Diurnal Rhythms in the Red Seaweed Gracilariopsis chorda are Characterized by Unique Regulatory Networks of Carbon Metabolism.

Cellular and physiological cycles are driven by endogenous pacemakers, the diurnal and circadian rhythms. Key functions such as cell cycle progression and cellular metabolism are under rhythmic regulation, thereby maintaining physiological homeostasis. The photoreceptors phytochrome and cryptochrome, in response to light cues, are central input pathways for physiological cycles in most photosynthetic organisms. However, among Archaeplastida, red algae are the only taxa that lack phytochromes. Current knowledge about oscillatory rhythms is primarily derived from model species such as Arabidopsis thaliana and Chlamydomonas reinhardtii in the Viridiplantae, whereas little is known about these processes in other clades of the Archaeplastida, such as the red algae (Rhodophyta). We used genome-wide expression profiling of the red seaweed Gracilariopsis chorda and identified 3,098 rhythmic genes. Here, we characterized possible cryptochrome-based regulation and photosynthetic/cytosolic carbon metabolism in this species. We found a large family of cryptochrome genes in G. chorda that display rhythmic expression over the diurnal cycle and may compensate for the lack of phytochromes in this species. The input pathway gates regulatory networks of carbon metabolism which results in a compact and efficient energy metabolism during daylight hours. The system in G. chorda is distinct from energy metabolism in most plants, which activates in the dark. The green lineage, in particular, land plants, balance water loss and CO2 capture in terrestrial environments. In contrast, red seaweeds maintain a reduced set of photoreceptors and a compact cytosolic carbon metabolism to thrive in the harsh abiotic conditions typical of intertidal zones.

Caring for a loved one with Parkinson's disease: the role of coping styles and relationship quality.

OBJECTIVE: Informal carers play an essential role in the care of individuals with Parkinson's disease (PD). This role, however, is often fraught with difficulties, including emotional, physical, and financial. Coping styles and relationship quality have been hypothesized to influence the impact of stressors. The aim of this study is to examine the relationship between carers' coping style, relationship quality, and carer burden. DESIGN: Cross-sectional. PARTICIPANTS: Thirty-nine PD patient carer dyads were included in the study. MEASUREMENTS: Participants completed self-rated questionnaires including the Dyadic Adjustment Scale, Zarit Burden Interview, and Brief Coping Orientation to Problems Experienced Inventory. RESULTS: Correlational analyses found significant and positive correlation between carer burden and all three coping styles (problem-focused, emotion-focused, and dysfunctional). There was also a moderate association between carers' perceived relationship quality and satisfaction and carer burden. Regression analyses found that carer's gender, severity of PD, relationship quality, emotion-focused, and dysfunctional coping styles did not predict carer burden. Conversely, problem-focused coping style predicted carer burden. CONCLUSION: The results highlight that there is no perfect way to react and care for a loved one and serves as important information for practitioners who design and implement interventions.

The cross-section of routine practice of echocardiographic diastolic evaluation in atrial fibrillation in a community hospital: A quality improvement project.

