Mechanogenetic role of actomyosin complex in branching morphogenesis of epithelial organs

The actomyosin complex plays crucial roles in various life processes by balancing the forces generated by cellular components. In addition to its physical function, the actomyosin complex participates in mechanotransduction. However, the exact role of actomyosin contractility in force transmission and the related transcriptional changes during morphogenesis are not fully understood. Here, we report a mechanogenetic role of the actomyosin complex in branching morphogenesis using an organotypic culture system of mouse embryonic submandibular glands. We dissected the physical factors arranged by characteristic actin structures in developing epithelial buds and identified the spatial distribution of forces that is essential for buckling mechanism to promote the branching process. Moreover, the critical genes required for the distribution of epithelial progenitor cells were regulated by YAP/TAZ through a mechanotransduction process in epithelial organs. These findings are important for our understanding of the physical processes involved in the development of epithelial organs and provide a theoretical background for developing new approaches for organ regeneration.

Biochemical and morphological changes in muscular tissue of pond fish in the process of autolytic transformations

Physical and chemical processes in muscular tissue of pond fish are considered in the process of storage. The muscle contraction appears mainly because of the myofibrils activity that utilizes energy of the sarcoplasm substances. Intense disintegration of glycogen causes sharp acidification (pH decreasing) in the muscular tissue that affects on chemical composition and physical-colloidal structure of proteins. Hardening of the muscular tissue is observed in the first hours of storage because of the proteins transformation to actin and myosin in insoluble actomyosin complex. The highest level of actomyosin is observed in the first 3–5 hours that is the evidence of unstable rate of biochemical processes corresponded to changing activity of enzyme systems. Cumulative level of the actomyosin complex grows in the first 8 hours of storage for all investigated fish species. Organoleptic and technological characteristics of the fish meat improve significantly in the process of its maturation: the meat has no definite taste and smell in early stages of autolysis, but these properties appear in 3–4 days, depending on the storage temperature, due to enzymatic decomposition of proteins, peptides, nucleotides, carbohydrates, lipids, etc. Recommendations on storage are presented for certain groups of fish products in dependence on initial properties of raw materials.