Laboratory phase‐contrast nanotomography of unstained <i>Bombus terrestris</i> compound eyes

Romell, Jenny; Jie, Vun Wen; Miettinen, Arttu; Baird, Emily; Hertz, Hans M.

doi:10.1111/jmi.13005

Cited by 11 publications

(11 citation statements)

References 45 publications

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“…To determine the accuracy of our DRA localization method, we took transverse sections of the rhabdoms in regions predicted to be DRA and non-DRA on a separate individual prepared and visualised them using transmission electron microscopy (Romell et al, 2021).…”

Section: Methodsmentioning

confidence: 99%

Novel methodology for localizing and studying the insect dorsal rim area morphology in 2D and 3D

Jie

Miettinen

Baird

2022

Preprint

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Polarized light-based navigation in insects is facilitated by a specialised polarisation-sensitive part of the eye known as the dorsal rim area (DRA). Existing methods to study the anatomy of the DRA are in most cases destructive and very time consuming. Here, we present a novel method that allows for DRA localization using 3D volumetric images acquired through micro-computed tomography in combination with 2D photographs. We used the method on size polymorphic buff-tailed bumblebees, Bombus terrestris. We found that the size of the DRA can be easily acquired from photographs of the dorsal part of the eye. An allometric analysis of the size of the DRA in relation to body size in B. terrestris showed that the DRA region increases with body size but not at the same rate. Using our method, we localised the DRA in a 3D volume rendering of the eye using 2D photos localization of an individual's DRA onto the volumetric image stack of the head allowed for individual-level descriptions of the ommatidial structures (lens, crystalline cones, rhabdoms) to be performed on three different eye regions (DRA, non-DRA, proximate to DRA). The only feature distinctly unique to the DRA ommatidia was the smaller dimension of crystalline cones in comparison to other regions. Using our novel methodology we provide the first individual-level description of DRA ommatidial features and a comparison of how the DRA area varies with body size in bumblebees.

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Section: Methodsmentioning

confidence: 99%

Novel methodology for localizing and studying the insect dorsal rim area morphology in 2D and 3D

Jie

Miettinen

Baird

2022

Preprint

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show abstract

“…To determine the accuracy of our DRA localization method, we took transverse sections of the rhabdoms in regions predicted to be DRA and non-DRA on a separate individual, and prepared and visualised them using transmission electron microscopy [68]. To determine the accuracy of our DRA localization method, we took transverse sections of the rhabdoms in regions predicted to be DRA and non-DRA on a separate individual, and prepared and visualised them using transmission electron microscopy [68].…”

Section: Localizing the Dra On A 3d Head Modelmentioning

confidence: 99%

Novel Methodology for Localizing and Studying Insect Dorsal Rim Area Morphology in 2D and 3D

Jie

Miettinen

Baird

2023

Insects

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Polarized light-based navigation in insects is facilitated by a polarization-sensitive part of the eye, the dorsal rim area (DRA). Existing methods to study the anatomy of the DRA are destructive and time-consuming. We presented a novel method for DRA localization, dissection, and measurement using 3D volumetric images from X-ray micro-computed tomography in combination with 2D photographs. Applying the method on size-polymorphic buff-tailed bumblebees, Bombus terrestris, we found that the DRA was easily obtainable from photographs of the dorsal eye region. Allometric analysis of the DRA in relation to body size in B. terrestris showed that it increased with the body size but not at the same rate. By localizing the DRA of individual bumblebees, we could also perform individual-level descriptions and inter-individual comparisons between the ommatidial structures (lens, crystalline cones, rhabdoms) of three different eye regions (DRA, non-DRA, proximate to DRA). One feature distinct to the bumblebee DRA was the smaller dimension of the crystalline cones in comparison to other regions of the eye. Using our novel methodology, we provide the first individual-level description of DRA ommatidial features and a comparison of how the DRA varies with body size in bumblebees.

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“…In previous studies, mammalian and insect eyes were proven to be suitable objects to be investigated by XPCT. 26,27 Also, there are indications that neurodegenerative diseases are preceded by degeneration of the retinal structure, making it an important object to study the origins and progression of conditions, such as Parkinson's disease 28 or Alzheimer's. 29 The retina consists of the following layers (optical nerve side to eyeball): choroid, retinal pigmented epithelium, layer of rods and cones, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, Ganglion cell layer, nerve fiber layer, and the internal limiting membrane where the incident light falls in.…”

Section: Introductionmentioning

confidence: 99%

“…Murine eyes were selected as test samples since they allow easy penetration of the stains and consist of multiple tissue layers as well as the retina, with all structures showing different chemical compositions and therefore different binding affinities. In previous studies, mammalian and insect eyes were proven to be suitable objects to be investigated by XPCT 26 , 27 . Also, there are indications that neurodegenerative diseases are preceded by degeneration of the retinal structure, making it an important object to study the origins and progression of conditions, such as Parkinson’s disease 28 or Alzheimer’s 29 .…”

Section: Introductionmentioning

confidence: 99%

Neodymium acetate as a contrast agent for X-ray phase-contrast tomography

Reichmann,

Ruhwedel,

Möbius

et al. 2023

J. Med. Imag.

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.PurposeX-ray phase-contrast tomography (XPCT) is a non-destructive, three-dimensional imaging modality that provides higher contrast in soft tissue than absorption-based CT and allows one to cover the cytoarchitecture from the centi- and millimeter scale down to the nanoscale. To further increase contrast and resolution of XPCT, for example, in view of addressing connectivity issues in the central nervous system (CNS), metal staining is indispensable. However, currently used protocols, for example, based on osmium and/or uranium are less suited for XPCT, due to an excessive β / δ-ratio. In this work, we explore the suitability of different staining agents for XPCT. Particularly, neodymium(III)-acetate (NdAc), which has recently been proposed as a non-toxic, non-radioactive easy to use alternative contrast agent for uranyl acetate (UAc) in electron microscopy, is investigated. Due to its vertical proximity to UAc in the periodic table, similar chemical but better suited optical properties for phase contrast can be expected.ApproachDifferently stained whole eye samples of wild type mouse and tissues of the CNS are embedded into EPON epoxy resin and scanned using synchrotron as well as with laboratory radiation. Phase retrieval is performed on the projection images, followed by tomographic reconstruction, which enables a quantitative analysis based on the reconstructed electron densities. Segmentation techniques and rendering software is used to visualize structures of interest in the sample.ResultsWe show that staining neuronal samples with NdAc enhances contrast, in particular for laboratory scans, allowing high-resolution imaging of biological soft tissue in-house. For the example of murine retina, specifically rods and cones as well as the sclera and the Ganglion cell layer seem to be targeted by the stain. A comparison of electron density by the evaluation of histograms allowed to determine quantitative measures to describe the difference between the examined stains.ConclusionThe results suggest NdAc to be an effective stain for XPCT, with a preferential binding to anionic groups, such as phosphate and carboxyl groups at cell surfaces, targeting certain layers of the retina with a stronger selectivity compared to other staining agents. Due to the advantageous X-ray optical properties, the stain seems particularly well-suited for phase contrast, with a comparably small number density and an overall superior image quality at laboratory sources.

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Laboratory phase‐contrast nanotomography of unstained Bombus terrestris compound eyes

Cited by 11 publications

References 45 publications

Novel methodology for localizing and studying the insect dorsal rim area morphology in 2D and 3D

Novel methodology for localizing and studying the insect dorsal rim area morphology in 2D and 3D

Novel Methodology for Localizing and Studying Insect Dorsal Rim Area Morphology in 2D and 3D

Neodymium acetate as a contrast agent for X-ray phase-contrast tomography

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