Rel/nuclear factor (NF)-κB family of transcription factors paly vital roles in innate immunity response to bacterial and viral infection. Here, we cloned and identified a dorsal homologue (named as MnDorsal) from Macrobrachium nipponense. The full-length cDNA of MnDorsal is 2573 bp with a 1986 bp open reading frame that encodes 661 amino acids. Predicted MnDorsal protein contained a RHD (Rel homology domain), an IPT (Iglike, plexins, and transcriptions factors) domain, and two low complexity regions. Phylogenetic analysis showed that MnDorsal has a closer genetic distance with dorsal homologues from invertebrates. MnDorsal was widely expressed in a variety of tissues, including hemocytes, heart, hepatopancreas, gills, stomach, and intestine. Expression patterns analysis showed that the transcriptional level of MnDorsal in the gills was evidently up-regulated after Staphylococcus aureus, Vibrio parahaemolyticus, white spot syndrome virus, or polyinosinic-polycytidylic acid challenge, suggesting that MnDorsal participates in the immune defenses against pathogens and stimulant challenges. Additionally, the dsRNA-mediated RNA interference analysis showed that knockdown of MnDorsal can significantly inhibit the expression of anti-lipopolysaccharide factor (ALF) and crustin. Further studies revealed that the up-regulated expression of ALFs (MnALF2, MnALF3, and MnALF4) and crustins (MnCrustin3 and MnCrustin4) caused by S. aureus infection were obviously decreased after silencing MnDorsal. These findings suggest that MnDorsal positively regulate the expression of antibacterial peptides (AMPs) during S. aureus infection. Our study will promote to better understand the role of Toll-Dorsal-AMPs pathway in innate immunity response to gram-positive bacterial infection in crustacean.

Rel /核因子（NF）-κB家族转录因子在对细菌和病毒感染的天然免疫应答中起着至关重要的作用。在这里，我们从日本沼虾（Macrobrachium nipponense）克隆并鉴定了背侧同源物（命名为MnDorsal）。MnDorsal的全长cDNA为2573 bp，带有一个1986 bp的开放阅读框，编码661个氨基酸。预测的MnDorsal蛋白包含RHD（Rel同源结构域），IPT（Iglike，plexins和转录因子）结构域和两个低复杂性区域。系统发育分析表明，MnDorsal与无脊椎动物背侧同源物之间的遗传距离更近。锰背在血细胞，心脏，肝胰腺、,、胃和肠等各种组织中广泛表达。表达模式分析表明，在金黄色葡萄球菌，副溶血性弧菌，白斑综合症病毒或多肌苷酸-聚胞苷酸攻击后，the中的MnDorsal转录水平明显上调，这表明MnDorsal参与了针对病原体和刺激物的免疫防御。 。此外，dsRNA介导的RNA干扰分析表明MnDorsal的敲低可以显着抑制抗脂多糖因子（ALF）和Crustin的表达。进一步的研究表明，沉默MnDorsal后，由金黄色葡萄球菌感染引起的ALFs（MnALF2，MnALF3和MnALF4）和结蛋白（MnCrustin3和MnCrustin4）的上调表达明显降低。这些发现表明，MnDorsal在金黄色葡萄球菌感染过程中正调节抗菌肽（AMPs）的表达。我们的研究将促进更好地了解Toll-Dorsal-AMPs途径在甲壳类动物对革兰氏阳性细菌感染的天然免疫应答中的作用。