7ème - roscoff · 2018. 4. 25. · 7éme journée des jeunes chercheurs de la station biologique...

7ème

Journée des Jeunes

Chercheurs de la station

biologique de Roscoff

Posters

Résumés - Abstracts

7éme Journée des Jeunes Chercheurs de la Station Biologique de Roscoff – 3 décembre 2015 – Résumés Posters 2

Evolutionary history of PGM variants and the adaptive effect of QE

mutations on protein thermostability in the Pompeii worm

Alexis BIOY1, Jean MARY

1, Anne-Sophie LE PORT

1, Didier JOLLIVET

1

1The ABICE Team. UMR 7144 CNRS-UPMC, Station Biologique de Roscoff, Place Georges Teissier, 29680

Roscoff FRANCE

KEYWORDS: Phosphoglucomutase, Thermal variability, Balancing selection

The Pompeii worm occurs exclusively on hydrothermal-vent chimneys along the East Pacific Rise (EPR).

This environment is considered as one of the most extreme and variable in temperature. Previous works on the

Phosphoglucomutase revealed that diversifying selection acts on the frequencies of isoforms 78, 90 and 100

between thermal habitats at small spatial scales. Both protein stability and thermal optimum of enzyme activity

were clearly different between isoforms. Allozymes also displayed a clinal distribution from North to South with

an abrupt replacement of isoform 100 by isoform 78. In the present study, alleles encoding these isoforms were

completely sequenced from northern and southern individuals. The distribution of highly divergent alleles

without recombination on both sides if the EPR are likely the result of balancing selection combined with spatial

isolation. Only two non-synonymous mutations (EQ) located in the exon 3 explain the polymorphism of charge.

Directional mutagenesis allowed us to mutate allele 100 into the two other alleles and to overexpress them to

explore the additive effect of the mutations over the biochemical properties of the enzyme in the face of

temperature. Results are coherent with those obtained on native proteins and showed the direct effect of

mutations on the protein thermostability.


Past and contemporary introgression between two strongly differentiated

Ciona species as revealed by the analysis of a post-genomic SNP panels

Sarah BOUCHEMOUSSE1, Cathy HAAG-LIAUTARD

2,3, Nicolas BIERNE

2,3 & Frédérique VIARD

1

1Sorbonne Universités, UPMC Univ Paris 6, CNRS, UMR 7144, Equipe Div&Co, Stations Biologique

de Roscoff, Place Georges Teissier, 29680 Roscoff, France

2Université Montpellier 2, Station Méditerranéenne de l’Environnement Littoral, 2 rue des Chantiers,

34200 Sète, France

3CNRS-UM2-IRD, UMR 5554, Institut des Sciences de l’Evolution, Place Eugène Bataillon, 34095

Montpellier, France

KEYWORDS: Biological invasions, Tunicates, Hybridization, Species range, Population

genomics

One important outcome of biological introductions is to bring into contact species

that diverged in allopatry. For interfertile taxa, the evolutionary outcomes of such secondary

contacts may be diverse (e.g. adaptive introgression from or into the introduced species) but

are not yet well examined in the wild. In this context, the recent secondary contact between

the non-native species Ciona robusta and the native species C.intestinalis, in the English

Channel, provides an excellent case study to examine. By means of a population genomic

approach, using 310 SNPs developed from full transcriptomes, the genetic diversity at

population and species level was examined by studying 449 individuals sampled in 12 sites

from the English Channel, North Sea, NW Atlantic and SE Pacific where they are found

either alone or living in the same locality and habitat (syntopy). As expected from previous

analyses, C. robusta showed less heterozygosity than C. intestinalis, a pattern that may partly

be explained by its non-native status in most of the study localities. The results clearly

showed an almost complete absence of contemporary gene flow between the two species in

syntopic localities, with only one first generation hybrid and none other genotype compatible

with recent backcrosses. Interestingly, introgression was also observed in allopatric

populations of both species (i.e. where no contemporary hybridization can occur).

Furthermore, one allopatric population sampled in SE Pacific exhibited a much higher

introgression rate compared to all others C. robusta populations. Altogether, these results

indicate that the observed inter-specific gene flow is the outcome of historical introgression,

spread afterward at a worldwide scale. They also point out that efficient barriers are

preventing hybridization in the wild between the introduced and native species in the English

Channel, thus making adaptive introgression of the introduced species unlikely to favor the

sustainable establishment of the study species.


