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Sakai D, Nishikawa J, Kakiuchida H, Hirose E. Stack of cellular lamellae forms a silvered cortex to conceal the opaque organ in a transparent gastropod in epipelagic habitat. PeerJ 2022; 10:e14284. [PMID: 36325178 PMCID: PMC9620974 DOI: 10.7717/peerj.14284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/02/2022] [Indexed: 01/26/2023] Open
Abstract
Background Gelatinous zooplankton in epipelagic environments often have highly transparent bodies to avoid detection by their visual predators and prey; however, the digestive systems are often exceptionally opaque even in these organisms. In a holoplanktonic gastropod, Pterotrachea coronata, the visceral nucleus is an opaque organ located at the posterior end of its alimentary system, but this organ has a mirrored surface to conceal its internal opaque tissue. Results Our ultrastructural observation proved that the cortex of the visceral nucleus comprised a stack of thin cellular lamellae forming a Bragg reflector, and the thickness of lamellae (0.16 µm in average) and the spaces between the lamellae (0.1 µm in average) tended to become thinner toward inner lamellae. Based on the measured values, we built virtual models of the multilamellar layer comprising 50 lamellae and spaces, and the light reflection on the models was calculated using rigorous coupled wave analysis to evaluate their properties as reflectors. Our simulation supported the idea that the layer is a reflective tissue, and the thickness of the lamella/space must be chirped to reflect sunlight as white/silver light, mostly independent of the angle of incidence. Conclusions In P. coronata, the cortex of the visceral nucleus comprised multicellular lamellae that form a chirped Bragg reflector. It is distinct in structure from the intracellular Bragg structures of common iridophores. This novel Bragg reflector demonstrates the diversity and convergent evolution of reflective tissue using reflectin-like proteins in Mollusca.
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Affiliation(s)
- Daisuke Sakai
- School of Regional Innovation and Social Design Engineering, Kitami Institute of Technology, Kitami, Hokkaido, Japan
| | - Jun Nishikawa
- Department of Marine Biology, School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka, Japan
| | - Hiroshi Kakiuchida
- Innovative Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Aichi, Japan
| | - Euichi Hirose
- Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan
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Daugavet MA, Dobrynina MI, Shaposhnikova TG, Solovyeva AI, Mittenberg AG, Shabelnikov SV, Babkina IY, Grinchenko AV, Ilyaskina DV, Podgornaya OI. New putative phenol oxidase in ascidian blood cells. Sci Rep 2022; 12:14326. [PMID: 35995990 PMCID: PMC9395347 DOI: 10.1038/s41598-022-18283-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
The phenol oxidase system is ancient and ubiquitously distributed in all living organisms. In various groups it serves for the biosynthesis of pigments and neurotransmitters (dopamine), defence reactions and tissue hardening. Ascidians belong to subphylum Tunicata, which is considered the closest living relative to Vertebrates. Two phenol oxidases previously described for ascidians are vertebrate-like and arthropod-like phenol oxidases. In our present study, we described a new ascidian protein, Tuphoxin, with putative phenol oxidase function, which bears no sequence similarity with two enzymes described previously. The closest related proteins to Tuphoxin are mollusc haemocyanins. Unlike haemocyanins, which are oxygen transporting plasma proteins, Tuphoxin is synthesised in ascidian blood cells and secreted in the extracellular matrix of the tunic—ascidian outer coverings. Single mature transcript coding for this phenol oxidase can give several protein products of different sizes. Thus limited proteolysis of the initial protein is suggested. A unique feature of Tuphoxins and their homologues among Tunicata is the presence of thrombospondin first type repeats (TSP1) domain in their sequence which is supposed to provide interaction with extracellular matrix. The finding of TSP1 in the structure of phenol oxidases is new and we consider this to be an innovation of Tunicata evolutionary lineage.
