Plants in space: A novel method for fixing plant tissue samples maximizes time, resources, and data

Sep 11, 2013
This is a SEM image of Arabidopsis tissue processed using the new single fixation protocol developed by Schultz et al. Pictured is the adaxial leaf epidermis (3500x, scale bar = 8.57 μm). Credit: Image courtesy of Schultz et al.

At work on the International Space Station, researchers studying plant and cell growth in space encountered a challenge. Imaging revealed interesting spaceflight-associated root morphologies. They needed to fix the tissues for further study back on Earth, but conventional fixation methods require separate fixatives depending on whether the sample is intended for molecular or morphological study. If the scientists wanted to study how spaceflight affected patterns of gene expression central to morphological patterns of cell growth, they needed a fixation method that would allow them to study both perspectives.

Most scientists at work in the laboratory rely on protocols that have been developed without the need for restrictions on the amount of space, time, or reagents they use. For scientists conducting experiments in spaceflight, time and resources are strictly regulated and limited, and researchers must know in advance which protocols will maximize the usefulness of the data they collect.

University of Florida professors Anna-Lisa Paul and Robert Ferl and colleagues are collaborating with the National Aeronautics and Space Administration (NASA) to understand plant growth and development in spaceflight. Along with lead author and graduate student Eric Schultz, they have developed a single fixation protocol for use in space that allows plant material to be used for multiple experimental applications. Their new protocol for sample preparation was tested on Arabidopsis tissues harvested on the International Space Station and is described in the August issue of Applications in Plant Sciences (available for free viewing at http://www.bioone.org/doi/pdf/10.3732/apps.1300034).

Because of limitations in astronaut crew time and orbital resources, previous spaceflight fixation protocols were designated as either molecular or morphological, due to the separate fixatives required for each application. Tissues for morphologic study were fixed in 3% glutaraldehyde (or a similar solution), and tissues for molecular study were fixed in the tissue storage reagent RNAlater. RNAlater has not commonly been used as a morphologic fixative, as it can produce unclear images with high background staining.

The new method developed by Schultz et al. puts RNAlater-fixed samples through a desalination process to return them to a fresh-like state, and then uses low-temperature scanning electron microscopy (cryo-SEM) to preserve tissues for imaging. Because few laboratories have access to the necessary equipment for cryo-SEM, the authors tested and developed a protocol that emulates cryo-SEM using standard SEM equipment and, importantly, that results in minimal tissue damage.

Although it was developed to address specific constraints for spaceflight experiments, Paul notes that their new method is broadly applicable. "There are a lot of situations where biologists want to collect samples in extreme situations. In our case—a space vehicle orbiting the Earth."

The new protocol maximizes the amount of data obtained from a single sample and allows for the concomitant examination of both molecular and morphological features. Using a single fixation protocol, direct comparisons between changes in morphology and altered can be made. Such an analysis not only makes full use of samples and replicates but also enables a robust analysis of the relationship between heredity and development. "Putting two tools together, it is powerful to look at the morphology in conjunction with the genes that are being expressed," says Paul.

The new protocol boasts low costs and high accessibility, and has wide application to any situation where recovery of biological resources is limited. Notably, this includes researchers collecting and preserving samples in the field, where for materials is at a premium. "In places where sampling is limited, difficult, or expensive, the use of preservatives allows for more routes to analysis," notes Ferl.

Explore further: Study shows starving mantis females attract more males

add to favorites email to friend print save as pdf

Related Stories

Space station boosting biological research in orbit

Aug 13, 2013

Studying the science of biology in microgravity opens a world of possibilities! Research ranges from plant growth to cell growth and from bacterial virulence to strength in human bones. The scope of biology ...

What happens to plant growth when you remove gravity?

Dec 07, 2012

It is well known that plant growth patterns are influenced by a variety of stimuli, gravity being one amongst many. On Earth plant roots exhibit characteristic behaviours called 'waving' and 'skewing', which ...

Spaceflight alters bacterial social networks

Aug 15, 2013

When astronauts launch into space, a microbial entourage follows. And the sheer number of these followers would give celebrities on Twitter a run for their money. The estimate is that normal, healthy adults ...

Predicting cancer prognosis

Aug 27, 2009

Researchers led by Dr. Soheil Dadras at the Stanford University Medical Center have developed a novel methodology to extract microRNAs from cancer tissues. The related report by Ma et al, "Profiling and discovery of novel ...

Recommended for you

Big data and the science of the Christmas tree

29 minutes ago

Often called the "Cadillac of Christmas trees," the Fraser Fir has everything a good Christmas tree should have: an even triangular shape, a sweet piney fragrance, and soft needles that (mostly) stay attached ...

Study shows starving mantis females attract more males

22 hours ago

A study done by Katherine Barry an evolutionary biologist with Macquarie University in Australia has led to the discovery that a certain species of female mantis attracts more males when starving, then do ...

African swine fever threatens Europe

Dec 17, 2014

African swine fever, or ASF, is a viral disease that kills almost every pig it infects and is likened to Ebola. It gained a foothold in Georgia in 2007, when contaminated pig meat landed from a ship from ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.