Photosynthetic gene expression responses of the oceanic ubiquitous cyanobacterium Prochlorococcus due to changes of environmental variables

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainThe cyanobacterium Prochlorococcus is the smallest and most abundant photosynthetic organism on Earth [1]. Being a main global primary producer and ubiquist in the tropical and subtropical regions of the world’s oceans [2], it constitutes a good sentinel species for evaluating the effect of environmental stressors on oceanic photosynthesis. We developed a sensitive method to monitor the expression of two genes responsible of photosynthesis in Prochlorococcus, rbcL (RuBisCO) and psbA (D1 protein), using rnpB as reference gene [3,4]. We applied the method to samples from 63 stations of the Malaspina circumnavigation cruise (December 2010 - July 2011), sampled at three depths. In addition, natural communities of nano-and picoplankton were experimentally exposed to organic pollutant mixtures. Expression of Prochlorococcus rbcL and psbA genes correlated with several physical variables and other biological measurements, and were sensitive to low levels of organic pollutant mixtures. We consider these sublethal effects on the photosynthesis, together with already known effects at cellular level [5,6], are significant potential perturbators of the oceanic carbon cycle. This confirms the anthropogenic chemosphere as a vector of global change during the Anthropocene. 1. Bryant DA 2003 Proc Natl Acad Sci USA 100:9647-9649 2. Partensky F et al. 1999 Microbiol Mol Biol Rev 63:106-127 3. Martiny AC et al. 2006 Proc Natl Acad Sci USA 103:12552-12557 4. Gomez-Baena G et al 2009 Res Microbiol 160:567-575 5. Echeveste P et al. 2010 Chemosphere 81:161-168 6. Echeveste P et al. 2011 Environ Pollut 159:1307-1316Peer Reviewe

Effects of organic pollutants on oceanic photosynthetic function mediated by Prochlorococcus

Society of Environmental Toxicology and Chemistry (SETAC) Europe 25th Annual Meeting, 3-7 May 2015, Barcelona.-- 2 pages, 4 figuresProchlorococcus is the smallest and most abundant photosynthetic organism known on Earth and a major contributor of ocenic primary production. This cianobacterium is ubiquist in every ocean from 40°N to 40°S, from surface to 200 m depth in the water column, reaching abundances close to 10 cells/mL worldwide [1]. Its large surface/volume ratio gives it a high efficiency for light and nutrients capture. On the other hand, this characteristics also implicate a higher intake and a faster bioconcentration of pollutants, resulting in an extreme sensitivity to a variety of environmental stressors, from UV radiation to organic pollutants [2]. Therefore, Prochlorococcus constitutes an excellent sentinel organism to evaluate the dependence of the photosynthetic function to environmental variables and anthropogenic impacts in middle latitudinal oceans. Over the past century the global phytoplankton concentration has declined and changes in chlorophyll and primary production have been detected, which has been attributed to the impact of global climate change [3]. Global Change is a set of interlinked vectors, being one of the best studied the climate change. Neverthelees, the only vector whose global impact has not been quantifyed yet is chemical pollution [4]. In this way, the main objective of the present work was to measure the photosynthetic capacity of Prochlorococcus in Atlantic, Indian and Pacific oceans during the Malaspina circumnavigation, and study its relationship with the concentrations of diverse organic pollutants. This study was performed within a framework of more than 300 biological, physical and chemical variables, using both field sample collection and experiments on board with wild communitiesThis work was funded by the Spanish Government through the Malaspina project. MC Fernández-Pinos acknowledges a predoctoral fellowship from the Spanish National Research CouncilPeer Reviewe

Fluorescent Nucleoside Derivatives as a Tool for the Detection of Concentrative Nucleoside Transporter Activity Using Confocal Microscopy and Flow Cytometry

The abundance and function of transporter proteins at the plasma membrane are likely to be crucial in drug responsiveness. Functional detection of human concentrative nucleoside transporters (hCNTs) is of interest for predicting drug sensitivity because of their ability to transport most nucleoside-derived drugs. In the present study, two fluorescent nucleoside analogues, uridine-furan and etheno-cytidine, were evaluated as tools to study <i>in vivo</i> nucleoside transporter-related functions. These two molecules showed high affinity interactions with hCNT1 and hCNT3 and were shown to be substrates of both transporters. Both fluorescence microscopy and flow cytometry experiments showed that uridine-furan uptake was better suited for distinguishing cells that express hCNT1 or hCNT3. These data highlight the usefulness of fluorescent nucleoside derivatives, as long as they fulfill the requirements of confocal microscopy and flow cytometry, for <i>in vivo</i> analysis of hCNT-related function