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Topic Name: Searching for Evidence of Life on Mars or Other Planets New Research Finds Cellulose Microfibers

Category: STAR (Space, Telecommunications & Radioscience)

Research persons: Jack D. Griffith, Ph.D., Kenan

Location: University of North Carolina at Chapel Hill, United States

Details

Looking for evidence of life on Mars or other planets? Finding cellulose microfibers would be the next best thing to a close encounter, according to new research from the University of North Carolina at Chapel Hill.

The cover story for the April issue of the journal Astrobiology, the new research also pushes back the earliest direct evidence of biological material on Earth by about 200 million years.

Cellulose is the tough, resilient substance best-known as the major structural component of plant matter. It is one of the most abundant biological materials on Earth, with plants, algae and bacteria generating an estimated 100 gigatons each year. Prehistoric forms of cellulose were made by cyanobacteria, the blue-green algae and bacteria still found in almost every conceivable habitat on land and in the oceans, which is known to have been present on Earth 2.8 billion years ago.

Jack D. Griffith, Ph.D., Kenan Distinguished Professor of microbiology and immunology at the UNC School of Medicine, found cellulose microfibers in samples he took from pristine ancient salt deposits deep beneath the New Mexico high desert.

“The age of the cellulose microfibers we describe in the study is estimated to be 253 million years old. It makes these the oldest native macromolecules to date to have been directly isolated, visualized and examined biochemically,” said Griffith, who is also a virology professor at the UNC Lineberger Comprehensive Cancer Center.

Until now, the oldest evidence of biological material from fragments of ancient protein – found in Tyrannosaurus Rex dinosaur fossils – was dated at 68 million years.

According to Griffith, the most primitive life forms likely developed means of polymerizing glucose – the energy currency of all known carbon-based life forms – into cellulose as a structural molecule. “Cellulose is like the bacteria’s house, the biofilm surrounding them. Plants adopted cellulose as their structural entity, and insects changed cellulose slightly to make kitin of which their exoskeletons are formed,” he said.

Griffith’s study took him to the U.S. Department of Energy’s Waste Isolation Pilot Plant (WIPP), the world’s first underground repository licensed to safely and permanently dispose of radioactive waste left over from nuclear weapons research and production, which is located near Carlsbad, N.M.

The waste is placed more than 2,000 feet below the surface in rooms excavated from the salt deposits that were laid more than 200 million years ago. The site was chosen to hold the waste because salt is somewhat plastic and will flow to seal any cracks that develop.

The salt samples Griffith retrieved from the WIPP were studied in his transmission electron microscopy lab at the Lineberger Comprehensive Cancer Center. In examining the content of fluid “inclusions”, or microscopic bubbles, in the salt and in solid halite (“rock salt”) crystals, he and his team found abundant cellulose microfibers that were “remarkably intact.”

Their examination clearly revealed the cellulose was in the form of microfibers as small as five nanometers in diameter, as well as composite ropes and mats. “The cellulose we isolated from the ancient salt deposits is very much like real, modern day cellulose: it looks like cellulose, behaves like cellulose, it’s chopped up by the same enzymes that cut modern day cellulose and it’s very intact,” Griffith said.

As to evidence of ancient DNA, Griffith said it was observed, but in much lesser amounts than cellulose.

“So in looking for evidence of life on Mars, for bacteria or higher plants that existed on Mars or other planets in the solar system, then looking for cellulose in salt deposits is probably a very good way to go. Cellulose appears to be highly stable and more resistant to ionizing radiation than DNA. And if it is relatively resistant to harsh conditions such as those found in space, it may provide the ideal ‘paper trail’ in the search for life on other planets.”

Note for Microfiber
Microfiber is fiber with strands less than one denier. Microfiber is a blend of polyester and polyamide. Fabrics made with microfibers are exceptionally soft and hold their shape well. When high quality microfiber is combined with the right knitting process, it creates an extremely effective cleaning material. This material can hold up to seven times its weight in water. They are also used for some cleaning applications, because of their exceptional ability to absorb oils.

