Suppression of high pacing-induced ANP secretion by antioxidants in isolated rat atria

Reactive oxygen species (ROS) are formed as a natural by-product of the normal metabolism of oxygen and have important roles in cell signaling. The aim of this study was to investigate direct effects of ROS on atrial hemodynamics and ANP secretion in isolated perfused beating rat atria with antioxidants. When atria were paced at 1.2 Hz, N-acetyl cystein (antioxidant, NAC), α-lipoic acid (antioxidant), tempol (superoxide dismutase mimic), and apocynin (NADPH oxidase inhibitor; NOX inhibitor) did not affect ANP secretion and atrial contractility. When pacing frequency was increased from 1.2 Hz to 4 Hz, the ANP secretion increased and atrial contractility decreased. H₂O₂ level was increased in perfusate obtained from atria stimulated by high pacing frequency. NAC, α-lipoic acid and tempol attenuated high pacing frequency-induced ANP secretion but apocynin did not. In contrast, pyrogallol (a superoxide generator) augmented high pacing frequency-induced ANP secretion. NOX-4 protein was increased by high pacing stimulation and in diabetic rat atria. In diabetic rat atria, high pacing frequency caused an increased ANP secretion and a decreased atrial contractility, that were markedly attenuated as compared to control rats. NAC and apocynin reduced high pacing frequency-induced ANP secretion in diabetic rat atria. These results suggest that intracellular ROS formation partly through an increasing NOX activity in response to high pacing frequency is associated with an increased ANP secretion in rat atria.     

Structure-activity relationship of 5'-substituted fluoro-neplanocin a analogues as potent inhibitors of S-adenosylhomocysteine hydrolase

Four 5'-substituted fluoro-neplanocin A analogues la-d were designed and synthesized, and the inhibitory activity against SAH was in the following order: NH2 > SH > F, N3, indicating a hydrogen bonding donor is essential for inhibitory activity.     

Physiological changes and growth promotion induced in poplar seedlings by the plant growth-promoting rhizobacteria Bacillus subtilis JS

Photosynthetica - This study aimed to determine the effects of plant growth-promoting rhizobacteria Bacillus subtilis JS on the growth and physiological changes of Populus euramericana and Populus...     

Growth medium sterilization using decomposition of peracetic acid for more cost-efficient production of omega-3 fatty acids by Aurantiochytrium

Bioprocess and Biosystems Engineering - Aurantiochytrium can produce significant amounts of omega-3 fatty acids, specifically docosahexaenoic acid and docosapentaenoic acid. Use of a glucose-based...     

Production of Aujeszky's disease (pseudorabies) virus envelope glycoproteins gB and gC as recombinant polyhedra in baculovirus-infected silkworm larvae

The expression of viral antigens in baculovirus-infected insect cells is often ineffective. As an alternative approach, therefore, we developed the recombinant polyhedra technology, which is an efficient strategy for the production of viral subunit vaccine. Here, we report a strategy for the large-scale production of a pseudorabies virus (PRV) gB or gC in the larvae of a baculovirus-infected silkworm, Bombyx mori. We constructed a recombinant B. mori nucleopolyhedrovirus (BmNPV) that expressed recombinant polyhedra together with the epitope regions of PRV gB or heparin-binding domains of PRV gC. Recombinant BmNPV-PRV-gB or BmNPV-PRV-gC-infected silkworm larvae expressed native polyhedrin and fusion protein that was detected using both anti-polyhedrin and anti-PRV gB or anti-PRV-gC antibodies. Electron and confocal microscopy demonstrated that the recombinant polyhedra contained both the fusion protein and native polyhedrin with a normal morphology and that the recombinant polyhedra contained PRV gB or gC. The yield of gB or gC antigen produced in BmNPV-PRV-gB or BmNPV-PRV-gC-infected silkworm larvae reached 0.69 or 0.46 mg per larva, respectively, at 6 days post-infection. These results demonstrate that the recombinant polyhedra strategy can be used for the large-scale production of PRV gB or gC antigen.     

An analysis approach to identify specific functional sites in orthologous proteins using sequence and structural information: Application to neuroserpin reveals regions that differentially regulate inhibitory activity

The analysis of sequence conservation is commonly used to predict functionally important sites in proteins. We have developed an approach that first identifies highly conserved sites in a set of orthologous sequences using a weighted substitution‐matrix‐based conservation score and then filters these conserved sites based on the pattern of conservation present in a wider alignment of sequences from the same family and structural information to identify surface‐exposed sites. This allows us to detect specific functional sites in the target protein and exclude regions that are likely to be generally important for the structure or function of the wider protein family. We applied our method to two members of the serpin family of serine protease inhibitors. We first confirmed that our method successfully detected the known heparin binding site in antithrombin while excluding residues known to be generally important in the serpin family. We next applied our sequence analysis approach to neuroserpin and used our results to guide site‐directed polyalanine mutagenesis experiments. The majority of the mutant neuroserpin proteins were found to fold correctly and could still form inhibitory complexes with tissue plasminogen activator (tPA). Kinetic analysis of tPA inhibition, however, revealed altered inhibitory kinetics in several of the mutant proteins, with some mutants showing decreased association with tPA and others showing more rapid dissociation of the covalent complex. Altogether, these results confirm that our sequence analysis approach is a useful tool that can be used to guide mutagenesis experiments for the detection of specific functional sites in proteins. Proteins 2015; 83:135–152. © 2014 Wiley Periodicals, Inc.     

