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Pfeil B.E.,Gothenburg University | Schoefs B.,CNRS Sea, Molecules and Health | Spetea C.,Gothenburg University
Cellular and Molecular Life Sciences | Year: 2014

Chloroplasts from land plants and algae originated from an endosymbiotic event, most likely involving an ancestral photoautotrophic prokaryote related to cyanobacteria. Both chloroplasts and cyanobacteria have thylakoid membranes, harboring pigment-protein complexes that perform the light-dependent reactions of oxygenic photosynthesis. The composition, function and regulation of these complexes have thus far been the major topics in thylakoid membrane research. For many decades, we have also accumulated biochemical and electrophysiological evidence for the existence of solute transthylakoid transport activities that affect photosynthesis. However, research dedicated to molecular identification of the responsible proteins has only recently emerged with the explosion of genomic information. Here we review the current knowledge about channels and transporters from the thylakoid membrane of Arabidopsis thaliana and of the cyanobacterium Synechocystis sp. PCC 6803. No homologues of these proteins have been characterized in algae, although similar sequences could be recognized in many of the available sequenced genomes. Based on phylogenetic analyses, we hypothesize a host origin for most of the so far identified Arabidopsis thylakoid channels and transporters. Additionally, the shift from a non-thylakoid to a thylakoid location appears to have occurred at different times for different transport proteins. We propose that closer control of and provision for the thylakoid by products of the host genome has been an ongoing process, rather than a one-step event. Some of the proteins recruited to serve in the thylakoid may have been the result of the increased specialization of its pigment-protein composition and organization in green plants. © 2013 The Author(s). Source

Chenais B.,CNRS Sea, Molecules and Health
Current Cancer Drug Targets | Year: 2015

Transposable elements (TEs) are mobile DNA sequences representing a substantial fraction of most genomes. Through the creation of new genes and functions, TEs are important elements of genome plasticity and evolution. However TE insertion in human genomes may be the cause of genetic dysfunction and alteration of gene expression contributing to cancer and other human diseases. Besides the chromosome rearrangements induced by TE repeats, this mini-review shows how gene expression may be altered following TE insertion, for example by the creation of new polyadenylation sites, by the creation of new exons (exonization), by exon skipping and by other modification of alternative splicing, and also by the alteration of regulatory sequences. hrough the I correlation between TE mobility and the methylation status of DNA, the importance of chromatin regulation is evident in several diseases. Finally this overview ends with a brief presentation of the use of TEs as biotechnology tools for insertional mutagenesis screening and gene therapy with DNA transposons. © 2015 Bentham Science Publishers. Source

Pruvost J.,University of Nantes | Van Vooren G.,University of Nantes | Le Gouic B.,University of Nantes | Couzinet-Mossion A.,CNRS Sea, Molecules and Health | Legrand J.,University of Nantes
Bioresource Technology | Year: 2011

We describe a methodology to investigate the potential of given microalgae species for biodiesel production by characterizing their productivity in terms of both biomass and lipids. A multi-step approach was used: determination of biological needs for macronutrients (nitrate, phosphate and sulphate), determination of maximum biomass productivity (the " light-limited" regime), scaling-up of biomass production in photobioreactors, including a theoretical framework to predict corresponding productivities, and investigation of how nitrate starvation protocol affects cell biochemical composition and triggers triacylglycerol (TAG) accumulation. The methodology was applied to two freshwater strains, Chlorella vulgaris and Neochloris oleoabundans, and one seawater diatom strain, Cylindrotheca closterium. The highest total lipid content was achieved with N. oleoabundans (25-37% of DW), while the highest TAG content was found in C. vulgaris (11-14% of DW). These two species showed similar TAG productivities. © 2010 Elsevier Ltd. Source

Laviale M.,CNRS Sea, Molecules and Health | Neveux J.,University Pierre and Marie Curie
Marine Ecology Progress Series | Year: 2011

Light-dependent variation in pigment content was examined in 11 marine phytoplankton species representing 8 algal classes. Batch cultures of each species were acclimated to 7 irradiances between 10 and 700 μmol photons m-2 s-1. High-performance liquid chromatography analysis on exponentially growing cultures revealed that pigment ratios normalised to chlorophyll a (chl a) generally fell within the ranges previously reported for species of the same taxa. Unambiguous lightharvesting pigments (e.g. chlorophylls, fucoxanthin) showed limited amplitude of variation between low and high light conditions, while those involved in photoprotection (e.g. zeaxanthin, lutein, alloxanthin, diatoxanthin) dramatically increased under high light. Most of the relationships between pigment:chl a ratios and growth irradiance were quite well described using simple linear models. Among pigments shared by several species, chl b and c3, fucoxanthin, zeaxanthin, lutein, diadinoxanthin and diatoxanthin exhibited similar trends regardless of the species studied, allowing general equations to be determined for each of these pigments. Determination of light:pigment relationships is a prerequisite for the development of more advanced modeling techniques such as artificial neural networks in chemotaxonomic studies. © Inter-Research 2011. Source

Kazemipour F.,CNRS Nantes Laboratory of Planetology and Geodynamics | Launeau P.,CNRS Nantes Laboratory of Planetology and Geodynamics | Meleder V.,CNRS Sea, Molecules and Health
Remote Sensing of Environment | Year: 2012

A new fast mapping approach based on an optical model was developed and applied to hyperspectral airborne HySpex images of Bourgneuf Bay (French Atlantic coast). The aims were (1) to discriminate diatom biofilms (from the Bacillariophyceae class) constituting microphytobenthos on any mudflat and (2) to estimate their biomass expressed in mgChla.m -2 by remote sensing of poorly accessible mudflats.Due to the distinct absorption peaks of certain pigments of different microalgae classes constituting microphytobenthos, the high spectral resolution of hyperspectral images was employed in order to detect the pigment assemblage characterizing diatom biofilms. Thus, the HySpex 1600 VNIR camera was used both in the laboratory for estimating biomass under controlled conditions and in an airborne setting. 1) The mapping approach used known spectral indices (NDVI and MPBI) and new ones (I Diatom and I Euglenid) to characterize quickly the key pigments of two main microphytobenthos classes, for a fast selection of diatom and euglenid biofilms by two different masks. 2) The inherent spectral properties of biofilms in the 700-900nm range were also used to calculate an original estimate of the substrate/environmental effects in each mask. 3) Biomass quantification of the diatom biofilms was finally performed by application of the microphytobenthos optical model (MPBOM).This approach was first tested on laboratory HySpex images of synthetic biofilms for which the in vitro biomass measurements by chromatography (HPLC) were available. The comparison between estimated and measured biomass values showed the reliability of the mapping approach for biomass estimation. Finally, a map of diatom biomass was obtained at the scale of the entire Bourgneuf Bay. The range of biomass variation (0-35mgChla.m -2) was in close agreement with the biomass maps presented in previous studies. © 2012 Elsevier Inc. Source

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