Autosomal localization of the amelogenin gene in monotremes and marsupials: Implications for mammalian sex chromosome evolution

doi:10.1016/S0888-7543(05)80187-9

Genomics

Volume 14, Issue 3, November 1992, Pages 785-789

https://doi.org/10.1016/S0888-7543(05)80187-9 Get rights and content

We have determined by Southern blot analysis that DNA sequences homologous to the AMG gene probe are present in the genomes of both marsupial and monotreme mammals, although adult monotremes lack teeth. In situ hybridization and Southern analysis of cell hybrids demonstrate that AMG homologues are located on autosomes. In the Tammar Wallaby, AMG homologues are located on chromosomes 5q and 1q and in the Platypus, on chromosomes 1 and 2. The autosomal location of the AMG homologues provides additional support for the hypothesis that an autosomal region equivalent to the human Xp was translocated to the X chromosome in the Eutheria after the divergence of the marsupials 150 million years ago. The region containing the AMG gene is therefore likely to have been added 80–150 million years ago to a pseudoautosomal region shared by the ancestral eutherian X and Y chromosome; the X and Y alleles must have begun diverging after this date.

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Cited by (27)

The monotreme genome: A patchwork of reptile, mammal and unique features?
2003, Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology
The first specimen of platypus (Ornithorhynchus anatinus) that reached Britain in the late 18th century was regarded a scientific hoax. Over decades the anatomical characteristics of these unique mammals, such as egg laying and the existence of mammary glands, were hotly debated before they were accepted. Within the last 40 years, more and more details of monotreme physiology, histology, reproduction and genetics have been revealed. Some show similarities with birds or reptiles, some with therian mammals, but many are very specific to monotremes. The genome is no exception to monotreme uniqueness. An early opinion was that the karyotype, composed of a few large chromosomes and many small ones, resembled bird and reptile macro- and micro-chromosomes. However, the platypus genome also features characteristics that are not present in other mammals, such as a complex translocation system. The sex chromosome system is still not resolved. Nothing is known about dosage compensation and, unlike in therian mammals, there seems to be no genomic imprinting. In this article we will recount the mysteries of the monotreme genome and describe how we are using recently developed technology to identify chromosomes in mitosis, meiosis and sperm, to map genes to chromosomes, to unravel the sex chromosome system and the translocation chain and investigate X inactivation and genomic imprinting in monotremes.
Sequences homologous to the human x- and y-borne zinc finger protein genes (zfx/y) are autosomal in monotreme mammals
1993, Genomics
The human zinc finger protein genes (ZFX/Y) were identified as a result of a systematic search for the testis-determining factor gene on the human Y chromosome. Although they play no direct role in sex determination, they are of particular interest because they are highly conserved among mammals, birds, and amphibians and because, in eutherian mammals at least, they have active alleles on both the X and the Y chromosomes outside the pseudoautosomal region. We used in situ hybridization to localize the homologues of the zinc finger protein gene to chromosome 1 of the Australian echidna and to an equivalent position on chromosomes 1 and 2 of the platypus. The localization to platypus chromosome 1 was confirmed by Southern analysis of a Chinese hamster X platypus cell hybrid retaining most of platypus chromosome 1. This localization is consistent with the cytological homology of chromosome 1 between the two species. The zinc finger protein gene homologues were localized to regions of platypus chromosomes 1 and 2 that included a number of other genes situated near ZFX on the short arm of the human X chromosome. These results support the hypothesis that many of the genes located on the short arm of the human X were originally autosomal and have been translocated to the X chromosome since the eutherian-metatherian divergence.
Mapping human X-linked genes in the phalangerid marsupial Trichosurus vulpecula
1992, Genomics
We mapped 15 human X-chromosome markers in the common brush-tailed possum, Trichosurus vulpecula (Kerr), which represents the Australian marsupial family Phalangeridae. In situ hybridization was used to localize highly conserved human X-linked genes to chromosomes of T. vulpecula diploid lines. Ten genes located on the long arm of the human X (human Xq genes) all mapped to the possum X chromosome. However, all five genes located on the short arm of the human X (human Xp genes) mapped to autosomes. These findings confirm our previous work, which showed that the X chromosome in macropodid and dasyurid marsupials bears all the human Xq genes but none of the human Xp genes studied. This suggests that the marsupial X is highly conserved, but its gene content reflects that of only part of the eutherian X, a result consistent with our hypothesis that an autosomal region was added to the X early in eutherian divergence.
Sex identification of pigs using polymerase chain reaction amplification of the amelogenin gene
2008, Zygote
Molecular biology of the amelogenin gene
2017, Dental Enamel Formation to Destruction
A new PCR assay for reliable molecular sexing of endangered Tasmanian devils (Sarcophilus harrisii) from non-invasive genetic samples
2011, Conservation Genetics Resources

