Academic literature on the topic 'Signal activation pattern'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Signal activation pattern.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Signal activation pattern"
1
Lakatos, Stephen. "Recognition of Complex Auditory-Spatial Patterns." Perception 22, no. 3 (March 1993): 363–74. http://dx.doi.org/10.1068/p220363.
Full textAbstract:
Two experiments were carried out to investigate the perception of complex auditory-spatial patterns. Subjects were asked to identify alphanumeric characters whose patterns could be outlined acoustically through the sequential activation of specific units in a speaker array. Signal bandwidths were varied systematically in both experiments. Signals in experiment 1 had sharp onsets and offsets; envelope shapes in experiment 2 were much more gradual. Subjects showed considerable ability in recognizing alphanumeric patterns traced with signals of varying acoustical composition. Reductions in the steepness of signal attack and decay produced limited declines in pattern recognition ability. Systematic trends in the relation between patterns and the distribution of incorrect responses suggest that subjects performed a pattern-matching task, in which identifications were made on the basis of component features. The unexpected pattern recognition abilities that subjects demonstrated in both experiments suggest that spatial hearing, like vision, has access to mechanisms for amodal spatial representations.
2
Miller, D. T., and R. L. Cagan. "Local induction of patterning and programmed cell death in the developing Drosophila retina." Development 125, no. 12 (June 15, 1998): 2327–35. http://dx.doi.org/10.1242/dev.125.12.2327.
Full textAbstract:
Local cell signaling can pattern the nervous system by directing cell fates, including programmed cell death. In the developing Drosophila retina, programmed cell death is used to remove excess cells between ommatidia. Cell ablation revealed the source and position of signals required for regulating the pattern of programmed cell death among these interommatidial cells. Two types of signals regulate this patterning event. Notch-mediated signals between interommatidial precursors result in removal of unneeded cells. Cone cells and primary pigment cells oppose this signal by supplying a ‘life’-promoting activity; evidence is provided that this signal occurs through localized activation of the EGF Receptor/Ras pathway. Together, these signals refine the highly regular pattern observed in the adult retina.
3
Albarrán-Juárez, Julián, Andras Iring, ShengPeng Wang, Sayali Joseph, Myriam Grimm, Boris Strilic, Nina Wettschureck, Till F. Althoff, and Stefan Offermanns. "Piezo1 and Gq/G11 promote endothelial inflammation depending on flow pattern and integrin activation." Journal of Experimental Medicine 215, no. 10 (September 7, 2018): 2655–72. http://dx.doi.org/10.1084/jem.20180483.
Full textAbstract:
The vascular endothelium is constantly exposed to mechanical forces, including fluid shear stress exerted by the flowing blood. Endothelial cells can sense different flow patterns and convert the mechanical signal of laminar flow into atheroprotective signals, including eNOS activation, whereas disturbed flow in atheroprone areas induces inflammatory signaling, including NF-κB activation. How endothelial cells distinguish different flow patterns is poorly understood. Here we show that both laminar and disturbed flow activate the same initial pathway involving the mechanosensitive cation channel Piezo1, the purinergic P2Y2 receptor, and Gq/G11-mediated signaling. However, only disturbed flow leads to Piezo1- and Gq/G11-mediated integrin activation resulting in focal adhesion kinase-dependent NF-κB activation. Mice with induced endothelium-specific deficiency of Piezo1 or Gαq/Gα11 show reduced integrin activation, inflammatory signaling, and progression of atherosclerosis in atheroprone areas. Our data identify critical steps in endothelial mechanotransduction, which distinguish flow pattern-dependent activation of atheroprotective and atherogenic endothelial signaling and suggest novel therapeutic strategies to treat inflammatory vascular disorders such as atherosclerosis.
4
Hesketh, R., T. A. Moore, S. R. Pennington, G. A. Smith, and J. C. Metcalfe. "Analysis of the primary signals required for activation of the mitogenic pathway in murine thymocytes from protein phosphorylation patterns." Journal of Immunology 145, no. 8 (October 15, 1990): 2571–80. http://dx.doi.org/10.4049/jimmunol.145.8.2571.
Full textAbstract:
Abstract It has been proposed that phorbol esters and the Ca2+ ionophore A23187 are effective comitogens for some species of lymphocytes because together they mimic the normal secondary signals for cell activation by mitogens that cause phosphatidylinositol 4,5-bisphosphate (PtdInsP2) breakdown (e.g., anti-TCR and anti-Thy-1 antibodies and Con A). To test whether activation of protein kinase C and an increase in [Ca2+]i account for the activation of the mitogenic pathway in murine thymocytes by the mitogens that cause PtdInsP2 breakdown, the two-dimensional phosphorylation patterns generated by the three classes of mitogens (protein kinase C activator, Ca2+ ionophore, and activator of PtdInsP2 breakdown) and by activators of cAMP-dependent kinases have been compared. From the phosphorylation patterns, by which each mitogen could be distinguished reproducibly, it was concluded that: 1) The phosphorylation patterns generated by the mitogens that activate PtdInsP2 breakdown are only slightly affected by the removal of extracellular Ca2+ under conditions that abolish the normal rise in [Ca2+]i and do not therefore depend on the activation of Ca2(+)-dependent protein kinases. In contrast, the phosphorylation pattern generated by A23187 is totally dependent on extracellular Ca2+. 2) Neither A23187 nor the mitogens that activate PtdInsP2 breakdown nor activators of cAMP-dependent kinases caused significant activation of protein kinase C assayed by phosphorylation of the diagnostic proteins 80b and 78a. Consistent with this conclusion, only the phorbol esters or oleoyl acyl glycerol caused translocation of protein kinase C activity from the cytosolic to the membrane fraction. 3) Neither A23187 nor the mitogens that cause PtdInsP2 breakdown activated cAMP-dependent kinases. Taken together the data imply that the mitogens that cause PtdInsP2 breakdown must generate an additional, independent primary mitogenic signal. It is suggested that this signal may be the activation of tyrosine kinases (e.g., p56lck) via the TCR and working hypotheses for effective combinations of primary mitogenic signals that will activate DNA synthesis are developed.
5
Lin, Genghong, Feng Jiao, Qiwen Sun, Moxun Tang, Jianshe Yu, and Zhan Zhou. "Linking dynamical complexities from activation signals to transcription responses." Royal Society Open Science 6, no. 3 (March 2019): 190286. http://dx.doi.org/10.1098/rsos.190286.
