Selective modification of cytoplasmic membrane fluidity by catalytic hydrogenation provides evidence on its primary role in chilling susceptibility of the blue-green alga, Anacystis nidulans

AbstractCytoplasmic and thylakoid membranes were isolated at different stages of catalytic hydrogenation of fatty acyl double bonds in living cells of Anacystis nidulans. The reaction was limited to the lipids of cell-surface membranes during the initial period of hydrogenation, thus, we were able to produce alga cells, modified exclusively in the cytoplasmic membrane. In these unique cells, neither compositional nor physical changes were detected in the lipid phase of thylakoids. Due to the rigidification of the alkyl chains of its lipids, however, the cytoplasmic membrane became leaky and phase separated at considerably higher chilling temperatures.Since an irreversible inactivation of photosynthetic electron transport was found simultaneously, it provided direct evidence for the hypothesis that the thermotropic properties of the lipids within cytoplasmic membranes, and not those of the thylakoids, control chilling susceptibility of the blue-green alga, A.nidulans

Increased overall cortical connectivity with syndrome specific local decreases suggested by atypical sleep-EEG synchronization in Williams syndrome

Williams syndrome (7q11.23 microdeletion) is characterized by specific alterations in neurocognitive architecture and functioning, as well as disordered sleep. Here we analyze the region, sleep state and frequency-specific EEG synchronization of whole night sleep recordings of 21 Williams syndrome and 21 typically developing age- and gender-matched subjects by calculating weighted phase lag indexes. We found broadband increases in inter- and intrahemispheric neural connectivity for both NREM and REM sleep EEG of Williams syndrome subjects. These effects consisted of increased theta, high sigma, and beta/low gamma synchronization, whereas alpha synchronization was characterized by a peculiar Williams syndrome-specific decrease during NREM states (intra- and interhemispheric centro-temporal) and REM phases of sleep (occipital intra-area synchronization). We also found a decrease in short range, occipital connectivity of NREM sleep EEG theta activity. The striking increased overall synchronization of sleep EEG in Williams syndrome subjects is consistent with the recently reported increase in synaptic and dendritic density in stem-cell based Williams syndrome models, whereas decreased alpha and occipital connectivity might reflect and underpin the altered microarchitecture of primary visual cortex and disordered visuospatial functioning of Williams syndrome subjects

Long-range alpha and beta and short-range gamma EEG synchronization distinguishes phasic and tonic REM periods

info:eu-repo/semantics/publishe

Hyperarousal captured in increased number of arousal events during pre-REM periods in individuals with frequent nightmares

The aim of this study was to investigate hyperarousal in individuals with frequent nightmares (NM participants) by calculating arousal events during nocturnal sleep. We hypothesized an increased number of arousals in NM participants compared with controls, especially during those periods where the probability of spontaneous arousal occurrence is already high, such as non-rapid eye movement to rapid eye movement transitions (pre-rapid eye movement periods). Twenty-two NM participants and 23 control participants spent two consecutive nights in our sleep laboratory, monitored by polysomnography. Arousal number and arousal length were calculated only for the second night, for 10 min before rapid eye movement (pre-rapid eye movement) and 10 min after rapid eye movement (post-rapid eye movement) periods, as well as non-rapid eye movement and rapid eye movement phases separately. Repeated-measures ANOVA model testing revealed significant Group (NM participants, controls) x Phase (pre-rapid eye movement, post-rapid eye movement) interaction in case of the number of arousals. Furthermore, post hoc analysis showed a significantly increased number of arousals during pre-rapid eye movement periods in NM participants, compared with controls, a difference that disappeared in post-rapid eye movement periods. We propose that focusing the analyses of arousals specifically on state transitory periods offers a unique perspective into the fragile balance between the sleep-promoting and arousal systems. This outlook revealed an increased number of arousals in NM participants, reflecting hyperarousal during pre-rapid eye movement periods

Visual imagery vividness declines across the lifespan

The capacity to elicit vivid visual mental images varies within an extensive range across individuals between hyper- and aphantasia. It is not clear, however, whether imagery vividness is constant across the lifespan or changes during development and later in life. Without enforcing the constraints of strict experimental procedures and representativity across the entire population, our purpose was to explore the self-reported level of imagery vividness and determine the relative proportions of aphantasic/hyperphantasic participants in different age groups. Relying on the frequently used Vividness of Visual Imagery Questionnaire, we collected data on a random sample of 2252 participants between the ages of 12–60 years. We found a novel developmental pattern that describes a declining ability to elicit vivid visual mental images in the group averages of different age groups from adolescence to middle age. This effect involves both a decreasing proportion of individuals with vivid visual imagery vividness and an increasing proportion of individuals with low imagery vividness as maturation (based on bone age assessments in adolescents) and ageing progress. These findings may shed some light on the developmental mechanisms of our internal, stimulus-independent processes, and might also help to determine genetic, maturational, and age-dependent factors in the cases of hyper- and aphantasia

Repeated afternoon sleep recordings indicate first‐night‐effect‐like adaptation process in family dogs

info:eu-repo/semantics/publishe

A több évtizeden át tartó testedzés hatása az irizin hormon szintjére

Kutatásunk során célul tűztük ki, hogy felderítsük az élethosszon át tartó edzés hatását a vér irizin szintjére. Vizsgálatunkban edzett és nem edzett közép/időskorú személyek vettek részt. Az irizin hormon, ami egy myokin és adipokin, a fizikai aktivitás során termelődik a peroxiszóma proliferátor aktivált receptor gamma koaktivátor 1 alfa (PGC1A) fehérje jelenlétében. Az irizin számos fontos élettani hatással bír, melyek főként fizikai aktivitás hatására aktiválódnak. Elsősorban a szervezet anyagcsere folyamatait szabályozza, de kapcsolatba hozták már az agyműködéssel és a telomer hosszal is. Legjobb tudomásunk szerint korábban nem vizsgálták még a több évtizedes edzés hatását az irizinre. Eredményeink alapján azt találtuk, hogy az irizin hormon szintje nem mutat korrelációt a VO2max értékkel. Többváltozós regressziós analízis alkalmazása során az irizin és a HDL koncentrációja a vérben korrelációt mutatott egymással a különböző funkcionális paraméterek figyelembe vétele mellett. Maximális erő mérés eredményei alapján az edzett és az edzetlen férfi csoport nagyobb maximális erővel rendelkezik, mint az edzett és edzetlen női csoport, azonban a két férfi csoport között nem mutatható ki különbség. Az edzett férfiak robbanékony ereje nagyobb a két női csoporthoz képest. A becsült VO2max értékek szignifikánsan magasabbak az edzett férfi csoportban az edzetlen csoportokhoz képest. Az edzett nők magasabb HDL szinttel rendelkeznek, mint az edzetlen férfiak és az edzetlen nők. A HDL, mint előnyös funkciókkal rendelkező lipoprotein, elképzelhető, hogy hasonló élettani adaptációs folyamatok mentén fejti ki a hatásait, mint az irizin. A VO2max és az irizin szint között nem találtunk korrelációt, amiből arra következtethetünk, hogy az edzésre adott élettani válaszok komplexebbek annál, minthogy egyetlen mutatóval próbáljuk meg jellemezni azt