| 1. |
- Slazak, Blazej, et al.
(författare)
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The involvement of cyclotides in mutual interactions of violets and the two-spotted spider mite
- 2022
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Plants employ different chemicals to protect themselves from herbivory. These defenses may be constitutive or triggered by stress. The chemicals can be toxic, act as repellents, phagosuppressants and/or phago-deterrents. The two-spotted spider mite (Tetranychus urticae) is a generalist arthropod herbivorous pest and its feeding causes extensive damage both to crops and wild plants. Cyclotides are cyclic peptides involved in host-plant defenses. A single Viola sp. can produce more than a hundred cyclotides with different biological activities and roles. The organ and tissue specific cyclotide patterns change over the seasons and/or with environment, but the role of biotic/abiotic stress in shaping them remains unclear. Here, we demonstrate the involvement of cyclotides in mutual interactions between violets and mites. We used immunohistochemistry and mass spectrometry imaging to show the ingested cyclotides in T. urticae and assess the Viola odorata response to mite feeding. Moreover, to assess how mites are affected by feeding on violets, acceptance and reproductive performance was compared between Viola uliginosa, V. odorata and Phaseolus vulgaris. We demonstrate that cyclotides had been taken in by mites feeding on the violets. The ingested peptides were found in contact with epithelial cells of the mite digestive system, in the fecal matter, feces, ovary and eggs. Mites preferred common bean plants (P. vulgaris) to any of the violet species; the latter affected their reproductive performance. The production of particular cyclotides in V. odorata (denoted by molecular weights: 2979, 3001, 3017, 3068, 3084, 3123) was activated by mite feeding and their levels were significantly elevated compared to the control after 5 and 21 days of infestation. Specific cyclotides may affect mites by being indigestible or through direct interaction with cells in the mite digestive tract and reproductive organs. A group of particular peptides in V. odorata appears to be involved in defense response against herbivores.
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| 2. |
- Andrén, Anna, 1970-
(författare)
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Freezing Temperature Flows in Railway Tunnels and its Consequence on the Rock Supporting Structure, the Rock and the Reinforcing Elements
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Water in the surrounding rock mass flows into the tunnel via naturally occurring joints and via cracks caused by the blasting used to excavate the tunnel. The most common method in Sweden to reduce or prevent leakage problems are first and foremost the use of grouting. However, experience shows that despite extensive pre-grouting and supplementary post-grouting, it is difficult to seal the rock mass so that drips and moisture are completely eliminated. Although the water itself causes degradation of the tunnel, the degradation process increases dramatically when the water is exposed to freezing temperatures. Water expands during freezing and due to water migration, which occurs in rock in a similar way as in soil, the ice causes frost shattering of the interface between rock and shotcrete and also to the shotcrete and the rock itself. This can damage the main load-bearing system. The ice formation itself is a maintenance problem, as the tunnels must be kept clear of icicles, ice pillars and ice layers in the tracks or on the roads. One of the main tasks in this research project has been to identify which problems cause the most maintenance work and where and when these problems occur in the tunnel.During the field observations carried out as part of this doctoral study, many problems with water and ice were discovered, all of which contribute to increased maintenance. Many ice problems are directly linked to frost insulated drain mats. Leakage and ice formations occur at the edge of the drains, in mat splices and when brackets for cable racks, handrails or other installations puncture a drain and it has not been properly sealed. In drains covered with shotcrete, frost shattering and cracking in the shotcrete can be a problem. Frost cycles in the tunnel cause the water to freeze and thaw alternately, allowing more water to reach the freezing area due to water migration, resulting in frost shattering of the rock and the shotcrete. If not anchored with bolts, the reinforcing effect and the stability of shotcrete in a tunnel is dependent on the adhesion to the rock surface. It is, therefore, important to take all available measures to ensure good adhesion. Poor adhesion in itself is not a degradation problem, but a void can form in the interface between rock and shotcrete as a result of poor adhesion. If this void is filled with water that cannot drain away, ice pressure can occur in the layer between rock and shotcrete. The ice pressure can cause cracking and degradation of the shotcrete if