Browsing by Subject "Sexual dimorphism"

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  • Herczeg, Gabor; Gonda, Maria Abigel; Balazs, Gergely; Noreikiene, Kristina; Merila, Juha (2015)
    Background: Plasticity in brain size and the size of different brain regions during early ontogeny is known from many vertebrate taxa, but less is known about plasticity in the brains of adults. In contrast to mammals and birds, most parts of a fish's brain continue to undergo neurogenesis throughout adulthood, making lifelong plasticity in brain size possible. We tested whether maturing adult three-spined sticklebacks (Gasterosteus aculeatus) reared in a stimulus-poor environment exhibited brain plasticity in response to environmental enrichment, and whether these responses were sex-specific, thus altering the degree of sexual size dimorphism in the brain. Results: Relative sizes of total brain and bulbus olfactorius showed sex-specific responses to treatment: males developed larger brains but smaller bulbi olfactorii than females in the enriched treatment. Hence, the degree of sexual size dimorphism (SSD) in relative brain size and the relative size of the bulbus olfactorius was found to be environment-dependent. Furthermore, the enriched treatment induced development of smaller tecta optica in both sexes. Conclusions: These results demonstrate that adult fish can alter the size of their brain (or brain regions) in response to environmental stimuli, and these responses can be sex-specific. Hence, the degree of SSD in brain size can be environment-dependent, and our results hint at the possibility of a large plastic component to SSD in stickleback brains. Apart from contributing to our understanding of the processes shaping and explaining variation in brain size and the size of different brain regions in the wild, the results show that provision of structural complexity in captive environments can influence brain development. Assuming that the observed plasticity influences fish behaviour, these findings may also have relevance for fish stocking, both for economical and conservational purposes.
  • Schalekamp-Timmermans, Sarah; Arends, Lidia R.; Alsaker, Elin; Chappell, Lucy; Hansson, Stefan; Harsem, Nina K.; Jalmby, Maya; Jeyabalan, Arundhathi; Laivuori, Hannele; Lawlor, Debbie A.; Macdonald-Wallis, Corrie; Magnus, Per; Myers, Jenny; Olsen, Jorn; Poston, Lucilla; Redman, Christopher W.; Staff, Anne C.; Villa, Pia; Roberts, James M.; Steegers, Eric A.; Global Pregnancy Collaboration (2017)
    Background: Pre-eclampsia (PE) is a major pregnancy disorder complicating up to 8% of pregnancies. Increasing evidence indicates a sex-specific interplay between the mother,placenta and fetus. This may lead to different adaptive mechanisms during pregnancy. Methods: We performed an individual participant data meta-analysis to determine associations of fetal sex and PE, with specific focus on gestational age at delivery in PE. This was done on 219 575 independent live-born singleton pregnancies, with a gestational age at birth between 22.0 and 43.0 weeks of gestation, from 11 studies participating in a worldwide consortium of international research groups focusing on pregnancy. Results: Of the women, 9033 (4.1%) experienced PE in their pregnancy and 48.8% of the fetuses were female versus 51.2% male. No differences in the female/male distribution were observed with respect to term PE (delivered >= 37 weeks). Preterm PE (delivered <37 weeks) was slightly more prevalent among pregnancies with a female fetus than in pregnancies with a male fetus [odds ratio (OR) 1.11, 95% confidence interval (CI) 1.02-1.21]. Very preterm PE (delivered <34 weeks) was even more prevalent among pregnancies with a female fetus as compared with pregnancies with a male fetus (OR 1.36, 95% CI 1.17-1.59). Conclusions: Sexual dimorphic differences in the occurrence of PE exist, with preterm PE being more prevalent among pregnancies with a female fetus as compared with pregnancies with a male fetus and with no differences with respect to term PE.
