Browsing by Subject "plasticity"

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  • van Bemmelen, Rob S. A.; Kolbeinsson, Yann; Ramos, Raül; Gilg, Olivier; Alves, José A.; Smith, Malcolm; Schekkerman, Hans; Lehikoinen, Aleksi; Petersen, Ib Krag; Þórisson, Böðvar; Sokolov, Aleksandr A.; Välimäki, Kaisa; van der Meer, Tim; Okill, J. David; Bolton, Mark; Moe, Børge; Hanssen, Sveinn Are; Bollache, Loïc; Petersen, Aevar; Thorstensen, Sverrir; González-Solís, Jacob; Klaassen, Raymond H. G.; Tulp, Ingrid (2019)
    Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but only few studies compare movement strategies between populations using distinct migration routes and wintering areas. In thisour study, individual movement strategies of Rred-necked pPhalaropes Phalaropus lobatus, a long-distance migratory wader using saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed the existence of two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km – largely over land – to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, birds wintering in the Pacific were stationaryresided in roughly a singlethe same area, whereas individuals wintering in the Arabian Sea showed individually consistent movementsd extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.
  • Pihlajoki, Marjut; Doerner, Julia; Cochran, Rebecca S.; Heikinheimo, Markku; Wilson, David B. (2015)
    The adrenal cortex is divided into concentric zones. In humans the major cortical zones are the zona glomerulosa, zona fasciculata, and zona reticularis. The adrenal cortex is a dynamic organ in which senescent cells are replaced by newly differentiated ones. This constant renewal facilitates organ remodeling in response to physiological demand for steroids. Cortical zones can reversibly expand, contract, or alter their biochemical profiles to accommodate needs. Pools of stem/progenitor cells in the adrenal capsule, subcapsular region, and juxtamedullary region can differentiate to repopulate or expand zones. Some of these pools appear to be activated only during specific developmental windows or in response to extreme physiological demand. Senescent cells can also be replenished through direct lineage conversion; for example, cells in the zona glomerulosa can transform into cells of the zona fasciculata. Adrenocortical cell differentiation, renewal, and function are regulated by a variety of endocrine/paracrine factors including adrenocorticotropin, angiotensin II, insulin-related growth hormones, luteinizing hormone, activin, and inhibin. Additionally, zonation and regeneration of the adrenal cortex are controlled by developmental signaling pathways, such as the sonic hedgehog, delta-like homolog 1, fibroblast growth factor, and WNT/1-catenin pathways. The mechanisms involved in adrenocortical remodeling are complex and redundant so as to fulfill the offsetting goals of organ homeostasis and stress adaptation.
  • Voipio, Mikko Emil Olavi (Helsingin yliopisto, 2020)
    Nitric oxide (NO) is an important signalling molecule in the brain. NO regulates the function of many proteins by e.g. interacting with tyrosine and cysteine residues, thus inducing post-translational modifications. In animal models, inhibition of NO production triggers behavioural effects similarly to those induced by antidepressant drugs. Receptor tropomyosin-related kinase B (TRKB) has been identified as a key player mediating antidepressant drug (AD) induced effects, and it’s a potential target for NO since it displays multiple potential sites for nitration. Preliminary results from our group indicate that TRKB nitration impairs its signalling, and AD uncouple many proteins from TRKB and reorganizes TRKB protein complex. We examined the effect of selective nitric oxide synthase (NOS) inhibitor N⍵-propyl-L-arginine (NPA) in mice submitted to the contextual fear conditioning and found out that inhibiting NO production with NPA has an antidepressant-like effect on mice. We also found out that AD fluoxetine prevents nitration of TRKB receptors in vivo and antidepressant drugs fluoxetine, phenelzine and imipramine disrupt the interactions of TRKB, NOS1 and NOS1 adaptor protein (CAPON) in co-immunoprecipitation assay. To understand the nature of TRKB and NOS1 interaction, we thus examined the protein domains in NOS1 and TRKB using Uniprot database, and we were unable to identify sites that could interact directly. Literature search for NOS1 adapting proteins followed by Uniprot data mining indicated CAPON as a potential candidate to mediate NOS1: TRKB interaction. Our data shows for the first time that antidepressant drugs disrupt TRKB:CAPON:NOS1 interaction, thus protecting TRKB from NOS1-induced nitration. ADs might induce their behavioural effects by preventing NO-induced impair in TRKB signalling
