斑节对虾基因组微卫星分离及其序列特征研究

采用(CA)_(12)(AG)_(12)及(TA)_(16)生物素标记探针及磁珠富集法构建了斑节对虾Penaeus monodon基因组微卫星富集文库。随机挑选254个克隆进行PCR筛选,得到51个候选克隆(20．1%)。其中,32个克隆来源于CA-文库,另19个克隆来源于AG-文库。测序发现48个克隆含有微卫星重复单元,通过序列比对,最终获得40个具有特异微卫星序列的阳性克隆。微卫星(GA/CT)_N及(CA/GT)_n 2碱基重复序列分别占所有分离的微卫星数目的20．7%及60．4%。此外,还检测到其它多种微卫星重复类型,如(AT)_n、(GC)_n、(TGG)_n、(AAG)_n、(AAT)_n、(GAA)_n、(GTGC)_n、(GCGT)_n、(GGTTA)_n、(GTGCGT)_n,占检测到的微卫星数目的18．9%。获得的微卫星序列中属于完全型序列的有76条(68．5%),不完全型序列的有22条(19．8%),另有13条属于复合型序列(11．7%)。微卫星(GT/CA)_n 2碱基重复次数(3～52次)要远大于(GA/CT)_n 2碱基次数(3～27次)。获得的微卫星序列长度大小范围为129～601 bp,平均为286 bp。研究为进一步开展斑节对虾分子育种及资源评价分析提供了基础资料。

Isolation and characterization of microsatellites from the tiger shrimp Penaeus monodon

Microsatellite-enhanced genomic library of the tiger shrimp Penaeus monodon was constructed using repeat-enrichment meth- od with biotin-labeled oligos(CA)_(12),(AG)_(12)and(TA)_(16)]and streptavidin magnetic beads.From a total of randomly selected 254 clones,51 clones(20.1%)were positive after PCR selection.Of which,32 clones comes from(CA)_(12)probe-used library,the left from(AG)_(12)probe-used library.48 clones are discovered to contain microsatellites.By alignment,40 special microsatellite clones are confirmed finally.(GA)_n and(CA)_n were the abundant microsatellite motifs with a percentage of 20.7% and 60.4% in the isolated microsatellites.Several other types of repeat sequences were detected,including repeats consisting of(AT)_n,(GC)_n,(TGG)_n, (AAG)_n,(AAT)_n,(GAA)_n,(GTGC)_n,(GCGT)_n,(GGTTA)_n,(GTGCGT)_n making up to 18.9%.Characterization of these microsatellites showed that 76(68.5%)sequences were classified as perfect type,22(19.8%)as imperfect type and 13(11.7%) as compound type.The repeat units of(GT/CA)_n ranged from 3 to 52 was much more than the units of(GA/CT)_n ranged from 3 to 27.The sequence size ranges from 129 to 601 bp with an average of 286 bp.This study provides a base for molecular breeding and as- sessment of germplasm resources of the tiger shrimp in future.