Metabolic and Physiological Regulation of Aspartic Acid-Mediated Enhancement of Heat Stress Tolerance in Perennial Ryegrass.

Aspartate is the most critical amino acid in the aspartate metabolic pathway, which is associated with multiple metabolic pathways, such as protein synthesis, nucleotide metabolism, TCA cycle, glycolysis, and hormone biosynthesis. Aspartate also plays an important role in plant resistance to abiotic stress, such as cold stress, drought stress, salt stress or heavy metal stress. This study found that the chlorophyll content and antioxidant active enzyme content (SOD, CAT, POD and APX) of perennial ryegrass treated with 2 mM aspartate were significantly higher than those treated with water under heat stress. The electrolyte leakage rate, MDA content and peroxide levels (O2- and H2O2) of perennial ryegrass treated with aspartate were significantly lower than those of perennial ryegrass treated with water, indicating that exogenous aspartate increases the content of chlorophyll, maintain the integrity of cell membrane system, and enhances SOD-CAT antioxidant pathway to eliminate the oxidative damage caused by ROS in perennial ryegrass under heat stress. Furthermore, exogenous aspartate could enhance the TCA cycle, the metabolism of the amino acids related to the TCA cycle, and pyrimidine metabolism to enhance the heat tolerance of perennial ryegrass.

LpNOL-knockdown suppression of heat-induced leaf senescence in perennial ryegrass involving regulation of amino acid and organic acid metabolism.

The nonyellow COLORING 1-like gene (NOL) is known for its roles in accelerating leaf senescence, but the underlying metabolic mechanisms for heat-induced leaf senescence remain unclear. The objectives of this study were to identify metabolites and associated metabolic pathways regulated by knockdown of NOL in perennial ryegrass (Lolium perenne) and to determine the metabolic mechanisms of NOL controlling heat-induced leaf senescence. Wild-type (WT; cv. "Pinnacle") and two lines (Noli-1 and Noli-2) of perennial ryegrass with LpNOL knockdown were exposed to heat stress at 35/33°C (day/night) or nonstress control temperatures at 25/22°C (day/night) for 30 days in growth chambers. Leaf electrolyte leakage, chlorophyll (Chl) content, photochemical efficiency (Fv /Fm ), and net photosynthetic rate (Pn) were measured as physiological indicators of leaf senescence, while gas chromatography-mass spectrometry was performed to identify metabolites regulated by LpNOL. Knockdown of LpNOL suppressed heat-induced leaf senescence and produced a stay-green phenotype in perennial ryegrass, as manifested by increased Chl content, photochemical efficiency, net photosynthetic rate, and cell membrane stability in Noli-1 and Noli-2. Five metabolites (valine, malic acid, threonic acid, shikimic acid, chlorogenic acid) were uniquely upregulated in LpNOL plants exposed to heat stress, and six metabolites (aspartic acid, glutamic acid, 5-oxoproline, phenylalanine, proline, tartaric acid) exhibited more pronounced increases in their content in LpNOL plants than the WT. LpNOL could regulate heat-induced leaf senescence in perennial ryegrass through metabolic reprogramming in the pathways of respiration, secondary metabolism, antioxidant metabolism, and protein synthesis.

Using Storytelling to Teach Effective Followership.

This chapter examines the craft of storytelling for the purpose of developing followers and exploring leader-follower transitions, while offering storytelling methods, classroom activities, and critical components of crafting a story. Through stories about the American Civil Rights icon, Mrs. Rosa Parks, and an unfamiliar Civil Rights activist, Sister Madeline Dorsey, a humble leader turned effective follower, it is possible to more easily appreciate the reflexive transition of follower to leader and leader to follower.

Cortical auditory distance representation based on direct-to-reverberant energy ratio.

Auditory distance perception and its neuronal mechanisms are poorly understood, mainly because 1) it is difficult to separate distance processing from intensity processing, 2) multiple intensity-independent distance cues are often available, and 3) the cues are combined in a context-dependent way. A recent fMRI study identified human auditory cortical area representing intensity-independent distance for sources presented along the interaural axis (Kopco et al. PNAS, 109, 11019-11024). For these sources, two intensity-independent cues are available, interaural level difference (ILD) and direct-to-reverberant energy ratio (DRR). Thus, the observed activations may have been contributed by not only distance-related, but also direction-encoding neuron populations sensitive to ILD. Here, the paradigm from the previous study was used to examine DRR-based distance representation for sounds originating in front of the listener, where ILD is not available. In a virtual environment, we performed behavioral and fMRI experiments, combined with computational analyses to identify the neural representation of distance based on DRR. The stimuli varied in distance (15-100 â€‹cm) while their received intensity was varied randomly and independently of distance. Behavioral performance showed that intensity-independent distance discrimination is accurate for frontal stimuli, even though it is worse than for lateral stimuli. fMRI activations for sounds varying in frontal distance, as compared to varying only in intensity, increased bilaterally in the posterior banks of Heschl's gyri, the planum temporale, and posterior superior temporal gyrus regions. Taken together, these results suggest that posterior human auditory cortex areas contain neuron populations that are sensitive to distance independent of intensity and of binaural cues relevant for directional hearing.