  • Halonen, Risto; Kuula, Liisa; Lahti, Jari; Makkonen, Tommi; Räikkönen, Katri; Pesonen, Anu-Katriina (2019)
    A common single nucleotide polymorphism (SNP) of the brain-derived neurotrophic factor (BDNF) gene, Val66Met, has been reported to impair BDNF secretion and memory function. However, few studies have investigated the interaction of BDNF genotype and sleep characteristics, such as sleep spindles, that promote long-term potentiation during sleep. In this study we compared overnight visual memory between the carriers of BDNF Met and non-carriers (Val homozygotes), and examined how sleep spindle density associated with memory performance. The sample constituted of 151 adolescents (mean age 16.9 years; 69% Val homozygotes, 31% Met carriers). The learning task contained high and low arousal pictures from Interactive Affective Picture System. The learning task and all-night polysomnography were conducted at the homes of the adolescents. Slow (10–13 Hz) and fast (13–16 Hz) spindles were detected with automated algorithm. Neither post-sleep recognition accuracy nor spindle density differed between Val homozygotes and Met carriers. While frontal slow and fast spindle densities associated with better recognition accuracy in the entire sample, examining the allelic groups separately indicated paralleling associations in Val homozygotes only. Interaction analyses revealed a significant genotype-moderated difference in the associations between frontal fast sleep spindles and high arousal pictures. In sum, sleep spindles promote or indicate visual learning in Val homozygote adolescents but not in Met carriers. The result suggests that the role of sleep spindles in visual recognition memory is not equal across individuals but moderated by a common gene variant.
  • Moliner, Rafael (Helsingin yliopisto, 2019)
    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.
  • McFarlane, S. Eryn; Ålund, Murielle; Sirkiä, Päivi M.; Qvarnström, Anna (2018)
    Variation in relative fitness of competing recently formed species across heterogeneous environments promotes coexistence. However, the physiological traits mediating such variation in relative fitness have rarely been identified. Resting metabolic rate (RMR) is tightly associated with life history strategies, thermoregulation, diet use, and inhabited latitude and could therefore moderate differences in fitness responses to fluctuations in local environments, particularly when species have adapted to different climates in allopatry. We work in a long-term study of collared (Ficedula albicollis) and pied flycatchers (Ficedula hypoleuca) in a recent hybrid zone located on the Swedish island of Oland in the Baltic Sea. Here, we explore whether differences in RMR match changes in relative performance of growing flycatcher nestlings across environmental conditions using an experimental approach. The fitness of pied flycatchers has previously been shown to be less sensitive to the mismatch between the peak in food abundance and nestling growth among late breeders. Here, we find that pied flycatcher nestlings have lower RMR in response to higher ambient temperatures (associated with low food availability). We also find that experimentally relaxed nestling competition is associated with an increased RMR in this species. In contrast, collared flycatcher nestlings did not vary their RMR in response to these environmental factors. Our results suggest that a more flexible nestling RMR in pied flycatchers is responsible for the better adaptation of pied flycatchers to the typical seasonal changes in food availability experienced in this hybrid zone. Generally, subtle physiological differences that have evolved when species were in allopatry may play an important role to patterns of competition, coexistence, or displacements between closely related species in secondary contact.
