Effect of electrical stimulation of antagonist muscles for voluntary motor drive

Voluntary motor drive is an important central command that descends via the corticospinal tract to initiate muscle contraction. When electrical stimulation (ES) is applied to an antagonist or agonist muscle, it changes the agonist muscle’s representative motor cortex and thus its voluntary motor drive. In this study, we used a reaction time task to compare the effects of weak and strong ES of the antagonist or agonist muscle during the premotor period of a wrist extension. We recorded motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) that was applied to the extensor carpi radialis (ECR; agonist) and flexor carpi radialis (FCR; antagonist). When stronger ES intensities were applied to the antagonist, the MEP control ratio in the ECR significantly increased during the premotor time. Furthermore, the MEP control ratio with stronger antagonist ES intensity was significantly larger than that in the agonist for the same ES intensity. In the FCR, the MEP control ratio was also significantly greater at the strong ES intensity than at the weak ES intensity. Furthermore, the MEP control ratio in the antagonist with a strong ES intensity was significantly larger than that in the agonist with the same ES intensity. These results suggest that agonist corticomotor excitability might be enhanced by ES of the antagonist, which in turn strongly activates the descending motor system in the preparation of agonist contraction.     

Norlichexanthone produced by cultured endolichenic fungus induced from Pertusaria laeviganda and its antioxidant activity

Endolichenic fungi, nonobligate microfungi that live in lichen, are promising as new bioresources of pharmacological compounds. We found that norlichexanthone isolated from the endolichenic fungus in Pertusaria laeviganda exhibited high antioxidant activity. Norlichexanthone produced by endolichenic fungus had the antioxidant activity with same level of ascorbic acid. This is the first report of high antioxidant activity of norlichexanthone.

Abbreviations: AAPH: 2,2?-azobis (2-methylpropionamidine) dihydrochloride; DPPH: 2,2-diphenyl-1-picrylhydrazyl; FL: fluorescein sodium salt; HPLC-PDA: high-performance liquid chromatography with photodiode array; LC-ESI-MS: liquid chromatography with electrospray ionization mass spectrometry; ORAC: oxygen radical absorbance capacity; PB: phosphate buffer; ROS: reactive oxygen species; TLC: thin-layer chromatography     

Population genetic structure and demography of Magnolia kobus: variety borealis is not supported genetically

Species delimitations by morphological and by genetic markers are not always congruent. Magnolia kobus consists of two morphologically different varieties, kobus and borealis. The latter variety is characterized by larger leaves than the former. For the conservation of M. kobus genetic resources in natural forests, the relationships between morphological and genetic variation should be clarified. We investigated variations in nuclear microsatellites, chloroplast DNA (cpDNA) sequences and leaf morphological traits in 23 populations of M. kobus over the range of species. Two genetically divergent lineages, northern and southern were detected and their geographical boundary was estimated to be at 39°N. The northern lineage consisted of two genetic clusters and a single cpDNA haplotype, while the southern one had multiple genetic clusters and cpDNA haplotypes. The northern lineage showed significantly lower genetic diversity than the southern. Approximate Bayesian computation indicated that the northern and southern lineages had experienced, respectively, population expansion and long-term stable population size. The divergence time between the two lineages was estimated to be 565,000 years ago and no signature of migration between the two lineages after divergence was detected. Ecological niche modeling showed that the potential distribution area in northern Japan at the last glacial maximum was very small. It is thus considered that the two lineages have experienced different population histories over several glacial-inter-glacial cycles. Individuals of populations in the central to northern part of Honshu on the Sea of Japan side and in Hokkaido had large leaf width and area. These leaf characteristics corresponded with those of variety borealis. However, the delimitation of the northern and southern lineages detected by genetic markers (39°N) was not congruent with that detected by leaf morphologies (36°N). It is therefore suggested that variety borealis is not supported genetically and the northern and southern lineages should be considered separately when identifying conservation units based not on morphology but on genetic markers.

     

Hsp105α suppresses Adriamycin-induced cell death via nuclear localization signal-dependent nuclear accumulation

Heat shock protein 105 (Hsp105) is a molecular chaperone, and the isoforms Hsp105α and Hsp105β exhibit distinct functions with different subcellular localizations. Hsp105β localizes in the nucleus and induces the expression of the major heat shock protein Hsp70, whereas cytoplasmic Hsp105α is less effective in inducing Hsp70 expression. Hsp105 shuttles between the cytoplasm and the nucleus; the subcellular localization is governed by the relative activities of the nuclear localization signal (NLS) and nuclear export signal (NES). Here, we show that nuclear accumulation of Hsp105α but not Hsp105β is involved in Adriamycin (ADR) sensitivity. Knockdown of Hsp105α induces cell death at low ADR concentration, at which ADR is less effective in inducing cell death in the presence of Hsp105α. Of note, Hsp105 is localized in the nucleus under these conditions, even though Hsp105β is not expressed, indicating that Hsp105α accumulates in the nucleus in response to ADR treatment. The exogenously expressed Hsp105α but not its NLS mutant localizes in the nucleus of ADR-treated cells. In addition, the expression level of the nuclear export protein chromosomal maintenance 1 (CRM1) was decreased by ADR treatment of cells, and CRM1 knockdown caused nuclear accumulation of Hsp105α both in the presence and absence of ADR. These results indicating that Hsp105α accumulates in the nucleus in a manner dependent on the NLS activity via the suppression of nuclear export. Our findings suggest a role of nuclear Hsp105α in the sensitivity against DNA-damaging agents in tumor cells.     

