Chromosomal instability in Afrotheria : fragile sites, evolutionary breakpoints and phylogenetic inference from genome sequence assemblies

dc.contributor.authorRuiz-Herrera, Aurora
dc.contributor.authorRobinson, Terence J.
dc.identifier.citationRuiz-Herrera, A & Robinson, TJ 2007, 'Chromosomal instability in Afrotheria: fragile sites, evolutionary breakpoints and phylogenetic inference from genome sequence assemblies', BMC Evolutionary Biology, 7(1):199.en_ZA
dc.descriptionIncludes bibliography
dc.description.abstractBackground: Extant placental mammals are divided into four major clades (Laurasiatheria, Supraprimates, Xenarthra and Afrotheria). Given that Afrotheria is generally thought to root the eutherian tree in phylogenetic analysis of large nuclear gene data sets, the study of the organization of the genomes of afrotherian species provides new insights into the dynamics of mammalian chromosomal evolution. Here we test if there are chromosomal bands with a high tendency to break and reorganize in Afrotheria, and by analyzing the expression of aphidicolin-induced common fragile sites in three afrotherian species, whether these are coincidental with recognized evolutionary breakpoints. Results: We described 29 fragile sites in the aardvark (OAF) genome, 27 in the golden mole (CAS), and 35 in the elephant-shrew (EED) genome. We show that fragile sites are conserved among afrotherian species and these are correlated with evolutionary breakpoints when compared to the human (HSA) genome. In addition, by computationally scanning the newly released opossum (Monodelphis domestica) and chicken sequence assemblies for use as outgroups to Placentalia, we validate the HSA 3/21/5 chromosomal synteny as a rare genomic change that defines the monophyly of this ancient African clade of mammals. On the other hand, support for HSA 1/19p, which is also thought to underpin Afrotheria, is currently ambiguous. Conclusion: We provide evidence that (i) the evolutionary breakpoints that characterise human syntenies detected in the basal Afrotheria correspond at the chromosomal band level with fragile sites, (ii) that HSA 3p/21 was in the amniote ancestor (i.e., common to turtles, lepidosaurs, crocodilians, birds and mammals) and was subsequently disrupted in the lineage leading to marsupials. Its expansion to include HSA 5 in Afrotheria is unique and (iii) that its fragmentation to HSA 3p/21 + HSA 5/21 in elephant and manatee was due to a fission within HSA 21 that is probably shared by all Paenungulata.en_ZA
dc.format.extent15 p. : il., some col.
dc.publisherBioMed Centralen_ZA
dc.subjectExtant placental mammalsen_ZA
dc.subjectGenomes of Afrotherian speciesen_ZA
dc.subjectMammalian chromosomal evolutionen_ZA
dc.subjectChromosome bandingen_ZA
dc.titleChromosomal instability in Afrotheria : fragile sites, evolutionary breakpoints and phylogenetic inference from genome sequence assembliesen_ZA
dc.description.versionPeer Reviewed
dc.rights.holderRuiz-Herrera et al.; licensee BioMed Central Ltd.en_ZA

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