Comparative in depth RNA sequencing of P. tricornutum’s morphotypes reveals specific features of the oval morphotype

Abstract

Phaeodactylum tricornutum is the most studied diatom encountered principally in coastal unstable environments. It has been hypothesized that the great adaptability of P. tricornutum is probably due to its pleomorphism. Indeed, P. tricornutum is an atypical diatom since it can display three morphotypes: fusiform, triradiate and oval. Currently, little information is available regarding the physiological significance of this morphogenesis. In this study, we adapted P. tricornutum Pt3 strain to obtain algal culture particularly enriched in one dominant morphotype: fusiform, triradiate or oval. These cultures were used to run high-throughput RNA-Sequencing. The whole mRNA transcriptome of each morphotype was determined. Pairwise comparisons highlighted biological processes and molecular functions which are up- and down-regulated. Finally, intersection analysis allowed us to identify the specific features from the oval morphotype which is of particular interest as it is often described to be more resistant to stresses. This study represent the first transcriptome wide characterization of the three morphotypes from P. tricornutum performed on cultures specifically enriched issued from the same Pt3 strain. This work represents an important step for the understanding of the morphogenesis in P. tricornutum and highlights the particular features of the oval morphotype.

Characterization of a GDP-Fucose Transporter and a Fucosyltransferase Involved in the Fucosylation of Glycoproteins in the Diatom Phaeodactylum tricornutum

“…These residues have been demonstrated by directed mutagenesis to be involved in the binding to the acceptor substrate. Based on RNA-seq data recently reported in Ovide et al (2018), mainly Phatr3_J46109 and Phatr3_J54599 are expressed in the three morphotypes of P. tricornutum (fusiform, triradiate, and oval morphotypes).…”

“…The P. tricornutum strain Pt1.8.6 (CCAP1055/1) was grown in reconstituted artificial seawater (AQUARIUM SYSTEMS Instant Ocean) enriched with Conway medium containing 80 mg.L −1 of sodium metasilicate (Na2SiO3), at 19 ± 1°C as described previously in Ovide et al, 2018. The culture were grown under a 16 h/8 h light/night cycle (280–350 μmol photons m −2 ⋅s −1 ) and agitation at 150 rpm.…”

“…High pressure freezing, freeze substitution and transmission electron microscopy of P. tricornutum expressing V5-tagged FuT54599 or GnT I were carried out as described in Ovide et al (2018). Immunocytochemistry of V5-tagged transferases was carried out using antibodies raised against the V5 epitope (mouse anti-V5 tag antibodies, Invitrogen, dilution 1/20) and second antibody (EM-goat anti mouse IgG + IgM 10 nm gold particles, BBI solution, dilution 1/20).…”

Collective sinking promotes selective cell pairing in planktonic pennate diatoms

“…We carried out a series of laboratory experiments in suspensions of the planktonic fusiform morphotype of P . tricornutum (57–59). The LISST-100× Small Volume Flow Through Chamber (Sequoia Scientific, Inc.) was precleaned and filled with the desired vol/vol concentration of cell culture in growth medium.…”

GPCR Genes as Activators of Surface Colonization Pathways in a Model Marine Diatom

“…Moreover, we show that the induced expression of GPCR1A is sufficient to shift morphotypes, pointing to this protein as a potential target protein of screening anti-biofouling compounds. A comparative RNA-seq study on Phaeodactylum morphotypes was recently reported on the strain Pt3 ( Ovide et al., 2018 ), in which the major morphotype is oval (60%–75%) under liquid culture conditions. This phenotypic ratio is uncommon and is different in other strains of P .…”