Transthyretin Intron 1 based Interordinal Relationships of Laurasiatheria

Abstract

Transthyretin (TTR), a major thyroid hormone distributor protein (THDP) in the blood, is coded by a gene which contains four exons and three introns. Nowadays, several nuclear gene introns have been successfully utilized to elucidate the relationships of organisms, including TTR intron 1 nucleotide sequence. In this study, the utilization of TTR intron 1 to resolve the interrelatedness of mammals in Laurasiatheria was explored. The complete TTR intron 1 sequences from 36 animal species including human (Homo sapiens) were extracted from the genome sequences retrieved from the GenBank. In addition, the sequences from two microbats e.g. intermediat horseshoe bat (Rhinolophus affinis) and lesser Asiatic yellow house bat (Scotophilus kuhlii) were amplified by PCR and sequenced. The phylogenetic relationship of the studied animals was analyzed using MEGA 6 program. Based on the TTR intron 1, the phylogenetic tree with most of major nodes was strongly supported by bootstrap >75% was successfully produced. The monophyletic relationships within each order were strongly supported, ranging from 67% (within Eulipotyphla) to 100% (within Cetratiodactyla and Carnivora) bootstrap. However, the placement of Perissodactyla as the sister group to Carnivora was supported at low bootstrap. The paraphyletic relationships of the members within Chiroptera was highly supported with >85% bootstrap. In addition, more closely relatedness of the microbat R. affinis to the megabats than to the other microbats was supported with 97% bootstrap. The results presented here indicated to the usefulness of TTR intron 1 in resolving the relationships of the animals in Laurasiatheria.