the chicken as a model to study microchromosomes in birds a review鸡作为模型来研究鸟类microchromosomes审查.pdf

Review The chicken as a model to study microchromosomes in birds: a review Valérie Fillon Laboratoire de génétique cellulaire, Institut national de la recherche agronomique, BP27, 31326 Castanet-Tolosan cedex, France (Received 17 December 1997; accepted 22 April 1998) Abstract - The typical avian karyotype is composed of a few macrochromosomes and around 60 indistinguishable small microchromosomes. Due to its economic importance, the chicken is the avian species for which cytogenetic and genetic maps are the most developed. Based on these genome studies, it has been shown that the chicken microchromosomes are carriers of dense genetic information. Indeed, they probably bear at least 50 % of the genes and exhibit high recombination rates. Because of the of the size of the chicken presence microchromosomes, genetic genome seems higher than first estimated and could reach more than 4 000 cM for 1 200 Mb. Thus, it is worth developing the microchromosome map. From an evolutionary point of view, comparative mapping data raise many questions about the origin of microchromosomes. They could be ancestral chromosomes, from which large chromosomes formed by fusions, or conversely they could be the result of the splitting of macrochromosomes. copy; Inra/Elsevier, Paris microchromosome / chicken / genomic map / recombination rate Résumé - La Poule comme modèle d’étude des microchromosomes d’oiseaux : une revue. Le caryotype aviaire typique est constitué de quelques macrochromosomes et d’environ soixante microchromosomes punctiformes et indiscernables les uns des autres. Du fait de son importance économique, la Poule est l’espèce d’oiseaux dont les cartes génétique et cytogénétique sont les plus avancées. Ces études ont permis de montrer que les microchromosomes contiennent une infor