Widespread Divergence of the CEACAM/PSG Genes in Vertebrates and Humans Suggests Sensitivity to Selection

Chang, Chia Lin; Semyonov, Jenia; Cheng, Po Jen; Huang, Shang Yu; Park, Jae Il; Tsai, Huai-Jen; Lin, Cheng-Yung; Grützner, Frank; Soong, Yung Kuei; Cai, James J.; Hsu, Sheau Yu Teddy

Chromosomal localization of CEACAM family genes was obtained from the NCBI database. Syntenic maps were downloaded from the Ensembl's BioMart data mining tool (http:// www.ensembl.org/multi/martview) and Genoscope database (http://www.genoscope.cns.fr/externe/English/Projets/ Projet_C/data/synteny/TN_HS_SYNT) [30, 31] . The exact locations for human, chimpanzee, Rhesus monkey, bushbaby, mouse lemur, dog, rat, mouse, opossum, platypus, X. tropicalis, O. latipes, D. rerio, T. rubripes, and T. nigroviridis (co)-orthologs were also verified by BLAT searches using the UCSC Genome Bioinformatics webserver (http://genome.ucsc.edu/cgi-bin/hgBlat) [32] . We inferred that a pair of duplicates in teleosts would be whole genome duplication (WGD)-derived co-orthologs if they were located on human-T. nigroviridis or human-D. rerio syntenic chromosomal regions. By contrast, CEACAM found on neighboring loci on the same chromosome were determined to have been derived from tandem duplications. Therefore, the presence of an ancestor for a select group of CEACAMs in the most recent common ancestor (MRCA) of a select lineage was deduced from analyses combining BLAST results and syntenic mapping. However, we cannot exclude the possibility, albeit a low probability, that some teleost homologs found on duplicated syntenic chromosomal regions were not WGD-derived coorthologs.