BACKGROUND: The echocardiographic assessment of diastolic function in the context of atrial fibrillation (AF) has been controversial and can be challenging and labor-intensive. We aimed to assess the actual practice of diastolic evaluation in AF in our community hospital echocardiography laboratory and to improve clinical performance by a quality improvement project. METHODS: We reviewed 244 echocardiograms in patients with AF at the time of echocardiography from November 2019 to November 2020 (pre-intervention phase). We classified cases into a complete versus incomplete evaluation group according to the completeness of diastolic parameter measurement. After an educational intervention, we reviewed 68 echocardiograms in patients with AF from August 2021 to October 2021 (post-intervention phase). RESULTS: Our results demonstrated an improvement in a complete diastolic assessment from 69% to 91% after intervention (p < .001). In the pre-intervention phase, the four parameters (mitral inflow pulsed wave Doppler image, left atrium volume index, mitral annular tissue Doppler image [TDI], and tricuspid regurgitation Vmax), mitral annular TDI was not acquired in 71 out of 244 cases (29.1%) and those cases were classified as incomplete evaluation group. Interestingly, in the pre-intervention phase, 57 out of 162 cases (35%) with preserved EF (≥50%) received significantly more incomplete diastolic evaluation than 14 out of 82 patients (17%) with reduced EF (<50%) (p = .004). There were no statistically significant differences in age, BMI, the reason for requesting echocardiography, and patient level of care between the complete and incomplete evaluation groups. In the post-intervention phase, completeness of diastolic measurement in AF was significantly improved compared to the pre-intervention phase (29% vs. 9%, p < .001, respectively). CONCLUSION: A quality improvement project effectively improved the clinical performance of diastolic evaluation in AF in our community echocardiography laboratory. After the intervention, we decreased an incomplete evaluation from 30% to 9%. More efforts should be needed to increase awareness and familiarity in evaluating diastolic function in AF.

Multimodal Data Collection System for Driver Emotion Recognition Based on Self-Reporting in Real-World Driving.

As vehicles provide various services to drivers, research on driver emotion recognition has been expanding. However, current driver emotion datasets are limited by inconsistencies in collected data and inferred emotional state annotations by others. To overcome this limitation, we propose a data collection system that collects multimodal datasets during real-world driving. The proposed system includes a self-reportable HMI application into which a driver directly inputs their current emotion state. Data collection was completed without any accidents for over 122 h of real-world driving using the system, which also considers the minimization of behavioral and cognitive disturbances. To demonstrate the validity of our collected dataset, we also provide case studies for statistical analysis, driver face detection, and personalized driver emotion recognition. The proposed data collection system enables the construction of reliable large-scale datasets on real-world driving and facilitates research on driver emotion recognition. The proposed system is avaliable on GitHub.

Hippocampal correlates of episodic memory in Parkinson's disease: A systematic review of magnetic resonance imaging studies.

The present review asks whether magnetic resonance imaging (MRI) studies are able to define neural correlates of episodic memory within the hippocampus in Parkinson's disease (PD). Systematic searches were performed in PubMed, Web of Science, Medline, CINAHL, and EMBASE using search terms related to structural and functional MRI (fMRI), the hippocampus, episodic memory, and PD. Risk of bias was assessed for each study using the Newtown-Ottawa Scale. Thirty-nine studies met inclusion criteria; eight fMRI, seven diffusion MRI (dMRI), and 24 structural MRI (14 exploring whole hippocampus and 10 exploring hippocampal subfields). Critical analysis of the literature revealed mixed evidence from functional and dMRI, but stronger evidence from sMRI of the hippocampus as a biomarker for episodic memory impairment in PD. Hippocampal subfield studies most often implicated CA1, CA3/4, and subiculum volume in episodic memory and cognitive decline in PD. Despite differences in imaging methodology, study design, and sample characteristics, MRI studies have helped elucidate an important neural correlate of episodic memory impairment in PD with both clinical and theoretical implications. Natural progression of this work encourages future research on hippocampal subfield function as a potential biomarker of, or therapeutic target for, episodic memory dysfunction in PD.

DRER: Deep Learning-Based Driver's Real Emotion Recognizer.

In intelligent vehicles, it is essential to monitor the driver's condition; however, recognizing the driver's emotional state is one of the most challenging and important tasks. Most previous studies focused on facial expression recognition to monitor the driver's emotional state. However, while driving, many factors are preventing the drivers from revealing the emotions on their faces. To address this problem, we propose a deep learning-based driver's real emotion recognizer (DRER), which is a deep learning-based algorithm to recognize the drivers' real emotions that cannot be completely identified based on their facial expressions. The proposed algorithm comprises of two models: (i) facial expression recognition model, which refers to the state-of-the-art convolutional neural network structure; and (ii) sensor fusion emotion recognition model, which fuses the recognized state of facial expressions with electrodermal activity, a bio-physiological signal representing electrical characteristics of the skin, in recognizing even the driver's real emotional state. Hence, we categorized the driver's emotion and conducted human-in-the-loop experiments to acquire the data. Experimental results show that the proposed fusing approach achieves 114% increase in accuracy compared to using only the facial expressions and 146% increase in accuracy compare to using only the electrodermal activity. In conclusion, our proposed method achieves 86.8% recognition accuracy in recognizing the driver's induced emotion while driving situation.

