Fitness trade-offs and the origins of endosymbiosis.

Endosymbiosis drives evolutionary innovation and underpins the function of diverse ecosystems. The mechanistic origins of symbioses, however, remain unclear, in part because early evolutionary events are obscured by subsequent evolution and genetic drift. This Essay highlights how experimental studies of facultative, host-switched, and synthetic symbioses are revealing the important role of fitness trade-offs between within-host and free-living niches during the early-stage evolution of new symbiotic associations. The mutational targets underpinning such trade-offs are commonly regulatory genes, such that single mutations have major phenotypic effects on multiple traits, thus enabling and reinforcing the transition to a symbiotic lifestyle.

A Rapid Access Brief Psychotherapy Intervention to Respond to Healthcare Workers in Ontario Whose Mental Health was Negatively Impacted During the COVID-19 Pandemic.

OBJECTIVE: Although the coronavirus disease 2019 (COVID-19) pandemic has had widespread negative impacts on the mental health of healthcare workers (HCWs), there has been little research on psychological interventions during the pandemic for this population. The current study examines whether a brief coping-focused treatment intervention delivered in a virtual individual format would be associated with positive changes in Canadian HCWs' mental health during the pandemic. METHOD: Three hundred and thirty-three HCWs receiving the intervention at 3 large specialty tertiary care hospitals in Ontario, Canada, completed measures of anxiety, depression, perceived stress, work/social impairment, insomnia and fear of COVID-19. After completing treatment, HCWs rated their satisfaction with the treatment. RESULTS: The intervention was associated with large effect size improvements in anxiety, depression, perceived stress, insomnia and fear of COVID-19, and moderate effect size improvements in work/social impairment. At treatment session 1, prior mental health diagnosis and treatment were both significantly correlated with depression, anxiety, and work/social impairment scores. Secondary analyses of data from one of the sites revealed that treatment-related changes in anxiety, depression, perceived stress and work/social impairment were independent of age, gender, occupational setting, profession and the presence of a previous mental health diagnosis or treatment, with the exception that nurses improved at a slightly greater rate than other professions in terms of work/social impairment. HCWs were highly satisfied with the treatment. CONCLUSIONS: A large number of HCWs experiencing significant distress at baseline self-referred for assistance. Timely and flexible access to a brief virtual coping-focused intervention was associated with improvements in symptoms and impairment, and treatment response was largely unrelated to demographic or professional characteristics. Short-term psychological interventions for HCWs during a pandemic may have a highly positive impact given their association with improvement in various aspects of HCWs' mental health improvement.

Online versus in-person delivery of cognitive behaviour therapy for obsessive compulsive disorder: An examination of effectiveness.

Cognitive behavioural therapy (CBT) including exposure and response prevention is the first-line psychological treatment for obsessive compulsive disorder (OCD). Given changes in the clinical landscape, there are increasing efforts to evaluate its effectiveness in online contexts. Mirroring the traditional in-person delivery, few studies have assessed the role of therapist-guided, manual-based CBT for OCD delivered in real-time via videoconferencing methods. The present study sought to fill this gap by comparing in-person and online delivery of group-based CBT for the treatment of OCD. A convenience sample of participants with moderate to severe OCD (n = 144) were recruited from a naturalistic database from two large OCD specialty assessment and treatment centres. Patients received group-based CBT that was provided in-person (pre-COVID-19 pandemic; March 2018 to March 2020) or online via videoconferencing (during the COVID-19 pandemic; March 2020 to April 2021). In both delivery methods, treatment consisted of 2-h weekly sessions led by trained clinicians. Analyses revealed that, regardless of treatment modality, both in-person and online groups demonstrated significant, reliable, and statistically equivalent improvements in OCD symptoms post-treatment. Videoconferenced, clinician-led CBT may be a promising alternative to in-person delivery for those with moderate to severe OCD symptoms.

