Transcriptomes of Rotaria rotatoria under thermal stress

Global warming has raised concerns regarding the potential impact on
aquatic biosafety and health. To illuminate the adaptive mechanisms of
bdelloid rotifers in response to global warming, the ecological and
transcriptomic characteristics of two strains (HX and ZJ) of Rotaria
rotatoria were investigated at 25°C and 35°C. Our results showed an
obvious genetic divergence between the two geographic populations. Thermal
stress significantly reduced the average lifespan of R. rotatoria in both
strains, but increased the offspring production in the ZJ strain.
Furthermore, the expression levels of genes Hsp70 were significantly
upregulated in the HX strain, while GSTo1 and Cu/Zn‐SOD were on the
contrary. In the ZJ strain, the expression levels of genes Hsp70, CAT2,
and GSTo1 were upregulated under thermal stress. Conversely, a significant
decrease in the expression level of the Mn‐SOD gene was observed in the ZJ
strain under thermal stress. Transcriptomic profiling analysis revealed a
total of 105 and 5288 differentially expressed genes (DEGs) in the HX and
ZJ strains under thermal stress, respectively. The PCA results showed
clear differences in gene expression pattern between HX and ZJ strains
under thermal stress. Interestingly, compared to the HX strain, numerous
downregulated DEGs in the ZJ strain were enriched into pathways related to
metabolism under thermal stress, suggesting that rotifers from the ZJ
strain prioritize resource allocation to reproduction by suppressing
costly metabolic processes. This finding is consistent with the life table
results. This study provides new insights into the adaptive evolution of
aquatic animals in the context of global climate change.