Marine cyanobacteria lipid metabolism and latitudinal temperature

gradient

Solène BRETON 1

1Station Biologique de Roscoff, France

KEYWORDS: Marine Synechococcus, Temperature, Lipid metabolism

Marine cyanobacteria are the smallest and most abundant photosynthetic organisms, ensuring almost

20% of the global oceanic primary production. Among this group, Synechococcus cells (Figure 1) show the

widest latitudinal distribution as they are detected from the equator to the polar

circles. This quasi ubiquity seems to be linked with the large genetic diversity of

these cyanobacteria. Indeed, it has been demonstrated that, during evolution,

marine Synechococcus have differentiated lineages physiologically adapted to

the different thermal niches of the latitudinal gradient of temperature

(thermotypes). However, the physiological mechanisms underlying this

thermoadaptation still remain unknown.

The biomembranes are well known for the high thermal sensitivity of

their lipid matrix, whose fluidity must be tightly regulated to ensure the correct

functioning of the system. Indeed, in these membranes are inserted many

proteins participating to crucial cellular metabolisms, such as photosynthesis.

For those phototrophic organisms, membrane regulation is essential, particularly

in different thermal environments. The capacities of marine Synechococcus to

regulate their membrane could be one of the keys for understanding their

differential thermoadaptation capacities.

Cyanobacterial membranes are composed of four dominant glycerolipids which include different fatty

acid chains. Until now, only very few data are available concerning the lipid membrane composition and the

regulation of membrane synthesis in marine Synechococcus. The aim of my PhD is to study the links between

marine Synechococcus thermophysiology and their thermal niche partitioning by exploring their membranar lipid

diversity, and the role of these compounds in the differential thermoacclimation capacities of the marine

Synechococcus thermotypes.

REFERENCES

Kana, T. M. and P. M. Glibert, 1987. "Effect of irradiances up to 2000 µ.Em- 2 s- 1 on marine Synechococcus WH7803 I.

Growth, pigmentation, and cell composition. DeepSea Res. 34 : 479-495

Figure 1 : Electron microscopy picture of a Synechococcus sp. WH7803 cell (Kana and Glibert

1987)


The protein kinase Haspin as new therapeutic target;

analysis of function, regulation and characterization of specific inhibitors.

Omid FEIZBAKHASH1, Jonathan ELIE

2, Xavier FANT

1, Blandine BARATTE

1, Nathalie DESBAN

1, Sylvain

ROUTIER2, Frédéric BURON

2, Pascal BONNET

2, Mohamed MEHIRI

3 and Sandrine RUCHAUD

1

1CNRS/UPMC, USR 3151,Station Biologique de Roscoff, Phosphorylation of Proteins and Human

Diseases

2ICOA,Université d’Orléans, Orléans

3I.C.N, CNRS UMR 7272, Université de Nice, Nice

KEYWORDS: Haspin, Protein Kinases, Mitosis, Cancer

Cancer is a current and important topic in the field of human health. New therapeutic targets for this

disease have emerged, such as protein kinases and notably those implicated in mitosis. Among them is the Ser /

Thr protein kinase Haspin, a chromosome-associated kinase essential for mitosis, where it is required for

chromosome alignment, centromeric cohesion and mitotic spindle integrity. Its particular role in mitosis and the

specific characteristics of this protein make it an interesting new therapeutic target against cancer.

This thesis project is divided in two parts. In to the first part I will study the biological functions and

the mechanisms of regulation of Haspin activity using RNAi/complement- ation, chemical genetics, and high-

resolution microscopy methodologies. In the second part, collaborations with KISSf (Kinase Inhibitory

Specialized Screening facility-USR 3151) and different chemists will allow us to identify and characterize new

Haspin’s inhibitory molecules,especially of marine origin by enzymatic and/or phenotypic screening These

molecules will in turn help us to better decipher Haspin’s molecular mode of action and functions of which little

is known.

Together, this research will help us understand the kinase functions and allow us to find inhibitory

molecules specific of Haspin, which may be used as anticancer therapeutics.


