Interactions between marine picoeukaryotes and their viruses one cell at a time = Interacciones entre picoeucariotas marinos y sus virus célula a célula

[eng] Marine viruses are key components of marine microbial communities, as they influence the cellular abundances and the community structure of microbes, participate in their genetic exchange, and intervene in the ocean biogeochemical cycles. Most studies dealing with the role of viruses in the marine environment have been done from a bulk community point of view, but going from the bulk community perspective to specific virus─host relationships is essential in order to understand the role of viruses in shaping a determined host community, in modifying host genomes, and ultimately in the release of organic compounds from the lysed cells. For this reason, in this thesis we implemented and applied different methodologies that are able to detect, visualize and quantify virus─host interactions in marine eukaryotes at the single cell level. We focused on picoeukaryotes (cells <3 µm) because they play crucial roles in marine food webs and biogeochemical cycles, and virus─host interactions in natural populations of these minute eukaryotes are largely unknown. In the first chapter we combined previously developed techniques, used to assess prokaryotic host─phage interactions, to implement VirusFISH for detecting specific virus─host dynamics, using as a model system the photosynthetic picoeukaryote Ostreoccocus tauri and its virus OtV5. With the VirusFISH technique, we could also monitor the infection, as well as quantify the free viruses produced during the lysis of the host in a non-axenic culture, which allowed the calculation of the burst size. This study set the ground for the application of the VirusFISH technique to natural samples. In the second chapter of this thesis, we applied VirusFISH to seawater samples from the Bay of Biscay (Cantabrian Sea) to study the dynamics of viral infection in natural populations of Ostreococcus along a seasonal cycle. We were able to quantify the percentage of cells infected over time, and compared these results with the transcriptional viral and host activities derived from metatranscriptomic data. This constitutes the first study where a specific viral─host interaction has been visualized and monitored over time in a natural system. Picoeukaryotes in the ocean are prevalently uncultured, and thus, in the third chapter of this thesis we went an step further to unveil novel viral─host relationships in eukaryotic uncultured hosts. For this purpose, we mined single amplified genomes (SAGs) of picoeukaryotes obtained during the Tara Oceans expedition for viral signatures. We found that almost 60% of the cells analyzed presented an associated virus with narrow host specificity. Some of the viral sequences were widely distributed and some geographically constrained, and they were preferentially found at the deep chlorophyll maximum. Moreover, we found a mavirus virophage potentially integrated in four SAGs of two different lineages, suggesting the presence of virophages is more common than previously thought. In summary, in this thesis we have implemented and used techniques that allow us to detect and monitor specific virus─host interactions, which is one of the major challenges in marine viral ecology. On the one hand, VirusFISH arises as a powerful technique that can be easily adapted to any host─virus system that has been genome-sequenced. On the other hand, the results obtained with the single cell genomics offer the opportunity to formulate hypothesis based on detected viral─host interactions in uncultured prevalent marine picoeukaryotes, which can be later tested using experimental approaches.[spa] Se han realizado muchos estudios sobre el rol de los virus en ambientes marinos desde el punto de vista de comunidad global, pero es esencial que vayamos hacía una visión más específica de relación virus─hospedador. Por ello, en esta tesis implementamos y aplicamos diferentes metodologías para estudiar interacciones virus─hospedador, centrándonos en picoeucariotas marinos ya que se conoce muy poco de ellos en poblaciones naturales. En el primer capítulo implementamos la técnica VirusFISH, permitiendo detectar dinámicas específicas virus─hospedador eucarióticos, usando como modelo Ostreococcus tauri y su virus OtV5. VirusFISH permitió monitorizar la infección, cuantificar en un cultivo no axénico los virus libres producidos durante la lisis y calcular el tamaño de explosión. Este estudio estableció la base para la aplicación de VirusFISH en muestras naturales. En el segundo capítulo aplicamos VirusFISH en muestras de agua natural para estudiar las dinámicas de infección en Ostreococcus. Cuantificamos el porcentaje de células infectadas durante un ciclo estacional y lo comparamos con las actividades transcripcionales de virus y Ostreococcus spp. Este constituye el primer estudio donde se visualiza y monitoriza una interacción específica virus─hospedador en el tiempo en un sistema natural. En el tercer capítulo descubrimos nuevas relaciones virus─hospedador en células no cultivadas, analizando genomas amplificados individuales de picoeucariotas, encontrando que la mayoría de las células presentaron al menos un virus. Estas secuencias víricas se encontraron preferentemente en el máximo profundo de clorofila, algunas de ellas ampliamente distribuidas por los océanos y otras constreñidas geográficamente. Además, encontramos un virofago mavirus potencialmente integrado en dos linajes distintos, sugiriendo que los virofagos son más comunes de lo que se pensaba. En resumen, hemos implementado y usado técnicas que nos han permitido detectar y monitorizar interacciones específicas virus─hospedador, uno de los mayores retos en la ecología microbiana marina. Por un lado, VirusFISH surge como una técnica potente que puede ser fácilmente adaptada a cualquier sistema virus─hospedador del cual tengamos el genoma secuenciado. Por otro lado, los resultados obtenidos con la genómica de célula individual muestran la oportunidad de formular hipótesis basadas en interacciones virus─hospedador detectadas en picoeucariotas marinos no cultivados, que pueden ser posteriormente testadas mediante aproximaciones experimentales

