Tonoplast and Peroxisome Targeting of γ-tocopherol N-methyltransferase Homologs Involved in the Synthesis of Monoterpene Indole Alkaloids.

Many plant species from the Apocynaceae, Loganiaceae and Rubiaceae families evolved a specialized metabolism leading to the synthesis of a broad palette of monoterpene indole alkaloids (MIAs). These compounds are believed to constitute a cornerstone of the plant chemical arsenal but above all several MIAs display pharmacological properties that have been exploited for decades by humans to treat various diseases. It is established that MIAs are produced in planta due to complex biosynthetic pathways engaging a multitude of specialized enzymes but also a complex tissue and subcellular organization. In this context, N-methyltransferases (NMTs) represent an important family of enzymes indispensable for MIA biosynthesis but their characterization has always remained challenging. In particular, little is known about the subcellular localization of NMTs in MIA-producing plants. Here, we performed an extensive analysis on the subcellular localization of NMTs from four distinct medicinal plants but also experimentally validated that two putative NMTs from Catharanthus roseus exhibit NMT activity. Apart from providing unprecedented data regarding the targeting of these enzymes in planta, our results point out an additional layer of complexity to the subcellular organization of the MIA biosynthetic pathway by introducing tonoplast and peroxisome as new actors of the final steps of MIA biosynthesis.

Ketamine as the anaesthetic for electroconvulsive therapy: the KANECT randomised controlled trial - CORRIGENDUM.

This notice describes a correction to the above mentioned paper.

Ketamine as the anaesthetic for electroconvulsive therapy: the KANECT randomised controlled trial.

BackgroundKetamine has recently become an agent of interest as an acute treatment for severe depression and as the anaesthetic for electroconvulsive therapy (ECT). Subanaesthetic doses result in an acute reduction in depression severity while evidence is equivocal for this antidepressant effect with anaesthetic or adjuvant doses. Recent systematic reviews call for high-quality evidence from further randomised controlled trials (RCTs).AimsTo establish if ketamine as the anaesthetic for ECT results in fewer ECT treatments, improvements in depression severity ratings and less memory impairment than the standard anaesthetic.MethodDouble-blind, parallel-design, RCT of intravenous ketamine (up to 2 mg/kg) with an active comparator, intravenous propofol (up to 2.5 mg/kg), as the anaesthetic for ECT in patients receiving ECT for major depression on an informal basis. (Trial registration: European Clinical Trials Database (EudraCT): 2011-000396-14 and clinicalTrials.gov: NCT01306760)ResultsNo significant differences were found on any outcome measure during, at the end of or 1 month following the ECT course.ConclusionsKetamine as an anaesthetic does not enhance the efficacy of ECT.

Differences in Cognitive Outcomes After ECT Depending on BDNF and COMT Polymorphisms.

OBJECTIVE: The study aimed to explore cognitive outcomes after electroconvulsive therapy (ECT) depending on which version of common single nucleotide polymorphisms the patient expressed for brain-derived neurotrophic factor (BDNF) and catechol-O-methyltransferase (COMT). METHODS: A total of 87 patients from the clinical ECT service in Aberdeen, Scotland, were included in the study. Cognitive function testing (using Spatial Recognition Memory task from the Cambridge Neuropsychological Test Automated Battery and Mini-Mental State Examination) and mood ratings (Montgomery-Åsberg Depression Rating Scale) were performed before ECT, after 4 treatments, at the end of ECT and 1 and 3 months after the end of treatment. These scores were compared depending on BDNF and COMT variant at each time point using the Student t test and using a time series generalized least squares random effects model. RESULTS: No differences were found between the val and met versions of the BDNF or COMT polymorphism in either cognitive or mood outcomes at any time point during ECT treatment or up to 3 months of follow-up. CONCLUSIONS: This study did not detect significant differences in cognitive or mood outcomes between patients who have the val66val or met versions of the BDNF polymorphism. Our results suggest that these polymorphisms will not be helpful in clinical practice for predicting cognitive outcomes after ECT.

Electroconvulsive therapy reduces frontal cortical connectivity in severe depressive disorder.

To date, electroconvulsive therapy (ECT) is the most potent treatment in severe depression. Although ECT has been successfully applied in clinical practice for over 70 years, the underlying mechanisms of action remain unclear. We used functional MRI and a unique data-driven analysis approach to examine functional connectivity in the brain before and after ECT treatment. Our results show that ECT has lasting effects on the functional architecture of the brain. A comparison of pre- and posttreatment functional connectivity data in a group of nine patients revealed a significant cluster of voxels in and around the left dorsolateral prefrontal cortical region (Brodmann areas 44, 45, and 46), where the average global functional connectivity was considerably decreased after ECT treatment (P < 0.05, family-wise error-corrected). This decrease in functional connectivity was accompanied by a significant improvement (P < 0.001) in depressive symptoms; the patients' mean scores on the Montgomery Asberg Depression Rating Scale pre- and posttreatment were 36.4 (SD = 4.9) and 10.7 (SD = 9.6), respectively. The findings reported here add weight to the emerging "hyperconnectivity hypothesis" in depression and support the proposal that increased connectivity may constitute both a biomarker for mood disorder and a potential therapeutic target.

