Recent advances in muscle research

Behavioral correlates of fascicular organization: The confluence of muscle architectural anatomy and function

Muscle is a complex tissue that has been studied on numerous hierarchical levels: from gross descriptions of muscle organization to cellular analyses of fiber profiles. In the middle of this space between organismal and cellular biology lies muscle architecture, the level at which functional correlations between a muscle's internal fiber organization and contractile abilities are explored. In this review, we summarize this relationship, detail recent advances in our understanding of this form-function paradigm, and highlight the role played by The Anatomical Record in advancing our understanding of functional morphology within muscle over the past two decades. In so doing, we honor the legacy of Editor-in-Chief Kurt Albertine, whose stewardship of the journal from 2006 through 2020 oversaw the flourishing of myological research, including numerous special issues dedicated to exploring the behavioral correlates of myology across diverse taxa. This legacy has seen the The Anatomical Record establish itself as a preeminent source of myological research, and a true leader within the field of comparative anatomy and functional morphology.

Identification and expression profile of microRNA in seven tissues of the Golden snub-nosed monkey (Rhinopithecus roxellanae)

MicroRNAs (miRNAs) are key in the post-transcriptional regulation of gene expression and thus characterization of miRNAs and investigation of the relative abundance and specificity of tissue expression are essential for understanding gene expression in the golden snub-nosed monkey (GSM, Rhinopithecus roxellanae). Here, we report the first dataset of GSM miRNAs where we identified 460 miRNAs in seven tissues, with 246 conserved known mature miRNAs and 214 novel mature miRNAs. We determined miRNA abundance and expression in the seven tissues using a Tissue Specificity Index score and found that most novel GSM miRNAs showed a highly tissue-specific expression pattern. In particular, 67 novel miRNAs and the miR-34 family were expressed in abundance only in the lung. Five known miRNAs were highly abundant in digestive organs such as the pancreas and liver, and four novel miRNAs were highly expressed in the heart and muscle. Annotation of target genes of GSM miRNAs indicated that target genes were enriched in many important pathways, such as the HIF-1 signaling pathway and xenobiotic biodegradation-related pathways. Collectively, these results emphasize that miRNAs play important roles in GSM diet and high-elevation adaptation regulation. In summary, this study provides essential information on GSM miRNAs and will benefit further investigations of the function and mechanism of miRNAs in controlling gene expression in the GSM.

Exercise and Muscle Atrophy

The incidence of muscle atrophy is increasing with each passing year, which imposes a huge burden on the quality of life of patients. It is a public health issue that causes a growing concern around the world. Exercise is one of the key strategies to prevent and treat various diseases. Appropriate exercise is conducive to compensatory muscle hypertrophy, to improve muscle strength and elasticity, and to train muscle coordination, which is also beneficial to the recovery of skeletal muscle function and the regeneration of muscle cells. Sequelae of paralysis of patients with limb dyskinesia caused by muscle atrophy will be significantly alleviated after regular exercise therapy. Furthermore, exercise therapy can slow down or even reverse muscle atrophy. This article aims to introduce the characteristics of muscle atrophy and summarize the role and mechanism of exercise in the treatment of muscle atrophy in the existing studies, in order to further explore the mechanism of exercise to protect muscle atrophy and provide protection for patients with muscular atrophy.

Assembly and Maintenance of Myofibrils in Striated Muscle

In this chapter, we present the current knowledge on de novo assembly, growth, and dynamics of striated myofibrils, the functional architectural elements developed in skeletal and cardiac muscle. The data were obtained in studies of myofibrils formed in cultures of mouse skeletal and quail myotubes, in the somites of living zebrafish embryos, and in mouse neonatal and quail embryonic cardiac cells. The comparative view obtained revealed that the assembly of striated myofibrils is a three-step process progressing from premyofibrils to nascent myofibrils to mature myofibrils. This process is specified by the addition of new structural proteins, the arrangement of myofibrillar components like actin and myosin filaments with their companions into so-called sarcomeres, and in their precise alignment. Accompanying the formation of mature myofibrils is a decrease in the dynamic behavior of the assembling proteins. Proteins are most dynamic in the premyofibrils during the early phase and least dynamic in mature myofibrils in the final stage of myofibrillogenesis. This is probably due to increased interactions between proteins during the maturation process. The dynamic properties of myofibrillar proteins provide a mechanism for the exchange of older proteins or a change in isoforms to take place without disassembling the structural integrity needed for myofibril function. An important aspect of myofibril assembly is the role of actin-nucleating proteins in the formation, maintenance, and sarcomeric arrangement of the myofibrillar actin filaments. This is a very active field of research. We also report on several actin mutations that result in human muscle diseases.