PIF7 is a master regulator of thermomorphogenesis in shade

Plant hypocotyl elongation response to light and temperature. Here the authors show that shade combined with warm temperature synergistically enhances the hypocotyl growth response via the PIF7 transcription factor, auxin, and as yet unknown factor.The size of plant organs is highly responsive to environmental conditions. The plant's embryonic stem, or hypocotyl, displays phenotypic plasticity, in response to light and temperature. The hypocotyl of shade avoiding species elongates to outcompete neighboring plants and secure access to sunlight. Similar elongation occurs in high temperature. However, it is poorly understood how environmental light and temperature cues interact to effect plant growth. We found that shade combined with warm temperature produces a synergistic hypocotyl growth response that dependent on PHYTOCHROME-INTERACTING FACTOR 7 (PIF7) and auxin. This unique but agriculturally relevant scenario was almost totally independent on PIF4 activity. We show that warm temperature is sufficient to promote PIF7 DNA binding but not transcriptional activation and we demonstrate that additional, unknown factor/s must be working downstream of the phyB-PIF-auxin module. Our findings will improve the predictions of how plants will respond to increased ambient temperatures when grown at high density

Neonatal Subventricular Zone Neural Stem Cells Release Extracellular Vesicles that Act as a Microglial Morphogen

Subventricular zone (SVZ) neural stem cells (NSCs) are the cornerstone of the perinatal neurogenic niche. Microglia are immune cells of the nervous system that are enriched in the neonatal SVZ. Although microglia regulate NSCs, the extent to which this interaction is bi-directional is unclear. Extracellular vesicles (EVs) are cell-derived particles that encase miRNA and proteins. Here, we demonstrate that SVZ NSCs generate and release EVs. Neonatal electroporated fluorescent EV fusion proteins were released by NSCs and subsequently cleared from the SVZ. EVs were preferentially targeted to microglia. Small RNA sequencing identified miRNAs within the EVs that regulate microglia physiology and morphology. EVs induced a transition to a CD11b/Iba1 non-stellate microglial morphology. The transition accompanied a microglial transcriptional state characterized by Let-7-regulated cytokine release and a negative feedback loop that controlled NSC proliferation. These findings implicate an NSC-EV-microglia axis and provide insight to normal and pathophysiological brain development

Tracing neuronal circuits in transgenic animals by transneuronal control of transcription (TRACT)

Comprender los cálculos que tienen lugar en los circuitos cerebrales requiere identificar cómo las neuronas de esos circuitos están conectadas entre sí. Describimos una técnica llamada TRACT (control de transcripción neuronal) basada en la proteólisis intramembrana inducida por ligando para revelar conexiones monosinápticas que surgen de las neuronas de interés marcadas genéticamente. En esta estrategia, las neuronas que expresan un ligando artificial (neuronas "donadoras") se unen y activan un receptor artificial de ingeniería genética en sus parejas sinápticas (neuronas "receptoras"). Tras la unión del ligando-receptor en las sinapsis, el receptor se escinde en su dominio transmembrana y libera un fragmento de proteína que activa la transcripción en las parejas sinápticas. Al usar TRACT en Drosophila, hemos confirmado la conectividad entre las neuronas receptoras olfativas y sus objetivos postsinápticos, y hemos descubierto nuevas conexiones potenciales entre las neuronas en el circuito circadiano. Nuestros resultados demuestran que el método TRACT se puede utilizar para investigar la conectividad de los circuitos neuronales en el cerebro.Understanding the computations that take place in brain circuits requires identifying how neurons in those circuits are connected to one another. We describe a technique called TRACT (TRAnsneuronal Control of Transcription) based on ligand-induced intramembrane proteolysis to reveal monosynaptic connections arising from genetically labeled neurons of interest. In this strategy, neurons expressing an artificial ligand (‘donor’ neurons) bind to and activate a genetically-engineered artificial receptor on their synaptic partners (‘receiver’ neurons). Upon ligand-receptor binding at synapses the receptor is cleaved in its transmembrane domain and releases a protein fragment that activates transcription in the synaptic partners. Using TRACT in Drosophila we have confirmed the connectivity between olfactory receptor neurons and their postsynaptic targets, and have discovered potential new connections between neurons in the circadian circuit. Our results demonstrate that the TRACT method can be used to investigate the connectivity of neuronal circuits in the brain.• National Institute of Health (USA). Beca UO 1109147, para Carlos LoispeerReviewe

Abscisic acid induced a negative geotropic response in dark-incubated Chlamydomonas reinhardtii

© 2019, The Author(s). The phytohormone abscisic acid (ABA) plays a role in stresses that alter plant water status and may also regulate root gravitropism and hydrotropism. ABA also exists in the aquatic algal progenitors of land plants, but other than its involvement in stress responses, its physiological role in these microorganisms remains elusive. We show that exogenous ABA significantly altered the HCO3− uptake of Chamydomonas reinhardtii in a light-intensity-dependent manner. In high light ABA enhanced HCO3− uptake, while under low light uptake was diminished. In the dark, ABA induced a negative geotropic movement of the algae to an extent dependent on the time of sampling during the light/dark cycle. The algae also showed a differential, light-dependent directional taxis response to a fixed ABA source, moving horizontally towards the source in the light and away in the dark. We conclude that light and ABA signal competitively in order for algae to position themselves in the water column to minimise photo-oxidative stress and optimise photosynthetic efficiency. We suggest that the development of this response mechanism in motile algae may have been an important step in the evolution of terrestrial plants and that its retention therein strongly implicates ABA in the regulation of their relevant tropisms

