Activation of Nrf2/Keap1 signaling and autophagy induction against oxidative stress in heart in iron deficiency

We investigated the effects of dietary iron deficiency on the redox system in the heart. Dietary iron deficiency increased heart weight and accumulation of carbonylated proteins. However, expression levels of heme oxygenase-1 and LC3-II, an antioxidant enzyme and an autophagic marker, respectively, in iron-deficient mice were upregulated compared to the control group, resulting in a surrogate phenomenon against oxidative stress.     

Role of calcium-binding sites in calcium-dependent membrane association of annexin A4

Annexin A4 (Anx4) is a cytosolic calcium-binding protein with four repeat domains, each containing one calcium-binding site (CBS). The protein interacts with the phospholipid membrane through the CBS-coordinated calcium ion, although the role of each CBS in the calcium-dependent association is unclear. To determine the role of each CBS, 15 CBS-abolished variants were produced in various combinations by substitution of a calcium-liganding residue on each CBS by Ala. Various mutant combinations produced different influences on calcium-dependent membrane-binding behavior and on the sodium-dependent dissociation of membrane-bound Anx4. Our data suggest the interaction of Anx4 with the lipid membrane consists of strong and weak interactions. CBSs I and IV mediate formation of strong interactions, while CBSs II and III are important for weak interactions. We also suggest Anx4 binds the lipid membrane through CBSs I and IV in the cytoplasmic fluids.     

alpha-Tomatine, the major saponin in tomato, induces programmed cell death mediated by reactive oxygen species in the fungal pathogen Fusarium oxysporum

The tomato saponin alpha-tomatine has been proposed to kill sensitive cells by binding to cell membranes followed by leakage of cell components. However, details of the modes of action of the compound on fungal cells are poorly understood. In the present study, mechanisms involved in alpha-tomatine-induced cell death of fungi were examined using a filamentous pathogenic fungus Fusarium oxysporum. alpha-Tomatine-induced cell death of F. oxysporum (TICDF) occurred only under aerobic conditions and was blocked by the mitochondrial F(0)F(1)-ATPase inhibitor oligomycin, the caspase inhibitor D-VAD-fmk, and protein synthesis inhibitor cycloheximide. Fungal cells exposed to alpha-tomatine showed TUNEL-positive nuclei, depolarization of transmembrane potential of mitochondria, and reactive oxygen species (ROS) accumulation. These results suggest that TICDF occurs through a programmed cell death process in which mitochondria play a pivotal role. Pharmacological studies using inhibitors suggest that alpha-tomatine activates phosphotyrosine kinase and monomeric G-protein signaling pathways leading to Ca(2+) elevation and ROS burst in F. oxysporum cells.     

Purification and some properties of ornithine decarboxylase from rat liver

Ornithine decarboxylase (EC 4.1.1.17) was purified to near homogeniety from livers of thioacetamide- and dl-α-hydrazino-δ-aminovaleric acid-treated rats by using three types of affinity chromatography with pyridoxamine phosphate-Sepharose, pyridoxamine phosphate-dipropylenetriamine-Sepharose and heparin-Sepharose. This procedure gave a purification of about 3.5·10⁵-fold with an 8% yield; the specific activity of the final enzyme preparation was 1,1·10⁶ nmol CO₂/h per mg protein. The purified enzyme gave a single band of protein which coincided with activity peak on polyacrylamide gel electrophoresis and also gave a single major band on SDS-polyacrylamide gel electrophoresis. A single precipitin line was formed between the purified enzyme and an antiserum raised against a partially purified enzyme, on Ouchterlony immunodiffusion. The molecular weight of the enzyme was estimated to be 105 000 by polyacrylamide gel electrophoresis at several different gel concentrations; the dissociated subunits had molecular weights of 50 000 on SDS-polyacrylmide gels. The isoelectric point of the enzyme was pH 4.1.     

