Metabolite profiling reveals complex relationship between developing xylem metabolism and intra-ring checking in Pinus radiata

Globally, there has been an increasing amount of wood harvested from younger, fast-growing trees derived from plantation forests. As a consequence, producers and industrial consumers of wood products are becoming increasingly concerned with not only growth rates, but specific wood attributes that affect processing efficiencies and final product quality. Intra-ring checking is a problem that down-grades an unacceptably high proportion of radiata pine clearwood. Methods of identifying trees prone to this undesirable behaviour have been relatively destructive and time consuming, and from a breeding perspective, to date, there is no reliable method of predicting which selected progeny will later show a propensity to check. Using 120, 7-year-old Pinus radiata clones sampled from a common site, displaying difference in the propensity to form intra-ring checks, a GC/MS-based global metabolic profiling technique was employed to demonstrate that metabolomics can be used to accurately identify the checking phenotype. Metabolic profiling coupled with statistical tests was then used to develop models with greater than 90% efficiency to predict the intra-ring checking phenotype. Moreover, an inspection of unique metabolites contributing to the models indicated that coniferin, which is often found as a storage compound in rays, is a strong indicator of intra-ring checking, and indeed those genotypes that displayed the propensity to check inherently had a greater number of ray cells per unit area.

Altered functional brain dynamics in chromosome 22q11.2 deletion syndrome during facial affect processing

Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a multisystem disorder associated with multiple congenital anomalies, variable medical features, and neurodevelopmental differences resulting in diverse psychiatric phenotypes, including marked deficits in facial memory and social cognition. Neuroimaging in individuals with 22q11.2DS has revealed differences relative to matched controls in BOLD fMRI activation during facial affect processing tasks. However, time-varying interactions between brain areas during facial affect processing have not yet been studied with BOLD fMRI in 22q11.2DS. We applied constrained principal component analysis to identify temporally overlapping brain activation patterns from BOLD fMRI data acquired during an emotion identification task from 58 individuals with 22q11.2DS and 58 age-, race-, and sex-matched healthy controls. Delayed frontal-motor feedback signals were diminished in individuals with 22q11.2DS, as were delayed emotional memory signals engaging amygdala, hippocampus, and entorhinal cortex. Early task-related engagement of motor and visual cortices and salience-related insular activation were relatively preserved in 22q11.2DS. Insular activation was associated with task performance within the 22q11.2DS sample. Differences in cortical surface area, but not cortical thickness, showed spatial alignment with an activation pattern associated with face processing. These findings suggest that relative to matched controls, primary visual processing and insular function are relatively intact in individuals with 22q11.22DS, while motor feedback, face processing, and emotional memory processes are more affected. Such insights may help inform potential interventional targets and enhance the specificity of neuroimaging indices of cognitive dysfunction in 22q11.2DS.

The RNA-binding protein RBP45D of Arabidopis plays a role in epigenetic control of flowering time and DCL3-independent RNA-directed DNA methylation

RNA-directed DNA methylation (RdDM) helps to defend plants against invasive nucleic acids. In the canonical form of RdDM, 24-nt small interfering RNAs (siRNAs) are produced by DICER-LIKE 3 (DCL3). Here, we describe the Arabidopsis thaliana prors1 (LUC) transgenic system, in which transcriptional gene silencing (TGS) is independent of DLC3. A forward genetics screen performed with this system identified both known components of RdDM, and the RNA-binding protein RBP45D. RBP45D promotes DNA methylation, and its loss delays flowering, especially at high temperature, presumably mediated by elevated FLC levels. RBP45D is localized to the nucleus, where it is associated with snRNAs and snoRNAs. RBP45D maintains siRNA production originating from the LUC transgene, but does not alter mRNA levels or affect processing of transcripts of known RdDM genes. We suggest that RBPD45 facilitates DCL3-independent siRNA production by stabilising either the precursor RNA or the as yet unidentified slicer protein.

Alprazolam modulates persistence energy during emotion processing in first-degree relatives of individuals with schizophrenia: a network control study

