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Lindgren, J., Nilsson, D. E., Sjövall, P., Jarenmark, M., Ito, S., Wakamatsu, K., . . . Ahlberg, P. (2019). Fossil insect eyes shed light on trilobite optics and the arthropod pigment screen. Nature
Open this publication in new window or tab >>Fossil insect eyes shed light on trilobite optics and the arthropod pigment screen
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2019 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687Article in journal (Refereed) Epub ahead of print
Abstract [en]

Fossilized eyes permit inferences of the visual capacity of extinct arthropods1–3. However, structural and/or chemical modifications as a result of taphonomic and diagenetic processes can alter the original features, thereby necessitating comparisons with modern species. Here we report the detailed molecular composition and microanatomy of the eyes of 54-million-year-old crane-flies, which together provide a proxy for the interpretation of optical systems in some other ancient arthropods. These well-preserved visual organs comprise calcified corneal lenses that are separated by intervening spaces containing eumelanin pigment. We also show that eumelanin is present in the facet walls of living crane-flies, in which it forms the outermost ommatidial pigment shield in compound eyes incorporating a chitinous cornea. To our knowledge, this is the first record of melanic screening pigments in arthropods, and reveals a fossilization mode in insect eyes that involves a decay-resistant biochrome coupled with early diagenetic mineralization of the ommatidial lenses. The demonstrable secondary calcification of lens cuticle that was initially chitinous has implications for the proposed calcitic corneas of trilobites, which we posit are artefacts of preservation rather than a product of in vivo biomineralization4–7. Although trilobite eyes might have been partly mineralized for mechanical strength, a (more likely) organic composition would have enhanced function via gradient-index optics and increased control of lens shape.

Place, publisher, year, edition, pages
Nature Publishing Group, 2019
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39862 (URN)10.1038/s41586-019-1473-z (DOI)2-s2.0-85071045838 (Scopus ID)
Note

Funding details: Vetenskapsrådet, VR, 642-2014-3773; Funding text 1: C. Tell processed our extant tiger crane-fly samples; R. Hauff and G. Dyke provided comparative ink sacs from fossil squids; and C. Rasmussen prepared the histological sections, performed the Fontana–Masson staining, and assisted during the transmission electron microscopy analysis. Financial support for this project was provided by a Swedish Research Council Grant for Distinguished Young Researchers (642-2014-3773) to J.L.

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-08-30Bibliographically approved
Lu, X., Sjövall, P., Soenen, H., Blom, J. & Andersson, M. (2019). Structural and chemical imaging analysis of bitumen. International Journal on Road Materials and Pavement Design
Open this publication in new window or tab >>Structural and chemical imaging analysis of bitumen
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2019 (English)In: International Journal on Road Materials and Pavement Design, ISSN 1468-0629, E-ISSN 2164-7402Article in journal (Refereed) Epub ahead of print
Abstract [en]

Microstructures of bitumen surfaces (both air-cooled and fractured) were imaged by atomic force microscopy (AFM) and chemically characterised by time-of-flight secondary ion mass spectrometry (TOF-SIMS). For certain air-cooled bitumen surfaces, bee structures were observed by AFM, and chemical explanation by wax crystallisation was confirmed by TOF-SIMS analysis. Unlike the air-cooled surfaces, the fracture surfaces generally did not show clear structure patterns. Furthermore, TOF-SIMS analysis was conducted on the tube-like or worm structures which were generated by environmental scanning electron microscopy (ESEM) on the bitumen surfaces. In general, very small chemical differences were observed between the structured and unstructured areas, as well as between different areas of the structure. To understand the formation of the ESEM structures, possible contributing factors were examined, from which a mechanism involving electron-induced heating was proposed.

Place, publisher, year, edition, pages
Taylor and Francis Ltd., 2019
Keywords
AFM, bitumen, ESEM, microstructure, TOF-SIMS, wax, Atomic force microscopy, Bituminous materials, Cooling systems, Organic polymers, Scanning electron microscopy, Secondary ion mass spectrometry, Waxes, Contributing factor, Environmental scanning electron microscopies (ESEM), Fracture surfaces, Time of flight secondary ion mass spectrometry, ToF SIMS, TOF-SIMS analysis, Chemical analysis
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39930 (URN)10.1080/14680629.2019.1661274 (DOI)2-s2.0-85071732430 (Scopus ID)
Available from: 2019-09-19 Created: 2019-09-19 Last updated: 2019-09-19Bibliographically approved
Oorni, K., Lehti, S., Sjövall, P. & Kovanen, P. T. (2019). Triglyceride-Rich Lipoproteins as a Source of Proinflammatory Lipids in the Arterial Wall. Current Medicinal Chemistry, 26(9), 1701-1710
Open this publication in new window or tab >>Triglyceride-Rich Lipoproteins as a Source of Proinflammatory Lipids in the Arterial Wall
2019 (English)In: Current Medicinal Chemistry, ISSN 0929-8673, E-ISSN 1875-533X, Vol. 26, no 9, p. 1701-1710Article in journal (Refereed) Published
Abstract [en]

