Dynamic organization of cortical actin filaments during the ooplasmic segregation of ascidianCionaeggs

Abstract

Locally distinct, transient realignments of cortical F-actin were found in live ascidian Ciona eggs during the first ooplasmic segregation by using fluorescence polarization-based molecular orientation imaging. These actin realignments are correlated with the directional movement of egg cytoplasm revealed with selective plane illumination microscopy.

On theindependent irritabilityof goldfish eggs and embryos – a living communication on the rhythmic yolk contractions in goldfish

“…The egg exhibits a range of dynamic behaviors during development and patterning such as cytoskeletal reorganisation, calcium signaling oscillations, waves, and contractile behavior (Brownlee and Dale, 1990; Deguchi et al, 2000; Ishii and Tani, 2021; Just, 1919, 1939; Kyozuka et al, 2008; Limatola et al, 2022; Santella and Chun, 2022; Sardet et al, 1998; Stricker, 1999) most evident immediately after egg activation and fertilization. Remarkably, in goldfish eggs and embryos (but not in those of closely-related carp and zebrafish) rhythmic contractions of the yolk emerge after some time elapsed from egg activation and fertilization and persist until gastrulation.…”

“…We hypothesize that the yolk contractions in goldfish are maintained by the cortical actomyosin network and/or calcium signaling. Both of these factors correlate spatiotemporally with contractile behavior in the ascidian egg after egg activation and fertilization (Brownlee and Dale, 1990; Ishii and Tani, 2021). Waves of calcium signaling are also involved in the deformation of mouse oocytes (Deguchi et al, 2000) and in the rhythmic contraction of the blastoderm in medaka embryos (Simon and Cooper, 1995).…”

“…Unlike the egg contractions mentioned above, which are short-lived and occur just after egg activation and fertilization (Brownlee and Dale, 1990; Deguchi et al, 2000; Ishii and Tani, 2021), some eggs and embryos also display rhythmic contractions that last until much later stages of development. For example, cell-autonomous periodic cortical waves of contraction (PeCoWaCo), linked to the softening of the actomyosin cortex, are evident during the cleavage stages preceding compaction in mouse embryos (Maître et al, 2015; Özgüç et al, 2022).…”

“…These dynamics are now known to have the capacity to carry spatiotemporal information that pre-determines later developmental events, e.g. the site of gastrulation in ascidians (Roegiers et al, 1995; Sardet et al, 2007), and are linked to emergent contractile behavior of the egg (Brownlee and Dale, 1990; Ishii and Tani, 2021; Kyozuka et al, 2008; Limatola et al, 2022) in both ascidian eggs (Brownlee and Dale, 1990; Ishii and Tani, 2021) and in mouse oocytes (Deguchi et al, 2000).…”