Clonal cell line selection is the process of isolating a single, genetically homogeneous population of cells from a mixed population of cells. This is typically done to establish a stable cell line that expresses a specific gene or phenotype of interest.

The process of clonal cell line selection typically involves plating the mixed population of cells at a very low density on a suitable growth medium. This allows individual cells to grow and form discrete colonies, each of which represents a clonal population of cells that originated from a single cell.

Once the colonies have formed, individual colonies can be picked and transferred to new plates or wells for further expansion and analysis. The colonies can be screened using various methods to identify those that express the desired gene or phenotype of interest. For example, if the cell line was generated using a fluorescent reporter gene, colonies can be screened for fluorescence using a fluorescence microscope or flow cytometer.

Clonal cell line selection can be a time-consuming process, as it may take several rounds of colony picking and screening to identify the desired clonal population. It is also important to ensure that the selected clonal population is genetically stable and does not exhibit any unwanted mutations or phenotypic changes over time.

In some cases, clonal cell line selection can be carried out using automated systems, such as cell sorters or colony-picking robots, to increase the efficiency and throughput of the process.