Cambium (Cambium) - 08.05.15

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
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.
Science Results for Everyone
Information Pending

The following content was provided by Rodney Savidge, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Rodney Savidge, Ph.D., University of New Brunswick, Fredericton, Canada

Information Pending

NASA Kennedy Space Center, Cape Canaveral, FL, United States
Bionetics Corporation, Cape Canaveral, FL, United States

Sponsoring Space Agency
Canadian Space Agency (CSA)

Sponsoring Organization
Information Pending

Research Benefits
Information Pending

ISS Expedition Duration
October 2009 - March 2010

Expeditions Assigned

Previous 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.

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Experiment Description

Research Overview

  • The Cambium payload is the first flight of the Advanced Biological Research System (ABRS) facility. The ABRS provides two independent growth volumes capable of providing illumination, thermal control, atmospheric constituent control, and relative humidity control for a variety of plants, microorganisms, or other biological specimens.

  • The Cambium research is needed to help understand the fundamental processes by which plants produce cellulose and lignin, the two main structural materials found in plant matter.

  • On Earth, various portions of a plant can have physically different compositions including different ratios of lignin and cellulose. One such plant material is called ‘reaction wood’. It is believed that this reaction wood may develop in response to the influence of gravity.

  • In the Cambium experiment, willow plants will be launched into space and then their stems will be curled into loops in an attempt to induce reaction wood formation. After some amount of additional growth in space, the plants will be preserved for analysis back on Earth to determine whether or not reaction wood was created in the absence of gravity.

  • Understanding the role of cellulose and lignin production may enable researchers to control these materials in trees on Earth making those trees more suitable for paper production (more cellulose) or construction strength (more lignin).

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.

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Space Applications
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.

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Operational Requirements
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.

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Results/More Information

Information Pending

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Related Websites

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image Image of the Cambium looping tool prototype. Image provided by the Canadian Space Agency.
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image Looped willow plant and photogrid. Image provided by The Bionetics Corporation, Kennedy Space Center, FL
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image NASA Image: ISS022E005350 - View of plants in the U.S. Laboratory. Photo was taken during Expedition 22.
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image CSA Astronaut and Expedition 20/21 crew member Bob Thirsk poses with the Canadian willow trees that were used for the APEX CAMBIUM experiment. These trees have been preserved and frozen, and will return to Earth on STS 130. (Photo: NASA).
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Microscopic view of reaction wood fibers as formed on Earth. This is a cross-section of a willow stem that has been 'looped' to stimulate formation of reaction wood. The reaction wood zone is indicated by a red line. (Photo: CSA)

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image A weeping willow in St. Bruno de Montarville, Québec, 4 kilometers from the headquarters of the Canadian Space Agency. Weeping willow shoots were used in the APEX CAMBIUM experiment.(Photo: CSA)
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image NASA Image: ISS023E036876 - Expedition 23 flight engineer T.J. Creamer harvests the white spruce seedlings to close out the Advanced Plant Experiments on Orbit - Canadian Space Agency 2 (APEX-CSA2) experiment.
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image NASA Image: ISS023E025847 - NASA astronaut T.J. Creamer, Expedition 23 flight engineer, services the Advanced Plant Experiments on Orbit-Cambium (APEX-Cambium) experiment in the Columbus laboratory of the International Space Station.
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