  • Maria del Mar Delgadoa,1,2, Tomas Roslinb,2, Gleb Tikhonovc, Evgeniy Meyked, Coong Loc, Eliezer Gurariee, Marina Abadonovaf, Ozodbek Abduraimovg, Olga Adrianovah, Tatiana Akimovai, Muzhigit Akkievj, Aleksandr Ananink,l, Elena Andreevam, Natalia Andriychukn, Maxim Antipino, Konstantin Arzamascevp, Svetlana Babinaq, Miroslav Babushkinr, Oleg Bakins, Anna Barabancovat, Inna Basilskajau, Nina Belovav, Natalia Belyaevaw, Tatjana Bespalovax, Evgeniya Bisikalovay, Anatoly Bobretsovz, Vladimir Bobrovaa, Vadim Bobrovskyibb, Elena Bochkarevacc,dd, Gennady Bogdanovee, Vladimir Bolshakovff, Svetlana Bondarchukgg, Evgeniya Bukharovak,3, Alena Butuninax, Yuri Buyvolovhh, Anna Buyvolovaii, Yuri Bykovjj, Elena Chakhirevas, Olga Chashchinakk, Nadezhda Cherenkovall, Sergej Chistjakovmm, Svetlana Chuhontsevai, Evgeniy A. Davydovcc,nn, Viktor Demchenkooo, Elena Diadichevaoo, Aleksandr Dobrolyubovpp, Ludmila Dostoyevskayaqq, Svetlana Drovninall, Zoya Drozdovajj, Akynaly Dubanaevrr, Yuriy Dubrovsky...; Kurhinen, Juri (2020)
    For species to stay temporally tuned to their environment, they use cues such as the accumulation of degree-days. The relationships between the timing of a phenological event in a population and its environmental cue can be described by a population-level reaction norm. Variation in reaction norms along environmental gradients may either intensify the envi- ronmental effects on timing (cogradient variation) or attenu- ate the effects (countergradient variation). To resolve spatial and seasonal variation in species’ response, we use a unique dataset of 91 taxa and 178 phenological events observed across a network of 472 monitoring sites, spread across the nations of the former Soviet Union. We show that compared to local rates of advancement of phenological events with the advancement of temperature-related cues (i.e., variation within site over years), spatial variation in reaction norms
  • Danesi, Claudia Elisabetta; Keinänen, Kari Pekka; Castren, Maija Liisa (2019)
    Fragile X syndrome (FXS) is a neurodevelopmental disorder that represents a common cause of intellectual disability and is a variant of autism spectrum disorder (ASD). Studies that have searched for similarities in syndromic and non-syndromic forms of ASD have paid special attention to alterations of maturation and function of glutamatergic synapses. Copy number variations (CNVs) in the loci containing genes encoding alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs) subunits are associated with ASD in genetic studies. In FXS, dysregulated AMPAR subunit expression and trafficking affect neural progenitor differentiation and synapse formation and neuronal plasticity in the mature brain. Decreased expression of GluA2, the AMPAR subunit that critically controls Ca2+-permeability, and a concomitant increase in Ca2+-permeable AMPARs (CP-AMPARs) in human and mouse FXS neural progenitors parallels changes in expression of GluA2-targeting microRNAs (miRNAs). Thus, posttranscriptional regulation of GluA2 by miRNAs and subsequent alterations in calcium signaling may contribute to abnormal synaptic function in FXS and, by implication, in some forms of ASD.
  • Varón-González, Ceferino; Fraimout, Antoine; Delapré, Arnaud; Debat, Vincent; Cornette, Raphaël (2020)
    Phenotypic plasticity has been repeatedly suggested to facilitate adaptation to new environmental conditions, as in invasions. Here, we investigate this possibility by focusing on the worldwide invasion of Drosophila suzukii: an invasive species that has rapidly colonized all continents over the last decade. This species is characterized by a highly developed ovipositor, allowing females to lay eggs through the skin of ripe fruits. Using a novel approach based on the combined use of scanning electron microscopy and photogrammetry, we quantified the ovipositor size and three-dimensional shape, contrasting invasive and native populations raised at three different developmental temperatures. We found a small but significant effect of temperature and geographical origin on the ovipositor shape, showing the occurrence of both geographical differentiation and plasticity to temperature. The shape reaction norms are in turn strikingly similar among populations, suggesting very little difference in shape plasticity among invasive and native populations, and therefore rejecting the hypothesis of a particular role for the plasticity of the ovipositor in the invasion success. Overall, the ovipositor shape seems to be a fairly robust trait, indicative of stabilizing selection. The large performance spectrum rather than the flexibility of the ovipositor would thus contribute to the success of D. suzukii worldwide invasion.
