Mound-cell movement and morphogenesis in Dictyostelium.

Area of Science:

• Cell biology
• Developmental biology
• Microscopy

Background:

• Cell locomotion is crucial for multicellular development.
• Dictyostelium discoideum forms a three-dimensional (3-D) mound as an early developmental structure.
• Understanding cell movement within these mounds is key to deciphering developmental pathways.

Purpose of the Study:

• To investigate the mechanisms of cell locomotion within a 3-D cell mass.
• To analyze individual cell movements in Dictyostelium mounds using two distinct motile behaviors.
• To correlate cell motion patterns with developmental outcomes like fruiting body formation and slug migration.

Main Methods:

• Systematic 3-D analysis of individual cell movements.
• Time-lapse deconvolution microscopy of Dictyostelium mound strains (AX-2 and KAX-3).
• Observation of cell trajectories, optical-density wave patterns, and developmental morphogenesis under altered buffering conditions.

Main Results:

• AX-2 mounds showed slow, random/radial cell motion, while KAX-3 mounds exhibited faster, rotational motion.
• Optical-density waves correlated with motion but couldn't explain all behaviors.
• Altering buffering conditions changed both mound development (culmination vs. slug formation) and cell motion patterns.
• Chimeric mounds indicated a diffusible molecule induces rotation, but it didn't always lead to slug migration.

Conclusions:

• Cell motion within Dictyostelium mounds is linked to subsequent development but not rigidly determined.
• A diffusible factor likely induces rotational cell movement.
• Further research is needed to fully elucidate the complex interplay between cell motility and developmental fate in Dictyostelium.