Full textAbstract:
The transcription of inducible genes involves signalling pathways that induce DNA binding of the downstream transcription factors to form functional promoter states. How the transcription dynamics is linked to the temporal variations of activation signals is far from being fully understood. In this work, we develop a mathematical model with multiple promoter states to address this question. Each promoter state has its own activation and inactivation rates and is selected randomly with a probability that may change in time. Under the activation of constant signals, our analysis shows that if only the activation rates differ among the promoter states, then the mean transcription level m ( t ) displays only a monotone or monophasic growth pattern. In a sharp contrast, if the inactivation rates change with the promoter states, then m ( t ) may display multiphasic growth patterns. Upon the activation of signals that oscillate periodically, m ( t ) also oscillates later, almost periodically at the same frequency, but the magnitude decreases with frequency and is almost completely attenuated at high frequencies. This gives a surprising indication that multiple promoter states could filter out the signal oscillation and the noise in the random promoter state selection, as observed in the transcription of a gene activated by p53 in breast carcinoma cells. Our approach may help develop a theoretical framework to integrate coherently the genetic circuit with the promoter states to elucidate the linkage from the activation signal to the temporal profile of transcription outputs.
6
Kim, Jae Gyu, Sung Joong Lee, and Martin F. Kagnoff. "Nod1 Is an Essential Signal Transducer in Intestinal Epithelial Cells Infected with Bacteria That Avoid Recognition by Toll-Like Receptors." Infection and Immunity 72, no. 3 (March 2004): 1487–95. http://dx.doi.org/10.1128/iai.72.3.1487-1495.2004.
Full textAbstract:
ABSTRACT The transcription factor NF-κB in human intestinal epithelial cells plays a central role in regulating genes that govern the onset of mucosal inflammatory responses following intestinal microbial infection. Nod1 is a cytosolic pattern recognition receptor in mammalian cells that senses components of microbial peptidoglycans and signals the activation of NF-κB. The aim of these studies was to assess the functional importance of Nod1 in activating NF-κB and NF-κB proinflammatory target genes in human intestinal epithelium. Human colon epithelial cells that constitutively express Nod1 were used as a model intestinal epithelium. These cells do not signal through Toll-like receptor 4 (TLR4) or respond to bacterial lipopolysaccharide, but they express functional TLR5 and interleukin 1 (IL-1) receptors that signal the activation of NF-κB in response to bacterial flagellin or IL-1 stimulation. Stable expression of dominant negative (DN) Nod1 in colon epithelial cells prevented IκB kinase and NF-κB activation in response to infection with enteroinvasive Escherichia coli. In contrast, DN Nod1 did not eliminate IL-1 or flagellin-stimulated NF-κB activation. Inhibition of NF-κB was accompanied by inhibition of NF-κB target genes that provide signals for the mucosal influx of neutrophils during intestinal infection. We conclude that signaling through Nod1 is required for activating NF-κB in human intestinal epithelial cells infected with gram-negative enteric bacteria that can bypass TLR activation. Signaling through Nod1 provides the intestinal epithelium with a backup mechanism for rapidly activating innate immunity during infection with a group of highly invasive pathogenic gram-negative bacteria.
7
Xie, Chuyang, Xiguang Gao, Huajun Zhang, and Yingdong Song. "Multiscale acoustic emission of C/SiC mini-composites and damage identification using pattern recognition." Science and Engineering of Composite Materials 27, no. 1 (May 30, 2020): 148–62. http://dx.doi.org/10.1515/secm-2020-0015.
Full textAbstract:
AbstractIn this paper, multiscale acoustic emission (AE) signal analysis was applied to acoustic emission data processing to classify the AE signals produced during the tensile process of C/SiC mini-composites. An established unsupervised clustering algorithm was provided to classify an unknown set of AE data into reasonable classes. In order to correctly match the obtained classes of the AE signals with the damage mode of the sample, three scales of materials were involved. Single fiber tensile test and fiber bundle tensile test were firstly performed to achieve the characteristics of AE signal of fiber fracture. Parameter analysis and waveform analysis were added to extract the different features of each class of signals in the In-situ tensile test of C/SiC mini-composite. The change of strain field on the sample surface analyzed by DIC (Digital Image Correlation) revealed the corresponding relationship between matrix cracking and AE signals. Microscopic examinationwas used to correlate the clusters to the damage mode. By analyzing the evolution process of signal activation for each class against the load, it also provided a reliable basis for the correlation between the obtained classes of the AE signals and the damage mechanism of the material.
8
Haglund, Michael M., Joseph R. Meno, Daryl W. Hochman, Al C. Ngai, and H. Richard Winn. "Correlation of intrinsic optical signal, cerebral blood flow, and evoked potentials during activation of rat somatosensory cortex." Journal of Neurosurgery 109, no. 4 (October 2008): 654–63. http://dx.doi.org/10.3171/jns/2008/109/10/0654.
Full textAbstract:
Object This study was undertaken to test the hypothesis that cerebral blood flow (CBF) and the intrinsic optical signal could be dissociated by altering adenosine receptor activity and to uncover the origin of the optic signal using a cranial window in the anesthetized rat. Methods In anesthetized, ventilated, and temperature-controlled rats with closed cranial windows, the authors evaluated simultaneously the alterations in pial arteriolar diameter, intrinsic optical signals (690 nm), and somatosensory evoked potentials during cortical activation evoked by contralateral sciatic nerve stimulation (SNS). To dissociate the vascular and intrinsic signal, they topically applied the adenosine receptors antagonists theophylline (5 μM), which affects A1 and A2A receptors, and 8-cyclopentyl-1,3-dipropylxanthine (CPX, 1 μM), which blocks the A1 receptor. The former interacts primarily with the vasculature whereas the latter influences the parenchyma exclusively. Results During 20 seconds of contralateral SNS, pial arterioles in the hindlimb somatosensory cortex dilated in a characteristic peak and shoulder pattern. As compared with mock cerebrospinal fluid alone, theophylline significantly (p < 0.05) attenuated SNS-induced vasodilation (mean ± standard deviation 8.1 ± 2.5% vs 21.7 ± 1.9%; 4 rats in each group). In contrast, CPX potentiated vasodilation significantly (p < 0.05) during SNS (54.7 ± 15.8% for the CPX group vs 20.1 ± 1.9% for the controls; 5 rats in each group). The change in optical signal persisted after cessation of SNS in all the animals. Thus, the pattern of change of the optical signal was distinctly different from the pattern of changes in arteriolar diameter (which returned rapidly to baseline). Moreover, the optical signal during SNS was increased by 50% by theophylline and by almost 5-fold by CPX (p < 0.05). The area of change of the intrinsic signal was also increased by the topical application of theophylline and CPX. The somatosensory evoked potential recordings revealed no significant changes after theophylline application, but CPX caused a small diminution of the N1 wave (p < 0.01). Conclusions The noncongruent temporal profiles of the changes in pial arteriolar diameter and optical signal, imaged at 690 nm, indicate that the optical signal at 690 nm is not related to CBF. Alteration of adenosine receptor activity independently changed cortical activity, as measured by the optical signal, and CBF, as determined by pial arteriolar diameter. Manipulation of the adenosine receptor activity during increased cortical activity confirmed the temporal dissociation of optical signal and CBF and provided further evidence for the role of adenosine in regulating CBF.
