Levels of active oxygen species are controlled by ascorbic acid and anthocyanin in Arabidopsis

Stabilization of the levels of active oxygen species (AOS) is important to the survival of organisms. To clarify the system controlling levels of AOS in plants, this study used an electron spin resonance (ESR) method to directly measure superoxide radical (O(2)(.-)) scavenging activities in the wild-type Arabidopsis thaliana (Col and Ler ecotypes), two anthocyanin mutants (tt3 and ttg1), and an ascorbic acid mutant (vtc1). Under ordinary growth conditions, Arabidopsis contained superoxide-scavenging activity (SOSA) of approximately 300-500 SOD units/g of fresh weight. The ESR pattern indicated that most (40-50%) of this activity was due to ascorbic acid. For the analysis of SOSA under conditions of oxidative stress, synthesis of AOS was induced by gamma-irradiation. The radical scavenging activity in irradiated plants increased approximately 10-fold following an associated increase in the accumulation of ascorbic acid and anthocyanin. The accumulation of ascorbic acid and anthocyanin was suppressed by treatment with an antioxidant before irradiation and was induced by treatment with a radical-generating reagent. The contributions of ascorbic acid and anthocyanin to the total superoxide radical scavenging activity differed among ecotypes. In the Ler ecotype, ascorbic acid accumulated at twice the level of that in the Col ecotype, and induction of anthocyanin was half that in Col. To confirm the activity of ascorbic acid and anthocyanin against AOS stress, the viability of the wild type and mutants (tt2, tt3,tt5, ttg1, and vtc1) was examined after gamma-irradiation. Only the plants in which ascorbic acid and anthocyanin were induced had the ability to grow and flower.     

Characterization of the quantitatively major collagen in the mantle of oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis>

ABSTRACT:   A quantitatively major collagen was isolated from the pepsin-solubilized collagen preparation of the mantle by differential salt precipitation and phosphocellulose column chromatography, and its constituent α components (α1 and α2) were purified by phosphocellulose column chromatography. The subunits were demonstrated to be genetically distinct from each other by peptide mapping and amino acid analysis. The amino acid composition calculated from those of the α1 and α2 components in 2 : 1 ratio coincided well with that of the major collagen from the mantle. These results suggest that the major collagen in the mantle of the oyster may have a heterotrimer structure (α1)₂α2.     

Properties of scallop mantle collagen: its content,tissue distribution and thermal behavior

ABSTRACT:   To obtain fundamental information for the effective use of scallop Patinopecten yessoensis mantle, which is one of the underutilized marine resources. Some properties of collagen contained in the mantle were examined by chemical and histochemical techniques. Collagen content in the mantle varied annually, ranging from 0.98 to 1.72% of wet tissue, 7.7 to 12.6% of dry tissue and 13.5 to 26.5% of total protein, being relatively in high level of collagen content of invertebrate muscles. Collagen fiber was densely distributed in the inner connective tissue matrix of the mantle pallial, in contrast to the inner fold part which was rich in muscle fibers. The collagen contained in the crude collagen fraction (residue after alkali extraction), prepared from the mantle, was revealed to have considerably low solubility on hot-water extraction, constantly less than 20% of the total collagen at the temperatures in the range of 20–90°C.     

Gene response in rice plants treated with continuous fog influenced by pH,was similar to that treated with biotic stress

Background

Throughout Asia, including Japan, rice plants are cultivated in a wide range of areas from lowlands to highlands and are frequently exposed to fog, including acid fog. Some physiological studies have shown that acid fog can be a stress factor for plants. We analyzed the gene expression profiles of rice plants treated with artificially prepared simulated acid fog (SiAF) or simulated neutral fog (SiNF) for 1 or 7 days.

Results

Microarray analysis results suggested that both the SiAF and the SiNF treatments induced the expression of genes involved in the defense and stress responses in rice plants. Induction of such genes was detected in plants treated with SiAF for 1 day, and the number of induced genes increased in plants treated with SiAF for 7 days. The genes for defense and stress responses were also induced by SiNF for 7 days, although they were not induced by SiNF for 1 day. The gene expression profiles of the SiAF-treated and the SiNF-treated plants were compared to those of plants treated with other stress factors. The comparison revealed that both SiAF and SiNF treatments have similar effects to biotic stresses and ozone stress. The genes encoding NADPH oxidase and germin, which function in apoplasts, were also induced by SiAF, SiNF and biotic stresses.

Conclusions

These findings suggest that both the SiAF and the SiNF treatments may result in oxidative stress through the apoplastic production of reactive oxygen species.     

Molecular species of collagen in muscular and vertebral parts of white sturgeon Acipenser transmontanus

The molecular species of collagen in the muscular and vertebral parts of white sturgeon Acipenser transmontanus were examined by biochemical techniques. Pepsin-solubilized collagens were prepared from these parts, and fractionated into major and minor collagen fractions by differential salt precipitation at acidic or neutral pH. Collagens contained in these fractions showed several features characteristic of fish type I and V collagens, respectively, in SDS-PAGE patterns and the amino acid compositions of both parts. These results suggest that at least two molecular species, corresponding to type I and V collagens, are distributed in the muscular and vertebral parts of white sturgeon.     

cDNA cloning of Japanese oyster stress protein homologous to the mammalian 78-kDa glucose regulated protein and its induction by heatshock

ABSTRACT:    The 78-kDa glucose regulated protein (GRP78), a member of stress proteins, was cloned from a cDNA library of Japanese oyster Crassostrea gigas . The analysis on Japanese oyster GRP78 clone of approximately 2.6 kb revealed that the entire open reading frame was 1983 bp long and encoded 661 amino acid residues. At the DNA sequence level, the coding region of Japanese oyster GRP78 gene was 72, 62, and 62% identical to those of chicken GRP78, Japanese flounder HSP70, and Japanese flounder HSC71 genes, respectively. Deduced amino acid sequence of Japanese oyster GRP78 was 84, 62, and 62% identical to those of chicken GRP78, Japanese flounder HSP70, and Japanese flounder HSC71, respectively. Japanese oyster GRP78 contained an 18-residue sequence at the N-terminus that exhibits characteristics of a cleavable signal sequence. It also contained an ATPase domain, and a peptide-binding domain in addition to a Lys-Asp-Glu-Leu (KDEL) peptide motif that is involved in determining endoplasmic reticulum localization. Northern blot analysis showed that GRP78 mRNA was induced with heatshock treatment in the oyster tissues.