Spatial and temporal expression of a Polysphondylium spore-specific gene

Area of Science:

• Developmental Biology
• Cellular Slime Mold Morphogenesis
• Gene Regulation

Background:

• Cellular slime molds like Polysphondylium exhibit complex morphogenesis, transforming spherical cell masses into radially symmetric structures.
• Previous studies tracked morphogenesis using prestalk cell markers.

Purpose of the Study:

• To isolate and characterize a spore coat gene (sp-45) with an expression pattern complementary to prestalk cells.
• To elucidate the molecular mechanisms regulating sp-45 gene expression and prespore cell differentiation.

Main Methods:

• Cloning and promoter analysis of the sp-45 gene.
• Deletion analysis to identify regulatory elements (PRE, Gr box, TA box).
• Reporter gene assays and GFP fusion to study gene expression patterns.

Main Results:

• A positive regulatory element (PRE) was localized to a 106-bp fragment of the sp-45 promoter.
• The distal PRE, containing Gr and TA boxes, independently drives prespore cell-specific expression.
• Prespore gene expression is regulated by positive elements only; no negative regulatory elements were found.
• A sequence within the sp-45 coding region regulates graded gene expression.

Conclusions:

• Radial symmetry in Polysphondylium whorls is established by positional coordinates.
• Cell sorting plays a minimal role in this pattern formation process.
• The identified regulatory elements are crucial for prespore cell differentiation.