A new vertebrate courtship pheromone, PMF, affects female receptivity in a terrestrial salamander

Vertebrate pheromones that affect female receptivity have been documented only in salamanders. These courtship pheromones have been investigated most intensively in plethodontid salamanders. The source of the plethodontid courtship pheromone is the male's submandibular (mental) gland, which produces a multiprotein secretion. In earlier work with our main study species, Plethodon shermani (the red-legged salamander), an extract of protein secretions obtained from male mental glands acted to increase sexual receptivity in females. In addition, one particular protein in the gland secretion, plethodontid receptivity factor (PRF), could act alone to increase female receptivity. We now report that a second protein, termed ‘plethodontid modulating factor’ (PMF), acts oppositely to reduce female receptivity. The natural courtship pheromone blend thus includes two proteins that separately produce opposing messages, even though the combined effect of both proteins is to increase female receptivity.