Doublesex and mab-3 related transcription factor (dmrt) play crucial roles in sex determination and sex differentiation in vertebrates and invertebrates. Although dmrt genes have been identified in vertebrates, little is known about aquatic invertebrates. In this study, two dmrt genes, namely, Dc_dmrt93B and Dc_dmrt99B, were identified from brackish water flea, Diaphanosoma celebensis. Transcriptional changes were observed in the dmrt genes when the flea was exposed to bisphenol (BP), an endocrine disruptor. Sequence and phylogenetic analyses showed that both dmrt genes contained two conserved domains, namely, DM and DMA, closely clustered with those of Daphnia spp. Additionally, a significant increase in the Dc_dmrt99B mRNA expression level was observed upon exposure to intermediate concentrations of BP (bisphenol A>bisphenol S=bisphenol F, p<0.05), while the expression of Dc_dmrt93B mRNA was slightly modulated. These findings imply that the two dmrt genes may be involved in sex differentiation of D. celebensis. Furthermore, it was found that the ability of BP to modulate dmrt genes could affect development and reproduction. This study provides a basis for understanding the function of the dmrt genes and the molecular mode of action of BP in small crustaceans.

Abstract
INTRODUCTION
MATERIALS AND METHODS
    1. Experimental organism and culturemaintenance
    2. Reagents
    3. Exposure test
    4. Total RNA extraction and cDNA synthesis
    5. Polymerase chain reaction (PCR)
    6. Phylogenetic analysis
    7. Quantitative real time - polymerase chainreaction (qRT-PCR)
    8. Statistical analysis
RESULTS AND DISCUSSION
    1. Sequence analysis and phylogeneticrelationship of D. celebensis dmrt93B anddmrt99B
    2. Transcriptional modulation ofD. celebensis dmrt93B and dmrt99Bafter exposure to BP analogs
REFERENCES

• Hayoung Cho(Department of Biotechnology, College of Convergence Engineering, Sangmyung University)
• Min Jeong Jeon(Department of Biotechnology, College of Convergence Engineering, Sangmyung University)
• Young-Mi Lee(Department of Biotechnology, College of Convergence Engineering, Sangmyung University) Corresponding author