Expression of embryonic hemoglobin genes in mice heterozygous for. cap alpha. -thalassemia or. beta. -duplication traits and in mice heterozygous for both traits
Hemoglobins of mouse embryos at 11.5 through 16.5 days of gestation were separated by electrophoresis on cellulose acetate and quantitated by a scanning densitometer to study the effects of two radiation-induced mutations on the expression of embryonic hemoglobin genes in mice. Normal mice produce three kinds of embryonic hemoglobins. In heterozygous ..cap alpha..-thalassemic embryos, expression of EI (x/sub 2/y/sub 2/) and EII (..cap alpha../sub 2/y/sub 2/) is deficient because the x- and ..cap alpha..-globin genes of one of the allelic pairs of Hba on chromosome 11 was deleted or otherwise inactivated by X irradiation. Simultaneous inactivation of the x- and ..cap alpha..-globin genes indicates that these genes must be closely linked. Reduced x- and ..cap alpha..-chain synthesis results in an excess of y chains that associate as homotetramers. This unique y/sub 4/ hemoglobin also appears in ..beta..-duplication embryos where excess y chains are produced by the presence of three rather than two functional alleles of y- and ..beta..-globin genes. In double heterozygotes, which have a single functional allele of x- and ..cap alpha..-globin genes and three functional alleles of y- and ..beta..-globin genes, synthesis of ..cap alpha.. and non-..cap alpha.. chains is severely imbalanced and half of the total hemoglobin is y/sub 4/. Mouse y/sub 4/ has a high affinity for oxygen, P/sub 50/ of less than 10 mm Hg, but it lacks cooperativity so is inefficient for oxygen transport. The death of double heterozygotes in late fetal or neonatal life may be in large part to oxygen deprivation to the tissues.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5440350
- Journal Information:
- Dev. Biol.; (United States), Vol. 85
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HEMOGLOBIN
BIOSYNTHESIS
ELECTROPHORESIS
GENETIC RADIATION EFFECTS
MUTATIONS
RADIOINDUCTION
INACTIVATION
MICE
THALASSEMIA
X RADIATION
ANEMIAS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CARBOXYLIC ACIDS
DISEASES
ELECTROMAGNETIC RADIATION
GENETIC EFFECTS
GLOBIN
HEMIC DISEASES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IONIZING RADIATIONS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PORPHYRINS
PROTEINS
RADIATION EFFECTS
RADIATIONS
RODENTS
SYMPTOMS
SYNTHESIS
VERTEBRATES
560152* - Radiation Effects on Animals- Animals