GSE176268
Rare earth elements show antagonistic interactions as revealed by transcriptome profiling in Chlamydomonas reinhardtii.
Purpose; Here we compare the transcriptomic effects of three REEs; Ce, Tm and Y, and a mixture of all three on Chlamydomonas reinhardtii in order to determine the degree of overlap of their effects. Methods; Transcriptome profiling (RNA-Seq) analysis performed on Chlamydomonas reinhardtii (wild-type strain, CC-125 aka 137c, Chlamydomonas resource center) exposed for 2 h to one of three soluble REEs (Ce, Tm, Y) salts at 0.5 µM or to an equimolar ternary mixture of these REEs. Illumina HiSeq (v.4) was used for the paired-end sequencing (2 × 100 base pairs) of 25 samples (5 replicates for each treatment: Ce; Tm; Y; Mix; Controls). For each sample, ca. 55 million of reads with their sequences, identification and quality scores were stored in two FastQ files. Results; Known functions of the differentially expressed genes support effects of REEs on protein processing in the endoplasmic reticulum, phosphate transport and the homeostasis of Fe and Ca. The only stress response detected related to protein misfolding in the endoplasmic reticulum. When the REEs were applied as a mixture, antagonistic effects were overwhelmingly observed with transcriptomic results suggesting that the REEs were initially competing with each other for bio-uptake. Conclusions; Our study represents the first detailed analysis of REE transcriptomic effects in a green microalga that is ubiquitous to fresh waters. Results generated by RNA-seq technology suggest that the approach of government agencies to regulate the REEs using biological effects data from single metal exposures may be a largely conservative approach. Overall design: mRNA profiles of Chlamydomonas reinhardtii exposed for 2 h to one of three soluble REEs (Ce, Tm, Y) salts at 0.5 µM or to an equimolar ternary mixture of these REEs