Crossing over in chicken oogenesis: cytological and chiasma-based genetic maps of the chicken lampbrush chromosome 1.
Chiasmata in diplotene bivalents are located at the points of physical exchange (crossing-over) between homologous chromosomes. We have studied chiasma distribution within chicken lampbrush chromosome 1 to estimate the crossing-over frequency between chromosome landmarks. The position of the centromere and chromosome region 1q3.3-1q3.6 on lampbrush chromosome 1 were determined by comparative physical mapping of the TTAGGG repeats in the chicken mitotic and lampbrush chromosomes. The comparison of the chiasma (=crossing over)-based genetic distances on chicken chromosome 1 with the genetic linkage map obtained in genetic experiments showed that current genetic distances estimated by the high-resolution genetic mapping of the East Lansing, Compton, and Wageningen chicken reference populations are 1.2-1.9 times longer than those based on chiasma counts. Conceivable reasons for this discrepancy are discussed.
Biological Institute, St. Petersburg State University, Stary Peterhof, St. Petersburg 198504, Russia. Alexander.Rodionov@pobox.spbu.ru
A V
AV
Rodionov
N A
NA
Lukina
S A
SA
Galkina
I
I
Solovei
S
S
Saccone
D000818:Animals; D002645:Chickens / Q000235:genetics*; D002874:Chromosome Mapping; D003434:Crossing Over, Genetic; D005260:Female; D008540:Meiosis / Q000235:genetics; D009866:Oogenesis / Q000235:genetics*