Intracortical depth analyses of frequency-sensitive regions of human auditory cortex using 7TfMRI.

Despite recent advances in auditory neuroscience, the exact functional organization of human auditory cortex (AC) has been difficult to investigate. Here, using reversals of tonotopic gradients as the test case, we examined whether human ACs can be more precisely mapped by avoiding signals caused by large draining vessels near the pial surface, which bias blood-oxygen level dependent (BOLD) signals away from the actual sites of neuronal activity. Using ultra-high field (7T) fMRI and cortical depth analysis techniques previously applied in visual cortices, we sampled 1mm isotropic voxels from different depths of AC during narrow-band sound stimulation with biologically relevant temporal patterns. At the group level, analyses that considered voxels from all cortical depths, but excluded those intersecting the pial surface, showed (a) the greatest statistical sensitivity in contrasts between activations to high vs. low frequency sounds and (b) the highest inter-subject consistency of phase-encoded continuous tonotopy mapping. Analyses based solely on voxels intersecting the pial surface produced the least consistent group results, even when compared to analyses based solely on voxels intersecting the white-matter surface where both signal strength and within-subject statistical power are weakest. However, no evidence was found for reduced within-subject reliability in analyses considering the pial voxels only. Our group results could, thus, reflect improved inter-subject correspondence of high and low frequency gradients after the signals from voxels near the pial surface are excluded. Using tonotopy analyses as the test case, our results demonstrate that when the major physiological and anatomical biases imparted by the vasculature are controlled, functional mapping of human ACs becomes more consistent from subject to subject than previously thought.

Interacting parallel pathways associate sounds with visual identity in auditory cortices.

Spatial and non-spatial information of sound events is presumably processed in parallel auditory cortex (AC) "what" and "where" streams, which are modulated by inputs from the respective visual-cortex subsystems. How these parallel processes are integrated to perceptual objects that remain stable across time and the source agent's movements is unknown. We recorded magneto- and electroencephalography (MEG/EEG) data while subjects viewed animated video clips featuring two audiovisual objects, a black cat and a gray cat. Adaptor-probe events were either linked to the same object (the black cat meowed twice in a row in the same location) or included a visually conveyed identity change (the black and then the gray cat meowed with identical voices in the same location). In addition to effects in visual (including fusiform, middle temporal or MT areas) and frontoparietal association areas, the visually conveyed object-identity change was associated with a release from adaptation of early (50-150ms) activity in posterior ACs, spreading to left anterior ACs at 250-450ms in our combined MEG/EEG source estimates. Repetition of events belonging to the same object resulted in increased theta-band (4-8Hz) synchronization within the "what" and "where" pathways (e.g., between anterior AC and fusiform areas). In contrast, the visually conveyed identity changes resulted in distributed synchronization at higher frequencies (alpha and beta bands, 8-32Hz) across different auditory, visual, and association areas. The results suggest that sound events become initially linked to perceptual objects in posterior AC, followed by modulations of representations in anterior AC. Hierarchical what and where pathways seem to operate in parallel after repeating audiovisual associations, whereas the resetting of such associations engages a distributed network across auditory, visual, and multisensory areas.

Combined MEG and EEG show reliable patterns of electromagnetic brain activity during natural viewing.

Naturalistic stimuli such as movies are increasingly used to engage cognitive and emotional processes during fMRI of brain hemodynamic activity. However, movies have been little utilized during magnetoencephalography (MEG) and EEG that directly measure population-level neuronal activity at a millisecond resolution. Here, subjects watched a 17-min segment from the movie Crash (Lionsgate Films, 2004) twice during simultaneous MEG/EEG recordings. Physiological noise components, including ocular and cardiac artifacts, were removed using the DRIFTER algorithm. Dynamic estimates of cortical activity were calculated using MRI-informed minimum-norm estimation. To improve the signal-to-noise ratio (SNR), principal component analyses (PCA) were employed to extract the prevailing temporal characteristics within each anatomical parcel of the Freesurfer Desikan-Killiany cortical atlas. A variety of alternative inter-subject correlation (ISC) approaches were then utilized to investigate the reliability of inter-subject synchronization during natural viewing. In the first analysis, the ISCs of the time series of each anatomical region over the full time period across all subject pairs were calculated and averaged. In the second analysis, dynamic ISC (dISC) analysis, the correlation was calculated over a sliding window of 200 ms with 3.3 ms steps. Finally, in a between-run ISC analysis, the between-run correlation was calculated over the dynamic ISCs of the two different runs after the Fisher z-transformation. Overall, the most reliable activations occurred in occipital/inferior temporal visual and superior temporal auditory cortices as well as in the posterior cingulate, precuneus, pre- and post-central gyri, and right inferior and middle frontal gyri. Significant between-run ISCs were observed in superior temporal auditory cortices and inferior temporal visual cortices. Taken together, our results show that movies can be utilized as naturalistic stimuli in MEG/EEG similarly as in fMRI studies.

