Lee Kwang-Zin, Sommer Ralf J
Max-Planck Institut für Entwicklungsbiologie, Abteilung für Evolutionsbiologie, Tübingen, Germany.
Mol Biol Evol. 2003 Dec;20(12):2097-103. doi: 10.1093/molbev/msg225. Epub 2003 Aug 29.
In the nematode Caenorhabditis elegans, up to 15% of the genes are organized in operons. Polycistronic precursor RNAs are processed by trans-splicing at the 5' ends of genes by adding a specific trans-spliced leader. Ten different spliced leaders are known in C. elegans that differ in sequence and abundance. The SL1 leader is most abundant and is spliced to the 5' ends of monocistronic genes and to upstream genes in operons. Trans-splicing is common among nematodes and was observed in the genera Panagrellus, Ascaris, Haemonchus, Anisakis, and Brugia. However, little is known about operons in nonrhabditid nematodes. Dolichorhabditis CEW1, another rhabditid nematode that is now called Oscheius CEW1, contains operons and SL2 trans-splicing. We have studied the presence of operons and trans-splicing in Pristionchus pacificus, a species of the Diplogastridae that has recently been developed as a satellite organism in evolutionary developmental biology. We provide evidence that P. pacificus contains operons and that downstream genes are trans-spliced to SL2. Surprisingly, the one operon analyzed so far in P. pacificus is not conserved in C. elegans, suggesting unexpected genomic plasticity.
在线虫秀丽隐杆线虫中，高达15%的基因以操纵子形式组织。多顺反子前体RNA通过在基因的5'端进行反式剪接来加工，即添加一个特定的反式剪接前导序列。秀丽隐杆线虫中已知有10种不同的剪接前导序列，它们在序列和丰度上有所不同。SL1前导序列最为丰富，它被剪接到单顺反子基因的5'端以及操纵子中的上游基因。反式剪接在线虫中很常见，在杆线虫属、蛔虫属、血矛线虫属、异尖线虫属和布鲁格丝虫属中都有观察到。然而，关于非杆线虫类线虫中的操纵子知之甚少。多氏杆线虫CEW1，现在称为奥氏杆线虫CEW1，另一种杆线虫类线虫，含有操纵子和SL2反式剪接。我们研究了太平洋小杆线虫中操纵子和反式剪接的存在情况，太平洋小杆线虫是双胃线虫科的一个物种，最近已被开发成为进化发育生物学中的一种附属生物。我们提供的证据表明，太平洋小杆线虫含有操纵子，并且下游基因被反式剪接到SL2。令人惊讶的是，到目前为止在太平洋小杆线虫中分析的一个操纵子在秀丽隐杆线虫中并不保守，这表明存在意想不到的基因组可塑性。
