Microchromosomes are building blocks of bird, reptile, and mammal chromosomes
Waters, Paul D. (UNSW Sydney. School of Biotechnology and Biomolecular Science)
Patel, Hardip R. (Australian National University. The John Curtin School of Medical Research)
Ruiz-Herrera Moreno, Aurora (Universitat Autònoma de Barcelona. Institut de Biotecnologia i de Biomedicina "Vicent Villar Palasí")
Álvarez-González, Lucía (Universitat Autònoma de Barcelona. Departament de Biologia Cel·lular, de Fisiologia i d'Immunologia)
Lister, Nicholas C. (UNSW Sydney. School of Biotechnology and Biomolecular Science)
Simakov, Oleg (University of Vienna. Department of Neurosciences and Developmental Biology)
Ezaz, Tariq (University of Canberra. Institute for Applied Ecology)
Kaur, Parwinder (The University of Western Australia. UWA School of Agriculture and Environment)
Frere, Celine (University of the Sunshine Coast (Australia))
Grutzner, Frank (University of Adelaide. School of Biological Sciences (Australia))
Georges, Arthur (University of Canberra. Institute for Applied Ecology)
Marshall Graves, Jennifer A. (La Trobe University. School of Life Sciences (Australia))

Date:	2021
Abstract:	Microchromosomes, once considered unimportant shreds of the chicken genome, are gene-rich elements with a high GC content and few transposable elements. Their origin has been debated for decades. We used cytological and whole-genome sequence comparisons, and chromosome conformation capture, to trace their origin and fate in genomes of reptiles, birds, and mammals. We find that microchromosomes as well as macrochromosomes are highly conserved across birds and share synteny with single small chromosomes of the chordate amphioxus, attesting to their origin as elements of an ancient animal genome. Turtles and squamates (snakes and lizards) share different subsets of ancestral microchromosomes, having independently lost microchromosomes by fusion with other microchromosomes or macrochromosomes. Patterns of fusions were quite different in different lineages. Cytological observations show that microchromosomes in all lineages are spatially separated into a central compartment at interphase and during mitosis and meiosis. This reflects higher interaction between microchromosomes than with macrochromosomes, as observed by chromosome conformation capture, and suggests some functional coherence. In highly rearranged genomes fused microchromosomes retain most ancestral characteristics, but these may erode over evolutionary time; surprisingly, de novo microchromosomes have rapidly adopted high interaction. Some chromosomes of early-branching monotreme mammals align to several bird microchromosomes, suggesting multiple microchromosome fusions in a mammalian ancestor. Subsequently, multiple rearrangements fueled the extraordinary karyotypic diversity of therian mammals. Thus, microchromosomes, far from being aberrant genetic elements, represent fundamental building blocks of amniote chromosomes, and it is mammals, rather than reptiles and birds, that are atypical.
Grants:	Agencia Estatal de Investigación CGL2017-83802-P Agencia Estatal de Investigación PID2020-112557GB-I00 Ministerio de Economía y Competitividad PRE-2018-083257
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Vertebrate chromosome evolution ; Whole-genome alignment ; Chromosome conformation ; Microchromosome origin ; Amphioxus
Published in:	Proceedings of the National Academy of Sciences of the United States of America, Vol. 118, Issue 45 (November 2021) , art. e2112494118, ISSN 1091-6490

DOI: 10.1073/pnas.2112494118
PMID: 34725164

11 p, 1.4 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Health sciences and biosciences > Institut de Biotecnologia i de Biomedicina (IBB)
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