First Extensive Microscopic Study of Butternut Defense Mechanisms Following Inoculation with the Canker Pathogen Ophiognomonia clavigignenti-juglandacearum Reveals Compartmentalization of Tissue Damage.

Ophiognomonia clavigignenti-juglandacearum endangers the survival of butternut (Juglans cinerea) throughout its native range. While screening for disease resistance, we found that artificial inoculations of 48 butternut seedlings with O. clavigignenti-juglandacearum induced the expression of external symptoms, but only after a period of dormancy. Before dormancy, compartmentalized tissues such as necrophylactic periderms (NPs) and xylem reaction zones (RZs) contributed to limiting pathogen invasion. Phenols were regularly detected in RZs, often in continuity with NPs during wound closure, and confocal microscopy revealed their presence in parenchyma cells, vessel plugs and cell walls. Vessels were blocked with tyloses and gels, particularly those present in RZs. Suberin was also detected in cells formed over the affected xylem by the callus at the inoculation point, in a few tylosis walls, and in longitudinal tubes that formed near NPs. Following dormancy, in all inoculated seedlings but one, defensive barriers were breached by O. clavigignenti-juglandacearum and then additional ones were produced in response to this new invasion. The results of this histopathological study indicate that trees inoculated in selection programs to test butternut canker resistance should go through at least one period of dormancy and that asymptomatic individuals should be dissected to better assess how they defend themselves against O. clavigignenti-juglandacearum.

Cerebrovascular and blood-brain barrier impairments in Huntington's disease: Potential implications for its pathophysiology.

OBJECTIVE: Although the underlying cause of Huntington's disease (HD) is well established, the actual pathophysiological processes involved remain to be fully elucidated. In other proteinopathies such as Alzheimer's and Parkinson's diseases, there is evidence for impairments of the cerebral vasculature as well as the blood-brain barrier (BBB), which have been suggested to contribute to their pathophysiology. We investigated whether similar changes are also present in HD. METHODS: We used 3- and 7-Tesla magnetic resonance imaging as well as postmortem tissue analyses to assess blood vessel impairments in HD patients. Our findings were further investigated in the R6/2 mouse model using in situ cerebral perfusion, histological analysis, Western blotting, as well as transmission and scanning electron microscopy. RESULTS: We found mutant huntingtin protein (mHtt) aggregates to be present in all major components of the neurovascular unit of both R6/2 mice and HD patients. This was accompanied by an increase in blood vessel density, a reduction in blood vessel diameter, as well as BBB leakage in the striatum of R6/2 mice, which correlated with a reduced expression of tight junction-associated proteins and increased numbers of transcytotic vesicles, which occasionally contained mHtt aggregates. We confirmed the existence of similar vascular and BBB changes in HD patients. INTERPRETATION: Taken together, our results provide evidence for alterations in the cerebral vasculature in HD leading to BBB leakage, both in the R6/2 mouse model and in HD patients, a phenomenon that may, in turn, have important pathophysiological implications.

Transformational Leadership and Change: How Leaders Influence Their Followers' Motivation Through Organizational Justice.

In the past decade, the reform of Québec's healthcare establishments has resulted in a reduction in the number of institutions through mergers and closures. In this report, we investigate the consequences of reform by looking at managers' motivations and related mitigating factors. We examine the influence that transformational leaders have on their employees' motivation through organizational justice. Using a survey of 253 healthcare managers, we describe how the positive impact of transformational leadership on motivation is fully mediated via different aspects of organizational justice. The results indicate that while transformational leaders influence each type of organizational justice, followers' motivation is affected primarily by procedural and interpersonal justice and little by distributive justice.

The morphological and molecular changes of brain cells exposed to direct current electric field stimulation.

BACKGROUND: The application of low-intensity direct current electric fields has been experimentally used in the clinic to treat a number of brain disorders, predominantly using transcranial direct current stimulation approaches. However, the cellular and molecular changes induced by such treatment remain largely unknown. METHODS: Here, we tested various intensities of direct current electric fields (0, 25, 50, and 100V/m) in a well-controlled in vitro environment in order to investigate the responses of neurons, microglia, and astrocytes to this type of stimulation. This included morphological assessments of the cells, viability, as well as shape and fiber outgrowth relative to the orientation of the direct current electric field. We also undertook enzyme-linked immunosorbent assays and western immunoblotting to identify which molecular pathways were affected by direct current electric fields. RESULTS: In response to direct current electric field, neurons developed an elongated cell body shape with neurite outgrowth that was associated with a significant increase in growth associated protein-43. Fetal midbrain dopaminergic explants grown in a collagen gel matrix also showed a reorientation of their neurites towards the cathode. BV2 microglial cells adopted distinct morphological changes with an increase in cyclooxygenase-2 expression, but these were dependent on whether they had already been activated with lipopolysaccharide. Finally, astrocytes displayed elongated cell bodies with cellular filopodia that were oriented perpendicularly to the direct current electric field. CONCLUSION: We show that cells of the central nervous system can respond to direct current electric fields both in terms of their morphological shape and molecular expression of certain proteins, and this in turn can help us to begin understand the mechanisms underlying the clinical benefits of direct current electric field.

Strengthening child and youth programs: A look at inter-organizational mentoring strategies.

