THE INFLUENCE OF TEMPERATURE ON THE KINETICS OF ALLOGRAFT REACTIONS IN A TROPICAL SPONGE AND A REEF CORAL

¹ Immunogenetics Group, School of Medicine and Dental Research Institute, University of California, Los Angeles, California, 90024, USA
² Hawaii Institute of Marine Biology, Kaneohe, Hawaii 96744, USA

Many tropical sponges and reef-building corals demonstrate highly discriminating transplantation immunity when grafted with allogeneic tissue. The speed of rejection changes seasonally, and therefore the role of temperature was investigated. Replicate parabiotic allografts of a Hawaiian sponge, Callyspongia diffusa, and a reef-coral, Montipora verrucosa, were exposed to three different temperature regimens: approximately 23°, 25°, and 27°C. The primary allograft reactions were extremely temperature dependent in both species; the median reaction times (MRT) for the first-set grafts at summer temperatures (27°C) were approximately half the winter temperature (23°C) MRTs. Significantly accelerated second-set reactions in the coral were similarly affected by temperature; however, maximally accelerated second-set reactions in the sponge were similar at all three temperatures. The primary mean reaction times for replicate grafts varied significantly among the individual genotypic combinations brought into parabiosis. Furthermore, different genotypic combinations responded to temperature changes with qualitatively distinctive reaction trends as well as different reaction times. Parabiotic allografts mimic intraspecific interactions that are a consequence of natural contact through growth of sedentary marine animals. The influence of temperature on the outcome of intraspecific competition suggests that temperature fluctuations could maintain high levels of genetic polymorphism within individual populations of sponges and corals.