Leriche Syndrome Misdiagnosed as Complex Regional Pain Syndrome in a Patient with Neuropathic Pain Caused by a Chip Fracture: A Case Report.

INTRODUCTION: Leriche syndrome is an aortoiliac occlusive disease caused by atherosclerotic occlusion. We report a case of Leriche syndrome with a fracture that was suspected as complex regional pain syndrome (CRPS), as the post-traumatic pain gradually worsened in the form of excruciating neuropathic pain. CASE REPORT: A 52-year-old woman with a history of hypertension was referred to the Department of Pain Medicine from a local orthopedic clinic because of suspected CRPS for excruciating neuropathic pain for one month. She complained of gait dysfunction and severe pain in the right foot following an incident of trauma with the right first toe. The average pain intensity assessed using the visual analog scale (VAS) was 90 (0: no pain, 100: the worst pain imaginable), and the neuropathic pain was evident as a score of 6/10 on Douleur neuropathique 4. Allodynia, hyperalgesia, blue discoloration of the skin, asymmetric temperature change (1.38 °C), and edematous soft tissue changes were observed. Ultrasonography showed a chip fracture in the first distal phalanx of the right first toe. The diagnosis was most probably CRPS type I according to the Budapest research criteria for CRPS. However, multiple pain management techniques were insufficient in controlling the symptoms. A month and a half later, an ankle-brachial index score of less than 0.4 suggested severe peripheral artery disease. Computed tomography angiography showed total occlusion between the infrarenal abdominal aorta and the bilateral common iliac arteries. Therefore, she underwent aortic-bifemoral bypass surgery with a diagnosis of Leriche syndrome. Three months after the surgery, the average pain intensity was graded as 10 on the VAS (0-100), the color of the skin of the right first toe improved and no gait dysfunction was observed. CONCLUSION: A chip fracture in a region with insufficient blood flow could manifest as excruciating neuropathic pain in Leriche syndrome.

Analysis of the Draft Genome of the Red Seaweed Gracilariopsis chorda Provides Insights into Genome Size Evolution in Rhodophyta.

Red algae (Rhodophyta) underwent two phases of large-scale genome reduction during their early evolution. The red seaweeds did not attain genome sizes or gene inventories typical of other multicellular eukaryotes. We generated a high-quality 92.1 Mb draft genome assembly from the red seaweed Gracilariopsis chorda, including methylation and small (s)RNA data. We analyzed these and other Archaeplastida genomes to address three questions: 1) What is the role of repeats and transposable elements (TEs) in explaining Rhodophyta genome size variation, 2) what is the history of genome duplication and gene family expansion/reduction in these taxa, and 3) is there evidence for TE suppression in red algae? We find that the number of predicted genes in red algae is relatively small (4,803-13,125 genes), particularly when compared with land plants, with no evidence of polyploidization. Genome size variation is primarily explained by TE expansion with the red seaweeds having the largest genomes. Long terminal repeat elements and DNA repeats are the major contributors to genome size growth. About 8.3% of the G. chorda genome undergoes cytosine methylation among gene bodies, promoters, and TEs, and 71.5% of TEs contain methylated-DNA with 57% of these regions associated with sRNAs. These latter results suggest a role for TE-associated sRNAs in RNA-dependent DNA methylation to facilitate silencing. We postulate that the evolution of genome size in red algae is the result of the combined action of TE spread and the concomitant emergence of its epigenetic suppression, together with other important factors such as changes in population size.

