Lifespan and reproduction in brain-specific miR-29-knockdown mouse.

The microRNA miR-29 is widely distributed and highly expressed in adult mouse brain during the mouse's lifetime. We recently created conditional mutant mice whose miR-29 was brain-specifically knocked down through overexpression of an antisense RNA transgene against miR-29. To explore a role for brain miR-29 in maximizing organismal fitness, we assessed somatic growth, reproduction, and lifespan in the miR-29-knockdown (KD) mice and their wild-type (WT) littermates.

Post-translational activation of non-selenium glutathione peroxidase of by specific incorporation of selenium.

Glutathione peroxidase (GPX) plays a pivotal role in the protection of cells against oxidative damage. The green alga expresses both selenocysteine-containing GPX and the non-selenium GPX homolog (GPXH). We previously reported that supplementation of selenium to algal culture induces GPXH to exhibit GPX activity.

Possible role of NAD-dependent glyceraldehyde-3-phosphate dehydrogenase in growth promotion of Arabidopsis seedlings by low levels of selenium.

We explored functional significance of selenium (Se) in Arabidopsis physiology. Se at very low concentrations in cultivation exerted a considerable positive effect on Arabidopsis growth with no indication of oxidative stress, whereas Se at higher concentrations significantly suppressed the growth and brought serious oxidative damage. Respiration, ATP levels, and the activity of NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (NAD-GAPDH) were enhanced in Arabidopsis grown in the medium containing 1.

The combination of strong immunohistochemical mtTFA expression and a high survivin index predicts a shorter disease-specific survival in pancreatic ductal adenocarcinoma.

Mitochondrial transcription factor A (mtTFA) plays a crucial role in both the transcription and maintenance of mitochondrial DNA. A high expression of mtTFA has been demonstrated in several solid tumors, and is closely associated with cancer cell survival/apoptosis and growth. However, its expression pattern in pancreatic ductal adenocarcinoma (PAC) remains to be elucidated.

The combination of a nuclear HMGB1-positive and HMGB2-negative expression is potentially associated with a shortened survival in patients with pancreatic ductal adenocarcinoma.

High-mobility group box (HMGB) proteins are ubiquitous, abundant nuclear non-histone chromosomal proteins that play a critical role in binding to distorted DNA structures and subsequently regulating DNA transcription, replication, repair, and recombination. Both HMGB1 and HMGB2 exhibit a high expression in several human cancers and are closely associated with tumor progression and a poor prognosis. However, the expression patterns of these molecules in pancreatic ductal adenocarcinoma (PDAC) remain to be elucidated.

Comparison of three Chlamydomonas strains which show distinctive oxidative stress tolerance.

Methyl viologen (MV) causes severe oxidative stress by generating superoxide in the photosystem. The marine Chlamydomonas strain W80 is highly tolerant to MV (inhibitory concentration 50% [IC₅₀]=110 μM), and another marine Chlamydomonas strain HS5 shows also relatively a high tolerance (IC₅₀=12 μM). These two marine strains and a freshwater Chlamydomonas reinhardtii, which is highly sensitive to MV (IC₅₀=0.

The contribution of Arabidopsis homologs of L-gulono-1,4-lactone oxidase to the biosynthesis of ascorbic acid.

To clarify the involvement of seven Arabidopsis homologs of rat L-gulono-1,4-lactone (L-GulL) oxidase, AtGulLOs, in the biosynthesis of L-ascorbic acid (AsA), transgenic tobacco cells overexpressing the various AtGulLOs were generated. Under treatment with L-GulL, the levels of total AsA in three transgenic tobacco cell lines, overexpressing AtGulLO2, 3, or 5, were significantly increased as compared with those in control cells.

Hydroperoxide reduction by thioredoxin-specific glutathione peroxidase isoenzymes of Arabidopsis thaliana.

Arabidopsis thaliana contains eight glutathione peroxidase (GPX) homologs (AtGPX1-8). Four mature GPX isoenzymes with different subcellular distributions, AtGPX1, -2, -5 and -6, were overexpressed in Escherichia coli and characterized. Interestingly, these recombinant proteins were able to reduce H2O2, cumene hydroperoxide, phosphatidylcholine and linoleic acid hydroperoxides using thioredoxin but not glutathione or NADPH as an electron donor.

