SUN domain proteins are integral proteins of the inner nuclear membrane and functions in linkage of the nuclear lamina to the cytoskeleton. Moreover, SUN domain proteins seem to mediate the tethering ...of the centrosome to the nuclear membrane, and they are involved in telomere attachment to the nuclear envelope in meiotic cells, and in germ cell development in invertebrates. In contrast to the widely expressed SUN domain proteins in mammals, SUN1 and SUN2, which have been analysed in great detail, there is virtually nothing known about testicular SUN domain proteins. Since a hallmark of male germ cell development is the profound remodelling of the nuclear envelope, emphasized, for example, by the reshaping of the nucleus during spermiogenesis, and the biogenesis of its tightly associated acrosome, SUN domain proteins might be engaged in these processes. We have isolated a novel SUN domain protein, SPAG4L-2, that differs from SPAG4L by an N-terminal insertion of 25 amino acids. Spag4l and Spag4l-2 are exclusively expressed in testis at about equimolar amounts, and show elevated transcription during ongoing spermiogenesis coincident with the appearance of round spermatids. Molecular dissection of the protein followed by cytological and biochemical investigations revealed that SPAG4L-2 and SPAG4L are transmembrane proteins that localize to the nuclear envelope. SPAG4L/4L-2 are restricted to the apical nuclear region of round spermatids that face the acrosomic vesicle, and thus are most probably involved in linkage of the acrosomic vesicle to the spermatid nucleus, and in acrosome biogenesis.
Background: Sensory factors are important determinants of appetite and food choices but little is known about the relationship between body weight and sensory capabilities. Objective: To investigate ...the relationship between measured body weights, misreporting of body weight and sensory capabilities. Design: In a cross-sectional sensory study, body weight was assessed by measured and self-reported body weight in healthy men (n=130) and women (n=181). Sensory capabilities were assessed as odour detection and identification, and detection for salty, sweet, sour and bitter taste. Results: Odour detection, odour identification and taste perception scores were lower in subjects with a BMI 28 kg/m2 than in subjects with a BMI <28 kg/m2 in the age group <65 years whereas in subjects >or= 65 years scores were higher in subjects with a BMI >or= 28 kg/m2 than in subjects with a BMI <28 kg/m2 (BMIage group: P=0.015, 0.053 and 0.015, respectively). Independent of age, scores were highest in under reporters of body weight (P=0.008, 0.001 and 0.017). Differences in taste perception could be attributed to sour (P=0.015) and bitter (P=0.026) perception, but not to salty or sweet perception. Conclusion: Relationship between sensory capabilities and body mass is age dependent. Compared to overweight subjects, the sensory capabilities of normal weight individuals appear to be higher (<65 years) and lower (>or= 65 years). At any age, however, subjects who under reported their body weight show higher sensory capabilities.
The glutamatergic system is the most widespread neurotransmitter system in the mammalian brain. It is connected to the acetylcholinergic neurotransmitter system to form the ...glutamatergic/aspartatergic-acetylcholinergic circuit, which is the morphobiochemical basis of learning, memory and cognition assisted by the glutamatergic N-methyl-D-aspartate receptor, which mediates long-term potentiation as the fundamental molecular mechanisms of these mental capacities. Glutamate and acetylcholine as ligands of the two neurotransmitter systems are products of the neuronal glucose metabolism as holds true also for advanced glycation end products (AGEs), which are markers of damaged and/or aged proteins. During normal aging, both the neurotransmitters glutamate and acetylcholine undergo strong functional variations. Their synthesis was found to be reduced as a common feature. In contrast, basal release of acetylcholine and receptor number decrease, whereas basal release of glutamate and receptor number increase. AGEs increase during aging obviously preferentially in glutamatergic pyramidal neurons in cerebral cortical layers prone to neurodegeneration. In sporadic Alzheimer disease (SAD), glutamate concentration was shown to fall since it may serve as a substitute for lacking glucose in the beginning of the disease. In contrast, glutamate receptor density was found to be much less involved indicating an excessive activation of the glutamatergic neurotransmitter system particularly via the NMDA receptor, mediating endogenous excitotoxicity. The morphological hallmarks of SAD neuritic plaques and neurofibrillary tangles have been demonstrated to crosslink with AGEs causing an increased rate of free radical production. First data from animal studies and investigations on human beings may indicate that the NMDA receptor antagonist memantine may have beneficial effects on the course of SAD and its clinical symptoms.
