| 1. |
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| 2. |
- Cheregi, Otilia, et al.
(author)
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Transcriptome analysis reveals insights into adaptive responses of two marine microalgae species to Nordic seasons
- 2023
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In: Algal Research. - 2211-9264. ; 74
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Journal article (peer-reviewed)abstract
- There is an increasing interest in algae-based biomass produced outdoors in natural and industrial settings for biotechnological applications. To predict the yield and biochemical composition of the biomass, it is important to understand how the transcriptome of species and strains of interest is affected by seasonal changes. Here we studied the effects of Nordic winter and summer on the transcriptome of two phytoplankton species, namely the diatom Skeletonema marinoi (Sm) and the eustigmatophyte Nannochloropsis granulata (Ng), recently identified as potentially important for biomass production on the west coast of Sweden. Cultures were grown in photobioreactors in simulated Nordic summer and winter, and the gene expression in two phases was quantified by Illumina RNA-sequencing. Five paired comparisons were made among the four conditions. Sm was overall more responsive to seasons since 70 % of the total transcriptome (14,783 genes) showed differential expression in at least one comparison as compared to 1.6 % (1403 genes) for Ng. For both species, we observed larger differences between the seasons than between the phases of the same season. In summer phase 1, Sm cells focused on photosynthesis and polysaccharide biosynthesis. Nitrate assimilation and recycling of intracellular nitrogen for protein biosynthesis were more active in summer phase 2 and throughout winter. Lipid catabolism was upregulated in winter relative to summer to supply carbon for respiration. Ng favored lipid accumulation in summer, while in winter activated different lipid remodeling pathways as compared to Sm. To cope with winter, Ng upregulated breakdown and transport of carbohydrates for energy production. Taken together, our transcriptome data reveal insights into adaptive seasonal responses of Sm and Ng important for biotechnological applications on the west coast of Sweden, but more work is required to decipher the molecular mechanisms behind these responses.
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| 3. |
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| 4. |
- Ekendahl, Susanne, 1965, et al.
(author)
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Energieffektiv odling av marina mikroalger vid den svenska västkusten - potentiella applikationer : RISE Rapport 2020: 72
- 2020
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Reports (other academic/artistic)abstract
- An energy-efficient cultivation method for microalgae has been further developed for the Nordic climate, specifically for the Swedish west coast. The principle for the cultivation process has earlier been developed by RISE for freshwater microalgae. In this project, we have used marine species, and thereby also seawater, in the cultivation. Utilization of natural seawater lowers the environmental impact since, during some circumstances, freshwater may become limiting even in Sweden. The aim of the study was to investigate if selected marine species could be rotated during the year to achieve a longer cultivation season and increased production of energy-rich algal biomass. Winter, spring and summer at the Swedish west coast were simulated in cultivation experiments in laboratory bioreactors with the species Skeletonema marinoi, usually thriving and blooming on the west coast in winter and spring, and Nannochloropsis granulata, which blooms in summer and produces high amounts of lipids. Nannochloropsis was shown to be more suitable for cultivation during spring and summer, when it comes to production of biomass and energy, while Skeletonema grew better during winter and displayed a higher uptake of phosphate than Nannochloropsis. The productivity of Nannochloropsis was in the same range as that of a previously studied freshwater microalgal species, Tetradesmus obliquus. We have shown the principle for a rotational cultivation strategy and that species adapted for a cold climate can give higher productivity during the cold season. Nevertheless, the selected species (Skeletonema) generally showed too low productivity when cultivated during winter to be energy efficient. More species need to be studied to identify those with a high productivity during winter conditions. Even if cold-adapted species are less productive than the summer-adapted ones, considering the available sunlight, they could still be used to prolong the growth season. The cultivation process of Nannochloropsis could also be optimized in an outdoor environment to prolong the season in different ways, since it was tolerant to cold conditions. In practice, the work-related consequences of a rotational cultivation should be weighed against its benefits for each application. Possible applications mainly include cleaning of air and seawater, production of energy, biomass and biomaterials for the industry.
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| 5. |
- Gilbert, F., et al.
