Chromosome banding in Amphibia. XIX. Primitive ZW/ZZ sex chromosomes in Buergeria buergeri (Anura, Rhacophoridae)

Cytogenetics and Cell Genetics
M SchmidM Guttenbach

Abstract

The karyotype of the common bell-ring frog, Buergeria buergeri, is characterized by primitive ZW/ZZ (female/male) sex chromosomes. The only difference between the Z and W is the presence of a nucleolus organizer region (NOR) and its associated constitutive heterochromatin in the Z. This causes a sex-specific difference in the number of ribosomal RNA genes, with a male:female ratio of about 2:1. In the cell nuclei of the various tissues analyzed the NORs on both Z chromosomes are transcriptionally active. During meiosis in females, the ZW chromosomes form a characteristic lampbrush sex bivalent with a conspicuous absence of chiasmata along half of their long arms. No further morphological differences are present in these primitive sex chromosomes. The results indicate that there is no Z-chromosome inactivation mechanism operating in this amphibian. Experimental sex reversal of genetic (ZW) females to functional males was achieved by estrogen treatment of tadpoles. Mating of sex-reversed females with normal females yields the expected 25% lethal nucleoli-less WW embryos, which die at the tail-bud stage. The sex of the remaining viable embryos with one or two nucleoli determined after metamorphosis was in a female:male ratio of 1....Continue Reading

Citations

Oct 14, 2008·Chromosome Research : an International Journal on the Molecular, Supramolecular and Evolutionary Aspects of Chromosome Biology·Yoshinobu UnoYoichi Matsuda
Mar 2, 2012·Cytogenetic and Genome Research·A-M Dutrillaux, B Dutrillaux
Mar 21, 2013·Chromosome Research : an International Journal on the Molecular, Supramolecular and Evolutionary Aspects of Chromosome Biology·Daleen BadenhorstNicole Valenzuela
Nov 26, 2009·Chromosome Research : an International Journal on the Molecular, Supramolecular and Evolutionary Aspects of Chromosome Biology·John AbramyanPeter Koopman
Apr 1, 2004·Journal of Experimental Zoology. Part B, Molecular and Developmental Evolution·Masayuki SumidaTamotsu Fujii
May 1, 2021·Genes·Álvaro S RocoMónica Bullejos

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