•The Competitive Attention Test, is suitable for characterizing distractibility in children as young as four.•Task-irrelevant distractors induced distraction, phasic arousal, and impulsivity in four- ...and five-year-olds.•Sustained attention, as assessed by the Competitive Attention Test, improved with age.•Children from lower socioeconomic backgrounds showed reduced sustained attention and greater impulsivity.
In children, the ability to attend to relevant auditory information and ignore distracting information is crucial for learning and educational achievement. Distractibility, the propensity to pay attention to irrelevant information, depends on multiple components of cognition (voluntary attention orienting, sustained attention, distraction resulting from the capture of attention by a distractor, phasic arousal, impulsivity, and motor control) that may mature at different ages. Here, we used the Competitive Attention Test (CAT) to measure these components in children aged 3 to 5 years. Our goal was to characterize changes in the efficiency of attention during the preschool period and to determine whether distractibility varies as a function of socioeconomic status (SES). All 3-year-olds (n = 14) and some 4- and 5-year-olds (n = 21) needed to be excluded from the sample due to noncompliance with instructions, suggesting that the CAT might not be suitable for children with poorly developed skills in sustained attention. Among 4- and 5-year-olds who completed the CAT (n = 71), sustained attention improved with age, whereas voluntary attention orienting remained immature. Independent of age, task-irrelevant sounds induced distraction, phasic arousal, and impulsivity. There was no relationship between SES and children’s distraction. Finally, children from lower SES backgrounds showed reduced sustained attention abilities and increased impulsivity. Taken together, these findings suggest that distractibility is still developing during the preschool period and is likely to vary depending on the SES background of a child’s family.
We report the discovery of a brown dwarf on an eccentric orbit and with a semimajor axis that places it in the brown dwarf desert region around the star HD 191760. The star has a spectral type of ...G3IV/V and a metallicity (Fe/H) of 0.29 dex. HD 191760 adds to the small number of metal-rich stars with brown dwarf companions. The brown dwarf (HD 191760b) is found to have an orbital period of 505.57 ± 0.40 d and semimajor axis of 1.35 ± 0.01 au, placing it firmly in the brown dwarf desert. The eccentricity of HD 191760b is found to be 0.63 ± 0.01, meaning it reaches as close as 0.5 au from the host star. Dynamical simulations indicate that no inner planets could reside at separations beyond ∼0.17 au due to the disastrous gravity imposed by HD 191760b. In addition to these first results, we also refine the orbits found for the exoplanets around the stars HD 48265, HD 143361 and HD 154672. All one-planet solutions are in agreement with those previously published by the Magellan Planet Search.
Kepler Object of Interest Network von Essen, C.; Ofir, A.; Dreizler, S. ...
Astronomy and astrophysics (Berlin),
07/2018, Letnik:
615
Journal Article
Recenzirano
Odprti dostop
During its four years of photometric observations, the Kepler space telescope detected thousands of exoplanets and exoplanet candidates. One of Kepler’s greatest heritages has been the confirmation ...and characterization of hundreds of multi-planet systems via transit timing variations (TTVs). However, there are many interesting candidate systems displaying TTVs on such long timescales that the existing Kepler observations are of insufficient length to confirm and characterize them by means of this technique. To continue with Kepler’s unique work, we have organized the “Kepler Object of Interest Network” (KOINet), a multi-site network formed of several telescopes located throughout America, Europe, and Asia. The goals of KOINet are to complete the TTV curves of systems where Kepler did not cover the interaction timescales well, to dynamically prove that some candidates are true planets (or not), to dynamically measure the masses and bulk densities of some planets, to find evidence for non-transiting planets in some of the systems, to extend Kepler’s baseline adding new data with the main purpose of improving current models of TTVs, and to build a platform that can observe almost anywhere on the northern hemisphere, at almost any time. KOINet has been operational since March 2014. Here we show some promising first results obtained from analyzing seven primary transits of KOI-0410.01, KOI-0525.01, KOI-0760.01, and KOI-0902.01, in addition to the Kepler data acquired during the first and second observing seasons of KOINet. While carefully choosing the targets we set demanding constraints on timing precision (at least 1 min) and photometric precision (as good as one part per thousand) that were achieved by means of our observing strategies and data analysis techniques. For KOI-0410.01, new transit data revealed a turnover of its TTVs. We carried out an in-depth study of the system, which is identified in the NASA Data Validation Report as a false positive. Among others, we investigated a gravitationally bound hierarchical triple star system and a planet–star system. While the simultaneous transit fitting of ground- andspace-based data allowed for a planet solution, we could not fully reject the three-star scenario. New data, already scheduled in the upcoming 2018 observing season, will set tighter constraints on the nature of the system.