the pressure exceeds the tensile strength of the adjacent material. In some of the reported fall-outs of rock and shotcrete, an ice layer was discovered between the rock surface and the edges of the remaining shotcrete layer. Therefore, frost shattering is a likely cause of the fall-outs. Many frost cycles combined with water leakage can cause frost shattering. The field measurements conducted as a part of the doctoral study have shown that most frost cycles do not occur closest to the tunnel entrances, but instead about 100 to 200 m into the longer tunnels. The results from the laboratory tests performed as part of the doctoral study showed that the adhesive strength between rock and shotcrete decreased significantly when the test panels were subjected to freeze-thaw cycles. Furthermore, more of the micro seismic events (AE - acoustic emission monitoring) occurred in the test panels that had access to water during freezing. Therefor, maintenance personnel and inspectors should pay particular attention to water leakage in sections that have an increased number of frost cycles, to avoid future problems with frost shattering of rock or shotcrete. In the longer tunnels studied in this work, a greater number of ice formations occurred in the inner parts of the tunnel, than close to the entrances. The rock mass emits heat, which heats up the cold outside air that enters the tunnel. Due to the heat transfer from the rock mass, leakage points located further along the tunnels can remain unfrozen. A leak that is closer to the tunnel entrances in the longer tunnels or a leak in a shorter tunnel are exposed to higher freezing rates. The entire rock mass freezes and the leak ‘freezes dry’, that is, ice forms in the water-bearing fracture, preventing further water leakage.Where and when ice problems occur along a tunnel depends on many factors. Besides the obvious water leakage, the length of frost penetration into the tunnel is the main reason for where and when ice problems occur. The predominant cause of frost penetration in most of the tunnels is the thermally induced airflow. In the longer tunnels, the inclination of the tunnel affects frost penetration the most. The field observations showed that there was a difference in where and when leakage points appear during the year and also in terms of variation in the amount of leakage water. There was also a variation over different years. The conclusions of the field observations are that it is difficult to estimate where the insulated drain mats should be located along a tunnel. Based on experience from this survey, the location of the drains should be determined only after several inspections and especially after a winter period, when the main problems with ice formation occur. Previous perception regarding ice problems have been that ice formation only occurs at the tunnel entrances and in the outer parts of the tunnel. A proposed measure has, therefore, been to cover the first 300 m from each entrance with frost insulated drains to try to completely eliminate the ice problems. However, this is not an effective solution to the problem. The insulation not only prevents the cold from reaching the leakage point, but it also prevents the rock mass from emitting heat that warms up the cold outside air entering the tunnel. Thus, the frost can penetrate further into the tunnel and the problems with ice formation are only moved further into the tunnel. As the amount and location of the frost insulation affects frost penetration, the dimensioning of insulation must, therefore, be carried out in several iterations, where each new distribution of insulation along the tunnel is calculated separately.For the tunnels that have been studied as part of this doctoral study, the following has emerged. The central and southern parts of Sweden have shorter cooling periods and the tunnels are exposed to many temperature fluctuations around 0°C during the winter. The frost does not have time to penetrate as far here as in the tunnels in the northern parts of Sweden. Therefore, more ice problems arise around the entrances of the tunnels in the southern parts of Sweden than for those in the northern parts. For northern parts of Sweden, the problem of growing ice formations in sections near the tunnel entrance usually occurs only during the autumn and spring, but not in winter. The field observations showed that the problems with ice growth and temperature fluctuations around 0°C occur further along the longer tunnels in the northern parts of Sweden. This is because the temperature of the tunnel air is higher due to heat transfer from the rock mass. For shorter tunnels that adopt the same temperatures as the outside air, ice formations can occur along the entire length of the tunnel in the sections that have leakage problems. The Swedish Transport Administration’s regulations are currently being updated and the observations and measurements carried out in this doctoral work are now being used to evaluate new requirements regarding frost penetration in tunnels.
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| 3. |
- Ericson, Mia, 1970, et al.