Auditory conflict resolution correlates with medial-lateral frontal theta/alpha phase synchrony.

When multiple persons speak simultaneously, it may be difficult for the listener to direct attention to correct sound objects among conflicting ones. This could occur, for example, in an emergency situation in which one hears conflicting instructions and the loudest, instead of the wisest, voice prevails. Here, we used cortically-constrained oscillatory MEG/EEG estimates to examine how different brain regions, including caudal anterior cingulate (cACC) and dorsolateral prefrontal cortices (DLPFC), work together to resolve these kinds of auditory conflicts. During an auditory flanker interference task, subjects were presented with sound patterns consisting of three different voices, from three different directions (45° left, straight ahead, 45° right), sounding out either the letters "A" or "O". They were asked to discriminate which sound was presented centrally and ignore the flanking distracters that were phonetically either congruent (50%) or incongruent (50%) with the target. Our cortical MEG/EEG oscillatory estimates demonstrated a direct relationship between performance and brain activity, showing that efficient conflict resolution, as measured with reduced conflict-induced RT lags, is predicted by theta/alpha phase coupling between cACC and right lateral frontal cortex regions intersecting the right frontal eye fields (FEF) and DLPFC, as well as by increased pre-stimulus gamma (60-110 Hz) power in the left inferior fontal cortex. Notably, cACC connectivity patterns that correlated with behavioral conflict-resolution measures were found during both the pre-stimulus and the pre-response periods. Our data provide evidence that, instead of being only transiently activated upon conflict detection, cACC is involved in sustained engagement of attentional resources required for effective sound object selection performance.

Functional connectivity of dorsal and ventral frontoparietal seed regions during auditory orienting.

Our ability to refocus auditory attention is vital for even the most routine day-to-day activities. Shifts in auditory attention can be initiated "voluntarily," or triggered "involuntarily" by unexpected novel sound events. Here we employed psychophysiological interaction (PPI) analyses of auditory functional MRI data, to compare functional connectivity patterns of distinct frontoparietal cortex regions during cued voluntary vs. novelty-driven involuntary auditory attention shifting. Overall, our frontoparietal seed regions exhibited significant PPI increases with auditory cortex (AC) areas during both cued and novelty-driven orienting. However, significant positive PPI patterns associated with voluntary auditory attention (cue>novel task regressor), but mostly absent in analyses emphasizing involuntary orienting (novel>cue task regressor), were observed with seeds within the frontal eye fields (FEF), superior parietal lobule (SPL), and right supramarginal gyri (SMG). In contrast, significant positive PPIs associated selectively with involuntary orienting were observed between ACs and seeds within the bilateral anterior interior frontal gyri (IFG), left posterior IFG, SMG, and posterior cingulate cortices (PCC). We also found indices of lateralization of different attention networks: PPI increases selective to voluntary attention occurred primarily within right-hemispheric regions, whereas those related to involuntary orienting were more frequent with left-hemisphere seeds. In conclusion, despite certain similarities in PPI patterns across conditions, the more dorsal aspects of right frontoparietal cortex demonstrated wider connectivity during cued/voluntary attention shifting, whereas certain left ventral frontoparietal seeds were more widely connected during novelty-triggered/involuntary orienting. Our findings provide partial support for distinct attention networks for voluntary and involuntary auditory attention.

Meet the Fribbles: novel stimuli for use within behavioural research.

Clinical researchers make use of experimental models for mental disorders. In many cases, these models use stimuli that are relevant to the disorder under scrutiny, which allows one to experimentally investigate the factors that contribute to the development of the disorder. For example, one might use spiders or spider-like stimuli in the study of specific phobia. More broadly, researchers often make use of real-world stimuli such as images of animals, geometrical shapes or emotional words. However, these stimuli are often limited in their experimental controllability and their applicability to the disorder in question. We present a novel set of animal-like stimuli, called Fribbles, for use within behavioural research. Fribbles have desirable properties for use in research because they are similar to real-world stimuli, but due to their novelty, participants will not have had previous experience with them. They also have known properties that can be experimentally manipulated. We present an investigation into similarity between Fribbles in order to illustrate their utility in research that relies on comparisons between similar stimuli. Fribbles offer both experimental control and generalisability to the real world, although some consideration must be made concerning the properties that influence similarity between Fribbles when selecting them along a dimension of similarity.