Face-to-face versus Video Teleconference Group Cognitive Behavioural Therapy for Anxiety and Related Disorders: A Preliminary Comparison.

OBJECTIVE: Telehealth is being increasingly incorporated into the delivery of mental health care and has received widespread attention during the COVID-19 pandemic for its ability to facilitate care during physical distancing restrictions. Videoconferencing is a common telehealth modality for delivering psychotherapy and has demonstrated similar outcomes to those of face-to-face therapy. Cognitive behavioural therapy (CBT) is the most common psychotherapy evaluated across various telehealth modalities; however, studies on CBT delivered via videoconference, particularly in a group therapy format, are lacking. Further, little research exists on videoconference group CBT for anxiety disorders. Accordingly, the present study compared the outcomes of group CBT for anxiety and related disorders delivered via videoconference versus face-to-face. METHOD: Using a non-randomized design, data on attendance, dropout, clinical outcomes, and functional impairment were collected from 413 adult outpatients of a tertiary care anxiety disorders clinic who attended a CBT group for panic disorder/agoraphobia, social anxiety disorder, generalized anxiety disorder (GAD), or obsessive-compulsive disorder delivered either face-to-face (pre-COVID-19 pandemic) or via videoconference (since the onset of COVID-19 pandemic). Outcomes were assessed using well-validated self-report measures. Data were collected pre-treatment, across 12 weekly sessions, and post-treatment. Intent-to-treat analyses were applied to symptom outcome measures. RESULTS: Face-to-face CBT conferred only a slight benefit over videoconference CBT for symptom outcomes across all groups, but when assessed individually, only the GAD group showed greater symptom improvement in the face-to-face format. Effect sizes for significant differences between the delivery formats were small. Participants in videoconference groups tended to have slightly higher attendance rates in some instances, whereas functional improvement and treatment dropout were comparable across the delivery formats. CONCLUSIONS: Results provide preliminary evidence that videoconference group CBT for anxiety and related disorders may be a promising and effective alternative to face-to-face CBT. Additional research is needed to establish equivalence between these delivery formats.

Sensitivity and specificity of the Posttraumatic Stress Disorder Checklist for DSM-5 in a Canadian psychiatric outpatient sample.

The Posttraumatic Stress Disorder (PTSD) Checklist for DSM-5 (PCL-5) is a widely used, self-report measure that is employed to assess PTSD symptom severity and determine the presence of probable PTSD in various trauma-exposed populations. The PCL-5 is often administered in clinical settings as a screening tool for PTSD, with a suggested cutoff score of 33 indicating a probable PTSD diagnosis. Recent research indicates that a higher cutoff may be required in psychiatric samples. In the present study, we aimed to determine the sensitivity and specificity of the PCL-5 in a Canadian outpatient psychiatric sample and establish an optimal cutoff score for detecting probable PTSD in this sample. Participants were 673 individuals who reported a history of trauma exposure and were assessed using a semistructured interview and self-report measures. Individuals diagnosed with PTSD (N = 193) reported a mean PCL-5 score of 56.57, whereas individuals without PTSD (N = 480) reported a mean score of 33.56. A score of 45 was determined to be the optimal cutoff score in this sample, balancing sensitivity and specificity while detecting a probable diagnosis of PTSD. Consistent with findings in other psychiatric samples, these findings indicate that in an outpatient psychiatric sample with a history of exposure to a variety of trauma types, a higher cutoff score is required to determine probable PTSD. In addition, given the estimated rate of false positives even with a higher cutoff, follow-up diagnostic assessments are recommended.

Phytase catalysis of dephosphorylation studied using isothermal titration calorimetry and electrospray ionization time-of-flight mass spectroscopy.