(author)
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2-D optical quantification of particle reworking activities in marine surface sediments
- 2003
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In: JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY. - 0022-0981. ; 285, s. 251-263
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Journal article (peer-reviewed)abstract
- Particle and solute transport by faunal activities may significantly influence rates and pathways of organic matter mineralization during early diagenesis in surface sediments. One of the most frequently utilized techniques to quantify benthic biological reworking activities involves the calculation of a biodiffusion coefficient (D-b) estimated from model predictions of 1-D tracer distribution patterns. This technique is labor-intensive and time-demanding. Furthermore, it is normally used for measurements over several days and averages overall transport mechanisms from 3-D to 1-D on a cm scale. In the frame of this work, we developed a new technique based on the nondestructive screening of fluorescent particles (luminophores) using optical discrimination and CCD camera detection of fluorescence (2-D). At a site characterized by a dense population of the brittle star Amphiura filiformis and a high biodiffusion coefficient (obtained from 1-D distributions; D-b = 3 5.5 +/- 3.7 cm(-2) year(-1); n = 3), the optical reworking coefficient (ORC), estimated from the 2-D luminophore distribution patterns, was calculated (ORC = 27.4 +/- 9.1 DeltaQ cm(-2) h(-1); n=24). A nondestructive 2-D approach to quantify particle reworking may provide a powerful and complementary tool to further understand particle transport by the benthic fauna in surface sediments. The optical technique for 2-D detection of luminophores is relatively fast and easy to perform, with the ability to detect small scale (mm) particle movements on a time resolution of minutes or less. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 6. |
- Hakonen, Aron, 1970, et al.
(author)
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Applications of imaging optodes
- 2007
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In: Pittsburg Conference on Analytical Chemistry (PITTCON).
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Conference paper (peer-reviewed)
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| 7. |
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| 8. |
- Hakonen, Aron, 1970, et al.
(author)
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Plasmonic nanoparticle interactions for high-performance imaging fluorosensors
- 2011
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In: CHEMICAL COMMUNICATIONS. - 1359-7345. ; 47:12, s. 3433-3435
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Journal article (peer-reviewed)abstract
- We demonstrate a nanoparticle based ratiometric fluorosensor suitable for non-invasive high-resolution imaging of complex samples. Coextraction generates a movement of a solvatochromic dye, with a consequent shift from plasmophore coupled emission towards longer wavelength scattering enhanced emission. The nanoparticle doped sensors confirmed superior sensitivity, reversibility, durability and overall image quality.
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| 9. |
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| 10. |
- Karlsson, Anna, 1967, et al.
(author)
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Detection of glycoprotein receptors on blotting membranes by binding of live bacteria and amplification by growth.
- 1995
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In: Analytical biochemistry. - : Elsevier BV. - 0003-2697. ; 224:1, s. 390-4
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Journal article (peer-reviewed)abstract
- Conditions have been adapted for detecting bacteria bound to glycoprotein receptors on blotting membranes using a self-enhancing detection method based on bacterial growth. Neutrophil plasma membrane proteins, mediating adherence of mannose-binding type-1-fimbriated Escherichia coli and concanavalin A (Con A) to intact human neutrophils, were separated by SDS-PAGE and transferred onto a polyvinylidene difluoride (PVDF) membrane. The PVDF membrane was immersed in a suspension of mannose-binding type-1-fimbriated E. coli, and after repeated washings, bound bacteria were allowed to multiply into bacterial colonies by placing the membrane on a solid nutrient substratum. About one major and eight minor glycoproteins, some of which also were detected by Con A, selectively induced colony formation in a mannose-inhibitable fashion. Binding of [35S]methionine metabolically labeled E. coli to PVDF membranes produced a virtually identical binding pattern, demonstrating further the accuracy of this self-enhancing detection method which is rapid, simple, and sensitive and avoids radioisotopes.
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| 11. |
- Karlsson, Anna, 1967, et al.
(author)
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Escherichia coli-induced activation of neutrophil NADPH-oxidase: lipopolysaccharide and formylated peptides act synergistically to induce release of reactive oxygen metabolites.
- 1995
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In: Infection and immunity. - 0019-9567. ; 63:12, s. 4606-12
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Journal article (peer-reviewed)abstract
- The prevailing view of neutrophil NADPH-oxidase activation during interaction with bacteria is that the production of toxic oxygen metabolites should be directed into the phagosome containing the engulfed prey. However, in this report we show that a common Escherichia coli strain, HB101, may induce a release of neutrophil oxygen metabolites to the extracellular milieu. This phenomenon is dependent on three factors: (i) the mobilization (upregulation) of neutrophil secretory vesicles prior to interaction with the bacteria, (ii) soluble bacterial factors binding to the formylmethionyl-leucyl-phenylalanine receptor and tentatively identified as formylated peptides, and (iii) a bacterium-associated priming factor identified as lipopolysaccharide.