Apolipoprotein B -containing lipoproteins include triglyceride-rich lipoproteins (chylomicrons and their remnants, and very low-density lipoproteins and their remnants) and cholesterol-rich low-density lipoprotein particles. Of these, lipoproteins having sizes below 70-80 nm may enter the arterial wall, where they accumulate and induce the formation of atherosclerotic lesions. The processes that lead to accumulation of lipoprotein-derived lipids in the arterial wall have been largely studied with a focus on the low-density lipoprotein particles. However, recent observational and genetic studies have discovered that the triglyceriderich lipoproteins and their remnants are linked with cardiovascular disease risk. In this review, we describe the potential mechanisms by which the triglyceride-rich remnant lipoproteins can contribute to the development of atherosclerotic lesions, and highlight the differences in the atherogenicity between low-density lipoproteins and the remnant lipoproteins.[on SciFinder (R)]

Keywords
chylomicron, vldl, atherosclerosis, cholesterol, inflammation, remnant, triglyceride.
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39208 (URN)10.2174/0929867325666180530094819 (DOI)29848270 (PubMedID)
Available from: 2019-06-20 Created: 2019-06-20 Last updated: 2019-06-20Bibliographically approved
Lu, X., Sjövall, P., Soenen, H., Blom, J. & Andersson, M. (2019). Visualization and chemical analysis of bitumen microstructures. In: RILEM Bookseries: . Paper presented at RILEM 252-CMB-Symposium on Chemo Mechanical Characterization of Bituminous Materials RILEM 252-CMB 2018: RILEM 252-CMB Symposium (pp. 168-173).
Open this publication in new window or tab >>Visualization and chemical analysis of bitumen microstructures
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2019 (English)In: RILEM Bookseries, 2019, p. 168-173Conference paper, Published paper (Refereed)
Abstract [en]

Microstructures of bitumen were investigated using atomic force microscopy (AFM) and environmental scanning electron microscopy (ESEM), and a chemical characterization was successfully carried out using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The bee structures were observed by AFM, for which a chemical explanation by wax was confirmed by the TOF-SIMS analysis. A tube pattern or worm structures were generated and visualized by ESEM on bitumen surfaces. Chemical differences between the structured and unstructured areas, as well as between different areas of the structure, were observed. A mechanism for the structure formation on bitumen surface during ESEM analysis is suggested.

Keywords
AFM, Bitumen structure, ESEM, TOF-SIMS
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35220 (URN)10.1007/978-3-030-00476-7_27 (DOI)2-s2.0-85053413366 (Scopus ID)
Conference
RILEM 252-CMB-Symposium on Chemo Mechanical Characterization of Bituminous Materials RILEM 252-CMB 2018: RILEM 252-CMB Symposium
Available from: 2018-10-10 Created: 2018-10-10 Last updated: 2019-06-20Bibliographically approved
Sjövall, P., Skedung, L., Gregoire, S., Biganska, O., Clément, F. & Luengo, G. S. (2018). Imaging the distribution of skin lipids and topically applied compounds in human skin using mass spectrometry. Scientific Reports, 8(1), Article ID 16683.
Open this publication in new window or tab >>Imaging the distribution of skin lipids and topically applied compounds in human skin using mass spectrometry
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 16683Article in journal (Refereed) Published
Abstract [en]

The barrier functions of skin against water loss, microbial invasion and penetration of xenobiotics rely, in part, on the spatial distribution of the biomolecular constituents in the skin structure, particularly its horny layer (stratum corneum). However, all skin layers are important to describe normal and dysfunctional skin conditions, and to develop adapted therapies or skin care products. In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with scanning electron microscopy (SEM) was used to image the spatial distribution of a variety of molecular species, from stratum corneum down to dermis, in cross-section samples of human abdominal skin. The results demonstrate the expected localization of ceramide and saturated long-chain fatty acids in stratum corneum (SC) and cholesterol sulfate in the upper part of the viable epidermis. The localization of exogenous compounds is demonstrated by the detection and imaging of carvacrol (a constituent of oregano or thyme essential oil) and ceramide, after topical application onto ex vivo human skin. Carvacrol showed pronounced accumulation to triglyceride-containing structures in the deeper parts of dermis. In contrast, the exogenous ceramide was found to be localized in SC. Furthermore, the complementary character of this approach with classical ex vivo skin absorption analysis methods is demonstrated.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36385 (URN)10.1038/s41598-018-34286-x (DOI)30420715 (PubMedID)2-s2.0-85056347342 (Scopus ID)
Available from: 2018-11-22 Created: 2018-11-22 Last updated: 2019-06-19Bibliographically approved
Lu, X., Sjövall, P., Soenen, H. & Andersson, M. (2018). Microstructures of bitumen observed by environmental scanning electron microscopy (ESEM) and chemical analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Fuel, 229, 198-208
Open this publication in new window or tab >>Microstructures of bitumen observed by environmental scanning electron microscopy (ESEM) and chemical analysis using time-of-flight secondary ion mass spectrometry (TOF-SIMS)
2018 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 229, p. 198-208Article in journal (Refereed) Published
Abstract [en]

