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Digit ratio (2Dratio4D) differences between 20 strains of inbred mice
Reginia H Y Yan1, Mark Bunning, Douglas Wahlsten
1Department of Psychology, University of Alberta, Edmonton, Alberta, Canada.
Plos One
|June 5, 2009
Summary
The second to fourth digit ratio (2D:4D ratio) does not differ between male and female mice and does not correlate with behavior. This challenges its use as a universal indicator of prenatal testosterone exposure in mice.
Area of Science:
- Developmental biology
- Behavioral endocrinology
- Comparative anatomy
Background:
- The second to fourth digit ratio (2D:4D ratio) is sexually differentiated in many species, often linked to prenatal androgen exposure.
- In humans, lower 2D:4D ratios typically indicate higher prenatal testosterone and are associated with masculinized traits.
- Research in laboratory mice has yielded conflicting results regarding 2D:4D ratios and sex differences or masculinization.
Purpose of the Study:
- To investigate sex differences and inter-strain variations in forelimb and hindlimb 2D:4D ratios across 20 inbred mouse strains.
- To determine if 2D:4D ratios correlate with behavioral traits indicative of masculinization in mice.
- To evaluate the utility of the 2D:4D ratio as a reliable marker for prenatal androgen exposure in mice.
Main Methods:
- Measurement of forelimb and hindlimb 2D:4D ratios in 20 inbred mouse strains.
- Statistical analysis to detect sex differences and inter-strain variations.
- Correlation analysis between 2D:4D ratios and established mouse behavioral traits.
Main Results:
- No significant sexual dimorphism was observed in the 2D:4D ratios of the studied mouse strains.
- Large variations in 2D:4D ratios were found among different inbred mouse strains.
- Digit ratios did not show a significant correlation with the examined behavioral traits.
Conclusions:
- The 2D:4D ratio in mice does not appear to be a sexually dimorphic trait.
- The findings question the broad applicability of the 2D:4D ratio as an indicator of prenatal androgen exposure in laboratory mice.
- Inbred mouse models offer a valuable platform for exploring the genetic and gene-environment interactions influencing digit ratio development.
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