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Cited by 153Chromosomal and Genetic VariationsGenome Rearrangement AlgorithmsGenetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities

Microchromosomes are building blocks of bird, reptile, and mammal chromosomes

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Waters, Paul D., Patel, Hardip R., Ruiz-Herrera, Aurora, Álvarez-González, Lucía, Lister, Nicholas C., Simakov, Oleg, Ezaz, Tariq, Kaur, Parwinder +4 more·2021·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.2112494118PMC PMC8609325

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Abstract

Significance: Genomes of birds and reptiles, but not mammals, consist of a few large chromosomes and many tiny microchromosomes. Microchromosomes are gene-rich and highly conserved among birds and reptiles and share homology with one or more of the tiny chromosomes of an invertebrate that diverged from the vertebrate lineage 684 Ma. Microchromosomes interact strongly and crowd together at the center of cells, suggesting functional coherence. Many microchromosomes have been lost independently in turtles, snakes, and lizards as they have fused with each other or with larger chromosomes. In mammals they have completely disappeared, yet some chromosomes of the basal platypus line up with several microchromosomes, suggesting that they are the building blocks of the atypically variable chromosomes of mammals.

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  • These patterns of conservation hold largely for smaller chromosomes across vertebrates, including mammals.

    “These patterns of conservation hold largely for smaller chromosomes across vertebrates, including mammals (65, 67, 100)”

    From Topological Approaches in Animal Comparative Genomics (2026) · cites this paper as [100]

    The Abstract describes microchromosomes as highly conserved among birds and reptiles. But the Results (‘The Fate of Microchromosomes in Mammals’) find no intact microchromosomes in the human or koala genomes and no enrichment of ancestral microchromosomes in small platypus chromosomes. The extension of this conservation pattern to smaller mammalian chromosomes is therefore not supported. (LLM, conf=0.88)

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Authors
Waters, P. D., Patel, H. R., Ruiz-Herrera, A., Álvarez-González, L., Lister, N. C., Simakov, O., Ezaz, T., Kaur, P., Frere, C., Grützner, F., Georges, A., & Graves, J. A. M.
Affiliations
  • UNSW Sydney (AU)
  • Australian National University (AU)
  • Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Spain;
  • Universitat Autònoma de Barcelona (ES)
  • University of Vienna (AT)
  • University of Canberra (AU)
  • The University of Western Australia (AU)
  • Global Change Ecology Research Group, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia;
  • The University of Adelaide (AU)
Corresponding author
Graves, Jennifer A. Marshall
ORCID
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2021-11
Volume
118
Issue
45
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.2112494118
PMC
PMC8609325
OpenAlex
W3210280275
Cited by
153
References
1
Citations by year
2026: 21 · 2025: 35 · 2024: 31 · 2023: 41 · 2022: 23 · 2021: 2
FWCI
16.33
Type
journal article
Language
en
Open access
Licence
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • ANU Open Research (Australian National University) (submittedVersion, cc-by)
  • Dipòsit Digital de Documents de la UAB (Universitat Autònoma de Barcelona) (submittedVersion, cc-by)
  • Adelaide Research & Scholarship (AR&S) (University of Adelaide) (submittedVersion, cc-by)
  • UWA Profiles and Research Repository (UWA) (submittedVersion, cc-by)
Funders
ARC | Centre of Excellence for Electromaterials Science, Australian Research Council (DP170101147, DP180100931, DP210103512, FT200100192)
Topics
  • Life Sciences › Agricultural and Biological Sciences › Plant Science › Chromosomal and Genetic Variations
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genome Rearrangement Algorithms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities
Keywords
microchromosomes, karyotype evolution, chromosome fusion, synteny, amphioxus, turtles, Squamata, monotremes, therian mammals, chromosome conformation, avian chromosomes
MeSH terms
Animals, Base Sequence, Biological Evolution, Genome, Conserved Sequence, Chromosomes, Mammalian, Chordata

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