Discordancy and changes in the pattern of programmed death ligand 1 expression before and after platinum-based chemotherapy in metastatic gastric cancer.

BACKGROUND: Our goal was to evaluate changes in PD-L1 expression in primary tumours of metastatic gastric cancer before and after chemotherapy. METHODS: We evaluated the PD-L1 expression of 72 patients with primary gastric cancer, before and after palliative first-line platinum-based chemotherapy, between January 2015 and March 2017. The PD-L1 ratio was defined as pre-chemotherapy PD-L1 expression divided by the post-chemotherapy PD-L1 expression. RESULTS: In 30 patients with PD-L1 negative pre-chemotherapy, 12 (40%) were positive post-chemotherapy; among the 42 patients with PD-L1 positive pre-chemotherapy, 24 (57.1%) were negative post-chemotherapy. The degree of PD-L1 expression decreased from 58.3% before chemotherapy to 41.7% after chemotherapy (P = 0.046). Among patients with complete response/partial response (CR/PR), the degree of PD-L1 expression decreased (P = 0.002), as well as PD-L1 positivity with statistical significance (P = 0.013) after chemotherapy, but not among patients with stable disease/progressive disease (SD/PD). Higher disease control rates (CR/PR/SD) were observed in patients with an elevated PD-L1 ratio (P = 0.043). Patients with a high PD-L1 ratio (> 1) were found to be associated with a better progression-free survival (HR 0.34, 95% CI 0.17-0.67, P = 0.002). CONCLUSIONS: PD-L1 expression can change during chemotherapy. Moreover, changes in patterns of PD-L1 expression might be associated with patient prognosis and response to chemotherapy.

Dictyochophyceae Plastid Genomes Reveal Unusual Variability in Their Organization.

Dictyochophyceae (silicoflagellates) are unicellular freshwater and marine algae (Heterokontophyta, stramenopiles). Despite their abundance in global oceans and potential ecological significance, discovered in recent years, neither nuclear nor organellar genomes of representatives of this group were sequenced until now. Here, we present the first complete plastid genome sequences of Dictyochophyceae, obtained from four species: Dictyocha speculum, Rhizochromulina marina, Florenciella parvula and Pseudopedinella elastica. Despite their comparable size and genetic content, these four plastid genomes exhibit variability in their organization: plastid genomes of F. parvula and P. elastica possess conventional quadripartite structure with a pair of inverted repeats, R. marina instead possesses two direct repeats with the same orientation and D. speculum possesses no repeats at all. We also observed a number of unusual traits in the plastid genome of D. speculum, including expansion of the intergenic regions, presence of an intron in the otherwise non-intron-bearing psaA gene, and an additional copy of the large subunit of RuBisCO gene (rbcL), the last of which has never been observed in any plastid genome. We conclude that despite noticeable gene content similarities between the plastid genomes of Dictyochophyceae and their relatives (pelagophytes, diatoms), the number of distinctive features observed in this lineage strongly suggests that additional taxa require further investigation.

Flip-flop organization in the chloroplast genome of Capsosiphon fulvescens (Ulvophyceae, Chlorophyta).

To better understand organelle genome evolution of the ulvophycean green alga Capsosiphon fulvescens, we sequenced and characterized its complete chloroplast genome. The circular chloroplast genome was 111,561 bp in length with 31.3% GC content that contained 108 genes including 77 protein-coding genes, two copies of rRNA operons, and 27 tRNAs. In this analysis, we found the two types of isoform, called heteroplasmy, were likely caused by a flip-flop organization. The flip-flop mechanism may have caused structural variation and gene conversion in the chloroplast genome of C. fulvescens. In a phylogenetic analysis based on all available ulvophycean chloroplast genome data, including a new C. fulvescens genome, we found three major conflicting signals for C. fulvescens and its sister taxon Pseudoneochloris marina within 70 individual genes: (i) monophyly with Ulotrichales, (ii) monophyly with Ulvales, and (iii) monophyly with the clade of Ulotrichales and Ulvales. Although the 70-gene concatenated phylogeny supported monophyly with Ulvales for both species, these complex phylogenetic signals of individual genes need further investigations using a data-rich approach (i.e., organelle genome data) from broader taxon sampling.