Microfiber is constructed in a blend of 80/20 ratio of polyester/polyamideams. They are made from a warp knitted thread, composed of wedge-shaped polyester filaments with a core of nylon. The fiber's wedge shaped filaments follow surfaces, lift up dirt, and then trap the particles inside the fibers. The capillary effect between the filaments and nylon core creates a high absorbency, which in turn enables this cloth to clean and polish at the same time.

To clean a microfiber cloth, wash with warm soapy water and rinse well. The warm water opens up the fibers, allowing them to release the locked in dirt. Placing the cloths in a washing machine and then drying them in a dryer on low heat is also effective. No fabric softeners of any kind should be used as the chemicals clog up the microfibers, making them less effective. Bleach should also be avoided as it corrodes the fibers over time, making them less effective. Ironing is also potentially damaging.

Microfiber performance apparel has become a very popular alternative to cotton apparel for athletic wear, such as cycling jerseys, because the microfiber material wicks moisture away from the body, keeping the athlete cool and dry. Microfibers were also initiated for use in the military and for many federal agencies, such as in the so-called Future Force Warrior Program in the United States. This allows for more rapid drying of the soldier and less skin irritation due to moisture.

Microfiber materials, such as PrimaLoft are also used for thermal insulation as a replacement for down feather insulation in sleeping bags and outdoor equipment, due to its better retention of heat when damp or wet.

With microfiber basketballs already popular worldwide and in FIBA, the NBA proposed the use of a microfiber ball so players could handle the ball better. This comes about because microfiber has the ability to absorb water and oils, meaning that sweat from players touching the ball is better absorbed, making the ball less slippery.

Microfiber is also widely used by car detailers to handle such tasks as removing wax, quick detailing, cleaning interior, cleaning glass, as well as drying. Due to its fine fibers which leave no lint or dust, microfiber towels are a popular choice for avid car detailers and enthusiasts. Chamois leather is also used.

Note for Cyanobacteria
Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria. They are a significant component of the marine nitrogen cycle and an important primary producer in many areas of the ocean, but are also found on land.

Stromatolites of fossilized oxygen-producing cyanobacteria have been found from 2.8 billion years ago. The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the life forms on Earth and provoked an explosion of biodiversity. Chloroplasts in plants and eukaryotic algae have evolved from cyanobacteria.

Cyanobacteria are found in almost every conceivable habitat, from oceans to fresh water to bare rock to soil. Most are found in fresh water, while others are marine, occur in damp soil, or even temporarily moistened rocks in deserts. A few are endosymbionts in lichens, plants, various protists, or sponges and provide energy for the host. Some live in the fur of sloths, providing a form of camouflage while they are safe.

Cyanobacteria include unicellular and colonial species. Colonies may form filaments, sheets or even hollow balls. Some filamentous colonies show the ability to differentiate into several different cell types: vegetative cells, the normal, photosynthetic cells that are formed under favorable growing conditions; akinetes, the climate-resistant spores that may form when environmental conditions become harsh; and thick-walled heterocysts, which contain the enzyme nitrogenase, vital for nitrogen fixation. Heterocysts may also form under the appropriate environmental conditions (anoxic) wherever nitrogen is necessary. Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas, which cannot be used by plants, into ammonia (NH3), nitrites (NO2−) or nitrates (NO3−), which can be absorbed by plants and converted to protein and nucleic acids. The rice paddies of Asia, which produce about 75% of the world's rice, could not do so were it not for healthy populations of nitrogen-fixing cyanobacteria in the rice paddy fertilizer too.

Many cyanobacteria also form motile filaments, called hormogonia, that travel away from the main biomass to bud and form new colonies elsewhere. The cells in a hormogonium are often thinner than in the vegetative state, and the cells on either end of the motile chain may be tapered. In order to break away from the parent colony, a hormogonium often must tear apart a weaker cell in a filament, called a necridium.