9
Lima Alberton, Cristine, Stephanie Santana Pinto, Natália Amélia da Silva Azenha, Eduardo Lusa Cadore, Marcus Peikriszwili Tartaruga, Bruno Brasil, and Luiz Fernando Martins Kruel. "Kinesiological Analysis of Stationary Running Performed in Aquatic and Dry Land Environments." Journal of Human Kinetics 49, no. 1 (December 1, 2015): 5–14. http://dx.doi.org/10.1515/hukin-2015-0103.
Full textAbstract:
Abstract The purpose of the present study was to analyze the electromyographic (EMG) signals of the rectus femoris (RF), vastus lateralis (VL), semitendinosus (ST) and short head of the biceps femoris (BF) during the performance of stationary running at different intensities in aquatic and dry land environments. The sample consisted of 12 female volunteers who performed the stationary running exercise in aquatic and dry land environments at a submaximal cadence (80 beats·min-1 controlled by a metronome) and at maximal velocity, with EMG signal measurements from the RF, VL, ST and BF muscles. The results showed a distinct pattern between environments for each muscle examined. For the submaximal cadence of 80 beats·min-1, there was a reduced magnitude of the EMG signal in the aquatic environment, except for the ST muscle, the pattern of which was similar in both environments. In contrast to the submaximal cadence, the pattern of the EMG signal from all of the muscles showed similar magnitudes for both environments and phases of movement at maximal velocity, except for the VL muscle. Therefore, the EMG signals from the RF, VL, ST and BF muscles of women during stationary running had different patterns of activation over the range of motion between aquatic and dry land environments for different intensities. Moreover, the neuromuscular responses of the lower limbs were optimized by an increase in intensity from submaximal cadence to maximal velocity.
10
Berg, Nancy N., Lawrence G. Puente, Wojciech Dawicki, and Hanne L. Ostergaard. "Sustained TCR Signaling Is Required for Mitogen-Activated Protein Kinase Activation and Degranulation by Cytotoxic T Lymphocytes." Journal of Immunology 161, no. 6 (September 15, 1998): 2919–24. http://dx.doi.org/10.4049/jimmunol.161.6.2919.
Full textAbstract:
Abstract Requirements for T cell activation are not fully established. One model is that receptor occupancy and down-regulation are essential for activation, and another, not necessarily mutually exclusive, model is that sustained signals are important. Here we examine the importance of signal duration in T cell activation. First, we demonstrate that immobilized, but not soluble cross-linked, Abs to CD3 stimulate degranulation by CTL. The cross-linked Abs are not deficient in their ability to signal since they stimulate the same tyrosine phosphorylation pattern as immobilized Ab, but it is very transient relative to that stimulated by immobilized Ab. Furthermore, novel decreased migratory forms of Lck occur to a significant extent only after stimulation with immobilized Abs. A dramatic difference in the duration of signals is very evident when mitogen-activated protein kinase (MAPK) activity is examined. Immobilized anti-CD3 stimulates very high levels of MAPK activation that is still detectable 1 h after stimulation. In contrast, cross-linked Ab stimulates only transient and incomplete activation of MAPK. Taken together, these results suggest that TCR engagement and induction of tyrosine phosphorylation alone are not sufficient for T cell activation and that the duration of TCR-stimulated signals is critical to attain a functional response.
Dissertations / Theses on the topic "Signal activation pattern"
1
Lee, Jae-Min. "Characterization of spatial and temporal brain activation patterns in functional magnetic resonance imaging data." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013024.
Full text
2
Zanghieri, Marcello. "sEMG-based hand gesture recognition with deep learning." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18112/.
Full textAbstract:
Hand gesture recognition based on surface electromyographic (sEMG) signals is a promising approach for the development of Human-Machine Interfaces (HMIs) with a natural control, such as intuitive robot interfaces or poly-articulated prostheses. However, real-world applications are limited by reliability problems due to motion artifacts, postural and temporal variability, and sensor re-positioning.
This master thesis is the first application of deep learning on the Unibo-INAIL dataset, the first public sEMG dataset exploring the variability between subjects, sessions and arm postures, by collecting data over 8 sessions of each of 7 able-bodied subjects executing 6 hand gestures in 4 arm postures. In the most recent studies, the variability is addressed with training strategies based on training set composition, which improve inter-posture and inter-day generalization of classical (i.e. non-deep) machine learning classifiers, among which the RBF-kernel SVM yields the highest accuracy.
The deep architecture realized in this work is a 1d-CNN implemented in Pytorch, inspired by a 2d-CNN reported to perform well on other public benchmark databases. On this 1d-CNN, various training strategies based on training set composition were implemented and tested.
Multi-session training proves to yield higher inter-session validation accuracies than single-session training. Two-posture training proves to be the best postural training (proving the benefit of training on more than one posture), and yields 81.2% inter-posture test accuracy. Five-day training proves to be the best multi-day training, and yields 75.9% inter-day test accuracy. All results are close to the baseline. Moreover, the results of multi-day trainings highlight the phenomenon of user adaptation, indicating that training should also prioritize recent data.
Though not better than the baseline, the achieved classification accuracies rightfully place the 1d-CNN among the candidates for further research.
Books on the topic "Signal activation pattern"
1
Stamatakis, Emmanuel A., Eleni Orfanidou, and Andrew C. Papanicolaou. Functional Magnetic Resonance Imaging. Edited by Andrew C. Papanicolaou. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780199764228.013.7.
Full textAbstract:
Functional magnetic resonance imaging (fMRI) is the most frequently used functional neuroimaging method and the one that accounts for most of the neuroimaging literature. It measures the blood oxygen level-dependent (BOLD) signal in different parts of the brain during rest and during task-induced activation of functional networks mediating basic and higher functions. A basic understanding of the various instruments and techniques of recording the hemodynamic responses of different brain regions and the manner in which we establish activation and connectivity patterns out of these responses is necessary for an appreciation of the contemporary functional neuroimaging literature. To facilitate such an understanding is the purpose of this chapter.
Book chapters on the topic "Signal activation pattern"
1
Thabet, Mohamad, David Sanders, and Nils Bausch. "Detection of Patterns in Pressure Signal of Compressed Air System Using Wavelet Transform." In Springer Proceedings in Energy, 61–67. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63916-7_8.
Full textAbstract:
AbstractThis paper investigates detecting patterns in the pressure signal of a compressed air system (CAS) with a load/unload control using a wavelet transform. The pressure signal of a CAS carries useful information about operational events. These events form patterns that can be used as ‘signatures’ for event detection. Such patterns are not always apparent in the time domain and hence the signal was transformed to the time-frequency domain. Three different CAS operating modes were considered: idle, tool activation and faulty. The wavelet transforms of the CAS pressure signal reveal unique features to identify events within each mode. Future work will investigate creating machine learning tools for that utilize these features for fault detection in CAS.
