Marine diatoms change their gene expression profile when exposed to microscale turbulence under nutrient replete conditions

Alberto Amato,Gianluca Dell’Aquila,Nicolas Maillet,Remo Sanges,Rossella Annunziata,Francesco Musacchia,Maurizio Ribera D’Alcalà,Maria I Ferrante,Daniele Iudicone,Ari Ugarte,Alessandra Carbone

doi:10.1038/s41598-017-03741-6

Abstract

Diatoms are a fundamental microalgal phylum that thrives in turbulent environments. Despite several experimental and numerical studies, if and how diatoms may profit from turbulence is still an open question. One of the leading arguments is that turbulence favours nutrient uptake. Morphological features, such as the absence of flagella, the presence of a rigid exoskeleton and the micrometre size would support the possible passive but beneficial role of turbulence on diatoms. We demonstrate that in fact diatoms actively respond to turbulence in non-limiting nutrient conditions. TURBOGEN, a prototypic instrument to generate natural levels of microscale turbulence, was used to expose diatoms to the mechanical stimulus. Differential expression analyses, coupled with microscopy inspections, enabled us to study the morphological and transcriptional response of Chaetoceros decipiens to turbulence. Our target species responds to turbulence by activating energy storage pathways like fatty acid biosynthesis and by modifying its cell chain spectrum. Two other ecologically important species were examined and the occurrence of a morphological response was confirmed. These results challenge the view of phytoplankton as unsophisticated passive organisms.

Highlights

To cite this version: Alberto Amato, Gianluca Dell’aquila, Francesco Musacchia, Rossella Annunziata, Ari Ugarte, et al
This is important for unicellular phytoplankton which are surrounded by a fluid boundary layer where molecular diffusion is the dominant process and only solute chemical gradients assure cell provisioning
Our results showed that C. decipiens responded both morphologically and at the gene expression level to the treatment

Summary

Introduction

To cite this version: Alberto Amato, Gianluca Dell’aquila, Francesco Musacchia, Rossella Annunziata, Ari Ugarte, et al. Fluid motion introduces kinetic energy in the system and turbulence is the way kinetic energy is transferred, through a dissipation cascade, over several eddy-like structures down to the smallest scale This scale, energy is dissipated to heat via the friction of viscosity and water motion cannot prevail over molecular diffusion but can control it by changing local gradients[2, 3]. Energy is dissipated to heat via the friction of viscosity and water motion cannot prevail over molecular diffusion but can control it by changing local gradients[2, 3] This is important for unicellular phytoplankton which are surrounded by a fluid boundary layer where molecular diffusion is the dominant process and only solute (nutrient) chemical gradients assure cell provisioning. Shear stress is what cells below Kolmogorov scale would perceive www.nature.com/scientificreports/

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