Browsing by Subject "ORIENTATION"

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  • Linek, Nils; Brzek, Pawel; Gienapp, Phillip; O'Mara, M. Teague; Pokrovsky, Ivan; Schmidt, Andreas; Shipley, J. Ryan; Taylor, Jan R. E.; Tiainen, Juha; Volkmer, Tamara; Wikelski, Martin; Partecke, Jesko (2021)
    Background Many birds species range over vast geographic regions and migrate seasonally between their breeding and overwintering sites. Deciding when to depart for migration is one of the most consequential life-history decisions an individual may make. However, it is still not fully understood which environmental cues are used to time the onset of migration and to what extent their relative importance differs across a range of migratory strategies. We focus on departure decisions of a songbird, the Eurasian blackbird Turdus merula, in which selected Russian and Polish populations are full migrants which travel relatively long-distances, whereas Finnish and German populations exhibit partial migration with shorter migration distances. Methods We used telemetry data from the four populations (610 individuals) to determine which environmental cues individuals from each population use to initiate their autumn migration. Results When departing, individuals in all populations selected nights with high atmospheric pressure and minimal cloud cover. Fully migratory populations departed earlier in autumn, at longer day length, at higher ambient temperatures, and during nights with higher relative atmospheric pressure and more supportive winds than partial migrants; however, they did not depart in higher synchrony. Thus, while all studied populations used the same environmental cues, they used population-specific and locally tuned thresholds to determine the day of departure. Conclusions Our data support the idea that migratory timing is controlled by general, species-wide mechanisms, but fine-tuned thresholds in response to local conditions.
  • Kaltiala-Heino, Riittakerttu; Lindberg, Nina; Fröjd, Sari; Haravuori, Henna; Marttunen, Mauri (2019)
    Purpose: To explore whether sexual harassment experiences are more common among adolescents reporting romantic and erotic interests in the same sex and both sexes, when sociodemographic and mental health confounding are controlled for, and whether the associations are similar in both sexes and in different phases of adolescence. Methods: A cross-sectional survey among a nationally representative dataset of 25,147 boys and 25,257 girls in comprehensive school, and 33,231 boys and 36,765 girls in upper secondary education. Self-reports of experiences of sexual harassment, and emotional (depression) and behavioral (delinquency) symptoms were used. Results: All associations between sexual minority status and harassment diminished clearly when mental disorder dimensions were controlled for. In the comprehensive school sample (mean age 15.4 years), sexual harassment experiences were 4-7-fold more common among boys, and 1.5-3-fold among girls, with same-sex/both-sexes interest, compared to those interested exclusively in the opposite sex. In the upper secondary education sample (mean age 17.4 years), among boys, sexual harassment was reported 3-6-fold more commonly by those not exclusively heterosexually interested. Among older girls, a slight increase in sexual harassment experiences was seen among those interested in both sexes. Conclusions: Sexual harassment experiences are associated with sexual minority status, particularly among boys. Confounding by mental disorders needs to be accounted for when studying sexual minority status and sexual harassment.
  • Nissinen, Terhi S; Maksniemi, Erika; Rothmann, Sebastiaan; Lonka, Kirsti (2022)
    The aim of this study was to investigate how job crafting, work engagement, and workaholism were related in public sector organizations. The participants (N = 213) were civil servants from three Finnish public organizations, representing different professions, such as school personnel, secretaries, directors, parking attendants, and ICT specialists. We duly operationalized job crafting, work engagement, and workaholism by using the Job Crafting Scale, the UWES-9, and the Work Addiction Risk Test. The current study focused on the Finnish public sector, since work engagement is recognized at the governmental level and has been shown to be strongly and positively associated with economic activity and productivity, while workaholism is associated with poor wellbeing. We analyzed the data by using structural equation modeling and found that three job crafting dimensions were strongly intertwined with one another. These dimensions were increasing structural job resources, increasing social job resources, and increasing challenging job demands. In the structural model, dimension "increasing structural job resources" was positively related to work engagement, whereas dimension "decreasing hindering job demands" was negatively associated with workaholism. This study highlighted the relevance of employees learning to balance their job resources and demands. We recommend that, in the public sector, employees be systematically encouraged to practice job crafting behavior by enabling them to increase structural job resources. These results are of high relevance, considering the heavy workload of public sector employees during the COVID-19 pandemic.
