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Journals and Conferences
Apical and basal membrane fractions from Locusta Malpighian tubules were prepared and were characterized by marker enzyme analysis. The apical membranes contained an azide- and orthovanadate-insensitive ATPase activity that was inhibited by bafilomycin A1 (IC50 = 0.44 nM) and NEM (IC50 = 2.15 microM), and thus was characterized as putative V-type ATPase.… (More)
Both fluid secretion and transepithelial potential were stimulated by cAMP. Fluid secretion was unaffected by 5-HT over the concentration range 10−8–10−4 M. The presence of ouabain in the bathing medium effected a decrease in transepithelial potential.
Intracellular distributions of Na, K, Mg, Ca, Cl, P, and S were determined in type 1 Malpighian tubule cells of Locusta using X-ray microanalysis. K showed a gradient of increasing concentration from basal to apical surfaces. No other element showed this distribution. Na was below the detection limit. Three types of dark body were present in cytoplasm; one… (More)
X-ray microanalysis was used to study elemental distribution in Malpighian tubule cells of Locusta migratoria and how these are affected by the replacement of bathing medium K+ with Rb+ and by inclusion of the transport inhibitors ouabain and n-ethyl maleimide (NEM) in standard (K+-containing) and Rb+-Ringer (K+-free) solutions. Incubation of tubules in… (More)
Carbohydrase activity has been demonstrated in homogenates of the alimentary tracts of late instar larvae ofC. maculatus:β-D galactosidase, α-D glucosidase and N-acetylβ-D glucosaminidase activities were comparable and significantly greater than α-D galactosidase,β-D glucosidase and α-D mannosidase. The effects of pH and substrate concentration are… (More)
Die Präsenz einer charakteristischen Na+−K+-aktivierbaren ATPase (E.C. 18.104.22.168) wurde erstmals in einer mikrosomalen Fraktion des Enddarmes und der malpighischen Gefässe bei der WüstenschreckeScistocerca gregaria und der LaubheuschreckeJamaicana flava nachgewiesen.
Carbohydrase activity has been demonstrated in homogenates of the alimentary tract ofC. maculatus: β-D galactosidase > α-D glucosidase > α-D galactosidase > β-D glucosidase activity. The effects of pH, temperature and substrate concentration on β-D galactosidase, α-D glucosidase and α-D galactosidase activities are described.
Temperature markedly affected the ouabain-sensitivity of both the Na+−K+-activated ATPase activity and the secretion of fluid by the Malpighian tubules ofLocusta. Varying the K+ concentration in the bathing medium did not affect the ouabain-sensitivity of the fluid secretory process.
Both Mg2+-ATPase and HCO 3 − -stimulated ATPase activity were inhibited by sodium azide and to a lesser extent ethacrynic acid and amiloride. 1 mM DNP stimulated Mg2+-ATPase activity by 22% and HCO 3 − -stimulated ATPase activity by 7%.