Hemodynamic parameters and baroreflex sensitivity during head-up tilt test in patients with neurally mediated syncope.

BACKGROUND: We aimed to investigate differences in hemodynamic parameters and the role of baroreflex sensitivity (BRS) in patients with a history of neurally mediated syncope (NMS) compared with a control group. METHODS: Hemodynamic parameters and BRS were continuously measured noninvasively using a Finometer at rest and during passive head-up tilt test (HUT) in patients with a history of NMS (n = 55) and a control group (n = 77). The tilting period was divided into pretest (resting supine position), initial (first 3 minutes of tilting), last (last 3 minutes of tilting), and recovery (3 minutes after tilting was complete) periods. RESULTS: Decrease in systolic blood pressure (- 14.7 ± 15.7 mm Hg vs - 7.6 ± 14.3 mm Hg, P < 0.01) was more prominent and increase in total systemic peripheral resistance was significantly smaller (67.6 ± 418.7 dyn.s/cm5 vs 189.4 ± 261.0 dyn.s/cm5 , P = 0.04) from the initial to the last period of HUT in the patient group compared with the control group. BRS was significantly higher during the pretest period (20.1 ± 10.9 ms/mm Hg vs 13.0 ± 8.1 ms/mm Hg, P < 0.01) in the patient group, while the decrease in BRS from the pretest to the initial period was greater (-8.5 ± 6.0 ms/mm Hg vs - 3.2 ± 4.1 ms/mm Hg, P = 0.01). CONCLUSIONS: Dysfunctional BRS in response to orthostatic stress might be involved in pathological autonomic cardiac modulation of NMS.

Helicopter pilot scan techniques during low-altitude high-speed flight.

INTRODUCTION: This study examined pilots' visual scan patterns during a simulated high-speed, low-level flight and how their scan rates related to flight performance. As helicopters become faster and more agile, pilots are expected to navigate at low altitudes while traveling at high speeds. A pilot's ability to interpret information from a combination of visual sources determines not only mission success, but also aircraft and crew survival. METHODS: In a fixed-base helicopter simulator modeled after the U.S. Navy's MH-60S, 17 active-duty Navy helicopter pilots with varying total flight times flew and navigated through a simulated southern Californian desert course. Pilots' scan rate and fixation locations were monitored using an eye-tracking system while they flew through the course. Flight parameters, including altitude, were recorded using the simulator's recording system. RESULTS: Experienced pilots with more than 1000 total flight hours better maintained a constant altitude (mean altitude deviation = 48.52 ft, SD = 31.78) than less experienced pilots (mean altitude deviation = 73.03 ft, SD = 10.61) and differed in some aspects of their visual scans. They spent more time looking at the instrument display and less time looking out the window (OTW) than less experienced pilots. Looking OTW was associated with less consistency in maintaining altitude. DISCUSSION: Results may aid training effectiveness specific to helicopter aviation, particularly in high-speed low-level flight conditions.

Soluble c-Met protein as a susceptible biomarker for gastric cancer risk: A nested case-control study within the Korean Multicenter Cancer Cohort.