Viruses and Protists Induced-mortality of Prokaryotes around the Antarctic Peninsula during the Austral Summer

During the Austral summer 2009 we studied three areas surrounding the Antarctic Peninsula: the Bellingshausen Sea, the Bransfield Strait and the Weddell Sea. We aimed to investigate, whether viruses or protists were the main agents inducing prokaryotic mortality rates, and the sensitivity to temperature of prokaryotic heterotrophic production and mortality based on the activation energy (Ea) for each process. Seawater samples were taken at seven depths (0.1–100 m) to quantify viruses, prokaryotes and protists abundances, and heterotrophic prokaryotic production (PHP). Viral lytic production, lysogeny, and mortality rates of prokaryotes due to viruses and protists were estimated at surface (0.1–1 m) and at the Deep Fluorescence Maximum (DFM, 12–55 m) at eight representative stations of the three areas. The average viral lytic production ranged from 1.0 ± 0.3 × 107 viruses ml−1 d−1 in the Bellingshausen Sea to1.3 ± 0.7 × 107 viruses ml−1 d−1 in the Bransfield Strait, while lysogeny, when detectable, recorded the lowest value in the Bellingshausen Sea (0.05 ± 0.05 × 107 viruses ml−1 d−1) and the highest in the Weddell Sea (4.3 ± 3.5 × 107 viruses ml−1 d−1). Average mortality rates due to viruses ranged from 9.7 ± 6.1 × 104 cells ml−1 d−1 in the Weddell Sea to 14.3 ± 4.0 × 104 cells ml−1 d−1 in the Bellingshausen Sea, and were higher than averaged grazing rates in the Weddell Sea (5.9 ± 1.1 × 104 cells ml−1 d−1) and in the Bellingshausen Sea (6.8 ± 0.9 × 104 cells ml−1 d−1). The highest impact on prokaryotes by viruses and main differences between viral and protists activities were observed in surface samples: 17.8 ± 6.8 × 104 cells ml−1 d−1 and 6.5 ± 3.9 × 104 cells ml−1 d−1 in the Weddell Sea; 22.1 ± 9.6 × 104 cells ml−1 d−1 and 11.6 ± 1.4 × 104 cells ml−1 d−1 in the Bransfield Strait; and 16.1 ± 5.7 × 104 cells ml−1 d−1 and 7.9 ± 2.6 × 104 cells ml−1 d−1 in the Bellingshausen Sea, respectively. Furthermore, the rate of lysed cells and PHP showed higher sensitivity to temperature than grazing rates by protists. We conclude that viruses were more important mortality agents than protists mainly in surface waters and that viral activity has a higher sensitivity to temperature than grazing rates. This suggests a reduction of the carbon transferred through the microbial food-web that could have implications in the biogeochemical cycles in a future warmer ocean scenario.En prens

