An attempt was made to evaluate Münch's hypothesis of osmotically generated pressure flow in soybean (Glycine max L.) sieve tubes from velocity measurements and calculations of pressure potentials and sieve tube resistances. Pressure potential was estimated from values for water potentials and osmotic potential. Leaf water potential measurements were made by isopiestic thermocouple psychrometry...

K-region oxide, 3MG-il ,12-axide, to induce single-strand breakage in DNA of human fetal and neonatal skin cells; we have also examined DNA repair in the latter system. Toward this end, we have utilized the alkaline sucrose gradient technique as the tool far demonstrating single-strand breaks. The results of this study indicate that in the pres ence of the K-region oxide the DNA of these human ...

* Contribution Number 369 from the McCollum-Pratt Institute and The Department of Biology, The Johns Hopkins University, Baltimore, Maryland. t The following abbreviations are used: DPN, DPNH, and TPN for the oxidized and reduced diand triphosphopyridine nucleotides; RNA for ribonucleic acid; ADP and ATP for the adenosine diand triphosphates; Pi for inorganic phosphate; G-6-P for glucose-6-phos...

The efficiency with which proteins are produced from mRNA molecules can vary widely across transcripts, cell types, and cellular states. Methods that accurately assay the translational efficiency of mRNAs are critical to gaining a mechanistic understanding of post-transcriptional gene regulation. One way to measure translational efficiency is to determine the number of ribosomes associated with...

Tonoplasts were isolated in a high purity from etiolated young seedlings of Vigna radiata L. (mung bean) utilizing a sucrose density gradient system. The excised hypocotyls were homogenized in a sorbitol-buffer system and the 3,600 to 156,000g pellets obtained after the differential centrifugations were suspended in a sorbitol medium and loaded on a linear sucrose density gradient. After centri...

A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg(++) and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. Th...

1. Comparison with other density gradient media Compared to CsCl and sucrose there are procedural advantages to the use of OptiPrepTM: ♦ OptiPrepTM is a sterile solution of 60% (w/v) iodixanol; it is simply diluted with saline to prepare sterile gradient solutions. It is the only gradient medium manufactured under strict FDA and EU cGMP compliance. ♦ CsCl and sucrose are both toxic to cells. ♦ ...

Trees are generally assumed to be symplastic phloem loaders. A typical feature for most wooden species is an open minor vein structure with symplastic connections between mesophyll cells and phloem cells, which allow sucrose to move cell-to-cell through the plasmodesmata into the phloem. Fraxinus excelsior (Oleaceae) also translocates raffinose family oligosaccharides in addition to sucrose. Su...

Trees are generally assumed to be symplastic phloem loaders. A typical feature for most wooden species is an open minor vein structure with symplastic connections between mesophyll cells and phloem cells, which allow sucrose to move cell-to-cell through the plasmodesmata into the phloem. Fraxinus excelsior (Oleaceae) also translocates raffinose family oligosaccharides in addition to sucrose. Su...

Sucrose gradient sedimentation analysis of rotavirus SA11-infected Ma104 cells revealed the presence of oligomers of VP7, the structural glycoprotein, and NS28, the nonstructural glycoprotein. Cross-linking the proteins, either before or after sucrose gradient centrifugation, stabilizes oligomers, which can be analyzed by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SD...