9317959 Levi-Setti The radical upgrade of the mass discrimination capability and secondary ion detection sensitivity of the University of Chicago high resolution Scanning Ion Microprobe (UC SIM) is near completion. This upgrade has entailed the interfacing of the microprobe with a high performance magnetic sector mass spectrometer, while retaining the superior performance of the primary beam ion optics and allowing alternate use of the previous RF quadrupole mass filter. Although the principal hardware and electronic components needed for this complex upgrade have been constructed and are now operational, a most critical phase of new instrument development is still to be completed. The construction of several ancillary devices, originally deemed of secondary priority within the previous budgetary constraints, is now regarded as a worthwhile and necessary complement to the already successful instrumental upgrade. Most of all, the complexity of the joint operation of the microprobe with the highly sophisticated Finnigan MAT chemical mass spectrometer requires extensive optimization and performance evaluation, together with training of students and staff. As demonstrated in previous phases of our instrument development, the concurrent pursuit of fundamental biological studies has remained consistently one of the highest priorities of our program. In collaboration with established biologists from several academic institutions, systematic investigations and exploratory applications of high resolution secondary ion imaging have already yielded unique results and have created a very productive interface between the physical and the biological sciences. At a much improved level of performance, several pilot studies which already show promise will be actively pursued: (a) Direct mapping of the distribution of isotope labelled nucleosides in human chromosomes and evaluation of the nucleotide content of fragile sites. (b) Direct mapping of the distribution of isotope labelled nucleosides in Drosophila melanogaster metaphase and polytene chromosomes. (c) Identification of the pathways of bone resorption initiated by osteoclasts. Determination of the calcium to phosphorus radio in bone formation and resorption, This will entail experiments with Ca isotopes as tracers, and the detection and measurement of phosphorus. u ~ s t s % ) ~ + * , . g L c X 3 d h Z % i ? - 9317959 Levi-Setti The radical upgrade of the mass discrimination capability and secondary ion detection sensitivity of t u ) u O ! ! ! ! F K K ; CG Times Symbol & Arial 1 Courier 0 MS LineDraw E E h : % : % F = = abstract Deseree King, BIR Deseree King, BIR
