Nondisjunction rates and abnormal embryonic development in a mouse cross between heterozygotes carrying a (7, 18) robertsonian translocation chromosome.
Mice bearing Robertsonian translocation chromosomes frequently produce aneuploid gametes. They are therefore excellent tools for studying nondisjunction in mammals. Genotypic analysis of embryos from a mouse cross between two different strains of mice carrying a (7,18) Robertsonian chromosome enabled us to measure the rate of nondisjunction for chromosomes 7 and 18. Embryos (429) were harvested from 76 litters of mice and the parental origin of each chromosome 7 and 18 determined. Genotyping these embryos has allowed us to conclude the following: (1) there were 96 embryos in which at least one nondisjunction event had taken place; (2) the rate of maternal nondisjunction was greater than paternal nondisjunction for teh chromosomes sampled in these mice; (3) a bias against chromosome 7 and 18 nullisomic gametes was observed, reflected in a smaller than expected number of uniparental disomic embryos; (4) nondisjunction events did not seem to occur at random throughout the 76 mouse litters, but were clustered into fewer than would be expected cy chance; and (5) a deficiency of paternal chromosome 18 uniparental disomic embryos was observed along with a higher than normal rate of developmental retardation at 8.5 days post coitum, raising the possibility that this chromosome has at least one imprinted gene.
Oakey
R J
RJ
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Matteson
P G
PG
Litwin
S
S
Tilghman
S M
SM
Nussbaum
R L
RL
D000782:Aneuploidy; D000818:Animals; D016009:Chi-Square Distribution; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005260:Female; D006580:Genetic Carrier Screening; D005838:Genotype; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000235:genetics; D008815:Mice, Inbred Strains; D009006:Monosomy; D009630:Nondisjunction, Genetic; D011336:Probability; D014178:Translocation, Genetic; D014314:Trisomy