Transcriptomic hallmarks of in vitro TiO2 nanotubes toxicity in Chlamydomonas reinhardtii

Recently, more accessible transcriptomic approaches have provided a new and deeper understanding of envi- ronmental toxicity. The present study focuses on the transcriptomic profiles of green microalgae Chlamydomonas reinhardtii exposed to new industrially promising material, TiO2 nanotubes (NTs), as an example of a widely used one-dimensional nanomaterial. The first algal in vitro assay included 2.5 and 7.5 mg/L TiO2 NTs, resulting in a dose-dependent negative effect on biological endpoints. At a working concentration of 7.5 mg/L, RNA - sequencing showed a mainly negative effect on the cells. In summary, the results indicated metabolic disrup- tion, such as ATP loss, damage to mitochondria and chloroplasts, loss of solutes due to permeated membranes, and cell wall damage. Moreover, apoptosis-induced transcripts were detected. Interestingly, reactivation of transposons was observed. In signalling and transcription pathways, including chromatin remodelling and locking, the annotated genes were downregulated.

Automated summary

Recently, more accessible transcriptomic approaches have improved our understanding of environmental toxicity. This study focused on the transcriptomic profiles of green microalgae Chlamydomonas reinhardtii exposed to TiO2 nanotubes (NTs), a commonly used one-dimensional nanomaterial. The results showed that the NTs had a dose-dependent negative effect on the algae, causing metabolic disruption, damage to cellular structures, solute loss, and cell wall damage. Additionally, apoptosis-related transcripts and reactivation of transposons were observed, while genes involved in signaling and transcription pathways were downregulated.