Microbeam irradiation of C. elegans nematode in microfluidic channels
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To perform high-throughput studies on the biological effects of ionizing radiation in vivo, we have implemented a microfluidic tool for microbeam irradiation of Caenorhabditis elegans. The device allows the immobilization of worms with minimal stress for a rapid and controlled microbeam irradiation of multiple samples in parallel. Adapted from an established design, our microfluidic clamp consists of 16 tapered channels with 10-μm-thin bottoms to ensure charged particle traversal. Worms are introduced into the microfluidic device through liquid flow between an inlet and an outlet, and the size of each microchannel guarantees that young adult worms are immobilized within minutes without the use of anesthesia. After site-specific irradiation with the microbeam, the worms can be released by reversing the flow direction in the clamp and collected for analysis of biological endpoints such as repair of radiation-induced DNA damage. For such studies, minimal sample manipulation and reduced use of drugs such as anesthetics that might interfere with normal physiological processes are preferable. By using our microfluidic device that allows simultaneous immobilization and imaging for irradiation of several whole living samples on a single clamp, here we show that 4.5-MeV proton microbeam irradiation induced DNA damage in wild-type C. elegans, as assessed by the formation of Rad51 foci that are essential for homologous repair of radiation-induced DNA damage.
KeywordsMicrobeam irradiation with microfluidic devices C. elegans microbeam irradiation Small animal microbeam irradiation Rad51 foci in C. elegans
This work was supported by the National Institute of Biomedical Imaging and Bioengineering (NIBIB) under Grant: 5 P41 EB002033 and an EMBO long-term fellowship and HFSPO long-term fellowship to M.G. We are grateful to the Caenorhabditis Genetics Center for providing the mutant strain. We thank the RARAF team for their scientific support and advice.
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