Bat Accelerated Regions Identify a Bat Forelimb Specific Enhancer in the HoxD Locus

Area of Science:

• Evolutionary biology
• Developmental biology
• Genomics

Background:

• The molecular mechanisms driving bat wing development are largely unknown.
• Changes in gene expression during limb development, potentially regulated by enhancers, are hypothesized to play a role.

Purpose of the Study:

• To identify rapidly evolved regulatory elements in bat ancestors using comparative genomics.
• To investigate the functional role of these elements in limb development and bat wing evolution.

Main Methods:

• Comparative genomics to identify bat accelerated regions (BARs).
• ChIP-sequencing (ChIP-seq) to identify active regulatory regions in developing mouse limbs.
• Mouse enhancer assays to test the function of identified BARs.
• Gene expression analysis of Hox genes in developing bat limbs.

Main Results:

• Identified 166 BARs overlapping active regulatory marks in mouse limb development.
• Demonstrated that five Myotis lucifugus BARs function as enhancers in the developing mouse limb.
• Observed differential enhancer activity between bat and mouse orthologous BARs, notably BAR116 near the HoxD cluster.
• Found a correlation between BAR116 activity and Hox gene expression patterns in developing bat limbs.

Conclusions:

• Novel regulatory regions (BARs) have been identified that likely contribute to bat wing evolution.
• Specific BARs, like BAR116, may regulate key developmental genes such as those in the HoxD cluster, influencing limb morphology.
• These findings provide insights into the genetic basis of unique bat adaptations.