This study was conducted to evaluate the relevance of the soluble form of c-Met protein, a truncated form of the c-Met membrane receptor involved in the CagA pathway, as a potential biomarker for gastric cancer. Among 290 gastric cancer case-control sets selected from the Korean Multicenter Cancer Cohort, the plasma concentrations of soluble c-Met protein were measured with enzyme-linked immunosorbent assays. Using analysis of variance and covariance models with age, sex, smoking, Helicobacter pylori infection, and CagA seropositivity, the mean concentrations of soluble c-Met protein between cases and controls were compared. To evaluate the association between gastric cancer and a c-Met protein level, odds ratios and 95% confidence intervals were estimated using conditional logistic regression models. Interactions between CagA-related genes and the soluble c-Met protein concentration were also investigated. The overall median plasma concentration of soluble c-Met among cases was significantly lower than those of controls (1.390 vs. 1.610 ng/mL, p < 0.0001). Closer to the onset of gastric cancer, the soluble c-Met protein level decreased linearly in a time-dependent manner (p for trend = 0.0002). The combined effects between the CagA-related genes and the soluble c-Met protein concentration significantly intensified risks for gastric cancer. Restricted analyses including cases that had been diagnosed within 1 year after entering the cohort had a fair degree of ability (area under the receiver operating characteristic curve of 0.73-0.77) to discriminate gastric cancer cases from normal controls. Our findings demonstrate the potential of the soluble form of c-Met protein as a novel biomarker for gastric cancer. The beneficial effects of a high soluble c-Met concentration in human plasma are strongly supported.

Pilot performance: assessing how scan patterns & navigational assessments vary by flight expertise.

INTRODUCTION: Helicopter overland navigation is a cognitively complex task that requires continuous monitoring of system and environmental parameters and many hours of training to master. This study investigated the effect of expertise on pilots' gaze measurements, navigation accuracy, and subjective assessment of their navigation accuracy in overland navigation on easy and difficult routes. METHODS: A simulated overland task was completed by 12 military officers who ranged in flight experience as measured by total flight hours (TFH). They first studied a map of a route that included both easy and difficult route sections, and then had to 'fly' this simulated route in a fixed-base helicopter simulator. They also completed pre-task estimations and post-task assessments of the navigational difficulty of the transit to each waypoint in the route. Their scan pattern was tracked via eye tracking systems, which captured both the subject's out-the-window (OTW) and topographical map scan data. RESULTS: TFH was not associated with navigation accuracy or root mean square (RMS) error for any route section. For the easy routes, experts spent less time scanning out the window (p = 0.61) and had shorter OTW dwell (p = -0.66). For the difficult routes, experts appeared to slow down their scan by spending as much time scanning out the window as the novices while also having fewer Map fixations (p = -0.65) and shorter OTW dwell (p = -0.69). However, TFH was not significantly correlated with more accurate estimates of route difficulty. DISCUSSION: This study found that TFH did not predict navigation accuracy or subjective assessment, but was correlated with some gaze parameters.

Pilot perception and confidence of location during a simulated helicopter navigation task.

INTRODUCTION: This paper aims to provide insights into human perception, navigation performance, and confidence in helicopter overland navigation. Helicopter overland navigation is a challenging mission area because it is a complex cognitive task, and failing to recognize when the aircraft is off-course can lead to operational failures and mishaps. METHODS: A human-in-the-loop experiment to investigate pilot perception during simulated overland navigation by analyzing actual navigation trajectory, pilots' perceived location, and corresponding confidence levels was designed. There were 15 military officers with prior overland navigation experience who completed 4 simulated low-level navigation routes, 2 of which entailed auto-navigation. This route was paused roughly every 30 s for the subject to mark their perceived location on the map and their confidence level using a customized program. RESULTS: Analysis shows that there is no correlation between perceived and actual location of the aircraft, nor between confidence level and actual location. There is, however, some evidence that there is a correlation (rho = -0.60 to approximately 0.65) between perceived location and intended route of flight, suggesting that there is a bias toward believing one is on the intended flight route. DISCUSSION: If aviation personnel can proactively identify the circumstances in which usual misperceptions occur in navigation, they may reduce mission failure and accident rate. Fleet squadrons and instructional commands can benefit from this study to improve operations that require low-level flight while also improving crew resource management.

