Systems and methods of automatically bleeding air from a primary ink delivery system, so little or no air is mixed with the ink once it reaches a secondary ink system containing print heads. A recessed downlight fixture includes a housing having an open end, an electrical power access port, a cooling module in the housing that is removably coupled to the electrical power access port, and a light source in the housing that is removably coupled to the electrical power access port. Methods of using the protein complexes and fusion proteins are also disclosed.