Phytases are important commercial enzymes that catalyze the dephosphorylation of myo-inositol hexakisphosphate (phytate) to its lower inositol phosphate (IP) esters, IP6 to IP1. Digestion of phytate by Citrobacter braakii 6-phytase deviates significantly from monophasic Michaelis-Menten kinetics. Analysis of phytate digestion using isothermal titration calorimetry (ITC) using the single injection method produced a thermogram with two peaks consistent with two periods of high enzyme activity. Continuous-flow electrospray ionization time-of-flight mass spectroscopy (ESI-ToF-MS) provided real-time analysis of phytase catalysis. It was able to show that the first two cleavage steps were rapid and concurrent but the third cleavage step from IP4 to IP3 was slow. The third (IP4 to IP3), fourth (IP3 to IP2) and fifth (IP2 to IP1) cleavages were effectively sequential due to the preferred association of the more phosphorylated species with the phytase catalytic site. This created a bottleneck during the cleavage of IP4 to IP3 until the point at which IP4 was exhausted and was followed by the rapid cleavage of IP3 to IP2, which was observed as the second peak in the ITC thermogram. This work illustrates the importance of an orthogonal approach when studying non-specific or complex enzyme catalyzed reactions.

Subjective Experiences of Driving Cessation and Dementia: A Meta-Synthesis of Qualitative Literature.

Objectives: To review qualitative research on the specific challenges and strategies that relate to driving cessation for older adults with dementia, from the perspectives of key informant groups.Method: A meta-synthesis of qualitative studies was conducted. Structured inclusion criteria were applied to screen 616 titles and abstracts, and 9 qualitative studies were included, published from 2002 to 2016. Descriptive themes were identified using content analysis and synthesized to generate analytic themes.Results: The study samples and methodologies represented a diverse range. Cross-cutting themes on experiences of driving cessation for people with dementia are the: importance of open communication and autonomy in decision-making, and advanced planning to connect people with resources; significance of relationships; importance of providing support for the impact of cessation on identity and emotional wellbeing; and benefit of individualizing supportive approaches.Conclusion: This review identifies some important areas for consideration when designing supportive programs to address driving.Clinical Implications: Interventions to support driving cessation for people with dementia should prioritize support for communication, advanced planning, and emotional effects of stopping driving.

Functional complementarity of ancient plant-fungal mutualisms: contrasting nitrogen, phosphorus and carbon exchanges between Mucoromycotina and Glomeromycotina fungal symbionts of liverworts.

Liverworts, which are amongst the earliest divergent plant lineages and important ecosystem pioneers, often form nutritional mutualisms with arbuscular mycorrhiza-forming Glomeromycotina and fine-root endophytic Mucoromycotina fungi, both of which coevolved with early land plants. Some liverworts, in common with many later divergent plants, harbour both fungal groups, suggesting these fungi may complementarily improve plant access to different soil nutrients. We tested this hypothesis by growing liverworts in single and dual fungal partnerships under a modern atmosphere and under 1500 ppm [CO2 ], as experienced by early land plants. Access to soil nutrients via fungal partners was investigated with 15 N-labelled algal necromass and 33 P orthophosphate. Photosynthate allocation to fungi was traced using 14 CO2 . Only Mucoromycotina fungal partners provided liverworts with substantial access to algal 15 N, irrespective of atmospheric CO2 concentration. Both symbionts increased 33 P uptake, but Glomeromycotina were often more effective. Dual partnerships showed complementarity of nutrient pool use and greatest photosynthate allocation to symbiotic fungi. We show there are important functional differences between the plant-fungal symbioses tested, providing new insights into the functional biology of Glomeromycotina and Mucoromycotina fungal groups that form symbioses with plants. This may explain the persistence of the two fungal lineages in symbioses across the evolution of land plants.

Variation and asymmetry in host-symbiont dependence in a microbial symbiosis.