Gap dynamics in climaxFagus crenata forests

Gap characteristics and gap regeneration were studied in several climaxFagus crenata forests in Japan. 278 gaps were observed. Gaps covered 12% of the total land area of 20.05 ha. Gap density was 13.9 gaps per ha and, mean gap size was 92.0 m². Smaller gaps were much more frequent than larger ones. Gaps larger than 400 m² were rare. Most gaps were created by the death of single trees. Canopy trees died more often standing or with broken trunks than by uprooting, although uprooted trees were relatively abundant in the site with poor soil drainage and in the site on upper slope. Differences of gap regeneration behaviour were recognized among tree species.F. crenata regenerates in gaps from saplings recruited before gap creation and can replace not only its own gaps but also gaps of other species. Most species other thanF. crenata andMagnolia obovata could not regenerate in their own gaps. More successful regeneration ofF. crenata may occur in gaps smaller than 200 m², althought it regenerated in a wide range of gap size. However, increased relative density ofF. crenata in the canopy layer seems to prevent its successful regeneration. Gap regeneration of other species did not clearly depend on a species-specific gap size.     

Gap regeneration in primary evergreen broad-leaved forests with or without a major canopy tree,Distylium racemosum,southwestern Japan: A comparative analysis

Gap regeneration was studied in a typical primary evergreen broad-leaved forest withoutDistylium racemosum, at the Kasugayama Forest Reserve, southwestern Japan and the results were compared with those from other primary evergreen broad-leaved forests in southwestern Japan, whereD. racemosum was the dominant species. Several common types of gap regeneration behavior were recognized among the major tree species and forests with or withoutD. racemosum consisted of three typical regeneration guilds which could be detected in the principal component analysis.Castanopsis cuspidata frequently regenerated in gaps from saplings recruited before gap formation in the forest withoutD. racemosum, although elsewhere, in forests withD. racemosum, it lacked advanced regeneration and regenerated in gaps from saplings recruited after gap formation. Some evergreenQuercus had their regenerations in gaps of the forest withoutD. racemosum, although elsewhere, in forests withD. racemosum, evergreenQuercus might not regenerate. The results indicate that tree species may change their regeneration behavior depending on the presence or absence of another key dominant species. This suggests that the presence and the dominance of a potential competitor induces shifts in the regeneration niche of other coexisting tree species.     

Human recombinant stem cell factor promotes spermatogonial proliferation,but not meiosis initiation in organ culture of newt testis fragments

We previously showed that mammalian FSH stimulates the proliferation of newt spermatogonia and induces their differentiation into primary spermatocytes in vitro. In the current study, to examine a possibility that stem cell factor (SCF) is involved in the proliferation of newt spermatogonia and/or their differentiation into primary spermatocytes, human recombinant SCF (rhSCF) was added to organ culture of testicular fragments. rhSCF was found to stimulate the spermatogonial proliferation and the spermatogonia progressed to the seventh generation that is the penultimate stage before primary spermatocyte stage. However, the spermatogonia did not differentiate into primary spermatocytes, but instead died of apoptosis. These results indicate that rhSCF promotes the proliferation of newt spermatogonia, but not the initiation of meiosis.     

Conversion of DOPA to tetrahydroisoquinolines and stizolobic acid in a callus culture of Stizolobium hassjoo

Isolation and identification of l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline from seeds and callus of S. hassjoo are described. Administration of [β-¹⁴C]-labelled DOPA to a callus culture of this legume resulted in the incorporation of radioactivity into l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, l-1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and stizolobic acid, which was confirmed by constant specific radioactivity after co-crystallization with authentic samples of each compound.     

Differential salt tolerance of two Artemisia species growing in contrasting coastal habitats

To investigate factors determining the differences in their salt tolerance, growth and germination, experiments were conducted on two plant species belonging to genus Artemisia: Artemisia fukudo Makino, a biennial salt marsh plant and Artemisia stelleriana Bess, a perennial coastal hind dune plant. Growth experiments revealed that salinity (100 and 300 m m NaCl) inhibited the relative growth rate (RGR) in A. stelleriana significantly but not in A. fukudo. These specific differences in salt tolerance were mainly attributed to differential responses of net assimilation rate (NAR). That is, the reduction in RGR in A. stelleriana was mainly due to the reduction in NAR, whereas no significant reduction in NAR was observed in A. fukudo. The reduction in RGR in A. stelleriana in the salt treatment was also attributable to a reduced leaf area ratio (LAR). Specific leaf area (SLA) in the two species decreased in the 300 m m treatment. The decrease in SLA in A. fukudo was, however, compensated for partly by an increase in leaf weight ratio (LWR). Germination experiments also showed that A. fukudo has a higher salt tolerance than does A. stelleriana. These results are consistent with the differences in the salinity conditions between the native habitats of the two species.