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Understanding the link between the gut microbiota, diet and the enteric nervous system is of significant importance in the prevention of gastrointestinal disorders. The aim of the study was to answer two questions: Firstly, is butyrate able to stimulate the luminal release of serotonin? Secondly, in which parts of the gastrointestinal tract does this possibly occur? These questions are of interest, due to the importance of the serotonergic signalling in the enteric nervous system. We created a luminal perfusion system to investigate the effect of butyrate in the gastrointestinal tract of male Wistar rats (500-550g). We isolated the stomach and 4 cm long segments of the duodenum, jejunum and colon. To our knowledge this form of physiological ex vivo studies investigating the entire gastrointestinal tract have not been done previously. The isolated stomach and the isolated intestinal segments were luminally perfused with 100 mM butyrate for 10 min respectively 45 min. The tissues were homogenized after the luminal perfusion. Serotonin and its main metabolite 5-hydroxyindoleacetic acid (5-HIAA) were assayed using commercial ELISA kits. Our results showed that butyrate significantly stimulates the release of 5-HIAA in the stomach, duodenum, jejunum and colon. Butyrate seems also to have a positive trend-effect on the release of serotonin itself in the stomach, duodenum, jejunum and colon. Although, there is a future potential for preventing gastrointestinal disorders with the help of diet and gut microbiota, the possible clinical significance of our results should be considered carefully.

Colorectal cancer is one of the most common cancers in the world, and in 2020 it was the cause of nearly 1 million deaths. A major reason for the high death rate is treatment resistance; eventually, almost all colorectal cancer patients with metastatic disease stop responding to chemotherapy. The problem of treatment resistance is not specific to this type of cancer, but it is a widespread issue for all cancer treatments. Chemotherapy resistance is the sum of several cellular and non-cellular factors that together enable sustained cell growth despite the treatment. The non-cellular factors are related to the tumor microenvironment, whereas the cellular factors are related to changes in gene expression, which facilitate e.g. the repair of drug-induced damage or lead to changes in drug metabolism. Lately, researchers have turned their interest to translational control in chemotherapy resistance. This is because translational control plays a major role in stress adaptation. During cellular stress, global translation rates are reduced and those messenger RNAs that are most important for cell survival are translated efficiently. Moreover, translation is fine-tuned by transfer RNA (tRNA) modifications. These modifications are chemical groups that are added to the ribose and the nucleobase of the tRNA molecule, and they affect all aspects of tRNA function, ranging from the structure and stability of the molecule to reading frame maintenance and rate of translation. tRNA modifications are dynamic and change in response to the cellular state, thus facilitating adaptation by translational control. Given the major role of translational control and tRNA modifications in cellular stress responses, their role in the chemotherapy response and adaptation should be thoroughly investigated. The aim of this thesis was to study how chemotherapy affects translation and tRNA modifications in a colon adenocarcinoma model. The cell lines SW480 (from a primary colorectal tumor) and SW620 (from a metastasis) were treated with 5-fluorouracil, oxaliplatin, and leucovorin (FOLFOX), a common combination of chemotherapeutics used in colorectal cancer treatment. The cells were subjected to long-term cyclic treatment as well as 24 h pulse treatment. Chemotherapy resistant cell lines were established by increasing the concentration of FOLFOX for each round of treatment. The effect on translation was studied by polysome profiling, which revealed that FOLFOX treatment causes immediate translational stress, as evidenced by the “shoulders” in the polysomal fractions in the profiles of the pulse treated cells. We hypothesized that these shoulders represent halfmers, polyribosomes without the large subunit. No difference was observed between the long-term treated cells and controls, possibly indicating that the cells had adapted to FOLFOX. The resistant cells exhibited slightly reduced translational activity, which might be due to altered function of ribosomes following the exposure to 5-fluorouracil. Changes in tRNA modification levels were quantified by liquid chromatography mass spectrometry. Several anticodon loop modifications exhibited altered levels after the pulse treatment. In addition, 5-FUrd, a metabolite of 5-fluorouracil, was incorporated into the tRNA. The long-term treated or resistant cells exhibited no differences in the modification levels. In conclusion, this study provided insights on the immediate effects of FOLFOX treatment on translation. This constitutes the first step towards understanding how RNA-based regulatory mechanisms may contribute to the effect and possible resistance to chemotherapy.

