Examples of molecular tools in T. brucei. There are at least eight drugs for selection (G418, Hygromycin, Puromycin, Phleomycin, Blasticidin, Nourseothricin/ClonNAT, Ganciclovir and FOA). Cells are typically grown in semi-defined media (SDM-79 for procyclic form [55], HMI-9 for bloodstream form [56]). Procyclic form cells readily grow up to a density of 1 × 107 cells ml−1 (1 × 106 cells ml−1 for bloodstream form cells) and can be frozen for long-term storage in liquid nitrogen. A subspecies, Trypanosoma brucei brucei, cannot infect humans owing to its sensitivity to human lytic factor [57], and is used in many research laboratories. Various monoclonal antibodies are also available [58]. Genetic exchange occurs under special circumstances (in the tsetse fly [59–61]), but it is not a widely practicable technique. Differentiation of life cycles can be reproduced in vitro [62–64]. GFP, green fluorescent protein; TAP, tandem affinity purification; YFP, yellow fluorescent protein.