Transcriptome Analysis of Immune-Related Gene in Hybrid Yellow Catfish in Reaction to Peptidoglycan Challenge

Abstract

Hybrid yellow catfish (<i>Tachysurus vachelli x Tachysurus fulvidraco</i>) is one of the most important freshwater fish in China, intensive culturing has caused increased susceptibility to bacteria, viruses, and parasites. However, little is known about its adaptation mechanisms to pathogen infection. To better understand its immune system and immune related gene under pathogen infection, the transcriptome was analyzed by comparing the data of hybrid yellow catfish spleen stimulated by PGN and PBS. Fish in experimental group were injected with 100 μl baccilus subminis PGN (1mg/ml, 69,554, Sigma) intraperitoneally, and the fish in control group injected with 100 ul phosphate buffered solution (PBS). After 24 h injection, spleens were collected and immediately frozen in liquid nitrogen, then stored in -80°C refrigerator. Total RNA from spleens of hybrid yellow catfish were extracted using Trizol reagent (Sangon, China) according to the manufacturer’s instructions. The libraries were constructed using TruSeq Stranded mRNA LT Sample Prep Kit (Illumina, USA) and sequenced on an Illumina HiSeq X Ten platform. There were 285 differentially expressed genes (DEGs) between PGN treated experimental groups and PBS control groups at 24 h, including 213 up regulated and 72 down regulated DEGs. The expression of qRT-PCR from five up regulated DEGs and five down regulated DEGs were consistent with RNA-Seq. In the analysis of GO enrichment, DEGs in the spleens of PGN treated hybrid yellow catfish were significantly enriched in GO items, including Biological Process, Cellular Component, and Molecular Function items. The identified DEGs and enriched GO terms and KEGG pathways were useful for understanding the physical and biochemical performances, and the transcriptome data greatly enriched the genetic information of hybrid yellow catfish.