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Cytogenetic Services for Stem Cell and Transgenics Quality Control: Karyotyping |
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Since traditional cytogenetics methods gather data on a series of single cells, their greatest strength is the ability to detect chromosomal abnormalities at low frequencies. G-band metaphase chromsome analysis and karyotyping is the primary tool for assuring that cell lines retain normal diploid chromosome complements and therefore essentially normal genomes within the resolution limit of 5 to 10 megabases. The Coriell Cytogenetics Laboratory was provided this service to the Coriell Cell Repositories since 1973. We have analyzed a large range of cell types from a large range of species. The CCL has offered this service to other clients since 1999. During that time we have analyzed over 1200 mouse embryonic stem cell (MESC) lines for stabile diploid karyotypes. This service offers assurance to transgenics facilities that they are not expending time and effort attempting to generate chimeras using MESCs with abnormalities that will compromise the chimeras germline transmission, fertilty, or the ability to produce otherwise normal progeny.
Even low frequencies of trisomy 8 cells or trisomy 11 cells can be a matter of concern since they confer a selective advantage and can overgrow cultures in small number of passages.
Duplications are commonly observed in MESC lines. These abnormalities are not picked up in counts of uniformly stained chromosomes even when they are large.
Some balanced translocations may be ascertainable without G-band analysis but these are the exception.
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