The aim of this study is to characterize structures induced on bitumen surfaces under analysis by environmental scanning electron microscopy (ESEM), and to examine possible contributing factors to the formation of their formation. Various bitumen samples are investigated, including soft and hard, as well as polymer modified bitumen. Chemical characterization is carried out by time-of-flight secondary ion mass spectrometry (TOF-SIMS), combined with principle component analysis (PCA). The study shows that, for soft bitumen, a tube pattern or worm structure is rapidly formed during ESEM analysis, but for hard bitumen, a longer exposure time is needed to develop a structure. The structures on the hard bitumen are also denser as compared to those on the soft bitumen. When sample specimens are deformed or stretched, the orientation of the created deformation is clearly reflected in the structures formed under ESEM, and for soft bitumen, the structure disappears overnight in vacuum but reappears with the same pattern upon repeated ESEM analysis. TOF-SIMS shows small but consistent chemical differences, indicating higher aliphatic and lower aromatic contents on the surface of the structured area compared to the unstructured area. Based on an estimated temperature increase on the bitumen surface due to the electron-beam irradiation, it is speculated that the ESEM-induced worm structure may be attributed to evaporation of volatiles, surface hardening and local expansion. In addition, under the electron-beam exposure, certain chemical reactions (e.g. breaking of chemical bonds, chain scission and crosslinking) may take place, possibly resulting in the observed chemical differences between the structured and unstructured areas.

Keywords
Bitumen, Surface microstructure, ESEM, TOF-SIMS
National Category
Other Chemistry Topics Materials Chemistry
Identifiers
urn:nbn:se:ri:diva-33855 (URN)10.1016/j.fuel.2018.05.036 (DOI)2-s2.0-85047070237 (Scopus ID)
Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2019-06-19Bibliographically approved
Hannestad, J., Höök, F. & Sjövall, P. (2018). Nanometer-scale molecular organization in lipid membranes studied by time-of-flight secondary ion mass spectrometry. Biointerphases, 13(3), Article ID 03B408.
Open this publication in new window or tab >>Nanometer-scale molecular organization in lipid membranes studied by time-of-flight secondary ion mass spectrometry
2018 (English)In: Biointerphases, ISSN 1934-8630, E-ISSN 1559-4106, Vol. 13, no 3, article id 03B408Article in journal (Refereed) Published
Abstract [en]

The organization of lipid membranes plays an important role in a wide range of biological processes at different length scales. Herein, the authors present a procedure based on time-of-flight secondary ion mass spectrometry (ToF-SIMS) to characterize the nanometer-scale ordering of lipids in lipid membrane structures on surfaces. While ToF-SIMS is a powerful tool for label-free analysis of lipid-containing samples, its limited spatial resolution prevents in-depth knowledge of how lipid properties affect the molecular assembly of the membrane. The authors overcome this limitation by measuring the formation of lipid dimers, originating in the same nanometer-sized primary ion impact areas. The lipid dimers reflect the local lipid environment and thus allow us to characterize the membrane miscibility on the nanometer level. Using this technique, the authors show that the chemical properties of the constituting lipids are critical for the structure and organization of the membrane on both the nanometer and micrometer length scales. Our results show that even at lipid surface compositions favoring two-phase systems, lipids are still extracted from solid, gel phase, domains into the surrounding fluid supported lipid bilayer surrounding the gel phase domains. The technique offers a means to obtain detailed knowledge of the chemical composition and organization of lipid membranes with potential application in systems where labeling is not possible, such as cell-derived supported lipid bilayers.

