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Smith MR, Long EJ, Dhungana A, Dobson KJ, Yang J, Zhang X. Organ systems of a Cambrian euarthropod larva. Nature 2024; 633:120-126. [PMID: 39085610 PMCID: PMC11374701 DOI: 10.1038/s41586-024-07756-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 06/26/2024] [Indexed: 08/02/2024]
Abstract
The Cambrian radiation of euarthropods can be attributed to an adaptable body plan. Sophisticated brains and specialized feeding appendages, which are elaborations of serially repeated organ systems and jointed appendages, underpin the dominance of Euarthropoda in a broad suite of ecological settings. The origin of the euarthropod body plan from a grade of vermiform taxa with hydrostatic lobopodous appendages ('lobopodian worms')1,2 is founded on data from Burgess Shale-type fossils. However, the compaction associated with such preservation obscures internal anatomy3-6. Phosphatized microfossils provide a complementary three-dimensional perspective on early crown group euarthropods7, but few lobopodians8,9. Here we describe the internal and external anatomy of a three-dimensionally preserved euarthropod larva with lobopods, midgut glands and a sophisticated head. The architecture of the nervous system informs the early configuration of the euarthropod brain and its associated appendages and sensory organs, clarifying homologies across Panarthropoda. The deep evolutionary position of Youti yuanshi gen. et sp. nov. informs the sequence of character acquisition during arthropod evolution, demonstrating a deep origin of sophisticated haemolymph circulatory systems, and illuminating the internal anatomical changes that propelled the rise and diversification of this enduringly successful group.
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Affiliation(s)
- Martin R Smith
- Department of Earth Sciences, Durham University, Durham, UK.
| | - Emma J Long
- Department of Earth Sciences, Durham University, Durham, UK
- Science Group, Natural History Museum, London, UK
- Centre for Ecology and Conservation, University of Exeter, Cornwall, UK
| | | | - Katherine J Dobson
- Department of Earth Sciences, Durham University, Durham, UK
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, UK
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow, UK
| | - Jie Yang
- Institute of Palaeontology, Yunnan University, Chenggong, Kunming, China
| | - Xiguang Zhang
- Institute of Palaeontology, Yunnan University, Chenggong, Kunming, China
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Holst S, Miranda LS, Meyer P, Michalik P, Sötje I. Morphological analyses of the adult and juvenile stages of the stalked jellyfish Craterolophus convolvulus (Johnston, 1835) (Cnidaria: Staurozoa: Stauromedusae: Craterolophidae) using micro-CT. ZOOL ANZ 2021. [DOI: 10.1016/j.jcz.2021.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
Micro-computed X-ray tomography (μCT) coupled with visualization techniques such as three-dimensional reconstruction of internal morphological structures has opened up new pathways for analyzing the anatomy of nervous systems in intact specimens. The possibility for combining μCT with other techniques is one of the major advantages of μCT scanning, and the technical development of higher resolutions in lab-based μCT-scanners allows for investigating the anatomy of specimens in the sub-milimeter range. The European shore crab Carcinus maenas features a larval development over four zoeal and one megalopal stage with body lengths ranging from 500 μm to 2000 μm. The developing nervous system in the larvae of C. maenas is organized into a central brain which is connected via esophageal connectives with a ventral nerve chord and segmental ganglia. Since soft tissues such as the nervous tissues feature low contrasts compared to other tissues such as muscles or cuticularized body parts, the interpretation in μCT scans is challenging and needs some practice. The protocol described here is also applicable for larger specimens of a variety of species and spans over 2-3 days resulting in an image stack ready for postprocessing and visualization.