  • Tolmacheva, Aleksandra; Savolainen, Sarianna; Kirveskari, Erika; Lioumis, Pantelis; Kuusela, Linda; Brandstack, Nina; Ylinen, Aarne; Mäkelä, Jyrki P.; Shulga, Anastasia (2017)
    A large proportion of spinal cord injuries (SCI) are incomplete. Even in clinically complete injuries, silent non-functional connections can be present. Therapeutic approaches that can strengthen transmission in weak neural connections to improve motor performance are needed. Our aim was to determine whether long-term delivery of paired associative stimulation (PAS, a combination of transcranial magnetic stimulation [TMS] with peripheral nerve stimulation [PNS]) can enhance motor output in the hands of patients with chronic traumatic tetraplegia, and to compare this technique with long-term PNS. Five patients (4 males; age 38-68, mean 48) with no contraindications to TMS received 4 weeks (16 sessions) of stimulation. PAS was given to one hand and PNS combined with sham TMS to the other hand. Patients were blinded to the treatment. Hands were selected randomly. The patients were evaluated by a physiotherapist blinded to the treatment. The follow-up period was 1 month. Patients were evaluated with Daniels and Worthingham's Muscle Testing (0-5 scale) before the first stimulation session, after the last stimulation session, and 1 month after the last stimulation session. One month after the last stimulation session, the improvement in the PAS-treated hand was 1.02 +/- 0.17 points (p <0.0001, n = 100 muscles from 5 patients). The improvement was significantly higher in PAS-treated than in PNS-treated hands (176 +/- 29%, p = 0.046, n = 5 patients). Longterm PAS might be an effective tool for improving motor performance in incomplete chronic SCI patients. Further studies on PAS in larger patient cohorts, with longer stimulation duration and at earlier stages after the injury, are warranted.
  • Viskari, Ansa (Helsingfors universitet, 2012)
    The purpose of this study was to investigate how the mixing time of the magnesium stearate affects on the compressibility of partially pregelatinized maize starch. Pregelatinized maize starch is used in pharmaceuticals as a filler, binder and as disintegrant. Because pregelatinized maize starch has lubricant characteristics itself, it is known to be sensitive for the amount and the mixing time of magnesium stearate. The aim is that magnesium stearate is not totally homogenously mixed on the powder surfaces so that even, clean powder surfaces exist. Homogeneous mixing means that particles are coated with magnesium stearate, which as a hydrophobic ingredient prevents bond formation between plastically and elastically behaving particles. Too much magnesium stearate and/or too long mixing time may cause weakening of tablet tensile strength, laminating and capping. The weakening of the tensile strength of the tablet increases friability, which causes problems during packaging process and the transportation. Too much magnesium stearate may also lengthen the disintegration time and slow down the dissolution. The aim of this study was to compare four different brands of pregelatinized maize starch. The purpose was to find differences affecting the compressibility behavior. Also the effect of the mixing time of magnesium stearate for compression behavior of masses were studied. The brands investigated were C*PharmGel DC 93000, Lycatab® C, Starch 1500® and SuperStarch 200®. First mentioned was a reference product which is not manufactured any more. There was only one batch of the reference product but three batches from other products to be able to investigate also batch to batch variation. The characteristics studied from pregelatinized starch samples were bulk density, apparent density and true density, flowability, moisture sorption, moisture content, pH value, swelling volume and particle size. Also NIR, FTIR and Raman spectroscopy and X-ray powder diffraction method were used. Weight, tensile strength, dimensions, friability, disintegration time and moisture sorption were studied for tablets. The compressibility of the mass and elastic behavior of tablets was studied. Pictures of the tablets were also taken by scanning electron microscope. When the mixing time of magnesium stearate was increased from 2 minutes to 5 minutes, the compression pressure needed for pressing tablets for 80 N strength increased 200-700 N depending on the brand of pregelatinized maize starch. Based on the results the best alternative to replace C*PharmGel DC 93000 was chosen to be SuperStarch 200®. Scanning electron microscope pictures showed that C*PharmGel DC 93000 deviates from other qualities studied by being roundish and regular in shape. SuperStarch 200® and Starch 1500® reminded remarkably each other. Lycatab® C was the biggest in particle size and very irregular in shape. The differences found in tabletting followed the expectations based on the SEM-pictures. SuperStarch 200® showed to best compressibility in lowest strain strength and after C*PharmGel DC 93000 it was least sensitive for mixing time of the magnesium stearate. It also has least elastic recovery. The differences between SuperStarch 200® and Starch 1500® in compression properties were moderate but clear. Lycatab® C had clearly the weakest compression properties.
