Identification of three doublesex genes in the monogonont rotifer Brachionus koreanus and their transcriptional responses toenvironmental stressor-triggered population growth retardation

Abstract

Doublesex and Mab-3-related transcription factor (Dmrt) gene family members have rarely been identified or characterized in aquatic invertebrates. In this study, we identified and characterized three DMdomain-containing genes- Dmrt11E, Dmrt93B, and Dmrt99B- in themonogonont rotifer, <em>Brachionus koreanus</em>. DMdomains of the proteins encoded by the <em>B. koreanus Dmrt</em> (Bk-Dmrt) genes had high similarities to DM domains of other invertebrate species. To understand the potential effects of environmental stressors on the transcriptional expression of Dmrt genes in rotifers, we exposed <em>B. koreanus</em> to a wide range of UV-B radiation and different concentrations of benzo [a]pyrene (B[a]P) over different time courses. Transcript levels of all Bk-Dmrt genes decreased significantly in response to relatively high doses of UV-B irradiation, and were also downregulated in response to exposure to UV-B radiation over time. Transcript levels of all Bk-Dmrt genes were downregulated in response to B[a]P exposure for 24 h. This decrease in expression of all Bk-Dmrt genes was concomitant with the growth retardation induced by UV-B and B[a]P exposure. We concluded that both environmental stressors have detrimental effects on transcriptional regulation of all Bk-Dmrt genes, especially relatively high doses of these stressors, leading to growth retardation. However, further studies are required to better understand the potential role of Dmrt genes in environmental stressor-triggered growth retardation in the rotifer <em>B. koreanus</em>.