Draft genome sequence and genetic transformation of the oleaginous alga Nannochloropis gaditana

The potential use of algae in biofuels applications is receiving significant attention. However, none of the current algal model species are competitive production strains. Here we present a draft genome sequence and a genetic transformation method for the marine microalga Nannochloropsis gaditana CCMP526. We show that N. gaditana has highly favourable lipid yields, and is a promising production organism. The genome assembly includes nuclear (~29 Mb) and organellar genomes, and contains 9,052 gene models. We define the genes required for glycerolipid biogenesis and detail the differential regulation of genes during nitrogen-limited lipid biosynthesis. Phylogenomic analysis identifies genetic attributes of this organism, including unique stramenopile photosynthesis genes and gene expansions that may explain the distinguishing photoautotrophic phenotypes observed. The availability of a genome sequence and transformation methods will facilitate investigations into N. gaditana lipid biosynthesis and permit genetic engineering strategies to further improve this naturally productive alga

Major Cellular and Physiological Impacts of Ocean Acidification on a Reef Building Coral

As atmospheric levels of CO2 increase, reef-building corals are under greater stress from both increased sea surface temperatures and declining sea water pH. To date, most studies have focused on either coral bleaching due to warming oceans or declining calcification due to decreasing oceanic carbonate ion concentrations. Here, through the use of physiology measurements and cDNA microarrays, we show that changes in pH and ocean chemistry consistent with two scenarios put forward by the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, before affects on biomineralisation are apparent at the phenotype level. Under high CO2 conditions corals at the phenotype level lost over half their Symbiodinium populations, and had a decrease in both photosynthesis and respiration. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrate upregulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur before impacts on calcification

Pollution-induced community tolerance (PICT) as a tool for monitoring Lake Geneva long-term in situ ecotoxic restoration from herbicide contamination

Chemical monitoring revealed a regular decrease in herbicide concentration in Lake Geneva since last decades that may be linked to an ecotoxic restoration of nontarget phytoplanktonic communities. The Pollution-induced community tolerance (PICT) approach was tested as a tool to monitor the ecotoxic restoration of Lake Geneva for herbicides from 1999 to 2011. We conducted monthly assessments in 1999 and in 2011 for the tolerance of the phytoplankton communities to two herbicides (atrazine and copper), using PICT bioassays. The taxonomical composition of the communities was determined on the same collecting dates. The herbicide concentration decrease during the 12 years significantly influenced the composition of communities. The PICT monitoring indicated that a significant tolerance decrease in the community to both herbicides accompanied the herbicide concentration decrease. PICT measurements for atrazine and copper also changed at the intra-annual level. These variations were mainly due to community composition shifts linked to seasonal phosphorus and temperature changes. PICT monitoring on a seasonal basis is required to monitor the mean tolerance of communities. PICT appeared to be a powerful tool that reflected the toxic effects on environmental communities and to monitor ecotoxic ecosystem restoration