Stress response of Caenorhabditis elegans induced by space crowding in a micro-column array chip.

Crowding stress has been reported to play an important role in affecting physiological behaviour. To study this process, a reliable analytical method under confined space is essential. In this work, we demonstrated a microfluidic approach for investigating physiological responses of C. elegans to confined spaces. The PDMS microfluidic chip consisting of arrays of micro-columns enabled us to mimic different crowding conditions by changing the intervals among micro-columns. C. elegans were transferred into this micro-column array and the subcellular distribution of DAF-16, which is a well-known transcription factor regulating different stress responses, was monitored for analysing the physiological responses to the confined spaces. We found that the worms exhibited a gradual increase in DAF-16 nuclear localization in the micro-column array with intervals from 200 μm to 40 μm. Moreover, the results showed that the absence of food and crowding stress could cooperate to promote increased DAF-16 nuclear localization. Finally, loss-of-function mutations in mec-4 and mec-10, which are amiloride-sensitive Na(+) channel genes expressed in all six gentle touch neurons, accelerated the velocity of DAF-16 nuclear localization, induced by confined space, revealing that mec-4/mec-10 were not required for this stress response. Thus, this device will provide a versatile, reliable and controllable platform for crowding stress studies.