Developmental Table and Three-Dimensional Embryological Image Resource of the Ascidian Ascidiella aspersa

Abstract

Ascidiella aspersa is an ascidian in the class of chordates—the closest relatives of vertebrates. A. aspersa is a potential model organism for bio-imaging studies due to its extremely transparent embryos as well as is a globally distributed cosmopolitan species. However, there is no standard developmental table for this organism. Here, as a first step to establish A. aspersa as a model organism, we report a standard developmental table as a web-based digital image resource. This resource used confocal laser scanning microscopy to scan more than 3,000 cross-sectional images and 3D-reconstructed images of A. aspersa embryos during embryogenesis. With reference to the standardized developmental table of Ciona intestinalis type A, 26 different developmental stages (Stages 1–26) from fertilized eggs to hatched larvae were redefined for A. aspersa. Cell lineages up to the cleavage period were annotated: The cleavage patterns, the embryonic morphology, and the developmental time were then compared with Ciona. We found that the cleavage patterns and developmental time up to the neurula period in A. aspersa were extremely conserved versus. Ciona. The ratio of the trunk and tail length in the tailbud period were smaller than Ciona indicating a relatively short tail. In addition, the timing of the bending of the tail is earlier than Ciona. This A. aspersa standard 3D digital resource is essential for connecting different omics data to different spatiotemporal hierarchies and is useful for a system-level understanding of chordate development and evolution.

Multimodal factor evaluation system for organismal transparency by hyperspectral imaging

“…We established controlled environmental conditions for the seawater at 20°C, 33 ppt salinity, and pH 8.0, previously employed in general ascidian biological experiments [ 15 , 16 ]. The transparency of A .…”

“…We established controlled environmental conditions for the seawater at 20˚C, 33 ppt salinity, and pH 8.0, previously employed in general ascidian biological experiments [15,16] While temperature and salinity alterations are correlated with bio-transparency, no significant correlations were apparent between the bio-transparency and pH (R 2 = 0.4). Bio-transparency displayed comparatively minor fluctuations across the pH range of 3.4-8.06, with its pinnacle of 88.1% observed at pH 5.73.…”

Physical modeling of embryonic transcriptomes identifies collective modes of gene expression

“…This organism displays several attractive features, which we now discuss, that make it an ideal setting to develop our approach. The ascidian cell lineage is invariant, with the same series of synchronous cell divisions occurring in each embryo [12][13][14], Fig. 1A, which also provides a consistent way to name cells across embryos [12].…”