Browsing by discipline "Physiology and Neuroscience"

This study focused on the spectral sensitivity of two Norwegian lake populations of opossum shrimp (Mysis relicta), with a common implantation history and a temporal separation of about 50 years. Previous findings have indicated a difference in the absorption maximum (λmax) between sea and lake populations of Nordic mysids that have been separated about 9 000 years. Between the population groups, the spectral sensitivity correlates to the Wavelength of Maximal Transmission (WLMT) in the habitats. This may be considered a form of adaptive tuning. It is not known if the species-specific mechanism is based on chromophore shift or opsin modification or a combination of both, neither is the timescale of the adaption well understood. The intent was to determine λmax of both populations, what chromophore(s) they use and possible variations of the opsin gene. By comparison to spectrometric data of the habitats, the study aimed to broaden the insight into the mentioned unknowns. The light conditions of the lakes were determined by spectrometry down to depths of three and five meters. As predicted a positive, lake-bound correlation between the attenuation coefficient (k) and WMLT was found. Single-rhabdom microspectrophotometry (MSP) was used to determine λmax of the visual pigment in situ. Absorbance spectra were analysed by manual fitting to mathematical pigment templates and by script-based automation. Neither the chromophore nor differences in λmax could be determined, due to a small sample size that limited the statistical power of the results. The opsin genes from both populations were sequenced. No differences expected to have an effect on spectral sensitivity were found. Spectral tuning could not be demonstrated to have occurred in the populations due to the limited sample size. Nor did the results give support for any new findings on the mechanism or the time scale of spectral tuning among mysids. To answer the proposed questions of the study, additional sampling of both populations is needed.

The consumption of omega (n-) 3 polyunsaturated fatty acids (PUFA) from fish has been associated with lower rates of cardiovascular diseases with one mechanism being lowering LDL cholesterol levels in blood. When incorporated into LDL particle n-3 PUFAs can modify the lipid composition and reduce atherogenicity of the particle, e.g. by influencing inflammatory processes. The effects of n-3 PUFA of plant origin are less studied. This study investigated the effects of Camelina sativa oil (CSO), a rich source of alpha-linolenic acid (ALA), on lipid species of human LDL including phosphatidylcholines (PC), lysophosphatidylcholines (LPC), sphingomyelin (SM), triacylglycerols (TAG) and cholesterol esters (CE). A total of 38 subjects with a history of impaired fasting glucose, were randomly divided into two groups; CSO (ALA 10 g/day) and the control group (limited fish and ALA intake) for 12 weeks. Blood samples were collected from the subjects at the beginning and at the end of the experiment after 12 weeks. LDL particles were isolated from blood and the lipids were analyzed by mass spectrometry. The CSO affected more the LDL core lipids (TAG and CE) than lipid species of the shell (PC, LPC, SM). CSO is high in ALA and linoleic acid (LA). Thus, the diet reduced mole fractions of lipid species containing saturated acyl chains while acyl chains in the core lipids with ALA, LA and EPA, that is formed in the body from ALA, were increased. Based on the results, having CSO in the diet changed the LDL particle lipid composition in a favorable direction for cardiovascular health.

Classical and rapid-acting antidepressant drugs have been shown to reinstate juvenile-like plasticity in the adult brain, allowing mature neuronal networks to rewire in an environmentally-driven/activity-dependent process. Indeed, antidepressant drugs gradually increase expression of brain-derived neurotrophic factor (BDNF) and can rapidly activate signaling of its high-affinity receptor TRKB. However, the exact mechanism of action underlying drug-induced restoration of juvenile-like plasticity remains poorly understood. In this study we first characterized acute effects of classical and rapid-acting antidepressant drugs on the interaction between TRKB and postsynaptic density (PSD) proteins PSD-93 and PSD-95 in vitro. PSD proteins constitute the core of synaptic complexes by anchoring receptors, ion channels, adhesion proteins and various signaling molecules, and are also involved in protein transport and cell surface localization. PSD proteins have in common their role as key regulators of synaptic structure and function, although PSD-93 and PSD-95 are associated with different functions during development and have opposing effects on the state of plasticity in individual synapses and neurons. Secondly, we investigated changes in mobility of TRKB in dendritic structures in response to treatment with antidepressant drugs in vitro. We found that antidepressant drugs decrease anchoring of TRKB with PSD-93 and PSD-95, and can rapidly increase TRKB turnover in dendritic spines. Our results contribute to the mechanistic model explaining drug-induced restoration of juvenile-like neuronal plasticity, and may provide a common basis for the effects of antidepressant drugs.

