Amplification of chromosome 6 restores the ability of an <i>mfg1Δ/mfg1Δ</i> mutant to filament.

A) Independent colonies from an mfg1Δ/mfg1Δ mutant expressing the NAT (nourseothricin) resistance marker from the HWP1 promoter were plated on solid YPD containing 10% serum and 250 μg/mL NAT and grown at 37°C for 2 days. Shown are three independently evolved mutants that were able to filament in liquid conditions in response to serum (Evo #A1, Evo #A2, and Evo #A3). Cells were grown in YPD at 30°C or in YPD with 10% serum at 37°C for 6 hours. Scale bar is 20 μm. B) The genomes of three independently evolved filamentous mutants (Evo #A1, Evo #A2 and Evo #A3) in the mfg1Δ/mfg1Δ background were sequenced and profiled for copy number variants using YMAP. C) Deletion of one allele of FLO8 from the evolved mutant Evo #A2 impairs its ability to filament. One allele of FLO8 was replaced with CdARG4, and cells were grown as in A). Scale bar is 20 μm.