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Desyatirkina IA, Makarova AA, Pang S, Xu CS, Hess H, Polilov AA. Multiscale head anatomy of Megaphragma (Hymenoptera: Trichogrammatidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2023; 76:101299. [PMID: 37666087 DOI: 10.1016/j.asd.2023.101299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/10/2023] [Accepted: 08/15/2023] [Indexed: 09/06/2023]
Abstract
Methods of three-dimensional electron microscopy have been actively developed recently and open up great opportunities for morphological work. This approach is especially useful for studying microinsects, since it is possible to obtain complete series of high-resolution sections of a whole insect. Studies on the genus Megaphragma are especially important, since the unique phenomenon of lysis of most of the neuron nuclei was discovered in species of this genus. In this study we reveal the anatomical structure of the head of Megaphragma viggianii at all levels from organs to subcellular structures. Despite the miniature size of the body, most of the organ systems of M. viggianii retain the structural plan and complexity of organization at all levels. The set of muscles and the well-developed stomatogastric nervous system of this species correspond to those of larger insects, and there is also a well-developed tracheal system in the head of this species. Reconstructions of the head of M. viggianii at the cellular and subcellular levels were obtained, and of volumetric data were analyzed. A total of 689 nucleated cells of the head were reconstructed. The ultrastructure of M. viggianii is surprisingly complex, and the evolutionary benefits of such complexity are probably among the factors limiting the further miniaturization of parasitoid wasps.
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Affiliation(s)
- Inna A Desyatirkina
- Department of Entomology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
| | - Anastasia A Makarova
- Department of Entomology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Song Pang
- Janelia Research Campus of the Howard Hughes Medical Institute, Ashburn, USA; Yale School of Medicine, New Haven, CT, USA
| | - C Shan Xu
- Janelia Research Campus of the Howard Hughes Medical Institute, Ashburn, USA; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA
| | - Harald Hess
- Janelia Research Campus of the Howard Hughes Medical Institute, Ashburn, USA
| | - Alexey A Polilov
- Department of Entomology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
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The 3D ultrastructure of the chordotonal organs in the antenna of a microwasp remains complex although simplified. Sci Rep 2022; 12:20172. [PMID: 36424494 PMCID: PMC9691716 DOI: 10.1038/s41598-022-24390-4] [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: 07/08/2022] [Accepted: 11/15/2022] [Indexed: 11/26/2022] Open
Abstract
Insect antennae are astonishingly versatile and have multiple sensory modalities. Audition, detection of airflow, and graviception are combined in the antennal chordotonal organs. The miniaturization of these complex multisensory organs has never been investigated. Here we present a comprehensive study of the structure and scaling of the antennal chordotonal organs of the extremely miniaturized parasitoid wasp Megaphragma viggianii based on 3D electron microscopy. Johnston's organ of M. viggianii consists of 19 amphinematic scolopidia (95 cells); the central organ consists of five scolopidia (20 cells). Plesiomorphic composition includes one accessory cell per scolopidium, but in M. viggianii this ratio is only 0.3. Scolopale rods in Johnston's organ have a unique structure. Allometric analyses demonstrate the effects of scaling on the antennal chordotonal organs in insects. Our results not only shed light on the universal principles of miniaturization of sense organs, but also provide context for future interpretation of the M. viggianii connectome.
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Makarova AA, Veko EN, Polilov AA. Metamorphosis and denucleation of the brain in the miniature wasp Megaphragma viggianii (Hymenoptera: Trichogrammatidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2022; 70:101200. [PMID: 35961234 DOI: 10.1016/j.asd.2022.101200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Holometabolan brains undergo structural and allometric changes and complex reorganizations during metamorphosis. In minute egg parasitoids, brain formation is shifted to the late larva and young pupa, due to extreme de-embryonization. The brains of Megaphragma wasps undergo denucleation, the details of which remained unknown. We describe the morphological and volumetric changes in the brain of Megaphragma viggianii (Trichogrammatidae) during pupal development with emphasis on the lysis of nuclei and show that the absolute and relative volume of the brain decrease by a factor of 5 from prepupa to adult at the expense of the cell body rind. The first foci of lysis appear during early pupal development, but most nuclei (up to 97%) are lost between pharate adult and adult. The first signs of lysis (destruction of the nuclear envelopes) occur in pupae with red eyes. The number of lysis foci (organelle destruction and increasing number of lysosomes and degree of chromatin compaction) strongly increases in pupae with black eyes. The cell body rind volume strongly decreases during pupal development (in larger insects it increases slightly or remains unchanged). Elucidation of the lysis of nuclei in neurons and of the functioning of an anucleate brain is an important objective for neuroscience.