Visual working memory (VWM) maintains information for future usage. Several studies show that the cortical oscillations in the γ-frequency band (from 30 to 120 Hz) are modulated by the VWM performance. However, less is known about the cortical sources underlying the modulation of these oscillations in VWM. To address this question, we recorded human neuronal activity with magneto- and electroencephalography (M/EEG) during a delayed-matching-to-sample VWM task with three different task conditions, within which participants were instructed to focus on different object features in turn. In addition, anatomical data was acquired with magnetic resonance imaging for source modeling purposes. We then estimated the cortical amplitude dynamics across frequencies from three to 90 Hz during the VWM retention period for these three different conditions. We found that the amplitudes of the γ –frequency band oscillations were strengthened in the occipito-temporal cortical areas during the VWM for shapes but not for color or spatial locations. These data suggest that γ –band oscillations are fundamental in VWM, especially for visual stimuli requiring perceptual feature binding. Furthermore, cortical γ –band oscillations were found to be load dependently strengthened in the frontal cortex, where the central executive and attention associated processes are believed to take place. These data support the previous hypotheses stating that γ –band oscillations contribute to the maintenance of object representations in VWM.

The skull represents the most highly diversified and evolutionarily adapted anatomical aspect of metazoans, and its development and evolution have been a major driving force in the expansion of vertebrates. The evolution of skull and lower jaw bones have led to the adaptive radiation of jawed vertebrates, and skull tissues have changed rapidly over time and were finely tuned to meet functional and ecological demands with tremendous precision. Because of the long-lasting interest in conventional animal models, there is no general genetic or developmental model of skull evolution and diversity in vertebrates. Squamate reptiles represent the best model to study those aspects because of their key basal phylogenetic position within amniotes (i.e., mammals, birds, reptiles) and their exceptionally high levels of morphological variation (including their kinetic skulls). In particular, their lower jaw bones display tremendous variation. In order to assess this variation and the ecological and developmental factors connected to it, several methods from different fields of biology have to be used. In this study, morphometric, embryology and developmental approaches are used to investigate the ecological and developmental factors associated with the diversification of lower jaw bones in snakes and lizards. The shape diversity of squamate lower jaw bones was approached in a systematic way, using geometric morphometrics. Embryological methods were used to compare the embryonic stage of available squamate model animals at oviposition and to assess the order of ossification of embryo with earliest developmental stage at oviposition (bearded dragon, Pogona vitticeps). In addition, expression of major conserved candidate genes at different stages of lower jaw development (pharyngeal arches, mesenchyme patterning, ossification) were assessed in this species. The results indicate that the lower jaw bones of snakes versus lizards but also of fossorial squamates versus other habitats are significantly different. Heterochrony was also detected at both early stages (pharyngeal arche development at oviposition) and at the onset of ossification in lizards and snakes. Coherent with that, alterations in the expression pattern of Dlx genes in pharyngeal arches were observed in bearded dragon in comparison to earlier studies with mice, while other conserved markers of skeletogenesis were rather conserved. This analysis of the genotype and phenotype map of the reptilian skull provides some new insights into the development, origin and divergence of vertebrate tissues. The results will establish a good basis for future studies involving comparative developmental biology of bearded dragon. Future studies will offer excellent new opportunities to link craniofacial morphology, genetics/genomics and development to both ecological adaptation and evolutionary biology.