Assessing Viral Abundance and Community Composition in Four Contrasting Regions of the Southern Ocean

We explored how changes of viral abundance and community composition among four contrasting regions in the Southern Ocean relied on physicochemical and microbiological traits. During January–February 2015, we visited areas north and south of the South Orkney Islands (NSO and SSO) characterized by low temperature and salinity and high inorganic nutrient concentration, north of South Georgia Island (NSG) and west of Anvers Island (WA), which have relatively higher temperatures and lower inorganic nutrient concentrations. Surface viral abundance (VA) was highest in NSG (21.50 ± 10.70 × 106 viruses mL−1) and lowest in SSO (2.96 ± 1.48 × 106 viruses mL−1). VA was positively correlated with temperature, prokaryote abundance and prokaryotic heterotrophic production, chlorophyll a, diatoms, haptophytes, fluorescent organic matter, and isoprene concentration, and was negatively correlated with inorganic nutrients (NO3−, SiO42−, PO43−), and dimethyl sulfide (DMS) concentrations. Viral communities determined by randomly amplified polymorphic DNA–polymerase chain reaction (RAPD-PCR) were grouped according to the sampling location, being more similar within them than among regions. The first two axes of a canonical correspondence analysis, including physicochemical (temperature, salinity, inorganic nutrients—NO3−, SiO42−, and dimethyl sulfoniopropionate -DMSP- and isoprene concentrations) and microbiological (chlorophyll a, haptophytes and diatom, and prokaryote abundance and prokaryotic heterotrophic production) factors accounted for 62.9% of the variance. The first axis, temperature-related, accounted for 33.8%; the second one, salinity-related, accounted for 29.1%. Thus, different environmental situations likely select different hosts for viruses, leading to distinct viral communities.En prens

Changes in Liver Lipidomic Profile in G2019S- LRRK2 Mouse Model of Parkinson's Disease

