Genomic organisation and expression of the natural killer cell enhancing factor (NKEF) gene in channel catfish, Ictalurus punctatus (Rafinesque)

• Published in: Fish & shellfish immunology 2006, Vol.20 (1), p.72-82
• Main Authors: Li, Robert W., Waldbieser, Geoffrey C.
• Format: Article
• Language: English
• Subjects: alleles; Amino Acid Sequence; amino acid sequences; animal proteins; animal tissues; Animals; Bacteria; Base Sequence; blood cells; Blood Proteins - genetics; Catfish; chromosome mapping; Cluster Analysis; complementary DNA; Cytotoxicity, Immunologic - genetics; DNA Primers; DNA, Complementary - genetics; Escherichia coli; exons; Freshwater; Gene Expression; genes; Genetic Linkage; genetic polymorphism; Genome - genetics; Ictaluridae - genetics; Ictaluridae - immunology; Ictalurus punctatus; immune response; immunity; introns; Lipopolysaccharides; LPS; messenger RNA; Microsatellite Repeats - genetics; Molecular Sequence Data; natural killer cell enhancing factor; NKEF; nucleotide sequences; Phylogeny; promoter regions; Reverse Transcriptase Polymerase Chain Reaction; Sequence Analysis, DNA
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2005.04.002

The gene encoding Natural Killer Cell Enhancing Factor (NKEF) was identified in clones from a gynogenetic channel catfish BAC library. NKEF gene sequence (5.2 kb) was obtained by direct sequencing of BAC clones. The catfish NKEF gene contains one non-coding exon, five coding exons and five introns. A putative TATA box and other transcription factor binding sites were identified in the promoter region. The NKEF amino acid sequence is highly conserved between fish and mammals. Gene expression, measured by real-time quantitative PCR, was detected in all major tissues with the highest level of expression in stomach and heart and lowest levels in gonad and pituitary gland. Catfish NKEF mRNA levels were slightly upregulated 8 and 24 h after injection of lipopolysaccharide. A TAA-repeat microsatellite was identified in a BAC clone containing the NKEF gene, and this locus contained at least 12 alleles in a random-bred catfish population. Multipoint linkage analysis in two reference families placed the NKEF gene on linkage group U18, 5.1 cM from locus IpCG0177 ( r = 0.05; LOD = 45.8), 6.0 cM from a novel immune type receptor, syntenic (40 cM) with T-cell receptor α, and not linked with MHC loci.