Temperature control on the stage of the microscope

Temperature control is an important issue for applications in single cell research. The need to control temperature during experiments arises because cell responses are temperature-dependent. Especially in applications using fluorescent probes, adequate control of the temperature is critical, since dissociation constants of fluorescent probes such as Fura-2 are also highly dependent on temperature. (Lattanzio 1990, for review see Moore 1990). Video microscopy setups are highly susceptible to heat loss due to the extensive interface of the incubation chamber with the surroundings. One approach to controlling temperature is to heat the entire setup; however, for practical reasons, such as the need to have access to the incubation chamber during the experiment, this may not be feasible. Another approach is to heat only certain essential components of the setup; however, in this case it is vital to examine carefully whether the desired temperature is actually reached and if temperature control is. constant in the vicinity of the cells in the incubation chamber. Oscillations in the temperature due to inadequate control may cause apparent oscillations in, e.g., intracellular calcium concentrations measured using Fura-2.