BACKGROUND: Symbiosis is a major source of evolutionary innovation and, by allowing species to exploit new ecological niches, underpins the functioning of ecosystems. The transition from free-living to obligate symbiosis requires the alignment of the partners' fitness interests and the evolution of mutual dependence. While symbiotic taxa are known to vary widely in the extent of host-symbiont dependence, rather less is known about variation within symbiotic associations. RESULTS: Using experiments with the microbial symbiosis between the protist Paramecium bursaria and the alga Chlorella, we show variation between pairings in host-symbiont dependence, encompassing facultative associations, mutual dependence and host dependence upon the symbiont. Facultative associations, that is where both the host and the symbiont were capable of free-living growth, displayed higher symbiotic growth rates and higher per host symbiont loads than those with greater degrees of dependence. CONCLUSIONS: These data show that the Paramecium-Chlorella interaction exists at the boundary between facultative and obligate symbiosis, and further suggest that the host is more likely to evolve dependence than the algal symbiont.

Reducing Stomatal Density in Barley Improves Drought Tolerance without Impacting on Yield.

The epidermal patterning factor (EPF) family of secreted signaling peptides regulate the frequency of stomatal development in model dicot and basal land plant species. Here, we identify and manipulate the expression of a barley (Hordeum vulgare) ortholog and demonstrate that when overexpressed HvEPF1 limits entry to, and progression through, the stomatal development pathway. Despite substantial reductions in leaf gas exchange, barley plants with significantly reduced stomatal density show no reductions in grain yield. In addition, HvEPF1OE barley lines exhibit significantly enhanced water use efficiency, drought tolerance, and soil water conservation properties. Our results demonstrate the potential of manipulating stomatal frequency for the protection and optimization of cereal crop yields under future drier environments.

Psychometric Evaluation of a Revised Scoring Approach for the Children's Saving Inventory in a Canadian Sample of Youth With Obsessive-Compulsive Disorder.

The Children's Saving Inventory (CSI) was introduced in 2011 and is the first parent-rated questionnaire specifically designed to measure the severity of hoarding symptoms in youth. To date, however, no replication studies of the CSI have been published. Additionally, the total CSI score includes several items measuring acquisition, a behavioural dimension that has since been excluded from DSM-5's hoarding disorder criteria. Given these limitations, the primary goal of the present study was to test a modified, DSM-5-consistent, total score of the CSI. Because a confirmatory factor analysis did not support the 2011 four-factor model of the CSI, we reviewed the original CSI and excluded all acquisition items. An exploratory factor analysis yielded a strong three-factor solution (difficulty discarding, Clutter, and distress/impairment) with good reliability and validity for a 15-item version of the CSI. Overall, our results support the use of the 15-item CSI in youth with OCD.

Foundational and Translational Research Opportunities to Improve Plant Health.

Reader Comments | Submit a Comment The white paper reports the deliberations of a workshop focused on biotic challenges to plant health held in Washington, D.C. in September 2016. Ensuring health of food plants is critical to maintaining the quality and productivity of crops and for sustenance of the rapidly growing human population. There is a close linkage between food security and societal stability; however, global food security is threatened by the vulnerability of our agricultural systems to numerous pests, pathogens, weeds, and environmental stresses. These threats are aggravated by climate change, the globalization of agriculture, and an over-reliance on nonsustainable inputs. New analytical and computational technologies are providing unprecedented resolution at a variety of molecular, cellular, organismal, and population scales for crop plants as well as pathogens, pests, beneficial microbes, and weeds. It is now possible to both characterize useful or deleterious variation as well as precisely manipulate it. Data-driven, informed decisions based on knowledge of the variation of biotic challenges and of natural and synthetic variation in crop plants will enable deployment of durable interventions throughout the world. These should be integral, dynamic components of agricultural strategies for sustainable agriculture.

A novel root-to-shoot stomatal response to very high CO2 levels in the soil: electrical, hydraulic and biochemical signalling.

