Acoel Single-Cell Transcriptomics: Cell Type Analysis of a Deep Branching Bilaterian

Area of Science:

• Developmental Biology
• Evolutionary Biology
• Genomics

Background:

• Bilaterian animals possess complex cell types and organ systems, unlike simpler prebilaterian ancestors.
• The Xenacoelomorpha, an early bilaterian phylum, exhibit a simplified anatomy and have diverged significantly from other bilaterian lineages.

Purpose of the Study:

• To identify and characterize the diverse cell types within the acoel Isodiametra pulchra.
• To investigate the molecular basis of cell type diversity in early-branching bilaterians.

Main Methods:

• Whole-body single-cell RNA sequencing (scRNA-seq) was performed on the acoel Isodiametra pulchra.
• Bioinformatic analyses were used to cluster cells and identify marker genes for distinct cell types.

Main Results:

• Ten major cell type categories were identified in Isodiametra pulchra, involved in metabolism, locomotion, behavior, defense, and development.
• While many cell types express conserved bilaterian marker genes, a significant number of clade-specific marker genes were discovered.
• These findings suggest the evolution of unique molecular mechanisms underlying cell type specification in acoels.

Conclusions:

• The study provides a comprehensive catalog of cell types in acoels, offering insights into bilaterian cell type evolution.
• The identification of clade-specific genes highlights the molecular innovations driving the diversification of cell types in early bilaterian lineages.
• This research deepens our understanding of the origins of the bilaterian body plan and its constituent cell types.