Unexpected relative stability of sublittoral macrobenthos in response to

climate change in a biogeographical transition zone

François GAUDIN 1,2

, Nicolas DESROY 2,

NADIA AMÉZIANE

3, CAROLINE BROUDIN

4, ANTOINE CARLIER

5,

STANISLAS DUBOIS5, JEROME FOURNIER

6, AURELIE FOVEAU

2, FRANCK GENTIL

1, JACQUES GRALL

7,

CELINE HOUBIN4, LISE LATRY

8, PATRICK LE MAO

2, ERIC THIÉBAUT

1

1 Sorbonne Universités, UPMC Univ Paris 6, CNRS, Station Biologique de Roscoff, UMR 7144 Adaptation et

Diversité en Milieu Marin, Place Georges Teissier, CS 90074, 29688 Roscoff cedex, France 2 IFREMER, Laboratoire Environnement & Ressources Bretagne Nord, CRESCO, 38 Rue du Port

Blanc, BP 70134, 35801 Dinard cedex,France

3 Sorbonne Universités, Muséum National d’Histoire Naturelle, UMR 7208-MNHN-CNRS-ParisVI-

IRD, Station Marine de Concarneau, BP225, 29182 Concarneau Cedex, France

4 Sorbonne Universités, UPMC Univ Paris 6, CNRS, Station Biologique de Roscoff, FR2424, Place

Georges Teissier, CS 90074, 29688 Roscoff cedex, France

5 IFREMER, DYNECO Ecologie Benthique, ZI de la Pointe du Diable, CS10070, 29280 Plouzané,

France

6 CNRS, UMR 7208 BOREA, 61 rue Buffon, CP 53, 75231 Paris cedex 05, France

7 UMS 3113, Observatoire des Sciences de l’Univers, IUEM, Place Nicolas Copernic, 29280

Plouzané, France

8 Station Marine de Dinard, USM 404, Muséum National d'Histoire Naturelle, 38 Rue du Port Blanc,

35800 Dinard, France

KEYWORDS: CLIMATE CHANGE, MACROFAUNA, ENGLISH CHANNEL

In the North-East Atlantic, the English Channel constitutes a biogeographical transition zone between

the cold-temperate Boreal province in the North and the warm-temperate Lusitanian province in the South.

Historical works have shown that the distribution of macrobenthic invertebrates in the Channel was influenced

by thermal gradients from West to East so that many species were here in their southern or northern range limits.

In parallel, long-term environmental monitoring highlighted an increase in the sea temperature during the last 30

years and a thermal regime shift in the North-West Europe since the 1980’s. Accordingly, major changes on the

distribution of subtidal macrobenthic fauna are expected as documented for fish, plankton and intertidal

organisms. Our results based on a comparison of data collected for molluscs, echinoderms and decapods during a

cool period in the 1970’s and the present (2012-2014) at 445 and 254 stations distributed along three transects

from the Iroise Sea to the central Channel did not confirm this expectation. On the contrary, they suggest only

few distribution shifts, not clearly associated to warming but a decrease in the occurrence for most species.

These results will be discussed in the light of spatial heterogeneity in climate change and fishing pressure.


The influence of bacteria on the adaptation to changing salinities in

Ectocarpus subulatus: a systems biology approach

Hetty KLEINJAN1,2

, Simon M. DITTAMI1,2

, Catherine BOYEN1,2

1 Sorbonne Universités, UPMC Univ. Paris 06, UMR 8227, Integrative Biology of Marine Models, Station

Biologique de Roscoff, Roscoff, France 2 CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France

KEYWORDS: ALGAL-BACTERIAL INTERACTIONS, HOLOBIONT, METABOLIC NETWORKS

Algae live in close association with microbes, e.g. symbiotic bacteria, and their interactions are

important determinants for algal performance and physiology. Despite these clear observations, the

role of algal-bacterial interactions in adaptation and acclimation processes often goes unnoticed. Here,

we study the fresh water strain (FWS) of Ectocarpus subulatus, a small brown filamentous algae. This

strain has shown to tolerate a broad range of salinities compared to other algae within the

Ectocarpales. (Dittami et al. 2012). The FWS is therefore an interesting model to study acclimation

processes, such as acclimation to changing salinities. Interestingly, axenic cultures of FWS do no

longer thrive in low salinity media, while inoculation with xenic media restores fresh water tolerance

(Dittami et al. 2015). These result show the importance of algal-bacterial interactions in the

acclimation of FWS to low salinity. Additionally, it stresses the importance to study the algal-bacterial

microecosystem as one entity, the so-called holobiont (Bordenstein and Theis 2015; Egan et al. 2013)

REFERENCES

Bordenstein, Seth R, and Kevin R Theis. 2015. “Host Biology in Light of the Microbiome: Ten Principles of Holobionts and Hologenomes.”

