Whether you're a researcher wishing to study living insects in conditions requiring a lethal vacuum, or you're that insect in the vacuum simply wishing not to die, scientists have found a solution to your problem. Using only a common chemical and a scanning electron microscope (SEM), a team at the Hamamatsu University School of Medicine developed a process that allows insects to survive in a vacuum of about a millionth of atmospheric pressure. Not just a new technique in biologists' toolkit, this research adds a small piece to our understanding of how life – insect, human, or otherwise – might be sustained outside the narrow constraints our bodies demand.
The discovery hinges on the two main components of an SEM microscope: an extreme vacuum and an electron beam. Generally insects are killed and preserved to prepare them for microscopy, but the team decided to compare how different living insects fared under the vacuum. They noted with surprise that even after an hour in the vacuum, fruit fly larvae were still wriggling, seemingly unperturbed by their conditions. Yet, when other larvae were placed in the vacuum without the beam, they quickly succumbed.
After comparing those two groups of insects, living and dead, it became apparent the larvae exposed to the electron beam sported an extra layer of impassable but flexible material that protected them from the desiccating effects of the vacuum. The team dubbed this protective layer a "nano-suit," so named because the extra layer is only 50-100 nm thick. The source of this layer? Fruit fly larvae and some other insects naturally secrete a goop (extracellular substances, or ECS). These substances polymerized when provided the extra energy input of the beam.
Yet most insects don't have ECS, and indeed, even under the electron beam these insects unsurprisingly and quickly died. However, a coating of a detergent called Tween-20 was found to have similar properties as insect goop when followed with the same radiation treatment. Almost as quickly as the natural nano-suit was born, the artificial nano-suit joined the ranks. Both suits kept the insects alive for an hour in a vacuum.
While the results may seem exciting in regards to human applications, the difference in scale between insect larvae and humans isn't the only obstacle. The polymerized nano-suit protects in a vacuum, yet ironically to obtain the suit, the insect larvae endured ionizing radiation and even with the nano-suit lost about a tenth of their body weight. Humans aren't likely to be dipping themselves in detergent and radiating themselves anytime soon.
The true implications are more subtle and are hinted at by the paper's authors. Beyond providing a useful microscopy technique for researchers, it's surprising that the lab so easily mimicked extremophiles (i.e. organisms that thrive in conditions that are too extreme to support our own physiological needs). The authors also hint that naturally occurring sources of ionizing radiation could inadvertently protect small organisms caught in space travel between planets, an interesting thought for those of who wonder if life can be supported elsewhere in the universe.
Source: PNAS, via BioTechniques
