ORCID Profile
0000-0002-9160-2239
Current Organisations
University of Belgrade
,
University of Montenegro
,
US Geological Survey
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Publications
Naturally Drug-Loaded Chitin: Isolation and Applications
Publisher: MDPI AG
Date: 10-10-2019
DOI: 10.3390/MD17100574
Abstract: Naturally occurring three-dimensional (3D) biopolymer-based matrices that can be used in different biomedical applications are sustainable alternatives to various artificial 3D materials. For this purpose, chitin-based structures from marine sponges are very promising substitutes. Marine sponges from the order Verongiida (class Demospongiae) are typical ex les of demosponges with well-developed chitinous skeletons. In particular, species belonging to the family Ianthellidae possess chitinous, flat, fan-like fibrous skeletons with a unique, microporous 3D architecture that makes them particularly interesting for applications. In this work, we focus our attention on the demosponge Ianthella flabelliformis (Linnaeus, 1759) for simultaneous extraction of both naturally occurring (“ready-to-use”) chitin scaffolds, and biologically active bromotyrosines which are recognized as potential antibiotic, antitumor, and marine antifouling substances. We show that selected bromotyrosines are located within pigmental cells which, however, are localized within chitinous skeletal fibers of I. flabelliformis. A two-step reaction provides two products: treatment with methanol extracts the bromotyrosine compounds bastadin 25 and araplysillin-I N20 sulfamate, and a subsequent treatment with acetic acid and sodium hydroxide exposes the 3D chitinous scaffold. This scaffold is a mesh-like structure, which retains its capillary network, and its use as a potential drug delivery biomaterial was examined for the first time. The results demonstrate that sponge-derived chitin scaffolds, impregnated with decamethoxine, effectively inhibit growth of the human pathogen Staphylococcus aureus in an agar diffusion assay.
Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core
Publisher: Copernicus GmbH
Date: 29-10-2014
Abstract: Abstract. Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales spanning millennia, and are thus useful to examine the role of fire in the carbon cycle and climate system. Here we use the specific biomarker levoglucosan together with black carbon and ammonium concentrations from the North Greenland Eemian (NEEM) ice cores (77.49° N, 51.2° W 2480 m a.s.l) over the past 2000 years to infer changes in boreal fire activity. Increases in boreal fire activity over the periods 1000–1300 CE and decreases during 700–900 CE coincide with high-latitude NH temperature changes. Levoglucosan concentrations in the NEEM ice cores peak between 1500 and 1700 CE, and most levoglucosan spikes coincide with the most extensive central and northern Asian droughts of the past millennium. Many of these multi-annual droughts are caused by Asian monsoon failures, thus suggesting a connection between low- and high-latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the Greenland Ice Cap. During major fire events, however, isotopic analyses of dust, back trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.
High latitude Southern Hemisphere fire history during the Mid-Late Holocene (750–6000 yr BP)
Publisher: Copernicus GmbH
Date: 21-12-2017
DOI: 10.5194/CP-2017-158
Abstract: Abstract. Abstract. High latitude Southern Hemisphere fire history was reconstructed by determining the specific biomarker levoglucosan in ice cores from the TALos Dome Ice CorE drilling project (TALDICE) during the Mid-Late Holocene (750–6000 yr BP). Potassium was also analyzed in order to provide a comparison with another fire proxy to create a more robust biomass burning record. The levoglucosan record is characterized by a long-term increase with higher rates starting at ~ 4000 yr BP and higher peaks between 1500 and 2500 yr BP. Comparisons with charcoal syntheses help evaluate fire sources, showing a possible higher contribution from Patagonian fires rather than Australian biomass burning. We interpret the anomalous increase in levoglucosan centred at ~ 2000 yr BP as a combination of the atmospheric transport pathway and the interplay between climatic factors.
