Stable nuclear transformation of Gonium pectorale

Area of Science:

• Algal molecular biology
• Evolutionary developmental biology
• Genetics

Background:

• The Volvocaceae family, including Gonium, serves as a model for studying multicellularity.
• Gonium represents an intermediate complexity between unicellular and multicellular volvocine algae.
• Genetic manipulation methods were previously limited to Chlamydomonas reinhardtii and Volvox carteri.

Purpose of the Study:

• To establish a stable nuclear transformation protocol for Gonium pectorale.
• To enable genetic engineering of Gonium for molecular evolution studies.
• To assess the efficacy of heterologous gene expression in Gonium.

Main Methods:

• Stable nuclear transformation of G. pectorale via particle gun bombardment.
• Utilized a heterologous aminoglycoside 3'-phosphotransferase VIII (aphVIII) gene as a selectable marker.
• Employed heterologous 3'- and 5'-untranslated flanking sequences from C. reinhardtii and V. carteri.

Main Results:

• Achieved stable integration of plasmids into the Gonium genome, verified over 1400 generations.
• Demonstrated successful heterologous gene expression, including a codon-optimized Gaussia princeps luciferase reporter gene.
• Obtained co-transformants at 30-50% frequency, confirming the utility of Gonium for studying gene function.

Conclusions:

• Heterologous promoters from C. reinhardtii and V. carteri facilitate functional gene expression in G. pectorale.
• The established transformation method makes Gonium genetically engineerable.
• This advancement facilitates comparative molecular evolution studies across the unicellular-to-multicellular spectrum in Volvocaceae.