Objective In order to further study the role of gap junction(GJ) in growth control; and explore the possible mechanisms for the inhibition of GJ formation. Method A monoclonal antibody,called ND6, which is specific for MIP(major intrinsic protein)in the plasma membrane of eye lens fiber cells in chicken,was injected into the right eyes of chicken embryos at development stage 20, while the left eyes were not injected and served as controls. The size of the lenses was measured 24 hours after the ND6 treatment; the protein phosphorylation of the lenses, including intact and homogenized lenses was also analyzed 24 hours after the ND6 treatment. Results The size of the lenses from treated eyes was significantly larger than those of the control ones( P

0.05).Microscopic morphology has also been observed, no visible damage could be found in the structure of lenses from eyes injected with ouabain (figs 3 and 4). Serial sections of paraffin-embedded lenses show that the number of fiber cells increased significantly in experimental samples treated with ouabain at a concentration of 0.1 ?M(table 4, P

OBJECTIVEThis study investigated the role and mechanism of calcineurin (CaN)-nuclear factor of activated T cells (NFAT) pathway in the myoblast apoptosis induced by cyclic tensile strain.

METHODSMyoblasts were cultured using an in vitro-mechanical stimulation model and imposed with tension for different hours with a multi-channel cell stress loading system. Cyclosporine (CsA) was used as CaN inhibitor to clarify the role of CaN in the apoptosis induced by cyclic stress. Hochest 33258 staining and flow cytometry detection were performed to detect the apoptotic cells. Real-time polymerase chain reaction was conducted to detect the mRNA expression of CaN and NFAT. Protein levels of NFAT3 were evaluated by Western blot.

RESULTSThe apoptosis rate increased with the extension of loading time. The mRNA expression of the CaN subunits, CnA and CnB, and the protein levels of NFAT3 also increased. When the myoblasts were incubated with CsA, the apoptosis rate decreased, the mRNA expression of CnA and NFAT3 significantly decreased, and the NFAT3 protein expression levels became significantly lower than those of the groups without CsA.

CONCLUSIONContinuous cyclic tensile stress can induce myoblast apoptosis. The CaN-NFAT signaling pathway may be involved in the cyclic stretch-induced apoptosis of myoblasts.

Apoptosis ; Calcineurin ; genetics ; Cyclosporine ; Flow Cytometry ; Myoblasts ; physiology ; NFATC Transcription Factors ; metabolism ; Real-Time Polymerase Chain Reaction ; Signal Transduction ; T-Lymphocytes

BACKGROUND:Endoplasmic reticulum stress participates in the occurrence and development of many diseases, such as atherosclerosis, diabetes, and Alzheimer’s disease. GRP78 is a marker of endoplasmic reticulum stress. The expression of GRP78 reflects the degree of endoplasmic reticulum stress.
OBJECTIVE:To investigate the effect of cyclic stretch on GRP78 expression of L6 rat myoblasts, and to identify the relationship between cyclic stretch and endoplasmic reticulum stress.
METHODS:In vitro culture-tensile stimulation models of myoblasts of L6 rats were established successful y. The expression of GRP78 of myoblasts exposed to cyclic stretch was determined by reverse transcription-PCR and western blot assay. Stretch groups were subjected to 15%surface elongation at a frequency of 10 cycles per minute, over a period of 1, 6, 12 and 24 hours. cells were simultaneously seeded on a plate in the control and experimental groups with no stimulation.
RESULTS AND CONCLUSION:The expression of GRP78 mRNA was continuously elevated over time after stretched treatment, and significant differences were detected as compared with the control group (P<0.05). GRP78 protein expression began to increase at 1 hour after stretched treatment, was significantly increased at 6 hours, peaked at 24 hours, and significant differences were visible as compared with the control group (P<0.05). In conclusion, cyclic stretch induced the occurrence of endoplasmic reticulum stress, which was enhanced with prolonged time. However, prolonged stretch caused severe endoplasmic reticulum stress and leaded to apoptosis of myoblasts.

Aromatic L-Amino acids are important chiral building blocks for the synthesis of many drugs, pesticides, fine chemicals and food additives. Due to the high activity and steroselectivity, enzymatic synthesis of chiral building blocks has become the main research direction in asymmetric synthesis field. Guided by the phylogenetic analysis of transaminases from different sources, two representative aromatic transaminases TyrB and Aro8 in type I subfamily, from the prokaryote Escherichia coli and eukaryote Saccharomyces cerevisia, respectively, were applied for the comparative study of asymmetric transamination reaction process and catalytic efficiency of reversely converting keto acids to the corresponding aromatic L-amino acid. Both TyrB and Aro8 could efficiently synthesize the natural aromatic amino acids phenylalanine and tyrosine as well as non-natural amino acid phenylglycine. The chiral HPLC analysis showed the produced amino acids were L-configuration and the e.e value was 100%. L-alanine was the optimal amino donor, and the transaminase TyrB and Aro8 could not use D-amino acids as amino donor. The optimal molar ratio of amino donor (L-alanine) and amino acceptor (aromatic alpha-keto acids) was 4:1. Both of the substituted group on the aromatic ring and the length of fatty acid carbon chain part in the molecular structure of aromatic substrate alpha-keto acid have the significant impact on the enzyme-catalyzed transamination efficiency. In the experiments of preparative-scale transamination synthesis of L-phenylglycine, L-phenylalanine and L-tyrosine, the specific production rate catalyzed by TryB were 0.28 g/(g x h), 0.31 g/(g x h) and 0.60 g/(g x h) and the specific production rate catalyzed by Aro8 were 0.61 g/(g x h), 0.48 g/(g x h) and 0.59 g/(g x h). The results obtained here were useful for applying the transaminases to asymmetric synthesis of L-amino acids by reversing the reaction balance in industry.
Amino Acids, Aromatic ; biosynthesis ; genetics ; Catalysis ; Escherichia coli ; enzymology ; Phenylalanine ; biosynthesis ; genetics ; Protein Engineering ; methods ; Saccharomyces cerevisiae ; enzymology ; Stereoisomerism ; Transaminases ; genetics ; metabolism ; Tyrosine ; biosynthesis ; genetics