Author(s): Ming-Ming Han, Le-Wang, Li-Na-Peng, Shahidd Mahboob, Khalid A Al-Ghanim, Jian-Guo Lu and Xiao-Wen Sun
Both mannose-binding lectins (MBLs) and ficolins recognize and bind carbohydrates in pathogens and activate complement leading to opsonization, leukocyte activation, and direct pathogen clean. While MBLs have been reported in many fish species, the function of ficolins had not been identified in Pelteobagrus fulvidraco, despite their importance in invertebrate and higher vertebrate innate immunity. Although microfibrillar-associated protein 4 (MFAP4) this protein has similar fibrinogen-like domain, has expression in fish, the role of it has not been dissected. We cloned three MFAP4 genes (1MFAP4, 2MFAP4 and 3MFAP4) from the yellow catfish, P. fulvidraco. The homology similarity of MFAP4 was 78% with Astyanax mexicanus of Cypriniformes. The yellow catfish MFAP4 transcripts expression analysis revealed difference of patterns of homeostatic expression among the genes in gill, blood, muscle, gonad, liver, brain, spleen, kidney, heart, intestine from male and female, respectively. Expression of the three MFAP4 transcripts showed significant expression changes in 4 h after infection with either Edwardsiella ictaluri or Flavobacterium columnare, which has modulation of expression continuing up to 24 h or 7 d following pathogen exposure. Several different tissues and gene-specific patterns were captured and transcript expression changes of >11.45-fold were observed over the course of the bacterial challenges. This information elucidates the functions of individual MFAP4 genes in regards to pathogen recognition, binding, and their larger immune context.
