[Effects of ob genotype on early development in mice].

Objective: To study the effects and the extent of dominance of ob gene on early development in mice.

Methods: ob genotypes, wild type (+/+), hybrid type (ob/+) and mutant type (ob/ob), were detected by polymerase chain reaction and restrict endonuclease technique. Body weight of mice was recorded daily for the first seventh weeks of life. Their wet weight of white adipose tissue (WAT) and brown adipose tissue (BAT) was compared at the 7th, 14th and 24th days after birth.

Results: Body weight of ob/ob mice increased rapidly two weeks after birth and reached two times of that of +/+ and ob/+ mice seven weeks after birth. WAT of ob/ob mice was significantly higher than that of +/+ and ob/+ mice 24 days after birth. Effect of ob genotype on BAT was earlier than that on WAT. Body weight and WAT of ob/+ mice ranged between those of +/+ and ob/ob mice. Dominance index, reflecting the effect of ob gene on body weight, ranged from 1.0 - 0.5 within the first two weeks after birth, appearing co-dominance. And, dominance index approximated to 0.0 six weeks after birth, appearing almost complete recession.

Conclusion: Effect of ob gene on body weight and WAT initiated two weeks after birth and increased with age, developing gradually from co-dominance to recession in their early life.