Hydrolysis of beet pulp polysaccharides by extracts of solid-state cultures of Pencicillium capsulatum

Extracts of solid-state cultures of Penicillium capsulatum grown on beet pulp exhibit cellulolytic, hemicellulolytic, and pectinolytic activities. Such extracts catalyzed extensive solubilization of untreated beet pulp. The effects of pH, temperature, and endproducts on the saccharification process were investigated.     

Quantitation of particles in the freeze-fractured nuclear membrane after renal ischemia.

Changes in the number and sizes of membrane-associated particles have been quantitated in the protoplasmic (P) and exoplasmic (E) fracture faces of the outer membrane of nuclei isolated from the inner cortex following renal ischemia and reflow in the rat. No changes were observed in the inner nuclear membrane. After 20-min ischemia, the number of particles in both fracture faces decreased. With reflow, the total number of particles decreased after both 20- and 60-min ischemia. The partition coefficient (Kp = CPF/CEF) increased from 10 to 11 and 17 at 20- and 60-min ischemia then fell below control values to a Kp of 7 after 120 min. After reflow, Kp steadily decreased except after 20-min ischemia followed by 240-min reflow when Kp began to rise. The sizes of particles were predominantly 60 A in the P face of control outer membranes but became larger after ischemia. After 20- and 60-min ischemia with reflow, the size distribution became more normal. The shifts in particle numbers and sizes seem to indicate modifications within the membrane resulting from ischemia.     

cDNA cloning and expression of aTalaromyces emersonii amylase encoding genetic determinant inEscherichia coli

Summary Intact mRNA has been isolated from the thermophilic fungusTalaromyces emersonii following growth on starch containing media. This has been used as template to synthesise cDNA. The cDNA was cloned into theEscherichia coli expression vector system, pUC18 and this was used to transformE. coli. Transformed colonies were screened for production of amylase activity and a number of positive recombinants were detected. One of those was found to contain a plasmid named pMH1, which harboured a 1.2 kb insert. Sub-cloning experiments verified that the amylase phenotype was encoded for by this fragment. The fragment was characterised using restriction enzyme cleavage site analysis. The origin of the insert was verified using both Northem and Southem blotting hybridisation analysis ofT. emersonii RNA and DNA respectively.     

Growing Pollen Tubes Possess a Constitutive Alkaline Band in the Clear Zone and a Growth-dependent Acidic Tip

Using both the proton selective vibrating electrode to probe the extracellular currents and ratiometric wide-field fluorescence microscopy with the indicator 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF)-dextran to image the intracellular pH, we have examined the distribution and activity of protons (H⁺) associated with pollen tube growth. The intracellular images reveal that lily pollen tubes possess a constitutive alkaline band at the base of the clear zone and an acidic domain at the extreme apex. The extracellular observations, in close agreement, show a proton influx at the extreme apex of the pollen tube and an efflux in the region that corresponds to the position of the alkaline band. The ability to detect the intracellular pH gradient is strongly dependent on the concentration of exogenous buffers in the cytoplasm. Thus, even the indicator dye, if introduced at levels estimated to be of 1.0 μM or greater, will dissipate the gradient, possibly through shuttle buffering. The apical acidic domain correlates closely with the process of growth, and thus may play a direct role, possibly in facilitating vesicle movement and exocytosis. The alkaline band correlates with the position of the reverse fountain streaming at the base of the clear zone, and may participate in the regulation of actin filament formation through the modulation of pH-sensitive actin binding proteins. These studies not only demonstrate that proton gradients exist, but that they may be intimately associated with polarized pollen tube growth.     

Tridimensional ultrastructure of freeze-fractured rat kidney cortex (studied in stereo)

The tridimensional ultrastructure of the inner cortex of rat kidney has been studied by observing freeze-fractured tissue in stereo. The complex structure of the tubules, fenestrated capillaries and glomeruli is more readily observed through the irregular fracturing of the tissue that occurs in this technique. The ultrastructure of the brush border and interdigitating membranes of the proximal tubules, the structure of the fenestrated endothelial membranes of the capillaries and the ribbonlike appearance of the filtration space between the foot processes of the glomeruli were especially well depicted in stereo images of freeze-fractured renal tissue.     

Cyclic 3',5'-adenosine monophosphate modulates vascular endothelial cell migration in vitro

Using a modified Boyden chamber assay, we have examined the effect of cyclic nucleotides on bovine aortic endothelial cell migration in vitro. Dibutyrl cyclic 3',5'-adenosine monophosphate (5 mM) inhibited endothelial cell random migration by 67% and inhibited fibronectin-induced chemotaxis by 75%. Agents which significantly stimulated adenylate cyclase activity in endothelial cell membranes were also effective inhibitors of endothelial cell migration. Timolol blocked both the isoproterenol-induced stimulation of adenylate cyclase and the ability of isoproterenol to inhibit endothelial cell migration. Caffeine and isoproterenol together had a greater inhibitory effect on endothelial cell motility than either alone. These data suggest that cAMP may modulate vascular endothelial cell migration in an inhibitory fashion.