10 Feb Magnetically enabled simulation of microgravity on a microfluidic chip

“For plants on Earth, the phytohormone auxin is essential for gravitropism-regulated seedling establishment and plant growth. However, little is known about auxin responses under microgravity conditions due to the lack of a tool that can provide an alteration of gravity. In this paper, a microfluidic negative magnetophoretic platform is developed to levitate Arabidopsis seeds in an equilibrium plane where the applied magnetic force compensates for gravitational acceleration. With the benefit of the microfluidic platform to simulate a microgravity environment on-chip, it is found that the auxin response is significantly repressed in levitated seeds. Simulated microgravity statistically interrupts auxin responses in embryos, even after chemical-mediated auxin alterations, illustrating that auxin is a critical factor that mediates the plant response to gravity alteration. Furthermore, pretreatment with an auxin transportation inhibitor (N-1-naphthylphthalamic acid) enables a decrease in the auxin response, which is no longer affected by simulated microgravity, demonstrating that polar auxin transportation plays a vital role in gravity-regulated auxin responses. The presented microfluidic platform provides simulated microgravity conditions in an easy-to-implement manner, helping to study and elucidate how plants correspond to diverse gravity conditions; in the future, this may be developed into a versatile tool for biological study on a variety of samples.”

” On-site monitoring of Arabidopsis seeds by implementing a camera on a slide toward the microfluidic device. b Schematic of the microfluidic chip with five channels for seed cultivation. Each channel (10 mm in length, 2 mm in width, and 100 μm in height) has two cultivation reservoirs (1000 μm in diameter, 2 mm in depth) that are cut through the PDMS layer. c Photograph of the microfluidic negative magnetophoresis platform. Two permanent magnets are assembled beneath the glass substrate, and the inner edges are aligned to the cultivation reservoirs. d The experimental procedures. First, the seeds are put into the cultivation reservoirs, and the culture medium is injected into microchannels. Second, the culture medium was replaced by Gd³⁺ solution. Third, the seeds are lifted and maintained at the position by negative magnetophoresis. Finally, PEG-DA and Gd³⁺ solutions are injected into the channels and cured by ultraviolet radiation” Reproduced under Creative Commons Attribution 4.0 International License from Du, J., Zeng, L., Yu, Z. et al. A magnetically enabled simulation of microgravity represses the auxin response during early seed germination on a microfluidic platform. Microsyst Nanoeng 8, 11 (2022). https://doi.org/10.1038/s41378-021-00331-5 

Figures and the abstract are reproduced from Du, J., Zeng, L., Yu, Z. et al. A magnetically enabled simulation of microgravity represses the auxin response during early seed germination on a microfluidic platform. Microsyst Nanoeng 8, 11 (2022). https://doi.org/10.1038/s41378-021-00331-5 under Creative Commons Attribution 4.0 International License

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