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| 12. |
- Strömberg, Niklas, 1974, et al.
(author)
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A fluorescence ratiometric detection scheme for ammonium ions based on the solvent sensitive dye MC 540
- 2003
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In: Sensors and Actuators B-Chemical. ; 90:1-3, s. 308-318
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Journal article (peer-reviewed)abstract
- Principles of wavelength ratiometric evaluation of fluorescence have been extensively used to cancel out and reference sensor response not associated with the analyte. Main limitations of this technique include wavelength ratiometric properties inherent only to a restricted number of solute specific fluorescent dyes. This study presents a dual-excitation/dual-emission ratiometric detection scheme applied on a two-phase coextraction based fluorosensor. Rather than utilizing spectral shifts associated with various complexation and acid-base equilibria of solute specific indicators, we made use of the fluorescence shift induced by the phase transfer of the solvent sensitive dye merocyanine 540 (MC 540) upon ammonium-nonactin coextraction in a hydrogel-ether emulsion. The two-phase ratiometric fluorosensor was exposed to conditions frequently reported to alter performance of fluorescence based optical sensors. Sensor response was unaffected by O-2 concentrations, and signals caused by variations in excitation light intensity and pH were found more or less completely eliminated by the ratiometric procedure. Selectivity towards NH4+ and possible interferences from K+ were more accurately evaluated using the dual-excitation/dual-emission ratio, compared to a single-excitation/single-eniission fluorescence scheme. It was not possible to eliminate artifacts associated with fluctuations in temperature, effective MC 540 concentrations and sample ionic strength by the ratiometric reference scheme, most likely due to monomer-dimer complexation of the indicator dye and the formation of larger aggregates at concentrations exceeding the critical salt concentration of MC 540. Principles described for a two-phase ratiometric detection procedure associated with solvent sensitive dyes rather than solute specific fluorescent dyes may provide a powerful tool for direct solute detection. Thus, the limited versatility of wavelength ratiometric fluorescence detection to specially designed compounds with wavelength ratiometric properties directly linked to interactions with the analyte, may be overcome. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 13. |
- Strömberg, Niklas, 1974, et al.
(author)
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A high throughput optical system for imaging optodes
- 2009
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In: Sensors and Actuators B-Chemical. - : Elsevier BV. - 0925-4005. ; 140:2, s. 418-425
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Journal article (peer-reviewed)abstract
- The objective of this study was to design a high throughput macro imaging system for intensity ratio based optodes, which facilitate both extensive replication and large number of samples to fulfill the statistical requirements for understanding natural processes occurring over extended time. The suggested system accommodates up to 24 sample cells with a field of view of 35 mm or 12 sample cells and 12 calibration cells for a seamless replacement of the optodes to follow processes that last longer than the optode lifetime. The individual components such as sample turrets, LED light sources, filters and lens designs are tested and discussed in detail. Positioning and alignment of an adjacent cell is completed within 6 s with an accuracy of five pixels. The acceleration profile for the sample turret is software controlled, which makes it possible to study e.g. sediments with overlaying water without effects from re-suspension. Calibration is performed by simultaneous filling of all the flow-cells with calibration solution and thereafter a sample run is executed. Thus, the effort required for calibration is the same regardless of the number of sample cells used. The system is automated and controlled through Matlab (Mathworks Inc), which is also is used for post processing of the images. The system was designed for an environmental application where more than 2000 individual images were collected and calibrated to yield 360 sample images.
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| 14. |
- Strömberg, Niklas, 1974, et al.
(author)
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Ammonium selective fluorosensor based on the principles of coextraction
- 2001
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In: Analytica Chimica Acta. ; 443:2, s. 215-225
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Journal article (peer-reviewed)abstract
- The overall objective of this study was to develop an optical fluorosensor (optode) for real-time measurements of ammonium concentrations in natural liquid samples. An NH4+ optode that can be used at such conditions should be analyte specific and independent of ionic strength and pH within a range normally found in such samples (pH 6-8; I-tot 0-700 mM). Additional desired sensor feature is a short response time (preferably minutes or less). This work presents an NH4+ fluorosensor that utilizes similar principles previously described for a K+ selective fluorosensor, i.e. coextraction of a nonactin- ammonium complex and a solvatochromic dye in a hydrogel-ether emulsion. The sensor was tested for its selectivity for ammonium ions compared to other solutes from which interferences frequently have been reported, e.g. K+ and H+. Furthermore, sensor performance at different ionic strengths (I) was evaluated. The ammonium fluorosensor was found to be (i) analyte specific with a selectivity coefficient (K- NH4+.K+(opt)) of 7 x 10(-2), i.e. sensor membranes are about twice as selective to ammonium relative potassium compared to previous studies of electrochemical sensors; (ii) pH independent within the interval 6.0-7.8; (iii) dependent on ionic strength within the interval 100-700 mM, with optimal performance at lowest I-tot evaluated (100 mm); (iv) has a response time of less than 4 min; (v) has the ability to reversibly sense NH4+ even at muM levels. Sensor dynamic range was estimated as 10 muM-100 mM NH4+ in a sample matrix with ionic strength of 100 mM. Construction, configuration and composition of sensor membranes make the ammonium fluorosensor several times reusable, with a sensor shelf life time of at least 8 months. (C) 2001 Elsevier Science B.V. All rights reserved.
