Linkage analysis and the inheritance of arches in a Habbanite isolate.

A pedigree and linkage analysis was performed on a corrected version of the Habbanite pedigree 2 of Slatis et al. [1]. The trait "arch on any digit" was examined for major gene inheritance and possible linkage to several blood and serum group markers. The results confirm the proposed dominant major gene inheritance of this trait with almost complete penetrance. In addition, the analysis suggests linkage with the haptoglobin locus with evidence against linkage with Pl and Rhesus. These results are of particular interest in view of recently reported dermatoglyphic associations with haptoglobin.     

Sublethal stress in Escherichia coli: a function of salinity.

Sublethal stress in Escherichia coli was detected in various test media after exposure (in vitro) to seawater of various salinites. Stress was measured with an electrochemical detection technique and a beta-galactosidase assay. Test media included EC medium, medium A-1, and tryptic soy broth modified to contain lactose for beta-galactosidase assay experiments. Stress was defined as the difference between a predicted electrochemical response time calculated for unstarved cells from a standard curve and the observed electrochemical response time for cells starved in seawater. The higher the salinity, the greater the stress for all test media examined. Stress was most pronounced in EC and was attributed primarily to initial die-off of starved cells exposed to the test medium at the elevated temperature of 44.5 degrees C. Lag time and growth rates in test media were not significantly affected by salinity. beta-Galactosidase specific activity, assayed in starved cells after transfer to an induction medium at 44.5 degrees C for 150 min, was inversely related to the salinity of the starved cell suspension. The consequences of these observations with respect to coliform enumeration methods are discussed.     

Metal-free housing units for trace element studies in rats

Metal-free housing units fabricated from clear plastic and polystyrene egg crate panels were used to house rats for studies involving trace elements. The cages did not require bedding, were well ventilated and fitted into commercially available cage racks. Modifications of the basic design were made to provide both maternity and metabolism cages.     

Labeling of the Plasma Membrane of Pea Cells by a Surface-localized Glucan Synthetase

When radioactive UDP-glucose is supplied to 1-millimeter-thick slices of pea (Pisum sativum) stem tissue, radioactive glucose becomes incorporated into membrane-bound polysaccharides. Evidence is given that this incorporation does not result from breakdown of UDP-glucose and utilization of the resultant free glucose, and that the incorporation most likely takes place at the cell surface, leading to a specific labeling of the plasma membrane. The properties of the plasma membrane that are indicated by this method of recognition, including the association of K⁺-stimulated ATPase activity with the plasma membrane, resemble properties inferred using other approaches. The membrane-associated polysaccharide product formed from UDP-glucose is largely 1,3-linked glucan, presumably callose, and does not behave as a precursor of cell wall polymers. No substantial amount of cellulose is formed from UDP-glucose in this procedure, even though these cells incorporate free glucose rapidly into cellulose. This synthetase system that uses external UDP-glucose may serve for formation of wound callose.     

Complementary variational principles for the steady-state finite cable model of nerve membranes

Maximum and minimum principles for the steady-state finite cable model of nerve membranes are derived from the canonical theory of complementary variational principles. An accurate variational solution is obtained in an illustrative calculation.     

Immunocytochemical visualization of coated pits and vesicles in human fibroblasts: relation to low density lipoprotein receptor distribution.

The coated pit-coated vesicle system has a key role in the uptake of plasma low density lipoprotein (LDL) and other receptor-bound proteins in human fibroblasts. To study the distribution of coated pits and coated vesicles in fibroblasts by immunochemical techniques at both the light and electron microscopic levels, we immunized rabbits with coat protein extracted from bovine brain-coated vesicles. The resulting anti-coat protein antibody was directed predominantly against clathrin, the 180,ooo dalton protein that constitutes the major component of coat protein. By indirect immunoperoxidase electron microscopy, the anti-coat protein antibody was observed to bind specifically to coated pits on the surface of human fibroblasts and to coated vesicles within the cell. Indirect immunofluorescence and immunoperoxidase staining techniques at the light microscopic level revealed that the coat protein was distributed in fibroblasts in two distinctive patterns: as discrete foci on or near the cell surface that were linearly aligned in association with phase-dense cellular fibers (first pattern), and as intracellular foci that were randomly arranged around the cell nucleus (second pattern). The distribution of coat protein in fibroblasts was compared with the distribution of ferritin-labeled LDL, which was studied with the use of similar electron microscopic and immunofluorescence techniques. As previously reported, electron microscopic studies revealed that the LDL-ferritin binding sites at 4 degrees C were clustered in coated pits. By immunofluorescence microscopy, the LDL-ferritin that was bound to receptors within coated pits was shown to be arranged linearly over the cell surface in a pattern that was similar to the linear arrangement of coat protein (first pattern). Considered together, the current data indicate that coated pits in human fibroblasts contain a protein analogous to clathrin, and that those coated pits which contain receptors for LDL are located over intracellular fibers most likely corresponding to stress fibers. These observationa may have relevance to the mechanisms by which the coated pit-coated vesicle system efficiently delivers recptor-bound ligands to lysosomes.