Simple repetitive sequences are associated with differentiation of the sex chromosomes in the guppy fish |
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Authors: | Indrajit Nanda Wolfgang Feichtinger Michael Schmid Johannes H Schröder Hans Zischler Jörg T Epplen |
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Institution: | (1) Institut für Humangenetik der Universität, D-8700 Würzburg, Federal Republic of Germany;(2) Institut für Strahlenbiologie, Gesellschaft für Strahlen- und Umweltforschung München, D-8042 Neuherberg, Federal Republic of Germany;(3) Max-Planck-Institut für Psychiatrie, D-8033 Martinsried, Federal Republic of Germany |
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Abstract: | Summary Hybridization of restriction enzymedigested genomic guppy (Poecilia reticulata, Poeciliidae) DNA with the oligonucleotide probe (GACA)4 revealed a male-specific simple tandem repeat locus, which defines the Y chromosome in outbred populations. The related (GATA)4 probe identifies certain males with the red color phenotype. In contrast only in two out of eight laboratory guppy strains was the typical (GACA)4 band observed. By specific staining of the constitutive heterochromatin one pair of chromosomes could also be identified as the sex chromosomes, confirming the XX/XY mechanism of sex determination. All males exhibit Y chromosomes with a large region of telomeric heterochromatin. Hybridization in situ with nonradioactively labeled oligonucleotide probes localized the (GACA)n repeats to this heterochromatic portion. Together these results may be regarded as a recent paradigm for the differentiation of heteromorphic sex chromosomes from a pair of autosomes during the course of evolution. According to the fish model system, this may have happened in several independent consecutive steps. |
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Keywords: | Chromosomal sex determination Heterochromatin Junk gif" alt="ldquo" align="MIDDLE" BORDER="0">Junk DNA" target="_blank">gif" alt="rdquo" align="MIDDLE" BORDER="0"> DNA DNA fingerprinting Oligonucleotide hydridization in situ |
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