The Chinese mitten crab Eriocheir sinensis is an important economic crustacean that has been exposed to various diseases. Spiroplasma eriocheiris, isolated from tremor-diseased E. sinensis, was first identified as a lethal pathogen of freshwater crustaceans. To understand the pathogenesis of S. eriocheiris to E. sinensis,  researchers from Nanjing Normal University obtained the transcriptomic profiles of haemocytes in the experimental and control groups at 1 d and 7 d post-injection using poly(A) RNA-seq service.

Results showed that 40,358,724, 44,462,112, 45,516,576 and 37,713,728 paired-end clean reads were obtained from the cDNA libraries of DZ1 (the control group at 1 d), DZ7 (the control group at 7 d), SY1 (the experimental group at 1 d) and SY7 (the experimental group at 7 d), respectively. In total, 106,641 unique transcript fragments (unigenes) were assembled, with an average length of 710 bp. On the first day of stimulation, 33,084 up-regulated transcripts and 19,208 down-regulated transcripts were found in the experimental group compared with those in the control group. On the seventh day of stimulation, 40,198 up-regulated transcripts and 12,032 down-regulated transcripts were found in the experimental group compared with those in the control group.

 

Overview of differently expressed gene distribution trends between the (A) SY1 and DZ1 or (B) SY7 and DZ7 group. The x-axis represents the gene expression quantities (in logs) of the control group, and the y-axis represents the gene expression quantities of the experimental group.

Some canonical immune-related pathways were identified via KEGG pathway analysis, including complement and coagulation cascades, the VEGF signalling pathway, the Wnt signalling pathway, natural killer cell-mediated cytotoxicity, the MAPK signalling pathway, neuroactive ligand-receptor interactions, and the Lysosome pathway. Researchers found important immune-related genes (GNPTAB, MASP2, F7, F5, NFATC, TRAF6, MAP3K5, and TRa) in the KEGG pathway, and those genes were confirmed by qRT-PCR analysis. In addition, the significantly enriched neuroactive ligand-receptor interaction pathway was associated with intense paroxysmal tremors of infected crabs.

These results provide valuable information for the further analysis of the mechanisms of E. sinensis defence against S. eriocheiris invasion.

 

Reference
Y. Wang, Y. Xiu, K. Bi, J. Ou, W. Gu, W. Wang, Q. Meng (2017) Integrated analysis of mRNA-seq in the haemocytes of Eriocheir sinensis in response to Spiroplasma eriocheiris infection Fish & Shell Immunol. doi: 10.1016/j.fsi.2017.07.036 [abstract]

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