15 páginas, 4 figurasThe identification of Parkinson's disease (PD) biomarkers has become a main goal for the diagnosis of this neurodegenerative disorder. PD has not only been intrinsically related to neurological problems, but also to a series of alterations in peripheral metabolism. The purpose of this study was to identify metabolic changes in the liver in mouse models of PD with the scope of finding new peripheral biomarkers for PD diagnosis. To achieve this goal, we used mass spectrometry technology to determine the complete metabolomic profile of liver and striatal tissue samples from WT mice, 6-hydroxydopamine-treated mice (idiopathic model) and mice affected by the G2019S-LRRK2 mutation in LRRK2/PARK8 gene (genetic model). This analysis revealed that the metabolism of carbohydrates, nucleotides and nucleosides was similarly altered in the liver from the two PD mouse models. However, long-chain fatty acids, phosphatidylcholine and other related lipid metabolites were only altered in hepatocytes from G2019S-LRRK2 mice. In summary, these results reveal specific differences, mainly in lipid metabolism, between idiopathic and genetic PD models in peripheral tissues and open up new possibilities to better understand the etiology of this neurological disorder.This research was supported by “Instituto de Salud Carlos III”, “Fondo de Investigaciones Sanitarias” (PI15/0034), “CIBERNED-ISCIII” (CB06/05/0041 and 2015/03), and partially supported by “European Regional Development Fund (ERDF)” from the European Union. J.M.B.-S.P. is funded by “Ramon y Cajal Program” (RYC-2018-025099-I) and supported by Spain’s Ministerio de Ciencia e Innovación (PID2019-108827RA-I00). Y.C.N. and L.M.G. are funded by Community of Madrid (CT5/21/PEJ-2020-TL/BMD-17685 and CT36/22-41-UCM-INV respectively). S.M.S.Y.-D. was supported by CIBERNED-ISCIII. P.M.-C. is funded by the MINECO Spanish Ministry (FPI grant, PRE2020-092668). M.N.-S. was funded by “Ramon y Cajal Program” (RYC-2016-20883). E.U.-C. and S.C.-C. were supported by an FPU predoctoral fellowship (FPU16/00684) and FPU19/04435), respectively, from “Ministerio de Educación, Cultura y Deporte”. M.P-B was funded by a University of Extremadura fellowship. E.A-C was supported by a Grant (IB18048) from Junta de Extremadura, Spain. J.M.F. received research support from the “Instituto de Salud Carlos III”; “Fondo de Investigaciones Sanitarias” (PI15/0034) and CIBERNED-ISCIII (CB06/05/0041 and 2015/03). A.P.-C. was supported by MINECO (SAF2014-52940-R and SAF2017-85199-P). J.P.-T. received funding from CIBERNED-ISCIII (CB06/05/1123 and 2015/03). G.K. is supported by the Ligue contre le Cancer (équipe labellisée); Agence National de la Recherche (ANR)—Projets blancs; ANR under the frame of E-Rare-2, the ERANet for Research on Rare Diseases; AMMICa US/CNRS UMS3655; Association pour la recherche sur le cancer (ARC); Association “Le Cancer du Sein, Parlons-en!”; Cancéropôle Ile de-France; Chancelerie des universités de Paris (Legs Poix), Fondation pour la Recherche Médicale (FRM); a donation by Elior; European Research Area Network on Cardiovascular Diseases (ERA-CVD, MINOTAUR); Gustave Roussy Odyssea, the European Union Horizon 2020 Project Oncobiome; Fondation Carrefour; High-end Foreign Expert Program in China (GDW20171100085), Institut National du Cancer (INCa); Inserm (HTE); Institut Universitaire de France; LeDucq Foundation; the LabEx Immuno-Oncology (ANR-18-IDEX-0001); the RHU Torino Lumière; the Seerave Foundation; the SIRIC Stratified Oncology Cell DNA Repair and Tumor Immune Elimination (SOCRATE); and the SIRIC Cancer Research and Personalized Medicine (CARPEM).Peer reviewe

