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Monday, 16 September 2019 

Life Sciences

In the International Space Station (ISS), various countries are pooling their knowledge to conduct a wide variety of research for the future benefit of the human race. 

Presently, each country is constructing various experiment systems. One of the core life science experiment systems being developed for the ISS is the Centrifuge.

C. Elegans               
What are these worms? They are tiny nematodes called Caenorhabditis Elegans. An adult is about 1 millimetre long - about as long as a grain of salt is wide. C. Elegans has many advantages as a model system for studying the effects of radiation in space. One advantage is its small size. A C. Elegans experiment doesn't need much room. This is important because it's expensive to launch weight into orbit and spacecraft, even the ISS, are very cramped. In addition, C. Elegans has a generation time of just a few days; a two-week lifespan in which a single hermaphrodite produces about 300 offspring; a limited number of cells (less than 1,000); and it's easy to maintain in a laboratory. These advantages mean that experimental procedures can be short, flexible and cost effective. The worms can be kept in little bags so that the astronauts can just inject liquid food into the bags every few weeks. 

Another advantage is that C. Elegans is the simplest multi-cellular organism with a completely known genomic DNA sequence. Like humans, C. Elegans has about 20,000 genes. About 4,500 of these genes are effectively doing the same jobs in worms as in humans. These similar genes include a large set whose job is to repair DNA damage. Not only does C. Elegans have a similar number of genes to us, they have a lot of effectively the same genes and similar DNA repair systems, making C. Elegans an excellent model for learning about potential biological damage to humans in the space environment. 

C. Elegans has already been to space on several missions. These include the 1993 and 1996 flights that carried experiments for Greg Nelson of the Jet Propulsion Laboratory (JPL); the 2003 Columbia flight, which crashed in Texas and carried experiments for Nate Szewczyk of the University of Pittsburg and Catharine Conley of NASA's Ames laboratory; and the 2004 First International C. elegans experiment (ICE-first) on the Delta mission in which Ann Rose, an SFU alumna, headed the Canadian Space Agency(CSA)-funded part of the four-country collaboration (Canada, France, Japan and the U.S.). 

Believe it or not, live worms were recovered from the disaster of the Columbia. They survived an impact 2,295 times the force of Earth's gravity. "This is a very exciting result," said Catharine Conley of NASA (Astrobiology Article 1921). "It's the first demonstration that animals can survive a re-entry event similar to what would be experienced inside a meteorite. It shows directly that even complex small creatures originating on one planet could survive landing on another without the protection of a spacecraft." 
The two JPL experiments and ICE-first used a C. Elegans mutagen testing system developed in SFU professor David Baillie's NSERC-funded SFU laboratory by research associate Raja Rosenbluth and grad student Bob Johnsen, now a research associate. Called the eT1-system (named before the movie ET came out), the system can capture mutations in C. Elegans' genome for analysis on the ground after a completed spaceflight. 

Like us, C. Elegans has two sets of chromosomes, so even if there is a mutant gene on one chromosome the normally functioning gene on the other is usually sufficient to perform that gene's function. The offspring of a worm with a mutant gene will get either the mutant or the normal gene. Because the normal gene does an important job while the mutant doesn't, over the generations worms with the normal gene will out-compete mutant worms and the mutation is eventually lost. This loss is not good if you want to analyse space radiation-induced genetic damage. The eT1 system maintains mutations so they won't be lost. 

While the first worms-in-space experiments were for short-time (about one generation) exposure to space radiation during the JPL flight, the ICE-first experiment was for a little longer - 11 days in space. These short experiments yielded only a few mutations, not much above the number of spontaneous mutations we would expect on Earth. 

This is likely because satellites in low Earth orbit, including the ISS, are protected by the Earth's magnetosphere. Trips to the Moon or Mars will last a lot longer and will not be protected by the magnetosphere. Nobody knows what biological effects these long trips will have on humans. 

We will use the eT1 system to get an accurate assessment of the biological effects of long exposure to radiation on the ISS and from this we'll develop a biological accumulating dosimeter for longer trips. 

Two of our research questions: How do biological systems respond to fluctuating dosages of different types of radiation in space? Do DNA repair systems work differently in space than on Earth? We will look at multi-generational effects (which can't be done with humans) by placing C. Elegans on the ISS for several months. Our current plan is to fly the worms to the ISS in 2007-08. We are also having discussions with TRIUMF, located at UBC, to expose eT1-system worms to radiation in its particle accelerator, simulating the ISS environment. 

Once we have radiation-exposed worms back at SFU we'll use newly developed Nimblegen DNA-array chip technology to analyse the worms. These chips contain bits of DNA from C. Elegans' 20,000 genes, so by comparing the exposed worms with the chips we'll be able to rapidly identify any mutations. 



Article C. Elegans


C. Elegans

Protein Crystallization in Space
The microgravity environment of space is an ideal place to study the complicated protein crystallization process and to grow good-quality protein crystals. A series of crystal growth experiments of 10 different proteins was carried out in space on a Chinese re-entry satellite FSW-2 in August, 1992. 

The experiments were performed for about two weeks at a temperature of 18.5 +/- 0.5 degrees C using a tube-like crystallization apparatus made in the Shanghai Institute of Technical Physics, Academia Sinica. More than half of 48 samples from 6 proteins produced crystals, and the effects of microgravity on protein crystal growth were observed, especially for hen-egg white lysozyme and an acidic phospholipase A2 from the venom of Agkistrodon halys Pallas. 

Analyses of the crystallization of these two enzymes in this mission showed that the microgravity environment in space may be beneficial to improve size, external perfection, morphology, internal order, and nucleation of protein crystals. Some of these positive microgravity effects were also demonstrated by the growth of protein crystals in gelled solution with the above two enzymes. A structural analysis of the tetragonal lysozyme crystal grown in space is in progress.



Article Protein in Space

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