Glycogen-enzymes containing bodies in type 2 fibres of tenotomized muscles in the rat

Inclusion bodies containing glycogen-enzymes were found in 30 to 60% of type 2 fibres of tenotomized calf muscles (m. gastrocnemius, m. soleus, m. plantaris) in rats, using histochemical reactions. The bodies appeared within 1 week after the tenotomy and were localized both in the central and the subsarcolemmal regions and rarely extruded into the extracellular space. These aggregates are 3 to 15 microns in length and 2 to 11 microns in diameter. In addition to glycogen, these bodies also contained various enzymes of the glycogen metabolism such as phosphorylase, a branching enzyme, and glucose-6-phosphatase, but showed no NADH-reductase, lactate dehydrogenase, or myofibrillar ATP-ase activity. The results indicate that glycogen-enzymes containing bodies are a degenerative phenomenon, which occurs only in type 2 fibres of the tenotomized muscles.     

Selenium as an anti-oxidant and pro-oxidant in ryegrass

Selenium is an essential element for antioxidation reactions in human and animals. In order to study its biological role in higher plants, ryegrass (Lolium perenne) was cultivated in a soil without Se or amended with increasing dosages of H₂SeO₄ (0.1, 1.0, 10.0 and 30.0 mg Se kg⁻¹). Ryegrass was harvested twice and the yields were analyzed for antioxidative systems and growth parameters. Selenium exerted dual effects: At low concentrations it acted as an antioxidant, inhibiting lipid peroxidation, whereas at higher concentrations, it was a pro-oxidant, enhancing the accumulation of lipid peroxidation products. The antioxidative effect was associated with an increase in glutathione peroxidase (GSH-Px) activity, but not with superoxide dismutase (SOD) and αα-tocopherol, which was the only tocopherol detected. In the second yield, the diminished lipid peroxidation due to a proper Se addition coincided with promoted plant growth. The oxidative stress found at the Se addition level ≥ 10 mg kg⁻¹ resulted in drastic yield losses. This result indicates that the toxicity of Se can be attributed, in addition to metabolic disturbances, to its pro-oxidative effects. Neither the growth-promoting nor the toxic effect of Se could be explained by the changes in the total chlorophyll concentration. This revised version was published online in June 2006 with corrections to the Cover Date.     

Macromolecular composition of the sarcolemma and endomysium in the rat

The macromolecular composition of sarcolemma and endomysium was studied by classical staining methods for glycosaminoglycans and using immunological techniques for proteins. Both proteoglycans and glycosaminoglycans (heparan sulphate, dermatan sulphate, chondroitin sulphate) could be detected in the sarcolemma. Type IV and type V collagen and laminin were found exclusively in the sarcolemma and endomysium. Type I and type III collagen as well as fibronectin were detected both in the endomysium and perimysium.     

Effects of Long-Term Nitrogen Addition and Atmospheric Nitrogen Deposition on Carbon Accumulation in Picea sitchensis Plantations

This study aimed to assess the combined effects of long-term nitrogen (N) supply and nitrogen deposition (N _dep) on carbon (C) accumulation within Sitka spruce [Picea sitchensis (Bong.) Carr.] plantations in Scotland. Six study sites established from 1970 to 1982 were periodically N-fertilized, monitored over time and commonly surveyed in 2010. Soil, aboveground biomass, and ground vegetation C stock changes were analyzed; aboveground C stocks were correlated with total additional N experienced at each site, that is, the sum of experimental N supply (N _add) and site-specific accumulated N _dep from 1900 to 2010. Results showed a positive N effect on aboveground tree C stock and no decline in tree growth was observed either during fertilization or after the latest N addition. The amount of C in litter was significantly higher in experimentally N-treated plots, whereas the amount of C in understory vegetation was higher in control plots. Pooling all the compartments (that is, understory vegetation, litter, soil, and tree biomass) the total ecosystem C content was estimated for each site, and at most sites a higher C stock was estimated for N-treated plots. Differences in aboveground C accumulation rates between treated and control plots were lower at sites with high levels of accumulated N _dep. Our results indicate that site-specific accumulated N _dep should be considered to understand tree growth responses to N fertilization.     

Secretome profiling of Propionibacterium freudenreichii reveals highly variable responses even among the closely related strains

This study compared the secretomes (proteins exported out of the cell) of Propionibacterium freudenreichii of different origin to identify plausible adaptation factors. Phylosecretomics indicated strain‐specific variation in secretion of adhesins/invasins (SlpA, InlA), cell‐wall hydrolysing (NlpC60 peptidase, transglycosylase), protective (RpfB) and moonlighting (DnaK, GroEL, GaPDH, IDH, ENO, ClpB) enzymes and/or proteins. Detailed secretome comparison suggested that one of the cereal strains (JS14) released a tip fimbrillin (FimB) in to the extracellular milieu, which was in line with the electron microscopy and genomic analyses, indicating the lack of surface‐associated fimbrial‐like structures, predicting a mutated type‐2 fimbrial gene cluster (fimB‐fimA‐srtC2) and production of anchorless FimB. Instead, the cereal strain produced high amounts of SlpB that tentatively mediated adherent growth on hydrophilic surface and adherence to hydrophobic material. One of the dairy strains (JS22), producing non‐covalently bound surface‐proteins (LspA, ClpB, AraI) and releasing SlpA and InlA into the culture medium, was found to form clumps under physiological conditions. The JS22 strain lacked SlpB and displayed a non‐clumping and biofilm‐forming phenotype only under conditions of increased ionic strength (300 mM NaCl). However, this strain cultured under the same conditions was not adherent to hydrophobic support, which supports the contributory role of SlpB in mediating hydrophobic interactions. Thus, this study reports significant secretome variation in P. freudenreichii and suggests that strain‐specific differences in protein export, modification and protein–protein interactions have been the driving forces behind the adaptation of this bacterial species.     

