Li Huan, Li Yujin, Zhang Xiaoping, Wang Yafeng, Zhang Wufeng, Wu Xia, Wang Zhijian
Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of Ministry of Education, School of Life Sciences, Southwest University, No. 1 Tiansheng Road, Beibei district, Chongqing, 400715, China.
Key Laboratory of Freshwater Fish Reproduction Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, 400715, China.
Fish Physiol Biochem. 2017 Dec;43(6):1571-1585. doi: 10.1007/s10695-017-0394-8. Epub 2017 Jun 25.
CD79a and CD79b heterodimers are the important signaling components of B cell receptor (BCR) complex which plays a crucial role in B cell development and antibody production. In the present study, CD79a and CD79b homologues from Chinese sucker (Myxocyprinus asiaticus), namely MaCD79a and MaCD79b, were identified and their expression at early developmental stages and under constitutive and stimulated conditions were investigated. The cDNA sequences for MaCD79a and MaCD79b contained open reading frame of 678 and 636 bp in length for 225 and 211 amino acid residues, respectively. The conserved features and important functional residues were found by sequence analysis. RT-PCR analysis revealed that transcripts of MaCD79s were detected in eggs and hatchling at 1-3 and 5-11 days post hatching (dph), but not detected at 13-17 and 19-27 dph, and constantly detected from 30 dph. Tissue distribution analysis showed that MaCD79s was most highly expressed in immune tissues, such as the spleen, head kidney, and kidney; the relatively low levels were detected in the heart, gill, and liver. Results of in situ hybridization also confirmed that MaCD79s is mainly expressed in systematic immune organs. Meanwhile, similar to IgM, MaCD79s-expressing cells in mucosal immune organ including the digestive track and gill were observed. Additionally, significant upregulation of MaCD79s was seen in the head kidney and spleen of Chinese sucker injected with Aeromonas hydrophila by quantitative real-time PCR. Taken together, our findings provided further information regarding fish CD79s gene and its role in adaptive immunity, which will contribute to the preservation and aquaculture of Chinese sucker.
CD79a和CD79b异二聚体是B细胞受体（BCR）复合物的重要信号成分，在B细胞发育和抗体产生中起关键作用。在本研究中，鉴定了中华倒刺鲃（Myxocyprinus asiaticus）的CD79a和CD79b同源物，即MaCD79a和MaCD79b，并研究了它们在早期发育阶段以及组成型和刺激条件下的表达。MaCD79a和MaCD79b的cDNA序列分别包含长度为678和636 bp的开放阅读框，分别编码225和211个氨基酸残基。通过序列分析发现了保守特征和重要的功能残基。RT-PCR分析显示，在孵化后1-3天和5-11天的卵和幼体中检测到MaCD79s的转录本，但在13-17天和19-27天未检测到，从30天开始持续检测到。组织分布分析表明，MaCD79s在免疫组织如脾脏、头肾和肾脏中表达最高；在心脏、鳃和肝脏中检测到的水平相对较低。原位杂交结果也证实MaCD79s主要在系统性免疫器官中表达。同时，与IgM类似，在包括消化道和鳃在内的黏膜免疫器官中观察到表达MaCD79s的细胞。此外，通过定量实时PCR在注射嗜水气单胞菌的中华倒刺鲃的头肾和脾脏中观察到MaCD79s显著上调。综上所述，我们的研究结果提供了关于鱼类CD79s基因及其在适应性免疫中的作用的进一步信息，这将有助于中华倒刺鲃的保护和养殖。