Each individual cell of a cyanobacterium typically has a thick, gelatinous cell wall. They differ from other gram-negative bacteria in that the quorum sensing molecules autoinducer-2 and acyl-homoserine lactones are absent. They lack flagella, but hormogonia and some unicellular species may move about by gliding along surfaces. In water columns some cyanobacteria float by forming gas vesicles, like in archaea.

Note for Transmission Electron Microscopy
Transmission electron microscopy (TEM) is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through it. An image is formed from the electrons transmitted through the specimen, magnified and focused by an objective lens and appears on an imaging screen, a fluorescent screen in most TEMs, plus a monitor, or on a layer of photographic film, or to be detected by a sensor such as a CCD camera. The first practical transmission electron microscope was built by Albert Prebus and James Hillier at the University of Toronto in 1938 using concepts developed earlier by Max Knoll and Ernst Ruska.

Theoretically the maximum resolution that one can obtain with a light microscope has been limited by the wavelength of the photons that are being used to probe the sample and the numerical aperture of the system. Early twentieth century scientists theorized ways of getting around the limitations of the relatively large wavelength of visible light (wavelengths of 400–700 nanometers) by using electrons. Like all matter, electrons have both wave and particle properties (as theorized by Louis-Victor de Broglie), and their wave-like properties mean that a beam of electrons can be made to behave like a beam of electromagnetic radiation. Electrons are usually generated in an electron microscope by a process known as thermionic emission from a filament, usually tungsten, in the same manner as a light bulb, or by field emission. The electrons are then accelerated by an electric potential (measured in V, or volts) and focused by electrostatic and electromagnetic lenses onto the sample. The beam interacts variously with the sample due to differences in density or chemistry. The beam that is transmitted through the sample contains information about these differences, and this information in the beam of electrons is used to form an image of the sample.

Just as details of a light microscope sample can be enhanced by the use of stains, staining can be used to enhance differences in a sample for electron microscopy. Compounds of heavy metals such as osmium, lead or uranium can be used to selectively deposit heavy atoms in areas of the sample and to enhance structural detail by the dense nuclei of the heavy atoms scattering the electrons out of the optical path. The electrons that remain in the beam can be detected using a photographic film, or fluorescent screen among other technologies. So areas where electrons have been scattered in the sample can appear dark on the screen, or on a positive image due to this scattering.

The TEM is used heavily in both material science/metallurgy and the biological sciences. In both cases the specimens must be very thin and able to withstand the high vacuum present inside the instrument.

For biological specimens, the maximum specimen thickness is roughly 1 micrometre. To withstand the instrument vacuum, biological specimens are typically held at liquid nitrogen temperatures after embedding in vitreous ice, or fixated using a negative staining material such as uranyl acetate or by plastic embedding. Typical biological applications include tomographic reconstructions of small cells or thin sections of larger cells and 3-D reconstructions of individual molecules via Single Particle Reconstruction.

In material science/metallurgy the specimens tend to be naturally resistant to vacuum, but must be prepared as a thin foil, or etched so some portion of the specimen is thin enough for the beam to penetrate. Preparation techniques to obtain an electron transparent region include ion beam milling and wedge polishing. The focused ion beam (FIB) is a relatively new technique to prepare thin samples for TEM examination from larger specimens. Because the FIB can be used to micro-machine samples very precisely, it is possible to mill very thin membranes from a specific area of a sample, such as a semiconductor or metal. Materials that have dimensions small enough to be electron transparent, such as powders or nanotubes, can be quickly produced by the deposition of a dilute sample containing the specimen onto support grids. The suspension is normally a volatile solvent, such as ethanol, ensuring that the solvent rapidly evaporates allowing a sample that can be rapidly analysed.

Co-authors along with Griffith include Smaranda Willcox, research analyst, Lineberger Comprehensive Cancer Center; Dennis W. Powers, Ph.D., geology and geological engineering department, University of Mississippi; Roger Nelson, U.S. Department of Energy, Carlsbad, N.M.; and Bonnie Baxter, Ph.D., biology department, Westminster College, Salt Lake City, Utah.

The study was supported in part by grants from the National Institute of Environmental Health Sciences and the National Institute of General Medical Sciences.