2
Choong, Wen Yean, Wan Khairunizam, M. Murugappan, Wan Azani Mustafa, Abdul Hamid Adom, Siao Zheng Bong, Ahmad Kadri Junoh, Zuradzman Mohamad Razlan, and Shahriman Abu Bakar. "Investigation of the Brain Activation Pattern of Stroke Patients and Healthy Individuals During Happiness and Sadness." In Biomedical Signals Based Computer-Aided Diagnosis for Neurological Disorders, 103–29. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97845-7_6.
Full text
3
Hess, A., Y. Hosokawa, M. Nasu, J. Horikawa, I. Taniguchi, and H. Scheich. "De-correlating the Spatio-temporal Signals of Multi-field Cortical Activation Patterns Recorded by Voltage Sensitive Dye Imaging." In Bildverarbeitung für die Medizin 2002, 362–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-642-55983-9_85.
Full text
4
Belic, Aleš, and Vito Logar. "Identification of Motor Functions Based on an EEG Analysis." In Medical Applications of Intelligent Data Analysis, 172–86. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-1803-9.ch011.
Full textAbstract:
A combination of several techniques is necessary for a reliable identification of activities based on EEG signals. A separation of the overlapping patterns in the EEG signals is often performed first. These separated patterns are then analysed by some artificial intelligence methods in order to identify the activity. As pattern separation and activity identification are often linked, the two processes must be tuned to a specific problem, thus losing some generality of the procedure. The complexity of the patterns in EEG signals is often too great for completely automated pattern recognition. In this case, phase demodulation was introduced as a procedure for the extraction of the phase properties of the EEG signals. These phase shifts are known to correlate with the brain activity; therefore, phase-demodulated EEG signals were used to predict the motor activity. Three studies with off-line identification of the motor activities have been performed so far. In the first study, a continuous gripping force was predicted. In the second study, index- and middle-finger activation was predicted, and in the final study, wrist movements were analysed. The presented procedure can be used for designing a continuous brain-computer interface.
5
Jayaram Pratima, Bichandarkoil, and Namasivayam Nalini. "Efferocytosis: An Interface between Apoptosis and Pathophysiology." In Regulation and Dysfunction of Apoptosis. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.97819.
Full textAbstract:
Several cell death modes, each with a unique feature and mode of inducing cell death have been established. Cell death occurring under physiological conditions is primarily caused by apoptosis, which is a non-inflammatory or silent process, whereas necroptosis or pyroptosis is triggered by pathogen invasion, which stimulates the immune system and induces inflammation. In physiology, clearing dead cells and associated cellular debris is necessary since billions of cells die during mammalian embryogenesis and every day in adult organisms. For degradation, dead cells produced by apoptosis are quickly engulfed by macrophages. This chapter will present a description of the phagocytosis of dead and dying cells, by a process known as efferocytosis. Macrophages and, to a lesser degree, other ‘professional’ phagocytes (such as monocytes and dendritic cells) and ‘non-professional’ phagocytes, such as epithelial cells, conduct efferocytosis. Recent discoveries have shed light on this mechanism and how it works to preserve homeostasis of tissue, repair of tissue and health of the organism. Caspases are a large family of proteases of cysteine acting in cascades. A cascade leading to activation of caspase 3 mediates apoptosis and is responsible for killing cells, hiring macrophages, and presenting a “eat me” signal(s). If macrophages do not effectively engulf apoptotic cells, they undergo secondary necrosis and release intracellular materials that reflect a molecular pattern associated with injury, which can lead to autoimmune diseases. Here, the processes of efferocytosis are illustrated and the pathophysiological effects that which occur when this phase is abrogated are highlighted.
6
Dik, Olga E., and Alexander D. Nozdrachev. "Chapter 7. Mechanisms of antinoceptive response of a sensory neuron." In Mechanisms of changes in dynamical complexity of physiological signal patterns, 132–75. St. Petersburg State University, 2019. http://dx.doi.org/10.21638/11701/9785288059322.08.
Full textAbstract:
The seventh chapter is devoted to the determination of the mechanisms of changes in the dynamic complexity of the patterns of impulse activity of nociceptors. As a result of the study of the mechanisms of changes in the dynamic complexity of the patterns of impulse activity of nociceptive neurons when the antinociceptive response occurs, it was found that the change in this complexity is based on rearrangements in the temporal organization of patterns due to bifurcations of stationary states and limit cycles, leading to the appearance of two types of burst activity. The mechanism of correction of the damaging pain effect is based on the molecular mechanism of suppression of this activity associated with the modification of the activation gating structure of slow sodium NaV1.8 channels under the action of comenic acid, a drug substance of the non-opioid analgesic “Anoceptin”. The methodology for analyzing the considered molecular mechanism can be used in the search for new pharmacological targets for further research related to the development of innovative pharmacological strategies in the correction of pathological conditions.
7
Hari, Riitta, and Aina Puce. "Introduction." In MEG-EEG Primer, edited by Riitta Hari and Aina Puce, 3–12. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190497774.003.0001.
Full textAbstract:
Neuronal communication in the brain is associated with minute electrical currents that give rise to both electrical potentials on the scalp (measurable by means of electroencephalography [EEG]) and magnetic fields outside the head (measurable by magnetoencephalography [MEG]). Both MEG and EEG are noninvasive neurophysiological methods used to study brain dynamics, that is temporal changes in the activation patterns, and sequences in signal progression. Differences between MEG and EEG mainly reflect differences in the spread of electric and magnetic fields generated by the same electric currents in the human brain. This chapter provides an overall description of the main principles of MEG and EEG and provides background for the following chapters in this and subsequent sections.
8
Tripathi, Vishwas, Amaresh Mishra, Yamini Pathak, Aklank Jain, and Hridayesh Prakash. "Pathogenic Role of iNOs+ M1 Effector Macrophages in Fibromyalgia." In Macrophages [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94492.
Full textAbstract:
Fibromyalgia (FM) or Fibromyalgia Syndrome (FMS) is a neurodegenerative disorder causing musculoskeletal pain, tenderness, stiffness, fatigue, and sleep disorder in the body. It is one of the most common chronic pain conditions, affecting about 6% of the world population. Being refractory, till date, no specific treatment of this disease is available. Accumulating evidences over the last few decades indicate that proinflammatory macrophages, cytokines, & chemokines as the key players in this disease. Recent findings suggest activation of Microglial cells and associated pro-inflammatory signals as one of the major causes of chronic pain in patients suffering from fibromyalgia. Increased density of iNOs/CD68+ M1 effector macrophages has been associated with neuropathic pain models. In light of this, depletion of these pro-inflammatory macrophages has been shown to reduce sensitivity to neuropathic pain. On the other hand, modulating pattern of AGEs (Advanced Glycation End-Products) can also contribute to inactivation of macrophages. These findings strongly suggest that macrophages are critical in both inflammatory and neuropathic pain. Therefore, this chapter highlights the impact of macrophage plasticity in various immunopathological aspects of fibromyalgia.
