The mechanism of skeletal muscle atrophy : finding from space experiment

Skeletal muscle atrophy is a response to decreased physical signals (unloading), such as under microgravity, bed rest and neural inactivation, and is characterized by muscle volume loss and muscle fiber-type switching. We previously demonstrated that elevated ubiquitin ligase casitas B-lineage lymphoma-b (Cbl-b) resulted in the loss of muscle volume. Here, we showed that the ROS-mediated signal transduction caused by microgravity or its simulation contributes to Cbl-b expression. In L6 myotubes, the assessment of redox status revealed that oxidized glutathione was increased under microgravity conditions, and simulated microgravity caused a burst of ROS, implicating ROS as a critical upstream mediator linking to downstream atrophic signaling. ROS generation activated the ERK 1/2 early-growth response protein (Egr) 1/2-Cbl-b signaling pathway. Our results suggest that under microgravity conditions, elevated ROS may be a crucial mechanotransducer in skeletal muscle cells, regulating muscle mass through Cbl-b expression activated by the ERK-Egr signaling pathway

Characterization of soil microflora on a successional glacier foreland in the high Arctic on Ellesmere Island, Nunavut, Canada using phospholipid fatty acid analysis

We investigated soil microbial biomass and community structure along a primary successional gradient after deglaciation in the high Arctic, at Ellesmere Island, Nunavut, Canada(80°50\u27N, 82°45\u27W). Soil samples were collected from five glacial moraines(M1 to M5) with different developmental periods. Time since the recession of glaciers at M1, M3, and M5 was estimated to be 300, 9000, and over 17000 years, respectively. Soil samples from five points in each moraine were subjected to phospholipid fatty acid(PLFA) analysis. Total PLFA content(an index of microbial biomass) in M1 was significantly lower than those in older moraines(M2-M5), whereas the content remained at an almost constant level from M2 to M5. Significant differences in PLFA composition(an index of microbial community structure) were also observed between M1 and older moraines(M2-M5); the proportion of straight chain saturated fatty acids in M1 was higher than those in older moraines(M2-M5), whereas those of branched fatty acids and unsaturated fatty acids in M1 were lower than those in older moraines(M2-M5). These results suggest that changes of microflora occurred in the early phase of succession after deglaciation and became stable thereafter. Microbial biomass had a positive correlation with soil carbon and nitrogen contents over the successional chronosequence, suggesting that development of soil microflora was affected in part by organic matter accumulation

Relationships between vegetation types and soil properties along a topographical gradient on the northern coast of the Brgger Peninsula, Svalbard

Vegetation patterns in the high Arctic vary not only with proglacial chronosequence but also with a topographical gradient on older deglaciated areas which are covered by mature vegetation. A preliminary survey of local scale vegetation patterns along a topographical gradient with special reference to soil properties was conducted on the northern coast of the Brgger Peninsula, Svalbard in the high Arctic. Three community types of vascular plants were distinguished by common dominants: Cardamine type, Salix type and Oxyria/Luzula type. Each community type was comprised of different habitat types. The Cardamine type was restricted to near the bottom of depressions, where there was high soil water content. The Oxyria/Luzula type was characterized by habitats belonging to upper slopes to ridges, having high gravel content soils. On the other hand, the habitat preference of the Salix type, which had higher vegetation cover and biomass of vascular plants compared to the other two types, was not clear. The core habitat of fertile/undisturbed area, as described by the centrifugal community organization model, might be dominated by Salix polaris in this area. The other species had a refugium from interspecific competition in their preferred peripheral habitats such as exposed ridge or wetland

Decomposition and ergosterol content of the moss Hylocomium splendens litter under various climatic conditions

We examined the differences in the decomposition rate and fungal biomass in the litter of Hylocomium splendens among forests under different climatic conditions. The samples were collected from one boreal forest in Canada, three subalpine forests on Mt. Fuji and one cool temperate forest on Mt. Tsurugi, Shikoku in Japan. The decomposition rate in the cool temperate forest was much faster than those in the boreal and subalpine forests. Ergosterol, which is a component of fungal cell membranes, was used as an indicator of fungal biomass. Ergosterol was detected not only from brown moss litter but also from green shoots of the moss. In spite of the faster decomposition rate, ergosterol content of the moss litter of the cool temperate forest was about one half of those of the boreal and subalpine forests. The results suggest that the relationship between fungal biomass and decomposition rate differs significantly among forest types

Vegetation development and carbon storage on a glacier foreland in the High Arctic, Ny-Ålesund, Svalbard

