Identification of ecdysteroid pathway-related genes and their transcriptional modulation in the brackish water flea Diaphanosoma celebensis exposed to bisphenol analogs

Ecdysone plays a crucial role in the molting process, is synthesized by neverland (nvd) and regulates the transcription of early response genes, HR3 and E75. However, their roles in the development and reproduction of small crustaceans are still poorly understood at the molecular level. Thus, this study aimed to identify and characterize the nvd, HR3, and E75 genes in the brackish water flea Diaphanosomal celebensis, and to investigate their transcriptional modulation upon exposure to bisphenol (BP) analogs. Three genes found in the local D. celebensis transcriptome database were sequenced and identified using BLAST X and conserved domain search. The relative expression patterns of these genes at different ages and under exposure to BP analogs were investigated by real-time reverse transcription polymerase chain reaction. Sequencing analysis showed that nvd, HR3, and E75 had conserved domains. The mRNA expression patterns of Dc-nvd were highly upregulated at day 5 and day 7 of D. celebensis life cycle. The E75 and HR3 mRNA expression patterns differed according to age. The BP analogue exposure test showed that the three genes were significantly modulated with different patterns. The nvd, HR3, and E75 had conserved domains, suggesting that they have conserved functions in D. celebensis. Age-dependent expression of these three genes implies their involvement in the molting cycle. Our findings also suggest that BPS, BPF, and BPA may disrupt the edcysteroid signaling pathway in this species by different mechanisms.