Cloned mice have an obese phenotype not transmitted to their offspring

Area of Science:

• Reproductive biology and developmental science.
• Animal cloning and genetic modification.

Background:

• Mammalian cloning from somatic cells is advancing, with potential clinical and therapeutic uses.
• Assessing long-term effects on cloned offspring is vital for technique application.
• Existing cloning methods may not yield phenotypically identical animals.

Purpose of the Study:

• To investigate the long-term effects of somatic cell cloning on mouse offspring.
• To determine if cloned mice exhibit phenotypic abnormalities, specifically related to body composition and weight.
• To assess the heritability of any observed phenotypes in subsequent generations.

Main Methods:

• Utilized a mouse model for its short generation time and lifespan.
• Performed somatic cell nuclear transfer to create cloned mice.
• Analyzed body weight, body composition (fat content), and general health of cloned mice.
• Conducted breeding studies with cloned mice to evaluate offspring phenotypes.

Main Results:

• Cloned B6C3F1 female mice exhibited increased body weight, primarily due to a significant increase in body fat.
• These cloned mice displayed characteristics consistent with obesity.
• The obese phenotype observed in the cloned mice was not transmitted to their offspring.

Conclusions:

• Somatic cell cloning in mice can lead to an obese phenotype characterized by increased body fat.
• The observed obesity in cloned mice is likely a consequence of the cloning process itself.
• The abnormal phenotype is not heritable, suggesting epigenetic or developmental reprogramming issues rather than stable genetic alterations.