Microglia, the resident immune cells of the central nervous system, react to inflammatory stimuli in the brain in a variety of ways. These include migrating to the site of damage and releasing pro- and anti-inflammatory factors. Previous research indicates that these microglial functions require extensive intracellular calcium signaling. Microglial overactivation can exacerbate neuronal damage, especially in cases of chronic inflammation. The ability to modulate the microglial response to damage would therefore be of great clinical relevance. The endoplasmic reticulum (ER) acts as the cell’s main calcium store and regulates cellular calcium levels primarily through the activity of ryanodine receptors (RYR), inositol-triphosphate receptors (IP3R), and the sarco-endoplasmic reticulum calcium ATPase (SERCA) pump. Calcium depletion from the ER is associated with cellular stress and microglial reactivity and therefore the ER may be an important target for modulating the microglial reactive response. The aim of this study is to show whether ER calcium depletion in a microglial cell line causes changes in protein expression, cellular infiltration, and the release of key pro-inflammatory factors. Drugs that block the pumping of calcium from the cytosol via the SERCA pump, such as thapsigargin, effectively induce a state of calcium depletion in the ER. In the present study, treatment with the SERCA pump inhibitor thapsigargin was found to increase SERCA2 expression in BV2, but not SV40, microglial cell lines. Treatment of microglia with thapsigargin was associated with large increases in the release of pro-inflammatory factors IL-6 and TNF-alpha but had no effect on microglial migration.

Spinal cord injury (SCI) in human patients is the most expensive clinical condition worldwide, restricting individuals’ ability to manage with daily-life activities independently. With very limited available treatment possibilities, the understanding and validating of regenerative mechanisms and treatment options in animal models is crucial for their translation to clinical practice. The majority of SCIs in human patients are contusive in the cervical level of the spinal cord. However, thoracic injury rodent model is more commonly studied, with only recent studies working with cervical contusion injury model. Chondroitin sulphate proteoglycans (CSPGs), and especially their CS chains, are thought to be the major inhibitory structures for neurite regeneration after SCI. However, current research has led to a new idea that the inhibitory effect of CS chains can be reversed to regeneration enhancing by heparin-binding growth-associated molecule (HB-GAM). This endogenously secreted molecule is highly up-regulated in the central nervous system (CNS) during postnatal development, but in the adult CNS the expression is down-regulated. This suggests that postnatal-level concentrations might be needed for inducing neurite regeneration in adult CNS. In this study, HB-GAM treatment was tested on both cervical hemicontusion and hemisection injury models. Here we show that repeated intrathecal injections of HB-GAM were sufficient to increase grey matter myelin optical density in mouse hemicontusion injury model, and partly induce functional recovery in hemisection model. Obtained anatomical evidence suggests that enhanced myelination is potentially involved in the repair mechanism of HB-GAM. The connection between HB-GAM treatment and functional recovery, and also other mechanisms of HB-GAM-induced regeneration need further exploration. In broader perspective, the results are promising for translation of a novel treatment approach to clinical use.

After decades of lull, the use of psychedelics as therapeutical agents has regained both scientific and public attention. The so-called classical psychedelics are currently studied in the treatment of multiple psychiatric conditions, including addiction. The current understanding implies that psychedelics mediate their subjective effects through serotonergic 5-HT2A receptor binding. The activation of the receptor also leads to increases in brainderived neurotrophic factor (BDNF) expression, a critical part of neuroplasticity mechanisms. At a behavioral level, facilitated neuroplasticity can be observed for example as quicker learning. Because addiction often involves associative learning between the pleasure produced by the drug use and the environmental cues, learning away from these associations could help to prevent relapses and enhance recovery. In this study we aimed to assess LSD’s effect on BDNF levels in amygdalar and cortical regions, and their connection to extinction learning in fear and conditioned place preference paradigms. To evaluate time window for enhanced neuroplasticity, we chose two time points for BDNF level measurement, 24 and 48 h after the LSD injections. In addition, we chose both male and female mice for behavioral experiments to study possible differences between the sexes. We did not observe statistically significant differences between the treatment groups in BDNF levels or behavioral experiments after the single LSD injections. Despite that, this study provides perspectives for improving the experimental setups, as well as helps to evaluate still unanswered questions around the connection between psychedelics and neuroplasticity.

