Polarization of Myosin II Refines Tissue Material Properties to Buffer Mechanical Stress

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Matrix-embedded cells control osteoclast formation

Osteoclasts resorb the mineralized matrices formed by chondrocytes or osteoblasts. The cytokine receptor activator of nuclear factor-κB ligand (RANKL) is essential for osteoclast formation and thought to be supplied by osteoblasts or their precursors, thereby linking bone formation to resorption. However, RANKL is expressed by a variety of cell types, and it is unclear which of them are essential sources for osteoclast formation. Here we have used a mouse strain in which RANKL can be conditionally deleted and a series of Cre-deleter strains to demonstrate that hypertrophic chondrocytes and osteocytes, both of which are embedded in matrix, are essential sources of the RANKL that controls mineralized cartilage resorption and bone remodeling, respectively. Moreover, osteocyte RANKL is responsible for the bone loss associated with unloading. Contrary to the current paradigm, RANKL produced by osteoblasts or their progenitors does not contribute to adult bone remodeling. These results suggest that the rate-limiting step of matrix resorption is controlled by cells embedded within the matrix itself.     

An in vivo and in vitro comparison of the effects of amoxicillin,gentamicin, and cefazolin sodium antibiotics on the mouse hepatic and renal glutathione reductase enzyme

Despite the fact that the use of antibiotics is increasing worldwide, it is clear that antibiotics can lead to oxidative stress. This is the first study to make a comparison of the impact of frequently prescribed antibiotics, including amoxicillin, gentamicin, and cefazolin sodium, on the gene, protein, and activity of glutathione reductase (GR), which is one of the primary antioxidant enzymes, in mouse liver and kidney tissues. First, the GR enzyme was purified by the 2′,5′‐ADP Sepharose 4B affinity chromatography with a specific activity of 84.615 EU/mg protein and 9.63 EU/mg protein from the mouse liver and kidney, respectively. The in vitro inhibitory effects of the antibiotics in question was determined. While cefazolin sodium did not exhibit any inhibitory effect, gentamicin and amoxicillin inhibited GR activity in both tissues. Furthermore, the in vivo effects of these drugs were investigated, and amoxicillin and cefazolin sodium‐inhibited GR activity in both liver and kidney tissues, while gentamicin did not have any effect on the kidney. Besides, while gentamicin downregulated and cefazolin sodium upregulated Gr gene expression, amoxicillin did not alter it. Protein expression was only affected by the administration of cefazolin sodium in the kidney. This study is important as it demonstrates that while amoxicillin and gentamicin showed parallel effects on the GR activity in liver and kidney tissues both in vitro and in vivo, cefazolin sodium had a very strong effect on hepatic and renal GR in vivo. Furthermore, the antibiotics used in this study induced oxidative stress in both tissues.     

Localization of pan-cadherin immunoreactivity in adult rat tissues

Cadherins, being responsible for selective cell recognition and normal tissue integrity in adults, regulate morphogenesis in a variety of organs during development. In this study, anti-rat pan-cadherin antibody, specific to all subgroups of the cadherin family, was used to map the distribution of the pan-cadherin immunoreactivity in adult rat organs. Pan-cadherin immunoreactivity positive tissues were: secretory cells of the adenohypophysis, autonomic nerve, corneal epithelium, oesophageal nerve plexus, stomach and pyloric glandular cells, epithelium of the ileum and its nerve plexus, alveolar cells of the lung, proximal convoluted tubules of the kidney, islet cells of Langerhans, and the acinar cells of the exocrine pancreas. For the first time, positive pan-cadherin immunoreactivity was demonstrated in the epithelial cells of the corpus ciliaris and in the nerve plexus of corpus cavernosum of the penis. In conclusion, our results suggest that cells in many tissues and organs of the adult rat synthesize cadherins.     

Subgenomic analysis of microRNAs in polyploid wheat

In this study, a survey of miRNAs using the next-generation sequencing data was performed at subgenomic level. After analyzing shotgun sequences from chromosome 4A of bread wheat (Triticum aestivum L.), a total of 68 different miRNAs were predicted in silico, of which 37 were identified in wheat for the first time. The long arm of the chromosome was found to harbor a higher variety (51) and representation (3,928) of miRNAs compared with the short arm (49; 2,226). Out of the 68 miRNAs, 32 were detected to be common to both arms, revealing the presence of separate miRNA clusters in the two chromosome arms. The differences in degree of representation of the different miRNAs were found to be highly variable, ranging 592-fold, which may have an effect on target regulation. Targets were retrieved for 62 (out of 68) of wheat-specific, newly identified miRNAs indicated that fundamental aspects of plant morphology such as height and flowering were predicted to be affected. In silico expression blast analysis indicated 24 (out of 68) were found to give hits to expressed sequences. This is the first report of species- and chromosome-specific miRNAs.