Halogen species record Antarctic sea ice extent over glacial–interglacial periods
Publisher: Copernicus GmbH
Date: 12-07-2013
Abstract: Abstract. Sea ice is an integral part of the earth's climate system because it affects planetary albedo, sea-surface salinity, and the atmosphere–ocean exchange of reactive gases and aerosols. Bromine and iodine chemistry is active at polar sea ice margins with the occurrence of bromine explosions and the biological production of organoiodine from sea ice algae. Satellite measurements demonstrate that concentrations of bromine oxide (BrO) and iodine oxide (IO) decrease over sea ice toward the Antarctic interior. Here we present speciation measurements of bromine and iodine in the TALDICE (TALos Dome Ice CorE) ice core (159°11' E, 72°49' S 2315 m a.s.l.) spanning the last 215 ky. The Talos Dome ice core is located 250 km inland and is sensitive to marine air masses intruding onto the Antarctic Plateau. Talos Dome bromide (Br−) is positively correlated with temperature and negatively correlated with sodium (Na). Based on the Br−/Na seawater ratio, bromide is depleted in the ice during glacial periods and enriched during interglacial periods. Total iodine, consisting of iodide (I−) and iodate (IO3−), peaks during glacials with lower values during interglacial periods. Although IO3− is considered the most stable iodine species in the atmosphere it was only observed in the TALDICE record during glacial maxima. Sea ice dynamics are arguably the primary driver of halogen fluxes over glacial–interglacial timescales, by altering the distance between the sea ice edge and the Antarctic plateau and by altering the surface area of sea ice available to algal colonization. Based on our results we propose the use of both halogens for examining Antarctic variability of past sea ice extent.
Naturally Prefabricated Marine Biomaterials: Isolation and Applications of Flat Chitinous 3D Scaffolds from Ianthella labyrinthus (Demospongiae: Verongiida)
Publisher: MDPI AG
Date: 15-10-2019
DOI: 10.3390/IJMS20205105
Abstract: Marine sponges remain representative of a unique source of renewable biological materials. The demosponges of the family Ianthellidae possess chitin-based skeletons with high biomimetic potential. These three-dimensional (3D) constructs can potentially be used in tissue engineering and regenerative medicine. In this study, we focus our attention, for the first time, on the marine sponge Ianthella labyrinthus Bergquist & Kelly-Borges, 1995 (Demospongiae: Verongida: Ianthellidae) as a novel potential source of naturally prestructured bandage-like 3D scaffolds which can be isolated simultaneously with biologically active bromotyrosines. Specifically, translucent and elastic flat chitinous scaffolds have been obtained after bromotyrosine extraction and chemical treatments of the sponge skeleton with alternate alkaline and acidic solutions. For the first time, cardiomyocytes differentiated from human induced pluripotent stem cells (iPSC-CMs) have been used to test the suitability of I. labyrinthus chitinous skeleton as ready-to-use scaffold for their cell culture. Results reveal a comparable attachment and growth on isolated chitin-skeleton, compared to scaffolds coated with extracellular matrix mimetic Geltrex®. Thus, the natural, unmodified I. labyrinthus cleaned sponge skeleton can be used to culture iPSC-CMs and 3D tissue engineering. In addition, I. labyrinthus chitin-based scaffolds demonstrate strong and efficient capability to absorb blood deep into the microtubes due to their excellent capillary effect. These findings are suggestive of the future development of new sponge chitin-based absorbable hemostats as alternatives to already well recognized cellulose-based fabrics.