Anticonvulsant Mechanisms of Electroconvulsive Therapy and Relation to Therapeutic Efficacy.

BACKGROUND: Electroconvulsive therapy (ECT) is held to confer anticonvulsant effects, although the role of rise in seizure threshold upon clinical effect is uncertain. This study investigated the relationship in a large, consecutive, retrospective sample of patients receiving ECT in Aberdeen. We have tested the hypotheses of previous authors to further examine the relationship between seizure and therapeutic effect as well as discuss the potential underlying neurobiological mechanisms. METHODS: All patients receiving ECT at the Royal Cornhill Hospital between 2000 and the end of 2008 were identified from the Scottish ECT Accreditation Network. Electroconvulsive therapy was administered twice weekly with a bifrontotemporal electrode placement using routine dosage schedules. Data were gathered from the Scottish ECT Accreditation Network and case notes regarding ECT course and clinical effect. RESULTS: The seizure threshold increased in 219 (94.4%) patients, stayed the same in 13 (5.6%) patients, and decreased in 0 patient (n = 232). No significant relationship was present between change in seizure threshold and change in Montgomery-Asberg Depression Rating Scale score (P = 0.39; Kendall τ b r = 0.047; n = 182), although responders did display greater increase in seizure threshold than nonresponders. CONCLUSIONS: Electroconvulsive therapy confers anticonvulsant effects in a consecutive sample of real-life patients. Neither initial seizure threshold nor magnitude of seizure threshold increase is a predictor of clinical response to ECT. A rise in seizure threshold is not essential for therapeutic effect but may represent an important marker of underlying neuronal state. The evidence reviewed in this article supports a link between neuroplastic effects of ECT and the evidenced rise in seizure threshold.

Socioeconomic status of patients receiving electroconvulsive therapy.

This study describes the relationship between socioeconomic deprivation and electroconvulsive therapy (ECT) prescription and outcomes. Two research questions are addressed in this study: (1) Does the rate of ECT prescription increase with deprivation? and (2) Does deprivation influence ECT outcomes? Electroconvulsive therapy outcomes, of consecutive patients from Aberdeen, were compared across socioeconomic groups determined by the Scottish Index of Multiple Deprivation (SIMD) quintiles. A primary care sample, invited to complete the Hospital Anxiety and Depression Scale (HADS), was used for comparison. The proportion of patients in the most affluent quintile (32%) was greater than that in the least affluent (9%): this reflects the distribution of the local population, unlike the prevalence of depressive disorder, as demonstrated in our primary care group. Severity of depressive symptoms in patients receiving ECT was no different across the socioeconomic groups: before ECT (χ = 8.056; df = 4; P = 0.09), after ECT (χ = 6.035; df = 4; P = 0.197); nor was the total change in score (χ = 4.367; df = 4; P = 0.359). There were no differences among the SIMD quintiles for the number of ECT treatments administered (χ = 6.076; df = 4; P = 0.194) or the number of courses of ECT each patient had during contact with the service (χ = 6.505; df = 4; P = 0.164).Socioeconomic deprivation has no effect on the rate of ECT prescription or treatment outcomes despite a higher proportion of patients with severe depressive symptoms in the least affluent groups in a local community sample.

A Rapid and Efficient Vacuum-Based Agroinfiltration Protocol for Transient Gene Overexpression in Leaves of Catharanthus roseus.

Functional genomics analyses in planta can be hampered in non-model plants that are recalcitrant to the genetic transformation such as the medicinal plant Catharanthus roseus (Apocynaceae). No stable transformation and regeneration of plantlets have been achieved with a high efficiency in this plant to date. In addition, while virus-mediated transient gene silencing has been reported a decade ago in C. roseus, tools for transient overexpression remain scarce. Here, we describe an efficient and reliable methodology for transiently overexpressing any gene of interest in C. roseus leaves. This protocol combines a vacuum-based Agroinfiltration approach and the high translational efficiency of a deconstructed virus-based binary vector (pEAQ-HT). The described methodology is robust, easy to perform, and results in high amount of transient expression in C. roseus. This protocol is expected to serve as valuable tool to enhance the in planta characterization of gene functions or even transiently knock-in novel enzymatic activities.

