A karyotype analysis by several staining techniques was carried out on triplicate samples of the shortnose sturgeon, Acipenser brevirostrum. The chromosome number was found to be 2n=372±6. A representative karyotype of 374 chromosomes was composed of 178 meta- submetacentrics, 196 telo- acrocentrics and microchromosomes. The signals of fluorescent in situ hybridization (FISH) with a Hind III satellite DNA probe were visible on 14 chromosomes. The signals obtained with the PstI satellite DNA probe appeared on 12 chromosomes. The FISH with 5S rDNA probe revealed fluorescent signals on 6 chromosomes. These last results, compared with 2 signals on species with about 120 chromosomes and 4 on species with 240, support the hypothesis that A. brevirostrum is a hexaploid species, probably of hybrid origin. Based on these results, we propose a model explaining speciation events occurred in sturgeons by hybridization, genome duplication and diploidization.
Evidence of hexaploid karyotype in shortnose sturgeon
FONTANA, Francesco;
2008
Abstract
A karyotype analysis by several staining techniques was carried out on triplicate samples of the shortnose sturgeon, Acipenser brevirostrum. The chromosome number was found to be 2n=372±6. A representative karyotype of 374 chromosomes was composed of 178 meta- submetacentrics, 196 telo- acrocentrics and microchromosomes. The signals of fluorescent in situ hybridization (FISH) with a Hind III satellite DNA probe were visible on 14 chromosomes. The signals obtained with the PstI satellite DNA probe appeared on 12 chromosomes. The FISH with 5S rDNA probe revealed fluorescent signals on 6 chromosomes. These last results, compared with 2 signals on species with about 120 chromosomes and 4 on species with 240, support the hypothesis that A. brevirostrum is a hexaploid species, probably of hybrid origin. Based on these results, we propose a model explaining speciation events occurred in sturgeons by hybridization, genome duplication and diploidization.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