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¹: Present address: Beckman Institute, City of Hope Medical Center, Duarte, CA 91010-0269.

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Genomics

References (29)

Linkage of amelogenin (Amel) to the distal portion of the mouse X chromosome

Genomics

Statistical analysis of in situ hybridization data: Derivation and use of the z_max test

Genomics

Human and mouse amelogenin gene loci are on the sex chromosomes

Genomics

A human X-Y homologous region encodes “Amelogenin”

Genomics

The sex-determining region of the human Y chromosome encodes a finger protein

Cell

DNA sequence for cloned cDNA for murine amelogenin reveal the amino acid sequence for enamel-specific protein

Biochem. Biophys. Res. Commun.

The X chromosome of marsupials shares a highly conserved region with eutherians

Genomics

Genes on the short arm of human X chromosome are not shared with the marsupial X

Genomics

Noninactivation of a selectable human X-linked gene that complements a murine temperature-sensitive cell cycle defect

Am. J. Hum. Genet.

Steroid sulphatase is not detected on the chromosome of Australian marsupials

Cytogenet. Cell Genet.

Gene mapping in marsupials and monotremes. III. Assignment of four genes to the X chromosome of the Wallaroo and the Euro (Macropus robustus)

Cytogenet. Cell Genet.

Human developing enamel proteins exhibit a sex-linked dimorphism

Calcif. Tissue Int.

Homologous ribosomal protein genes on the human X and Y chromosomes: Escape from X inactivation and possible implications for Turner Syndrome

Cell

Marsupial gene mapping and the evolution of mammalian sex chromosome form and function

Cited by (27)

The monotreme genome: A patchwork of reptile, mammal and unique features?

Sequences homologous to the human x- and y-borne zinc finger protein genes (zfx/y) are autosomal in monotreme mammals

Mapping human X-linked genes in the phalangerid marsupial Trichosurus vulpecula

Sex identification of pigs using polymerase chain reaction amplification of the amelogenin gene

Molecular biology of the amelogenin gene

A new PCR assay for reliable molecular sexing of endangered Tasmanian devils (Sarcophilus harrisii) from non-invasive genetic samples

Short CommunicationAutosomal localization of the amelogenin gene in monotremes and marsupials: Implications for mammalian sex chromosome evolution

Genomics

Genomics

Genomics

Genomics

Cell

Biochem. Biophys. Res. Commun.

Genomics

Genomics

Noninactivation of a selectable human X-linked gene that complements a murine temperature-sensitive cell cycle defect

Am. J. Hum. Genet.

Steroid sulphatase is not detected on the chromosome of Australian marsupials

Cytogenet. Cell Genet.

Gene mapping in marsupials and monotremes. III. Assignment of four genes to the X chromosome of the Wallaroo and the Euro (Macropus robustus)

Cytogenet. Cell Genet.

Human developing enamel proteins exhibit a sex-linked dimorphism

Calcif. Tissue Int.

Homologous ribosomal protein genes on the human X and Y chromosomes: Escape from X inactivation and possible implications for Turner Syndrome

Cell

Marsupial gene mapping and the evolution of mammalian sex chromosome form and function

Short Communication
Autosomal localization of the amelogenin gene in monotremes and marsupials: Implications for mammalian sex chromosome evolution