  • Schalekamp-Timmermans, Sarah; Arends, Lidia R.; Alsaker, Elin; Chappell, Lucy; Hansson, Stefan; Harsem, Nina K.; Jalmby, Maya; Jeyabalan, Arundhathi; Laivuori, Hannele; Lawlor, Debbie A.; Macdonald-Wallis, Corrie; Magnus, Per; Myers, Jenny; Olsen, Jorn; Poston, Lucilla; Redman, Christopher W.; Staff, Anne C.; Villa, Pia; Roberts, James M.; Steegers, Eric A.; Global Pregnancy Collaboration (Oxford University Press, 2017)
    Background: Pre-eclampsia (PE) is a major pregnancy disorder complicating up to 8% of pregnancies. Increasing evidence indicates a sex-specific interplay between the mother,placenta and fetus. This may lead to different adaptive mechanisms during pregnancy. Methods: We performed an individual participant data meta-analysis to determine associations of fetal sex and PE, with specific focus on gestational age at delivery in PE. This was done on 219 575 independent live-born singleton pregnancies, with a gestational age at birth between 22.0 and 43.0 weeks of gestation, from 11 studies participating in a worldwide consortium of international research groups focusing on pregnancy. Results: Of the women, 9033 (4.1%) experienced PE in their pregnancy and 48.8% of the fetuses were female versus 51.2% male. No differences in the female/male distribution were observed with respect to term PE (delivered >= 37 weeks). Preterm PE (delivered <37 weeks) was slightly more prevalent among pregnancies with a female fetus than in pregnancies with a male fetus [odds ratio (OR) 1.11, 95% confidence interval (CI) 1.02-1.21]. Very preterm PE (delivered <34 weeks) was even more prevalent among pregnancies with a female fetus as compared with pregnancies with a male fetus (OR 1.36, 95% CI 1.17-1.59). Conclusions: Sexual dimorphic differences in the occurrence of PE exist, with preterm PE being more prevalent among pregnancies with a female fetus as compared with pregnancies with a male fetus and with no differences with respect to term PE.
  • Kuula, Liisa; Tamminen, Jakke; Makkonen, Tommi; Merikanto, Ilona; Räikkönen, Katri; Pesonen, Anu-Katriina (2019)
    Background: Sleep facilitates the extraction of semantic regularities amongst newly encoded memories, which may also lead to increased false memories. We investigated sleep stage proportions and sleep spindles in the recollection of adolescents' false memories, and their potential sex-specific differences. Methods: 196 adolescents (mean age 16.9 y; SD = 0.1, 61% girls) underwent the Deese, Roediger & McDermott (DRM) false memory procedure and overnight polysomnography, with free recall the following morning. Sleep was scored manually into stages 1, 2, 3 and REM. Stage 2 sleep spindle frequency, density, and peak amplitude were used as measures of spindle activity for slow (10-13 Hz) and fast (13-16 Hz) ranges. Results: In girls, a lower number of critical lures was associated with higher spindle frequency (p Conclusions: In adolescent girls, higher spindle activity was associated with fewer critical lures being falsely recalled in the DRM paradigm. Unlike studies using adult participants, we did not observe any association between slow-wave sleep and false memory recollection.
  • Xia, Zhichao; He, Yue; Zhou, Bin; Korpelainen, Helena; Li, Chunyang (2020)
    Extensive research has shown that dioecious plants exhibit sexual dimorphism under extreme environments. However, sex-specific differences in responses to drought, phosphorus (P) shortage or their combination are less known. In our study, impacts of drought, P shortage and their combination on the performance of Populus cathayana males and females were investigated. Drought and P deficiency caused a greater negative impact on female growth than on male growth. P application ameliorated the more negative effect of drought on the shoot dry matter accumulation and P concentration in male leaves, while smaller effects were observed in females. The concentration of citrate in the rhizosphere of males was higher under drought combined with P application than under adequate water availability, and the increase was greater in males than in females. Males also showed a higher abundance of main soil microbial groups, including bacteria, actinomycetes, arbuscular mycorrhizal fungi (AMF), and Gram+ and Gram- bacteria in the rhizosphere, resulting in a more resistant microhabitat. In contrast, the abundance of bacteria and AMF was less in the rhizosphere of females exposed to stress conditions, while saprophytic fungi increased significantly. P enhanced drought resistance more in stress-resistant males but less in females under relatively severe drought stress. Increased drought resistance by P in males might be associated with greater plasticity in rhizosphere processes when compared with females.
