An arthropod cis-regulatory element functioning in sensory organ precursor development dates back to the Cambrian

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Genetics

Background:

• Functional conservation of cis-regulatory elements can occur without sequence similarity, particularly in invertebrates.
• The sensory organ precursor enhancer (SOPE) is a regulatory element crucial for lateral inhibition, a process essential for neural precursor selection.
• The SOPE was first identified in Drosophila and regulates genes of the achaete-scute family.

Purpose of the Study:

• To investigate the evolutionary history and conservation of the sensory organ precursor enhancer (SOPE) across different arthropod groups.
• To determine if the SOPE functions in neural precursor selection in species beyond Drosophila.

Main Methods:

• Manual comparison of consensus binding site sequences to identify SOPEs in asense-like genes across Crustacea, Myriapoda, Chelicerata, and Insecta.
• Functional analysis of SOPEs from Cupiennius salei (spider) and Tribolium castaneum (insect) in transgenic Drosophila.

Main Results:

• A conserved SOPE was identified in the UTR sequences of asense-like genes from all four major arthropod groups.
• The SOPEs from Cupiennius salei and Tribolium castaneum demonstrated functionality in transgenic Drosophila.
• The findings suggest the SOPE originated in the last common ancestor of Arthropoda, dating back to the Cambrian period (550 million years ago).

Conclusions:

• The SOPE is an ancient regulatory module with conserved function across diverse arthropods, originating over 550 million years ago.
• The lack of sequence similarity for the SOPE highlights the limitations of inter-specific sequence comparison for detecting ancient regulatory elements.
• This suggests that other ancient invertebrate regulatory modules may have evaded detection due to sequence divergence.