Calcium-cadmium competition in ovarian vitellogenic follicles of Galleria mellonella as revealed by X-ray microanalysis.

Dissected ovarioles of Galleria mellonella were exposed for 60 min to cadmium, supplied to insect culture medium in amount equalling that of calcium therein. The sections of ovarioles treated with a fixative precipitating both elements and embedded in epon were examined using energy-dispersive X-ray microanalysis system. Analysis of the digital maps obtained suggests a free inflow of Ca2+ and Cd2+, in approximately equal amounts.

The role of vacuolar digestive system in preventing cadmium poisoning in Acanthamoeba castellanii.

Constituents showing cadmium affinity were found in digestive residues of the vacuolar digestive system in Acanthamoeba. Cadmium was detected by means of X-ray analysis in complexes appearing both in residues included within the digestive vacuoles and in those egested outside the cell. The digestive vacuolar system in Acanthamoeba castellanii is characterized by a particularly high turnover rate (4).

Replacement of calcium by cadmium ions from Ca-affinity sites localized in different cytoplasmic compartments of Acanthamoeba cells.

In Acanthamoeba cells both Ca and Cd may be precipitated in different cytoplasmic compartments forming electron-opaque deposits, as shown in cells treated with glutaraldehyde supplied with either Ca or Cd respectively. It was found by semiquantitative X-ray microanalysis that the transfer of cells containing Ca-deposits to glutaraldehyde supplied with Cd causes a considerable replacement of Ca by Cd: in deposits formed at cell membrane, in cytoplasm, and in mitochondria the total weight percentage of Cd amounted to over 90, only in deposits formed in vacuoles the value was about 80. The replacement was not prevented by the presence of Ca in the transfer medium.

Ultracytochemical localization and microprobe quantitation of calcium stores in the insect oocyte.

Detection of calcium in the follicles of Galleria mellonella (Lepidoptera) was performed using two cytochemical methods. Calcium precipitation was obtained either with ammonium oxalate (AO) or with N,N-naphtaloylhydroxylamine (NHA). In both cases the X-ray "on line" analysis monitored the presence of calcium in the oocytes, which was correlated with the accumulation of yolk spheres.

Displacement of cell-surface associated calcium inhibits phagocytosis and Ca-ATPase activity in amoeba.

Displacement of calcium from the cell surface region was observed in cells treated with either chlorpromazine or reserpine with chlorotetracycline being used as a calcium-fluorescent probe. The drugs also significantly inhibit the intensity of phagocytosis and Ca-ATPase activity. The possible role of Ca associated with the cell surface region in regulation of both phagocytosis and Ca-ATPase was discussed.