  • Kulig, Waldemar; Mikkolainen, Heikki; Olzynska, Agnieszka; Jurkiewicz, Piotr; Cwiklik, Lukasz; Hof, Martin; Vattulainen, Ilpo; Jungwirth, Pavel; Rog, Tomasz (2018)
    Translocation of sterols between cellular membrane leaflets is of key importance in membrane organization, dynamics, and signaling. We present a novel translocation mechanism that differs in a unique manner from the established ones. The bobbing mechanism identified here is demonstrated for tail-oxidized sterols, but is expected to be viable for any molecule containing two polar centers at the opposite sides of the molecule. The mechanism renders translocation across a lipid membrane possible without a change in molecular orientation. For tail-oxidized sterols, the bobbing mechanism provides an exceptionally facile means to translocate these signaling molecules across membrane structures and may thus represent an important pathway in the course of their biological action.
  • Sumia, Maria; Lindberg, Nina; Tyolajarvi, Marja; Kaltiala-Heino, Riittakerttu (2017)
    We studied current (GIDYQ-A) and recalled (RCGI) childhood gender identity among 719 upper secondary school students 401 girls, mean age 17.0 (SD = 0.88) years old and 318 boys, mean age 17.2 (SD = 0.86 years old in Finland. We also compared these dimensions of identity in community youth to same dimensions among adolescent sex reassignment (SR) applicants. Most community youth scored high on the normative, cis-gender end of gender experience (median score 4.9 for boys and 4.9 for girls) and recalled fairly gender typical childhood behaviours and experiences. The girls displayed more gender non-conformity in childhood. Among the boys 2.2% and among the girls 0.5% displayed potentially clinically significant gender dysphoria on the GIDYQ-A. The community youth differed clearly from adolescent SR applicants on current and recalled childhood gender identity (SR applicants were 47, 6 natal boys and 41 natal girls, average ages were 16.4 years old (SD = 0.93) and girls were on average 16.8 years old (SD = 1.0). (C) 2017 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.
  • Miettinen, Simo S. A.; Makinen, Tatu J.; Laaksonen, Inari; Mäkelä, Keijo; Huhtala, Heini; Kettunen, Jukka; Remes, Ville (2017)
    Purpose Early aseptic loosening of cementless monoblock acetabular components is a rare complication of total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA). The purpose of this study was to evaluate the incidence and risk factors for early aseptic loosening of the cementless monoblock acetabular components. Methods This retrospective analysis consisted of 4,043 cementless hip devices (3,209 THAs and 834 HRAs). We identified 41 patients with early aseptic loosening of the acetabular component. A control group of 123 patients without acetabular component loosening was randomly selected. The demographic data and risk factors for loosening of the acetabular component were evaluated. The mean follow-up time was 4.6 years (range, 1.7-7.8). The end-point was acetabular revision. Results The incidence of early acetabular component loosening was 1.0 %. Mean time to revision was 1.2 years (SD 1.6, range 0.0-5.4). There was significantly more Dorr type A and C acetabular morphology in patients with early loosening (P = 0.014). The loosened components were implanted to more vertical (P <0.001) and less anteverted (P = 0.001) position than those of the control group. Presence of acetabular dysplasia or acetabular component type did not associate to early loosening. Conclusions Acetabular morphology (Dorr type A and C) and component positioning vertically and less anteverted were more common in patients with early aseptic loosening of cementless acetabular components. Suboptimal cup position most likely reflects challenges to obtain sufficient stability during surgery. We hypothesize that errors in surgical technique are the main reason for early loosening of monoblock acetabular components.
