Diamagnetic levitation changes growth, cell cycle, and gene expression of Saccharomyces cerevisiae

Abstract Inhomogeneous magnetic fields are used in magnetic traps to levitate biological specimens by exploiting the natural diamagnetism of virtually all materials. Using Saccharomyces cerevisiae , this report investigates whether magnetic field ( B ) induces changes in growth, cell cycle, and gene expression. Comparison to the effects of gravity and temperature allowed determination of whether the responses are general pathways or stimulus specific. Growth and cell cycle analysis were examined in wild‐type (WT) yeast and strains with deletions in transcription factors Msn4 or Sfp1. Msn4, Sfp1, and Rap1 have been implicated in responses to physical forces, but only Msn4 and Sfp1 deletions are viable. Gene expression changes were examined in strains bearing GFP‐tagged reporters for YIL052C (Sfp1‐dependent), YST‐2 (Sfp1/Rap1‐dependent), or SSA4 (Msn4‐dependent). The cell growth and gene expression responses were highly stimulus specific. B increased growth only following Msn4 or Sfp1 deletion, associated with decreased G1 and G2/M and increased S phase of the cell cycle. In addition, B suppressed expression of both YIL052C and YST2. Gravity decreased growth in an Sfp1 but not Msn4‐dependent manner, in association with decreased G2/M and increased S phase of the cell cycle. Additionally, gravity decreased expression of SSA4 and YIL052C genes. Temperature increased cell growth in an Msn4‐ and Sfp1‐dependent manner in association with increased G1 and G2/M with decreased S phase of the cell cycle. In addition, temperature increased YIL052C gene expression. This study shows that B has selective effects on cell growth, cell cycle, and gene expression that are stimulus specific. Biotechnol. Bioeng. 2007; 98: 854–863. © 2007 Wiley Periodicals, Inc.