Rapid transcriptomic and physiological changes in the freshwater pennate diatomMayamaea pseudoterrestrisin response to copper exposure

Abstract

Diatoms function as major primary producers, accumulating large amounts of biomass in most aquatic environments. Given their rapid responses to changes in environmental conditions, diatoms are used for the biological monitoring of water quality and for performing ecotoxicological tests in aquatic ecosystems. However, the molecular basis for their toxicity to chemical compounds remains largely unknown. Here, we sequenced the genome of a freshwater diatom, Mayamaea pseudoterrestris NIES-4280, which has been proposed as an alternative strain of Navicula pelliculosa UTEX 664 for performing the Organisation for Economic Co-operation and Development ecotoxicological test. This study shows that M. pseudoterrestris has a small genome and carries the lowest number of genes among freshwater diatoms. The gene content of M. pseudoterrestris is similar to that of the model marine diatom, Phaeodactylum tricornutum. Genes related to cell motility, polysaccharide metabolism, oxidative stress alleviation, intracellular calcium signaling, and reactive compound detoxification showed rapid changes in their expression patterns in response to copper exposure. Active gliding motility was observed in response to copper addition, and copper exposure decreased intracellular calcium concentration. These findings enhance our understanding of the environmental adaptation of diatoms, and elucidate the molecular basis of toxicity of chemical compounds in algae.

Local adaptation of a marine diatom is governed by genome-wide changes in diverse metabolic processes

“…Most strikingly, these F ST outliers are enriched for signal transduction, cell communication, response to external stimuli, and defense response. This includes various protein kinases: (i) calcium/calmodulin-dependent protein kinases which are differentially expressed in S. marinoi in response to hyposalinity (11) and which might play a role in osmotic sensing in diatoms (54), (ii) serine/threonine protein kinases, including mTOR , which have been involved in stress responses and resting cell formation in diatoms (55, 56), (iii) cGMP-dependent protein kinases, which play a role in the salt stress response of plants (57), and are differentially expressed in diatoms in response to copper exposure and deficiency (58), (iv) histidine kinases, which are involved in signal transduction across the cell membrane, nutrient sensing, light perception, and oxidative and osmotic stress response in plants, fungi, and algae (59), and lastly, (v) cAMP-dependent protein kinases which rely on the ancient signaling molecule cAMP that serves as a stress indicator across the tree of life (60). Several of the histidine kinases were also GEA-outliers.…”

Channels of Evolution: Unveiling Evolutionary Patterns in Diatom Ca2+ Signalling

“…Further species must therefore be examined in order to assess whether these trends reflect species-specific variability or represent broader trends between centric and pennate lineages. The number of available diatom genomes has recently increased significantly [25][26][27][28][29][30][31][32][33][34]. Our aim was to examine the diversity of Ca 2+ channel types across a wider variety of diatom species to determine broad trends in their composition in comparison with other photosynthetic stramenopiles.…”