Video_S1_Cryptometamorphosis

Video S1. A video illustrating a hypothesised scenario of isometric growth post-settlement in Gigantopelta chessoia versus the observed cryptometamorphosis, showing changes in the anatomy of the digestive system around the point of transition (3.5 mm to 12.2 mm body length). Simulated growth and rendering was done in Blender v2.79b

Cryptometamorphosis in Gigantopelta from Cryptic niche switching in a chemosymbiotic gastropod

A video illustrating a hypothesised scenario of isometric growth post-settlement in Gigantopelta chessoia versus the observed cryptometamorphosis, showing changes in the anatomy of the digestive system around the point of transition (3.5 mm to 12.2 mm body length). Simulated growth and rendering was done in Blender v2.79b

Image1.JPEG

<p>The elemental composition of calcite is of critical value in paleoceanographic reconstructions, yet little is known about biological processes underlying elemental uptake by foraminifers during calcification. Especially crucial in the understanding of elemental composition and distribution is the involvement of organic templates separating different layers of calcite forming the wall of a foraminiferal chamber. In this study, we applied the focused ion beam (FIB) scanning electron microscopy (SEM) technique to the site of calcification (SOC) in a newly growing chamber of Ammonia “beccarii”, a benthic foraminifer, to reveal the ultra- and microstructure during calcification. This allowed cross-sections of both soft and hard tissues, allowing detailed observation of the SOC across a series of calcification stages. For the first time, we show that numerous voids of calcareous layers and internal organic structures are present within the SOC during the calcification process. The series of SEM observations suggest that organic layers are actively involved in calcite precipitation. We provide the first evidence that the SOC is isolated from surrounding seawater during calcification. Our findings improve the understanding of foraminiferal biomineralization and characterize key conditions under which element partitioning and isotope fractionation occur.</p

Moldable Crystalline α‑Chitin Hydrogel with Toughness and Transparency toward Ocular Applications

A N-acetylated chitosan hydrogel was investigated for ocular applications. One of the drawbacks in the original hydrogel protocol, poor moldability, was circumvented by optimizing the addition of the acetylating agent, acetic acid anhydride (Ac2O), at −10 °C. This simple but significant optimization realized the preparation of N-acetylated chitosan hydrogels with a wider variety of parameters such as higher chitosan concentration and molecular weight, the use of a more benign solvent (ethanol replaced methanol), and the arbitral shapes ranging from microbeads and contact lenses to bulky blocks that could be gripped. The prepared N-acetylated chitosan hydrogels exhibited high transparency and integrity given the nanofibrous network made of highly crystalline α-chitin. Furthermore, the gel retained a regenerable character: an oven-dried gel was reswollen by emersion in an acid bath. These previously unnoticed advantages and the innate high biocompatibility of chitosan and chitin elevate N-acetylated chitosan hydrogel as a next-generation bio-derived soft material for ocular applications such as contact lenses, artificial corneas, and drug delivery vehicles

<i>Adipicola</i> mussels.

<p>Scanning electron micrographs of gill surfaces. (A)–(C) <i>Adipicola pacifica</i>. (A) & (B) Well-developed microvilli and numerous bacterial symbionts on the gill surface. Arrowheads indicate the symbionts and arrows indicate microvilli. (C) Higher magnification of the bacterial symbionts. Well-developed filamentous networks are visible. Arrowheads indicate the symbionts. (D) <i>Adipicola crypta</i>. The gill surface was flat and smooth and few bacteria are visible.</p

<i>Adipicola</i> mussels.

<p>Images of Fluorescence <i>in situ</i> hybridization (FISH) microscopy of bacterial symbionts in transverse sections of gill filaments of <i>A. pacifica</i> (A, B) and <i>A. crypta</i> (C, D) are shown. Hybridizations with the Symbiont A-specific probe SymA labeled with Alexa 647 (shown in red) and the Symbiont C-specific probe SymCx labeled with Alexa 555 (shown in green) are shown in A and B. Hybridizations with the <i>A. crypta</i> symbiont-specific probe SymAc labeled with Alexa 647 (shown in pink) are shown in C and D. All images are embedded sections (4-µm thickness) that were also stained with DAPI after hybridization (shown in blue). CZ: ciliated zone, LZ: lateral zone.</p

Hypothetical schemes for the evolution of symbiont-harboring mytilids.

<p>Mussel habitats and representative symbiotic forms in mussels from each habitat are shown. Open ellipse: mussel habitat, solid arrow: emigration of mussel, n: nucleus.</p

Operational taxonomic units (OTUs) used for phylogenetic analysis of host mussels and bacterial symbionts.

<p>Associated DDBJ accession numbers original to this study are shown in boldface type.</p

Stable isotopic compositions of soft tissues of whale-fall <i>Adipicola</i> mussels and whale tissues.

<p>(A) The δ¹³C and δ¹⁵N. (B) The δ¹³C and δ³⁴S. Open circle: <i>A. crypta</i>, solid circle: <i>A. pacifica</i>, open square: whale tissue. Each error bar indicates standard deviation among specimens.</p

<i>Adipicola</i> mussels.

<p>Transmission electron micrographs of transverse sections of ctenidial filaments. (A)–(C) <i>Adipicola pacifica</i>. (A) Epithelial cells of the ctenidial filament. Gram-negative bacterial symbionts (arrows) are visible on the surface of the cells. Arrowheads indicate pseudopodium-like structures. (B) Bacterial symbionts (arrows) contained in vacuoles accompanied by microvilli (arrowheads). (C) Intracellular degradation of symbionts. Relics of decomposed bacteria (arrows) located in vacuoles of host cells and accompanying host microvilli (arrowheads). (D) <i>Adipicola crypta</i>. Intracellular gram-negative symbiotic bacteria within epithelial cells of the ctenidial filament. Arrowheads indicate the symbionts in vacuoles and arrows indicate digested bacteria in lysosomes.</p