Enhancement of soil carbon sink has large potential to mitigate climate change. Earlier studies have suggested that improved management practices could promote climate change mitigation and improve soil fertility. To find out if the carbon sink of a clay soil under improved grassland management in Southern Finland can be enhanced by increasing mowing height at harvest, an experiment was set up with two different mowing heights (6 and 15 cm). Net ecosystem carbon exchange, based on total ecosystem respiration and photosynthetic capacity were monitored with chamber methods during three growing seasons from 2019 to 2021. Also, plant biomass, leaf area index, soil temperature, soil pH, soil water retention capacity, and soil grain size distribution were studied at both mowing height treatments. In this study, negative value is the CO2 flux from the atmosphere to the ecosystem and positive value is the CO2 flux from the ecosystem to the atmosphere. Negative NEE means that the ecosystem gains C when the absolute value of GPP is greater than TER and vice versa. The higher mowing height increased CO2 uptake by plants and caused more negative NEE for the higher mowing height after the grass was harvested. These results indicate that higher mowing height might be better for mitigating climate change. However, mowing height did not have a significant effect on biomass, LAI, TER or soil properties in the experiment. Short lasting and non-existent differences between mowing heights are probably explained by more pronounced compensation growth reaction at the lower mowing height as growth conditions were otherwise similar except for mowing height treatment at both treatments. More frequent measurements, especially after the harvest, could better reveal the dynamics of grass height differences and its effects on GHGs. Better detection of the effect of mowing height on the carbon balance would require even more regular and continuous measurements after harvesting and fertilization in different soil types with experimental setups such as applied in this study.

Improving land management to mitigate climate change is important, especially in agriculture on soils with high organic content. Many studies have found evidence that increasing diversity can help to improve plant biomass production and soil carbon storage. This is attributed to complementarity which consists of more efficient resource use due to niche differences and facilitative interactions. For the total climate impact, the effect of greenhouse gas emissions from the soil needs to be considered. To find out if adding more species to a grass mixture could have similar benefits in boreal zone grass cultivation in Finland, an experiment was set up with four different species mixtures, and three levels of species richness were established under a nurse crop. It was additionally of interest if these effects can counter the emissions of cultivation on organic soils. Biomass samples were collected both before the nurse crop was removed and at the end of the growing season. Both species richness and Shannon diversity index were considered as explanatory factors. Carbon exchange, divided into respiration and photosynthetic capacity, as well as nitrous oxide and methane fluxes, were monitored monthly. There was no strong evidence that species richness affects biomass or greenhouse gas fluxes during the first year. The effect of species richness on the biomass was clearer when the diversity index was considered. These results were significant when the lowest biomass values were excluded from the analysis, probably because complementary resource use needs enough biomass to have an effect. The differences in carbon flux measurements may be sensitive to timing within the growing season since the results closest to significant were obtained at the start of the season. At the time, the measurement conditions were good and the nurse crop biomass was small enough not to obscure the effects of grass mixture. When it comes to other greenhouse gases, species richness had most impact on early nitrous oxide emissions, while methane flux probably needs significantly more time for any changes to appear. Overall, the effect of species richness needs to be studied over the full grass cultivation cycle to find out the full effect. Based on current results, increasing species richness may be an option when other methods cannot be used to reduce emissions and improve carbon sink of agriculture.

Anticipated climate change-related shifts in precipitation patterns in Finland may lead to increased off-season rainfall, potentially causing soil waterlogging. Agricultural soils have significant long-term organic carbon stabilization potential due to organic matter interactions with soil minerals, especially iron (hydr)oxides, which play a key role in stabilizing organic matter. However, iron's sensitivity to redox changes during waterlogging can trigger reduction reactions of iron that lead to iron (hydr)oxide dissolution, releasing the carbon stabilized by iron (hydr)oxides. Given the critical role of soil organic carbon in food production and climate change mitigation, it is imperative to expand our understanding of how altered climate conditions affect particularly soil carbon stabilized by soil minerals, across various soil types and depths. The aim of this work was to investigate interactive effects of climate change induced soil moisture changes and cover crop on concentration and fate of dissolved organic carbon (DOC), dissolved iron and total dissolved carbon (DC; including inorganic and organic C) in two different agricultural mineral soils. In greenhouse experiment, the undisturbed soil monoliths of clay and coarse soil were used to investigate if off-season waterlogging could release organic carbon stabilized by soil minerals. Soil monoliths were saturated with water and pore water samples were collected from three different depths prior, during and after water saturation to monitor changes in the concentrations of iron, DOC and DC. Soil moisture and redox potential (Eh) were also monitored throughout the experiment. The effect of soil type, depth and cover crop on DC as well as differences in concentrations with time were statistically tested using linear mixed effects model and Tukey comparison test. The results of this study showed that waterlogging did not lead to reduction of iron and dissolution of iron (hydr)oxides, and consequently, no organic carbon adsorbed on iron (hydr)oxides was released. The presence of a cover crop did not significantly affect concentration of DOC or iron (hydr)oxide dissolution. However, signs of root exudate mineralization were observed under the cover crop treatment in the topsoil. Clay soil exhibited greater DC concentrations compared to coarse soil. Coarse soil showed signs of downward DOC movement during drainage, while clay soil's mid (30 cm) and bottom (50 cm) layers remained less responsive to soil moisture and Eh changes due to its more compact structure. In the future studies it would be important to focus on improving our understanding of the vulnerability of stabilized organic carbon to changing redox conditions in natural soil systems.

