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High Density Columnar Hexatic Liquid Crystalline DNA Mesophases - At the highest DNA concentrations formed both in vivo and in vitro, the long-chain molecule transcends into a liquid crystalline phase of high density resembling a smectic-like texture. This phase is two-dimensionally ordered and has been demonstrated through X-ray diffraction and electron microscopy to exist in a columnar hexatic liquid crystalline phase. The links below contain photomicrographs of this highly ordered phase of DNA.

High density liquid crystalline DNA phases have long range two-dimensional order, with the molecules arranged in planes at a defined angle to the preferred orientation direction of the long molecular axes. Focal conic and striated fan textures are observed for the highest DNA concentration mesophases in controlled drying experiments. Close examination of DNA liquid crystal specimens having a concentration exceeding 350 milligrams per milliliter (mg/ml) confirms that DNA forms a complex mesophase with molecular layering resembling that found in hexatic phases of small molecules.

This research was conducted in collaboration with Dr. Randolph L. Rill of the Department of Chemistry and Institute of Molecular Biophysics and Dr. David H. Van Winkle of the Center for Materials Research and Technology at the Florida State University.


High Density DNA "Single Crystal" - Grown from aqueous saline solution buffered with citrate at pH 7.3, this calf thymus DNA single crystal demonstrates birefringence and the beginning of a focal conic texture.

High Density Focal Conic Texture No. 1 - With a texture resembling pencil shavings, conical-shaped structures have a color pattern that shifts from blue to purple.

High Density Focal Conic Texture No. 2 - This pattern exhibits a Schlieren texture with a color transition from pinkish-purple to green. Miniature gas bubbles in the DNA specimen preparation account for "spots" seen on the focal conic textures.

High Density Focal Conic Texture No. 3 - After emerging from the cholesteric phase, batonnets form a confluent layer of focal conic textures in this photomicrograph.

High Density Focal Conic Texture No. 4 - A thickness gradient is readily apparent in this photomicrograph, which displays a rapid color transition in the liquid crystalline texture ranging from yellow to purple.

High Density Focal Conic Texture No. 5 - Spotted areas on the focal conic texture of this liquid crystalline DNA specimen indicate gas bubbles trapped within the mesophase. A narrow thickness gradient is present in the specimen, which is denoted by the gradual transition from purple to blue color shifts in the focal conic texture.

High Density Focal Conic Texture No. 6 - A uniform color tint throughout the photomicrograph presented above indicates a lack of thickness variation in the specimen. Schlieren patterns are also present on some of the conical textures.

High Density Focal Conic Texture No. 7 - A gradual transition from blue to green shades in the focal conic texture of this liquid crystalline DNA specimen are indicative of a progressive thickness gradient. Yellow and blue bands occur in some portions of the texture, which are evidence of a variation in the molecular organization of the mesophase.

High Density Focal Conic Texture No. 8 - A gradual transition from blue to purple shades in the focal conic texture of this liquid crystalline DNA specimen are indicative of a very shallow thickness gradient. Note the yellow spots with a red outline in some portions of the texture, which are evidence of gas bubbles in the specimen.

High Density Focal Conic Texture No. 9 - The shift in interference colors from yellow to orange seen from bottom to top in the photomicrograph presented in this section is indicative of a gradual thickness gradient. Many of the focal conic textures also display banding, which occurs as the DNA concentration approaches that seen in single crystals.

High Density Focal Conic Texture No. 10 - Three dark circles highlight the photomicrograph in this section, which illustrates a highly striated focal conic high density liquid crystalline DNA phase. The circles are actually gas bubbles that formed during preparation of the specimen and are devoid of DNA.

High Density Focal Conic Texture No. 11 - Schlieren patterns appear at the edges of the ragged focal conic texture exhibited by the high density liquid crystalline DNA sample presented in this section. This often occurs in populations of rod-like DNA molecules that have a very heterogeneous distribution of molecular weights (and lengths).

High Density Focal Conic Texture No. 12 - Beautiful blue focal conic textures appear highly striated in this high density liquid crystalline DNA sample.

High Density Focal Conic Texture No. 13 - The vast size difference in focal conic texture size exhibited by the DNA sample presented in this section indicates a variety of crystallization rates. The smaller textures in the top portion of the micrograph formed at a much faster rate than the larger texture at the bottom.

High Density Focal Conic Texture No. 14 - Color shifts from green to blue in the focal conic texture of this high density liquid crystalline DNA specimen indicate an increase in specimen thickness from the top (less thick) to the bottom (more thick) of the photomicrograph.

High Density Focal Conic Texture No. 15 - A rich velvet-like purple to blue texture is exhibited by this lightly striated high density liquid crystalline DNA specimen.

