中华绒螯蟹（Eriocheir japonica sinensis）内转录间隔区1（ITS1）大小变异的研究

在对中华绒螯蟹（Eriocheir japonica sinensis）（又称河蟹）核糖体DNA内转录间隔区1（ITS1）进行研究时，由于在软甲亚纲中还没有已知序列和5.8SrDNA 序列的报道，所以在设计引物时，主要参考了其它节肢动物的序列。用此引物对河蟹的ITS1 进行扩增，发现其个体内的ITS1如同其它一些无脊椎动物一样，存在大小变异。为了进一步确证这发现，首先将得到的所有扩增产物进行测序，然后再扩增出河蟹的整个ITS区并测序。通过所得序列的比较，发现河蟹个体内ITS1的大小变异是有引物错配而引起的赝相。为了检验这一理论的可靠性，该文在测出河蟹5.8SrDNA 序列的基础上，重新设计了引物，并再次扩增了河蟹的ITS1，然后对产物进行测序，最后再同上述结果进行比较；同事在改变扩增条件的情况下用原引物重新扩增ITS1，并检验其结果。最终证实河蟹个体内ITS1的大小变异是由引物错配而引起的赝相。该文同时还报道了中华绒螯蟹ITS1的序列。

Study on Size Variation of rDNA Internal Transcribed Spacer 1 in Eriocheir japonica sinensis (Decapoda,Grapsidae)

The intra-individual size variation of rDNA ITS1 (first internal transcribed spacer of rDNA) was detected in some invertebrates, such as Schistoaoma japonicum, Paragonimus westermani, Simulium. In our experiment of investigating the primary structure of ITS1 of Eriocheir japonica. sinensis the intra-individual size polymorphism was detemined at first, but further study showed that the polymorphism was an artifact,which was due to PCR primers mismatching.This conclusion was finally demonstrated by verifying conditions of PCR and reamplifying the ITS1 domain using redesigning primer that was corresponding to 5.8S rDNA sequences of E. japonica. sinensis that obtained in this study. The nucleotide sequence of the ITS1 of E.japonica sinensis has been firstly determined in this species.