Mechanism of oxidative damage to fish red blood cells by ozone

The present study was conducted to elucidate the adverse effects of ozone exposure on rainbow trout (Oncorhynchus mykiss) red blood cells (RBCs). We evaluated whether hemoglobin (Hb) or Hb-derived free iron could participate in the RBC damage using an in vitro ozone exposure system. Ozone exposure induced hemolysis, formation of methemoglobin, and RBC membrane lipid peroxidation. This RBC damage was not suppressed by the addition of a specific iron chelator (deferoxamine mesilate) to the medium but was suppressed by carbon monoxide (CO) treatment before ozone exposure. Generation of hydrogen peroxide (H2O2) in RBC was observed upon ozone exposure but was significantly suppressed by CO treatment before ozone exposure. Thus the Hb status (i.e., Hb redox condition) and H2O2 generation in RBC should play important roles in mediating RBC damage by ozone exposure. In other words, neither ozone nor its derivative directly attacked from the outside of the cell, but ozone that penetrated through the membrane derived the reactive oxygen species from Hb inside of the cell.     

Role of alpha-tocopherol in the regulation of mitochondrial permeability transition

We previously showed that Ca2+-induced cyclosporin A-sensitive membrane permeability transition (MPT) of mitochondria occurred with concomitant generation of reactive oxygen species (ROS) and release of cytochrome c (Free Rad. Res.38, 29-35, 2004). To elucidate the role of alpha-tocopherol in MPT, we investigated the effect of alpha-tocopherol on mitochondrial ROS generation, swelling and cytochrome c release induced by Ca2+ or hydroxyl radicals. Biochemical analysis revealed that alpha-tocopherol suppressed Ca2+-induced ROS generation and oxidation of critical thiol groups of mitochondrial adenine nucleotide translocase (ANT) but not swelling and cytochrome c release. Hydroxyl radicals also induced cyclosporin A-sensitive MPT of mitochondria. alpha-Tocopherol suppressed the hydroxyl radical-induced lipid peroxidation, swelling and cytochrome c release from mitochondria. These results indicate that alpha-tocopherol inhibits ROS generation, ANT oxidation, lipid peroxidation and the opening of MPT, thereby playing important roles in the prevention of oxidative cell death.     

Isolation of a cadmium-releasing bacterium and characterization of its novel protease

Microorganisms were screened for their ability to release cadmium from scallop hepatopancreas, which is the main residue after removing of the edible parts of scallop. The isolated strain, 23-0-11, identified as Arthrobacter nicotinovorans, secreted a protease which released cadmium from scallop hepatopancreas into the liquid medium. The molecular mass of the enzyme was estimated to be 27 kDa. The sequence of the 15 N-terminal amino acids of the protease showed no close similarity with any other protein. Compared with a commercial enzyme, the purified protease had greater ability to release cadmium. The enzyme activity was greatest at 50 degrees C and pH 7.0, and was enhanced in the presence of Ca(2+), Mg(2+) and Mn(2+), while being strongly inhibited by Co(2+). The inhibition profile by the serine protease inhibitor, phenylmethylsulphonyl fluoride (PMSF), confirmed that the protease belonged to the serine protease family.     

Synthesis and biological evaluation of (-)-laulimalide analogues

Analogues of the marine natural product (-)-laulimalide were prepared by total synthesis and evaluated in vitro for anticancer activity.     

Free radical theory of apoptosis and metamorphosis

Reactive oxygen species (ROS) are the major factors that induce oxidative modification of DNA and gene mutation. ROS can elicit oxidative stress and affect a wide variety of physiological and pathological processes including embryonal development, maturation and aging.     

Interaction with IQGAP1 links APC to Rac1, Cdc42, and actin filaments during cell polarization and migration

Rho family GTPases, particularly Rac1 and Cdc42, are key regulators of cell polarization and directional migration. Adenomatous polyposis coli (APC) is also thought to play a pivotal role in polarized cell migration. We have found that IQGAP1, an effector of Rac1 and Cdc42, interacts directly with APC. IQGAP1 and APC localize interdependently to the leading edge in migrating Vero cells, and activated Rac1/Cdc42 form a ternary complex with IQGAP1 and APC. Depletion of either IQGAP1 or APC inhibits actin meshwork formation and polarized migration. Depletion of IQGAP1 or APC also disrupts localization of CLIP-170, a microtubule-stabilizing protein that interacts with IQGAP1. Taken together, these results suggest a model in which activation of Rac1 and Cdc42 in response to migration signals leads to recruitment of IQGAP1 and APC which, together with CLIP-170, form a complex that links the actin cytoskeleton and microtubule dynamics during cell polarization and directional migration.     

Synthesis of amide compounds of ferulic acid,and their stimulatory effects on insulin secretion in vitro

We prepared amide compounds which were derived from ferulic acid using various amines, and investigated their stimulatory effects on insulin secretion using rat pancreatic RIN-5F cells. Most of these compounds exhibited significant promotion of the insulin-release at a concentration of 10 microM and in particular, the amides having n-butyl, n-pentyl, pyrrolidine, and piperidine groups showed high activity.