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Affiliation(s)
- M A Daugavet
- Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia.
| | - M I Dobrynina
- Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | | | - A I Solovyeva
- Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia.,Zoological Institute of Russian Academy of Sciences, St. Petersburg, Russia
| | - A G Mittenberg
- Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - S V Shabelnikov
- Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia
| | - I Yu Babkina
- Saint-Petersburg State University, St. Petersburg, Russia
| | - A V Grinchenko
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Vladivostok, Russia
| | - D V Ilyaskina
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Vladivostok, Russia.,Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - O I Podgornaya
- Institute of Cytology of Russian Academy of Sciences, St. Petersburg, Russia.,Saint-Petersburg State University, St. Petersburg, Russia
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Substrate Selection of Ascidian Larva: Wettability and Nano-Structures. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2021. [DOI: 10.3390/jmse9060634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ascidians are marine sessile chordates that comprise one of the major benthic animal groups in marine ecosystems. They sometimes cause biofouling problems on artificial structures underwater, and non-indigenous, invasive ascidian species can potentially and seriously alter native faunal communities. Ascidian larvae are usually tadpole-shaped, negatively phototactic, and adhere on substrates by secreting a glue from their adhesive organs. Although larvae often prefer hydrophobic surfaces, such as a silicone rubber, for settlement, hydrophobic materials are often used to reduce occurrence of fouling organisms on artificial structures. This inconsistency may indicate that an attractive surface for larvae is not always suitable for settlement. Micro-scale structures or roughness may enhance the settlement of ascidian larvae, but settlement is significantly reduced by a nano-scale nipple array (or moth-eye structure), suggesting functional properties of similar structures found on the body surfaces of various invertebrates. The substrate preferences of larvae should be one of the important bases in considering measures against biofouling, and this review also discusses the potential uses of materials to safely reduce the impacts of invasive species.
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Hirose E, Sakai D, Iida A, Obayashi Y, Nishikawa J. Exumbrellar Surface of Jellyfish: A Comparative Fine Structure Study with Remarks on Surface Reflectance. Zoolog Sci 2021; 38:170-178. [PMID: 33812356 DOI: 10.2108/zs200111] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/30/2020] [Indexed: 11/17/2022]
Abstract
The exumbrellar surfaces of six pelagic cnidarians from three classes were ultra-structurally compared to reveal their structural diversity in relation to their gelatinous, transparent bodies. We examined two hydrozoans (Diphyes chamissonis and Colobonema sericeum), a cubozoan (Chironex yamaguchii), and three scyphozoans (Atolla vanhöffeni, Aurelia coerulea, and Mastigias papua). The exumbrellar surfaces of the mesoglea in D. chamissonis, Ch. yamaguchii, Au. coerulea, and M. papua were covered with a simple epidermis; the shapes of the epidermal cells were remarkably different among the species. The epidermal cells of Ch. yamaguchii and M. papua possessed an array of microvilli on the apical side. The array possibly reduced light reflectance and provided some other surface properties, as seen for the cuticular nipple array in tunicates, considering the length, width, and pitch of the microvilli. The reduction of light reflectance on the array of microvilli was supported by the simulation with rigorous coupled wave analysis (RCWA). Microvilli were sparse and did not form an array in metephyrae of Au. coerulea. The mesoglea matrix beneath the basal side of the epidermis was loose in all of the species. The exumbrellar side of the mesoglea was exposed only in the mesopelagic species, At. vanhöffeni and Co. sericeum, and electron-dense layer(s) covered the surface of the mesoglea. It is uncertain whether the exumbrellar epidermis is absent in these species or the epidermal cells are completely exfoliated during the sampling and handling processes. In the latter case, the electron-dense layer(s) on the mesoglea surface might originally underlie the epidermis.