Influenza A viruses are pathogens infecting birds and selected mammals. They are responsible for around 500 000 human deaths each year and pose a substantial economic burden to the healthcare system. The most important pathway in influenza virus detection is a retinoic acid-inducible gene I pathway, which recognizes the 5’-triphosphate in viral RNA. Its activation leads to the production of interferons: a group of cytokines important in overcoming viral infection. In order to replicate successfully, viruses had to develop mechanisms to overcome host defences. They include, among others, regulation of interferons and interferon stimulated genes expression. During influenza A virus infection, this function is performed by viral non-structural protein 1 (NS1). The aim of this study was evaluating the effect of NS1 of five different avian influenza strains and one seasonal influenza strain on activation of type I and III interferon gene promoters. The NS1 of seasonal virus H3N2 shown the highest suppression of both interferon I and III promoters, while NS1 originating from avian H9N2 and H7N7 strains had limited effect on interferon promoter activation. NS1 of H5N1/04, H5N1/97 and H7N9 was very effective at suppressing interferon type I promoter, which correlates with the severity of the infection in humans. When it comes to interferon type III promoter, H7N9 was very efficient at the suppression, while NS1 of H5N1/04 had little impact on promoter activation. The study has provided more information on the efficiency of potentially pandemic avian influenza strains at inhibition of interferon response and may be a base for further research. The project was conducted at the Finnish Institute of Health and Welfare.

The general structure of the vertebrate brain is highly conserved. However, a large amount of variation exists in brain size and shape, both regarding the whole brain and its subdivisions. This variation is caused by selection acting on species’ behavioural traits and shaping the evolution of the brain in the same process. It is known that one of the factors affecting vertebrate brain morphology is ecology, including habitat complexity, activity patterns and diet. The effects of diet on brain size have been studied in primates, bats and small mammals, where frugivory in primates and bats and insectivory in small mammals, are linked to larger brains. The effect of diet on brain morphology has not been studied in squamate reptiles (lizards and snakes) and the ecological factors behind size and shape variation are largely unknown in squamates compared to other vertebrates. Squamates show large diversity in diet preference as well as feeding behaviour in general, which makes them a suitable model organism to study brain evolution. Further, squamates have highly developed nasal chemical senses that are important for feeding behaviour. These factors in mind, it would be expected that diet has an effect on squamate brain morphology, and especially the brain regions important for feeding behaviour, such as the olfactory bulbs in the forebrain. To study the effects of diet on squamate brain size and shape, the brains of 51 squamate species were micro-CT scanned and 3D-brain surfaces were generated for each species. The species were categorized into four diet groups: carnivorous, herbivorous, omnivorous and insectivorous. To analyse shape and size change across species and diet groups, 73 landmarks were placed on each 3D-brain surface, covering all brain regions: olfactory bulbs, cerebral hemispheres, telencephalon, diencephalon, midbrain, cerebellum and hindbrain. The results from this study show that diet affects significantly the shape of the whole squamate brain, as well as the size of the telencephalon. Telencephalon size differed significantly between the herbivorous and carnivorous groups. Diet had no significant effect on the other brain subdivisions studied here, including the olfactory bulbs. Diet is a large part of a species’ ecology and it is very complex behaviour involving several senses and brain regions, which could explain the results obtained from this study. The results from this study are preliminary, but they indicate that diet could be one of the factors affecting brain morphology in squamates. In the future, including other factors of feeding behaviour than food choice and analysing the effects of diet on a deeper level, such as including brain regions within the brain and analysing cellular organization, could shed some new light on how diet affects squamate brain morphology.