Comparative binding of antibody to a mate recognition pheromone on female Brachionus plicatilis and Brachionus rotundiformis (Rotifera)

Abstract

The work of Kazutsugu Hirayama over the past 25 years promoted the wide use of the marine rotifer Brachionus plicatilis as an experimental model in zooplankton ecology. His reports about the nature of genetic variation in the B. plicatilis complex stimulated us to investigate how mate recognition maintains species boundaries. For the past several years, we have examined chemical communication between female and male B. plicatilis. Here we report on the comparative binding of polyclonal antibody against the mate recognition pheromone (MRP) to three B. plicatilis strains and three B. rotundiformis strains. Quantification of anti-MRP binding permits investigation of how the female mating signal differs among closely related Brachionus species and strains. Antibody binding reflects differentiation independent of the male receptor which has been described elsewhere. Anti-MRP bound to females of all six strains and was localized in the corona. Antibody binding greatly reduced mating in all three B. plicatilis strains. However, antibody binding significantly reduced mating in only one of the B. rotundiformis strains. The MRP of both species has a similar molecular weight, but the differential binding suggests that the mate recognition pheromone on females has differentiated in B. plicatilis and B. rotundiformis.