Non-disjunction in an Œnothera interchange heterozygote

Non-disjunction of an unusual X chromosome.

Because of multiple abnormalities in her children, a young mother was investigated and shown to have a 47,XXX chromosome constitution. Additional C group chromosomes without visible centromeric constrictions were found in a number of cells from the peripheral blood, and using C and Q banding techniques these chromosomes were identified as X chromosomes. Analysis of the banding karyotypes of 300...

Androlethal Factors in Œnothera

The genetic behavior of ~Enothera biennis and O. syrticola (0. muricata L.) as uniform and constant species is now generally explained by the assumption of the presence of two gametic lethal factors. The reciprocal hybrids of these forms are unlike each other and the double reciprocal hybrids return to the grandparental types. I t is assumed that there are two kinds of gametes, but that one of ...

Non-disjunction of chromosome 18.

A sample of 100 trisomy 18 conceptuses analysed separately and together with a published sample of 61 conceptuses confirms that an error in maternal meiosis II (MII) is the most frequent cause of non-disjunction for chromosome 18. This is unlike all other human trisomies that have been studied, which show a higher frequency in maternal meiosis I (MI). Maternal MI trisomy 18 shows a low frequenc...

Non-disjunction of chromosome 13.

We performed a molecular study with 21 microsatellites on a sample of 82 trisomy 13 conceptuses, the largest number of cases studied to date. The parental origin was determined in every case and in 89% the extra chromosome 13 was of maternal origin with an almost equal number of maternal MI and MII errors. The latter finding is unique among human autosomal trisomies, where maternal MI (trisomie...

Primary Non-Disjunction in Drosophila Hydei