Walter M F, Bozorgnia L, Maheshwari A, Biessmann H
Developmental Biology Center, University of California, Irvine, CA 92697, USA.
Insect Mol Biol. 2001 Feb;10(1):105-10. doi: 10.1046/j.1365-2583.2001.00245.x.
Using a single copy pUChsneo transgene insertion at the Anopheles gambiae 2L telomere, this chromosome end was monitored by genomic Southern blots for forty-four mosquito generations. During this time, the chromosome end lost terminal nucleotides at an apparently constant rate of 55 bp/generation, which can be accounted for by incomplete DNA replication and does not imply exonuclease activity. No telomere elongation events were detected, suggesting that a previously described gene conversion event at this transgene does not occur very frequently. Moreover, no evidence for elongation by transposable elements was found, as described in Drosophila melanogaster. These results are consistent with the proposal that gene conversion between complex terminal satellite repeats that are present at natural telomeres, represents the major telomere elongation mechanism in A. gambiae. Such recombination events between repetitive sequences would occur more frequently than between the single copy pUChsneo transgene on the 2L homologues.
利用在冈比亚按蚊2L端粒处插入的单拷贝pUChsneo转基因，通过基因组Southern印迹法对该染色体末端进行了44代蚊子的监测。在此期间，染色体末端以55 bp/代的明显恒定速率丢失末端核苷酸，这可由不完全DNA复制来解释，并不意味着存在核酸外切酶活性。未检测到端粒延长事件，这表明之前描述的该转基因处的基因转换事件并不经常发生。此外，未发现如在黑腹果蝇中所描述的可转座元件导致延长的证据。这些结果与以下提议一致，即天然端粒处存在的复杂末端卫星重复序列之间的基因转换是冈比亚按蚊主要的端粒延长机制。重复序列之间的这种重组事件比2L同源染色体上的单拷贝pUChsneo转基因之间的重组事件更频繁发生。
