Ethological dynamics in diorama environments

Sexual reproduction serves as a system for surviving adverse environments in many organisms. During the reproduction process, the step where gametes of opposite mating types/sexes meet each other and fuse efficiently must be crucial for the species. This study focuses on a fertilization system employed by the volvocine green algae, in which male gametes first develop as a compact colony of sperms (a sperm packet) and then disperse into individual sperms. Elucidation of the structural bases and molecular mechanism of this packet-individual conversion of the sperm will improve our understanding of a proto-intelligence for efficient reproduction. We previously found that Eudorina, a volvocine alga, is a suitable organisms for efficient induction of the sperm packet using a sex pheromone, and for analyzing the packet-individual conversion. This study aims to clarify the behavioral characteristics of both colonial and individual sperms of Eudorina, and to elucidate the cellular basis that enables the proper movement of both forms despite their fundamentally different body plan.