Influence of the bn gene on mitosis of immature red blood cells in turkeys.
The binucleated and large mononucleated red blood cells found in the blood of bnbn mutant turkeys result from nondisjunction of chromosomes in bone marrow polychromatic erythrocytes. The major ultrastructural abnormality that is observed in these mutant cells is malpositioning of the centrioles in the cell. This involves failure to assume a normal pole-to-pole position in the center of the cell, and, often, centrioles are seen close together near the cell membrane. In addition to the abnormalities in centrioles, incomplete spindles are formed with large masses of chromatin unattached to microtubules. Cytokinesis is blocked in many instances because large amounts of chromatin remain at the region of the metaphase plate. None of the aforementioned abnormalities were seen in bone marrow cells from genetically normal turkeys. The results of this study suggest that malorientation of the centrioles has adverse effects on chromosome movement in animal cells. The concept that the spatial orientation of the centrioles is fundamental in achieving normal separation of chromosomes during anaphase movement is supported by our work. Finally, the close ultrastructural parallels with the human blood disease congenital dyserythropoietic anemia type I are discussed.
D000818:Animals; D001854:Bone Marrow Cells; D002467:Cell Nucleus / Q000648:ultrastructure; D004912:Erythrocytes / Q000166:cytology*; D008938:Mitosis; D009154:Mutation; D014422:Turkeys / Q000235:genetics*