lunes, mayo 21, 2018

ATOPFe - NEW EXPERIMENTS ON Fe AND Cu BIOAVAILABILITY: NEW SCENARIOS IN THE FUTURE OCEANS BY M. MALDONADO


I have enjoyed tremendously my stay in the QUIMA lab of Profs. Magdalena Santana-Casiano and Melchor Gonzalez-Davila this April (2018). I have learnt so much from everyone! I send my warmest thank you to all members of the QUIMA lab, especially to Aridane Gonzalez and Carolina Santana Gonzalez, as well as Profs. Melchor Gonzalez and Magdalena Santana.  I have furthered my knowledge and experience with competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV), using the BASi Controlled Growth Mercury Electrodes (CGME) voltammeter. We have focused on measuring organic complexation of Cu, as well as designing and executing experiments to measure the kinetics of Fe and Cu adsorption to phytoplankton cell surfaces. With this work we aim to establish the density, kinetic constants and conditional stability constants of metal transporters specific for Cu and Fe at the cell surface of phytoplankton. This month, as a start, we used the diatoms, Phaeodactylum tricornutum and Thalassiosira oceanica as model phytoplankton. These diatoms have distinct strategies to acquire Cu and Fe, and respond physiologically different to Cu and/or Fe limitation (Maldonado and Price 2001; Allen et al. 2008; Shi et al. 2010; Lommer et al. 2012; Santana-Casiano et al. 2014; Guo et al. 2015; McQuaid et al. 2018).  We hope to determine how lowering dissolved Cu or Fe concentrations in seawater affect their cellular Cu and Fe transport and homeostasis mechanisms. Within the next year, we will also study the effects of ocean acidification on trace metal bioavailability. This work will elucidate what will control the bioavailability of Fe and Cu to marine phytoplankton in our oceans in the near future. This is part of the recently funded project to Profs. Santana-Casiano and Gonzalez-Davila, entitled “Effects of ocean acidification, temperature and organic matter on Fe(II) persistence in the Atlantic Ocean; ATOPFe”. This project is timely, as the newly established Global Ocean Acidification Observing Network (GOA-ON) aims to improve our understanding of a) the global ocean acidification conditions, as well as the ecosystem response to ocean acidification. In addition, this network aims to acquire and exchange the data and knowledge necessary to optimize the modeling of ocean acidification and its impacts.

High atmospheric CO2 levels are not only resulting in a warmer global climate, but are also profoundly changing the chemistry of our oceans. As the ocean absorbs ~30% of our anthropogenic CO2 emission, its surface waters are becoming more acidic.  The acidification of our oceans is expected to significantly affect trace metal bioavailability by changing a) the inorganic metal chemistry, b) the metal binding capacity of the organic ligands, and c) the kinetic parameters of trace metal transport in phytoplankton. So far, only a handful of studies have investigated the effects of ocean acidification on trace metal availability, focusing mainly on Fe. In collaboration, with Profs. Santana-Casiano and Gonzalez-Davila, we will examine the effects of ocean acidification on the concentration and speciation of the bioactive trace element Fe and Cu. We hypothesized that ocean acidification will decrease Fe availability and increase Cu toxicity to phytoplankton, which would ultimately result in a decrease in primary productivity in marine surface waters. As the pH decreases it is harder for the cell to eject the H+ they will send out at the same time as the electron that is reducing the organically bound Fe.




Major forms of Fe in seawater and depiction of a eukaryotic microalgal cell illustrating various Fe uptake mechanisms. From  A. Marchetti and M. T. Maldonado, “Iron” in “The Physiology of microalgae” by B. Borowitzka, M.A., Beardall, J. Raven J., Eds.; W.D.P. Stewart, California, 2016.


Proposed model of Cu acquisition & homeostasis in marine diatoms



Guo, J., B. Green, and M.T. Maldonado. 2015. Sequence Analysis and Gene Expression of Potential Components of Copper Transport and Homeostasis in Thalassiosira pseudonana. Protist 166: 58–77.