Evidence for distinct human auditory cortex regions for sound location versus identity processing.

Neurophysiological animal models suggest that anterior auditory cortex (AC) areas process sound identity information, whereas posterior ACs specialize in sound location processing. In humans, inconsistent neuroimaging results and insufficient causal evidence have challenged the existence of such parallel AC organization. Here we transiently inhibit bilateral anterior or posterior AC areas using MRI-guided paired-pulse transcranial magnetic stimulation (TMS) while subjects listen to Reference/Probe sound pairs and perform either sound location or identity discrimination tasks. The targeting of TMS pulses, delivered 55-145 ms after Probes, is confirmed with individual-level cortical electric-field estimates. Our data show that TMS to posterior AC regions delays reaction times (RT) significantly more during sound location than identity discrimination, whereas TMS to anterior AC regions delays RTs significantly more during sound identity than location discrimination. This double dissociation provides direct causal support for parallel processing of sound identity features in anterior AC and sound location in posterior AC.

Distinct cortical networks activated by auditory attention and working memory load.

Auditory attention and working memory (WM) allow for selection and maintenance of relevant sound information in our minds, respectively, thus underlying goal-directed functioning in everyday acoustic environments. It is still unclear whether these two closely coupled functions are based on a common neural circuit, or whether they involve genuinely distinct subfunctions with separate neuronal substrates. In a full factorial functional MRI (fMRI) design, we independently manipulated the levels of auditory-verbal WM load and attentional interference using modified Auditory Continuous Performance Tests. Although many frontoparietal regions were jointly activated by increases of WM load and interference, there was a double dissociation between prefrontal cortex (PFC) subareas associated selectively with either auditory attention or WM. Specifically, anterior dorsolateral PFC (DLPFC) and the right anterior insula were selectively activated by increasing WM load, whereas subregions of middle lateral PFC and inferior frontal cortex (IFC) were associated with interference only. Meanwhile, a superadditive interaction between interference and load was detected in left medial superior frontal cortex, suggesting that in this area, activations are not only overlapping, but reflect a common resource pool recruited by increased attentional and WM demands. Indices of WM-specific suppression of anterolateral non-primary auditory cortices (AC) and attention-specific suppression of primary AC were also found, possibly reflecting suppression/interruption of sound-object processing of irrelevant stimuli during continuous task performance. Our results suggest a double dissociation between auditory attention and working memory in subregions of anterior DLPFC vs. middle lateral PFC/IFC in humans, respectively, in the context of substantially overlapping circuits.

Assessment of ruminal degradation, oral bioavailability, and toxic effects of anticoagulant rodenticides in sheep.

OBJECTIVE: To assess the rate and extent of ruminal degradation of warfarin, chlorophacinone, and bromadiolone in vitro and determine the oral availability and clinical and hemostatic effects of each anticoagulant rodenticide in adult sheep. ANIMALS: 3 Texel sheep. PROCEDURE: Samples of ruminal fluid were incubated with each of the anticoagulants to assess the kinetics of ruminal degradation over 24 hours. To determine the plasma kinetics of the anticoagulants, each sheep received each of the anticoagulants IV or via a rumenimplanted cannula at 2-month intervals (3 rodenticide exposures/sheep). At intervals during a 240- to 360- hour period after treatment, prothrombin time (PT) was measured, plasma anticoagulant concentration was assessed, and clinical signs of rodenticide poisoning were monitored. In plasma and rumen extracts, anticoagulant concentrations were determined via high-performance liquid chromatography. RESULTS: In the rumen extracts, anticoagulants were slightly degraded (< 15%) over 24 hours. In vivo, oral availability of warfarin, chlorophacinone, and bromadiolone was estimated at 79%, 92%, and 88%, respectively. Although maximum PT was 80 seconds after chlorophacinone and bromadiolone treatments, no clinical signs of toxicosis were detected; PT returned to baseline values within 2 weeks. CONCLUSIONS AND CLINICAL RELEVANCE: In sheep, warfarin, chlorophacinone, and bromadiolone were not degraded in the rumen but their bioavailabilities were high after oral administration; the kinetics of these compounds in sheep and other mammals are quite similar. These data suggest that the lack of susceptibility of ruminants to these anticoagulant rodenticides cannot be explained by either ruminal degradation or the specific toxicokinetics of these anticoagulants.