Summary
Although the evolutionary drivers of genome size change are known, the general patterns and mechanisms of plant genome size evolution are yet to be established. Here we aim to assess the ...relative importance of proliferation of repetitive DNA, chromosomal variation (including polyploidy), and the type of endoreplication for genome size evolution of the Pleurothallidinae, the most species‐rich orchid lineage. Phylogenetic relationships between 341 Pleurothallidinae representatives were refined using a target enrichment hybrid capture combined with high‐throughput sequencing approach. Genome size and the type of endoreplication were assessed using flow cytometry supplemented with karyological analysis and low‐coverage Illumina sequencing for repeatome analysis on a subset of samples. Data were analyzed using phylogeny‐based models. Genome size diversity (0.2–5.1 Gbp) was mostly independent of profound chromosome count variation (2n = 12–90) but tightly linked with the overall content of repetitive DNA elements. Species with partial endoreplication (PE) had significantly greater genome sizes, and genomic repeat content was tightly correlated with the size of the non‐endoreplicated part of the genome. In PE species, repetitive DNA is preferentially accumulated in the non‐endoreplicated parts of their genomes. Our results demonstrate that proliferation of repetitive DNA elements and PE together shape the patterns of genome size diversity in orchids.
Significance Statement
A unique feature of orchids that remains poorly understood is partial endoreplication (PE), a form of endopolyploidy resulting in multiplication of only a fraction of the genome in the course of cell differentiation. Using repeatome analysis within a novel evolutionary frame, we investigated the linkage between PE and genome size evolution in Pleurothallidinae orchids, and showed that proliferation of repetitive elements in PE species enlarges mainly the non‐endoreplicated part of the genome.
IMPORTANCE: Abnormal reward processing is suggested to underlie the formation of psychotic symptoms, likely driven by elevated ventral striatal (VS) dopamine levels. Functional magnetic resonance ...imaging studies reveal alterations of VS activity during reward processing in patients with chronic psychosis and first episode of psychosis, as well as individuals at high risk for psychosis, but findings are inconclusive, conflicting, and difficult to subject to meta-analysis without introducing bias because several studies reported that findings were not statistically significant but did not report statistics. OBJECTIVE: To assess the differences between patients with schizophrenia spectrum disorders and healthy controls in VS activation during reward processing. DATA SOURCES: Web of Knowledge database (incorporating Web of Science and MEDLINE) until July 2015, including references of eligible articles and reviews. STUDY SELECTION: Functional magnetic resonance imaging studies comparing VS activity during monetary reward processing between patients with schizophrenia spectrum disorders or clinical or genetic high-risk state for psychosis and healthy controls. DATA EXTRACTION AND SYNTHESIS: Statistics and thresholds related to the main outcome measures and potential moderators were independently retrieved by 2 investigators. Effect sizes were analyzed using MetaNSUE, a random-effects method that enables the unbiased inclusion of nonstatistically significant unreported effects. MAIN OUTCOMES AND MEASURES: Effect size of the group differences in VS activity, and correlation between VS activity and negative and positive symptom scores in patients. RESULTS: The meta-analysis included 23 studies (917 patients) for reward anticipation, 9 studies (358 patients) for reward feedback, and 8 studies (314 patients) for reward prediction error. We found significant bilateral VS hypoactivation during reward anticipation (23 studies, n = 917) in patients compared with healthy controls (left/right Cohen d, −0.50/−0.70; P < .001). Left VS abnormality was more severe in patients with high scores of negative symptoms during reward anticipation (r = −0.41; P < .001). Patients also showed hypoactivation during reward feedback (left/right d, −0.57/−0.56; P < .001). Simulations showed that exclusion of studies with nonstatistically significant unreported effects was associated with a strong bias (d bias = 0.22), whereas estimations using MetaNSUE were unbiased even when statistics were seldom reported (d bias < 0.001). CONCLUSIONS AND RELEVANCE: This meta-analysis provides evidence that patients with psychosis demonstrate VS hypoactivation during reward anticipation. The assessment of VS prediction errors seems to be promising, but more studies are needed to draw valid conclusions.
