A first glimpse at the transcriptome of Physarum polycephalum

Area of Science:

• Eukaryotic evolution
• Cell biology
• Genomics

Background:

• Physarum polycephalum is an acellular amoebozoan with a complex life cycle and rich cell biology.
• Over 2500 publications exist on P. polycephalum, covering its biochemistry, development, cytoskeleton, and motility.
• Genetic manipulation is now possible, enabling targeted functional analysis.

Purpose of the Study:

• To analyze a significant portion of transcribed genes in the plasmodial stage of P. polycephalum.
• To identify genes involved in signaling networks and environmental response.
• To investigate alternative splicing patterns and their evolutionary significance.

Main Methods:

• Sequencing of a cDNA library from the plasmodial stage.
• Identification of genes for basic metabolism, signaling networks, and environmental signal receptors.
• Determination of splicing signatures using donor and acceptor sites.

Main Results:

• An unexpectedly large number of genes involved in sophisticated signaling networks were identified.
• Potential receptors for environmental signals, such as light, were found.
• Many P. polycephalum genes exhibit alternative splicing, with defined splicing signatures.
• Approximately half of the transcribed genes lack detectable counterparts in other organisms, suggesting species-specific adaptations.
• Highly conserved proteins, present in metazoans but absent in Dictyostelium discoideum or plants, were identified, potentially originating from the ancestor of Amoebozoa and Metazoa.

Conclusions:

• This work analyzes up to half of the protein-coding genes of P. polycephalum.
• The defined splice motifs and alternatively spliced genes offer a valuable resource for the ongoing genome project.
• The findings contribute to understanding eukaryote evolution and the unique adaptations of P. polycephalum.