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Affiliation(s)
| | - Egor N Veko
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexey A Polilov
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
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Fischer S, Laue M, Müller CHG, Meinertzhagen IA, Pohl H. Ultrastructural 3D reconstruction of the smallest known insect photoreceptors: The stemmata of a first instar larva of Strepsiptera (Hexapoda). ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 62:101055. [PMID: 33975098 DOI: 10.1016/j.asd.2021.101055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 04/03/2021] [Accepted: 04/06/2021] [Indexed: 06/12/2023]
Abstract
Stemmata of strepsipteran insects represent the smallest arthropod eyes known, having photoreceptors which form fused rhabdoms measuring an average size of 1.69 × 1.21 × 1.04 μm and each occupying a volume of only 0.97-1.16 μm3. The morphology of the stemmata of the extremely miniaturized first instar larva of Stylops ovinae (Strepsiptera, Stylopidae) was investigated using serial-sectioning transmission electron microscopy (ssTEM). Our 3D reconstruction revealed that, despite different proportions, all three stemmata maintain the same organization: a biconvex corneal lens, four corneagenous cells and five photoreceptor (retinula) cells. No pigment-containing cell-types were found to adjoin the corneagenous cells. Whereas the retinula cells are adapted to the limited space by having laterally bulged median regions, containing mitochondria and the smallest nuclei yet reported for arthropods (1.37 μm3), special adaptations are found in the corneagenous cells which have cell volumes down to 1 μm3. The corneagenous cells lack nuclei and pigment granules and bear only a few mitochondria (up to three) or none at all. Morphological adaptations due to miniaturization are discussed in the context of photoreceptor function and the visual needs of the larva.
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Affiliation(s)
- Stefan Fischer
- Tübingen Structural Microscopy Core Facility, Center for Applied Geoscience, Eberhard-Karls-University Tübingen, Schnarrenbergstrasse 94-96, 72076 Tübingen, Germany; Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS, Canada B3H 4R2.
| | - Michael Laue
- Advanced Light and Electron Microscopy (ZBS 4), Robert Koch-Institut, Seestr. 10, 13353 Berlin, Germany
| | - Carsten H G Müller
- Zoological Institute and Museum, Department of General and Systematic Zoology, University of Greifswald, Loitzer Str. 26, 17489 Greifswald, Germany
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS, Canada B3H 4R2
| | - Hans Pohl
- Entomology Group, Institut für Zoologie und Evolutionsforschung, Friedrich-Schiller-Universität Jena, Erbertstraße 1, 07743 Jena, Germany
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Makarova AA, Veko EN, Polilov AA. Metamorphosis of the central nervous system of Trichogramma telengai (Hymenoptera: Trichogrammatidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 60:101005. [PMID: 33212369 DOI: 10.1016/j.asd.2020.101005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/27/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
During metamorphosis, the insect CNS undergoes both structural and allometric changes. Due to their extreme de-embryonization and parasitism, the formation of the CNS in egg parasitoids occurs at the late larval stage. Our study provides the first data on the morphological and volumetric changes of the CNS occurring during the pupal development of the parasitic wasp Trichogramma telengai Sorokina, 1987 (Trichogrammatidae). The prepupal-pupal development includes fusion and concentration of ganglia achieved by the loss of connectives. Volumetric analysis shows that during the pupal development the absolute body volume and CNS volume gradually decrease. The brain and thoracic synganglion slightly increase in volume during the pupal period and extremely decrease from late pupa to adult. The CNS neuropil volume increases from prepupa to adult. The mean cell diameter also decreases during the metamorphosis of the nervous system. The cell body rind volume decreases during pupal development; this decrease correlates with the decrease in the number of cells on the one hand and increase in the neuropilar volume on the other hand.