AbstractThe distribution of organic carbon and its relationship to vegetation development were examined on a glacier foreland near Ny-Ålesund, Svalbard (79°N). In a 0.72-km2 area, we established 43 study plots on three line transects along primary succession from recently deglaciated area to old well-vegetated area. At each plot, we measured the type and percent coverage of vegetation types. The organic carbon content of vegetation, organic soil, and mineral soil samples was determined based on their organic carbon concentration and bulk density. Cluster analysis based on vegetation coverage revealed five types of ground surfaces representing variations in the amounts and allocation patterns of organic carbon. In the later stages of succession, 7%–24% and 31%–40% of organic carbon was contained in the organic and deeper soil layers, respectively. Organic carbon storage in the later stages of succession ranged from 1.1 – 7.9 kg C m−2. A larger amount of organic carbon, including ancient carbon in a raised beach deposit, was expected to be contained in much deeper soil layers. These results suggest that both vegetation development and geological history affect ecosystem carbon storage and that a non-negligible amount of organic carbon is distributed in this High Arctic glacier foreland

Transcriptome Analyses of In Vitro Exercise Models by Clenbuterol Supplementation or Electrical Pulse Stimulation

Exercise has beneficial effects on human health and is affected by two different pathways; motoneuron and endocrine. For the advancement of exercise research, in vitro exercise models are essential. We established two in vitro exercise models using C2C12 myotubes; EPS (electrical pulse stimulation) for a motoneuron model and clenbuterol, a specific β2 adrenergic receptor agonist, treatment for an endocrine model. For clenbuterol treatment, we found that Ppargc1a was induced only in low glucose media (1 mg/mL) using a 1-h treatment of 30 ng/mL clenbuterol. Global transcriptional changes of clenbuterol treatment were analyzed by RNA-seq and gene ontology analyses and indicated that mitogenesis and the PI3K-Akt pathway were enhanced, which is consistent with the effects of exercise. Cxcl1 and Cxcl5 were identified as candidate myokines induced by adrenaline. As for the EPS model, we compared 1 Hz of 1-pulse EPS and 1 Hz of 10-pulse EPS for 24 h and determined Myh gene expressions. Ten-pulse EPS induced higher Myh2 and Myh7 expression. Global transcriptional changes of 10-pulse EPS were also analyzed using RNA-seq, and gene ontology analyses indicated that CaMK signaling and hypertrophy pathways were enhanced, which is also consistent with the effects of exercise. In this paper, we provided two transcriptome results of in vitro exercise models and these databases will contribute to advances in exercise research

Novel magnetic resonance imaging evaluation for valgus instability of the knee caused by medial collateral ligament injury

Instability of the knee after the medial collateral ligament (MCL) injury is usually assessed with the manual valgus stress test, even though, in recent years, it has become possible to apply magnetic resonance imaging (MRI) to the assessment of the damage of the ligament. The valgus instability of 24 patients (12 isolated injuries and 12 multiple ligament injuries) who suffered MCL injury between 1993 and 1998 was evaluated with the Hughston and Eilers classification, which involves radiographic assessment under manual valgus stress to the injured knees. We developed a novel system for classifying the degree of injury to the MCL by calculating the percentage of injured area based on MRI and investigated the relationship between this novel MRI classification and the magnitude of valgus instability by the Hughston and Eilers classification. There was a significant correlation between the 2 classifications (p=0.0006). On the other hand, the results using other MRI based classification systems, such as the Mink and Deutsch classificaiton and the Petermann classification, were not correlated with the findings by the Hughston and Eilers classification in these cases (p0.05). Since MRI is capable of assessing the injured ligament in clinical practice, this novel classification system would be useful for evaluating the stability of the knee and choosing an appropriate treatment following MCL injury.</p

In vitro assessment of six aspiration catheters using a distal protection filter

Background: We assessed performance of 6 aspiration catheters for distal embolization using a distal protection filter in an in vitro experiment. In acute myocardial infarction, a distal protection filter is used for lesions likely to induce a distal embolism. Which aspiration cathether is most effective when used with a distal protection filter remains still unclear.Methods: A 0.5-cm3 bolus of gelatin as a model of stagnant pools of coronary plaque debris was captured in the distal protection filter and aspirated by 6 aspiration catheters. We measured and compared the length of the suspended embolus matter.Results: Among the 6 catheters evaluated, the use of the Export Advance catheter (Medtronic) resulted in significantly shorter lengths of the suspended embolus matter compared to the use of the TVAC II (Nipro), Thrombuster III SL (Kaneka), and Rebirth Pro (Goodman) catheters (p &lt; 0.01). The residual embolus matter in all cases had drained distally to the distal protection filter when the filter was retrieved.Conclusions: The use of the Export Advance catheter showed better performance using a distal protection filter in this in vitro experiment, and its use might be more effective in preventing distal embolisms in combination with a distal protection filter