Disturbances of glucose and energy metabolism are hypothesized as pathogenetic factors in sporadic dementia of Alzheimer type (SDAT). Insulin and is receptors play an important role in the regulation ...of brain glucose metabolism and neuronal growth. In postmortem brain cortex in SDAT, the densities of brain insulin receptors were decreased compared to adult controls, but were increased in relation to aged controls. Tyrosine kinase activity, a signal transduction mechanism common to insulin and IGF-1 receptors, was reduced in SDAT in comparison to middle-aged and age-matched control groups. The data are consistent with a neurotrophic role of insulin in the human brain and an upregulation of insulin receptors is SDAT brain as a compensatory mechanism, possibly due to impaired signal transduction mechanism.
More than a century ago, a densely stained area inside the nucleus of male meiotic cells was described. It was later shown to harbor the sex chromosomes which undergo transcriptional inactivation in ...conjunction with heterochromatinisation and synapsis to form the XY body. Formation of the XY body is conserved throughout the mammalian phylogenetic tree and is thought to be essential for successful spermatogenesis. However, its biological role as well as the molecular mechanisms underlying XY body formation are still far from being understood. A lot of effort has already been undertaken to characterize components of the XY body and to investigate their functional implications in sex chromatin heterochromatinisation and meiotic sex chromosome inactivation (MSCI). This review gives an overview of those components and their possible implications in XY body formation and function.
The search for the causes of neurodegenerative disorders is a major theme in brain research. Acquired disturbances of several aspects of cellular metabolism appear pathologically important in ...sporadic Alzheimer's disease (SDAT). Among these brain glucose utilisation is reduced in the early stages of the disease and the regulatory enzymes important for glucose metabolism are reduced. In the brain, insulin, insulin-like growth factors and their receptors regulate glucose metabolism and promote neuronal growth. To detect changes in the functional activity of the brain insulin neuromodulatory system of SDAT patients, we determined the concentrations of insulin and c-peptide as well as insulin receptor binding and IGF-I receptor binding in several regions of postmortem brain cortex during aging and Alzheimer's disease. Additionally, we performed immunohistochemical staining with antibodies against insulin in neocortical brain areas in SDAT and controls. We show for the first time that insulin and c-peptide concentration in the brain are correlated and decrease with aging, as do brain insulin receptor densities. Weak insulin-immunoreactivity could be demonstrated histochemically in pyramidal neurons of controls, whereas in SDAT a stronger insulin-immunoreactivity was found. On a biochemical level, insulin and c-peptide levels were reduced compared to middle-aged controls, but were unchanged compared to age-matched controls. Brain insulin receptor densities in SDAT were decreased compared to middle-aged controls, but increased in comparison to age-matched controls. IGF-I receptor densities were unchanged in aging and in SDAT. Tyrosine kinase activity, a signal transduction mechanism common to both receptor systems, was reduced in SDAT in comparison to middle-aged and age-matched control groups. These data are consistent with a neurotrophic role of insulin in the human brain and a disturbance of insulin signal transduction in SDAT brain and favor the hypothesis that insulin dependent functions may be of pathogenetic relevance in sporadic SDAT.
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