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Affiliation(s)
- Anastasia A Makarova
- Department of Entomology, Biological Faculty, Lomonosov Moscow State University, 119234, Moscow, Russia.
| | - Egor N Veko
- Department of Entomology, Biological Faculty, Lomonosov Moscow State University, 119234, Moscow, Russia
| | - Alexey A Polilov
- Department of Entomology, Biological Faculty, Lomonosov Moscow State University, 119234, Moscow, Russia
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Smith D, Starborg T. Serial block face scanning electron microscopy in cell biology: Applications and technology. Tissue Cell 2019; 57:111-122. [DOI: 10.1016/j.tice.2018.08.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/22/2018] [Accepted: 08/26/2018] [Indexed: 10/28/2022]
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Fischer S, Lu Z, Meinertzhagen IA. Three-dimensional ultrastructural organization of the ommatidium of the minute parasitoid wasp Trichogramma evanescens. ARTHROPOD STRUCTURE & DEVELOPMENT 2019; 48:35-48. [PMID: 30605733 DOI: 10.1016/j.asd.2018.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/28/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
Existing information on insect compound eyes is mainly limited to two-dimensional information derived from histological or ultrathin sections. These allow a basic description of eye morphology, but are limited in z-axis resolution because of the section thickness or intervals between sections, so that accurate volumetric information cannot be generated. Here we use serial-sectioning transmission electron microscopy to present a 3-D reconstruction at ultrastructural level of a complete ommatidium of a miniaturized insect compound eye. Besides the general presentation of the three dimensional arrangement of the different cell types within the ommatidium, the reconstruction allowed volumetric measurements and numerical analyses to be undertaken, revealing new insights into the number, size and distribution of cell organelles in insect ommatidia. Morphological features that can be related to miniaturization, namely the dimensions and displacement of nuclei, reduction of average pigment granule volume and loss of pigment granules in the terminals of the cone cells, the impact of metabolic activity of cell types on miniaturization, as well as maintenance of rhabdomere volume and limits to its miniaturization, are all discussed.
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Affiliation(s)
- Stefan Fischer
- Evolutionary Biology of Invertebrates, Institute of Evolution and Ecology, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28E, 72076 Tübingen, Germany; Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada.
| | - Zhiyuan Lu
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Minelli A, Fusco G. No limits: Breaking constraints in insect miniaturization. ARTHROPOD STRUCTURE & DEVELOPMENT 2019; 48:4-11. [PMID: 30496889 DOI: 10.1016/j.asd.2018.11.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/22/2018] [Accepted: 11/23/2018] [Indexed: 06/09/2023]
Abstract
Small arthropods are not simply scaled-down versions of their larger closest relatives, as changes in morphology and functional characters are largely governed by scaling laws. These same scaling laws set strict limits to size change toward smaller sizes. The evolution of extreme miniaturized forms involves the breaking of these constraints, by means of design innovations that allow evolutionary change to evade the limits posed by scaling laws. Here we review several cases studies in insects and other arthropods that illustrate this evolutionary path. We examine morphologies commonly recurring in miniaturized forms but not exclusive to them, morphologies exclusive to miniaturized forms and novel functional solutions supported by unconventional morphologies. We also discuss miniaturization and its evolvability taking into consideration arthropod postembryonic development and modular body organization. The modification of features commonly supposed not to change appears as a recurring pattern in arthropod miniaturization.
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Affiliation(s)
- Alessandro Minelli
- Department of Biology, University of Padova, Via Ugo Bassi 58B, I 35131, Padova, Italy.
| | - Giuseppe Fusco
- Department of Biology, University of Padova, Via Ugo Bassi 58B, I 35131, Padova, Italy.
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Abstract
In general, neurons in insects and many other invertebrate groups are individually recognizable, enabling us to assign an index number to specific neurons in a manner which is rarely possible in a vertebrate brain. This endows many studies on insect nervous systems with the opportunity to document neurons with great precision, so that in favourable cases we can return to the same neuron or neuron type repeatedly so as to recognize many separate morphological classes. The visual system of the fly's compound eye particularly provides clear examples of the accuracy of neuron wiring, allowing numerical comparisons between representatives of the same cell type, and estimates of the accuracy of their wiring.
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Affiliation(s)
- Ian A Meinertzhagen
- a Department of Psychology and Neuroscience , Life Sciences Centre, Dalhousie University , Halifax , Canada.,b Janelia Research Campus of Howard Hughes Medical Institute , Ashburn , VA , USA
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