Identification of Copper-Induced Genes in the Marine Alga Ulva compressa (Chlorophyta)

Abstract

In order to identify genes/proteins involved in copper tolerance, the marine alga Ulva compressa was cultivated with 10 μM copper for 3 days. The activities of antioxidant enzymes ascorbate peroxidase (AP), peroxiredoxin (PRX), thioredoxin (TRX), and glutathione-S-transferase (GST) and the level of lipoperoxides were determined in the alga cultivated with and without copper addition. Antioxidant enzyme activities and lipoperoxides level increased in response to copper excess, indicating that the alga was under oxidative stress. A cDNA library was prepared using U. compressa cultivated with 10 μM copper for 3 days. A total of 3 × 10(4) clones were isolated and 480 clones were sequenced, resulting in 235 non-redundant ESTs, of which 104 encode proteins with known functions. Among them, we identified proteins involved in (1) antioxidant metabolism such as AP, PRX, TRX, GST, and metalothionein (MET), (2) signal transduction, such as calmodulin (CAM), (3) calcium-dependent protein kinase (CDPK) and nucleoside diphosphate kinase (NDK), (4) gene expression, (5) protein synthesis and degradation, and (6) chloroplast and mitochondria electron transport chains. Half of the identified proteins are potentially localized in organelles. The relative level of 18 genes, including those coding for AP, PRX, TRX, GST, MET, CAM, CDPK, and NDK were determined by quantitative RT-PCR in the alga cultivated with 10 μM copper for 0 to 7 days. Transcript levels increased in response to copper stress and most of them reached a maximum at days 3 and 5. Thus, the selected genes are induced by copper stress and they are probably involved in copper acclimation and tolerance.

Copper-induced overexpression of genes encoding antioxidant system enzymes and metallothioneins involve the activation of CaMs, CDPKs and MEK1/2 in the marine alga Ulva compressa

“…Furthermore, a cDNA library was prepared with the alga cultivated with 10 µM copper for 3 days, which allowed the identification of a sequence encoding AP, and a MT with homology the oyster Crassostrea virginica MT; these genes were overexpressed in response to 10 µM copper with a maximal level at day 3 (Contreras-Porcia et al 2011). On the other hand, a MT was isolated from the marine brown alga Fucus vesiculosus showing homology to invertebrate MTs and its expression was also induced by copper excess (Morris et al 1999).…”

Differential gene expression in Pyropia columbina (Bangiales, Rhodophyta) under natural hydration and desiccation conditions

“…Readings from both libraries were processed by selfwritten Perl scripts and assembled into coatings, i.e., representing putative transcripts using MIRA 3 assembly (Contreras-Porcia et al, 2011b). The expressed sequences tags (ESTs) determined from both libraries were subjected to separated bioinformatics analyses.…”

Proteomics in Seaweeds: Ecological Interpretations

“…For example, the distribution of macroalgal species at the upper limit of the rocky intertidal zone is principally determined by abiotic factors such as UV radiation, light, salinity, temperature changes, nutrient availability and desiccation (e.g. Aguilera et al, 2002;Burritt et al, 2002;Cabello-Pasini et al, 2000;Contreras-Porcia et al, 2011a;Véliz et al, 2006). On the other hand, the microalgae diversity is maintained by a combination of variable forces -environmental oscillations (e.g.…”

“…In macro and micro-algae it is possible to determine that under natural abiotic factors, a common cellular response could involve the over-production of reactive oxygen species (ROS) (Andrade et al, 2006;Contreras et al, 2005Contreras et al, , 2007bContreras et al, , 2009Contreras-Porcia et al, 2011a;Kumar et al, 2010;Lee & Shin, 2003;Liu et al, 2007;Rijstenbil, 2001). ROS are ubiquitous byproducts of oxidative metabolism that are also involved in intracellular signalling processes (e g. Blokhina & Fagerstedt, 2010;Rhee, 2006).…”