A b s t r a c t s 18 7

TOOLS FOR MOLECUI.AR CYTOGENETICS

R. Marzella;, T. StorlazziL A. Ricco;, A. Lonoce ~, L. ViggianoL N. Archid iaconoL M. Rocchi ~

qstituto di Genet ica, UniversitO cti Bari, Italy Fax +39-80-544.3386; e-mail m.rocchi@area.ba.cnr.it 2Consorzio C.A.R.S.O., Bari, Italy

The fluorescence in situ hybridization technique (FISH), developed in recent years, represents a major step in cytogenetics. Alphoid centromeric probes and whole-chromosome painting libraries (WCPL), in particular, have proved to be of great help in characterizing chromosome rearrangements, both in normal and in tumor cells, that were difficult to investigate by conventional banding techniques.

Our laboratory is involved in a project aiming at the generation of molecular cytogenetic tools for the very fine characterization of cytogenetic rearrangements. In detail, we are producing:

a) 23 radiation hybrid panels, one for each human chromosome, each hybrid retaining a single fragment of small/medium size (from few Mb to entire short or long arms). They can be used as source material to generate (via Alu-PCR) subchromosomal painting libraries (SCPL), that is, libraries that paint not an entire human chromosome, but a specific region of a chro- mosome. Their molecular characterization will be refined using a large sets of specific STSs.

b) a panel of YAC probes (from CEPH) characterized by FISH, homogeneously spaced along the genome (about 1000 in all, one every 3Mb approximately) as additional tool for cytogenetic studies.

Panels of SCPLs are available for chromosomes 2, 5, 10 and X. Panels of YAC are available for chromosomes 5, 10, and X. Both sets of probes are free available to the scientific communicty. Their use in the cytogenetic analysis of tumor cells will be illu:ttrated.

ANALYSIS OF PRIMARY AND RECURRENT MENINGIOMA BY COMBINED CYTOGENETIC TECHNIQUES

SE. Dos Santos(1), B. Hemery(1), B. Perissel(1), M. Giollant(1), B. Irthum(2), P. Malet*(1)

I Laboratoire de Cytog6n6tique M6dicale, CHU de Clermont- Ferrand, France; 2 HOpital Fontmaure, CHU, Clermont-Ferrand, France

Meningiomas are the most common human intracranial neoplasms. They are classified as benign tumors of W.H.O grade I-II. However, a histologically variable subset of these tumors tends to invasive growth or to recurrence (1).

Monosomy of chromosome 22 in meningioma was the first consistent cytogenetic anomaly reported for a solid tumor. A small proportion of meningioma is characterized by clonal, numerical, or structural chromosomes changes other than monosomy 22, which are clinically related to a more agressive behavior of the tumor cells.

Classical cytogenetic analysis, fluorescent in situ hybridization (FISH), comparative genomic hybridization (CGH) have been performed to study six fresh tumors (primary and recurrent tumors). We also used an established high grade astrocytoma cell line, (G5), as a control for CGH experiments. For CGH analyses tumor and normal human DNA were labelled with FITC and rhodamine respectively and hybridized to slides with metaphase spreads from blood of a healthy donor. Images from metaphase cells were captured by using a cooled CCD camera, and the ratios of the FrrC/TRITC intensities were calculated along the chromosomes using the GENOSCAN software based on SCIL image and developed in Clermont-Ferrand. CGH experiments were used in order to resolve the high karyotype complexity with markers of unknown origin. FISH was performed following a modified version of the techinique described by Pinkel et al.

Classical karyotypes show a complete 22 monosomy in three cases, a I; 17 translocation in one case and the presence of undidentified chromosome markers.

CGH allows to identify the amount of chromosome 22 imbalances. FISH experiments confirm imbalances involving chromosome 7, 9, 10, 17,

22. These data show that CGH and FISH are indispensable tools to complement

standard cytogenetic analysis References 1 .Scheitghauer BW( 1990): Acta Neuropathol 80:343-354