Genealogies inferred for C. aureofulvus and C. napus (data not shown) did not have enough genetic polymorphisms to resolve transoceanic disjunction events.
In contrast, a meiosis I non-disjunction event will generate an ascus where two of the spores contain two GFP signals and two spores lack GFP altogether.
Binucleate cells with GFP signal in only one of the two nuclei were categorized as having experienced a meiosis I non-disjunction event (n = 100).
Briefly, these mice are the offspring of heterozygotes for the T(2 9 11H reciprocal translocation that have inherited the distal part of both homologous copies of Chr 2 from either the mother, MatDp(dist2), or the father, PatDp(dist2), due to a non-disjunction event.
We do not unambiguously know the origin of these males, but since they were invariably sterile they are likely XO male progeny resulting from meiotic non-disjunction events in the Roc1aG1/FM7 females.
We have used extensive molecular genotyping in mice to study non-disjunction events in mice with a Robertsonian chromosome.
Furthermore as women age, so the frequency of chromosomal abnormalities due to aneuploidy and non-disjunction events rises (Pellestor et al., 2003).
C. elegans males are formed either as a result from rare non-disjunction events during hermaphrodite gametogenesis, or as cross-progeny from hermaphrodite/male crosses.
Persistence of males in P. pacificus could be explained as a byproduct of the sex determination system, where males are generated by X chromosome non-disjunction events in hermaphrodite meiosis.
In C. elegans, the frequency of XX hermaphrodites and XO males in a population is mainly driven by (1) the rate of non-disjunction events of the X chromosome during gametogenesis in hermaphrodites and (2) the ability of males to produce cross-progeny.
The pictures here, made by Kenneth Graves as a young man in the Bay Area, show a world full of disjunction, of oddball events that seem to fall out of the sky and into his lap or, more appropriately, into his field of vision.
