Li Robert W, Waldbieser Geoffrey C
USDA, Agricultural Research Service, Catfish Genetics Research Unit, Stoneville, MS 38776, USA.
Fish Shellfish Immunol. 2006 Jan;20(1):72-82. 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 alpha, and not linked with MHC loci.
在雌核发育斑点叉尾鮰细菌人工染色体（BAC）文库的克隆中鉴定出了编码自然杀伤细胞增强因子（NKEF）的基因。通过对BAC克隆进行直接测序获得了NKEF基因序列（5.2 kb）。斑点叉尾鮰NKEF基因包含一个非编码外显子、五个编码外显子和五个内含子。在启动子区域鉴定出一个推定的TATA盒和其他转录因子结合位点。NKEF氨基酸序列在鱼类和哺乳动物之间高度保守。通过实时定量PCR测量基因表达，在所有主要组织中均检测到表达，其中胃和心脏中的表达水平最高，性腺和垂体中的表达水平最低。注射脂多糖后8小时和24小时，斑点叉尾鮰NKEF mRNA水平略有上调。在包含NKEF基因的BAC克隆中鉴定出一个TAA重复微卫星，并且该位点在一个随机繁殖的斑点叉尾鮰群体中包含至少12个等位基因。在两个参考家系中的多点连锁分析将NKEF基因定位在连锁群U18上，距离IpCG0177位点5.1 cM（r = 0.05；LOD = 45.8），距离一种新型免疫型受体6.0 cM，与T细胞受体α同线（40 cM），且与MHC位点不连锁。
