Identification and analysis of immune-related transcriptome in Asian seabass Lates calcarifer.
BACKGROUND
Fish diseases caused by pathogens are limiting their production and trade, affecting the economy generated by aquaculture. Innate immunity system is the first line of host defense in opposing pathogenic organisms or any other foreign material. For identification of immune-related genes in Asian seabass Lates calcarifer, an important marine foodfish species, we injected bacterial lipopolysaccharide (LPS), a commonly used elicitor of innate immune responses to eight individuals at the age of 35 days post-hatch and applied the suppression subtractive hybridization (SSH) technique to selectively amplify spleen cDNA of differentially expressed genes.


RESULTS
Sequencing and bioinformatic analysis of 3351 ESTs from two SSH libraries yielded 1692 unique transcripts. Of which, 618 transcripts were unknown/novel genes and the remaining 1074 were similar to 743 known genes and 105 unannotated mRNA sequences available in public databases. A total of 161 transcripts were classified to the category "response to stimulus" and 115 to "immune system process". We identified 25 significantly up-regulated genes (including 2 unknown transcripts) and 4 down-regulated genes associated with immune-related processes upon challenge with LPS. Quantitative real-time PCR confirmed the differential expression of these genes after LPS challenge.


CONCLUSIONS
The present study identified 1692 unique transcripts upon LPS challenge for the first time in Asian seabass by using SSH, sequencing and bioinformatic analysis. Some of the identified transcripts are vertebrate homologues and others are hitherto unreported putative defence proteins. The obtained immune-related genes may allow for a better understanding of immunity in Asian seabass, carrying out detailed functional analysis of these genes and developing strategies for efficient immune protection against infections in Asian seabass.
Xia
Jun Hong
JH
Molecular Population Genetics Group, Temasek Life Sciences Laboratory, National University of Singapore, 117604 Republic of Singapore.
Yue
Gen Hua
GH
D000818:Animals; D019295:Computational Biology; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology; D015723:Gene Library; D008070:Lipopolysaccharides / Q000276:immunology; D018895:Microsatellite Repeats / Q000235:genetics; D009693:Nucleic Acid Hybridization; D010473:Perciformes / Q000235:genetics* / Q000276:immunology*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction
D008070:Lipopolysaccharides