Licentiate theses / Licentiatavhandlingar Institutionen för biologi och miljövetenskap

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    An Analysis of Potential Limitations of in Vitro Cell Lines and in Silico Models in Current Chemical Risk Assessments for Mixtures: A Case Study on Azole Mixtures in Sweden
    (2025) Alvord, Charlotte
    Chemical Risk Assessments (CRAs) are a well-established method to calculate safe levels of chemicals, determined using whole animal testing (in vivo). The European Chemicals Agency (ECHA) are working towards implementing chemical safety using non-animal testing methods, i.e. in vitro acute toxicity testing with fish embryos, fish cell-lines, and in silico mathematical models. In vitro methods are useful, yet they have limitations as fish embryos and cell-lines can exhibit dissimilar metabolism capacity compared to whole, and adult fish. Therefore, we have explored the correlation between in vitro and in vivo test types, where we used azoles as a case study. We studied the toxicokinetic interaction on the detoxification pathway when a fish liver cell-line Poeciliopsis lucida hepatocellular carcinoma (PLHC-1) was exposed to the mixture of an azole and a polycyclic aromatic hydrocarbon (PAH) and created an in silico model to demonstrate the toxicokinetics using the detoxification enzyme Cytochrome P450 1 A (CYP1A). In Study I (unpublished), we used Clotrimazole (CLO) and Benzo[a]pyrene (BaP) in our chemical mixture. This resulted in a 7.3-fold increase in CYP1A activity after a 24-hour exposure with mixture of 5nM BaP and 5µM CLO, and a 6.9-fold increase after 36-hour exposure with the mixture of10 nM BaP and 5µM CLO. This indicates a toxicokinetic interaction and inhibition of CLO on the biotransformation of BaP. In Study 2 (Paper I), we created a mathematical bottom-up model for a synergistic mixture effect, with CYP1A activity data of the mixture of the azole Nocodazole (NOC) and the PAH β-naphthoflavone (BNF). The model uses ordinary differential equations (ODEs) to describe the toxicokinetic pathway, and interaction. In Study 3 (Paper II), we show a moderate correlation between embryonic in vitro and in vivo LC50 values and that although detected azole concentrations indicate a risk in Sewage Treatment Plant (STP) effluent and surface water, their concentrations are well below the concentrations seen to have synergistic effects seen in fish cell-line in vitro studies
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    Wood-Living Beetle Species and Communities in Swedish Forestry: Some Lessons for Conservation
    (2019) Gran, Oskar
    The papers in this thesis examine the diversity of wood-living beetles, a highly diverse group of conservation concern, in the context of southern Swedish forestry and forest management. Since the 19th century, industrial forestry and abandonment of traditional management has led to substantial changes in forest structure and characteristics in the region, with likely detrimental effects for many wood-living beetles. At the same time, management interventions such as different forms of thinning could benefit the group, by creating sun-exposed dead wood which is preferred by several species. In the first paper, an experimental set-up evaluated the 10-year effect of conservation-oriented thinning in oak-dominated (Quercus spp.) mixed forests. We documented a 33% increase in the number of woodliving beetle species associated with oaks, compared to unthinned reference stands. The second paper compared the wood-living beetle fauna of pre-commercially thinned Norway spruce (Picea abies) production forests with that of nearby unthinned woodland key habitats. Overall, the diversity of all wood-living species combined was similar, but lower for some groups, including red listed species, in thinned stands. The results indicate that conservation-oriented thinning can be an effective method of favoring this important organism group in oak-dominated forests over longer periods. In managed spruce forests, pre-commercial thinning may benefit some species but not primarily those of conservation concern.