Chimeric Activators and Repressors Define HY5 Activity and Reveal a Light-Regulated Feedback Mechanism

The first exposure to light marks a crucial transition in plant development. This transition relies on the transcription factor HY5 controlling a complex downstream growth program. Despite its importance, its function in transcription remains unclear. Previous studies have generated lists of thousands of potential target genes and competing models of HY5 transcription regulation. In this work, we carry out detailed phenotypic and molecular analysis of constitutive activator and repressor HY5 fusion proteins. Using this strategy, we were able to filter out large numbers of genes that are unlikely to be direct targets, allowing us to eliminate several proposed models of HY5's mechanism of action. We demonstrate that the primary activity of HY5 is promoting transcription, and that this function relies on other, likely light-regulated, factors. In addition, this approach reveals a molecular feedback loop via the COP1/SPA E3-ubiquitin ligase complex suggesting novel mechanism which maintains low HY5 in the dark, primed for rapid accumulation to reprogram growth upon light exposure. Our strategy is broadly adaptable to the study of transcription factor activity. Lastly, we show that modulating this feedback loop can generate significant phenotypic diversity in both Arabidopsis and tomato

Dual PDF signaling pathways reset clocks via TIMELESS and acutely excite target neurons to control circadian behavior.

Molecular circadian clocks are interconnected via neural networks. In Drosophila, PIGMENT-DISPERSING FACTOR (PDF) acts as a master network regulator with dual functions in synchronizing molecular oscillations between disparate PDF(+) and PDF(-) circadian pacemaker neurons and controlling pacemaker neuron output. Yet the mechanisms by which PDF functions are not clear. We demonstrate that genetic inhibition of protein kinase A (PKA) in PDF(-) clock neurons can phenocopy PDF mutants while activated PKA can partially rescue PDF receptor mutants. PKA subunit transcripts are also under clock control in non-PDF DN1p neurons. To address the core clock target of PDF, we rescued per in PDF neurons of arrhythmic per⁰¹ mutants. PDF neuron rescue induced high amplitude rhythms in the clock component TIMELESS (TIM) in per-less DN1p neurons. Complete loss of PDF or PKA inhibition also results in reduced TIM levels in non-PDF neurons of per⁰¹ flies. To address how PDF impacts pacemaker neuron output, we focally applied PDF to DN1p neurons and found that it acutely depolarizes and increases firing rates of DN1p neurons. Surprisingly, these effects are reduced in the presence of an adenylate cyclase inhibitor, yet persist in the presence of PKA inhibition. We have provided evidence for a signaling mechanism (PKA) and a molecular target (TIM) by which PDF resets and synchronizes clocks and demonstrates an acute direct excitatory effect of PDF on target neurons to control neuronal output. The identification of TIM as a target of PDF signaling suggests it is a multimodal integrator of cell autonomous clock, environmental light, and neural network signaling. Moreover, these data reveal a bifurcation of PKA-dependent clock effects and PKA-independent output effects. Taken together, our results provide a molecular and cellular basis for the dual functions of PDF in clock resetting and pacemaker output

Evaluating Cancer Patients’ Expectations and Barriers Toward Traditional Chinese Medicine Utilization in China: A Patient-Support Group–Based Cross-Sectional Survey

Background: Traditional Chinese medicine (TCM) is widely used among Chinese cancer patients. However, little is known about Chinese patients’ expectations and barriers toward using TCM for cancer. Methods: We conducted a cross-sectional survey within a patient-support group, the Beijing Anti-Cancer Association. We measured the outcome, Chinese cancer survivors’ expectations and barriers toward TCM utilization, using a modified version of ABCAM (Attitudes and Beliefs towards Complementary and Alternative Medicine), the ABTCM (Attitudes and Beliefs towards Traditional Chinese Medicine). We used multivariate models to evaluate the impact of socioeconomic status and clinical factors on their expectations and barriers (including treatment concerns and logistical challenges domain) toward TCM. Results: Among 590 participants, most patients expected TCM to boost their immune system (96%), improve their physical health (96%), and reduce symptoms (94%). Many had logistical challenges (difficulty decocting herbs (58%) and finding a good TCM physician (55%)). A few were concerned that TCM might interfere with conventional treatments (7.6%), and that many TCM treatments are not based on scientific research (9.1%). In the multivariable regression model, age ≤60 years was independently associated with higher expectation score ( P = .031). Age ≤60 years (coefficient 5.0, P = .003) and localized disease (coefficient 9.5, P = .001) were both associated with higher treatment concerns. Active employment status (coefficient 9.0, P = .008) and localized disease (coefficient 7.5, P = .030) were related to more logistical challenges. Conclusion: Age and cancer stage were related to Chinese cancer patients’ perceived expectations and barriers toward TCM use. Understanding these attitudes is important for reshaping the role that TCM plays in China’s patient-centered comprehensive cancer care model

Model for a bifurcation in the PDFR signaling pathway controlling the molecular clock and neuronal excitability.

<p>PDFR acts through Gs and adenylate cyclase (AC) to increase levels of cAMP which may directly activate a cyclic-nucleotide-gated (CNG) channel (green pathway) to acutely depolarize the cell and increase the action potential firing rate. cAMP also activates PKA, promoting TIM stability and progression of the molecular clock (blue pathway). Light activates CRY, which promotes TIM degradation. The molecular clock also controls PKA transcripts, thereby controlling signal transduction to the clock through a feedback mechanism.</p