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| 15. |
- Strömberg, Niklas, 1974, et al.
(author)
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An imaging pH optode for cell studies based on covalent attachment of 8-hydroxypyrene-1,3,6-trisulfonate to amino cellulose acetate films
- 2009
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In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670. ; 636:1, s. 89-94
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Journal article (peer-reviewed)abstract
- The objective of this study was to create a thin film optode for fast pH measurements that meets the requirements for imaging pi-l-responses from cells as well as for a future hybrid design for detection of multiple analytes Simultaneously. The sensor is based oil the covalent attachment of 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) to a film forming cellulose acetate material through a sulfonamide linkage. The synthesis routes of the cellulose material and regio-specific covalent attachment of the dye are described in detail. The sensor was sterilized in two different ways and showed excellent biocompatibility with Chinese hamster ovary cells. Imprints from cells and Rill thin cell extensions were visualized when altering pH of the Surrounding Solution. The sensor was tested together with time-dependent sigmoidal calibrations giving pH determinations with an exceptional precision and accuracy during measurement within pH 6-8. The precision of the optode, calculated as pooled S.D. (n = 8) according to IUPAC recommendations between pH 6.641 and 7.742 was 0.0029, The accuracy was significantly better than the electrode used as reference during the measurements. The response time (0-95%) was 100s between pH 6.641 and 7.742 and the reverse response (95-0%) was 80s. The sensor shows great potential for extra-cellular pH determination over time during cell growth and pharmacological exposure. (C) 2009 Elsevier B.V. All rights reserved.
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| 16. |
- Strömberg, Niklas, 1974, et al.
(author)
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Assessing an imaging ammonium sensor using time correlated pixel-by-pixel calibration
- 2005
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In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670. ; 550:1-2, s. 61-68
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Journal article (peer-reviewed)abstract
- In this study, a ratiometric imaging ammonium sensor (optode) and a novel calibration technique for imaging optodes were developed, tested and thoroughly evaluated. The overall sensing scheme is based on ammonium coextraction together with a solvent sensitive dye in a hydrogelether emulsion. Quantification of ammonium during 10 days of experiments was made through an image ratio (excitation:emission/excitation:emission; 572 nm:592 nm/520 nm:572 nm ) coupled to the calibration technique i.e. time correlated pixel-by-pixel calibration (TCPC). Sensor performance was validated according to International Union of Pure and Applied Chemistry (IUPAC) recommendations for within-laboratory requirements of reproducibility, and compared with the more frequently used approach of image pixel calibration. Using the TCPC protocol; a limit of detection (LOD) of 1.2 ± 0.2 × 10−6 M was calculated. The preliminary estimate of precision at 200 × 10−6 M, using relative standard deviation (R.S.D.) as a measure, was 5.2% over the 10-day period. The within-batch repeatability was 2.3% (R.S.D.) at 200 × 10−6 M. A linear fit of the data compared the drift over time for the various calibration techniques. Without time correlation, the ratiometric pixel-by-pixel calibrated signal drifted significantly over time. The drift was more or less completely removed using the TCPC protocol. The image resolution, experimentally determined at the distance applied (3 × 10−1 m) by the 1090% edge-response approach, was 210 × 10−6 m. Imaging concentrations and diffusive transport of ammonium in soil during dissolution of a fertilizer stick was given as an example of a versatile sensor application.
