Apoptosis signal-regulating kinase 1 is an intracellular inducer of p38 MAPK-mediated myogenic signalling in cardiac myoblasts

Myogenic differentiation is an essential process for the myogenesis in response to various extracellular stimuli. p38 MAPK is a core signalling molecule in myogenic differentiation. The activation of p38 MAPK is required for myogenic differentiation; however, the mechanism for this activation remains undefined. ASK1 is a member of the MAP3K family that activates both JNK and p38 MAPK pathways in response to an array of stresses such as oxidative stress, endoplasmic reticulum stress and calcium influx. Here, we reported that TNFα was significantly released from H9c2 cardiac myoblast in differentiation medium. Furthermore, the oxidant H₂O₂ acted as a messenger in the TNFα signalling pathway to disrupt the complex of ASK1-Trx, which was followed by the activation of ASK1 in cardiac myogenic differentiation. Subsequently, the activated ASK1 stimulated MKK3/6-p38MAPK signalling cascade to induce specific myogenic differentiation. In addition, exogenous TNFα added to the medium at physiological levels enhanced the ASK1-p38 MAPK signalling pathway through the increased generation of H₂O₂. Interestingly, inhibition of p38 MAPK abrogated the production of H₂O₂, suggesting that there might be a positive feedback loop in the myogenic-redox signalling pathway. These results indicate that ASK1 is a new intracellular regulator of activation of the p38 MAPK in cardiac myogenic differentiation.     

Jabuticaba‐Inspired Hybrid Carbon Filler/Polymer Electrode for Use in Highly Stretchable Aqueous Li‐Ion Batteries

Stretchable electronics are considered as next‐generation devices; however, to realize stretchable electronics, it is first necessary to develop a deformable energy device. Of the various components in energy devices, the fabrication of stretchable current collectors is crucial because they must be mechanically robust and have high electrical conductivity under deformation. In this study, the authors present a conductive polymer composite composed of Jabuticaba‐like hybrid carbon fillers containing carbon nanotubes and carbon black in a simple solution process. The hybrid carbon/polymer (HCP) composite is found to effectively retain its electrical conductivity, even when under high strain of ≈200%. To understand the behavior of conductive fillers in the polymer matrix when under mechanical strain, the authors investigate the microstructure of the composite using an in situ small‐angle X‐ray scattering analysis. The authors observe that the HCP produces efficient electrical pathways for filler interconnections upon stretching. The authors develop a stretchable aqueous rechargeable lithium‐ion battery (ARLB) that utilizes this HCP composite as a stretchable current collector. The ARLB exhibits excellent rate capability (≈90 mA h g^?1 at a rate of 20 C) and outstanding capacity retention of 93% after 500 cycles. Moreover, the stretchable ARLB is able to efficiently deliver power even when under 100% strain.     

Molecular Dissection of the Rho-associated Protein Kinase (p160ROCK)-regulated Neurite Remodeling in Neuroblastoma N1E-115 Cells

A critical role for the small GTPase Rho and one of its targets, p160ROCK (a Rho-associated coiled coil-forming protein kinase), in neurite remodeling was examined in neuroblastoma N1E-115 cells. Using wild-type and a dominant-negative form of p160ROCK and a p160ROCK-specific inhibitor, Y-27632, we show here that p160ROCK activation is necessary and sufficient for the agonist-induced neurite retraction and cell rounding. The neurite retraction was accompanied by elevated phosphorylation of myosin light chain and the disassembly of the intermediate filaments and microtubules. Y-27632 blocked both neurite retraction and the elevation of myosin light chain phosphorylation in a similar concentration-dependent manner. On the other hand, suppression of p160ROCK activity by expression of a dominant-negative form of p160ROCK induced neurites in the presence of serum by inducing the reassembly of the intermediate filaments and microtubules. The neurite outgrowth by the p160ROCK inhibition was blocked by coexpression of dominant-negative forms of Cdc42 and Rac, indicating that p160ROCK constitutively and negatively regulates neurite formation at least in part by inhibiting activation of Cdc42 and Rac. The assembly of microtubules and intermediate filaments to form extended processes by inhibitors of the Rho–ROCK pathway was also observed in Swiss 3T3 cells. These results indicate that Rho/ROCK-dependent tonic inhibition of cell process extension is exerted via activation of the actomysin-based contractility, in conjunction with a suppression of assembly of intermediate filaments and microtubules in many cell types including, but not exclusive to, neuronal cells.     

Hamster PIWI proteins bind to piRNAs with stage-specific size variations during oocyte maturation

In animal gonads, transposable elements are actively repressed to preserve genome integrity through the PIWI-interacting RNA (piRNA) pathway. In mice, piRNAs are abundantly expressed in male germ cells, and form effector complexes with three distinct PIWIs. The depletion of individual Piwi genes causes male-specific sterility with no discernible phenotype in female mice. Unlike mice, most other mammals have four PIWI genes, some of which are expressed in the ovary. Here, purification of PIWI complexes from oocytes of the golden hamster revealed that the size of the PIWIL1-associated piRNAs changed during oocyte maturation. In contrast, PIWIL3, an ovary-specific PIWI in most mammals, associates with short piRNAs only in metaphase II oocytes, which coincides with intense phosphorylation of the protein. An improved high-quality genome assembly and annotation revealed that PIWIL1- and PIWIL3-associated piRNAs appear to share the 5′-ends of common piRNA precursors and are mostly derived from unannotated sequences with a diminished contribution from TE-derived sequences, most of which correspond to endogenous retroviruses. Our findings show the complex and dynamic nature of biogenesis of piRNAs in hamster oocytes, and together with the new genome sequence generated, serve as the foundation for developing useful models to study the piRNA pathway in mammalian oocytes.     