Marine viruses: Pieces of life essential for the functioning of the planet

Els virus marins s&oacute;n les entitats biol&ograve;giques m&eacute;s abundants que hi ha al mar. En un mil&middot;lilitre (ml) en trobem deu milions i en tot l&rsquo;oce&agrave; 1030. Infecten a tots els &eacute;ssers vius des de balenes fins a procariotes (bacteris i arqueus). Sent aquests darrers molt abundants (un mili&oacute; per ml), s&oacute;n els seus hostes preferits. Per tant, la major proporci&oacute; de virus que hi ha al mar s&oacute;n bacteri&ograve;fags (del grec, &lsquo;menjadors de bacteris&rsquo;) de doble cadena de DNA encara que tamb&eacute; se&rsquo;n troben d&rsquo;RNA. Tenen un paper cabdal a les xarxes tr&ograve;fiques microbianes. Quan lisen els seus hostes (per exemple, bacteris i fitopl&agrave;ncton), el contingut cel&middot;lular ric en mat&egrave;ria org&agrave;nica dissolta passa a la columna d&rsquo;aigua. Part d&rsquo;aquesta mat&egrave;ria org&agrave;nica pot ser aprofitada pels bacteris per cr&eacute;ixer i remineralitzada a nutrients inorg&agrave;nics (N, P, S), que podran ser utilitzats pel fitopl&agrave;ncton. Per tant, els virus desenvolupen un paper important en el control de l&rsquo;abund&agrave;ncia i diversitat de les comunitats microbianes i en els cicles biogeoqu&iacute;mics a l&rsquo;oce&agrave;. Per&ograve; no tots els virus s&oacute;n l&iacute;tics; n&rsquo;hi ha que s&rsquo;integren en el genoma de l&rsquo;hoste i esdevenen pr&ograve;fags. El pr&ograve;fag passa a ser un virus temperat i la c&egrave;l&middot;lula portadora &eacute;s el lisogen i pot transmetre&rsquo;l a moltes generacions (cicle lisog&egrave;nic), ja que la constituci&oacute; gen&egrave;tica del bacteri canvia degut als nous gens que aporta el virus. A conseq&uuml;&egrave;ncia de canvis ambientals i altres factors, el cicle lisog&egrave;nic pot revertir al cicle l&iacute;tic, i llen&ccedil;ar la nova prog&egrave;nie v&iacute;rica fora amb el contingut cel&middot;lular de l&rsquo;hoste. Els diferents tipus de cicle d&rsquo;infecci&oacute; (l&iacute;tic i lisog&egrave;nic) fan que els virus marins siguin el reservori m&eacute;s gran de diversitat gen&egrave;tica, ja que transfereixen gens dels hostes infectats a d&rsquo;altres hostes. Finalment, els virus tamb&eacute; tenen un paper important en la regulaci&oacute; del clima, ja que contribueixen a la producci&oacute; de nuclis de condensaci&oacute; que s&oacute;n la llavor per a la formaci&oacute; de n&uacute;vols, els quals es consideren elements que intervenen en el refredament del planeta.Paraules clau: virus, microorganismes, lisi, lisog&egrave;nia, nuclis de condensaci&oacute;.Marine viruses are the most abundant biological entities in the sea. We find 10 million in 1 ml and 1030 in the entire ocean. They infect all living beings, from whales to prokaryotes (bacteria and archaea). Since prokaryotes are very abundant (1 million per ml), they are the viruses&rsquo; favourite hosts. The largest proportion of viruses in the sea are double-stranded DNA bacteriophages, although RNA viruses are also found. In marine systems, viruses play a key role in the food web. When they lyse their hosts, they cause the cellular content rich in dissolved organic matter and recycled inorganic nutrients to enter the water column, where it is used by other bacteria and/or by photosynthetic microorganisms for their growth. Consequently, viruses control the abundance and diversity of the microbial communities and play a key role in the biogeochemical cycles in the ocean. But not all viruses are lytic: some integrate themselves into their host&rsquo;s genome and become prophages or temperate viruses. The carrier cell of the prophage or temperate virus is a lysogen and the prophage can be transmitted to further generations, causing changes in its genome. Environmental changes or cellular stress could revert the lysogenic cycle to the lytic cycle, releasing new viral progeny with the cellular content of the host. The different types of infection (lytic and lysogenic) make marine viruses the largest reservoir of genetic diversity, either stealing genes and/or transferring them to their hosts. Lastly, viruses also could play an important role in the regulation of the climate, contributing to the production of condensation nuclei that act as seeds for the formation of clouds, considered cooling elements of our planet.Keywords: viruses, microorganisms, lysis, lysogeny, condensation nuclei

Volatile Organic Compounds Released by <i>Oxyrrhis marina</i> Grazing on <i>Isochrysis galbana</i>

A range of volatile organic compounds (VOCs) have been found to be released during zooplankton grazing on microalgae cultivated for commercial purposes. However, production of grazing-derived VOCs from environmentally relevant species and their potential contribution to oceanic emissions to the atmosphere remains largely unexplored. Here, we aimed to qualitatively explore the suite of VOCs produced due to grazing using laboratory cultures of the marine microalga Isochrysis galbana and the herbivorous heterotrophic dinoflagellate Oxyrrhis marina with and without antibiotic treatment. The VOCs were measured using a Vocus proton-transfer-reaction time-of-flight mass spectrometer, coupled to a segmented flow coil equilibrator. We found alternative increases of dimethyl sulfide by up to 0.2 nmol dm−3 and methanethiol by up to 10 pmol dm−3 depending on the presence or absence of bacteria regulated by antibiotic treatment. Additionally, toluene and xylene increased by about 30 pmol dm−3 and 10 pmol dm−3, respectively during grazing only, supporting a biological source for these compounds. Overall, our results highlight that VOCs beyond dimethyl sulfide are released due to grazing, and prompt further quantification of this source in budgets and process-based understanding of VOC cycling in the surface ocean

Do microbes contribute to the FDOM signature in the ocean?

