·g−1 for sedentary vs. 277.0±36.5 U·g−1 for trained group and CS: 343.8±24.6 U·g−1 for sedentary vs. 251.7±27.1 U·g−1 for trained group). No changes in V’O2max were observed in WT and IL-6−/− mice after training. Concluding, moderate-velocity endurance training-induced increase in COX and CS activities in muscles of WT mice only which suggests that IL-6 regulates training-induced skeletal muscle responses to exercise. Copyright © 2015, Georg Thieme Verlag KG. All rights reserved

Exercise training in Tg\u3b1q*44 mice during the progression of chronic heart failure: cardiac vs. peripheral (soleus muscle) impairments to oxidative metabolism

Cardiac function, skeletal (soleus) muscle oxidative metabolism, and the effects of exercise training were evaluated in a transgenic murine model (Tg\u3b1q*44) of chronic heart failure during the critical period between the occurrence of an impairment of cardiac function and the stage at which overt cardiac failure ensues (i.e., from 10 to 12 mo of age). Forty-eight Tg\u3b1q*44 mice and 43 wild-type FVB controls were randomly assigned to control groups and to groups undergoing 2 mo of intense exercise training (spontaneous running on an instrumented wheel). In mice evaluated at the beginning and at the end of training we determined: exercise performance (mean distance covered daily on the wheel); cardiac function in vivo (by magnetic resonance imaging); soleus mitochondrial respiration ex vivo (by high-resolution respirometry); muscle phenotype [myosin heavy chain (MHC) isoform content; citrate synthase (CS) activity]; and variables related to the energy status of muscle fibers [ratio of phosphorylated 5'-AMP-activated protein kinase (AMPK) to unphosphorylated AMPK] and mitochondrial biogenesis and function [peroxisome proliferative-activated receptor-\u3b3 coactivator-\u3b1 (PGC-1\u3b1)]. In the untrained Tg\u3b1q*44 mice functional impairments of exercise performance, cardiac function, and soleus muscle mitochondrial respiration were observed. The impairment of mitochondrial respiration was related to the function of complex I of the respiratory chain, and it was not associated with differences in CS activity, MHC isoforms, p-AMPK/AMPK, and PGC-1\u3b1 levels. Exercise training improved exercise performance and cardiac function, but it did not affect mitochondrial respiration, even in the presence of an increased percentage of type 1 MHC isoforms. Factors "upstream" of mitochondria were likely mainly responsible for the improved exercise performance.NEW & NOTEWORTHY Functional impairments in exercise performance, cardiac function, and soleus muscle mitochondrial respiration were observed in transgenic chronic heart failure mice, evaluated in the critical period between the occurrence of an impairment of cardiac function and the terminal stage of the disease. Exercise training improved exercise performance and cardiac function, but it did not affect the impaired mitochondrial respiration. Factors "upstream" of mitochondria, including an enhanced cardiovascular O2 delivery, were mainly responsible for the functional improvement

Voluntary physical activity counteracts Chronic Heart Failure progression affecting both cardiac function and skeletal muscle in the transgenic Tgαq*44 mouse model

Physical activity is emerging as an alternative nonpharmaceutical strategy to prevent and treat a variety of cardiovascular diseases due to its cardiac and skeletal muscle beneficial effects. Oxidative stress occurs in skeletal muscle of chronic heart failure (CHF) patients with possible impact on muscle function decline. We determined the effect of voluntary-free wheel running (VFWR) in preventing protein damage in Tgαq*44 transgenic mice (Tg) characterized by a delayed CHF progression. In the early (6 months) and transition (12 months) phase of CHF, VFWR increased the daily mean distance covered by Tg mice eliminating the difference between Tg and WT present before exercise at 12 months of age (WT Pre-EX 3.62 ± 1.66 vs. Tg Pre-EX 1.51 ± 1.09 km, P 0.005). This effect was concomitant with an improvement of in vivo cardiac performance [(Cardiac Index (mL/min/cm2 ): 6 months, untrained-Tg 0.167 ± 0.005 vs. trained-Tg 0.21 ± 0.003, P 0.05). Prolonged voluntary physical activity performed before the onset of CHF end-stage, appears to be a useful tool to increase cardiac function and to reduce skeletal muscle oxidative damage counteracting physical activity decline