Claim · model-written summary
One B chromosome caused little or no chromatin loss.
Zea maysNot reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingValueQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no or little loss occurs in spores with one B”
t0“MAIZE”
Title
ON THE MECHANISM OF CHROMATIN LOSS INDUCED BY THE B CHROMOSOME OF MAIZE
M M Rhoades; Ellen Dempsey Genetics 1972. doi:10.1093/genetics/71.1.73
Other claims from this paper (17)
- Intervention effect Knobbed regions were frequently eliminated at second microspore division with at least two B chromosomes.
- Intervention effect More than two B chromosomes did not increase loss rate.
- Intervention effect B chromosomes from an unrelated strain induced loss as effectively as those from the original high-loss stock.
- Observation B-induced chromatin loss was restricted to knobbed A chromosomes at second microspore division.
- Observation Knobbed chromosomes 3, 5 and 9 each interacted with B chromosomes to cause loss.
- Observation Large-knob chromosomes broke more often than small-knob chromosomes.
- Observation Knobless chromosomes showed negligible loss.
- Association Modifying genes markedly affected chromatin-loss rate.
- Observation Two knobbed heterologous chromosomes had simultaneous loss more often than expected from independent events.
- Observation Joint loss occurred in competent cells.
- Observation B and deficient chromosomes assorted independently at second microspore anaphase.
- Observation Crosses recovered diverse deficient chromosomes, indicating bridge breakage was not confined to the centric region.
- Observation B-chromosome nondisjunction occurred during second microspore mitosis.
- Observation Knobbed chromatin was eliminated during second microspore mitosis.
- Mechanism Faulty heterochromatin replication was proposed to explain nondisjunction and breakage.
- Mechanism Position of nonreplicating segments was proposed to determine nondisjunction versus breakage.
- Mechanism The authors propose that B chromosomes act as parasitic elements controlling knob replication and sperm competition.