High Density Focal Conic Texture No. 16 - Higher order interference colors (pink and green) are displayed by the high density liquid crystalline DNA in the photomicrograph presented in this section. This indicates that the sample is much thicker than those that display lower order colors such as yellow, blue, and purple.

High Density Focal Conic Texture No. 17 - A transition from purple/yellow to blue colors is displayed by the focal conic texture of this liquid crystalline DNA specimen.

High Density Focal Conic Texture No. 18 - Thick striations in the focal conic textures displayed by the photomicrograph presented in this section are indicative of a very high DNA concentration. Note the spots that occur on the surface of the texture, which arise from gas bubbles trapped within the liquid crystalline specimen.

High Density Focal Conic Texture No. 19 - One of the most beautiful photomicrographs in our DNA collection, this specimen displays a color transition from yellow to purple in the focal conic texture. Heavy striations also indicate that the specimen is approaching the concentrations observed in single crystals.

High Density Focal Conic Texture No. 20 - Another beautiful photomicrograph, which displays a color transition from pink to green in the focal conic texture. Heavy striations also indicate that the specimen is approaching the concentrations observed in single crystals.

High Density Focal Conic Texture No. 21 - This heavily striated focal conic DNA texture has an interference color transition ranging from purple to orange. Color shifts of this type indicate a thickness gradient in the liquid crystalline preparation as it exists on the microscope slide.

High Density Focal Conic Texture No. 22 - This heavily striated focal conic DNA texture has an interference color transition ranging from purple to orange. Color shifts of this type indicate a thickness gradient in the liquid crystalline preparation as it exists on the microscope slide.

High Density Focal Conic Texture No. 23 - A purple striated focal conic texture forms a brush-like pattern riddled with spots arising from gas pockets within the specimen. The high degree of striation suggests that the DNA concentration is very high, approaching that observed in single crystals.

High Density Focal Conic Texture No. 24 - A color transition from turquoise to blue in this DNA specimen suggests a very narrow thickness gradient proceeding from left to right.

High Density Focal Conic Texture No. 25 - The photomicrograph presented above was captured at the edge of the coverslip during controlled drying liquid crystalline DNA experiments. Heavily striated focal conic textures indicate that the specimen is approaching the concentration seen in single DNA crystals.

High Density Focal Conic Texture No. 26 - A shift of color from green to blue in the focal conic texture of this specimen demonstrates a very slight thickness gradient. Spots on the fans occur because of small gas pockets trapped within the liquid crystalline phase.

High Density Focal Conic Texture No. 27 - Schlieren interference patterns are present on the edges of the focal conic fans in this liquid crystalline DNA specimen. The pink color and interference patterns indicate that the specimen is very thick.

High Density Focal Conic Texture No. 28 - The beautiful color transition in this specimen ranges from yellow to purple and covers a wide spectrum of intermediate colors.

High Density Focal Conic Texture No. 29 - With striations that are beginning to resemble chevron patterns, this highly concentrated DNA specimen is probably a single crystal.

High Density Focal Conic Texture No. 30 - Ribbon and brush-shaped fans in this specimen are highly striated. This is another example of a liquid crystalline DNA sample that is approaching the concentration observed in single crystals.

High Density Focal Conic Texture No. 31 - This beautiful liquid crystalline DNA photomicrograph illustrates a specimen having a color transition from pink to green. These are higher order interference colors indicative of a very thick specimen. Note the spots on the fans, which are caused by gas pockets within the specimen and striations that occur when high concentrations are attained.

High Density Focal Conic Texture No. 32 - Having a texture similar to that illustrated in specimen No. 19, this specimen was photographed near the edge of a coverslip. Note the spots on the fans, which are caused by gas pockets within the specimen and striations that occur when high concentrations are attained.

High Density Focal Conic Texture No. 33 - The pink and green interference colors exhibited by this high density liquid crystalline DNA focal conic texture indicate a very thick specimen. Pink spots on the fans, which are caused by gas pockets within the specimen, appear adjacent to striations that occur when high concentrations are attained.

Very High Density DNA Texture No. 1 - High molecular weight DNA usually has a large population of molecules having differing molecular lengths and does not undergo phase transitions in discrete steps. The image presented in this section is a high density DNA liquid crystalline phase prepared with heterogeneous calf thymus DNA of very high molecular weight.

Very High Density DNA Texture No. 2 - In controlled drying experiments with high molecular weight calf thymus DNA, the liquid crystalline phases reach a maximum concentration of about 650 milligrams per milliliter, approximately the same density as observed in prokaryotic and viral genomes.

Very High Density DNA Texture No. 3 - Another example of very high density calf thymus DNA that has reached the upper limit of liquid crystalline phase transitions, and has attained the highest concentration observed with DNA solutions.


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