Community-based non-profit organizations rarely have access to research or evaluation evidence to inform their programs and often lack the capacity to gather or use this information independently. In 2016, Wisdom2Action-a network of knowledge mobilization (KMb) experts, policy makers and service providers across Canada-launched an inter-organizational mentorship program to facilitate the implementation and sharing of best and promising practices within community-based programs for young people. This article outlines the findings from a developmental evaluation of eight mentoring relationships. Drawing on the Promoting Action on Research in Health Sciences (PARiHS) model of KMb, we look at mentoring as a type of facilitation that supports the increased use of evidence and evaluation information by non-profit organizations and identify key themes that support effective organizational mentorship in this sector. Findings reinforce the importance of establishing connected relationships and understanding context in mentoring relationships, creating adaptive and responsive work plans, ensuring consistent communication, and maintaining a focus on capacity-building if knowledge mobilization is to occur.

Variation in stem morphology and movement of amyloplasts in white spruce grown in the weightless environment of the International Space Station.

One-year-old white spruce (Picea glauca) seedlings were studied in microgravity conditions in the International Space Station (ISS) and compared with seedlings grown on Earth. Leaf growth was clearly stimulated in space whereas data suggest a similar trend for the shoots. Needles on the current shoots of ground-based seedlings were more inclined towards the stem base than those of seedlings grown in the ISS. Amyloplasts sedimented in specialized cells of shoots and roots in seedlings grown on Earth while they were distributed at random in similar cells of seedlings tested in the ISS. In shoots, such amyloplasts were found in starch sheath cells located between leaf traces and cortical cells whereas in roots they were constituents of columella cells of the cap. Nuclei were regularly observed just above the sedimented amyloplasts in both organs. It was also frequent to detect vacuoles with phenolic compounds and endoplasmic reticulum (ER) close to the sedimented amyloplasts. The ER was mainly observed just under these amyloplasts. Thus, when amyloplasts sediment, the pressure exerted on the ER, the organelle that can for instance secrete proteins destined for the plasma membrane, might influence their functioning and play a role in signaling pathways involved in gravity-sensing white spruce cells.

A 6374 unigene set corresponding to low abundance transcripts expressed following fertilization in Solanum chacoense Bitt, and characterization of 30 receptor-like kinases.

In order to characterize regulatory genes that are expressed in ovule tissues after fertilization we have undertaken an EST sequencing project in Solanum chacoense, a self-incompatible wild potato species. Two cDNA libraries made from ovule tissues covering embryo development from zygote to late torpedo-stage were constructed and plated at high density on nylon membranes. To decrease EST redundancy and enrich for transcripts corresponding to weakly expressed genes a self-probe subtraction method was used to select the colonies harboring the genes to be sequenced. 7741 good sequences were obtained and, from these, 6374 unigenes were isolated. Thus, the self-probe subtraction resulted in a strong enrichment in singletons, a decrease in the number of clones per contigs, and concomitantly, an enrichment in the total number of unigenes obtained (82%). To gain insights into signal transduction events occurring during embryo development all the receptor-like kinases (or protein receptor kinases) were analyzed by quantitative real-time RT-PCR. Interestingly, 28 out of the 30 RLK isolated were predominantly expressed in ovary tissues or young developing fruits, and 23 were transcriptionaly induced following fertilization. Thus, the self-probe subtraction did not select for genes weakly expressed in the target tissue while being highly expressed elsewhere in the plant. Of the receptor-like kinases (RLK) genes isolated, the leucine-rich repeat (LRR) family of RLK was by far the most represented with 25 members covering 11 LRR classes.

Characterization of a WRKY transcription factor expressed in late torpedo-stage embryos of Solanum chacoense.

A novel WRKY-like transcription factor was isolated from a screen for weakly expressed mRNAs in ovules in the self-incompatible wild potato species Solanum chacoense Bitt. This protein, named ScWRKY1, consisted of 525 amino acids and can be classified as a WRKY group-I member, having two WRKY domains. It is expressed at low levels in stems, roots, and petals, and expressed at much higher levels in leaves. Interestingly, although barely detectable in developing seeds, it is strongly and transiently expressed in fertilized ovules bearing late torpedo-staged embryos, suggesting a specific role during embryogenesis.

Fertilization induces strong accumulation of a histone deacetylase (HD2) and of other chromatin-remodeling proteins in restricted areas of the ovules.

Fertilization triggers a unique and complex developmental program leading to embryogenesis and seed set. Recently, mutations affecting chromatin-remodeling enzymes in plants have shown their key roles in development as demonstrated before in animal cells. Using a negative selection screen to isolate genes expressed in ovary tissues upon fertilization, we have identified a histone deacetylase gene (named ScHD2a ) of the plant-specific HD2 family, which is predominantly expressed in ovaries of the self-incompatible species Solanum chacoense. The ScHD2a is the probable orthologue of the Arabidopsis thaliana AtHD2a gene, which upon antisense suppression leads to aborted seeds formation. Transcription of the ScHD2a gene is strongly triggered by fertilization and transcripts accumulate predominantly in the micropylar region of the ovule's integument. Interestingly, this fertilization-induced accumulation pattern was also observed for other genes involved in transcriptional repression but not for a MYST-family histone acetyltransferase. The strong increase in ScHD2a mRNA levels in ovules after fertilization suggests an important and localized role for transcriptional repression in seed development, and indicates why silencing of the AtHD2a gene leads to aborted seed formation.