XXXII Trobades Científiques de la Mediterrània, Planeta Oceà - Planet Ocean, celebradas del 5 al 7 de octubre de 2016 en Maó, Menorca.-- Homenatge als Drs. Marta Estrada, Jordi Font i Jordi Salat, pioners de l'oceanografia mediterrània moderna. A tribute to Drs. Marta Estrada, Jordi Font and Jordi Salat, pioneers of modern Mediterranean oceanography.-- 1 pageSamples from the MALASPINA circumnavigation expedition (2010‐2011) were collected to study the influence of microbial abundances in the distribution of the fluorescent dissolved organic matter (FDOM). The FDOM excitation‐emission matrix (EEM) data, obtained using a Fluoromax‐4 spectrofluorimeter, were examined with Parallel Factor Analysis (PARAFAC). The PARAFAC analysis identified four components, two of them associated with humic‐like substances (C1 and C2) and the other two with protein‐like compounds (C3 and C4). In the specific context of this study, we will only refer to the protein‐like components: C3 corresponds to classic peak‐T, which is related to the essential aminoacid tryptophan (excitation‐emission 290/340 nm); and C4, associated to classic peak‐B, is related to the non‐essential aminoacid tyrosine (excitation‐emission 270/310 nm). We study the relationships between these two FDOM compounds and viruses and bacteria abundances compiled in the Malaspina database which includes values from 5 different oceanic basins (North Atlantic, South Atlantic, Indian, North Pacific and South Pacific). Samples were collected from 0 m to 4000 m depth, distinguishing three different layers (epipelagic 0‐200 m, mesopelagic 200‐1000 m, and bathypelagic 1000‐4000 m). Our aim was to determine if the dynamics of these FDOM components followed the evolution of the bacteria and/or viruses abundances. To achieve this objective we applied residual analyses to exclude the variability due to physicochemical parameters (temperature and salinity). When the whole database was considered, these parameters accounted for a high percentage (~60%) of both virus and prokaryotic variability. The residual analyses shown, in general, that the C3 component was significantly correlated to virus abundance. In contrast, only a weak C3‐prokaryotic abundance relationship was found in the mesopelagic zone of the North Pacific basin. On the other hand, C4 shown, in general, no clear relationship neither with prokaryotes nor viruses. Finally, we will discuss these results in the context of the usage of FDOM components as tracers of abundances and interactions of marine microbesPeer Reviewe

Detection of Virophages signatures in single amplified genomes (SAGs) of marine Stramenopiles

Red Española de Bacteriófagos y Elementos Transductores (FAGOMA), 2ª reunión FAGOMA II - Reunión IV, 26-27 October 2017, Alcúdia, MallorcaThe developments of techniques that allow us to obtain single amplified genomes (SAGs) have revolutionized the study of microorganisms without the need of culturing them. Here, we show the results of a SAG study on two kinds of marine Stramenopiles: the Chrysophite sp. G1 and the Marine Stramenopile 3A (MAST-3A). Our aim was to unveil new viral signatures present in SAGs using the data obtained in the TaraOcean expedition. The results obtained show the occurrence of a complete Mavirus virophage inside the genome of Chrysophite G1, here called G1_Chryso_Virophage, and another complete virophage inside the genome of MAST3A, here called MAST3A_Virophage. The G1_Chryso_Virophage is 95.72% similar with the annotated Maverick-related virophage infecting Cafeteria roerbengensis, while MAST3A_Virophage presents a 94.8% of similarity (alignments performed with MAFFT). Therefore, we conclude that we unveil two different kinds of new virophages, from the same family but infecting different speciesPeer Reviewe