  • Laiti, Minna; Pakarinen, Anni; Parisod, Heidi; Salanterä, Sanna; Sariola, Salla (2019)
    Aim: To describe the encounters with sexual and gender minority (SGM) youth in healthcare based on the existing research. Background: The development of sexual orientation and gender identity can create challenges in an SGM youth's life, and they may need support from health professionals. Heteronormativity has been recognised as a barrier to the identification of diversity in sexuality and gender, and no previous literature review has studied heteronormativity thoroughly. Methods: An integrative review following Whittemore and Knafl was conducted. A literature search was systematically undertaken in six databases (PubMed/MEDLINE, CINAHL, Cochrane Library, PsycINFO, Eric, and Academic Search Premier). Finally, 18 research articles were included. Data were analysed deductively with the theoretical framework from Stevi Jackson's (2006) article to understand the role of heteronormativity in the healthcare of SGM youth. Findings: The encounters with SGM youth consisted of two simultaneous themes. Heteronormative care included three elements: (1) the effect of heteronormativity on health professionals' competence to work with SGM youth, (2) false assumptions about SGM youth, and (3) the influence of heteronormativity on encounters with SGM youth. Diversity-affirming care included two elements: (4) the considerateness of health professionals towards SGM youth and (5) inclusive care of SGM youth. Conclusion: This review summarised how SGM youth were encountered in healthcare and how heteronormativity was affecting their healthcare. Furthermore, this review identified elements that supported diversity-affirming care. With diversity-affirming care, SGM youth may access the information and support they need from healthcare. Further research is needed about how diversity-affirming care can be applied to the healthcare of SGM youth and how elements of heteronormative care are occurring globally in the healthcare of SGM youth. The perceptions of transgender and other gender minority youth were under-represented in the studies and research needs to focus more on how they are encountered in healthcare.
  • Suvanto, Hannele; Niemi, Jarkko K.; Lahdesmaki, Merja (2020)
    Protein crops are important in enhancing sustainable and self-contained agriculture and food security in Europe. Individual farmers are key players in protein crop production. The aim of this research is to understand how an entrepreneurial identity affects strategic cultivation decisions in the context of protein-rich crop farming. In this study, entrepreneurial identity consists of a farmer's personal and entrepreneurial orientations. Data on 308 Finnish farmers were gathered and statistically tested. Our findings clarify that entrepreneurial identity increases the probability of beginning protein-rich crop cultivation, especially if the farmer in question is innovative, a risk-taker and highly educated. This article contributes to the understanding of agricultural entrepreneurship and strategic cultivation decisions made by different kinds of farmers. We further claim that profitable but risky and demanding crops have tempted farmers with a high entrepreneurial identity for the most part, which would not suffice for protein crops to become mainstream.
  • Galemou Yoga, Etienne; Parey, Kristian; Djurabekova, Amina; Haapanen, Outi; Siegmund, Karin; Zwicker, Klaus; Sharma, Vivek; Zickermann, Volker; Angerer, Heike (2020)
    Respiratory complex I catalyzes electron transfer from NADH to ubiquinone (Q) coupled to vectorial proton translocation across the inner mitochondrial membrane. Despite recent progress in structure determination of this very large membrane protein complex, the coupling mechanism is a matter of ongoing debate and the function of accessory subunits surrounding the canonical core subunits is essentially unknown. Concerted rearrangements within a cluster of conserved loops of central subunits NDUFS2 (beta 1-beta 2(S2) loop), ND1 (TMH5-6(ND1) loop) and ND3 (TMH1-2(ND3) loop) were suggested to be critical for its proton pumping mechanism. Here, we show that stabilization of the TMH1-2(ND3) loop by accessory subunit LYRM6 (NDUFA6) is pivotal for energy conversion by mitochondrial complex I. We determined the high-resolution structure of inactive mutant F89A(LYRM6) of eukaryotic complex I from the yeast Yarrowia lipolytica and found long-range structural changes affecting the entire loop cluster. In atomistic molecular dynamics simulations of the mutant, we observed conformational transitions in the loop cluster that disrupted a putative pathway for delivery of substrate protons required in Q redox chemistry. Our results elucidate in detail the essential role of accessory subunit LYRM6 for the function of eukaryotic complex I and offer clues on its redox-linked proton pumping mechanism. Respiratory complex I plays a key role in energy metabolism. Cryo-EM structure of a mutant accessory subunit LYRM6 from the yeast Yarrowia lipolytica and molecular dynamics simulations reveal conformational changes at the interface between LYRM6 and subunit ND3, propagated further into the complex. These findings offer insight into the mechanism of proton pumping by respiratory complex I.
