Evidence of hexaploid karyotype in shortnose sturgeon.
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 metacentrics/submetacentrics and 196 telocentrics/acrocentrics and microchromosomes. The signals of fluorescent in situ hybridization (FISH) with a HindIII satellite DNA probe were visible on 14 chromosomes. The signals obtained with a PstI satellite DNA probe appeared on 12 chromosomes. The FISH with a 5S rDNA probe revealed fluorescent signals on 6 chromosomes. These last results, compared with 2 signals in species with about 120 chromosomes and 4 in 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 occurring in sturgeons by hybridization, genome duplication, and diploidization.
Fontana
Francesco
F
Dipartimento di Biologia ed Evoluzione, Universita di Ferrara, Via L. Borsari, 46, 44100 Ferrara, Italy. francesco.fontana@unife.it
Congiu
Leonardo
L
Mudrak
Vincent A
VA
Quattro
Joseph M
JM
Smith
Theodore I J
TI
Ware
Kent
K
Doroshov
Serge I
SI
D000818:Animals; D004275:DNA, Ribosomal / Q000235:genetics; D005399:Fishes / Q000235:genetics*; D020440:Gene Duplication; D016678:Genome; D007621:Karyotyping; D008938:Mitosis; D009693:Nucleic Acid Hybridization; D011123:Polyploidy
D004275:DNA, Ribosomal