[The distribution and origin of P elements in Drosophila melanogaster strains from northeast China]

Eukaryotic transposable elements, especially P transposable elements of Drosophla, are very important to study the evolution of biology. We collected 130 single--female lines of D. melanogaster from 13 places in Northeast China and 3 places nearby which are Beijing(BC), Yantai (YT), Huhehaote(HHT) in 1999 and 2000. We amplified the fragments from ORF2 to ORF3 of P elements using PCR and calculated the defective frequencies and defective parameters of P elements from different places. Basing on the distribution of defective P elements, we suggested the invasion route of P elements of D. melanogaster in Northeast China. The results indicate that the defective frequencies decrease from the frontier to the inland, and in the isolated places the frequencies are lower. It is proposed that P elements of D. melanogaster in Northeast China originate from Korea and Russia to the frontiers of P.R. China, then expand into the inland.