An integrated transcriptome-microbiome host relationship associated with paraben toxicity in the brackish water flea Diaphanosoma celebensis.

Parabens, a group of alkyl esters of p-hydroxybenzoic acid, have been found in aquatic systems in particular, leading to concerns about their potential impact on ecosystems. This study investigated the effects of three commonly used parabens, methylparaben (MeP), ethylparaben (EtP), and propylparaben (PrP), on the brackish water flea Diaphanosoma celebensis. The results showed that PrP had the most adverse impact on survival rates, followed by EtP and MeP, while MeP and EtP induced significant adverse effects on reproductive performance. A transcriptome analysis revealed significant differential gene expression patterns in response to paraben exposure, with MeP associated with the most significant effects. MeP and EtP exposure produced greater disruption in the microbiota of D. celebensis than did PrP compared with control groups, and we identified eight key microbiota, including Ruegeria and Roseovarius. Correlation analysis between transcriptome and microbiome data revealed key interactions between specific microbiota and host gene expression. Certain microbial taxa were associated with specific genes (e.g. cuticle related genes) and toxicological pathways, shedding light on the complex molecular response and in vivo toxicity effects of parabens. These findings contribute to a deeper understanding of the molecular mechanisms underlying paraben toxicity and highlight the importance of considering the ecological impact of chemical contaminants in aquatic ecosystems.

Comparative Microbiome Analysis of Artemia spp. and Potential Role of Microbiota in Cyst Hatching.

Brine shrimp (Artemia spp.) is a significant factor in determining aquaculture production. Since the microbiota of Artemia can colonize the gut in larvae, various microorganisms transmitted from Artemia can affect host larval health. Although the microbiota composition of Artemia would be essential in determining aquaculture productivity, our understanding on microbiome of Artemia is still insufficient. Through our study, we identified the species of Artemia cysts supplied by three different manufacturers (P1, P2, and P3) with investigation of size and hatching efficiency. The species of Artemia from P1 was identified as A. tibetiana, and P2 and P3 was A. franciscana. A. tibetiana hatched from the P1 cysts had the largest body size with the lowest hatching rate. Furthermore, we conducted a comprehensive analysis of the microbiome present in the rearing water and the nauplius whole body from each product. We observed specific microbiota compositions, both beneficial and harmful, depending on the product types and the sample types. Additionally, we found that the microbiota composition in the rearing water was associated with the manufacturing environment, while the compositions in the nauplius whole body were species-specific. Notably, we discovered that an extract containing microbiota from the nauplius sample of P3 increased the hatching rate of A. tibetiana, indicating a positive role in Artemia culture. These findings demonstrate that the microbial communities present in Artemia vary according to the product and/or species, underscoring their significance in aquaculture production.

Transcriptional and toxic responses to saxitoxin exposure in the marine copepod Tigriopus japonicus.

Saxitoxin (STX) is a highly toxic marine neurotoxin produced by phytoplankton and a growing threat to ecosystems worldwide due to the spread of toxic algae. Although STX is an established sodium channel blocker, the overall profile of transcriptional levels in STX-exposed organisms has yet to be described. Here, we describe a toxicity assay and transcriptome analysis of the copepod Tigriopus japonicus exposed to STX. The half-maximal lethal concentration of STX was 12.35 µM, and a rapid mortality slope was evident at concentrations between 12 and 13 µM. STX induced changes in swimming behavior among the copepods after 10 min of exposure. In transcriptome analysis, gene ontology revealed that the genes involved in nervous system and gene expression were highly enriched. In addition, the congenital neurological disorder and nuclear factor erythroid 2-related factor 2-mediated oxidative stress pathways were identified to be the most significant in network analysis and toxicity pathway analysis, respectively. This study provides valuable information about the effects of STX and related transcriptional responses in T. japonicus.