The purpose of the Cytogenetics Laboratory Shared Resource is to provide cytogenetic analysis, gene mapping and chromosomal microdissection services for members of the San Antonio Cancer Institute. The technical expertise and equipment required for cytogenetic analysis, gene mapping and chromosomal microdissection make it cost prohibitive and undesirable for independent investigators to perform these studies in their own laboratories. The past options for Cancer Center members have been to contract for these services commercially or collaborate with clinical services laboratories which are concerned with patient sample analysis. The objective of this core will be to provide San Antonio Cancer Institute members affordable comprehensive cytogenetic studies for research specimens for the actual costs of the services. a. Cytogenetic analysis of tumor specimens and cell lines Chromosomal analysis of cell lines or tumor specimens: Techniques which will be offered include G-banding (trypsin, Wright's stain, Borate), Q- banding, C- and R-banding, G-11, high resolution banding. 10 - 15 metaphase spreads will be analyzed and a karyotype will be produced. The laboratory is set up for analysis of chromosomes from a variety of tissue types including: tissue cultured cells (adherent or suspension cells) peripheral blood cells, bone marrow and solid tumor. Chromosomal analysis of human-rodent somatic cell hybrid cells will also be performed. b. Chromosomal in situ hybridization Techniques offered include (a) FISH (fluorescent in situ hybridization) analysis for chromosome labeling or gene mapping with cosmids and (b) radiolabeled in situ hybridization for gene mapping with small inserts. c. Chromosome microdissection and microcloning (CMM) Chromosome microdissection for the molecular analysis of specific chromosome regions will be offered. This recently described technique allows small pieces of chromatin to be selectively scrapped from chromosomes. This method provides clones for the starting points for molecular analysis from specific chromosome regions linked to specific diseases (Rohme et al., 1984; Ludecke et al., 1989). There are many specific chromosomal regions of interest associated with neoplasia that this procedure might prove invaluable for the generation of new genetic tumor markers. CMM is a method which provides for the rapid isolation of picogram quantities of DNA from targeted chromosome regions. CMM allows the rapid construction of molecular probes from chromosome regions associated with cancers. CMM therefore provides a new experimental approach to analyze specific chromosome regions associated with human diseases with significant morbidity and mortality. d. Technical improvements for genetic analysis Provide technical expertise and facilities for implementation of new techniques as they are developed (e.g., comparative genomic hybridization). The exciting technological advancement known as comparative genomic hybridization (Kallioniemi et al.,1 992) produces a map of DNA sequence copy number as a function of chromosomal location throughout the entire genetic genome. Test DNA (from cancer cells) and reference DNA (from normal cells) are differentially labeled and hybridized simultaneously to normal human peripheral blood chromosome metaphase spreads. This hybridization is detected with two different fluorochromes. Deletions, duplications or amplifications are observed as changes in the ration of the intensities of the two fluorochromes along the chromosome.
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