THE ROLE OF LYSOSOMES IN THE SELECTIVE CONCENTRATION OF MINERAL ELEMENTS - A MICROANALYTICAL STUDY

The role of the lysosome during the intracellular concentration of div erse mineral elements has been evidenced by the electron probe X-ray m icroanalysis (EPMA). This highly sensitive technique allows an in situ chemical analysis of any chemical element with an atomic number great er than 11, present in ultra-thin tissue sections. Therefore, it has b een demonstrated by using this EPMA that 21 out of the 92 elements of the periodic table, once injected in a soluble form, were selectively concentrated within lysosomes of several types of mammalian cells. Amo ngst these 21 elements, 15 are concentrated and precipitated in an ins oluble form in association with phosphorus whereas the other 6 are pre cipitated in association with sulphur. Amongst the 15 elements which p recipitate with phosphorus in lysosomes, there are: 3 group IIIB eleme nts of the periodic system, (aluminium, gallium and indium); the rare- earth elements (cerium, gadolinium, lanthanum, thulium and samarium); 2 group IVA elements (hafnium and zirconium), two actinides (uranium a nd thorium) and elements such as chromium and niobium. The 6 elements which precipitate with sulphur comprise the 3 group VIII elements of t he classification (nickel, palladium, platinum) and the 3 group IB ele ments (copper, silver and gold). The mechanisms responsible for this s elective concentration involve enzymatic processes and predominantly a cid phosphatases for elements precipitating as phosphates and arylsulf atases for elements precipitating with sulphur.