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Affiliation(s)
- Euichi Hirose
- Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan,
| | - Daisuke Sakai
- School of Regional Innovation and Social Design Engineering, Kitami Institute of Technology, Koen-cho, Kitami, Hokkaido 090-8507, Japan
| | - Akane Iida
- Graduate School of Bioscience, Tokai University, Orido, Shimizu, Shizuoka 424-8610, Japan
| | - Yumiko Obayashi
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Jun Nishikawa
- School of Marine Science and Technology, Tokai University, Orido, Shimizu, Shizuoka 424-8610, Japan
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Phylogenetic comparison of egg transparency in ascidians by hyperspectral imaging. Sci Rep 2020; 10:20829. [PMID: 33257720 PMCID: PMC7709464 DOI: 10.1038/s41598-020-77585-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/12/2020] [Indexed: 12/01/2022] Open
Abstract
The transparency of animals is an important biological feature. Ascidian eggs have various degrees of transparency, but this characteristic has not yet been measured quantitatively and comprehensively. In this study, we established a method for evaluating the transparency of eggs to first characterize the transparency of ascidian eggs across different species and to infer a phylogenetic relationship among multiple taxa in the class Ascidiacea. We measured the transmittance of 199 eggs from 21 individuals using a hyperspectral camera. The spectrum of the visual range of wavelengths (400–760 nm) varied among individuals and we calculated each average transmittance of the visual range as bio-transparency. When combined with phylogenetic analysis based on the nuclear 18S rRNA and the mitochondrial cytochrome c oxidase subunit I gene sequences, the bio-transparencies of 13 species were derived from four different families: Ascidiidae, Cionidae, Pyuridae, and Styelidae. The bio-transparency varied 10–90% and likely evolved independently in each family. Ascidiella aspersa showed extremely high (88.0 ± 1.6%) bio-transparency in eggs that was maintained in the “invisible” larva. In addition, it was indicated that species of the Ascidiidae family may have a phylogenetic constraint of egg transparency.
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Hirose E, Nakayama K, Yanagida T, Nawata A, Kitamura SI. Measurement of Tunic Hardness in an Edible Ascidian, Halocynthia roretzi, with Remarks on Soft Tunic Syndrome. Zoolog Sci 2018; 35:548-552. [DOI: 10.2108/zs180072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Euichi Hirose
- Department of Chemistry, Biology, and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa 903-0213, Japan
| | - Kei Nakayama
- Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Tetsuya Yanagida
- Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Akatsuki Nawata
- Miyagi Prefecture Fisheries Technology Institute, Ishinomaki, Miyagi 986-2135, Japan
| | - Shin-Ichi Kitamura
- Center for Marine Environmental Studies (CMES), Ehime University, Matsuyama, Ehime 790-8577, Japan
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Cytoplasmic UV-R Absorption in an Integumentary Matrix (tunic) of Photosymbiotic Ascidian Colonies. Zool Stud 2018; 57:e33. [PMID: 31966273 DOI: 10.6620/zs.2018.57-33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/28/2018] [Indexed: 11/18/2022]
Abstract
Noburu Sensui and Euichi Hirose (2018) In didemnid ascidians with cyanobacterial symbionts, the tunic has a specific peak absorbing ultraviolet radiation (UV-R) due to the presence of ultraviolet (UV)-absorbing compounds, which probably include mycosporine-like amino acids (MAAs). The UV-R absorbing tunic is supposed to protect the symbionts in the common cloacal cavity of the host colony. The histological distribution of UV-R absorption in the tunic was examined using a UV light microscope equipped with a digital camera, from which the low-pass filter of the UV-sensitive image sensor was removed. The cell peripheries of tunic bladder cells and cell-like objects were visualized with the trans-illumination of UV light, indicating UV-R absorption at that site. In contrast, tunic matrix and vacuolar content of tunic bladder cells appeared to lack of UV-R absorption, allowing damaging wavelengths to penetrate. Accordingly, UV-absorbing compounds are expected to be contained in the cytoplasmic matrix of tunic bladder cells and possibly other types of tunic cells.
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