Assessing the viral content of uncultured picoeukaryotes in the global-ocean by single cell genomics

18 pages, 4 figures, 2 tables, supporting information https://doi.org/10.1111/mec.15210Viruses are the most abundant biological entities on Earth and have fundamental ecological roles in controlling microbial communities. Yet, although their diversity is being increasingly explored, little is known about the extent of viral interactions with their protist hosts as most studies are limited to a few cultivated species. Here, we exploit the potential of single‐cell genomics to unveil viral associations in 65 individual cells of 11 essentially uncultured stramenopiles lineages sampled during the Tara Oceans expedition. We identified viral signals in 57% of the cells, covering nearly every lineage and with narrow host specificity signal. Only seven out of the 64 detected viruses displayed homologies to known viral sequences. A search for our viral sequences in global ocean metagenomes showed that they were preferentially found at the DCM and within the 0.2–3 µm size fraction. Some of the viral signals were widely distributed, while others geographically constrained. Among the viral signals we detected an endogenous mavirus virophage potentially integrated within the nuclear genome of two distant uncultured stramenopiles. Virophages have been previously reported as a cell's defence mechanism against other viruses, and may therefore play an important ecological role in regulating protist populations. Our results point to single‐cell genomics as a powerful tool to investigate viral associations in uncultured protists, suggesting a wide distribution of these relationships, and providing new insights into the global viral diversityThis work was supported by the Spanish projects MEFISTO (CTM2013‐43767‐P, MINECO), ALLFLAGS (CTM2016‐75083‐R, MINECO) and INTERACTOMICS (CTM2015‐69936‐P, MINECO), and the EU project SINGEK (H2020‐MSCA‐ITN‐2015‐675752). Y.M.C. was supported by a FPI Spanish fellowship (BES‐2014‐067849). J.F.M. was beneficiary of a Marie Curie Fellowship (PIEF‐GA‐2012‐331190, EU). L.F.B. was beneficiary of a Marie Curie Fellowship (H2020‐MSCA‐ITN‐2015‐675752, EU). R.L. was supported by a Ramón y Cajal fellowship (RYC‐2013‐12554, MINECO, Spain). H.O. was supported by JSPS/KAKENHI (No. 18H02279), and Scientific Research on Innovative Areas from the Ministry of Education, Culture, Science, Sports and Technology (MEXT) of Japan (Nos. 16H06429, 16K21723, 16H06437). O.J. was supported by The French Government ‘Investissement d'Avenir’ programmes Oceanomics (ANR‐11‐BTBR‐0008) and FRANCE GENOMIQUE (ANR‐10‐INBS‐09). M.S. was supported by a Viera y Clavijo contract funded by the ACIISI and the ULPGCPeer Reviewe

Viral abundance and community structure among four contrasting areas in the Southern Ocean and their implication to marine aerosol formation

4th Interlab Meeting, 22-23 May 2017, Banyuls-sur-Mer, FranceMarine viruses, together with other planktonic microorganisms, play an important role on the marine ecosystem functioning, and their activity can contribute on the marine aerosol composition. During the interdisciplinary PEGASO expedition, we visit four contrasting areas of the Southern Ocean (Antarctic and sub-antarctic), with high (South Giorgia Island) to low degree (Orkney Islands) of microplanktonic biomass and activity and derived secondary compounds concentration. In this study we aimed to (I) describe different viral community abundance and structures (distribution and diversity) among four contrasted areas; (II) relate them with their main hosts (bacteria and phytoplankton) as well as with physicochemical variables and (III) uncover their relation with metabolic secondary compounds generated by marine microbiological activity, which in turn, can be related with the marine aerosol compositionPeer Reviewe