NORMAL DEVELOPMENT, GROWTH AND REPRODUCTION IN CELLULAR RETINOIC ACID-BINDING PROTEIN-I (CRABPI) NULL MUTANT MICE

We have generated mouse null mutants for the cellular retinoic acid (R A) binding protein type I (CRABPI), a protein whose spatio-temporal ex pression pattern coincides with the target tissues for RA action. Inac tivation of the CRABPI gene was accomplished via homologous recombinat ion in embryonic stem cells. Cells carrying the correctly targeted gen e were injected into blastocysts and the resulting chimaeras yielded o ff spring heterozygous for the knockout mutation. Subsequent breeding programs resulted in normal litter sizes containing viable and fertile CRABPI deficient mice. Homozygous mice carrying the knockout mutation were studied in detail to detect possible organ and skeletal anomalie s and/or abnormalities of the hematopoietic system. No overt phenotype was evident indicating that a deficiency for CRABPI does not seem to interfere with normal development, growth and reproduction.