Willow (Salix babylonica L.) is representative of a large group of plants that have extensive plasmodesmatal connections between minor vein phloem and adjoining cells. Because plasmodesmata provide a diffusion pathway for small molecules, it is unclear how sucrose could be loaded from the mesophyll into the phloem against a concentration gradient. In the studies reported here, the minor vein ph...

We describe a simple and low cost nonlinear gradient former. The apparatus is derived from a 20 ml syringe and was used to build up sucrose gradients (1) for the separation of DNA fragments needed for the construction of a cosmid library. The setup is given in Figure 1. The lower chamber underneath the plunger is the mixing chamber containing a given volume of the lower concentrated solution, t...

Assimilates enter developing wheat grains via a strand of phloem extending along the crease region of the grain. After phloem unloading, they move several hundred micrometers before being released into the endosperm cavity, from which they are absorbed by the developing endosperm. Extraphloem assimilate pools in the maternal tissue of the crease, therefore, play a central role in postphloem tra...

The regulation of gap junctional permeability by phosphorylation was examined in a model system in which connexin 43 (Cx43) gap junction hemichannels were reconstituted in lipid vesicles. Cx43 was immunoaffinity-purified from rat brain, and Cx43 channels were reconstituted into unilamellar phospholipid liposomes. The activities of the reconstituted channels were measured by monitoring liposome ...

1. Methods of disrupting Krebs II mouse ascites-tumour cells have been studied. After washing the cells free of ions with sucrose solutions, rapid disruption was obtained in sucrose by use of an Ultra-Turrax disintegrator or a Dounce homogenizer. 2. Disruption of cells after osmotic shock led to the loss of proteins, especially cytochrome c, from the mitochondria. Such losses did not occur when...

Contrary to electrofocusing in sucrose gradients free [3H]oestradiol-17/l did not electrofocus and did not migrate significantly from the point of application. This could present difficulties in the interpretation and resolution of components if the sample is placed on the gel at a point close to the isoelectric points of the components of interest. By placing the sample 10-15mm from the cathod...