3.2 Molecular responses of A. erythraea and its gut
microbiota on a DA diet
To find the potential detoxification mechanisms associated with the DA
diet, a metatranscriptome analysis was conducted. We analyzed the
results of A. erythraea and gut microbiota separately. A total of
844 million raw reads were generated, resulting in 752 million clean
reads. Among these, the average proportion of sequences mapped toA. erythraea was 26.69%, the average proportion mapped to gut
microbiota was 8.62%, and the detailed proportions for each sample are
provided in Table S2.
A. erythraea fed with toxic and non-toxic diets exhibited
distinct gene expression profiles (Fig. S3A). Through KEGG enrichment
analysis, we found that pathways involved in ingestion, such as protein
digestion and absorption (map04974) and lysosome (map04142), were
significantly downregulated on the toxic diet (Table S3). This
finding is consistent with the observed reduction in
grazing by A. erythraea on the toxic diet (Fig. 2A).Additionally , we found that processes related to cell
death and cell proliferation were significantly upregulated on
the toxic diet (Table S3), which was further supported by
stronger TUNEL and EdU signals observed in the toxic diet (Fig.
S4). This suggests that A. erythraea may accelerate cell
proliferation to repair damaged cells and mitigate the adverse effects
of DA.
We then examined the gene expression profiles of gut bacteria. Similar
to copepods, the PCA plot revealed that the toxic and non-toxic diets
clustered into distinct groups (Fig. 3A), indicating the different
expression profiles between the two. Compared to the non-toxic group,A. erythraea exhibited 9,867 DEGs on the first day (7,329
upregulated and 2,538 downregulated) and 23,871 DEGs on the second day
(13,757 upregulated and 10,114 downregulated) (Fig. 3B). To
further investigate, we conducted KEGG enrichment analysis on these
DEGs to identify key pathways activated by DA diet. In this
context , metabolism is the primary process involved in microbial
detoxification and adaptation to toxicity. Consequently , we
concentrated on the metabolic pathways that were significantly enriched
(adjusted p -value < 0.05). Eight metabolic pathways
were significantly upregulated on the first day, and twelve on the
second day (Fig. 3C; Table S4).