Investigations were undertaken in the context of the potential environmental impact of carbon capture and storage (CCS) transportation in the form of a hypothetical leak of extreme levels of CO2 into the soil environment and subsequent effects on plant physiology. Laboratory studies using purpose built soil chambers, separating and isolating the soil and aerial environments, were used to introduce high levels of CO2 gas exclusively into the rhizosphere. CO2 concentrations greater than 32% in the isolated soil environment revealed a previously unknown whole plant stomatal response. Time course measurements of stomatal conductance (gs ), leaf temperature and leaf abscisic acid (ABA) show strong coupling between all three variables over a specific period (3 h following CO2 gassing) occurring as a result of CO2 -specific detection by roots. The coupling of gs and ABA subsequently breaks down resulting in a rapid and complete loss of turgor in the shoot. Root access to water is severely restricted as evidenced by the inability to counter turgor loss, however, the plant regains some turgor over time. Recovery of full turgor is not achieved over the longer term. Results suggest an immediate perception and whole plant response as changes in measured parameters (leaf temperature, gs and ABA) occur in the shoot, but the response is solely due to detection of very high CO2 concentration at the root/soil interface which results in loss of stomatal regulation and disruption to control over water uptake.

A systematic review of intervention approaches for driving cessation in older adults.

OBJECTIVE: The aim of this project was to review the literature on interventions aimed at facilitating driving cessation in older adults, with and without dementia. METHODS: A literature search was performed using the databases MEDLINE, CINAHL, Cochrane Central, Embase, and PsycINFO, from 1994 to September 2014. Two independent raters screened articles for inclusion and extracted study data. We only included articles if they directly addressed the topic of intervention approaches to facilitate the process of driving cessation in older adults or to support the adaptation of older adults who have had to stop driving and included a control group. RESULTS: Of an initial 477 unique records identified, 111 pertained to driving cessation in older adults, and only three articles were controlled trials of intervention approaches related to driving cessation. One article described an intervention for retired drivers with dementia, while another was aimed at caregivers of drivers with dementia, and the third included retired and retiring drivers without dementia. Outcomes such as reduced depressive symptoms, increased trips out of home, and efficacy in dealing with the driving cessation process were positive, but the specific outcome measures and magnitude of effects varied across studies. CONCLUSIONS: Although the results summarized in this review point toward potentially promising effects of interventions for facilitating driving cessation in older adults, these findings must be interpreted with caution given the significant methodological limitations of the studies, including small samples, participant attrition, lack of blinding, and non-validated outcome measures. Copyright © 2017 John Wiley & Sons, Ltd.

Development of a decision-making tool for reporting drivers with mild dementia and mild cognitive impairment to transportation administrators.

BACKGROUND: Driving in persons with dementia poses risks that must be counterbalanced with the importance of the care for autonomy and mobility. Physicians often find substantial challenges in the assessment and reporting of driving safety for persons with dementia. This paper describes a driving in dementia decision tool (DD-DT) developed to aid physicians in deciding when to report older drivers with either mild dementia or mild cognitive impairment to local transportation administrators. METHODS: A multi-faceted, computerized decision support tool was developed, using a systematic literature and guideline review, expert opinion from an earlier Delphi study, as well as qualitative interviews and focus groups with physicians, caregivers of former drivers with dementia, and transportation administrators. The tool integrates inputs from the physician-user about the patient's clinical and driving history as well as cognitive findings, and it produces a recommendation for reporting to transportation administrators. This recommendation is translated into a customized reporting form for the transportation authority, if applicable, and additional resources are provided for the patient and caregiver. CONCLUSIONS: An innovative approach was needed to develop the DD-DT. The literature and guideline review confirmed the algorithm derived from the earlier Delphi study, and barriers identified in the qualitative research were incorporated into the design of the tool.

Understanding metabolism of arginine in biological systems via MALDI imaging.