(författare)
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Different dopamine tone in ethanol high- and low-consuming Wistar rats
- 2020
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Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 2019
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Tidskriftsartikel (refereegranskat)abstract
- - Excessive alcohol use causes considerable morbidity and mortality worldwide. Changes in the mesolimbic dopamine system have been postulated as a neurobiological underpinning of excessive alcohol consumption, and recent research also suggests that the amino acid taurine plays a central role in ethanol-induced dopamine elevation. The aim of this study was to further outline the role of dopamine and taurine in regulating alcohol consumption. In this study, a choice between ethanol (20%) and water was administered to Wistar rats in an intermittent manner (three times/week) for seven consecutive weeks. In vivo microdialysis was used to explore baseline levels as well as ethanol-induced increases of extracellular dopamine and taurine, in the nucleus accumbens (nAc) of Wistar rats voluntarily consuming large or small amounts of ethanol. Basal levels of taurine were also measured in cerebrospinal fluid (CSF) and serum in a subset of rats. Ethanol-induced increases in nAc dopamine and taurine did not differ between alcohol-consuming and naïve rats. However, when categorized based on ethanol intake, rats consuming larger amounts of ethanol exhibited a lower dopamine tone in the nucleus accumbens and responded to ethanol with a slower elevation of extracellular taurine levels, as compared with low-consuming animals. Basal levels of taurine in nAc, CSF, or serum did not differ between ethanol high- and low-consuming rats. Our data support previous studies claiming an association between low endogenous dopamine levels and excessive alcohol intake. © 2019 Society for the Study of Addiction
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| 4. |
- Morud, Julia, 1984, et al.
(författare)
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Progressive modulation of accumbal neurotransmission and anxiety-like behavior following protracted nicotine withdrawal
- 2018
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Ingår i: Neuropharmacology. - : Elsevier BV. - 0028-3908. ; 128, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- Due to the highly addictive properties of nicotine, a low percentage of users successfully maintain cessation for longer periods of time. This might be linked to neuroadaptations elicited by the drug, and understanding progressive changes in neuronal function might provide critical insight into nicotine addiction. We have previously shown that neurotransmission in the nucleus accumbens (nAc), a key brain region with respect to drug reinforcement and relapse, is suppressed for as long as seven months after a brief period of nicotine treatment. Studies were therefore performed to define the temporal properties of these effects, and to assess behavioral correlates to altered neurotransmission. Ex vivo electrophysiology revealed progressive depression of synaptic efficacy in the nAc of rats previously receiving nicotine. In addition, following three months of nicotine withdrawal, the responses to GABAA receptor modulating drugs were blunted together with downregulation of several GABAA receptor subunits. In correlation to reduced accumbal neurotransmission, a reduced anxiety-like behavior; assessed in the elevated plus-maze and marble burying tests, were identified in animals pre-treated with nicotine. Lastly, to test the causal relationship between suppressed excitability in the nAc and reduced anxiety-like behavior, rats received local administration of diazepam in the nAc while monitoring behavioral effects on the elevated plus-maze. These results show that nicotine produces long-lasting changes in the GABAergic system, which are observed first after extended withdrawal. Our data also suggest that nicotine produces a progressive suppression of accumbal excitability, which could result in behavioral alterations that may have implications for further drug intake. © 2017
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| 5. |
- Slazak, Blazej, et al.
