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Abstract

In this paper, we present a radiation hybrid framework map of BTA13 composed of nine microsatellite loci, six genes and one EST. The map has been developed using a recently constructed 12'000 rad bovine-hamster whole-genome radiation hybrid panel. Moreover, we present a comprehensive map of BTA13 comprising 72 loci, of which 45 are microsatellites, 20 are genes and seven are ESTs. The map has an estimated length of 2694.7 cR_12'000. The proposed order is in general agreement with published maps of BTA13. Our results only partially support previously published information of five blocks of conserved gene order between cattle and man. We found no evidence for the existence of an HSA20 homologous segment of coding DNA on BTA13 located centromeric of a confirmed HSA10 homologous region. The present map increases the marker density and the marker resolution on BTA13 and enables further insight into the evolutionary development of the chromosome as compared to man.

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Genetic relationships between Swiss sheep breeds were estimated on the basis of microsatellite analysis. In addition to the Swiss breeds wild-type Mou¯on was included in this investigation. Polymerase chain reaction ampli®cations of 31 ovine, bovine and caprine microsatellites were performed in a total of 307 animals representing eight populations. The average heterozygosity within each population was high in the domestic breeds (0.60±0.71) and lower in Mou¯on 0.45. The average coef®cient of gene differentiation G ST over all loci was 0.17, i.e. a small part of the variability at the 31 microsatellite loci analysed must be ascribed to between-breed variability. Genetic distances between breeds were obtained, which were used to construct a phylogenetic tree. Microsatellites developed from closely related species of cattle and goat are useful for estimating genetic relationships among sheep breeds. ZusammenfassungGenetische Verwandtschaft bei Schweizer Schafrassen aufgrund der Analyse von Mikrosatelliten Die genetische Diversita Èt zwischen den Schweizer Schafrassen wurde anhand der Analyse von 31 ovinen, bovinen und caprinen Mikrosatelliten gescha Ètzt. DNA von 307 zufa Èllig ausgewa Èhlten Tieren wurde untersucht. Diese Tiere geho È ren den sieben Rassen Braunko È p®ges Fleischschaf, Schwarzbraunes Bergschaf, Schwarznasen-Schaf, Weisses Alpenschaf, Engadiner Schaf, Spiegelschaf und Walliser Landschaf an. Zusa Ètzlich wurde der Wildtyp des Hausschafes, der Muf¯on in die Untersuchung ein Veinbezogen bezogen. Der mittlere Heterozygotiegrad innerhalb der Rassen war fu È r die Hausschafe hoch (0.60±0.71), und beim Muf¯on lag dieser Wert etwas tiefer (0.45). Nur ein kleiner Teil der Gesamtvariation der genetischen Diversita Èt (G ST 0.17) konnte fu È r die Unterschiede zwischen den Rassen verantwortlich gemacht werden. Die gescha Ètzten genetischen Distanzen zwischen den Rassen wurden fu È r die Erstellung von phylogenetischen Ba Èumen verwendet. Die Untersuchung hat gezeigt, dass die ovinen, bovinen und caprinen Mikrosatelliten sich gleich gut fu È r die Analyse der genetischen Diversita Èt bei Schafen eignen.

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