2012/11/22 by Karl H. Hasenstein, Susan John, Susan P. John +5 · 20 citations
Biochemistry, Genetics and Molecular Biology · Engineering · Medicine · #Agricultural Engineering and Mechanization #Amyloplast #Astrobiology #Biochemistry #Biology #Biomagnetism #Biophysics #Diamagnetism #Gravitropism #Hypergravity #Magnetic and Electromagnetic Effects #Magnetic field #Materials science #Physics #Plastid #Potential gradient #Spaceflight effects on biology #Starch #Weightlessness
paper · doi:10.3732/ajb.1200304
published in American Journal of Botany 100(1), 249-255 (Wiley)
openalex publication_date 2012/11/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/22
PREMISE OF THE STUDY: Gravitropism typically is generated by dense particles that respond to gravity. Experimental stimulation by high-gradient magnetic fields provides a new approach to selectively manipulate the gravisensing system. METHODS: The movement of corn, wheat, and potato starch grains in suspension was examined with videomicroscopy during parabolic flights that generated 20 to 25 s of weightlessness. During weightlessness, a magnetic gradient was generated by inserting a wedge into a uniform, external magnetic field that caused repulsion of starch grains. The resultant velocity of movement was compared with the velocity of sedimentation under 1 g conditions. RESULTS: The high-gradient magnetic fields repelled the starch grains and generated a force of at least 0.6 g. Different wedge shapes significantly affected starch velocity and directionality of movement. CONCLUSIONS: Magnetic gradients are able to move diamagnetic compounds under weightless or microgravity conditions and serve as directional stimulus during seed germination in low-gravity environments. Further work can determine whether gravity sensing is based on force or contact between amyloplasts and statocyte membrane system.