Comparative carbon cycle dynamics of the present and last interglacial
Publisher: Elsevier BV
Date: 04-2016
A multi-decadal geochemical record from Rano Aroi (Easter Island/Rapa Nui): Implications for the environment, climate and humans during the last two millennia
Publisher: Elsevier BV
Date: 09-2021
Prospects for reconstructing paleoenvironmental conditions from organic compounds in polar snow and ice
Publisher: Elsevier BV
Date: 03-2018
Speciation analysis of iodine and bromine at picogram-per-gram levels in polar ice
Publisher: Springer Science and Business Media LLC
Date: 17-02-2012
DOI: 10.1007/S00216-012-5806-0
Abstract: Iodine and bromine species participate in key atmospheric reactions including the formation of cloud condensation nuclei and ozone depletion. We present a novel method coupling a high-performance liquid chromatography with ion chromatography and inductively coupled plasma mass spectrometry, which allows the determination of iodine (I) and bromine (Br) species (IO(3)(-), I(-), Br(-), BrO(3)(-) ) at the picogram-per-gram levels presents in Antarctic ice. Chromatographic separation was achieved using an IONPAC® AS16 Analytical Column with NaOH as eluent. Detection limits for I and Br species were 5 to 9 pg g(-1) with an uncertainty of less than 2.5% for all considered species. Inorganic iodine and bromine species have been determined in Antarctic ice core s les, with concentrations close to the detection limits for iodine species, and approximately 150 pg g(-1) for Br(-). Although iodate (IO(3)(-)) is the most abundant iodine species in the atmosphere, only the much rarer iodide (I(-)) species was present in Antarctic Holocene ice. Bromine was found to be present in Antarctic ice as Br(-).
Iron speciation in aerosol dust influences iron bioavailability over glacial‐interglacial timescales
Publisher: American Geophysical Union (AGU)
Date: 27-04-2013
DOI: 10.1002/GRL.50296
PaCTS 1.0: A Crowdsourced Reporting Standard for Paleoclimate Data
Publisher: American Geophysical Union (AGU)
Date: 10-2019
DOI: 10.1029/2019PA003632
High-latitude Southern Hemisphere fire history during the mid- to late Holocene (6000–750 BP)
Publisher: Copernicus GmbH
Date: 21-06-2018
Abstract: Abstract. We determined the specific biomass burning biomarker levoglucosan in an ice core from the TALos Dome Ice CorE drilling project (TALDICE) during the mid- to late Holocene (6000–750 BP). The levoglucosan record is characterized by a long-term increase with higher rates starting at ∼ 4000 BP and peaks between 2500 and 1500 BP. The anomalous increase in levoglucosan centered at ∼ 2000 BP is consistent with other Antarctic biomass burning records. Multiple atmospheric phenomena affect the coastal Antarctic Talos Dome drilling site, where the Southern Annular Mode (SAM) is the most prominent as the Southern Annular Mode Index (SAMA) correlates with stable isotopes in precipitation throughout the most recent 1000 years of the ice core. If this connection remains throughout the mid- to late Holocene, then our results demonstrate that changes in biomass burning, rather than changes in atmospheric transport, are the major influence on the TALDICE levoglucosan record. Comparisons with charcoal syntheses help evaluate fire sources, showing a greater contribution from southern South American fires than from Australian biomass burning. The levoglucosan peak centered at ∼ 2000 BP occurs during a cool period throughout the Southern Hemisphere, yet during a time of increased fire activity in both northern and southern Patagonia. This peak in biomass burning is influenced by increased vegetation in southern South America from a preceding humid period, in which the vegetation desiccated during the following cool, dry period. The Talos Dome ice core record from 6000 to ∼ 750 BP currently does not provide clear evidence that the fire record may be strongly affected by anthropogenic activities during the mid- to late Holocene, although we cannot exclude at least a partial influence.
Europe on fire three thousand years ago: Arson or climate?
Publisher: American Geophysical Union (AGU)
Date: 28-06-2015
DOI: 10.1002/2015GL064259
Erosion rates of the Bhutanese Himalaya determined using in situ-produced 10Be
Publisher: Elsevier BV
Date: 03-2015
Related Organisations
Universita Ca Foscari Dipartimento Di Scienze Ambientali
Location: Italy
University Of Massachusetts Amherst
Location: United States of America
Related Funding Activities
No related grants have been discovered for Natalie Kehrwald.