Bottle Stoppers Research Articles

14] In Vitro iodination of nucleic acids

Publisher Summary This chapter discusses in vitro iodination of nucleic acids. Nucleic acids can be labeled, with a radioactive isotope in vitro, by heating them in a mixture containing radioactive iodine and thallic trichloride (TlCl3). The reaction is rapid and simple, and results in the formation of a stable covalent bond between the radioactive iodine atom and carbon atom of cytosine in the nucleic acid. The biological properties of the nucleic acid are not significantly affected by this procedure. During iodination of nucleic acids, some of the radioactive iodine isotope becomes volatile. Radioactive contamination of the laboratory can be minimized by placing a gas-tight seal on the reaction container, by adding 125I to the mixture through the seal by means of a hypodermic syringe, and by withdrawing air from the sealed container by means of a syringe so that the inner pressure remains less than atmospheric even when the container is heated to 70°. Serum bottle stoppers, 13 × 20 mm, are suitable for 12 × 125 mm Pyrex glass test tubes and Burrell silicone seals are suitable for 4 × 50 mm Pyrex tubes.

Square acrylamide gel columns and a novel gel slicer

The resolution of protein mixtures obtainable by the use of the disc electrophoresis technique (1, 2) often exceeds the recording capabilities of photometric densitometers (3). Accurate recording of the stained protein bands in the cylindrical gels is impeded by spherical aberration (4). Multiple longitudinal gel slices (5) for radioautography, enzyme assays, or staining comparisons must of necessity be varying widths when cylindrical gels are used. Some of these difficulties can be overcome by making the gel in square tubing, as described in this report. The substitution of square gels provides the advantage of a flat optical plane which simplifies both photographic and scanning procedures (6). The flat surface also allows uniform longitudinal gel slices to be cut. In addition, we are describing a simple device that yields 1 mm uniform sequential slices normal to the longitudinal axis of the gel column, and the destaining of gel columns in devices designed for destaining gel slabs (7). An apparatus similar to that described by Davis (2) was used to perform the electrophoresis. Glass tubes 6 mm square and 112 mm long were used as gel f0rms.l The square tubes were heated at one end and molded till the cross section of the tube was round for a distance of 7 mm from one end in order to provide a tight seal when inserted into the round hole in the upper buffer chamber grommets. The square ends were plugged with sleeved small serum bottle stoppers. The gel columns were then prepared by the normal procedure (2). Round and “square” gels were prepared and run at the same time under the same conditions. Comparable resolution (Fig. 1) was obtained, but the “square” gels photograph with sharper edges. The gels can be removed after electrophoresis by rimming with a water jet from a 2 in. #26 hypodermic needle connected to a wash bottle. Gel removal is facilitated by using tubes coated with a 10%

Disc electrophoresis: an improved technique.

Abstract The disc electrophoretic technique of Ornstein and Davis has been modified to eliminate the need of rubber serum bottle stoppers and to facilitate the use of fluid, unpolymerized, samples. The basis of the new technique is a specially designed apparatus which holds and seals the ends of the tubes during filling and polymerization.

New Procedures of Bryophyte Culture Which Permit Alteration of the Culture Medium during the Life Cycle

New Procedures of Bryophyte Culture Which Permit Alteration of the Culture Medium during the Life Cycle

An extractor for "frozen" bottle stoppers

An extractor for "frozen" bottle stoppers