Hypothyroidism affected 337 370 people in Finland in 2019. The hypothalamus-pituitary negative feedback loop is used in the diagnostics of hypothyroidism. TSH, a pituitary hormone, is the most used diagnostic tool with the free thyroxine (T4) in a supporting role. L-T4 has been the main treatment option, since the discovery of peripheral deiodination. Biochemical and clinical euthyroidism is the aim of L-T4 therapy. There are no nationwide official treatment guidelines for hypothyroidism in Finland. The Finnish Endocrine Society has published their recommended guidelines in 2019. Studies have shown that 5–15 % of levothyroxine treated patients continue to report symptoms when they are biochemically euthyroid. The symptoms consist of typical symptoms of hypothyroidism: fatigue, cognitive symptoms, depression, anxiety and weight gain. The molecular basis of the symptoms is not yet known. These symptoms have notbeen studied in Finnish population. The aim of this study was to find out what symptoms levothyroxine treated patients report on Finnish social media support groups and view the current treatment of hypothyroidism and guidelines of treatment. This study was conducted by surveying patient-reported information from social media hypothyroidism related support groups. The posts were divided into two groups: hypothyreotic and athyreotic. The biochemical data and symptoms were collected from 137 posts in the athyreotic group and 191 in the hypothyreotic group. Only posts with TSH under or within the refence range and free T4 within the reference range wereincluded in the study. The results show that patients reported symptoms in 74 % of the posts viewed. 81 % of patients reported symptoms in the hypothyroidism group and 64.2 % in the athyreotic group. The most reported symptom in both groups was fatigue. Symptoms were reported within the normal TSH range (0.5-4 mU/l) and below the normal range (<0.5 mU/l). In asymptomatic patients the median TSH was 0.38 mU/l in the athyreotic group and 0.54 mU/l in the hypothyreotic group. Free T4 seems to be a little higher in the asymptomatic patients in both groups. 16.6-25 % the patients reported that they had had Free T3 measured. Free T3 seem to be higher in relation to free T4 in the athyreotic group that reported having no symptoms. L-T4 is the recommended treatment modality for hypothyroidism. Other options are synthetic combination treatment with L-T4 + L-T3 and desiccated thyroid extract (DTE).This study supports the view that hypothyroidism patients can have symptoms on levothyroxine treatment

Our hearing perception is based on the ability to discriminate mechanical sound waves and to amplify and transduce them into electrical stimuli.This function is based on the complex cellular organization of the cochlea, the hearing organ. The sensory epithelium in the organ of Corti spirals along the cochlear duct in a tonotopic arrangement: every sound frequency elicits the strongest response at allocation along this duct. Sound stimulus is detected by three rows of outer hair cells (OHCs) which amplify- and tone-discriminate the sound stimulus, and by one row of inner hair cells (IHCs), which transduce the mechanical stimulus into electric impulses. Basal regions of the cochlea detect high- frequency sounds and apical regions detect low- frequency sounds. The complexity and sensitivity of the cochlea is linked with its vulnerability to various traumas. Most kinds of damage to the mammalian hair cells is irreversible, because these cells are not capable of regeneration. Hearing impairment has many etiologies. Common to them is that damage is permanent and no pharmacotherapy is available. Hearing impairment is often a disabling condition and it has vast societal consequences. The number of hearing impaired people is constantly increasing and the WHO has estimated that 10% of the world`s population will suffer from disabling hearing loss in 2050. Mesencephalic astrocyte- derived neurotrophic factor (MANF) is an unconventional, ER-resident protein that promotes ER- homeostasis. It has been associated with cytoprotective functions in many neurodegenerative disease- models and shown to promote recovery after ischemic trauma. MANF expression has been previously found in many cell-types in the cochlea, including OHCs and IHCs. Its deficiency in a mouse model led to upregulation of ER-stress markers and a robust, tonotopic base –to apex gradient loss of outer hair cells and severe hearing loss. This study examines the role of MANF in noise-induced trauma in the hair cells of the cochlea. In a conditionally inactivated (Manf -/- cKO) mouse model in the C57BL/6J – background, where Manf has been inactivated from most of the cochlear cells, I studied, if Manf -deficiency sensitizes the cells to noise-induced cell death in two age-groups. I also examined the basic and noise- induced MANF expression, using two mouse- strains, C57BL/6J and CBA/Ca. I also examined OHC stereociliary bundle morphology to find out if noise induces morphological changes in Manf cKO-mice that differ from noise-exposed C57BL/6j wild type mice. This study found that OHCs have a low MANF- expression, whereas in IHCs the expression is strong. MANF is expressed in a base- to apex gradient in the OHCs of the two mouse-strains examined, in a uniform pattern, that correlates with vulnerability, implicating that low levels of MANF predispose basal OHCs to vulnerability. MANF expression in the IHCs was non-gradiental. Noise did not induce upregulation, as was expected, but instead noise induced downregulation of MANF in the basal region of the OHCs by an unknown mechanism in both mouse-strains.This suggests that noise-induced trauma induces ER dyshomeostasis, possibly independent of ER stress response pathways ,unfold protein response (UPR). This study also demonstrates that MANF deficiency sensitizes the OHCs to noise- induced trauma, resulting in more elevated OHC loss and hearing thresholds. This sensitization is mainly caused by a progressive degenerative changes seen in the OHC stereociliary bundles of Manf cKO-mice, and is associated with more severe noise-induced hearing loss. The results of my study suggest that MANF has an important, yet unknown, protective role in noise-induced trauma in OHCs. These results support the possible role of MANF as a therapeutic agent in a noise-induced trauma.