•We investigated brain imaging studies focusing on how gut hormones influence brain function regulating appetite in healthy and obese subjects.•Of the 349 studies published before July 2016 ...identified in the database search, 40 were included (27 on healthy and 13 on obese subjects).•Plasma level of ghrelin positively correlate with activation in the pre-frontal cortex, amygdala and insula and negatively subcortical areas.•In contrast, the plasma levels of glucose, insulin, leptin, PYY, GLP-1 affect the same brain in the opposite direction.
The brain–gut-axis is an interdependent system affecting neural functions and controlling our eating behaviour. In recent decades, neuroimaging techniques have facilitated its investigation. We systematically looked into functional and neurochemical brain imaging studies investigating how key molecules such as ghrelin, glucagon-like peptide-1 (GLP-1), peptide tyrosine–tyrosine (PYY), cholecystokinin (CCK), leptin, glucose and insulin influence the function of brain regions regulating appetite and satiety.
Of the 349 studies published before July 2016 identified in the database search, 40 were included (27 on healthy and 13 on obese subjects).
Our systematic review suggests that the plasma level of ghrelin, the gut hormone promoting appetite, is positively correlated with activation in the pre-frontal cortex (PFC), amygdala and insula and negatively correlated with activation in subcortical areas such as the hypothalamus. In contrast, the plasma levels of glucose, insulin, leptin, PYY, GLP-1 affect the same brain regions conversely. Our study integrates previous investigations of the gut-brain matrix during food-intake and homeostatic regulation and may be of use for future meta-analyses of brain-gut interactions.
Next generation metabarcoding is becoming an indispensable tool in fungal community ecology. Here we tested Illumina metabarcoding, a method that generates shorter reads but achieves deeper ...sequencing than 454 metabarcoding approaches. We found that paired-end Illumina MiSeq data cover the full ITS1 in many fungal lineages and are suitable for environmental fungal community assessment. There was substantial read loss during data cleanup (78.6%), which, however, did not impede the analyses, because of the large number of initial sequences (over 4Mio). We observed a high stochasticity in individual PCR reactions. Comparing three repeated sets of PCRs products showed that 58.5% of the total fungal operational taxonomic units (OTUs) found were not recovered by any single set of PCR reactions. Similarly, comparing three annealing temperatures showed that 63.6% of all fungal OTUs were not recovered using any single annealing temperature. These findings suggest that sampling of soil fungal communities is more exhaustive, if we combine repeated PCR products, and PCR products generated at various annealing temperatures. To analyze the above issues we sampled 16 soil cores along a 270 cm transect in a meadow. In total we recovered 3320 fungal OTUs (based on a 95% similarity threshold). Distance decay analysis indicated that community similarity decreased slightly with geographical distance.
•Illumina metabarcoding with ITS1 is suitable for analyzing soil fungal communities.•Read loss due to methodological issues needs to be accounted for when designing study.•Using repeated PCR reactions increases number of OTUs recovered.•Using different annealing temperatures increases number of OTUs recovered.•Deep sequencing reveals significant distance decay in fungal community similarity.
Visual illusions and hallucinations are hallmarks of serotonergic hallucinogen-induced altered states of consciousness. Although the serotonergic hallucinogen psilocybin activates multiple serotonin ...(5-HT) receptors, recent evidence suggests that activation of 5-HT2A receptors may lead to the formation of visual hallucinations by increasing cortical excitability and altering visual-evoked cortical responses. To address this hypothesis, we assessed the effects of psilocybin (215 μg/kg vs placebo) on both α oscillations that regulate cortical excitability and early visual-evoked P1 and N170 potentials in healthy human subjects. To further disentangle the specific contributions of 5-HT2A receptors, subjects were additionally pretreated with the preferential 5-HT2A receptor antagonist ketanserin (50 mg vs placebo). We found that psilocybin strongly decreased prestimulus parieto-occipital α power values, thus precluding a subsequent stimulus-induced α power decrease. Furthermore, psilocybin strongly decreased N170 potentials associated with the appearance of visual perceptual alterations, including visual hallucinations. All of these effects were blocked by pretreatment with the 5-HT2A antagonist ketanserin, indicating that activation of 5-HT2A receptors by psilocybin profoundly modulates the neurophysiological and phenomenological indices of visual processing. Specifically, activation of 5-HT2A receptors may induce a processing mode in which stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation through the modulation of α oscillations. Furthermore, the observed reduction of N170 visual-evoked potentials may be a key mechanism underlying 5-HT2A receptor-mediated visual hallucinations. This change in N170 potentials may be important not only for psilocybin-induced states but also for understanding acute hallucinatory states seen in psychiatric disorders, such as schizophrenia and Parkinson's disease.