Determination of thermo-oxidation products of plant sterols

Plant sterols are subjected to oxidation when exposed to air and, especially, when heated at high temperatures. We developed a method to study thermo-oxidation of plant sterols. The method consisted of cold saponification, purification of oxides by solid-phase extraction and gas chromatography analysis. To compensate for losses during the procedure, an internal standard was added before saponification. The method showed good recovery of added cholesterol oxides, separation of plant sterol oxides and reproducibility in detecting thermo-oxidation products of stigmasterol and rapeseed oil. Based on this study, the major products are 7-hydroxy, 5,6-epoxy and 7-keto compounds and oxides are formed faster in bulk stigmasterol than in rapeseed oil.     

Ultrastructure and collagen composition of the myo-fascial junction in rat calf muscles.

The collagen composition and ultrastructural organization of the myo-fascial junction was studied using immunohistochemical techniques and electron microscopy. At the myo-fascial junction, a small amount of type-III collagen was found; however, the major collagen component was the type-I collagen. On the longitudinal sites of muscle cells, there were deep recesses and, within these, finger-like structures containing sarcomeres. In these recesses and in the finger-like structures of the myo-fascial junction, the sarcolemma was thickened (three times) in a similar way to the basal lamina at the myotendinous junction. Thin collagen fibers were closely associated with the thickened sarcolemma of the finger-like structures.     

Morphology and histochemistry of the myotendineal junction of the rat calf muscles. Histochemical, immunohistochemical and electron-microscopic study.

The macromolecular composition and morphometry of the myotendineal junction (MTJ) of slow-twitch (type 1) and fast-twitch (type 2) muscle fibers were studied in gastrocnemius-soleus-Achilles unit of the rat. Proteoglycans and glycosaminoglycans, type III collagen, fibronectin and laminin could be detected at the myotendineal junction. Due to the membrane folding finger-like processes were seen at the MTJ. The processes of type 1 fibers were greater in size. However, due to the subdivisions the processes of type 2 muscle fibers had a significantly greater surface length per muscle cell diameter than type 1 fibers. The myotendineal endings of both fiber types had a characteristic basal lamina, which was about three times thicker than in the longitudinal site of the same muscle cells. The basal lamina of type 1 fibers at the MTJ was significantly thicker than that of type 2 fibers.     

Plant stanols induce intestinal tumor formation by up-regulating Wnt and EGFR signaling in ApcMin mice

The rate of APC mutations in the intestine increases in middle-age. At the same period of life, plant sterol and stanol enriched functional foods are introduced to diet to lower blood cholesterol. This study examined the effect of plant stanol enriched diet on intestinal adenoma formation in the Apc^Min mouse. Apc^Min mice were fed 0.8% plant stanol diet or control diet for nine weeks. Cholesterol, plant sterols and plant stanols were analyzed from the caecum content and the intestinal mucosa. Levels of β-catenin, cyclin D1, epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase 1/2 (ERK1/2) were measured from the intestinal mucosa by Western blotting. Gene expression was determined from the intestinal mucosa using Affymetrix and the data were analyzed for enriched categories and pathways. Plant stanols induced adenoma formation in the small intestine, however, the adenoma size was not affected. We saw increased levels of nuclear β-catenin, phosphorylated β-catenin (Ser675 and Ser552), nuclear cyclin D1, total and phosphorylated EGFR and phosphorylated ERK1/2 in the intestinal mucosa after plant stanol feeding. The Affymetrix data demonstrate that several enzymes of cholesterol synthesis pathway were up-regulated, although the cholesterol level in the intestinal mucosa was not altered. We show that plant stanols induce adenoma formation by activating Wnt and EGFR signaling. EGFR signaling seems to have promoted β-catenin phosphorylation and its translocation into the nucleus, where the expression of cyclin D1 was increased. Up-regulated cholesterol synthesis may partly explain the increased EGFR signaling in the plant stanol-fed mice.     

Free mobilization and low- to high-intensity exercise in immobilization-induced muscle atrophy

After 3 wk of immobilization, the effects offree cage activity and low- and high-intensity treadmill running (8 wk)on the morphology and histochemistry of the soleus and gastrocnemius muscles in male Sprague-Dawley rats were investigated. In both muscles,immobilization produced a significant(P < 0.001) increase in the meanpercent area of intramuscular connective tissue (soleus: 18.9% inimmobilized left hindlimb vs. 3.6% in nonimmobilized right hindlimb)and in the relative number of muscle fibers with pathologicalalterations (soleus: 66% in immobilized hindlimb vs. 6% in control),with a simultaneous significant (P < 0.001) decrease in the intramuscular capillary density (soleus: mean capillary density in the immobilized hindlimb only 63% of that in thenonimmobilized hindlimb) and muscle fiber size (soleus type I fibers:mean fiber size in the immobilized hindlimb only 69% of that in thenonimmobilized hindlimb). Many of these changes could not be correctedby free remobilization, whereas low- and high-intensity treadmillrunning clearly restored the changes toward control levels, the effectbeing most complete in the high-intensity running group. Collectively,these findings indicate that immobilization-induced pathologicalstructural and histochemical alterations in rat calf muscles are, to agreat extent, reversible phenomena if remobilization is intensified byphysical training. In this respect, high-intensity exercise seems morebeneficial than low-intensity exercise.