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| 17. |
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| 18. |
- Strömberg, Niklas, 1974
(author)
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Determination of ammonium turnover and flow patterns close to roots using Imaging optodes
- 2008
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In: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 42:5, s. 1630-1637
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Journal article (peer-reviewed)abstract
- The physical effect of nitrogen upon plants has been studied thoroughly, however, direct studies of nitrogen turnover close to roots have been limited by analytical techniques with low spatial and temporal resolution. Thus, little is known about differences in turnover taking place along and between intact root structures over time as well as how root arrangement, root cell type, plant age, microbial activity, and the dark/light cycle influence uptake and supply of nutrients to root structures. In this study an imaging (planar) optode was used to quantify ammonium over time close to an intact root system of a large fruit bearing tomato plant (Lycopersicon esculentum). Images throughout the experiment made it possible to define the ammonium depletion zone and active turnover potential as well as determine turnover rate and flow patterns around the root system over time. The results indicated that ammonium uptake for tomato plants proceeds over the entire root structure but transverse thin peripheral roots are about twice as efficient as the main root and that the uptake process might influence nutrient availability. The flow patterns close to the root structure revealed that apical regions seem to have a central role in ammonium acquisition.
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| 19. |
- Strömberg, Niklas, 1974
(author)
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Imaging Optodes
- 2006
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Doctoral thesis (other academic/artistic)
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| 20. |
- Strömberg, Niklas, 1974, et al.
(author)
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Time correlated pixel-by-pixel calibration for quantification and signal quality control during solute imaging
- 2006
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In: Sensors and Actuators B-Chemical. - : Elsevier BV. - 0925-4005. ; 115:1, s. 263-269
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Journal article (peer-reviewed)abstract
- Analytical protocols for normalization of artifacts and signal quality control are crucial in the design of intensity-based imaging optodes. In this study, we demonstrate how the time correlated pixel-by-pixel calibration (TCPC) technique could be used to predict analytical sensitivity, limit of detection (LOD) and determination of signal variation (relative standard deviation, R.S.D.) at a pixel level throughout measurements without separate tests. In addition, LOD from the TCPC protocol was used to define the operational lifetime of the sensor. The technique was tested on a recently developed imaging ammonium optode. The predicted parameters using TCPC agreed well with the determinations of the parameters using standard analytical protocols. Predicted limit of detection was 0.7 x 10(-6) M compared to 1.3 x 10(-6) M determined through a separate LOD determination. The operational lifetime of the optode was 280 h compared to the actual value of 286 h. When exposed to a soil matrix the operational lifetime was significantly reduced to 128 h. The decrease in sensor performance was efficiently tracked by all the statistical parameters, e.g. during a total experimental period of 234 h, the analytical sensitivity changed from 3 x 10(-6) M to 14 x 10(-6) M between 125 x 10(-6) M and 250 x 10(-6) M. The technique is exemplified by a long-term (similar to 10 days) test of a recently developed ammonium fluorosensor, and high-resolution imaging of ammonium concentrations in porous media following dissolution of a fertilizer stick in soil. (c) 2005 Elsevier B.V. All rights reserved.
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| 21. |
- Villanova, Valeria, et al.
(author)
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Unveiling the ecological resilience and industrial potential of Skeletonema marinoi through mixotrophic cultivation in Nordic winter condition
- 2024
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In: Physiologia Plantarum : An International Journal for Plant Biology. - 0031-9317. ; 176:3
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Journal article (peer-reviewed)abstract
- Mixotrophy, the concurrent use of inorganic and organic carbon in the presence of light for microalgal growth, holds ecological and industrial significance. However, it is poorly explored in diatoms, especially in ecologically relevant species like Skeletonema marinoi. This study strategically employed mixotrophic metabolism to optimize the growth of a strain of Skeletonema marinoi (Sm142), which was found potentially important for biomass production on the west coast of Sweden in winter conditions. The aim of this study was to discern the most effective organic carbon sources by closely monitoring microalgal growth through the assessment of optical density, chlorophyll a fluorescence, and biomass concentration. The impact of various carbon sources on the physiology of Sm142 was investigated using photosynthetic and respiratory parameters. The findings revealed that glycerol exhibited the highest potential for enhancing the biomass concentration of Sm142 in a multi-cultivator under the specified experimental conditions, thanks to the increase in respiration activity. Furthermore, the stimulatory effect of glycerol was confirmed at a larger scale using environmental photobioreactors simulating the winter conditions on the west coast of Sweden; it was found comparable to the stimulation by CO2-enriched air versus normal air. These results were the first evidence of the ability of Skeletonema marinoi to perform mixotrophic metabolism during the winter and could explain the ecological success of this diatom on the Swedish west coast. These findings also highlight the importance of both organic and inorganic carbon sources for enhancing biomass productivity in harsh winter conditions.
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