Chromosome Research

, Volume 9, Issue 8, pp 659–672

Meiotic chromosomes and stages of sex chromosome evolution in fish: zebrafish, platyfish and guppy

  • Walther Traut
  • Heinz Winking
Article

Abstract

We describe SC complements and results from comparative genomic hybridization (CGH) on mitotic and meiotic chromosomes of the zebrafish Danio rerio, the platyfish Xiphophorus maculatus and the guppy Poecilia reticulata. The three fish species represent basic steps of sex chromosome differentiation: (1) the zebrafish with an all-autosome karyotype; (2) the platyfish with genetically defined sex chromosomes but no differentiation between X and Y visible in the SC or with CGH in meiotic and mitotic chromosomes; (3) the guppy with genetically and cytogenetically differentiated sex chromosomes. The acrocentric Y chromosomes of the guppy consists of a proximal homologous and a distal differential segment. The proximal segment pairs in early pachytene with the respective X chromosome segment. The differential segment is unpaired in early pachytene but synapses later in an ‘adjustment’ or ‘equalization’ process. The segment includes a postulated sex determining region and a conspicuous variable heterochromatic region whose structure depends on the particular Y chromosome line. CGH differentiates a large block of predominantly male-specific repetitive DNA and a block of common repetitive DNA in that region.

comparative genomic hybridization fish cytogenetics sex chromosomes sex determination synaptonemal complex 

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Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Walther Traut
    • 1
  • Heinz Winking
    • 1
  1. 1.Institut für BiologieMedizinische Universität zu LübeckLübeckGermany

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