PLoS Biol 13 (8). Public Library of Science

Dittami Simon M, Duboscq-Bidot L, Perennou M, Gobet A, Corre E, Boyen C, et al. 2015. “Host-Microbe Interactions as a Driver of

Acclimation to Salinity Gradients in Brown Algal Cultures.” ISME J. in press.

Dittami, Simon M., Antoine Gravot, Sophie Goulitquer, Sylvie Rousvoal, Akira F. Peters, Alain Bouchereau, Catherine Boyen, and Thierry Tonon. 2012. “Towards Deciphering Dynamic Changes and Evolutionary Mechanisms Involved in the Adaptation to Low Salinities

in Ectocarpus (brown Algae).” Plant Journal 71 (3): 366–77.

Egan, Suhelen, Tilmann Harder, Catherine Burke, Peter Steinberg, Staffan Kjelleberg, and Torsten Thomas. 2013. “The Seaweed Holobiont:

Understanding Seaweed–bacteria Interactions.” FEMS Microbiology Reviews 37 (3): 462–76.


Seeking for new enzymes active on algal polysaccharides

Maria MATARD1,2

1UPMC, France

2Amadéite SAS - Olmix group, France

KEYWORDS: Enzymes, Algal cell-wall, Polysaccharides

What a wonderful world it would be if we could replace plastic from petrochemical industries by new

biopolymers from renewable sources, if we could bread our productive livestock without any antibiotics or find

new medicines against dreadful diseases… And if the solutions were under the sea? The sea gave birth to the life

and among the first eukaryotic organisms that appeared around 1.5 billion years ago were algae1. They evolved

and gave birth to terrestrial plants about 700 million years ago2. Today, more than 50% of our pharmaceutical

products are derived from natural origine3 but very few from the sea, and even less from seaweeds. One reason

explaining why algae have been underexploited so far, is the lack of means to deal with their complex cell-well.

But natural tools have been developed by the bacteria living on macroalgae. Indeed they produce a high diversity

of enzymes allowing them to degrade the complex polysaccharidic lattice of algal cell-wall4,5

. One of the aims of

my thesis is to discover new enzymes in the genome of marine bacteria and to characterize their activity. This

will allow, in the near future, to develop tools for valorization of the “blue-gold” trapped into algae.


“Genetic and cellular characterization of gamete parthenogenesis in brown

alga Ectocarpus”

Laure Mignerot1

Supervisors: Susana Coelho1, Mark Cock

1

1UMR 8227 CNRS-UPMC, Integrative Biology of Marine Models Laboratory, Algal Genetics Group,

Station Biologique, Place Georges Tessier, 29680 ROSCOFF, France

KEYWORDS: Asexual reproduction, Brown Algae, Sex locus

In the last decades, Ectocarpus, a small alga from the Stramenopile’s group, has been used as a model

for brown algae. Current research projects in the Algal Genetics Group are aimed at understanding the

reproductive biology of this filamentous alga, its life cycle and how developmental processes work. The life

cycle of Ectocarpus can be sexual or asexual, via parthenogenesis. Parthenogenesis occurs when a gamete

develops into a new individual without fusion with a gamete from the opposite sex. It is a process that is very

rare in mammals and that can be found in numerous plants and some insects. Parthenogenesis has been analyzed

in a population of Ectocarpus siliculosus from Naples, where usually only female gametes can make the

parthenogenesis. This results lead us to believe that there could be a genetic link between parthenogenesis and

the sex locus.

My PhD project is to investigate the genetic and cellular basis of gamete parthenogenesis in Ectocarpus

using approaches to fine map the parthenogenesis locus, and to investigate the function and the phenotypic effect

of this locus in gametes.


Flexibility of the symbiosis between Bathymodiolus (Bivalvia :

Mytilidae) and chemosynthetic bacteria

Piquet B.

1,2,3,4, Quiles A.

3,4, Andersen A.C.

1,2 and Duperron S.