Public perceptions and attitudes of the national project of bio-big data: A nationwide survey in the Republic of Korea.

Background: The National Project of Bio-Big Data (NPBBD) is a South Korean bio-big data collection project, expected to include health, genomic, and lifelog data of one million Koreans. The Ethical, Legal, and Social Implications study is a parallel study active since 2020. As part of the study, a public survey was conducted to evaluate public attitudes towards engagement schemes, such as public committees and web portals for communication between the public and researchers. Methods: An online survey was conducted from March 3-9, 2021, using structured questionnaires addressed to 1,000 adults aged 20-59 years. Results: Several respondents reported a positive attitude towards participation (43.6% "somewhat," 14.3% "definitely"), whereas approximately one-third (36.5%) reported a neutral attitude. Positive factors that may affect the willingness of the respondents to participate included receiving health information (25.1%), contributing to research on cancer and rare diseases (21.9%), and advancing personalized medicine (21.5%). Conversely, negative factors were mainly associated with concerns regarding the risk of data leakage (22.8%), discrimination (21.1%), lack of information (13.5%), possibility of knowing the risk of being diagnosed with an incurable diseases (12.5%), and possibility of using data in industry (11.3%). In terms of project governance, respondents tended to recognize the importance of public participation in incorporating public opinion into the project design. Conclusion: These results have implications for the participant recruitment process, public engagement strategies, and the scope of user (academics/industry, domestic/overseas) accessibility to the database.

Origin of minicircular mitochondrial genomes in red algae.

Eukaryotic organelle genomes are generally of conserved size and gene content within phylogenetic groups. However, significant variation in genome structure may occur. Here, we report that the Stylonematophyceae red algae contain multipartite circular mitochondrial genomes (i.e., minicircles) which encode one or two genes bounded by a specific cassette and a conserved constant region. These minicircles are visualized using fluorescence microscope and scanning electron microscope, proving the circularity. Mitochondrial gene sets are reduced in these highly divergent mitogenomes. Newly generated chromosome-level nuclear genome assembly of Rhodosorus marinus reveals that most mitochondrial ribosomal subunit genes are transferred to the nuclear genome. Hetero-concatemers that resulted from recombination between minicircles and unique gene inventory that is responsible for mitochondrial genome stability may explain how the transition from typical mitochondrial genome to minicircles occurs. Our results offer inspiration on minicircular organelle genome formation and highlight an extreme case of mitochondrial gene inventory reduction.

Auxin regulation of the microRNA390-dependent transacting small interfering RNA pathway in Arabidopsis lateral root development.

MicroRNA (miR)390 cleaves the non-coding TAS3 precursor RNA for the production of tasiRNA-ARF, a group of an endogenous trans-acting small-interfering RNAs which cleave the transcripts of auxin response factor (ARF) 3/4. miR390-cleaved TAS3 RNA is polymerized and diced into tasiRNA-ARF by RNA-dependent RNA polymerase6 (RDR6) and Dicer-like4 (DCL4), respectively. tasiRNA-ARF-dependent post-transcriptional gene silencing (PTGS) of ARF3/4 is involved in auxin-mediated polarity establishment in the development of aerial lateral organs, such as leaf and flower. To understand how auxin regulates ARF4 expression, we examined auxin responsiveness of miR390 expression, which comprises a regulatory step for the biogenesis pathway of tasiRNA-ARF (the tasiRNA-ARF pathway), in Arabidopsis thaliana lateral root (LR) development. The results of this study provide evidence that miR390 expression is sensitive to TIR1-dependent transcriptional regulation and auxin concentration, and also that mutual negative-regulation between the tasiRNA-ARF pathway and ARF4 modulates the spatiotemporal expression of ARF4. We propose that, together with auxin concentration sensing through miR390 transcription, the tasiRNA-ARF pathway mediates the auxin response and ARF4-mediated LR developmental processes.