  • Åkesson, Susanne; Atkinson, Phil W.; Bermejo, Ana; de la Puente, Javier; Ferri, Mauro; Hewson, Chris M.; Holmgren, Jan; Kaiser, Erich; Kearsley, Lyndon; Klaassen, Raymond H. G.; Kolunen, Heikki; Matsson, Gittan; Minelli, Fausto; Norevik, Gabriel; Pietiäinen, Hannu; Singh, Navinder J.; Spina, Fernando; Viktora, Lukas; Hedenström, Anders (2020)
    Spectacular long-distance migration has evolved repeatedly in animals enabling exploration of resources separated in time and space. In birds, these patterns are largely driven by seasonality, cost of migration, and asymmetries in competition leading most often to leapfrog migration, where northern breeding populations winter furthest to the south. Here, we show that the highly aerial common swiftApus apus, spending the nonbreeding period on the wing, instead exhibits a rarely found chain migration pattern, where the most southern breeding populations in Europe migrate to wintering areas furthest to the south in Africa, whereas the northern populations winter to the north. The swifts concentrated in three major areas in sub-Saharan Africa during the nonbreeding period, with substantial overlap of nearby breeding populations. We found that the southern breeding swifts were larger, raised more young, and arrived to the wintering areas with higher seasonal variation in greenness (Normalized Difference Vegetation Index) earlier than the northern breeding swifts. This unusual chain migration pattern in common swifts is largely driven by differential annual timing and we suggest it evolves by prior occupancy and dominance by size in the breeding quarters and by prior occupancy combined with diffuse competition in the winter.
  • Aivelo, Tuomas; Uitto, Anna (2021)
    Understanding how teaching affects students' attitudes and beliefs is notoriously difficult, specifically in a quickly evolving and societally relevant field such as genetics. The aim of this survey study is to capitalize our previous research and examine how teaching relates to Finnish secondary school students' liking of, self-concept in and experienced utility of genetics, attitude towards gene technology and belief in genetic determinism. In this unique setting, we used as explanatory variables their teachers' teaching emphases and learning materials, and as student-related factors, we used gender and the number of biology courses attended. Item-response theory with exploratory, confirmatory, and explanatory analyses were carried out to model the data. Teaching explained students' attitudes and beliefs: if the teacher's emphasis was Hereditary or the textbook with stronger Mendelian emphasis was used, students tended to havemore negative attitudes towards learning genetics and stronger belief in genetic determinism . Our results also suggest gender differences: male students had more positive attitude towards gene technology, higher self-concept, whereas as utility of genetics and belief in genetic determinism were higher in females. The results suggest that teaching' approaches as well as learning materials need updates to fulfil the needs for genetics literacy
  • Nava, Michele M.; Miroshnikova, Yekaterina A.; Biggs, Leah C.; Whitefield, Daniel B.; Metge, Franziska; Boucas, Jorge; Vihinen, Helena; Jokitalo, Eija; Li, Xinping; García Arcos, Juan Manuel; Hoffmann, Bernd; Merkel, Rudolf; Niessen, Carien M.; Dahl, Kris Noel; Wickström, Sara A. (2020)
    Summary Tissue homeostasis requires maintenance of functional integrity under stress. A central source of stress is mechanical force that acts on cells, their nuclei, and chromatin, but how the genome is protected against mechanical stress is unclear. We show that mechanical stretch deforms the nucleus, which cells initially counteract via a calcium-dependent nuclear softening driven by loss of H3K9me3-marked heterochromatin. The resulting changes in chromatin rheology and architecture are required to insulate genetic material from mechanical force. Failure to mount this nuclear mechanoresponse results in DNA damage. Persistent, high-amplitude stretch induces supracellular alignment of tissue to redistribute mechanical energy before it reaches the nucleus. This tissue-scale mechanoadaptation functions through a separate pathway mediated by cell-cell contacts and allows cells/tissues to switch off nuclear mechanotransduction to restore initial chromatin state. Our work identifies an unconventional role of chromatin in altering its own mechanical state to maintain genome integrity in response to deformation.
