1. A calcium‐mediated actin redistribution at egg activation in Drosophila
- Author
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Anna H. York-Andersen, Qinan Hu, Timothy T. Weil, Benjamin W. Wood, and Mariana F. Wolfner
- Subjects
0301 basic medicine ,Cytoplasm ,chemistry.chemical_element ,Embryonic Development ,macromolecular substances ,Biology ,Calcium ,Drosophila development ,Calcium in biology ,03 medical and health sciences ,0302 clinical medicine ,Human fertilization ,Oogenesis ,Genetics ,Animals ,Calcium Signaling ,Actin ,Research Articles ,030219 obstetrics & reproductive medicine ,Embryogenesis ,Oocyte activation ,Cell Biology ,Actin cytoskeleton ,Actins ,Cell biology ,Egg activation ,Actin Cytoskeleton ,030104 developmental biology ,chemistry ,Fertilization ,embryonic structures ,Oocytes ,calcium wave ,Drosophila ,oocyte‐to‐embryo transition ,Intracellular ,actin organization ,Developmental Biology ,Research Article - Abstract
Egg activation is the essential process in which mature oocytes gain the competency to proceed into embryonic development. Many events of egg activation are conserved, including an initial rise of intracellular calcium. In some species, such as echinoderms and mammals, changes in the actin cytoskeleton occur around the time of fertilization and egg activation. However, the interplay between calcium and actin during egg activation remains unclear. Here, we use imaging, genetics, pharmacological treatment, and physical manipulation to elucidate the relationship between calcium and actin in living Drosophila eggs. We show that, before egg activation, actin is smoothly distributed between ridges in the cortex of the dehydrated mature oocytes. At the onset of egg activation, we observe actin spreading out as the egg swells though the intake of fluid. We show that a relaxed actin cytoskeleton is required for the intracellular rise of calcium to initiate and propagate. Once the swelling is complete and the calcium wave is traversing the egg, it leads to a reorganization of actin in a wavelike manner. After the calcium wave, the actin cytoskeleton has an even distribution of foci at the cortex. Together, our data show that calcium resets the actin cytoskeleton at egg activation, a model that we propose to be likely conserved in other species., Initiation of egg activation in Drosophila results in a dispersal of the actin cytoskeleton, which is required for a calcium wave to pass through the egg and set in motion key downstream events. This calcium wave, in turn, is required for reorganization of the actin cytoskeleton, which occurs in a wavelike manner. This study suggests a highly coregulated calcium and actin signaling network in Drosophila oocytes during egg activation.
- Published
- 2019