106
ANITA RAUCH
ber of actual DNA binding sites. The signal number may be artificially
decreased by:
- insufficient tissue penetrability, resulting in minor hybridization efficiency
- a certain number of two actual signals lying so close together that they
appear as one
- analysis of damaged or overlapping cells
or increased by:
- signal splitting due to dispersed DNA
- signal splitting due to S or G2-phase cells
- signal imitating by bacteria or other background fluorescence
False negative signals from insufficient tissue penetrability may be reduced by optimal tissue pretreatment, while the fact that a certain number
of signals sticking together simulating a single signal has to be addressed
Fig. 2. FISH with probe VYSIS LSI 20q13 (red [rJ) and control probe VYSIS CEP 18 (green
[gl) to epithelial cells from urinary sediment of a child with mosaicism of an isochromosome 20q (cell with three red signals) in 13.7% of urinary cells
ANITA RAUCH
ber of actual DNA binding sites. The signal number may be artificially
decreased by:
- insufficient tissue penetrability, resulting in minor hybridization efficiency
- a certain number of two actual signals lying so close together that they
appear as one
- analysis of damaged or overlapping cells
or increased by:
- signal splitting due to dispersed DNA
- signal splitting due to S or G2-phase cells
- signal imitating by bacteria or other background fluorescence
False negative signals from insufficient tissue penetrability may be reduced by optimal tissue pretreatment, while the fact that a certain number
of signals sticking together simulating a single signal has to be addressed
Fig. 2. FISH with probe VYSIS LSI 20q13 (red [rJ) and control probe VYSIS CEP 18 (green
[gl) to epithelial cells from urinary sediment of a child with mosaicism of an isochromosome 20q (cell with three red signals) in 13.7% of urinary cells