Genetic relationships among hippopotamus, whales, and bovine based on SINE insertion analysis

• Published in: Mammalian genome Vol. 10; no. 5; pp. 526 - 527
• Main Authors: Nomura, O, Yasue, H
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01.05.1999
• Subjects: Animals; Artiodactyla; Artiodactyla - genetics; Balaenoptera physalus; Bos taurus; Cattle; Cetacea; Cetacea - genetics; Globicephala macrorhynchus; Hippopotamus amphibius; Marine; Nucleic Acid Hybridization; Phylogeny; Short Interspersed Nucleotide Elements; Species Specificity; Tursiops truncatus
• ISSN: 0938-8990; 1432-1777
• DOI: 10.1007/s003359901035

Since genetic linkage between cetaceans and ungulates was first proposed, it has been a subject of considerable discussion for nearly a century without a consensus. Recently, a strong genetic linkage between cetaceans and hippopotamid artiodactyls was proposed for the first time from the standpoint of molecular level analysis by comparison of nucleotide sequences, including milk casein genes (Gatesy et al. 1996; Irwin and Arnason 1994). Our previous study revealed that cetaceans contained sequences homologous to a short interspersed repetitive element (SINE) of hippopotamus, CHR-2(hippo), more abundant than in any other species of Artiodactyla, and thus supporting the linkage (Nomura et al. 1998). On the other hand, when a maximum likelihood method was applied on the sequence comparison, it turned out not to support the linkage (Hasegawa and Adachi 1996). More recently, Shimamura et al. (1997) clearly demonstrated that cetaceans formed a clade with ruminants and hippopotamus, by analyzing insertion of a cetacean SINE, CHR-1, into the genomes of ruminants and hippopotamus. However, the analysis was incapable of distinguishing the order of species separation among them. In the present study, we examined whether or not CHR-2 (hippo) homologous sequences existed at the corresponding loci of cetaceans and bovine genomes. Primer sets were designed for both flanks of the CHR-2 (hippo) sequences so as to amplify locus-specific fragments in the polymerase chain reaction (PCR) using genomic DNA as a template. PCR was performed with the respective primer sets and using Balaenoptera physalus (fin whale), Tursiops truncatus (bottle-nosed dolphin), Globicephala macrorhynchus (short-finned pilot whale), Hippopotamus amphibius (hippopotamus), and Bos taurus (bovine) genomic DNAs (50 ng) as a template. Balaenoptera physalus (fin whale) and Globicephala macrorhynchus (short-finned pilot whale) genomic DNAs were donated from the Central Customs Laboratory (Chiba, Japan); and Tursiops truncatus (bottle-nosed dolphin), Hippopotamus amphibius (hippopotamus), and Bos taurus (bovine) genomic DNAs were those used in our previous study (Nomura et al. 1998).