  • Parey, Kristian; Haapanen, Outi; Sharma, Vivek; Köfeler, Harald; Züllig, Thomas; Prinz, Simone; Siegmund, Karin; Wittig, Ilka; Mills, Deryck J.; Vonck, Janet; Kühlbrandt, Werner; Zickermann, Volker (2019)
    Respiratory complex I is a redox-driven proton pump, accounting for a large part of the electrochemical gradient that powers mitochondrial adenosine triphosphate synthesis. Complex I dysfunction is associated with severe human diseases. Assembly of the one-megadalton complex I in the inner mitochondrial membrane requires assembly factors and chaperones. We have determined the structure of complex I from the aerobic yeast Yarrowia lipolytica by electron cryo-microscopy at 3.2-angstrom resolution. A ubiquinone molecule was identified in the access path to the active site. The electron cryo-microscopy structure indicated an unusual lipid-protein arrangement at the junction of membrane and matrix arms that was confirmed by molecular simulations. The structure of a complex I mutant and an assembly intermediate provide detailed molecular insights into the cause of a hereditary complex I-linked disease and complex I assembly in the inner mitochondrial membrane.
  • Parey, Kristian; Lasham, Jonathan; Mills, Deryck J.; Djurabekova, Amina; Haapanen, Outi; Yoga, Etienne Galemou; Xie, Hao; Kuhlbrandt, Werner; Sharma, Vivek; Vonck, Janet; Zickermann, Volker (2021)
    Mitochondrial NADH:ubiquinone oxidoreductase (complex I) is a 1-MDa membrane protein complex with a central role in energy metabolism. Redox-driven proton translocation by complex I contributes substantially to the proton motive force that drives ATP synthase. Several structures of complex I from bacteria and mitochondria have been determined, but its catalytic mechanism has remained controversial. We here present the cryo-EM structure of complex I from Yarrowia lipolytica at 2.1-angstrom resolution, which reveals the positions of more than 1600 protein-bound water molecules, of which similar to 100 are located in putative proton translocation pathways. Another structure of the same complex under steady-state activity conditions at 3.4-angstrom resolution indicates conformational transitions that we associate with proton injection into the central hydrophilic axis. By combining high-resolution structural data with site-directed mutagenesis and large-scale molecular dynamic simulations, we define details of the proton translocation pathways and offer insights into the redox-coupled proton pumping mechanism of complex I.
  • Miettinen, S. S. A.; Mäkinen, T. J.; Mäkelä, K.; Huhtala, H.; Kettunen, J. S.; Remes, V. (2018)
    Background and Aims: Large-diameter head total hip arthroplasty and hip resurfacing arthroplasty were popular in Finland from 2000 to 2012 for the treatment of hip osteoarthritis. The aim of this retrospective study was to investigate the mid-term survival of large-diameter head total hip arthroplasty patients operated on in three university hospitals and to compare these results to the survival of hip resurfacing arthroplasty patients. Material and Methods: A total of 3860 hip arthroplasties (3029 large-diameter head total hip arthroplasties in 2734 patients and 831 hip resurfacing arthroplasties in 757 patients) were operated on between January 2004 and December 2009. The mean follow-up was 4.3years (range: 0.3-8.0years) in the total hip arthroplasty group and 5.1years (range: 1.7-7.9years) in the hip resurfacing arthroplasty group. Cox multiple regression model and Kaplan-Meier survival analysis were used to study the survival of the total hip arthroplasties and the hip resurfacing arthroplasties. Intraoperative complications and reasons for revisions were also evaluated. Results: In Cox regression analysis, the hazard ratio for revision of hip resurfacing arthroplasty was 1.5 compared with large-diameter head total hip arthroplasty (95% confidence interval: 1.0-2.2) (p=0.029). The cumulative Kaplan-Meier survival rate was 90.7% at 7.7years for the large-diameter head total hip arthroplasty (95% confidence interval: 86.8-94.6) and 92.2% at 7.6years for hip resurfacing arthroplasty (95% confidence interval: 89.9-94.6). There were a total of 166/3029 (5.5%) intraoperative complications in the large-diameter head total hip arthroplasty group and 20/831 (2.4%) in the hip resurfacing arthroplasty group (p=0.001). Revision for any reason was performed on 137/3029 (4.5%) of the arthroplasties in the large-diameter head total hip arthroplasty group and 52/831 (6.3%) in the hip resurfacing arthroplasty group (p=0.04). Conclusion: The mid-term survival of both of these devices was poor, and revisions due to adverse reactions to metal debris will most likely rise at longer follow-up. There were more intraoperative complications in the large-diameter head total hip arthroplasty group than in the hip resurfacing arthroplasty group.