Efficient Terpene Production by Marine Thraustochytrids: Shedding Light on the Thermodynamic Driving Force.

Terpenoids, such as squalene, are valuable compounds for cosmetic and drug industries, the supply of which is often limited by natural sources. Alternative production strategies have been investigated for decades but remain challenging due to low yields. In a recent study, Zhang and coworkers (A. Zhang, K. Mernitz, C. Wu, W. Xiong, et al., mBio 12:e0088121, 2021, https://doi.org/10.1128/mBio.00881-21) report the potential use of marine thraustochytrid metabolic thermodynamics in effective terpene engineering. Through comparative proteomics and metabolomics, as well as thermodynamic modeling, the authors demonstrated sodium-induced changes in thraustochytrid metabolism leading to a twofold increase in squalene accumulation. The differential abundances of the metabolic enzymes and metabolites, as well as higher respiration, indicated the metabolic shift from carbohydrate to lipid oxidation and increased ATP input to the mevalonate pathway and squalene synthesis. This breakthrough provides new important insights into microbial terpene metabolic engineering but above all displays thermodynamics as a valuable tool in metabolic engineering.

Exploiting Spermidine N-Hydroxycinnamoyltransferase Diversity and Substrate Promiscuity to Produce Various Trihydroxycinnamoyl Spermidines and Analogues in Engineered Yeast.

Trihydroxycinnamoyl spermidines (THCSpd) are plant specialized metabolites with promising pharmacological activities as antifungals, antibacterial, antiviral, and antidepressant drugs. However, their characterization and potential pharmaceutical exploitation are greatly impaired by the sourcing of these compounds, restricted to the pollen of core Eudicot plant species. In this work, we developed a precursor-directed biosynthesis of THCSpd in yeast using a dual enzymatic system based on 4-coumarate-CoA ligases (4CL) and spermidine N-hydroxycinnamoyltransferases (SHT). The system relies on the yeast endogenous spermidine pool and only requires hydroxycinnamic acids as exogenous precursors. By exploring 4CL isoforms and SHT diversity among plants, we have driven the production of 8 natural THCSpd, using single or mixed hydroxycinnamic acid precursors. Substrate promiscuities of 4CL and SHT were genuinely exploited to produce 8 new-to-nature THCSpd from exotic hydroxycinnamic and dihydrohydroxycinnamic acids, together with 3 new-to-nature THCSpd containing halogenated hydroxycinnamoyl moieties. In this work, we established a versatile and modular biotechnological production platform allowing the tailor-made THCSpd synthesis, constituting pioneer metabolic engineering for access to these valuable natural products.

Growth of white matter in the adolescent brain: role of testosterone and androgen receptor.

The growth of white matter during human adolescence shows a striking sexual dimorphism; the volume of white matter increases with age slightly in girls and steeply in boys. Here, we provide evidence supporting the role of androgen receptor (AR) in mediating the effect of testosterone on white matter. In a large sample of typically developing adolescents (n = 408, 204 males), we used magnetic resonance imaging and acquired T1-weighted and magnetization transfer ratio (MTR) images. We also measured plasma levels of testosterone and genotyped a functional polymorphism in the AR gene, namely the number of CAG repeats in exon 1 believed to be inversely proportional to the AR transcriptional activity. We found that the testosterone-related increase of white-matter volume was stronger in male adolescents with the lower versus higher number of CAG repeats in the AR gene, with testosterone explaining, respectively, 26 and 8% of variance in the volume. The MTR results suggest that this growth is not related to myelination; the MTR decreased with age in male adolescents. We speculate that testosterone affects axonal caliber rather than the thickness of the myelin sheath.

Schizophrenia illness severity is associated with reduced loss aversion.

Loss aversion, whereby losses weigh more heavily than equal-sized gains, has been demonstrated in many decision-making settings. Previous research has suggested reduced loss aversion in schizophrenia, but with little evidence of a link between loss aversion and schizophrenia illness severity. In this study, 20 individuals with schizophrenia and 16 control participants, matched by age and sex, played two versions of the Iterated Prisoners' Dilemma, one version with only positive payoffs and another version in which negative payoffs were possible, with the second version being derived from the first by subtracting a constant value from all payoffs. The control group demonstrated significantly lower cooperation rates under negative payoffs, compared with the version with only positive payoffs, indicative of loss aversion. The patient group on average showed no loss aversion response. Moreover, the extent of loss aversion in patients was found to be negatively correlated with schizophrenia illness severity, with less ill patients showing loss aversion more similar to controls. Results were found to be robust to the inclusion of potential confounding factors as covariates within rigorous probit regression analyses. Reduced loss aversion is a feature of schizophrenia and related to illness severity.

