The Cambium investigation is one in a pair of investigations which utilizes the Advanced Biological Research System (ABRS). Cambium seeks definitive evidence that gravity has a direct effect on cambial cells (cells located under the inner bark where secondary growth occurs) in willowSalix babylonica.Principal Investigator(s)
Bionetics Corporation, Cape Canaveral, FL, United States
Kennedy Space Center, , FL, United States
Canadian Space Agency (CSA)Sponsoring Organization
Information PendingResearch Benefits
Information PendingISS Expedition Duration
October 2009 - March 2010Expeditions Assigned
21/22Previous ISS Missions
Cambium is scheduled to arrive on the ISS during the 17A mission. Expedition 19/20 is the first mission for the Cambium investigation.
The Cambium experiment will provide an understanding of physiological processes such as gene expression, metabolism and general plant development that are affected in plant systems exposed to space flight. Cambium seeks definitive evidence that gravity has a direct effect on the cambial cells (cells located under the inner bark where secondary growth occurs) that contribute to xylogenesis (reaction wood formation) in willow plants, Salix babylonica. Tension wood fibers differentiate on the upper sides of stems when the stem is altered from its normal (vertical) growth position by looping. This reaction wood response does not occur if the orientation of the plant stem with respect to gravity is not altered. If a localized zone of tension wood should be formed in looped stems under microgravity conditions, this would be the first conclusive evidence that gravity is not required. On the other hand, if a zone of tension wood is not produced in looped stems (subjected to tension on one side, compression on the other) in microgravity, this would be the first definitive evidence that gravity has a direct effect on the cambial cells which contribute to reaction wood formation. Following return to Earth the plants will be analyzed by microscopy and chemical methods.
Cambium along with the ABRS hardware demonstrates the capabilities of providing the correct environment for plant growth onboard spacecraft. For future long-duration exploration, crews will need to be able to grow plants for a variety of applications.Earth Applications
Understanding the fundamental processes by which plants produce cellulose and lignin in their tissues is of great interest in the realm of forestry and industry. Trees used for paper production are selected for maximum cellulose production and minimal lignin production. Conversely, trees used to make structural lumber are selected for maximum lignin content. However, due to the complex relationship of these two biosynthesis processes, researchers do not yet know how to genetically alter such plants to further boost their productivity.
Cambium requires a controlled environment provided by the ABRS facility which also provides images that are downlinked to the ground teams. The crew is responsible for stem looping, harvesting, reinitialization, water refill, and changing out the air filter. After harvesting, parts of the samples are chemically preserved and stored in the Minus Eighty-Degree Laboratory Freezer for ISS (MELFI).Operational Protocols
The crew is responsible for performing the stem looping of the plants by using a looping tool that fashions a loop of reproducible size followed by application of a restraining tape to maintain the looped configuration. After the growth period the plants are harvested by cutting the looped stem and analogous unlooped stems from control plants. These stem portions are then placed into KSC fixation tubes (KFTs) containing chemical preservatives and stored at ambient conditions or frozen in MELFI.
To maintain the environment in the ABRS the crew uses a syringe to transfer approximately 60-mL of water from the ISS potable water source to each of two quick disconnect fittings associated with the two reservoirs inside the ABRS. Air filter change out is performed by opening the front hatch of the ABRS locker, loosening a Velcro restraining strap, and pulling each of the two filters off of the back side of the hatch. There are blind mate connectors on the back side of each filter.