  • Rasool, Shahid; Cerchione, Roberto; Salo, Jari; Ferraris, Alberto; Abbate, Stefano (2021)
    Purpose This study aims to examine the role of hunger, environmental, economic, landfill and water shortage concerns as significant dimensions of consumer social awareness marketing in socially responsible plate food consumption. Design/methodology/approach To carry out their purpose, the authors validate the hypothesized model empirically through data from 1,536 households using structural equation modeling (SEM). In particular, the construct measures of the structural model have been tested by confirmatory factor analysis (CFA). Findings The outcome the authors came up with is coherent with the hypothesized model, and it proves a positive relationship of the five dimensions identified on consumer awareness. Moreover, the study results show the crucial role of landfill and water shortage concerns in measuring consumer awareness. Practical implications These findings may be of interest to practitioners, academics and policymakers for socially responsible food consumption guidance and training for planning consumer awareness programs. More in detail, this study offers the indication that the dimensions of the social consumer awareness construct are differing from commercial consumer awareness. Originality/value Even though several previous studies have addressed the concept of consumer awareness concerning product and service purchase decisions, this is one of the first research studies on consumer awareness as a multidimensional construct in social marketing studies domain.
  • Heino, Elias; Fröjd, Sari; Marttunen, Mauri; Kaltiala, Riittakerttu (2020)
    Background: Sexuality is a major facet of development during adolescence. Apace with normal sexual development, sexual experiences become more common and intimate. Recent research reports mixed results as to whether this is the case among transgender identifying adolescents. Recent research also suggests that trans youth experience negative sexual experiences (such as dating violence and sexual harassment) more often than their cisgender identifying peers. However, most studies have had clinical or selected samples. Objective: The aim of this study is to compare the normative as well as negative sexual experiences of trans youth with their cisgender peers in the general population. Method: Our study included 1386 pupils of the ninth year of comprehensive school in Finland, mean age (SD) 15.59 (0.41) years. We compared sexual experiences, sexual harassment and dating violence among trans youth and their cisgender identifying peers. Distributions of the outcome variables were calculated among the whole sample and by sex. Next, multivariate associations were studied using logistic regression adjusting for age, sex, honesty of responding and depression. Odds Ratios (OR) with 95% confidence intervals (CI) are given. Results: After adjusting for age, sex, honesty of responding and ultimately for depression, normative sexual experiences of trans youth did not differ systematically from those of the mainstream, cisgender identifying youth. After adjusting for sex, age and honesty, transgender youth had increased Odds Ratios for experiences of sexual coercion and dating violence perpetration. In the final models however, no statistically significant differences were detected in the negative sexual experiences between transgender and cisgender youth. Conclusion: Transgender identifying adolescents presented neither with delayed nor with excessively advanced sexual experiences. However, transgender youth seem to be more susceptible to subjection to sexual coercion and, unexpectedly, dating violence perpetration than their cisgender peers. However, these associations may in fact relate more closely to depression, a prevalent phenomenon among trans youth, than transgender identity itself.