Hormonal contraceptives, menstrual cycle and brain response to faces.

Both behavioral and neuroimaging evidence support a female advantage in the perception of human faces. Here we explored the possibility that this relationship may be partially mediated by female sex hormones by investigating the relationship between the brain's response to faces and the use of oral contraceptives, as well as the phase of the menstrual cycle. First, functional magnetic resonance images were acquired in 20 young women [10 freely cycling and 10 taking oral contraception (OC)] during two phases of their cycle: mid-cycle and menstruation. We found stronger neural responses to faces in the right fusiform face area (FFA) in women taking oral contraceptives (vs freely cycling women) and during mid-cycle (vs menstruation) in both groups. Mean blood oxygenation level-dependent response in both left and right FFA increased as function of the duration of OC use. Next, this relationship between the use of OC and FFA response was replicated in an independent sample of 110 adolescent girls. Finally in a parallel behavioral study carried out in another sample of women, we found no evidence of differences in the pattern of eye movements while viewing faces between freely cycling women vs those taking oral contraceptives. The imaging findings might indicate enhanced processing of social cues in women taking OC and women during mid-cycle.

A comparison of ECT dosing methods using a clinical sample.

BACKGROUND: Several methods have been used to determine ECT dose based on formulae, protocols or fixed-dosing. This study aims to explore the relative utility of these ECT dosing methods. METHODS: A sample of ECT patients from Aberdeen was analysed. Seizure thresholds derived empirically were used to calculate the proportions of patients who would have had a therapeutic stimulus had Half-Age or a fixed-dosing method (200 mC for those <65 years old and 250 mC for those >65 years old) been used. RESULTS: 62 patients were included. Initial seizure threshold varied 6 fold across the sample. Using the Half Age method 19.4% would have had a therapeutic seizure at first stimulation compared with 61.3% using an age based fixed protocol and 0% using the Royal College recommended dose titration method. Half Age and Fixed Dosing would have significantly (p<.0001) reduced the number of stimulations, the cumulative electrical dose delivered, the complexity of the procedure and the number of treatment sessions required. LIMITATIONS: This study applies only to patients receiving bilateral ECT for a major depressive episode. It uses a pragmatic design to explore a common clinical issue. This allows the feasibility of further work to be explored as this would be precluded by ethical concerns otherwise. It also uses ECT parameters which are common in UK practice which may limit its applicability internationally. CONCLUSIONS: Age based fixed-dosing would simplify the ECT process and result in more patients receiving effective treatment at first stimulation.

Magnetic resonance imaging as a tool for in vivo and ex vivo anatomical phenotyping in experimental genetic models.

This article describes a suite of computational approaches suitable for deriving various quantitative phenotypes from structural magnetic resonance (MR) images obtained in rodents and used subsequently in genetic studies of complex traits. We begin by introducing the basic principles of genetic studies of complex traits in experimental models. We then illustrate the use of MR-based computational anatomy in vivo and ex vivo, and in combination with histology. This work was carried out in two inbred strains of rats, namely spontaneously hypertensive rats and Brown Norway rats; these are parental strains of the only existing panel of recombinant inbred strains of rats. The rats were scanned in vivo at two time points (at 8 and 12 weeks of age) and ex vivo (at 12 weeks of age). We describe between-strain differences and across-time changes in brain and kidney volumes, as well as regional variations in brain structure using surface- and deformation-based approaches. We conclude by discussing the power of the population-based computational analysis of MR images, and their fusion with histology, in studies of complex traits.

The expression of the clock protein PER2 in the limbic forebrain is modulated by the estrous cycle.

Daily behavioral and physiological rhythms are linked to circadian oscillations of clock genes in the brain and periphery that are synchronized by the master clock in the suprachiasmatic nucleus. In addition, there are a number of inputs that can influence circadian oscillations in clock gene expression in a tissue-specific manner. Here we identify an influence on the circadian oscillation of the clock protein PER2, endogenous changes in ovarian steroids, within two nuclei of the limbic forebrain: the oval nucleus of the bed nucleus of the stria terminalis and central nucleus of the amygdala. We show that the daily rhythm of PER2 expression within these nuclei but not in the suprachiasmatic nucleus, dentate gyrus, or basolateral amygdala is blunted in the metestrus and diestrus phases of the estrus cycle. The blunting of the PER2 rhythm at these phases of the cycle is abolished by ovariectomy and restored by phasic estrogen replacement suggesting that fluctuations in estrogen levels or their sequelae are necessary to produce these effects. The finding that fluctuations in ovarian hormones have area-specific effects on clock gene expression in the brain introduces a new level of organizational complexity in the control of circadian rhythms of behavior and physiology.