Species specificity of barnacle settlement-inducing proteins

We previously isolated a larval settlement-inducing protein complex (SIPC) from adult extracts of the barnacle, Balanus amphitrite using a nitrocellulose membrane settlement assay. In the present study, we found that the extracts of other adult barnacles, Megabalanus rosa and Balanus eburneus, also induced the settlement of B. amphitrite cyprids although the inductive activity was slightly lower than that of conspecific extracts. Furthermore, we examined reactivity to anti-SIPC antibody in adult extracts from six species of Japanese barnacles other than B. amphitrite, brine shrimp and eight marine sessile organisms besides barnacles. The results showed that all barnacles examined contained SIPC-like proteins with slightly different molecular weight, while the other animals did not react to the antibody by immunoblot analysis. These findings suggest that species specificity in settlement-inducing proteins of barnacles is not so strict, but these proteins are characteristic to barnacle species.     

Effect of Transient Cerebral Ischemia on the Expression of Receptor for Advanced Glycation End Products (RAGE) in the Gerbil Hippocampus Proper

The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor of the immunoglobulin superfamily that has been implicated in multiple neuronal and inflammatory stress processes. In this study, we examined changes in RAGE immunoreactivity and its protein levels in the gerbil hippocampus (CA1-3 regions) after 5 min of transient global cerebral ischemia. The ischemic hippocampus was stained with cresyl violet, neuronal nuclei (a neuron-specific soluble nuclear antigen) antibody and Fluoro-Jade B (a marker for neuronal degeneration). 5 days after ischemia–reperfusion, delayed neuronal death occurred in the stratum pyramidale of the CA1 region. RAGE immunoreactivity was not detected in any regions of the CA1-3 regions of the sham-group; the immunoreactivity was markedly increased only in the CA1 region from 3 days after ischemia–reperfusion. On the other hand, RAGE immunoreactivity was newly expressed in astrocytes, not in microglia. Western blot analysis showed that RAGE protein level was highest at 5 days post-ischemia. In brief, both the RAGE immunoreactivity and protein level were distinctively increased in astrocytes in the ischemic CA1 region from 3 days after transient cerebral ischemia. These results indicate that the increase of RAGE expression in astrocytes after ischemia–reperfusion may be related to the ischemia-caused activation of astrocytes in the ischemic CA1 region.     

Attractiveness of conspecific stink bugs to adult stink bug-baited traps in soybean fields

The attractiveness of live adult stink bugs used as baits in traps in soybean fields, Milyang, Korea, to conspecific stink bugs was evaluated. Both sexes of bean bug, Riptortus pedestris Fabricius (Hemiptera: Alididae), and one-banded stink bug, Piezodorus hybneri Gmelin (Hemiptera: Pentatomidae), were attracted to conspecific male adults-baited traps. Likewise, both sexes of brown-marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), and sole bug, Dolycoris baccarum L. (Hemiptera: Pentatomidae), were attracted to traps baited with conspecific male stink bugs. However, in Nezara antennata Scott (Hemiptera: Pentatomidae), both male and female used as baits in traps were attractive to conspecific adults. Accordingly, these results suggest that the only male adults of H. halys and D. baccarum and both sexes of N. antennata are attractive to conspecific male stink bugs.     

Medium composition for effective slow freezing of embryonic cell lines derived from marine medaka (Oryzias dancena)

This study was conducted to identify optimal medium composition for freezing Oryzias dancena embryonic cell lines. Different freezing media consisting of various concentration of dimethyl sulfoxide (DMSO), fetal bovine serum (FBS), and trehalose were prepared and long-term cultured embryonic cell line was frozen in each freezing medium by conventional slow freezing program for 7 days. Through measurement of viability and growth of post-thaw cells frozen in each freezing medium, it was determined that optimal composition of three components was 10 % DMSO, 20 % FBS, and 0.1 M trehalose. The post-thaw cells frozen in optimal freezing medium showed similar morphology and growth rate with non-frozen cells. Next, this condition was applied to two different sets of experiment; (1) freezing of the same cells during expanded period (57 days) and (2) freezing of short-term cultured cells from other batches for 7 days. The viability of post-thaw cells was significantly low and comparable in set 1 and 2, respectively, when compared with the result of long term-cultured cells frozen in optimal freezing medium for 7 days and similar morphology and growth rate with non-frozen counterparts were detected in the post-thaw cells from both sets. In conclusion, this study first reports the optimal medium composition for freezing O. dancena embryonic cells, which can contribute to fish species preservation as well as improvement of cell-based biotechnology by providing stable cell storage.