9
Hong Chin, Wei, Naoyuki Kubota, and Chu Kiong Loo. "An Episodic-Procedural Semantic Memory Model for Continuous Topological Sensorimotor Map Building." In Cognitive Robotics [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104818.
Full textAbstract:
For humans to understand the world around them, learning and memory are two cognitive processes of the human brain that are deeply connected. Memory allows information to retain and forms an experiences reservoir. Computational models replicating those memory attributes can lead to the practical use of robots in everyday human living environments. However, constantly acquiring environmental information in real-world, dynamic environments has remained a challenge for many years. This article proposes an episodic-procedure semantic memory model to continuously generate topological sensorimotor maps for robot navigation. The proposed model consists of two memory networks: i) episodic-procedural memory network (EPMN) and ii) semantic memory network (SMN). The EPMN comprises an Incremental Recurrent Kernel Machines (I-RKM) that clusters incoming input vectors as nodes and learns the activation patterns of the nodes for spatiotemporal encoding. The SMN then takes neuronal activity trajectories from the EPMN and task-relevant signals to update the SMN and produce more compact representations of episodic experience. Thus, both memory networks prevent catastrophic forgetting by constantly generating nodes when the network meets new inputs or updating node weights when the incoming input is similar to previously learned knowledge. In addition, idle or outlier nodes will be removed to preserve memory space.
10
Saltzman, W. Mark. "Cell Migration." In Tissue Engineering. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195141306.003.0012.
Full textAbstract:
Cell migration is crucial to the life of unicellular and multicellular organisms. Unicellular organisms migrate to find food and avoid predators; this migration can occur by swimming through a fluid, which is achieved by flagellar or ciliary beating (exemplified by E. coli or Paramecium, respectively), or crawling along a surface (as in amoebae). In multicellular organisms, migration of a particular cell population is often a component of complex multicellular behaviors including tumor invasion and metastasis, embryogenesis, angiogenesis, and immune responses. In both cases, the speed and pattern of migration are determined by the nature of the cell and by chemicals (both soluble and surface-bound) in the environment. Since cell migration is critical in the formation or regeneration of tissues, a clearer understanding of the dynamics of cell migration would greatly enhance our ability to design materials and processes for tissue engineering. Cell migration is a fundamental mechanism for forming of structures within developing embryos. Accordingly, the migration of cells during embryogenesis is under exquisite control; development of tissue structure and cell migration are interdependent. Chapter 3 discussed limb regeneration in salamanders, a process in which positional gradients of cell adhesion influence cell migration and, ultimately, tissue structure. Similarly, the rate and migration of myogenic cells from the somitic mesoderm is influenced by the presence of local signals in the form of diffusible factors and extracellular matrix composition. These local signals are also produced by cells, with the result that cells throughout the developing limb (which are present in a particular arrangement or tissue structure) control and coordinate the migration of myogenic cells by secretion of activating factors and expression or organization of extracellular matrix molecules. A better understanding of the mechanisms underlying cell migration in the embryo, and the strategies that nature uses to control migration, will almost certainly provide inspiration for tissue engineering. Cell migration underlies many important physiological functions in adults. For example, the immune system, with its widely dispersed ensemble of B and T cells, relies heavily on the coordinated migration of individual cells to patrol the body and to provide opportunities for cell–cell interaction.
Conference papers on the topic "Signal activation pattern"
1
Huang, Ziyin, and Wing-Kuen Ling. "Design of the Codewords for Performing the Pattern Recognitions via a Set of Perceptrons with the Domains of These Activation Functions Have More Than Two Pieces." In 2019 IEEE 4th International Conference on Signal and Image Processing (ICSIP). IEEE, 2019. http://dx.doi.org/10.1109/siprocess.2019.8868915.
Full text
2
Rendu, F., T. Hovig, P. Marche, M. Lebret, D. Tenza, J. Maclouf, J. P. Caen, and S. Levy-Toledano. "MEMBRANE SIGNAL TRANSDUCTION IN PLATELETS WITH ALTERED RELEASE REACTION." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644746.
Full textAbstract:
The process of signal transduction during thrombin-induced activation was studied in pathological platelets characterized by a defect in a specific storage granule, i.e. from Hermansky-Pudlak syndrome (HPS) and from Grey-Platelet Syndrome (GPS). HPS platelets exhibited an apparently normal ultrastructure except for a decreased number of dense bodies. Grey platelets showed marked vacuolization and an almost total absence of alpha-granules. During thrombin stimulation both types of platelets showed the same tendency of centralization of the organelles present indicating that neither type of granule is a prerequisite for this ring-like structure.However this granule centralization was clearly delayed in GPS where it occurred 15 sec after thrombin addition instead of 5 sec in normal platelets. The transducing system involving phosphoinositides specific phospholipase C was observed in platelets lacking dense bodies (HPS) but the phosphatidyl 4,5 bisphosphate(PIP2 )breakdown in 32P-prelabelled platelets was measurable at 202 sec instead of 10 sec in normal platelets. No ch activity was detectable at any time in grey platelets. 32P-phosphatidate (PA) formation was subnormal in HPS platelets and normal in grey platelets. Phosphorylation pattern of myosin light chain (P20) and of 43K protein (P43) were normal in HPS platelets and markedly reduced in grey platelets, being less than half of the normal during the first 15 sec and remaining subnormal even after complete aggregation. The release of constituents from the present granules and the thromboxane formation were lower than in normal platelets in all cases. In conclusions, (i) alpha-granules but not dense bodies may play a key role in the activation of the PIP2 specific phospholipase C,(ii) PA formation does not always correlate with phosphoinositide metabolism and could originate from another pool of diacylglycerol,(iii) complete phosphorylations of both P20 and P43 may not be sufficient to stimulate a normal release, and (iv) end products such as thromboxanes and released ADP accelerate and reinforce platelet responses.
3
Kornev, Denis, Roozbeh Sadeghian, Stanley Nwoji, Qinghua He, Amir Gandjbbakhche, and Siamak Aram. "Machine Learning-Based Gaming Behavior Prediction Platform." In 13th International Conference on Applied Human Factors and Ergonomics (AHFE 2022). AHFE International, 2022. http://dx.doi.org/10.54941/ahfe1001826.