Feedback inhibition of spinach L-galactose dehydrogenase by L-ascorbate.

We have studied the enzymological properties of L-galactose dehydrogenase (l-GalDH), a key enzyme in the biosynthetic pathway of l-ascorbate (AsA) in plants. L-GalDH was purified approximately 560-fold from spinach leaves. The enzyme was a homodimer with a subunit mass of 36 kDa.

Induction and functional analysis of two reduced nicotinamide adenine dinucleotide phosphate-dependent glutathione peroxidase-like proteins in Synechocystis PCC 6803 during the progression of oxidative stress.

Synechocystis PCC 6803 contains two types of glutathione peroxidase-like proteins (GPX-1 and GPX-2) that utilize NADPH but not reduced glutathione and unsaturated fatty acid hydroperoxides or alkyl hydroperoxides. The steady-state transcript level of gpx-1 gradually increased under oxidative stress conditions imposed by high light intensity, high salinity, or application of methylviologen or t-butyl hydroperoxide in the wild-type and GPX-2 knock-out mutant (gpx-2Delta) cells. To examine the ability of GPX-1, GPX-2, and thioredoxin peroxidase to scavenge lipid hydroperoxide in vivo, we measured the photosynthetic evolution of O(2) and the level of lipid peroxidation in the wild-type and each type of mutant cell after the application of t-butyl hydroperoxide or H(2)O(2).

Enhancement of stress tolerance in transgenic tobacco plants overexpressing Chlamydomonas glutathione peroxidase in chloroplasts or cytosol.

To evaluate the physiological potential of the defense system against hydroperoxidation of membrane-lipid components caused by environmental stresses in higher plants, we generated transgenic tobacco plants expressing a glutathione peroxidase (GPX)-like protein in the cytosol (TcGPX) or chloroplasts (TpGPX). The activities toward alpha-linolenic acid hydroperoxide in TcGPX and TpGPX plants were 47.5-75.

Molecular characterization of glutathione peroxidase-like protein in halotolerant Chlamydomonas sp. W80.

A cDNA clone encoding a glutathione peroxidase (GPX)-like protein was isolated from the cDNA library from halotolerant Chlamydomonas W80 (C. W80) by a simple screening method based on the bacterial expression system. The cDNA clone contained an open reading frame encoding a mature protein of 163 amino acids with a calculated molecular mass of 18 267 Da.

Thylakoid membrane-bound ascorbate peroxidase is a limiting factor of antioxidative systems under photo-oxidative stress.

To evaluate the physiological importance of thylakoid membrane-bound ascorbate peroxidase (tAPX) in the active oxygen species-scavenging system of chloroplasts, the level of tAPX in tobacco plants was altered by expression of the tAPX cDNA in both sense and antisense orientation. The tobacco plants transformed with constructs of antisense tAPXs from spinach and tobacco could not be obtained, suggesting that the suppression of tAPX in higher plants had a severe effect on the growth even under normal conditions. In contrast, the transgenic tobacco plants (TpTAP-12) overexpressing tAPX, which had approximately 37-fold higher activity than that of the wild-type plants, were generated.

Regulation and function of ascorbate peroxidase isoenzymes.

Even under optimal conditions, many metabolic processes, including the chloroplastic, mitochondrial, and plasma membrane-linked electron transport systems of higher plants, produce active oxygen species (AOS). Furthermore, the imposition of biotic and abiotic stress conditions can give rise to excess concentrations of AOS, resulting in oxidative damage at the cellular level. Therefore, antioxidants and antioxidant enzymes function to interrupt the cascades of uncontrolled oxidation in each organelle.

Crystallization and preliminary X-ray diffraction analysis of chloroplastic ascorbate peroxidase of tobacco plants.

The stromal ascorbate peroxidase of tobacco plants was crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 4000 as a precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 37.2, b = 76.