Comparative genome maps of the pangolin, hedgehog, sloth, anteater and human revealed by cross-species chromosome painting: further insight into the ancestral karyotype and genome evolution of eutherian mammals

Abstract

To better understand the evolution of genome organization of eutherian mammals, comparative maps based on chromosome painting have been constructed between human and representative species of three eutherian orders: Xenarthra, Pholidota, and Eulipotyphla, as well as between representative species of the Carnivora and Pholidota. These maps demonstrate the conservation of such syntenic segment associations as HSA3/21, 4/8, 7/16, 12/22, 14/15 and 16/19 in Eulipotyphla, Pholidota and Xenarthra and thus further consolidate the notion that they form part of the ancestral karyotype of the eutherian mammals. Our study has revealed many potential ancestral syntenic associations of human chromosomal segments that serve to link the families as well as orders within the major superordinial eutherian clades defined by molecular markers. The HSA2/8 and 7/10 associations could be the cytogenetic signatures that unite the Xenarthrans, while the HSA1/19p could be a putative signature that links the Afrotheria and Xenarthra. But caution is required in the interpretation of apparently shared syntenic associations as detailed analyses also show examples of apparent convergent evolution that differ in breakpoints and extent of the involved segments.

Zoo-FISH in the European mole <i>(Talpa europaea)</i> detects all ancestral Boreo-Eutherian human homologous chromosome associations

“…From the data obtained on the longeared hedgehog (Hemiechinus auritus) , the short-tailed shrew (Blarinella griselda) and the shrew-hedgehog (Neotetracus sinensis) , Ye et al (2006) conclude that syntenic segment association of human 4-20 homologues represents a lineage-specific chromosome signature for Eulipotyphla. This association, however, was not found in the mole (this study), but in the Javan pangolin ( Manis javanica , Pholidota; Yang et al, 2006). We consider the association 4-5 as a reliable Eulipotyphla signature since it is present in all species studied so far with the exception of the highly rearranged karyotype of S. araneus .…”

“…Since this report was accepted for publication, comparative chromosome maps between human and three additional Eulipotyphla were published (Yang et al, 2006;Ye et al, 2006). From the data obtained on the longeared hedgehog (Hemiechinus auritus) , the short-tailed shrew (Blarinella griselda) and the shrew-hedgehog (Neotetracus sinensis) , Ye et al (2006) conclude that syntenic segment association of human 4-20 homologues represents a lineage-specific chromosome signature for Eulipotyphla.…”

Construction, characterization and FISH mapping of a bacterial artificial chromosome library of Chinese pangolin <i>(Manis pentadactyla)</i>

“…A recent chromosome painting study between humans and the Javan pangolin has suggested several shared syntenic segment associations between Pholidota and Eulipotyphla, and between Pholidota and Carnivora (Yang et al, 2006). This has further complicated the interpretation of the phylogenetic position of Pholidota within supraorder Laurasiatheria.…”

Summary of Laurasiatheria (Mammalia) Phylogeny

“…Early karyotype studies of Laurasiatheria have suggested there are significant differences in chromosome number, morphology and banding pattern among the six orders (Ao et al, 2007;Frönicke et al, 1997;Kulemzina et al, 2009;Nie et al, 2011;SoteroCaio et al, 2011;Trifonov et al, 2008;Yang & Graphodatsky, 2004;Yang et al, 2006;Ye et al, 2006). Kulemzina et al (2010) investigated the phylogenetic relationships among Laurasiatheria orders by comparing their karyotypes with human karyotype, and proposed the Laurasiatheria phylogeny as (Eulipotyphla, (Cetartiodactyla, ((Perissodactyla, Chiroptera), (Carnivora, Pholidota)))) ( Figure 1A, Table 1).…”