IMPORTANCE: Pretest risk estimation is routinely used in clinical medicine to inform further diagnostic testing in individuals with suspected diseases. To our knowledge, the overall characteristics ...and specific determinants of pretest risk of psychosis onset in individuals undergoing clinical high risk (CHR) assessment are unknown. OBJECTIVES: To investigate the characteristics and determinants of pretest risk of psychosis onset in individuals undergoing CHR assessment and to develop and externally validate a pretest risk stratification model. DESIGN, SETTING, AND PARTICIPANTS: Clinical register-based cohort study. Individuals were drawn from electronic, real-world, real-time clinical records relating to routine mental health care of CHR services in South London and the Maudsley National Health Service Trust in London, United Kingdom. The study included nonpsychotic individuals referred on suspicion of psychosis risk and assessed by the Outreach and Support in South London CHR service from 2002 to 2015. Model development and validation was performed with machine-learning methods based on Least Absolute Shrinkage and Selection Operator for Cox proportional hazards model. MAIN OUTCOMES AND MEASURES: Pretest risk of psychosis onset in individuals undergoing CHR assessment. Predictors included age, sex, age × sex interaction, race/ethnicity, socioeconomic status, marital status, referral source, and referral year. RESULTS: A total of 710 nonpsychotic individuals undergoing CHR assessment were included. The mean age was 23 years. Three hundred ninety-nine individuals were men (56%), their race/ethnicity was heterogenous, and they were referred from a variety of sources. The cumulative 6-year pretest risk of psychosis was 14.55% (95% CI, 11.71% to 17.99%), confirming substantial pretest risk enrichment during the recruitment of individuals undergoing CHR assessment. Race/ethnicity and source of referral were associated with pretest risk enrichment. The predictive model based on these factors was externally validated, showing moderately good discrimination and sufficient calibration. It was used to stratify individuals undergoing CHR assessment into 4 classes of pretest risk (6-year): low, 3.39% (95% CI, 0.96% to 11.56%); moderately low, 11.58% (95% CI, 8.10% to 16.40%); moderately high, 23.69% (95% CI, 16.58% to 33.20%); and high, 53.65% (95% CI, 36.78% to 72.46%). CONCLUSIONS AND RELEVANCE: Significant risk enrichment occurs before individuals are assessed for a suspected CHR state. Race/ethnicity and source of referral are associated with pretest risk enrichment in individuals undergoing CHR assessment. A stratification model can identify individuals at differential pretest risk of psychosis. Identification of these subgroups may inform outreach campaigns and subsequent testing and eventually optimize psychosis prediction.
•The paper at hand shows how structural damping and stiffness parameters in shrunk joints can be determined by a generic joint experiment.•With thin layer elements these parameters from the joint ...experiment are coupled to the structures Finite Element Model.•Equivalent modal damping factors can be determined by performing a complex numerical modal analysis, by which the stability of the rotor can be tested.•The two disc rotor is examined as an application sample.•This rotor consists of a shaft with two shrunk-on discs.•With the above mentioned approach, and by considering structural damping added to material damping, the modal damping of the first torsional eigenfrequency is calculated and then compared to the results of an experimental modal analysis.•The paper shows that the presented approach leads to a reliable approximation of the examined structure’s dissipation properties.•It serves as a prediction tool for the response behavior of a turbo-generator.
The paper at hand shows how structural damping and stiffness parameters in shrunk joints can be determined by a generic joint experiment. With thin layer elements these parameters from the joint experiment are coupled to the structures Finite Element Model. Equivalent modal damping factors can be determined by performing a complex numerical modal analysis, by which the stability of the rotor can be tested. The two disc rotor is examined as an application sample. This rotor consists of a shaft with two shrunk-on discs. With the above mentioned approach, and by considering structural damping added to material damping, the modal damping of the first torsional eigenfrequency is calculated and then compared to the results of an experimental modal analysis. The paper shows that the presented approach leads to a reliable approximation of the examined structure’s dissipation properties. It serves as a prediction tool for the response behavior of a turbo-generator.
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