National Category
Biophysics Analytical Chemistry
Identifiers
urn:nbn:se:ri:diva-33290 (URN)10.1116/1.5019794 (DOI)2-s2.0-85041912418 (Scopus ID)
Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2019-06-19Bibliographically approved
Schweitzer, M., Zheng, W., Moyer, A., Sjövall, P. & Lindgren, J. (2018). Preservation potential of keratin in deep time. PLoS ONE, 13(11)
Open this publication in new window or tab >>Preservation potential of keratin in deep time
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2018 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 11Article in journal (Refereed) Published
Abstract [en]

Multiple fossil discoveries and taphonomic experiments have established the durability of keratin. The utility and specificity of antibodies to identify keratin peptides has also been established, both in extant feathers under varying treatment conditions, and in feathers from extinct organisms. Here, we show localization of feather-keratin antibodies to control and heat-treated feathers, testifying to the repeatability of initial data supporting the preservation potential of keratin. We then show new data at higher resolution that demonstrates the specific response of these antibodies to the feather matrix, we support the presence of protein in heat-treated feathers using ToF-SIMS, and we apply these methods to a fossil feather preserved in the unusual environment of sinter hot springs. We stress the importance of employing realistic conditions such as sediment burial when designing experiments intended as proxies for taphonomic processes occurring in the fossil record. Our data support the hypothesis that keratin, particularly the β-keratin that comprises feathers, has potential to preserve in fossil remains.

National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:ri:diva-36631 (URN)10.1371/journal.pone.0206569 (DOI)2-s2.0-85057465903 (Scopus ID)
Note

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Available from: 2018-12-14 Created: 2018-12-14 Last updated: 2019-06-19Bibliographically approved
Lindgren, J., Sjövall, P., Thiel, V., Zheng, W., Ito, S., Wakamatsu, K., . . . Schweitzer, M. H. (2018). Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur. Nature, 564(7736), 359-365
Open this publication in new window or tab >>Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur
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2018 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 564, no 7736, p. 359-365Article in journal (Refereed) Published
Abstract [en]

Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-37275 (URN)10.1038/s41586-018-0775-x (DOI)2-s2.0-85058887475 (Scopus ID)
Note

Funding details: North Carolina State University, NCSU, ECCS-1542015; Funding details: Vetenskapsrådet; Funding details: EAR-1344198; Funding details: Allianz Industrie Forschung, AiF; Funding details: Knut och Alice Wallenbergs Stiftelse; Funding details: North Carolina State University, NCSU; .

Available from: 2019-01-18 Created: 2019-01-18 Last updated: 2019-06-19Bibliographically approved
Pace, H., Hannestad, J., Armonious, A., Adamo, M., Agnarsson, B., Gunnarsson, A., . . . Höök, F. (2018). Structure and Composition of Native Membrane Derived Polymer-Supported Lipid Bilayers. Analytical Chemistry, 90(21), 13065-13072
Open this publication in new window or tab >>Structure and Composition of Native Membrane Derived Polymer-Supported Lipid Bilayers
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2018 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 90, no 21, p. 13065-13072Article in journal (Refereed) Published
Abstract [en]

Over the last two decades, supported lipid bilayers (SLBs) have been extensively used as model systems to study cell membrane structure and function. While SLBs have been traditionally produced from simple lipid mixtures, there has been a recent surge in compositional complexity to better mimic cellular membranes and thereby bridge the gap between classic biophysical approaches and cell experiments. To this end, native cellular membrane derived SLBs (nSLBs) have emerged as a new category of SLBs. As a new type of biomimetic material, an analytical workflow must be designed to characterize its molecular composition and structure. Herein, we demonstrate how a combination of fluorescence microscopy, neutron reflectometry, and secondary ion mass spectrometry offers new insights on structure, composition, and quality of nSLB systems formed using so-called hybrid vesicles, which are a mixture of native membrane material and synthetic lipids. With this approach, we demonstrate that the nSLB formed a continuous structure with complete mixing of the synthetic and native membrane components and a molecular stoichiometry that essentially mirrors that of the hybrid vesicles. Furthermore, structural investigation of the nSLB revealed that PEGylated lipids do not significantly thicken the hydration layer between the bilayer and substrate when on silicon substrates; however, nSLBs do have more topology than their simpler, purely synthetic counterparts. Beyond new insights regarding the structure and composition of nSLB systems, this work also serves to guide future researchers in producing and characterizing nSLBs from their cellular membrane of choice.

Keywords
Biomimetics, Cell membranes, Cytology, Fluorescence microscopy, Lipid bilayers, Lipids, Mixtures, Secondary ion mass spectrometry, Substrates, Cellular membranes, Compositional complexity, Continuous structures, Molecular compositions, Neutron reflectometry, Silicon substrates, Structural investigation, Supported lipid bilayers, Structure (composition)
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-36374 (URN)10.1021/acs.analchem.8b04110 (DOI)2-s2.0-85056285757 (Scopus ID)
Available from: 2018-11-27 Created: 2018-11-27 Last updated: 2019-06-20Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2696-7215

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