  • Matamoro-Vidal, Alexis; Huang, Yunxian; Salazar-Ciudad, Isaac; Shimmi, Osamu; Houle, David (2018)
    Quantitative genetic variation in morphology is pervasive in all species and is the basis for the evolution of differences among species. The measurement of morphological form in adults is now beginning to be combined with comparable measurements of form during development. Here we compare the shape of the developing wing to its adult form in a holometabolous insect, Drosophila melanogaster. We used protein expression patterns to measure shape in the developing precursors of the final adult wing. Three developmental stages were studied: late larval third instar, post-pupariation and in the adult fly. We studied wild-type animals in addition to mutants of two genes (shf and ds) that have known effects on adult wing shape and size. Despite experimental noise related to the difficulty of comparing developing structures, we found consistent differences in wing shape and size at each developmental stage between genotypes. Quantitative comparisons of variation arising at different developmental stages with the variation in the final structure enable us to determine when variation arises, and to generate hypotheses about the causes of that variation. In addition we provide linear rules allowing us to link wing morphology in the larva, with wing morphology in the pupa. Our approach provides a framework to analyze quantitative morphological variation in the developing fly wing. This framework should help to characterize the natural variation of the larval and pupal wing shape, and to measure the contribution of the processes occurring during these developmental stages to the natural variation in adult wing morphology.
  • Salmela, Viljami; Socada, Lumikukka; Söderholm, John; Heikkilä, Roope; Lahti, Jari; Ekelund, Jesper; Isometsä, Erkki (2021)
    Background: Previous studies have suggested that processing of visual contrast information could be altered in major depressive disorder. To clarify the changes at different levels of the visual hierarchy, we behaviourally measured contrast perception in 2 centre-surround conditions, assessing retinal and cortical processing. Methods: As part of a prospective cohort study, our sample consisted of controls (n = 29; 21 female) and patients with unipolar depression, bipolar disorder and borderline personality disorder who had baseline major depressive episodes (n = 111; 74 female). In a brightness induction test that assessed retinal processing, participants compared the perceived luminance of uniform patches (presented on a computer screen) as the luminance of the backgrounds was varied. In a contrast suppression test that assessed cortical processing, participants compared the perceived contrast of gratings, which were presented with collinearly or orthogonally oriented backgrounds. Results: Brightness induction was similar for patients with major depressive episodes and controls (p = 0.60, d = 0.115, Bayes factor = 3.9), but contrast suppression was significantly lower for patients than for controls (p < 0.006, d = 0.663, Bayes factor = 35.2). We observed no statistically significant associations between contrast suppression and age, sex, or medication or diagnostic subgroup. At follow-up (n = 74), we observed some normalization of contrast perception. Limitations: We assessed contrast perception using behavioural tests instead of electrophysiology. Conclusion: The reduced contrast suppression we observed may have been caused by decreased retinal feedforward or cortical feedback signals. Because we observed intact brightness induction, our results suggest normal retinal but altered cortical processing of visual contrast during a major depressive episode. This alteration is likely to be present in multiple types of depression and to partially normalize upon remission.
  • Javanainen, Matti; Ollila, O. H. Samuli; Martinez-Seara, Hector (2020)
    Membrane proteins travel along cellular membranes and reorient themselves to form functional oligomers and proteinlipid complexes. Following the Saffman-Delbruck model, protein-radius sets the rate of this diffusive motion. However, it is unclear how this model, derived for ideal and dilute membranes, performs under crowded conditions of cellular membranes. Here, we study the rotational motion of membrane proteins using molecular dynamics simulations of coarse-grained membranes and 2-dimensional Lennard-Jones fluids with varying levels of crowding. We find that the Saffman-Delbruck model captures the size-dependency of rotational diffusion under dilute conditions where protein-protein interactions are negligible, whereas stronger scaling laws arise under crowding. Together with our recent work on lateral diffusion, our results reshape the description of protein dynamics in native membrane environments: The translational and rotational motions of proteins with small transmembrane domains are rapid, whereas larger proteins or protein complexes display substantially slower dynamics.