Työssä tutkittiin rasvahappojen kerrostumista itämerennorpan (Phoca hispida botnica) traanissa ja tämän merkitystä rasvahappokoostumukseen perustuvassa ravintokohteiden arvioinnissa. Vertaamalla sisätraanin rasvahappokoostumusta plasman ja maksan rasvahappokoostumuksiin pyrittiin selvittämään siirtyvätkö jotkut tietyt ravinnon rasvahapot toisia tehokkaammin traanin sisäosiin, eli heijastelevatko jotkut sisätraanin rasvahapoista ravinnon rasvahappokoostumusta toisia paremmin. Itämerennorpan traanin eri kerrosten rasvahappokoostumusta verrattiin myös sen tärkeimmän ravintokalan, Itämeren silakan rasvahappokoostumukseen, jotta nähtäisiin minkä kerroksen koostumus muistuttaa eniten ravinnon rasvahappokoostumusta. Vertailun vuoksi työssä tutkittiin myös makeassa vedessä elävän saimaannorpan (Phoca hispida saimensis) traanin ja maksan rasvahappokoostumuksia. Lisäksi määritettiin plasma- ja maksanäytteiden kuljettaman tai lyhytaikaisesti varastoiman varastorasvan määrät. Tutkimuksessa käytettiin Perämerellä ammutuista itämerennorpista kerättyjä traani-, maksa- ja plasmanäytteitä, sekä kuolleina löydetyistä saimaannorpista kerättyjä traani- ja maksanäytteitä. Kudosnäytteiden rasvahappokoostumusten määritys tehtiin analysoimalla niistä valmistettuja rasvahappojen metyyliesteriseoksia kaasukromatografisesti (GC). Lipidiluokkakoostumukset puolestaan määritettiin korkean erotuskyvyn ohutlevykromatografialla (HPTLC). Analyysien tuloksia käsiteltiin tilastollisesti pääkomponenttianalyysin (PCA) ja sen tuloksia ohjatusti luokittelevan menetelmän (SIMCA) avulla, regressioanalyysillä, sekä laskemalla koostumusten euklidisia etäisyyksiä eri näytteiden välillä. Jokaisen yksilön traanille luotiin vertikaalinen rasvahappoprofiili toisiaan nahasta lihakseen seuraavien osanäytteiden rasvahappokoostumuksen perusteella. Itämerennorpan traanin kerrostuneisuutta tutkittiin nyt ensimmäistä kertaa ja sen havaittiin olevan rakenteeltaan kerrostunut, kuten on havaittu myös aiemmin tutkituilla kahdella norpan alalajilla. Aiemmista tutkimustuloksista poiketen keskitraani ei kuitenkaan eronnut rasvahappokoostumukseltaan merkitsevästi muista traanikerroksista. Sisä- ja ulkotraanin väliset rasvahappokoostumuksen erot olivat sen sijaan merkitseviä. Traanikerroksista sisätraani muistutti eniten itämerennorpan tärkeän saalislajin, silakan, rasvahappokoostumusta. Itämerennorpan kudosten rasvahappokoostumus erosi selvästi saimaannorpan kudosten rasvahappokoostumuksista. Näiden kahden alalajin ulkotraanit kuitenkin muistuttivat toisiaan rasvahappokoostumukseltaan sisätraaneja enemmän, mikä viittaa siihen, että niiden ulkotraanin koostumusta säätelevät samankaltaiset lämmönsäätelyyn liittyvät geneettisesti määräytyvät tekijät. Rasvahappokoostumusten alalajikohtaisista eroista huolimatta traanin rasvahappojen kerrostumistapa oli samanlainen molemmilla tutkituista alalajeista. Traanin vertikaaliset rasvahappoprofiilit olivat kuitenkin hyvin yksilöllisiä. Useiden rasvahappojen suhteelliset määrät plasmassa ja sisätraanissa korreloivat tilastollisesti merkitsevästi keskenään. Tämä tulos vahvistaa oletuksen, että viimeaikaisella ravinnolla on vaikutusta erityisesti sisätraanin rasvahappokoostumukseen ja, että sen perusteella voidaan saada tietoa eläimen ravinnosta. On kuitenkin huomattava, että tietyt sisätraanin rasvahapot ilmentävät ravinnon rasvahappokoostumusta toisia paremmin. Vaikka traanien vertikaaliset rasvahappoprofiilit antavat mitä ilmeisimmin yksilökohtaista tietoa eläinten ravinnosta ja aineenvaihdunnasta, niitä ei ole pystytty tulkitsemaan aiemmissa tutkimuksissa kovinkaan syvällisesti. Nämä tulokset voivatkin osaltaan auttaa tulkitsemaan traanin vertikaalisia rasvahappoprofiileja tulevaisuudessa. Saatuja tuloksia voidaan lisäksi hyödyntää myös hylkeiden ravintokohteiden arvioinnissa käytettävien näytteenottoprotokollien suunnitteluun ja kehittämiseen.