Arginine is an important amino acid but has been barely studied in plants. The little research that has been done indicates that the pathways of synthesis are similar to those found in animals and procaryotes. However little is known about the cellular and tissue localization of the amino acid in plants. The research reported in this paper was designed to examine whether MALDI-MSI was sufficiently sensitive to examine the distribution of this amino acid in plant material, and whether the synthetic pathways were co-located. In wheat and orchid roots, the amount of arginine in tissues varies greatly and the pathways for its synthesis were not always detected with the amino acid.

Resolving the 'nitrogen paradox' of arbuscular mycorrhizas: fertilization with organic matter brings considerable benefits for plant nutrition and growth.

Arbuscular mycorrhizal fungi (AMF) can transfer nitrogen (N) to host plants, but the ecological relevance is debated, as total plant N and biomass do not generally increase. The extent to which the symbiosis is mutually beneficial is thought to rely on the stoichiometry of N, phosphorus (P) and carbon (C) availability. While inorganic N fertilization has been shown to elicit strong mutualism, characterized by improved plant and fungal growth and mineral nutrition, similar responses following organic N addition are lacking. Using a compartmented microcosm experiment, we determined the significance to a mycorrhizal plant of placing a (15) N-labelled, nitrogen-rich patch of organic matter in a compartment to which only AMF hyphae had access. Control microcosms denied AMF hyphal access to the patch compartment. When permitted access to the patch compartment, the fungus proliferated extensively in the patch and transferred substantial quantities of N to the plant. Moreover, our data demonstrate that allowing hyphal access to an organic matter patch enhanced total plant N and P contents, with a simultaneous and substantial increase in plant biomass. Furthermore, we demonstrate that organic matter fertilization of arbuscular mycorrhizal plants can foster a mutually beneficial symbiosis based on nitrogen transfer, a phenomenon previously thought irrelevant.

Host control and nutrient trading in a photosynthetic symbiosis.

Photosymbiosis is one of the most important evolutionary trajectories, resulting in the chloroplast and the subsequent development of all complex photosynthetic organisms. The ciliate Paramecium bursaria and the alga Chlorella have a well established and well studied light dependent endosymbiotic relationship. Despite its prominence, there remain many unanswered questions regarding the exact mechanisms of the photosymbiosis. Of particular interest is how a host maintains and manages its symbiont load in response to the allocation of nutrients between itself and its symbionts. Here we construct a detailed mathematical model, parameterised from the literature, that explicitly incorporates nutrient trading within a deterministic model of both partners. The model demonstrates how the symbiotic relationship can manifest as parasitism of the host by the symbionts, mutualism, wherein both partners benefit, or exploitation of the symbionts by the hosts. We show that the precise nature of the photosymbiosis is determined by both environmental conditions (how much light is available for photosynthesis) and the level of control a host has over its symbiont load. Our model provides a framework within which it is possible to pose detailed questions regarding the evolutionary behaviour of this important example of an established light dependent endosymbiosis; we focus on one question in particular, namely the evolution of host control, and show using an adaptive dynamics approach that a moderate level of host control may evolve provided the associated costs are not prohibitive.

Manipulating stomatal density enhances drought tolerance without deleterious effect on nutrient uptake.

Manipulation of stomatal density was investigated as a potential tool for enhancing drought tolerance or nutrient uptake. Drought tolerance and soil water retention were assessed using Arabidopsis epidermal patterning factor mutants manipulated to have increased or decreased stomatal density. Root nutrient uptake via mass flow was monitored under differing plant watering regimes using nitrogen-15 ((15) N) isotope and mass spectrometry. Plants with less than half of their normal complement of stomata, and correspondingly reduced levels of transpiration, conserve soil moisture and are highly drought tolerant but show little or no reduction in shoot nitrogen concentrations especially when water availability is restricted. By contrast, plants with over twice the normal density of stomata have a greater capacity for nitrogen uptake, except when water availability is restricted. We demonstrate the possibility of producing plants with reduced transpiration which have increased drought tolerance, with little or no loss of nutrient uptake. We demonstrate that increasing transpiration can enhance nutrient uptake when water is plentiful.