Project description:Skeletal muscle atrophy is one of the critical issues which elderly people face. The precise mechanism underlying muscle atrophy during aging is not fully understood. In order to identify miRNA whose expression is changed in age-associated muscle atrophy, we performed miRNA expression profiling of skeletal muscles in young and aged rats. Microarray analysis revealed differential miRNA expression in EDL and soleus muscles of aged rats compared with those of young rats. We next investigated whether the age-associated changes of miRNA expression observed in rats were recapitulated in mice and found that the expression level of miR-206 in EDL muscle and that of miR-196a in EDL and soleus muscles were respectively higher and lower in aged rodents than in young rodents. In mouse C2C12 myoblasts and myotubes, introduction of miR-196a decreased the protein level of Forkhead-box transcription factor Foxo1, a known target of miR-196a, indicating that miR-196a may regulate Foxo1 expression also in skeletal muscles. Furthermore, miR-196a overexpression exacerbated cell death caused by an exposure to hydrogen peroxide. Lastly, we demonstrated that expression of Foxo1 was elevated in EDL and soleus muscles of aged mice compared with those of young mice. These results suggest that miRNAs are involved in skeletal muscle atrophy during aging and that decreased miR-196a expression may protect skeletal muscle cells from oxidative stress in part through induction of Foxo1.
Project description:The extraocular muscles (EOM) are anatomically and physiologically distinct from other skeletal muscles. EOM are preferentially affected in mitochondrial myopathies, but spared in Duchenne's muscular dystrophy. The anatomical and pathophysiological properties of EOM have been attributed to their unique molecular makeup: an allotype. We used expression profiling to define molecular features of the EOM allotype. We found 346 differentially expressed genes in rat EOM compared with tibialis anterior, based on a twofold difference cutoff. Genes required for efficient, fatigue-resistant, oxidative metabolism were increased in EOM, whereas genes for glycogen metabolism were decreased. EOM also showed increased expression of genes related to structural components of EOM such as vessels, nerves, mitochondria, and neuromuscular junctions. Additionally, genes related to specialized functional roles of EOM such as the embryonic and EOM-specific myosin heavy chains and genes for muscle growth, development, and/or regeneration were increased. The EOM expression profile was validated using biochemical, structural, and molecular methods. Characterization of the EOM expression profile begins to define gene transcription patterns associated with the unique anatomical, metabolic, and pathophysiological properties of EOM.
Project description:To investigate the metabolic dysfunction in the process of sarcopenia, we collected the skeletal muscles from the participants of healthy aged, pre-sarcopenia and sarcopenia. We then performed gene expression profiling analysis using data obtained from RNA-seq of skeletal muscle tissue from healthy aged, pre-sarccopenia and sarcopenia.
Project description:Few studies have assessed the patterns of parasite populations of rodents over a longitudinal gradient in Chile. In this work, the gastrointestinal helminthic fauna of invasive rodents in Chile was examined to assess the association between their presence/absence and abundance with latitude, host sex, and host body condition, and to assess the coexistence and correlation of the abundance between parasite species. Rodents were obtained from 20 localities between 33 and 43°S. Helminths were extracted from the gastrointestinal tract and identified morphologically. Overall, 13 helminth taxa were obtained. The most frequently identified parasite species was Heterakis spumosa, and the most abundant was Syphacia muris, while Physaloptera sp. was the most widely distributed. No locality presented with a coexistence that was different from that expected by chance, while the abundance of five helminthic species correlated with the abundance of another in at least one locality, most likely due to co-infection rather than interaction. Host sex was associated with parasite presence or abundance, and female sex-biased parasitism was notably observed in all cases. Body condition and latitude presented either a positive or negative association with the presence or abundance of parasites depending on the species. It is notable that the likely native Physaloptera sp. is widely distributed among invasive rodents. Further, gravid females were found, suggesting spillback of this species to the native fauna. The low frequency and abundance of highly zoonotic hymenolepid species suggest that rodents are of low concern regarding gastrointestinal zoonotic helminths.