Abstract: A gas valve comprises a valve body having a flow passage therethrough between inlet port and outlet ports, a piston slidably located within the flow passage movable between a closed and an open position and a cavity defined by an opening in the valve body and a slidably movable surface, the slidably movable surface being operably connected to the piston. The gas valve further comprises a pre-charge passage extending from the flow passage to the inlet port to the cavity, a pilot line extending from the flow passage proximate to the outlet port to the cavity, a pilot valve located within the pilot line to control flow of gas through the pilot line and a solenoid operable to open or close the pilot valve. A method of opening a gas valve comprises actuating the solenoid to open the pilot valve, depressurizing the cavity so as to move the slidably movable surface and slidably displacing the piston to the open position.

Abstract: Gene promoters activated only during development of the fruiting body of filamentous fungi permit expression of large quantities of heterologous genes, even where such are otherwise toxic to the organism.