Full textAbstract:
Brain disorders caused by Gaming Addiction drastically increased due to the rise of Internet users and Internet Gaming auditory. Driven by such a tendency, in 2018, World Health Organization (WHO) and the American Medical Association (AMA) addressed this problem as a “gaming disorder” and added it to official manuals. Scientific society equipped by statistical analysis methods such as t-test, ANOVA, and neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and electroencephalography (EEG), has achieved significant success in brain mapping, examining dynamics and patterns in different conditions and stages. Nevertheless, more powerful, self-learning intelligent algorithms are suitable not only to evaluate the correlation between gaming addiction patterns but also to predict behavior and prognosis brain response depending on the addiction severity. The current paper aims to enrich the knowledge base of the correlation between gaming activity, decision-making, and brain activation, using Machine Learning (ML) algorithms and advanced neuroimaging techniques. The proposed gaming behavior patterns prediction platform was built inside the experiment environment composed of a Functional Near-Infrared Spectrometer (fNIRS) and the computer version of Iowa Gambling Task (IGT). Thirty healthy participants were hired to perform 100 cards selection while equipped with fNIRS. Thus, accelerated by IGT gaming decision-making process was synchronized with changes of oxy-hemoglobin (HbO) levels in the human brain, averaged, and investigated in the left and the right brain hemispheres as well as different psychosomatic conditions, conditionally divided by blocks with 20 card trials in each: absolute unknown and uncertainty in the first block, “pre-hunch” and “hunch” in the second and third blocks, and conceptuality and risky in the fourth and fifth blocks. The features space was constructed around the HbO signal, split by training and tested in two proportions 70/30 and 80/20, and drove patterns prediction ML-based platform consisted of five mechanics, such as Multiple Regression, Classification and Regression Trees (CART), Support Vector Machine (SVM), Artificial Neural Network (ANN), and Random Forest. The algorithm prediction power was validated by the 5- and 10-fold cross-validation method and compared by Root Mean Squared Error (RMSE) and coefficient of determination (R Squared) metrics. Indicators of “the best” fit model, lowest RMSE, and highest R Squared were determined for each block and both brain hemispheres and used to make a conclusion about prediction accuracy: SVM algorithm with RBF kernel, Random Forest, and ANN demonstrated the best accuracy in most cases. Lastly, “best fit” classifiers were applied to the testing dataset and finalized the experiment. Hence, the distribution of gaming score was predicted by five blocks and both brain hemispheres that reflect the decision-making process patterns during gaming. The investigation showed increasing ML algorithm prediction power from IGT block one to five, reflecting an increasing learning effect as a behavioral pattern. Furthermore, performed inside constructed platform simulation could benefit in diagnosing gaming disorders, their patterns, mechanisms, and abnormalities.
4
Hui Zhou, Haoshi Zhang, Yingying Wang, Guanglin Li, Hui Wang, Ning Ji, and Shixiong Chen. "Investigation of tibialis anterior muscle activation patterns during walking on different terrains." In 2015 IET International Conference on Biomedical Image and Signal Processing (ICBISP 2015). Institution of Engineering and Technology, 2015. http://dx.doi.org/10.1049/cp.2015.0794.
Full text
5
Chiriac, Victor, and Tien-Yu Tom Lee. "Thermal Performance Evaluation and Enhancement for an Automotive Wireless Application Incorporating Multiple Dynamic Heat Sources." In ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33705.
Full textAbstract:
A detailed transient thermal study for a Remote Keyless Entry System with dynamic heat sources is performed using numerical simulations. The SmartMOS-type device is packaged in a 54 lead SOIC (small outline IC) package with an exposed copper slug. The package is attached to a 4-layer PCB with thermal vias embedded in the board. The challenge resides in the transient thermal interaction between several dynamic heat sources (channels), activated in a sequential fashion following different powering profiles and patterns. The main purpose of the device is to wirelessly provide a communication path between the remote and the receiver placed in the car, so the distance and the signal strength between the two are paramount for an optimal operation. The signal strength is directly associated with the voltage (and associated powering) levels. Several operating scenarios are evaluated by modifying the system design (thermal via pattern) and varying both power dissipation and duration levels. The study starts with just one channel dissipating power, followed by activating the entire dynamic system comprised of six channels dissipating each powers reaching up to 22W at different time intervals. The transient thermal behavior of each source is analyzed during the process. Results indicate that the system dissipating over 14V exceeds the thermal budget (150C) after only 3 powering cycles. Based on the analysis of the complex temperature fields for the multiple dynamic source system, the authors identify alternative power profiles to improve the thermal performance of the overall wireless system, by splitting the power in selective channels and by modifying the power sequence. Several additional cases are further investigated, and the optimized power profiles indicate that they satisfy the thermal budget under various operating conditions and several multiple cycles, while still maintaining the device voltage at 14V levels. A thorough study of the transient patterns and needed system improvements are included.
6
Fleming, Maxwell, Joel Hubbard, Kwang J. Kim, and Kam K. Leang. "Mitigating IPMC Back-Relaxation Effect Through Controlled Activation of Patterned Electrodes." In ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/smasis2011-4970.
Full textAbstract:
With low driving voltage (<5V) and the ability to be operated in aqueous environments, ionic polymer-metal composite (IPMC) materials are quickly gaining attention for use in underwater applications. There are, however, drawbacks to IPMCs, including the “back relaxation” effect. Specifically, when subjected to a DC input (or an excessively slow dynamic input), the IPMC actuator will slowly relax back toward its original position. There is debate over the physical mechanism of back relaxation, although one prevalent theory describes an initial current, caused by the electrostatic forces of the charging electrodes, which drives water molecules across the ion-exchange membrane and deforms the IPMC. Once the electrodes are fully charged, however, the dominant element of the motion is the osmotic pressure, driving the water molecules back to equilibrium, thus causing back relaxation. A new method to mitigate back relaxation is proposed, taking advantage of controlled activation of patterned (sectored) electrodes on the IPMC. Whereas previous approaches to correct back relaxation rested on an increase of input voltage which can lead to electrolysis, subsequently damaging the material, this method involves only proper control of isolated electrodes to compensate for the back relaxation and does not require sensor feedback. An electromechanical model of the actuator is used to guide the design of these input signals, and the feasibility of using electrode patterning to mitigate back relaxation is demonstrated. Without reaching electrolysis, an IPMC is able to maintain its position for approximately 30 seconds. Compared to a simple step response, the rate of relaxation is reduced by 94% and the maximum error is reduced by 64%.
7
Páez, Francisco Javier, Ángel Losada, and Juan José Herrero. "Improvement of the AEB activation algorithm based on the pedestrian reaction." In FISITA World Congress 2021. FISITA, 2021. http://dx.doi.org/10.46720/f2021-pif-073.
