Imaging Sims Studies Of Brdu-Labelled Human Metaphase Chromosomes

Riccardo Levi-Setti, Ph.D.
Director, Enrico Fermi Institute
University of Chicago
Chicago, Illinois

Wednesday, November 29, 1995

Dr. Levi-Setti et al. have shown that isotope-labeled nudeosides in human metaphase chromosomes can be detected and mapped by imaging secondary ion mass spectrometry (SIMS) using the University of Chicago high resolution scanning ion microprobe (UC SIM). The high transmission of the new spectrometer improves the SIMS analytical sensitivity of the microprobe better than fifty-fold, overcoming most of the previous imaging limitations resulting from low count statistics. Due to the low current of their GA + probe (here -6 pA), it is feasible to explore the inŽdepth chromosomal composition by sequential mappings (SIMS tomography). With a probe size of 35 nm, the analytical image resolution is consistently better than 100 nm taking into account statistical considerations.

Dr. Levi-Setti is concurrently working on field and laboratory work in invertebrate paleontology (trilobites). His profession in physics spans over 45 years.