Copper uptake by free and immobilized cyanobacterium

Abstract Copper uptake in free and immobilized cells of the cyanobacterium Nostoc calcicola has been examined. The immobilized cells invariably maintained a higher profile of Cu intake rate (12.7 nmol mg⁻¹ protein min⁻¹) over the free cells (6.0 nmol mg⁻¹ protein min⁻¹). The total Cu uptake in immobilized cells was almost two and a half-times more than their free cell counterpart under identical experimental conditions. Also, the immobilized cells showed a stronger positive correlation between Cu adsorption and uptake. The results have been discussed in terms of improved metabolic efficiency of immobilized cells.     

The fate of the fusarium mycotoxin zearalenone in maize cell suspension cultures

The fusarium mycotoxin zearalenone was transformed in cell suspension cultures of Zea mays giving α- and β-zearalenol and the β-D-glu cos ides of zearalenone and α- and β-zearalenol. The structure of zearalenone-4-β-D-glucopyranoside was determined by liquid — chromatography-mass spectrometry and specific hydrolysis with β-glucosidase. α- and β-zearalenol and their glucosides were identified by co chromatography using tic and HPLC and glucosidase — treatment Up to 50% of the mycotoxin added was bound to a non extractable or “bound” residue fraction. After treating this residue by a sequential cell wall fractionation procedure, zearalenone was found to be bound mainly to starch, hemicellulose, and lignin fractions.     

Purification and characterization of the inositol 1,4,5-trisphosphate receptor protein from rat vas deferens

Among rat peripheral tissues examined, Ins(1,4,5)P(3) receptor binding is highest in the vas deferens, with levels about 25% of those of the cerebellum. We have purified the InsP(3) receptor binding protein from rat vas deferens membranes 600-fold. The purified protein displays a single 260 kDa band on SDS/PAGE, and the native protein has an apparent molecular mass of 1000 kDa, the same as in cerebellum. The inositol phosphate specificity, pH-dependence and influence of various reagents are the same for purified vas deferens and cerebellar receptors. Whereas particulate InsP(3) binding in cerebellum is potently inhibited by Ca(2+), particulate and purified vas deferens receptor binding of InsP(3) is not influenced by Ca(2+). Vas deferens appears to lack calmedin activity, but the InsP(3) receptor is sensitive to Ca(2+) inhibition conferred by brain calmedin. The vas deferens may prove to be a valuable tissue for characterizing functional aspects of InsP(3) receptors.     

Rat brain endoplasmic reticulum calcium pools are anatomically and functionally segregated.

Autoradiographic imaging can localize 45Ca2+ selectively accumulated via the Ca2+, Mg2(+)-ATPase into endoplasmic reticulum stores in rat brain slices. 45Ca2+ accumulation is markedly stimulated by oxalate and displays a heterogeneous distribution which resembles the mRNA distribution for a sarcoendoplasmic reticulum Ca2+, Mg2(+)-ATPase. Inositol 1,4,5-triphosphate [I(1,4,5)P3] inhibits 45Ca2+ accumulation selectively into regions corresponding to those enriched in I(1,4,5)P3 receptor-binding sites and in Ca2+, -Mg2(+)-ATPase mRNA. Thus rat brain endoplasmic reticulum calcium stores are anatomically and functionally differentiated.