Kainate receptors (KARs) are glutamate receptors that modulate neurotransmission and neuronal excitability. They assemble from five subunits (GRIK1-5 or GluK1-5) present at both pre- and postsynaptic membranes. KAR function is regulated by neuropilin and tolloid-like (NETO) proteins, which also regulate postsynaptic GRIK2 abundance. Some KAR subunit gene variants associate with psychiatric disorders. Moreover, Grik1, Grik2 and Grik4 knock-out (KO) mice display changes in anxiety- and fear-related behaviours. In previous work, Neto2 KO mice expressed higher fear and impaired fear extinction in the fear conditioning paradigm. We hypothesised that this phenotype could be due to reduced KAR subunit abundance in fear-related brain regions, i.e. ventral hippocampus, amygdala and medial prefrontal cortex (mPFC). We specifically investigated GRIK2/3 and GRIK5 levels in the subcellular synaptosomal (SYN) fraction using western blot. We did not observe any difference between genotypes in any of the brain regions. However, our statistical power may have been insufficient, particularly for amygdala and mPFC. Also, an effect on synaptic KAR subunit abundance might be specific to either pre- or postsynaptic compartment, and thus more difficult to detect in SYN fractions. Alternatively, NETO2 absence may affect KAR actions instead of their subunit levels in fear-related brain regions, which could be examined through electrophysiological recordings. Ultimately, unravelling how a molecular system without NETO2 gives rise to fear behaviour in mice may lead to a better understanding of fear-related disorders in human and to new therapeutic strategies.

Citizen science is a research method in which data collection, analysis or other stages of research is distributed to a large number of volunteers. Citizen science enables collection of large-scale data. In addition, in few cases Citizen science has been integrated into formal school education. It has been found to attract students' interest in the subject and research and to teach students about scientific research. However, the real benefits of citizen science for schools have been just scarcely studied. This study explored the experiences of middle school and high school students on the Helsinki Urban Rat Project (Kaupunkirottatutkimus). The research questions were: (1) How do the middle school and high school students who participated in the Urban Rat Project experience citizen science as part of biology teaching? (2.) How do the students who participated in the Urban Rat Project feel about urban rats and how does the Project affect students’ perception of rats? The data was collected by group theme interviews from middle school and high school students who participated in the City Rat Project. The data consisted of nine recorded interviews with a total of 29 interviewees. The interviews were transcribed and analyzed by content analysis. The Urban Rat Project aroused situational interest towards urban rats and research project. Main factors for aroused interest were novelty and specialty of the project, the involvement created by hands-on activities and the meaningfulness created by contextualism of an authentic research. Learning experiences were categorized by Bloom’s revised taxonomy and the results revealed a number of knowledge types and cognitive process categories, suggesting that the project developed a diverse range of students' thinking. Students were able to develop deeper research skills, critically explore research and its outcomes, and learn about practical challenges and constraints of scientific research. Urban rats gave rise to both negative, positive and neutral feelings among students. The negative emotions were caused by a variety of causes, such as the appearance and behavior of rats, culture created attitudes and students own experiences. Positive feelings were caused by interest toward rats and good experiences with pets. The knowledge learned in the study about urban rats generally reduced negative feelings and in one case aroused them, but many interviewees also felt that the study had no effect on their attitude towards rats, because interaction with rats was not concrete enough during the project and the students were disappointed that they did not see rats or rat footprints. The authentic research context of citizen science such as Urban Rat Project can increase meaningfulness to studying biology, which is not necessarily achieved by other teaching methods and may teach the realities of scientific research better than traditional practical work. In addition, citizen science can provide knowledge and nature experiences that allow learners to reflect on their relationship with nature. In order to achieve nature-related learning goals of the school education, citizen science projects should pay particular attention to the concreteness of the interaction between learners and nature and to the students' experiences in nature during citizen science.