B chromosomes: the troubles of integration.
Starting with a spontaneous B-A centric fusion found in a natural population of the grasshopper Eyprepocnemis plorans, we have obtained different strains carrying the rearrangement in various conditions and doses. Using this material, we have analyzed the meiotic behavior of the translocated chromosome in living cultured spermatocytes, simulating the successive steps of a hypothetical process of integration of a B chromosome into the standard genome via B-A centric fusion. Remarkably, the behavior of fusion heterozygotes, the initial step of the integration process, is much more regular than that of any other configuration, including homozygotes. The reasons for the failure of B chromosome integration into the normal complement by translocation are discussed.
Departamento de Genética, Universidad Complutense, Madrid, Spain.
N
N
Granado
E
E
Rebollo
F J
FJ
Sánchez
P
P
Arana
D000818:Animals; D020090:Chromosome Segregation / Q000235:genetics; D002875:Chromosomes / Q000235:genetics*; D006110:Grasshoppers / Q000166:cytology / Q000235:genetics; D006579:Heterozygote; D006720:Homozygote; D008297:Male; D008540:Meiosis / Q000235:genetics; D014178:Translocation, Genetic / Q000235:genetics; D014960:X Chromosome / Q000235:genetics