Institute of Zoology, Department of Life Science, National Taiwan University, Taipei, Taiwan.
Theriogenology. 2011 Jan 1;75(1):55-64. doi: 10.1016/j.theriogenology.2010.07.010. Epub 2010 Aug 23.
The systematic status of Pholidota has been a matter of debate, particularly regarding the apparent inconsistency between morphological and molecular studies. The Sry gene, a master regulator of male sex determination in eutherian mammals, has not yet been used for phylogenetic analyses of extant mammals. The objective of the present study was to clone and characterize the complete gene (1300 base pairs; bp) and amino acid sequences (229 residues) of Sry from the Formosan pangolin (Manis pentadactyla pentadactyla), a member of Pholidota. The Sry amino acid identity between pangolin and other reported species ranged from 42.5% (mouse, Mus musculus) to 84.1% (European hare, Lepus europaeus). Sequence conservation was primarily in the high motility group (HMG) box (234 bp), whereas homology outside the HMG box was low. The cloned Sry was mapped to the pangolin Y chromosome by fluorescence in situ hybridization (FISH); this was confirmed to be the first Y-borne molecular marker identified in Pholidota. Based on Bayesian phylogenetic analysis for Sry HMG sequences from 36 representative taxa, including the Formosan pangolin, Pholidota was more closely related to Carnivora than to Xenarthra, consistent with the emerging molecular tree inferred from markers not located on the Y chromosome. In conclusion, this study characterized the gene structure of Sry of the Formosan pangolin and provided insights into the phylogenetic position of Pholidota.
穿山甲的系统地位一直存在争议，特别是在形态学和分子研究之间明显不一致的情况下。Sry 基因是真兽类哺乳动物雄性性别决定的主要调节因子，尚未用于现存哺乳动物的系统发育分析。本研究的目的是从穿山甲（Manis pentadactyla pentadactyla）中克隆和鉴定 Sry 基因（1300 个碱基对；bp）和完整的氨基酸序列（229 个残基）。穿山甲和其他报道物种的 Sry 氨基酸同一性在 42.5%（小鼠，Mus musculus）至 84.1%（欧洲野兔，Lepus europaeus）之间。序列保守性主要在高迁移率组（HMG）盒（234 bp）中，而 HMG 盒外的同源性较低。通过荧光原位杂交（FISH）将克隆的 Sry 定位到穿山甲的 Y 染色体上；这被证实是首次在鳞甲目动物中鉴定出的 Y 染色体携带的分子标记。基于来自 36 个代表性分类群（包括台湾穿山甲）的 Sry HMG 序列的贝叶斯系统发育分析，鳞甲目动物与食肉目动物的亲缘关系比与有袋目动物的亲缘关系更密切，这与不位于 Y 染色体上的标记推断出的新兴分子树一致。总之，本研究对台湾穿山甲的 Sry 基因结构进行了特征描述，并为鳞甲目动物的系统发育位置提供了新的见解。
