RESUMEN
BACKGROUND: Non-photosynthetic chlorophyll (Chl) proteins called water-soluble Chl-binding proteins are distributed in Brassicaceae plants. Brassica oleracea WSCP (BoWSCP) and Lepidium virginicum WSCP (LvWSCP) are highly expressed in leaves and stems, while Arabidopsis thaliana WSCP (AtWSCP) and Raphanus sativus WSCP (RshWSCP) are highly transcribed in floral organs. BoWSCP and LvWSCP exist in the endoplasmic reticulum (ER) body. However, the subcellular localization of AtWSCP and RshWSCP is still unclear. To determine the subcellular localization of these WSCPs, we constructed transgenic plants expressing Venus-fused AtWSCP or RshWSCP. RESULTS: Open reading frames corresponding to full-length AtWSCP and RshWSCP were cloned and ligated between the cauliflower mosaic virus 35S promoter and Venus, a gene encoding a yellow fluorescent protein. We introduced the constructs into A. thaliana by the floral dip method. We succeeded in constructing a number of transformants expressing Venus-fused chimeric AtWSCP (AtWSCP::Venus) or RshWSCP (RshWSCP::Venus). We detected fluorescence derived from the chimeric proteins using a fluorescence microscope system. In cotyledons, fluorescence derived from AtWSCP::Venus and RshWSCP::Venus was detected in spindle structures. The spindle structures altered their shape to a globular form under blue light excitation. In true leaves, the number of spindle structures was drastically reduced. These observations indicate that the spindle structure was the ER body. CONCLUSIONS: AtWSCP and RshWSCP have the potential for ER body targeting like BoWSCP and LvWSCP.
Asunto(s)
Arabidopsis/genética , Proteínas de Unión a Clorofila/genética , Cotiledón/genética , Retículo Endoplásmico/genética , Regulación de la Expresión Génica de las Plantas , Raphanus/genética , Arabidopsis/metabolismo , Arabidopsis/ultraestructura , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Caulimovirus/genética , Caulimovirus/metabolismo , Clorofila/metabolismo , Proteínas de Unión a Clorofila/metabolismo , Cotiledón/metabolismo , Cotiledón/ultraestructura , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/ultraestructura , Genes Reporteros , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Plantas Modificadas Genéticamente/ultraestructura , Regiones Promotoras Genéticas , Unión Proteica , Raphanus/metabolismo , Raphanus/ultraestructura , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Huso Acromático/genética , Huso Acromático/metabolismo , Huso Acromático/ultraestructuraRESUMEN
Twenty-five days after the disaster at the Fukushima Daiichi nuclear power plant in 2011, we collected samples of the green macroalga Bryopsis maxima from the Pacific coast of Japan. Bryopsis maxima is a unicellular, multinuclear, siphonous green macroalga. Radiation analysis revealed that B. maxima emitted remarkably high gamma radiation of (131)I, (134)Cs, (137)Cs, and (140)Ba as fission products of (235)U. Interestingly, B. maxima contained naturally occurring radionuclides derived from (226)Ra and (228)Ra. Analysis of element content revealed that B. maxima accumulates many ocean elements, especially high quantities of the alkaline earth metals Sr (15.9 g per dry-kg) and Ba (3.79 g per dry-kg), whereas Ca content (12.5 g per dry-kg) was lower than that of Sr and only 61 % of the mean content of 70 Japanese seaweed species. Time-course analysis determined the rate of radioactive (85)Sr incorporation into thalli to be approximately 0.13 g Sr per dry-kg of thallus per day. Subcellular fractionation of B. maxima cells showed that most of the (85)Sr was localized in the soluble fraction, predominantly in the vacuole or cytosol. Given that (85)Sr radioactivity was permeable through a dialysis membrane, the (85)Sr was considered to be a form of inorganic ion and/or bound with a small molecule. Precipitation analysis with sodium sulfate showed that more than 70% of the Sr did not precipitate as SrSO4, indicating that a proportion of the Sr may bind with small molecules in B. maxima.
