Altered Circadian Period of Locomotor Activity in Carbonic Anhydrase II-Deficient Mice

This study finds lengthened circadian period in a congenic strain of mice homozygous for a null mutation in carbonic anhydrase isoenzyme-II gene on proximal Chromosome 3. Carbonic anhydrase II has the highest turnover rate of any constitutive enzyme. It catalyzes the reversible hydration of carbon dioxide to control intercellular acid/base balance. A strain of congenic mice has a carbonic anhydrase II null mutation within a DBA/2J inbred strain insert on a C57BL/6J inbred strain background. The locomotor activity levels and period of circadian rhythms were examined in the homozygous null mutants and their progenitors, mice heterozygous for the region around the carbonic anhydrase gene. The heterozygous mice siblings and the wild-type siblings served as the controls. During behavioral studies, male and female offspring and parents were housed singly in constant darkness. Locomotor activity was monitored using an infrared photobeam array. Mice homozygous for the carbonic anhydrase null mutation had a longer...