Schizophrenia is marked by deficits in facial affect processing associated with abnormalities in GABAergic circuitry, deficits also found in first-degree relatives. Facial affect processing involves a distributed network of brain regions including limbic regions like amygdala and visual processing areas like fusiform cortex. Pharmacological modulation of GABAergic circuitry using benzodiazepines like alprazolam can be useful for studying this facial affect processing network and associated GABAergic abnormalities in schizophrenia. Here, we use pharmacological modulation and computational modeling to study the contribution of GABAergic abnormalities toward emotion processing deficits in schizophrenia. Specifically, we apply principles from network control theory to model persistence energy – the control energy required to maintain brain activation states – during emotion identification and recall tasks, with and without administration of alprazolam, in a sample of first-degree relatives and healthy controls. Here, persistence energy quantifies the magnitude of theoretical external inputs during the task. We find that alprazolam increases persistence energy in relatives but not in controls during threatening face processing, suggesting a compensatory mechanism given the relative absence of behavioral abnormalities in this sample of unaffected relatives. Further, we demonstrate that regions in the fusiform and occipital cortices are important for facilitating state transitions during facial affect processing. Finally, we uncover spatial relationships (i) between regional variation in differential control energy (alprazolam versus placebo) and (ii) both serotonin and dopamine neurotransmitter systems, indicating that alprazolam may exert its effects by altering neuromodulatory systems. Together, these findings reveal differences in emotion-processing circuitry associated with genetic vulnerability to schizophrenia.

EXPRESS: The effect of early list manipulations on the DRM illusion

The Deese-Roediger-McDermott (DRM) paradigm is widely used to study false memory in the laboratory. It tests memory for lists of semantically related words (correct list item memories) and their non-presented associates (false lure memories). Evidence suggests that early items in DRM lists could make an especially significant contribution to false memories of lures, as they may critically influence the underlying associative activation and/or gist extraction processes. The present study tested this suggestion by using two manipulations that were intended to affect processing of early DRM list items. The first was interpolation of a semantically unrelated distractor item among the list items (Experiments 1 and 2). The second was arranging for these items to be either the strongest or weakest associates of the lure (Experiment 2). In Experiment 1, a distractor item reduced both list item and lure recall when presented early in a DRM list, but selectively disrupted list item recall when presented late in the list. In Experiment 2, arranging for the early list items to be the weakest associates of the lure reduced false recall of the lure but had no effect on list item recall. The findings are discussed with respect to theories that explain false memory in the DRM protocol, including fuzzy trace theory (FTT) and activation monitoring theory (AMT). They are also discussed with respect to general theories of memory and the potential role of category/context information in generating false memories.

Semantic as well as referential relevance facilitates the processing of referring expressions.

A range of studies investigating how overspecified referring expressions (e.g., the stripy cup to describe a single cup) affect referent identification have found it to slow identification, speed it up, or yield no effect on processing speed. To date, these studies have all used adjectives that are semantically arbitrary within the sentential context.In addition to the standard ‘informativeness’ design that manipulates the presence of contrast sets, we controlled the semantic relevance of adjectives in discourse to reveal whether overspecifying adjectives would affect processing when relevant to the context (fed the hungry rabbit) compared to when they are not (tickled the hungry rabbit). Using a self-paced reading paradigm with a sample of adult participants (N=31), we found that overspecified noun phrases were read more slowly than those that distinguished a member of a contrast set. Importantly, this penalty was mitigated when adjectives were semantically relevant.Contrary to classical approaches, we show that modifiers do not necessarily presuppose a set, and that referential and semantic information is integrated rapidly in pragmatic processing. Our data support Fukumura and van Gompel’s (2017) meaning-based redundancy hypothesis, which predicts that it is the specific semantic representation of the overspecifying adjective that determines whether a penalty is incurred, rather than generic Gricean expectations. We extend this account using a novel experimental design.

Neural effects of antidepressant medication and psychological treatments: a quantitative synthesis across three meta-analyses

Background Influential theories predict that antidepressant medication and psychological therapies evoke distinct neural changes. Aims To test the convergence and divergence of antidepressant- and psychotherapy-evoked neural changes, and their overlap with the brain's affect network. Method We employed a quantitative synthesis of three meta-analyses (n = 4206). First, we assessed the common and distinct neural changes evoked by antidepressant medication and psychotherapy, by contrasting two comparable meta-analyses reporting the neural effects of these treatments. Both meta-analyses included patients with affective disorders, including major depressive disorder, generalised anxiety disorder and panic disorder. The majority were assessed using negative-valence tasks during neuroimaging. Next, we assessed whether the neural changes evoked by antidepressants and psychotherapy overlapped with the brain's affect network, using data from a third meta-analysis of affect-based neural activation. Results Neural changes from psychotherapy and antidepressant medication did not significantly converge on any region. Antidepressants evoked neural changes in the amygdala, whereas psychotherapy evoked anatomically distinct changes in the medial prefrontal cortex. Both psychotherapy- and antidepressant-related changes separately converged on regions of the affect network. Conclusions This supports the notion of treatment-specific brain effects of antidepressants and psychotherapy. Both treatments induce changes in the affect network, but our results suggest that their effects on affect processing occur via distinct proximal neurocognitive mechanisms of action.