Borges B N, Paiva T S, Harada M L
Laboratório de Biologia Molecular "Francisco Mauro Salzano", Instituto de Ciências Biológicas, Universidade Federal do Pará, Cidade Universitária Prof. José da Silveira Netto, Belém, PA, Brasil.
Genet Mol Res. 2008 Jul 29;7(3):663-78. doi: 10.4238/vol7-3gmr452.
The structure and evolution of the SEC1 gene were examined for the first time in New World primates of the genera Alouatta, Aotus, Ateles, Brachyteles, Callicebus, Callithrix, Cebus, Chiropotes, Lagothrix, Leontopithecus, Pithecia, Saguinus, and Saimiri. This gene has a high CG content (63.8%) and an estimated heterogeneous size ranging from 795 (Callithrix) to 1041 bp (Pithecia), due to numerous indel events. Similar to other fucosyltransferases, three conserved regions are shared by these primates, except for the callitrichines, Aotus and Pithecia, in which indel events resulted in premature stop codons that are related to the production of a supposedly non-functional protein. Phylogenetic analysis of the SEC1 gene, transition/transversion rates, and nucleotide sequence alignment support the hypothesis that primate SEC1 evolved by divergent evolution, and that the lack of activity in some lineages occurred independently at least twice in New World primates, once in the Aotus-Cebus-Callitrichinae group and again in Pithecia. Likelihood-based inference of ancestral states for the activity of SEC1 leads us to suppose that inactivation of SEC1 in the Callitrichinae was a result of a more complex series of events than in Pithecia.
首次在蛛猴属、夜猴属、蜘蛛猴属、绒毛蛛猴属、伶猴属、狨属、卷尾猴属、节尾猴属、绒毛猴属、狮面狨属、猴面狨属、柽柳猴属和松鼠猴属等新大陆灵长类动物中研究了SEC1基因的结构和进化。由于存在大量插入/缺失事件，该基因具有较高的CG含量（63.8%），估计大小不均一，范围从795bp（狨属）到1041bp（猴面狨属）。与其他岩藻糖基转移酶类似，除了狨科、夜猴属和猴面狨属外，这些灵长类动物共有三个保守区域，在狨科、夜猴属和猴面狨属中，插入/缺失事件导致了提前终止密码子，这与一种推测无功能蛋白质的产生有关。SEC1基因的系统发育分析、转换/颠换率和核苷酸序列比对支持了这样的假设：灵长类动物的SEC1是通过趋异进化演化而来的，并且在新大陆灵长类动物中，某些谱系缺乏活性至少独立发生了两次，一次在夜猴属 - 卷尾猴属 - 狨科动物组中，另一次在猴面狨属中。基于似然性对SEC1活性的祖先状态进行推断，使我们推测狨科动物中SEC1的失活是一系列比猴面狨属中更复杂事件的结果。