3,5

1Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 6, UMR 7144, Équipe

Adaptation et Biologie des Invertébrés en Conditions Extrêmes, Station Biologique, F-29680 Roscoff, France. 2 CNRS, UMR 7144: Adaptation et Diversité en Milieu Marin, Station Biologique, F-29680 Roscoff,

France 3 Sorbonne Universités, Université Pierre et Marie Curie, Université Paris 6, Institut Universitaire de

France, UMR 7208, Equipe Adaptation aux Milieux Extrêmes, Quai Saint-Bernard, Bat. A, 75005 Paris, France 4 CNRS, UMR 7208 Biologie des Organismes et Ecosystèmes Aquatiques, Paris, France

5 Institut Universitaire de France, Paris, France

Lors de ma thèse, je vais étudier des Bathymodioles (Bivalvia : Mytilidae) qui abritent dans

leurs branchies des bactéries chimiotrophes. Cette symbiose permet aux moules de coloniser des

milieux contraignant comme les sources hydrothermales et les suintements froids. En utilisant le

méthane et/ou le sulfure comme source d’énergie, les symbiontes synthétisent des glucides qui sont la

principale source d’alimentation de leurs hôtes. Cette symbiose étant flexible, mon but sera d’éclairer

les mécanismes qui la régulent. Comment l’hôte régule-t-il la quantité de bactéries présentent dans ses

branchies (Apoptose, endo-exocytose, digestion des bactéries,…) ? Et les bactéries sont-elles capables

d’échapper à leur hôte ? Pour répondre à ces questions différentes méthodes vont être utilisées en

histologie (Immunohistologie, microscopie à transmission, FISH, TUNEL, BrdU,…) mais aussi des

approches en transcriptomiques seront effectuées sur les individus montrant les réponses les plus

marquées. Cette thèse se déroulera entre deux équipes : l’équipe ABICE de l’UMR 7144 à la Station

Biologique de Roscoff et l’équipe AMEX de l’UMR BOREA au Campus de Jussieu UPMC.

During my PhD, I’ll study Bathymodioline mussels (Bivalvia: Mytilidae), which house

chemotrophic bacteria in their gills. This symbiosis allows mussels to colonize restrictive environment

like hydrothermal vents and cold seeps. By using methane and/or sulphur as a source of energy,

symbionts synthesize glucide, which are the major main food source for their host. This symbioses

being flexible, my objective will be to understand on mechanisms that control symbiosis. How host

controls the bacteria quantity present in its gills? (Apoptosis, endo-exocytosis, digestion of

bacteria…)? And does bacteria be able to escape from their host? To find an answer, different

techniques will be used in histology (Immunohistology, transmission electron microscopy, FISH,

TUNEL, BrdU…) but also others approaches in transcriptomic will be performed on subject showing

the most marked responses. This PhD will take place between two teams: Team ABICE from UMR

7144 at the Station Biologique de Roscoff and team AMEX from UMR BOREA at the Campus de

Jussieu UPMC.


Morpho-functional exploration of protists in symbiosis with cyanobacteria

Thibaut Pollina1, Sebastien Colin, Sarah Romac, Colomban de Vargas

1Station Biologique de Roscoff

KEYWORDS: Symbiosis, Plankton, Protists, Single-cell, Cyanobacteria, Phycoerythrin

The analysis of plastidial 16S rRNA barcodes revealed specific cyanobacterial diversity in high size

fractions (20-180µm and 180-2000µm) of Tara Oceans oligotrophic stations. Their presence suggests

associations with large organisms. Additionally using confocal microscopy we described the structural

organization of several known and novel consortia involving cyanobacteria. Further investigations of such

interactions (mutualism, predation, aggregation) requests to crosslinked genetic and morphological worlds. We

then setup on purpose a morpho-genetic technical approach to image and isolate these consortia. The

phycoerythrin, which is a pigment that is found in most of cyanobacteria and which forms an effective

fluorescent label, was used to detect them. Using a microscope equipped with a micro-manipulator, we were able

to image and pick up single eukaryotic cells displaying association with cyanobacteria. We sorted more than 150

of them, present in the micro-plankton (20-180 µm size fraction) of various oligotrophic water masses. 18S and

16S rDNA barcodes were sequenced from these holobionts in order to identify the partners of each consortiums.

Thanks to the global dataset of Tara Oceans, we will quantify the prevalence of these associations and analyse

correlation with biological and environmental parameters.