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Affiliation(s)
- Jakob Krieger
- Department of Cytology and Evolutionary Biology, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany.
| | - Franziska Spitzner
- Department of Cytology and Evolutionary Biology, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany
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Nischik ES, Krieger J. Evaluation of standard imaging techniques and volumetric preservation of nervous tissue in genetically identical offspring of the crayfish Procambarus fallax cf. virginalis (Marmorkrebs). PeerJ 2018; 6:e5181. [PMID: 30018856 PMCID: PMC6044273 DOI: 10.7717/peerj.5181] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 06/18/2018] [Indexed: 01/24/2023] Open
Abstract
In the field of comparative neuroanatomy, a meaningful interspecific comparison demands quantitative data referring to method-specific artifacts. For evaluating the potential of state-of-the-art imaging techniques in arthropod neuroanatomy, micro-computed X-ray microscopy (μCT) and two different approaches using confocal laser-scanning microscopy (cLSM) were applied to obtain volumetric data of the brain and selected neuropils in Procambarus fallax forma virginalis (Crustacea, Malacostraca, Decapoda). The marbled crayfish P. fallax cf. virginalis features a parthogenetic reproduction generating genetically identical offspring from unfertilized eggs. Therefore, the studied organism provides ideal conditions for the comparative analysis of neuroanatomical imaging techniques and the effect of preceding sample preparations of nervous tissue. We found that wet scanning of whole animals conducted with μCT turned out to be the least disruptive method. However, in an additional experiment it was discovered that fixation in Bouin’s solution, required for μCT scans, resulted in an average tissue shrinkage of 24% compared to freshly dissected and unfixed brains. The complete sample preparation using fixation in half-strength Karnovsky’s solution of dissected brains led to an additional volume decrease of 12.5%, whereas the preparation using zinc-formaldehyde as fixative resulted in a shrinkage of 5% in comparison to the volumes obtained by μCT. By minimizing individual variability, at least for aquatic arthropods, this pioneer study aims for the inference of method-based conversion factors in the future, providing a valuable tool for reducing quantitative neuroanatomical data already published to a common denominator. However, volumetric deviations could be shown for all experimental protocols due to methodological noise and/or phenotypic plasticity among genetically identical individuals. MicroCT using undried tissue is an appropriate non-disruptive technique for allometry of arthropod brains since spatial organ relationships are conserved and tissue shrinkage is minimized. Collecting tissue-based shrinkage factors according to specific sample preparations might allow a better comparability of volumetric data from the literature, even if another technique was applied.
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Affiliation(s)
- Emanuel S Nischik
- Zoological Institute and Museum, Cytology and Evolutionary Biology, University of Greifswald, Greifswald, Germany
| | - Jakob Krieger
- Zoological Institute and Museum, Cytology and Evolutionary Biology, University of Greifswald, Greifswald, Germany
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Spitzner F, Meth R, Krüger C, Nischik E, Eiler S, Sombke A, Torres G, Harzsch S. An atlas of larval organogenesis in the European shore crab Carcinus maenas L. (Decapoda, Brachyura, Portunidae). Front Zool 2018; 15:27. [PMID: 29989069 PMCID: PMC6035453 DOI: 10.1186/s12983-018-0271-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 05/30/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND The life history stages of brachyuran crustaceans include pelagic larvae of the Zoea type which grow by a series of moults from one instar to the next. Zoeae actively feed and possess a wide range of organ systems necessary for autonomously developing in the plankton. They also display a rich behavioural repertoire that allows for responses to variations in environmental key factors such as light, hydrostatic pressure, tidal currents, and temperature. Brachyuran larvae have served as distinguished models in the field of Ecological Developmental Biology fostering our understanding of diverse ecophysiological aspects such as phenotypic plasticity, carry-over effects on life-history traits, and adaptive mechanisms that enhance tolerance to fluctuations in environmental abiotic factors. In order to link such studies to the level of tissues and organs, this report analyses the internal anatomy of laboratory-reared larvae of the European shore crab Carcinus maenas. This species has a native distribution extending across most European waters and has attracted attention because it has invaded five temperate geographic regions outside of its native range and therefore can serve as a model to analyse thermal tolerance of species affected by rising sea temperatures as an effect of climate change. RESULTS Here, we used X-ray micro-computed tomography combined with 3D reconstruction to describe organogenesis in brachyuran larvae. We provide a detailed atlas of the larval internal organization to complement existing descriptions of its external morphology. In a multimethodological approach, we also used cuticular autofluorescence and classical histology to analyse the anatomy of selected organ systems. CONCLUSIONS Much of our fascination for the anatomy of brachyuran larvae stems from the opportunity to observe a complex organism on a single microscopic slide and the realization that the entire decapod crustacean bauplan unfolds from organ anlagen compressed into a miniature organism in the sub-millimetre range. The combination of imaging techniques used in the present study provides novel insights into the bewildering diversity of organ systems that brachyuran larvae possess. Our analysis may serve as a basis for future studies bridging the fields of evolutionary developmental biology and ecological developmental biology.
