[Lactase and its gene regulation in BALB/c mice at different ages]

In order to clarify the trend of change in lactase and its gene regulation pattern, the authors determined the lactase activities and mRNA levels in BALB/c mice at different ages.

The lactase activities and mRNA levels of the 3-, 5-, 7-, 9- week old mice were determined by the modified method of Dahlqvist and in situ hybridization respectively.

The 3 wk old mice had the highest lactase activities, to the contrary, the 9 wk old mice had the lowest lactase activities. Meanwhile, the lactase mRNA levels displayed no diversities.

The mice had higher lactase activities before weaning, but significantly very low activities after weaning. These findings indicate that BALB/c mice have the same adult-type hypolactasia as human. No statistically significant difference in lactase mRNA levels between the 4 age-groups implies that lactase gene is regulated at the translational and/or post-translational levels, but not at the transcriptional level.