Salt affects structure, function and transcriptome in the giant cells of slime molds

Area of Science:

• Cell Biology
• Physiology
• Genomics

Background:

• Salt is vital for life but excess disrupts fluid balance in multicellular organisms.
• The response to salt stress in single-celled organisms remains less understood.
• Physarum polycephalum, a giant single-celled slime mold, offers a unique model for studying cellular salt responses.

Purpose of the Study:

• To investigate the phenotypic and transcriptomic effects of excessive sodium chloride on the giant cellular slime mold, Physarum polycephalum.
• To understand the molecular mechanisms underlying salt stress mitigation in a single-celled organism.

Main Methods:

• Exposure of Physarum polycephalum plasmodia to varying concentrations of sodium chloride.
• Morphological analysis of tubular network architecture and peristaltic contractions.
• Transcriptomic analysis to identify differentially expressed genes.

Main Results:

• Excess salt altered network vein diameter and peristaltic contraction frequency.
• Over 2000 genes were differentially expressed, with upregulation of ion transporters and stress pathways.
• Downregulation of genes involved in metabolic degradation was observed.

Conclusions:

• Physarum polycephalum employs ion homeostasis, cytoskeletal adjustments, and defense gene modulation to manage salt stress.
• The study provides insights into the evolution of salt stress responses from basal protists to animals and fungi.