Intracellular Accumulation of Uranium and Lead in Collembolan (Insect)

The midgut epithelium of Collembola contains cytoplasmic inclusions known to be important intracellular sites of mineral sequestration (1). The present study is focused on the role played by these inclusions in cases of heavy metal poisoning. Ultrastructural and X-ray microanalytical studies allowed us to find out different possible mechanisms involved in storage and excretion of these metals. Experiments have been made by rearing the Insects on diet impregnated with the heavy metal (1 % aqueous solutions of uranyl acetate and lead citrate). For each series 100 animals were tested. Animals alive after 2 months were fixed for electron microscopy with glutaraldehyde and osmium tetroxyde. Semi-thin sections were analysed with an electron microprobe analyser CAMECA MS 46 equipped with wavelength dispersive spectrometers (W.D.S.) at 15 KV ; beam current was 40 nA. X-ray microanalysis of thin unstained sections was performed on a “CAMEBAX” microanalyser equipped for transmission with W.D.S. at 50 KV and with a beam current of 100 nA. The use of R.E.T. crystal to detect uranium and lead avoids any misinterpretation (2).