Pleiotrophin inhibits melanogenesis via Erk1/2‐MITF signaling in normal human melanocytes

Pleiotrophin (PTN) is a secreted heparin‐binding protein that is involved in various biological functions of cell growth and differentiation. Little is known about the effects of PTN on the melanocyte function and skin pigmentation. In this study, we investigated whether PTN would affect melanogenesis. PTN was expressed in melanocytes and fibroblasts of human skin. Transfection studies revealed that PTN decreased melanogenesis, probably through MITF degradation via Erk1/2 activation in melanocytes. The inhibitory action of PTN in pigmentation was further confirmed in ex vivo cultured skin and in the melanocytes cocultured with fibroblasts. These findings suggest that PTN is a crucial factor for the regulation of melanogenesis in the skin.     

The molecular weight and concentration of dextran sulfate affect cell growth and antibody production in CHO cell cultures

To investigate the effect of dextran sulfate (DS), a widely used anti‐aggregation agent, on cell growth and monoclonal antibody (mAb) production including the quality attributes, DS with the three different MWs (4,000 Da, 15,000 Da, and 40,000 Da) at various concentrations (up to 1 g/L) was added to suspension cultures of two different recombinant CHO (rCHO) cell lines producing mAb, SM‐0.025 and CS13‐1.00. For both cell lines, the addition of DS, regardless of the MW and concentration of DS used, improved cell growth and viability in the decline phase of growth. However, it increased mAb production only in the CS13‐1.00 cells. Among the three different MWs, 40,000 Da DS was most effective in attenuating cell aggregation during the cultures of CS13‐1.00 cells, and showed the highest maximum mAb concentration. For SM‐0.025 cells, it significantly decreased specific mAb productivity, particularly at a high concentration of DS. Overall, DS addition did not negatively affect the quality attributes of mAbs (aggregation, charge variation, and glycosylation), though its efficacy on mAb quality depended on the MW and concentration of DS and cell lines. For both cell lines, the addition of DS did not affect N‐glycosylation of mAbs and decreased basic charge variants in mAbs. For CS13‐1.00 cells, the mAb monomer increased with the addition of 40,000 Da DS at 0.3–1.0 g/L. Taken together, to maximize the beneficial effect of DS addition on mAb production, the optimal MW and concentration of DS should be determined for each specific rCHO cell line. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1113–1122, 2016     

Effect of pinocembrin isolated from Alpinia zerumbet on osteoblast differentiation

Cytotechnology - Bone mass is regulated by osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Osteoporosis is a bone metabolism disorder in which bone mass decreases due to...     

Dynamic Alterations to α-Actinin Accompanying Sarcomere Disassembly and Reassembly during Cardiomyocyte Mitosis

Although mammals are thought to lose their capacity to regenerate heart muscle shortly after birth, embryonic and neonatal cardiomyocytes in mammals are hyperplastic. During proliferation these cells need to selectively disassemble their myofibrils for successful cytokinesis. The mechanism of sarcomere disassembly is, however, not understood. To study this, we performed a series of immunofluorescence studies of multiple sarcomeric proteins in proliferating neonatal rat ventricular myocytes and correlated these observations with biochemical changes at different cell cycle stages. During myocyte mitosis, α-actinin and titin were disassembled as early as prometaphase. α-actinin (representing the sarcomeric Z-disk) disassembly precedes that of titin (M-line), suggesting that titin disassembly occurs secondary to the collapse of the Z-disk. Sarcomere disassembly was concurrent with the dissolution of the nuclear envelope. Inhibitors of several intracellular proteases could not block the disassembly of α-actinin or titin. There was a dramatic increase in both cytosolic (soluble) and sarcomeric α-actinin during mitosis, and cytosolic α-actinin exhibited decreased phosphorylation compared to sarcomeric α-actinin. Inhibition of cyclin-dependent kinase 1 (CDK1) induced the quick reassembly of the sarcomere. Sarcomere dis- and re-assembly in cardiomyocyte mitosis is CDK1-dependent and features dynamic differential post-translational modifications of sarcomeric and cytosolic α-actinin.