M. G. Wolfersberger

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K+ transport by the epithelia of midgut, salivary glands, Malpighian tubules, sensory sensilla, possibly rectum, and other organs of certain insects appears to use a unique K+ ATPase. Ouabain inhibition of transport-related events has not been demonstrated in these epithelia. The K+ pump is unlike the Na-K;ump but resembles the H;ump of phosphorylating(More)
The tissue used in this study was the midgut of the tobacco hornworm larva, Manduca sexta. The midgut epithelium is a single layer of cells resting on a thin basal lamina and underlying discontinuous muscle layer. The epithelial cells are of two main types, goblet and columnar cells, joined together by the septate junctions characteristic of insect(More)
After incubation at pH 10 or higher, Bacillus thuringiensis spores and endotoxin, at concentrations above 0.1 IU/ml, affected transport parameters in the isolated midgut of Manduca sexta larvae. (Toxic activity was lost during roughly 1 week at pH 11.) About 60% of the short-circuit current was inhibited, and the remainder was reversibly inhibited by(More)
Using the rapid filtration technique, cation gradient driven leucine, alanine and phenylalanine uptake by brush-border membrane vesicles (BBMV) from the highly studied model insect, Manduca sexta, is characterized at the physiological pH of 10. The vesicles are sealed and nonspecific binding is small. Almost identical initial time courses of leucine uptake(More)
Purified goblet cell apical membranes from Manduca sexta larval midgut exhibit a specific ATPase activity approx. 20-fold higher than that in the 100 000 X g pellet of a midgut homogenate. The already substantial ATPase activity in this plasma membrane segment is doubled in the presence of 20-50 mM KCl. At ATP concentrations ranging from 0.1 to 3.0 mM, the(More)
Uptake of tritiated leucine, alanine, and phenylalanine was measured at the physiological pH of 10 by rapid filtration in brush-border membrane vesicles from the midgut of the larval tobacco hornworm, Manduca sexta. A 20-fold excess of unlabeled leucine, isoleucine, methionine, valine, alanine, lysine, histidine, phenylalanine, and glutamine inhibited(More)
Most insect cell membranes seem to contain uniporters that facilitate the diffusion of amino acids into and out of the cells. In addition to these passive diffusion systems, all but one of the insect tissues studied to date seem to contain at least one amino acid-cation symport system that allows their cells to accumulate certain amino acids from the(More)
Theδ-endotoxin fromBacillus thuringiensis subspecieskurstaki strain HD1-9 is almost 400 times more potent than theδ-endotoxin from strain HD-73 as a gypsy moth larvicide. The twoδ-endotoxins compete for a high-affinity binding site on the brush border membrane of larval gypsy moth midguts. The affinity for theδ-endotoxin from strain HD-73 is much greater(More)
Brush border membrane vesicles were prepared from both fresh and frozen midguts of Lymantria dispar larvae by Mg/EGTA precipitation and differential centrifugation. The vesicles were enriched 10 to 13-fold, relative to the homogenate, in aminopeptidase and gamma-glutamyltransferase activity. No significant difference was found in enzyme enrichment of(More)