Full textAbstract:
"This work is an initial activity in the OPREVU project. This project, funded by the Spanish Ministry of Science and Innovation, is aimed at the use of Virtual Reality (VR) and Artificial Intelligence tools to allow the extraction of Vulnerable Road Users (VRU) behaviour patterns in the event of pedestrian collisions, in order to optimize the Autonomous Emergency Braking (AEB) technologies, incorporated in the new generations of commercial vehicles. With the aim of developing and optimizing the current pedestrian identification systems, vehicle tests are performed on INSIA test track with different vehicles to analyse the behaviour of their AEB systems. These systems are equipped with a Lidar and a camera, whose joint operation allows detecting the proximity of the pedestrian and obtaining variables of interest to assess the automatic intervention of the braking system. The tests are inspired by the CPNA50 and CPNA25 tests, carried out by EURONCAP to validate and certify AEB systems. The reference variables are the TTC (Time-to-collision) and the TFCW. FCW (Forward Collision Warning) is a visual and acoustic signal that appears as a warning light or digitally on the instrument panel and warns of the presence of an obstacle in the vehicle's path, and TFCW is calculated from the sum of the driver's average reaction time and the time to stop if the driver applies pressure on the brake pedal until full detection. On the other hand, TTC is the time calculated from the distance and relative speed of the vehicle with respect to the pedestrian. If the TTC is less than TFCW, the system intervenes. By means of the CARSIM© simulation tool (vehicle-pedestrian-road), it is attainable to modify certain boundary parameters, such as the initial conditions of movement of the pedestrian and the vehicle, as well as their initial relative disposition at the beginning of each test. Along these lines, the virtual model incorporates reactions patterns for the pedestrian, such as stopping, running, or changing direction while crossing the road. These reaction patterns are defined by means of VR tests. The CARSIM© vehicle model integrates the fusion of camera and LiDAR data, and an operating algorithm to control the AEB activation. Using Machine Learning techniques, it is feasible to breed vehicle models based on behavioural patterns from the values obtained in the real tests, and to find out the correlation between the corresponding TTC and TFCW values with parameters measured by the calibration equipment, such as: the maximum speed and the time in which it is reached, the initial relative distance and the relative distance at the moment of AEB activation, or the average deceleration from the start of braking, among others. Hence, the data obtained on the INSIA test tracks allow the virtual models to be validated. Furthermore, the novelty of the approach is to consider the pedestrian reactions just before collision, extracted through users’ experiments made in ad-hoc VR environment, and to generate a more optimised and robust logic with a greater capacity for anticipation."
8
Ribeiro, Estela, and Carlos Eduardo Thomaz. "A multivariate statistical analysis of EEG signals for differentiation of musicians and non-musicians." In XV Encontro Nacional de Inteligência Artificial e Computacional. Sociedade Brasileira de Computação - SBC, 2018. http://dx.doi.org/10.5753/eniac.2018.4442.
Full textAbstract:
It is possible to reveal whether a subject received musical training through the neural activation patterns induced in response to music listening. We are particularly interested in analyzing the brain data on a global level, considering its activity registered in electroencephalogram electrodes signals. Our experiments results, with 13 musicians and 12 non-musicians who listened the song Hungarian Dance No 5 from Johannes Brahms, have shown that is possible to differentiate musicians and non-musicians with high classification accuracy (88%). Given this multivariate statistical framework, it has also been possible to highlight the most expressive and discriminant changes in the participants brain according to the acoustic features extracted from the audio.
9
Mitra, S., M. O'Boyle, E. Corona, B. Li, F. Afrin, B. Nutter, M. Baker, R. Pal, B. Ghosh, and T. Karp. "Generating structure-function correlations by ICA- based mapping of activation patterns on co-registered fMRI and FA-DTI data." In 2008 42nd Asilomar Conference on Signals, Systems and Computers. IEEE, 2008. http://dx.doi.org/10.1109/acssc.2008.5074648.
Full text
10
David, J. L., M. Lambrichts, and M. T. Closon. "INFRACLINIC ACTIVATION OF PLATELETS AND FIBRIN FORMATION IN CANCER PATIENTS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643198.
Full textAbstract:
Thromboembolism has been frequently reported in cancer patients, mainly in cases with solid tumors. Besides in several animal models, fibrin deposition around the tumor and platelet aggre gates appear to be involved in invasion and metastasis. This study was aimed at evaluating the extent of in vivo platelet activation and fibrin formation in several kinds of human cancer. We excluded from this study patients whose blood was sampled with difficulty as well as those having clinical evidence of thrombosis or embolism, those with thrombocytopenia, increased fibrinogen degradation products or biological pattern of disseminated intravascular coagulation. Fibrinopeptide A (fpA) and β-thrombo-globulin (β-tg) were determined by RIA. Free platelet count ratio (PCR) was determined on whole blood samples as an index of circulating aggregates. Usual coagulation tests, antithrombin III activity, protein C plasma level, F VIII related antigen (F VIII RAG), F VIII Ristocetin cofactor (F VIII RCF) and F VIII procoagulant activity (F VIII C) were also determined.It was found that in more than fifty percent of patients, fpA was significantly increased above the upper reference limit. Cases with increased B-tg were less frequent. Separate increases in β-tg or fpA levels were often observed. PCR remained within the reference values in almost all patients. F VIII RAG, RCF and C were usually above 150 % of the reference mean.We conclude that platelet release and fibrinoformation frequently occur in cancer patients showing no sign of thrombotic process. Increased level of fpA with normal plasma β-tg level suggests that thrombin generation occurs only in the extravascular compart ment, probably next to the tumoral tissues. Increased levels of plasma β-tg with normal fpA levels may result from platelet activation by other stimuli than thrombin. It must be emphasized that normal PCR does not exclude the presence of fibrinous circulating aggregates which cannot be dispersed by EDTA. High F VIII activities may be due to the release of the von Willebrand factor from tumoral vessels.
Reports on the topic "Signal activation pattern"
1
Sessa, Guido, and Gregory B. Martin. molecular link from PAMP perception to a MAPK cascade associated with tomato disease resistance. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597918.bard.
