American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

What temperature is necessary for probe storage in FISH procedures?

1. 0°C

2. -20°C

3. 4°C

4. Room temperature

The correct answer is: -20°C

The appropriate temperature for probe storage in FISH (Fluorescence In Situ Hybridization) procedures is typically -20°C. This temperature helps to preserve the integrity and functionality of the DNA probes utilized in the assay. Storing probes at -20°C slows down enzymatic reactions and degradation processes that could compromise their performance during hybridization. Keeping the probes at a lower temperature ensures prolonged stability, preventing denaturation or nonspecific binding, which could ultimately lead to inaccurate results in the FISH analysis. Other storage conditions, such as 4°C or room temperature, may lead to a decline in probe quality over time. Probes stored at 0°C may not be as stable as at -20°C, and while some reagents can be temporarily kept at 4°C for short periods, it is not ideal for long-term storage and can result in potential degradation. Hence, -20°C remains the most reliable and recommended storage condition for FISH probes.