Tip-growth in the brown alga Ectocarpus sp.: identification of the

cellular and molecular processes affected in the mutants ecballium and

étoile

Hervé RABILLE1, Bénédicte CHARRIER

1

1 CNRS, Université Pierre et Marie Curie Paris-06, Morphogenesis of MacroAlgae Team

KEYWORDS:

Tip-growth is a common cellular process found in several lineages of multicellular eukaryotes,

including metazoan, land plants, eumycetes, oomycetes and the various clades of algae. It ensures a rapid

colonization of the environment and an efficient invasion of stiff medium, by an extremely polarised cellular

growth generating a narrow tubular shape. Whereas in land plants and fungi, importance of the cell wall, of the

cytoskeleton and of the turgor pressure have been demonstrated (Guerriero et al., 2014), and mechanistic models

have been proposed using some of these cellular actors, only drug treatments and microscopic study could

establish the probable importance of the cytoskeleton in tip-growth in brown algae (Katsaros et al., 2006).

Moreover, their particular evolutionary history and environment and their morphological diversity, brown algae

are a particularly interesting groups to study the process of tip-growth. The thesis project aims to acquire

cytological, biophysical and molecular data on the growing apical cell of Ectocarpus, a filamentous model

brown alga, in order to propose a mechanistic model of tip-growth in brown algae. Two mutants, called étoile

(Le Bail et al., 2011) and ecballium, that are affected in tip-growth, will be characterised in parallel with the WT

(Ec32 strain). While étoile is characterised by production of spherical apical cells and subsequent arrest of apical

growth, ecballium displays an abnormal propensity to apex bursting. The three main cellular parameter (cell

wall, turgor pressure, cytoskeleton…) and the transcriptomic profile of the apical cells will be characterised

using a panel of technic developed for the Ectocarpus model. Growth dynamic will be recorded by time-laps

microscopy. Structure and physical properties of the cell wall will be characterised using Atomic Force and

Transmission Electronic Microscopy, and cell dilation / retraction under osmotic shocks. Variation in cell wall

properties will eventually be connected to particular polysaccharides or protein composition using monoclonal

antibodies (collab. Cécile Hervé, UMR 8227; Torode et al., 2015) or specific enzymatic treatment. Turgor

pressure will be measured in apical cells using limit plasmolysis technic. Organisation and function of the

cytoskeleton will be addressed using fluorescence immunolocalisation and drugs treatments. Transcriptomic

profile of the apical cell will be obtained by Laser Capture Microdissection and subsequent RNA-sequencing.

Whereas ETOILE gene has already been identified, and code for a Rho-GTPase-Activating-Protein, the mutated

gene in ecballium will be identified using a combination of genetic mapping and shore-map sequencing

(according to the method described in Billoub et al., 2015). All these data will allow us to propose a conceptual

model of tip-growth in brown algae, integrating both physical, cellular and molecular actor, and to compare it to

those known for land plants and fungi, perhaps reveaing specificity and originality of the fundamental

development process in brown algae.


Mosaic hybridization and genetic structure in two species of the

Jaera albifrons complex

Ambre RIBARDIERE 1

1University Pierre and Marie Curie, Station Biologique de Roscoff, France

Diversity of green micro-algae in marine waters (poster)

Margot TRAGIN 1, Adriana LOPES

1, Daniel VAULOT

1

1Sorbonne Universités, UPMC (PARIS-06), CNRS, UMR 7144, Station Biologique de Roscoff, Plage

G.Tessier, 29680 Roscoff, France

KEYWORDS: Chlorophyta, Diversity, Distribution, Marine systems, Databases

In contrast to freshwaters, green algae have been relatively little studied in marine waters. Two major

lineages are represented in the ocean, core Chlorophyta and prasinophytes. Prasinophytes are a complex

assemblage of classes, clades and individual branches in need of urgent taxonomic revisions. The recent

development of high throughput sequencing technology (HTS) is providing very large metabarcoding datasets to

explore the diversity and distribution of protist groups in the ocean, in particular using specific regions of the

18S rRNA gene. The first step to analyze these data sets is to establish a database containing reference

sequences with validated taxonomic annotations. For this purpose, we retrieved from the Protist Ribosomal

Reference database (PR²), 18S rRNA Chlorophyta sequences from culture and natural samples. We verified the

taxonomic affiliation of each sequence, filtered out chimeras, added metadata available from GenBank and built

a new 18S reference database. This database allowed us to map the distribution of the different Chlorophyta

groups in marine waters from existing sequences.

7ème - roscoff · 2018. 4. 25. · 7éme journée des jeunes chercheurs de la station biologique...

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