References cited


Allen, AE, et al. 2008. Whole-cell response of the pennate diatom Phaeodactylum tricornutum to iron starvation. Proceedings of the National Academy of Sciences 105 (30), 10438-10443

Lommer, M., et al. 2012. Genome and low-iron response of an oceanic diatom adapted to chronic iron limitation. Genome Biology 201213:R66

Maldonado, MT, NM Price. 2001. Reduction and transport of organically bound iron by Thalassiosira oceanica (Bacillariophyceae). Journal of Phycology 37 (2), 298-310

McQuaid, JB, et al 2018 Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms Nature 555 (7697), 534

Santana-Casiano, J.M., M. González-Dávila, A.G. González, M. Rico, A. López, A. Martel. 2014.
Characterization of phenolic exudates from Phaeodactylum tricornutum and their effects on the chemistry of Fe(II)–Fe(III). Marine Chemistry 158 (2014) 10–16.

Shi DXu YHopkinson BMMorel FM. 2010. Effect of ocean acidification on iron availability to marine phytoplankton. Science. 2010 : 327(5966):676-9




miércoles, mayo 16, 2018

QUIMA en EGU 2018


El pasado mes de Abril, entre los días 8 y 13, se celebró el congreso European Geosciences Union (EGU) en la ciudad de Viena. En este congreso el grupo QUIMA participó con el póster:TdFe(II) emissions in the degassing phase of Tagoro submarine volcano and its correlation with the decrease of pH elaborado por: Carolina Santana-González, J. Magdalena Santana-Casiano y Melchor González-Dávila.

Este trabajo fue presentado en la sesiónOcean, coastal and freshwater biogeochemistry, climate and ecosystems: recent advances and novel approaches to synthesis and predictions.

El resumen del trabajo está disponible en el siguiente link.



lunes, mayo 07, 2018

DRA. MALDONADO VISITA EL LABORATORIO DE QUIMA-IOCAG


Durante el mes de Abril, la Dra. M.T. Maldonado ha realizado una estancia en el laboratorio que nuestro grupo QUIMA tiene en las instalaciones del Instituto de Oceanografía y Cambio Global, IOCAG, de la ULPGC.

En este periodo hemos estado desarrollando una serie de experimentos pertenecientes al proyecto ATOPFe en el que la Dra. Maldonado es investigadora colaboradora.

La Dra. Maldonado es profesora en la Universidad British Columbia en Vancouver (Canadá) y en el siguiente enlace pueden ver su información:

Su experiencia se centra en los estudios de procesos fisiológicos de adquisición de metales traza esenciales por los microorganismos marinos. En el siguiente enlace pueden ver sus publicaciones.

La Dra. Maldonado es una investigadora de prestigio internacional y para nuestro equipo es un placer poder contar con ella para avanzar conjuntamente en estudios de metales traza, como el Fe y el Cu, y su interacción con microorganismos marinos. Las sinergias de los estudios entre los dos grupos de investigación contribuirán a mejorar el conocimiento de estos procesos en el medio marino.




martes, mayo 01, 2018

FRANÇOIS BURGAY, UNA VISITA PARA AMPLIAR HORIZONTES


Hace una semana, el investigador en formación François Burgay ha estado en nuestro laboratorio de QUIMA-IOCAG aprendiendo como realizamos estudios de oxidación y reducción de Fe a niveles subnanomolares con la técnica de la quimioluminiscencia. Esta visita es una forma de ampliar horizontes para que el investigador en formación pueda seguir con nuevas líneas en el futuro próximo. Desde el grupo QUIMA estamos muy contentos con su visita.

A continuación dejamos la carta de agradecimiento que nos hace llegar.

My name is François and I am a PhD student in Science and Management of Climate Change at the University Ca’ Foscari of Venice, Italy. My main interest of research is iron speciation in ice cores both performing absorption and chemiluminescence measurements. In particular, I want to see how dust fluxes have changed in the last millennia and to understand the impact of volcanoes on the Earth climate.

I am really thankful to Magdalena, Melchor and Carolina to have accepted my request to visit the labs in Gran Canaria. In the week I was here I performed some kinetic studies as a starting point for the future development of new analytical methods and to improve the set-up of the FeLume system I optimized in Venice.
It was an excellent, even if short, experience with great researchers. 

Thanks.