  • Garcia, Raquel A.; Araujo, Miguel B.; Burgess, Neil D.; Foden, Wendy B.; Gutsche, Alexander; Rahbek, Carsten; Cabeza, Mar (2014)
  • Castren, Eero; Hen, Rene (2013)
  • Lesnikova, Angelina; Casarotto, Plinio; Moliner, Rafael; Fred, Senem Merve; Biojone, Caroline; Castren, Eero (2021)
    Perineuronal nets (PNNs) have an important physiological role in the retention of learning by restricting cognitive flexibility. Their deposition peaks after developmental periods of intensive learning, usually in late childhood, and they help in long-term preservation of newly acquired skills and information. Modulation of PNN function by various techniques enhances plasticity and regulates the retention of memories, which may be beneficial when memory persistence entails negative symptoms such as post-traumatic stress disorder (PTSD). In this study, we investigated the role of PTP sigma [receptor-type tyrosine-protein phosphatase S, a phosphatase that is activated by binding of chondroitin sulfate proteoglycans (CSPGs) from PNNs] in retention of memories using Novel Object Recognition and Fear Conditioning models. We observed that mice haploinsufficient for PTPRS gene (PTP sigma(+/-)), although having improved short-term object recognition memory, display impaired long-term memory in both Novel Object Recognition and Fear Conditioning paradigm, as compared to WT littermates. However, PTP sigma(+/-) mice did not show any differences in behavioral tests that do not heavily rely on cognitive flexibility, such as Elevated Plus Maze, Open Field, Marble Burying, and Forced Swimming Test. Since PTP sigma has been shown to interact with and dephosphorylate TRKB, we investigated activation of this receptor and its downstream pathways in limbic areas known to be associated with memory. We found that phosphorylation of TRKB and PLC gamma are increased in the hippocampus, prefrontal cortex, and amygdaloid complex of PTP sigma(+/-) mice, but other TRKB-mediated signaling pathways are not affected. Our data suggest that PTP sigma downregulation promotes TRKB phosphorylation in different brain areas, improves short-term memory performance but disrupts long-term memory retention in the tested animal models. Inhibition of PTP sigma or disruption of PNN-PTP sigma-TRKB complex might be a potential target for disorders where negative modulation of the acquired memories can be beneficial.
  • Pesonen, Anu-Katriina; Merikanto, Ilona; Halonen, Risto; Ujma, Peter; Makkonen, Tommi; Räikkönen, Katri; Lahti, Jari; Kuula, Liisa (2020)
    Sleep spindles are thalamocortical oscillations that contribute to sleep maintenanceand sleep-related brain plasticity. The current study is an explorative study of the cir-cadian dynamics of sleep spindles in relation to a polygenic score (PGS) for circadianpreference towards morningness. The participants represent the 17-year follow-upof a birth cohort having both genome-wide data and an ambulatory sleep electroen-cephalography measurement available (N= 154, Mean age = 16.9, SD = 0.1 years,57% girls). Based on a recent genome-wide association study, we calculated a PGSfor circadian preference towards morningness across the whole genome, including354 single-nucleotide polymorphisms. Stage 2 slow (9-12.5 Hz,N= 186 739) andfast (12.5-16 Hz,N= 135 504) sleep spindles were detected using an automatedalgorithm with individual time tags and amplitudes for each spindle. There was a sig-nificant interaction of PGS for morningness and timing of sleep spindles across thenight. These growth curve models showed a curvilinear trajectory of spindle ampli-tudes: those with a higher PGS for morningness showed higher slow spindle ampli-tudes in frontal derivations, and a faster dissipation of spindle amplitude in centralderivations. Overall, the findings provide new evidence on how individual sleep spin-dle trajectories are influenced by genetic factors associated with circadian type. Thefinding may lead to new hypotheses on the associations previously observedbetween circadian types, psychiatric problems and spindle activity.
  • Woestmann, Luisa; Saastamoinen, Marjo (2016)
    The importance of trans-generational effects in shaping an individuals' phenotype and fitness, and consequently even impacting population dynamics is increasingly apparent. Most of the research on trans-generational effects still focuses on plants, mammals, and birds. In the past few years, however, increasing number of studies, especially on maternal effects, have highlighted their importance also in many insect systems. Lepidoptera, specifically butterflies, have been used as model systems for studying the role of phenotypic plasticity within generations. As ectotherms, they are highly sensitive to environmental variation, and indeed many butterflies show adaptive phenotypic plasticity in response to environmental conditions. Here, we synthesize what is known about trans-generational effects in Lepidoptera, compile evidence for different environmental cues that are important drivers of trans-generational effects, and point out which offspring traits are mainly impacted. Finally, we emphasize directions for future research that are needed for better understanding of the adaptive nature of trans-generational effects in Lepidoptera in particular, but potentially also in other organisms.