Sinclair Colleen S, Richmond Robert H, Ostrander Gary K
Department of Biological Sciences, Towson University, Towson, MD 21252, USA.
Genetica. 2007 Mar;129(3):227-33. doi: 10.1007/s10709-006-0001-x. Epub 2006 Aug 1.
Terminal ends of vertebrate chromosomes are protected by tandem repeats of the sequence (TTAGGG). First thought to be vertebrate specific, (TTAGGG)( n ) has recently been identified in several aquatic invertebrates including sea urchin (Strongylocentrotus purpuratus), bay scallop (Argopecten irradians), and wedgeshell clam (Donax trunculus). We analyzed genomic DNA from scleractinian corals, Acropora surculosa, Favia pallida, Leptoria phrygia, and Goniastrea retiformis to determine the telomere sequence. Southern blot analysis suggests the presence of the vertebrate telomere repeats in all four species. Treatment of A. surculosa sperm DNA with Bal31 exonuclease revealed progressive shortening of the DNA fragments positive for the (TTAGGG)(22) sequence, supporting location of the repeats at the chromosome ends. The presence of the vertebrate telomere repeats in corals is evidence that the (TTAGGG)( n ) sequence is highly conserved among a divergent group of vertebrate and invertebrate species. Corals are members of the Lower Metazoans, the group of organisms that span the gap between the fungi and higher metazoans. Corals are the most basal organism reported to have the (TTAGGG)( n ) sequence to date, which suggests that the vertebrate telomere sequence may be much older than previously thought and that corals may share a number of genes with their higher relatives.
脊椎动物染色体的末端由序列（TTAGGG）的串联重复序列保护。（TTAGGG）（n）最初被认为是脊椎动物特有的，最近在几种水生无脊椎动物中被发现，包括海胆（紫海胆）、海湾扇贝（辐条扇贝）和楔形蛤（截形贝）。我们分析了石珊瑚、匐枝鹿角珊瑚、苍白扁脑珊瑚、薄叶蔷薇珊瑚和网纹棘穗珊瑚的基因组DNA，以确定端粒序列。Southern印迹分析表明，所有四个物种中都存在脊椎动物端粒重复序列。用Bal31核酸外切酶处理匐枝鹿角珊瑚精子DNA，显示（TTAGGG）（22）序列阳性的DNA片段逐渐缩短，支持重复序列位于染色体末端。珊瑚中存在脊椎动物端粒重复序列，证明（TTAGGG）（n）序列在不同的脊椎动物和无脊椎动物物种中高度保守。珊瑚是低等后生动物的成员，低等后生动物是一类跨越真菌和高等后生动物之间差距的生物。珊瑚是迄今为止报道的拥有（TTAGGG）（n）序列的最原始生物，这表明脊椎动物端粒序列可能比以前认为的要古老得多，并且珊瑚可能与其高等亲属共享许多基因。
