Something stirs in a fog filled glass compartment set in a futuristic looking spaceship cabin, camera zooms in on the face of ashen looking human face, uncomprehending eyes blink and open, the astronaut stirs to life as the compartment lid opens and the befuddled looking human emerges, showing first signs of comprehension………
Science-fiction (or comedy) has the scenario worked out, but how close is real science getting to its realization? Understanding cryptobiosis and paying for such research is the only path to achieving this goal. Many living organisms on Earth have evolved to withstand conditions unsuitable to life as we humans understand it. Humans and most earthly organisms require water, food, suitable temperature, and plentiful oxygen in the atmosphere. But oddities and exceptions exist among many of the “lower” life forms, from bacteria to yeasts, plants and insects.
To me, the most interesting is the ability to survive long periods without water (dehydration, desiccation) or anhydrobiosis. Mosses may not be the most currently suitable experimental system for studying this phenomenon due to lack of understanding of their genetics, but fate brought me into the lab of Dr. Derek Bewley for my MSc degree, so these will be my focus.
The fundamental issue faced by desiccation tolerant organism is the maintenance of structural integrity – this means maintaining a working relationship between macromolecules which make up the cellular structure. In “normal” situation, such molecules are surrounded by plenty of water which “hydrates” the surfaces, allows for the formation of the membrane phospholipid bilayers, and serves as a solvent for the movement and delivery of essential cellular components during the normal “living” or “growing” phase of the organism’s life. As water is lost to the organism by evaporation or drawn out by surrounding ice, it is generally understood that other molecules which to some extent mimic or substitute for the HOH structure of water. These tend to be sugars or alcohols, molecular structures surrounded by OH “functional groups”. In some organisms seasonal metabolic (read “molecular”) adjustments are needed to go from the “growing” to “tolerant” stages. But many slow growing organisms (such as mosses or lichens) are ever ready to face adverse conditions by always investing energy and resources into the synthesis of protective molecules of the “survival mode”.
While scientists have worked out many of the protective
biochemical/molecular mechanisms which permit the anhydrobiosis stage survival,
the problem of maintaining structural integrity is fundamentally biophysical
one, and an area of scientific endeavour for which many biology students are
not prepared. New techniques are being developed, which will allow direct
visualization of the dehydration process, as well as methods for indirect
probing of the molecular interactions during the de- a re-hydration phases. New
generation of scientists is needed to address these fascinating questions, but
many of these methods will rely on expensive instrumentation, which will only be
available at large institutions and used by teams of scientists from
disciplines other than biology.
Where would I go and what would I do if I had to start answering anhydrobiosis questions now? How would I fund my research? Peter Medawar has written an excellent little tome “Advice to a Young Scientist” (copy available in herbarium library). Even though written in the 1950’s much of his insight is still topical. But times have changed in respect to funding of basic, curiosity driven research. Nowadays it helps to persuade the funding agencies and their granting panels of scientists that the proposed research will have some direct benefit to humanity. So even though the best experimental “model” organisms are the ones with well understood genetics (bacteria, yeasts and Caenorhabditis – all desiccation tolerant), desiccation and cryopreservation of human cells and tissues offer a “back door” route to justifying one’s inquiries into cryptobiosis. (Reproductive cell cryopreservation is well funded, but contributes to overpopulation - more on this elsewhere). The Canadian research establishment tends to be too small to support programs, and one would have to return to Canada after establishing a career abroad as a post-doctoral fellow in a well established cryptobiosis laboratory. Unless applying to NASA or International Space Agency, I would not push the fictional space travel angle. Preserving whole human bodies proposal would definitely be extreme, unless applying to a wealthy benefactor, who wishes to become immortal and expects future science to be able to resurrect his/her body. In the grand scheme of things, more pressing issues related to global warming and suppressing the human reproductive instinct may be given funding preference in the not so distant future. Alternatively, the day may come when degradation of Earth ecosystems renders the planet barely habitable to humans, anhydrobiosis and cryptobiosis research may become essential for human species survival on Earth. (For more optimistic essays, see here in the future).