(författare)
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Cyclotide host-defense tailored for species and environments in violets from the Canary Islands
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Cyclotides are cyclic peptides produced by plants. Due to their insecticidal properties, they are thought to be involved in host defense. Violets produce complex mixtures of cyclotides, that are characteristic for each species and variable in different environments. Herein, we utilized mass spectrometry (LC–MS, MALDI-MS), transcriptomics and biological assays to investigate the diversity, differences in cyclotide expression based on species and different environment, and antimicrobial activity of cyclotides found in violets from the Canary Islands. A wide range of different habitats can be found on these islands, from subtropical forests to dry volcano peaks at high altitudes. The islands are inhabited by the endemic Viola palmensis, V. cheiranthifolia, V. anagae and the common V. odorata. The number of cyclotides produced by a given species varied in plants from different environments. The highest diversity was noted in V. anagae which resides in subtropical forest and the lowest in V. cheiranthifolia from the Teide volcano. Transcriptome sequencing and LC–MS were used to identify 23 cyclotide sequences from V. anagae. Cyclotide extracts exhibited antifungal activities with the lowest minimal inhibitory concentrations noted for V. anagae (15.62 μg/ml against Fusarium culmorum). The analysis of the relative abundance of 30 selected cyclotides revealed patterns characteristic to both species and populations, which can be the result of genetic variability or environmental conditions in different habitats. The current study exemplifies how plants tailor their host defense peptides for various habitats, and the usefulness of cyclotides as markers for chemosystematics.
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| 6. |
- Slazak, Blazej, et al.
(författare)
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The Influence of Plant Stress Hormones and Biotic Elicitors on Cyclotide Production in Viola uliginosa Cell Suspension Cultures
- 2022
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Ingår i: PLANTS. - : MDPI. - 2223-7747. ; 11:14
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Tidskriftsartikel (refereegranskat)abstract
- Cyclotides are macrocycle peptides produced by plants from several families, including Violaceae. These compounds have the potential for applications in medicine, bioengineering and crop protection thanks to their multiple biological activities. In most cases, cyclotides are extracted from plant material. Plant cell culture provides a viable and sustainable form of plant biomass production Cyclotides are host defense peptides. The aim of the current study was to test whether different plant stress hormones and biological elicitors have effects on cyclotide production in Viola uliginosa suspension cultures. Different concentrations of jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA) and neutralized pathogens were tested. The cyclotide production was assessed using MALDI-MS. Five major peptides produced by V. uliginosa cultures were chosen for analysis, of which one was sequenced de novo. The treatments had little influence on the suspension's growth, with the exception of 100 mu M SA, which enhanced the biomass increase, and 100 mu M ABA, which was toxic. Significant increases in the production of three cyclotides (viul M, cyO13 and cyO3) were observed in suspensions primed with JA (50 mu M, 100 mu M, 200 mu M) after 14 days of culturing. Biotic elicitors had no observable effect on cyclotide production. The current study indicates that some cyclotides in V. uliginosa are triggered in response to JA. The stress plant hormones can be used to enhance plant cell culture-based production systems.
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| 7. |
- Ulenius, Lisa, 1987, et al.
(författare)
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Sub-chronic taurine administration induces behavioral sensitization but does not influence ethanol-induced dopamine release in the nucleus accumbens
- 2020
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Ingår i: Pharmacology Biochemistry and Behavior. - : Elsevier BV. - 0091-3057 .- 1873-5177. ; 188
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier Inc. Preclinical studies have shown that the amino acid taurine is of importance for the dopamine elevating properties of ethanol. Taurine intake has escalated over the last decade due to increased consumption of taurine-containing energy drinks and dietary supplements. Whether long-term intake of large amounts of taurine induces adaptations affecting ethanol-induced dopamine elevation is not clear. Thus the aim of the present studies was to explore the impact of repeated administration of large amounts of taurine on ethanol-induced behavior and dopamine neurotransmission. Repeated daily systemic administration of taurine increased taurine-induced locomotor activity and rearing. Acute administration of taurine and ethanol in naïve animals produced an additive effect on extracellular taurine but no alteration of the ethanol-induced dopamine elevation, as measured by in vivo microdialysis. Sub-chronic administration of taurine did not modify the taurine- or dopamine-elevating properties of ethanol. Daily taurine treatment also failed to change the mRNA expression of the taurine transporter and GABAA- and glycine-receptor subunits, as measured by qPCR in nucleus accumbens tissue. We conclude that systemic administration of taurine may have long lasting central effects, here displayed as behavioral sensitization. However, repeated daily exposure to taurine does not appear to influence the dopamine elevating properties of ethanol.
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