Molecular monitoring of bleomycin-induced pulmonary fibrosis by cDNA microarray-based gene expression profiling.

Pulmonary fibrosis is a progressive disorder whose molecular pathology is poorly understood. Here we developed an in-house cDNA microarray ("lung chip") originating from a lung-normalized cDNA library. By using this lung chip, we analyzed global gene expression in a murine model of bleomycin-induced fibrosis and selected 82 genes that differed by more than twofold intensity in at least one pairwise comparison with controls. Cluster analysis of these selected genes showed that the expression of genes associated with inflammation reached maximum levels at 5 days after bleomycin administration, while genes involved in the development of fibrosis increased gradually up to 14 days after bleomycin treatment. These changes in gene expression signature were well correlated with observed histopathological changes. The results show that microarray analysis of animal disease models is a powerful approach to understanding the gene expression programs that underlie these disorders.     

Apoptosis induction by epigallocatechin gallate involves its binding to Fas

Epigallocatechin gallate (EGCG) is known to induce apoptosis in various types of tumor cells, but the precise mechanism by which EGCG induces apoptosis remains to be elucidated. The Fas-Fas ligand system is one of the major pathways operating in the apoptotic cascade. The aim of this study was to examine the possibility that EGCG-binding to Fas triggers the Fas-mediated apoptosis. The EGCG treatment of human monocytic leukemia U937 cells resulted in elevation of caspase 8 activity and fragmentation of caspase 8. The DNA ladder formation caused by the EGCG treatment was inhibited by the caspase 8 inhibitor. These findings suggested the involvement of the Fas-mediated cascade in the EGCG-induced apoptosis in U937 cells. Affinity chromatography revealed the binding between EGCG and Fas. Thus, the results suggest that EGCG-binding to Fas, presumably on the cell surface, triggers the Fas-mediated apoptosis in U937 cells.     

Mouse coq7/clk-1 orthologue rescued slowed rhythmic behavior and extended life span of clk-1 longevity mutant in Caenorhabditis elegans

The coq7/clk-1 gene was isolated from the long-lived mutant of Caenorhabditis elegans and was suggested to play a regulatory role in biological rhythm and longevity. The mouse COQ7 is homologous to Saccharomyces cerevisiae COQ7/CAT5 that is required for the biosynthesis of coenzyme Q (ubiquinone), an essential messenger in mitochondrial respiration. In the present study, we characterized the expression and processing of mouse COQ7. We found that COQ7 is highly expressed in tissues with high energy demand such as heart, muscle, liver, and kidney in mice. Biochemical analysis revealed that COQ7 is targeted to mitochondria where it is processed to mature form. Transgenic expression of mouse coq7 completely rescued the slowed rhythmic behaviors of clk-1 such as defecation. In life-span analysis, transgenic expression reverted the extended life span of clk-1 to the comparable level with wild-type control. These data strongly suggested that coq7 plays a pivotal role in the regulation of biological rhythms and the determination of life span in mammalian species.     

Selective isolation and distribution of the genus Planomonospora in soils

For the screening of bioactive compounds and study of global distribution, a selective isolation method for Planomonospora strains by centrifugation from soil is examined. Planomonospora strains produced characteristic sporangia on the humic acid-trace salts gellan gum medium (pH 9.0) so that this genus was readily recognized on the isolation plate. High yields of motile spores were obtained by using a flooding solution containing 0.1% skim milk in 5 mM N-cyclohexyl-2-amino-ethanesulfonic acid (pH 9.0) followed by incubating the preparation at 32 degreesC for 90 min, centrifuging it at 1000 x g for 10 min, and further incubation at 32 degreesC for 60 min after centrifugation. By combining the techniques described above, we isolated 246 Planomonospora strains from 137 of the 1200 soil samples examined. Ninety-four percent of these strains were recovered from neutral to slightly alkaline soils (pH 7.0 to 9.0). Strains of P. venezuelensis group were obtained from 13 soil samples (1.1%), which were collected in Bolivia, Cyprus, Egypt, Greece, India, Japan, New Caledonia, and Turkey. Strains of this group appear widely distributed in the soil of tropical to temperate regions. To our knowledge, this is the first record that strains of this group have been isolated from a location other than Venezuela.     

X-linked inhibitor of apoptosis protein (XIAP) inhibits caspase-3 and -7 in distinct modes

The inhibitor of apoptosis proteins (IAP) regulates cell death by inhibiting caspases. The region of X-linked (X) IAP containing the second baculovirus IAP repeat domain (BIR2) is sufficient for inhibiting caspase-3 and -7. In this study, we found that the modes of inhibition of these two caspases were different: caspase-3 is inhibited in a competitive manner whereas caspase-7 inhibition occurs through a mixed competitive and noncompetitive mechanism. Binding assays revealed that the inhibition of caspase-3 by XIAP was totally dependent on the interaction between the active site of caspase-3 and the linker region between the BIR1 and BIR2 domains of XIAP. In contrast, the active site and the NH(2)-terminal region of caspase-7 bound to the linker region and the BIR2, respectively. Moreover the BIR2 with a mutated linker region, which inhibited caspase-3 very weakly, still bound to and inhibited caspase-7. Furthermore, a chimeric caspase-7/3 comprising the NH(2)-terminal portion of caspase-7 and COOH-terminal portion of caspase-3 was inhibited by XIAP by a mixed competitive and noncompetitive mechanism. Our results suggest that the linker region between BIR1 and BIR2 domains is responsible for active site-directed, competitive inhibition of both caspase-3 and -7, whereas the BIR2 itself is involved in noncompetitive inhibition of caspase-7.