  • Liu, Miao; Liu, Xiucheng; Zhao, Yang; Korpelainen, Helena; Li, Chunyang (2022)
    Nitrogen (N) partitioning within a leaf affects leaf photosynthesis and adaptation to environmental fluctuations. However, how plant sex influences leaf N allocation and its tradeoffs in acclimation to drought, excess salt and their combination remains unknown. Here, leaf N allocation between the photosynthetic and non-photosynthetic apparatus and among the components of the photosynthesis in Populus cathayana Rehder females and males were investigated under drought, salt and their combination to clarify the underlying mechanism. We found that males with a lower leaf N allocation (NL) into non-protein N (Nnp), showed a greater leaf N allocation into photosynthetic apparatus, especially into the carboxylation component under all treatments, and a greater leaf N allocation into cell wall under drought and salt stress alone, consequently causing higher photosynthetic N use efficiency (PNUE) and tolerance to stresses. Conversely, females had a greater leaf N allocation into Nnp under all treatments than males and a lower leaf photosynthetic N (NP) allocation. There was a tradeoff in leaf N allocation among photosynthetic apparatus (NP/NL), cell wall (NCW/NL) and Nnp, which explained plant responses to drought, salt and their combination. Moreover, the leaf N allocation into the carboxylation component could explain the intersexual difference in responses to all treatments, while leaf cell wall N (NCW) and Nnp reflected intrasexual differences among treatments in both sexes. These findings indicate sex-specific strategies in coping with drought, salt and their combination that relate to leaf N allocation, which may contribute to sex-specific photosynthesis and niche segregation.
  • Ahlström, Fredrik; Mätlik, Kert; Blomqvist, Kim; Liu, Xiaonan; Lilius, Tuomas; Sidorova, Yulia; Kalso, Eija; Rauhala, Pekka; Viisanen, Hanna (Helsingin yliopisto, 2020)
    Neuropatisk smärta (NS) är vanligare hos kvinnor. Fastän nyligen utförd forskning tyder på att patofysiologin är olik hos könen, har primärt handjur studerats tidigare. För att bättre förstå könsskillnader vid NS undersökte vi hon- och hanråttors smärtbeteende efter en perifer nerv-skada samt analyserade vävnader med systembiologiska metoder. En perifer nervskada orsakades hos hon- och hanråttor, sham-operationer utfördes på kontroll-grupperna. Mekanisk och köldallodyni mättes med von Frey filament, respektive acetontest före operationerna, efter sju och 21 dagar. Ryggmärgsprovers och dorsalrotsganglioners genexpress-ion analyserades sju dagar efter operationerna. L4-L5 ryggmärgssegment (IBA1 och GFAP) och dorsalrotsganglionerna (CGRP och IB-4) samlades för immunohistokemi och cerebrospinal-vätska för proteomik efter 21 dagar. En kraftigare mekanisk allodyni uppstod hos honråttorna. Bägge könen utvecklade en tidig kraf-tig köldallodyni. De immunohistokemiska markörerna påvisade en liknande nervskada i dorsal-rotganglierna och liknande mikroglia- och astrocytaktivitet i ryggmärgen hos könen. Cerebrospi-nalvätskans proteiner påverkades inte. Många gener i dorsalrotsganglierna visade könsspecifik genexpression efter nervskadan, exempelvis cd28, cd274, ctla4, dpp4, hrh3, il1b och thbs4; i ryggmärgen uppvisade bland annat generna atf3, ccl2, och pdyn könsspecifika förändringar. Hondjuren uppvisade kraftigare smärtbeteende, och vi identifierade många gener som kunde förklara den observerade skillnaden. T-lymfocytresponsen och flera andra till NS kopplade mekanismer verkar vara olika i de två könen. Generna är kandidater för vidare forskning och våra resultat understryker betydelsen av att könen undersöks skilt i smärtstudier. (219 ord)
  • Buechel, Severine D.; Noreikiene, Kristina; DeFaveri, Jacquelin; Toli, Elisavet; Kolm, Niclas; Merila, Juha (2019)
    Snapshot analyses have demonstrated dramatic intraspecific variation in the degree of brain sexual size dimorphism (SSD). Although brain SSDis believed to be generated by the sex-specific cognitive demands of reproduction, the relative roles of developmental and population-specific contributions to variation in brain SSD remain little studied. Using a common garden experiment, we tested for sex-specific changes in brain anatomy over the breeding cycle in three-spined stickleback (Gasterosteus aculeatus) sampled from four locations in northern Europe. We found that the male brain increased in size (ca. 24%) significantly more than the female brain towards breeding, and that the resulting brain SSD was similar (ca. 20%) for all populations over the breeding cycle. Our findings support the notion that the stickleback brain is highly plastic and changes over the breeding cycle, especially in males, likely as an adaptive response to the cognitive demands of reproduction (e.g. nest construction and parental care). The results also provide evidence to suggest that breeding-related changes in brain size may be the reason for the widely varying estimates of brain SSD across studies of this species, cautioning against interpreting brain size measurements from a single time point as fixed/static.