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Affiliation(s)
- Franziska Spitzner
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, D-27498 Helgoland, Germany
| | - Rebecca Meth
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, D-27498 Helgoland, Germany
| | - Christina Krüger
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
| | - Emanuel Nischik
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
| | - Stefan Eiler
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Svante Arrhenius väg 20A/F, 11418 Stockholm, Sweden
| | - Andy Sombke
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
| | - Gabriela Torres
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, D-27498 Helgoland, Germany
| | - Steffen Harzsch
- Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, Universität Greifswald, D-17498 Greifswald, Germany
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A simple setup for episcopic microtomy and a digital image processing workflow to acquire high-quality volume data and 3D surface models of small vertebrates. ZOOMORPHOLOGY 2017. [DOI: 10.1007/s00435-017-0386-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Kerbl A, Conzelmann M, Jékely G, Worsaae K. High diversity in neuropeptide immunoreactivity patterns among three closely related species of Dinophilidae (Annelida). J Comp Neurol 2017; 525:3596-3635. [PMID: 28744909 DOI: 10.1002/cne.24289] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 06/23/2017] [Accepted: 07/07/2017] [Indexed: 12/31/2022]
Abstract
Neuropeptides are conserved metazoan signaling molecules, and represent useful markers for comparative investigations on the morphology and function of the nervous system. However, little is known about the variation of neuropeptide expression patterns across closely related species in invertebrate groups other than insects. In this study, we compare the immunoreactivity patterns of 14 neuropeptides in three closely related microscopic dinophilid annelids (Dinophilus gyrociliatus, D. taeniatus and Trilobodrilus axi). The brains of all three species were found to consist of around 700 somata, surrounding a central neuropil with 3-5 ventral and 2-5 dorsal commissures. Neuropeptide immunoreactivity was detected in the brain, the ventral cords, stomatogastric nervous system, and additional nerves. Different neuropeptides are expressed in specific, non-overlapping cells in the brain in all three species. FMRFamide, MLD/pedal peptide, allatotropin, RNamide, excitatory peptide, and FVRIamide showed a broad localization within the brain, while calcitonin, SIFamide, vasotocin, RGWamide, DLamide, FLamide, FVamide, MIP, and serotonin were present in fewer cells in demarcated regions. The different markers did not reveal ganglionic subdivisions or physical compartmentalization in any of these microscopic brains. The non-overlapping expression of different neuropeptides may indicate that the regionalization in these uniform, small brains is realized by individual cells, rather than cell clusters, representing an alternative to the lobular organization observed in several macroscopic annelids. Furthermore, despite the similar gross brain morphology, we found an unexpectedly high variation in the expression patterns of neuropeptides across species. This suggests that neuropeptide expression evolves faster than morphology, representing a possible mechanism for the evolutionary divergence of behaviors.
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Affiliation(s)
- Alexandra Kerbl
- Marine Biological Section - Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Katrine Worsaae
- Marine Biological Section - Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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Smith FW, Bartels PJ, Goldstein B. A Hypothesis for the Composition of the Tardigrade Brain and its Implications for Panarthropod Brain Evolution. Integr Comp Biol 2017; 57:546-559. [DOI: 10.1093/icb/icx081] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Henne S, Sombke A, Schmidt-Rhaesa A. Immunohistochemical analysis of the anterior nervous system of the free-living nematode Plectus spp. (Nematoda, Plectidae). ZOOMORPHOLOGY 2017. [DOI: 10.1007/s00435-017-0347-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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