RESUMO
Seaweed produce antioxidants to counteract environmental stresses, and these antioxidant genes are regarded as important defense strategies for marine algae. In this study, the expression of Pyropia yezoensis (Bangiales, Rhodophyta) ascorbate peroxidase (PyAPX) and manganese-superoxide dismutase (PyMnSOD) was examined by qRT-PCR in P. yezoensis blades under abiotic stress conditions. Furthermore, the functional relevance of these genes was explored by overexpressing them in Chlamydomonas. A comparison of the different expression levels of PyAPX and PyMnSOD after exposure to each stress revealed that both genes were induced by high salt and UVB exposure, being increased approximately 3-fold after 12 h. The expression of the PyAPX and PyMnSOD genes also increased following exposure to H2O2. When these two genes were overexpressed in Chlamydomonas, the cells had a higher growth rate than control cells under conditions of hydrogen peroxide-induced oxidative stress, increased salinity, and UV exposure. These data suggest that Chlamydomonas is a suitable model for studying the function of stress genes, and that PyAPX and PyMnSOD genes are involved in the adaptation and defense against stresses that alter metabolism.
Assuntos
Ascorbato Peroxidases/metabolismo , Chlamydomonas/genética , Chlamydomonas/metabolismo , Rodófitas/genética , Rodófitas/metabolismo , Estresse Fisiológico , Superóxido Dismutase/metabolismo , Adaptação Fisiológica , Antioxidantes/metabolismo , Chlamydomonas/crescimento & desenvolvimento , Chlamydomonas/efeitos da radiação , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Peróxido de Hidrogênio/metabolismo , Estresse Oxidativo , Rodófitas/enzimologia , Salinidade , Superóxido Dismutase/genética , Transformação GenéticaRESUMO
Hymenobacter swuensis is a gamma-radiation resistant bacterium isolated from mountain soil in South Korea (N 35°51'38â³, E 127°44'47â³; altitude 1500m). The complete genome of H. swuensis consists of one chromosome (4,904,241bp) with three plasmids. The genomic sequence indicated that H. swuensis includes a series of genes involved in 2'-hydroxy-carotenoid biosynthesis. This is the first report describing the Hymenobacter genome and key enzymes in the 2'-hydroxy-carotenoid biosynthesis pathway. These data may provide opportunities for genetic engineering and antioxidant 2'-hydroxy-carotenoid production.
Assuntos
Cytophagaceae , Genoma Bacteriano/genética , Altitude , Carotenoides/metabolismo , Cytophagaceae/genética , Cytophagaceae/isolamento & purificação , Cytophagaceae/metabolismo , Cytophagaceae/fisiologia , Dados de Sequência Molecular , Radiação Ionizante , República da Coreia , Microbiologia do SoloRESUMO
In this study, thioredoxin h (Trxh) was isolated and characterized from the fresh water green alga Spirogyra varians, which was one amongst the pool of proteins induced upon gamma radiation treatment. cDNA clones encoding S. varians thioredoxin h were isolated from a pre-constructed S. varians cDNA library. Trxh had a molecular mass of 13.5kDa and contained the canonical WCGPC active site. Recombinant Trxh showed the disulfide reduction activity, and exhibited insulin reduction activity. Also, Trxh had higher 5,5'-dithiobis(2-nitrobenzoic acid) reduction activity with Arabidopsis thioredoxin reductase (TR) than with Escherichia coli TR. Specific expression of the Trxh gene was further analyzed at mRNA and protein levels and was found to increase by gamma irradiation upto the absorbed dose of 3kGy, suggesting that Trxh may have potential functions in protection of biomolecules from gamma irradiation.