Full textAbstract:
The research problem: The detection of pathogen-associated molecular patterns (PAMPs) by plant pattern recognition receptors (PRRs) is a key mechanism by which plants activate an effective immune response against pathogen attack. MAPK cascades are important signaling components downstream of PRRs that transduce the PAMP signal to activate various defense responses. Preliminary experiments suggested that the receptor-like cytoplasmickinase (RLCK) Mai5 plays a positive role in pattern-triggered immunity (PTI) and interacts with the MAPKKK M3Kε. We thus hypothesized that Mai5, as other RLCKs, functions as a component PRR complexes and acts as a molecular link between PAMP perception and activation of MAPK cascades. Original goals: The central goal of this research was to investigate the molecular mechanisms by which Mai5 and M3Kε regulate plant immunity. Specific objectives were to: 1. Determine the spectrum of PAMPs whose perception is transmitted by M3Kε; 2. Identify plant proteins that act downstream of M3Kε to mediate PTI; 3. Investigate how and where Mai5 interacts with M3Kε in the plant cell; 4. Examine the mechanism by which Mai5 contributes to PTI. Changes in research directions: We did not find convincing evidence for the involvement of M3Kε in PTI signaling and substituted objectives 1 and 3 with research activities aimed at the analysis of transcriptomic profiles of tomato plants during the onset of plant immunity, isolation of the novel tomato PRR FLS3, and investigation of the involvement of the RLCKBSKs in PTI. Main achievements during this research program are in the following major areas: 1. Functional characterization of Mai5. The function of Mai5 in PTI signaling was demonstrated by testing the effect of silencing the Mai5 gene by virus-induced gene silencing (VIGS) experiments and in cell death assays. Domains of Mai5 that interact with MAPKKKs and subcellular localization of Mai5 were analyzed in detail. 2. Analysis of transcriptional profiles during the tomato immune responses to Pseudomonas syringae (Pombo et al., 2014). We identified tomato genes whose expression is induced specifically in PTI or in effector-triggered immunity (ETI). Thirty ETI-specific genes were examined by VIGS for their involvement in immunity and the MAPKKK EPK1, was found to be required for ETI. 3. Dissection of MAP kinase cascades downstream of M3Kε (Oh et al., 2013; Teper et al., 2015). We identified genes that encode positive (SGT and EDS1) and negative (WRKY1 and WRKY2) regulators of the ETI-associated cell death mediated by M3Kε. In addition, the MKK2 MAPKK, which acts downstream of M3Kε, was found to interact with the MPK3 MAPK and specific MPK3 amino acids involved interaction were identified and found to be required for induction of cell death. We also identified 5 type III effectors of the bacterial pathogen Xanthomonaseuvesicatoria that inhibited cell death induced by components of ETI-associated MAP kinase cascades. 4. Isolation of the tomato PRR FLS3 (Hind et al., submitted). FLS3, a novel PRR of the LRR-RLK family that specifically recognizes the flagellinepitope flgII-28 was isolated. FLS3 was shown to bind flgII-28, to require kinase activity for function, to act in concert with BAK1, and to enhance disease resistance to Pseudomonas syringae. 5. Functional analysis of RLCKs of the brassinosteroid signaling kinase (BSK) family.Arabidopsis and tomato BSKs were found to interact with PRRs. In addition, certain ArabidospsisBSK mutants were found to be impaired in PAMP-induced resistance to Pseudomonas syringae. Scientific and agricultural significance: Our research activities discovered and characterized new molecular components of signaling pathways mediating recognition of invading pathogens and activation of immune responses against them. Increased understanding of molecular mechanisms of immunity will allow them to be manipulated by both molecular breeding and genetic engineering to produce plants with enhanced natural defense against disease.
2
Sessa, Guido, and Gregory Martin. MAP kinase cascades activated by SlMAPKKKε and their involvement in tomato resistance to bacterial pathogens. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7699834.bard.
Full textAbstract:
The research problem: Pseudomonas syringae pv. tomato (Pst) and Xanthomonas campestrispv. vesicatoria (Xcv) are the causal agents of tomato bacterial speck and spot diseases, respectively. These pathogens colonize the aerial parts of the plant and cause economically important losses to tomato yield worldwide. Control of speck and spot diseases by cultural practices or chemicals is not effective and genetic sources of resistance are very limited. In previous research supported by BARD, by gene expression profiling we identified signaling components involved in resistance to Xcvstrains. Follow up experiments revealed that a tomato gene encoding a MAP kinase kinase kinase (MAPKKKe) is required for resistance to Xcvand Pststrains. Goals: Central goal of this research was to investigate the molecular mechanisms by which MAPKKKεand associated MAP kinase cascades regulate host resistance. Specific objectives were to: 1. Determine whether MAPKKKεplays a broad role in defense signaling in plants; 2. Identify components of MAP kinase cascades acting downstream of MAPKKKε; 3. Determine the role of phosphorylation-related events in the function of MAPKKKε; 4. Isolate proteins directly activated by MAPKKKε-associatedMAPK modules. Our main achievements during this research program are in the following major areas: 1. Characterization of MAPKKKεas a positive regulator of cell death and dissection of downstream MAP kinase cascades (Melech-Bonfil et al., 2010; Melech-Bonfil and Sessa, 2011). The MAPKKKεgene was found to be required for tomato resistance to Xcvand Pstbacterial strains and for hypersensitive response cell death triggered by different R gene/effector gene pairs. In addition, overexpression analysis demonstrated that MAPKKKεis a positive regulator of cell death, whose activity depends on an intact kinase catalytic domain. Epistatic experiments delineated a signaling cascade downstream of MAPKKKεand identified SIPKK as a negative regulator of MAPKKKε-mediated cell death. Finally, genes encoding MAP kinase components downstream of MAPKKKεwere shown to contribute to tomato resistance to Xcv. 2. Identification of tomato proteins that interact with MAPKKKεand play a role in plant immunity (Oh et al., 2011). We identified proteins that interact with MAPKKKε. Among them, the 14-3-3 protein TFT7 was required for cell death mediated by several R proteins. In addition, TFT7 interacted with the MAPKK SlMKK2 and formed homodimersin vivo. Thus, TFT7 is proposed to recruit SlMKK2 and MAPKKK client proteins for efficient signal transfer. 3. Development of a chemical genetic approach to identify substrates of MAPKKKε-activated MAP kinase cascades (Salomon et al., 2009, 2011). This approach is based on engineering the kinase of interest to accept unnatural ATP analogs. For its implementation to identify substrates of MAPKKKε-activated MAP kinase modules, we sensitized the tomato MAP kinase SlMPK3 to ATP analogs and verified its ability to use them as phosphodonors. By using the sensitized SlMPK3 and radiolabeled N6(benzyl)ATP it should be possible to tag direct substrates of this kinase. 4. Development of methods to study immunity triggered by pathogen-associated molecular patterns (PAMPs) in tomato and N. benthamiana plants (Kim et al., 2009; Nguyen et al. 2010). We developed protocols for measuring various PTI-associatedphenotypes, including bacterial populations after pretreatment of leaves with PAMPs, induction of reporter genes, callose deposition at the cell wall, activation of MAP kinases, and a luciferase-based reporter system for use in protoplasts. Scientific and agricultural significance: Our research activities discovered and characterized a signal transduction pathway mediating plant immunity to bacterial pathogens. Increased understanding of molecular mechanisms of immunity will allow them to be manipulated by both molecular breeding and genetic engineering to produce plants with enhanced natural defense against disease. In addition, we successfully developed new biochemical and molecular methods that can be implemented in the study of plant immunity and other aspects of plant biology.