In this respect, it is interesting to note that the heating rate explained more than 78% of the variation in Bcl2:Bax transcripts in A. millepora during our thermal stress experiments. This result suggests that the heating rate could be an important environmental driver of this molecular response in the host rather than duration and intensity of thermal anomalies. However, because the thermal treatments used in this study varied in both the average temperature and the heating rate, the effects observed on the level of expression of Bcl-2 family members are attributable to some combination of these 2 factors. Future studies should therefore include thermal treatments with tight control of temperature in order to precise the relative contributions of each factor on the molecular regulation of apoptosis in corals. This study provides further evidence that Tulathromycin B corals can regulate apoptosis in response to thermal stress. Bleaching is nevertheless an extremely dynamic event with many different triggers, responses and consequences to coral-dinoflagellate symbiosis. Understanding the cellular dynamics and the mechanisms driving the breakdown of this symbiosis will require many further studies but this is a critical step to predict future bleaching events and coral mortality under a changing climate. The formation of embryonic tissues is a key feature in generating diversity in animal development. After cell fate is established, cell-cell signaling and intracellular signal transduction pathways instruct cells to undergo cell shape changes. These cell shape changes are necessary for cell movement, a basic process that underlies embryonic development and is largely accomplished by regulation of the actin cytoskeleton. Actin dynamics is required for the migration of individual groups of cells, as in border cell migration in the Drosophila ovary, or large groups of cells, such as those involved in gastrulation in the developing fly embryo. One common feature of cell rearrangements via the actin cytoskeleton is the involvement of the Rho family of GTPases. Widely conserved across species and involved in seemingly diverse developmental processes including cell migration, phagocytosis, and myoblast fusion, the Rho GTPases are key signaling molecules that impinge upon actin cytoskeletal reorganization. Several classes of GTPase regulatory proteins have been identified, including the GTPase-activating proteins, guanine nucleotide exchange factors, and guanine nucleotide dissociation inhibitors. In particular, the GEFs regulate GTPase activity by exchanging the inactive, GDP-bound Rac to the active, GTP-bound state. It is thought that GEFs are a crucial intermediate that signal from upstream cell surface receptors to mediate GTPase activation. Some GEFs directly associate with membrane receptors, while others are associated via an intermediate complex. In flies, two neuronally expressed Rac GEFs have been identified that exemplify this in development of the central nervous system. Trio physically interacts with the Netrin receptor Frazzled to regulate chemoattraction, while Son of sevenless associates with the Roundabout receptor through the SH2-SH3 adaptor protein Dreadlocks to control axon repulsion. Vertebrate cell culture studies show this region is required for membrane localization. In flies, the DHR1 domain is not essential for recruitment to the membrane, but is essential for myoblast fusion as deletion of the DHR1 domain fails to rescue mbc mutant embryos in functional rescue assays. Although the SH3-domain containing protein Crk is capable of binding the C-terminal proline-rich region of both DOCK180 and Mbc, it is not 3,4,5-Trimethoxyphenylacetic acid always essential in vivo. A direct interaction between vertebrate DOCK180 and CrkII is not required for apoptotic cell removal. Conventional GEFs bind nucleotide-free Rac via their DH domain, while the CDM proteins use the DHR2 region. Deletion or mutation of this domain results in a loss of Rac binding and activation. A DOCK-Rac protein complex is sufficient for Rac activation, but may be enhanced by DOCK180 bound to ELMO.