Bertrand S.,University of Geneva |
Bertrand S.,CNRS Sea, Molecules and Health |
Bohni N.,University of Geneva |
Schnee S.,IPS Group |
And 3 more authors.
Biotechnology Advances | Year: 2014
Microorganisms have a long track record as important sources of novel bioactive natural products, particularly in the field of drug discovery. While microbes have been shown to biosynthesize a wide array of molecules, recent advances in genome sequencing have revealed that such organisms have the potential to yield even more structurally diverse secondary metabolites. Thus, many microbial gene clusters may be silent under standard laboratory growth conditions. In the last ten years, several methods have been developed to aid in the activation of these cryptic biosynthetic pathways. In addition to the techniques that demand prior knowledge of the genome sequences of the studied microorganisms, several genome sequence-independent tools have been developed. One of these approaches is microorganism co-culture, involving the cultivation of two or more microorganisms in the same confined environment. Microorganism co-culture is inspired by the natural microbe communities that are omnipresent in nature. Within these communities, microbes interact through signaling or defense molecules. Such compounds, produced dynamically, are of potential interest as new leads for drug discovery. Microorganism co-culture can be achieved in either solid or liquid media and has recently been used increasingly extensively to study natural interactions and discover new bioactive metabolites. Because of the complexity of microbial extracts, advanced analytical methods (e.g., mass spectrometry methods and metabolomics) are key for the successful detection and identification of co-culture-induced metabolites.This review focuses on co-culture studies that aim to increase the diversity of metabolites obtained from microbes. The various strategies are summarized with a special emphasis on the multiple methods of performing co-culture experiments. The analytical approaches for studying these interaction phenomena are discussed, and the chemical diversity and biological activity observed among the induced metabolites are described. © 2014 Elsevier Inc.
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.
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.
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.
Couteau C.,CNRS Sea, Molecules and Health |
Chauvet C.,University of Nantes |
Paparis E.,CNRS Sea, Molecules and Health |
Coiffard L.,CNRS Sea, Molecules and Health
PLoS ONE | Year: 2012
Background: To explain observed differences during SPF determination using either an in vivo or in vitro method, we hypothesized on the presence of ingredients having anti-inflammatory properties. Methodology/Principal Findings: To research our hypothesis, we studied the 21 UV filters both available on the market and authorized by European regulations and subjected these filters to the phorbol-myristate-acetate test using mice. We then catalogued the 13 filters demonstrating a significant anti-inflammatory effect with edema inhibition percentages of more than 70%. The filters are: diethylhexyl butamido triazone (92%), benzophenone-5 and titanium dioxide (90%), benzophenone-3 (83%), octocrylène and isoamyl p-methoxycinnamate (82%), PEG-25 PABA and homosalate (80%), octyl triazone and phenylbenzimidazole sulfonic acid (78%), octyl dimethyl PABA (75%), bis-ethylhexyloxyphenol methoxyphenyl triazine and diethylamino hydroxybenzoyl hexylbenzoate (70%). These filters were tested at various concentrations, including their maximum authorized dose. We detected a dose-response relationship. Conclusions/Significance: The anti-inflammatory effect of a sunscreen ingredient may affect the in vivo SPF value. © 2012 Couteau et al.
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).
Chenais B.,CNRS Sea, Molecules and Health |
Caruso A.,CNRS Sea, Molecules and Health |
Hiard S.,CNRS Sea, Molecules and Health |
Casse N.,CNRS Sea, Molecules and Health
Gene | Year: 2012
Transposable elements (TEs) are present in roughly all genomes. These mobile DNA sequences are able to invade genomes and their impact on genome evolution is substantial. The mobility of TEs can induce the appearance of deleterious mutations, gene disruption and chromosome rearrangements, but transposition activity also has positive aspects and the mutational activities of TEs contribute to the genetic diversity of organisms. This short review aims to give a brief overview of the impact TEs may have on animal and plant genome structure and expression, and the relationship between TEs and the stress response of organisms, including insecticide resistance. © 2012 Elsevier B.V.
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.
Chenais B.,CNRS Sea, Molecules and Health
Biochimica et Biophysica Acta - Reviews on Cancer | Year: 2013
Transposable elements are present in almost all genomes including that of humans. These mobile DNA sequences are capable of invading genomes and their impact on genome evolution is substantial as they contribute to the genetic diversity of organisms. The mobility of transposable elements can cause deleterious mutations, gene disruption and chromosome rearrangements that may lead to several pathologies including cancer. This mini-review aims to give a brief overview of the relationship that transposons and retrotransposons may have in the genetic cause of human cancer onset, or conversely creating protection against cancer. Finally, the cause of TE mobility may also be the cancer cell environment itself. © 2012 Elsevier B.V.
Couteau C.,CNRS Sea, Molecules and Health
Revue d'histoire de la pharmacie | Year: 2010
Human behavior towards the sun has changed over the years along with trends. Tan succeeded the white complexion. The sunscreens appeared recently in history. It is lining up with the discovery of bad effects due to prolonged exposure to ultraviolet at the end of the 19th century. Initially, those products had no signs of efficacy on their packaging, then the solar protection factors increased gradually, up to a limit value of 50+ more recently.