Biology subjects

Kannan, M.

Publications and source records attributed to Kannan, M..

3 recordsLinked to original sources

bioRxiv2021

Dual polarity voltage imaging reveals subthreshold dynamics and concurrent spiking patterns of multiple neuron-types

Genetically encoded fluorescent voltage indicators are ideally suited to reveal the millisecond-scale interactions among and between distinct, targeted cell populations. However, current indicator families lack the requisite sensitivity for in vivo multipopulation imaging. We describe high-performance green and red sensors, Ace-mNeon2 and VARNAM2, and their reverse response-polarity variants, pAce and pAceR. Our indicators enable 0.4-1 kHz voltage recordings from >50 neurons per field-of-view in awake mice and [~]30-min continuous imaging in flies. Using dual-polarity multiplexed imaging, we uncovered behavioral state-dependent interactions between distinct neocortical subclasses, as well as contributions to hippocampal field potentials from non-overlapping projection neuronal ensembles. By combining three mutually compatible indicators, we demonstrate concurrent triple-population voltage imaging. Our approach will empower investigations of the dynamic interplay between neuronal subclasses at single-spike resolution. One Sentence SummaryA new suite of voltage sensors enables simultaneous cellular-resolution activity imaging from multiple, targeted neuron-types in awake animals.

neuroscience↗

bioRxiv2021

Induction of soluble platelet activation markers and FXIII deficiency promote COVID-19 severity

IntroductionCoagulation dysfunction and thromboembolism emerge as strong comorbidity factors in severe COVID-19. However, it is unclear when particularly platelet activation markers and coagulation factors dysregulated during the pathogenesis of COVID-19. Here, we sought to assess the levels of coagulation and platelet activation markers at moderate and severe stages of COVID-19 to understand the pathogenesis. MethodsTo understand this, hospitalized COVID-19 patients with (severe cases that required intensive care) or without pneumonia (moderate cases) were recruited. Phenotypic and molecular characterizations were performed employing basic coagulation tests including PT, APTT, D-Dimer and TFPI. The flow cytometry-based multiplex assays were performed to assess FXI, anti-thrombin, prothrombin, fibrinogen, FXIII, P-selectin, sCD40L, plasminogen, tissue-plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and D-Dimer. ResultsThe investigations revealed induction of plasma P-selectin and CD40 ligand (sCD40L) in moderate COVID-19 cases which were significantly abolished with the progression of COVID-19 severity. Moreover, a profound reduction in plasma tissue factor pathway inhibitor (TFPI) and FXIII were identified particularly in the severe COVID-19. Further analysis revealed fibrinogen induction in both moderate and severe patients. Interestingly, an elevated PAI-1 more prominently in moderate, and tPA particularly in severe COVID-19 cases were observed. Particularly, the levels of fibrinogen and tPA directly correlated with the severity of the disease. ConclusionsIn summary, induction of soluble P-selectin, sCD40L, fibrinogen and PAI-1 in moderate COVID-19 cases suggests the activation of platelets and coagulation system before patients require intensive care. These findings would help in designing better thromboprophylaxis to limit the COVID-19 severity.

pathology↗

bioRxiv2021

Proteomic analysis reveals different sets of proteins expressed during high temperature stress in two thermotolerant isolates of Trichoderma

Several species of the soil borne fungus of the genus Trichoderma are known to be versatile, opportunistic plant symbionts, and are the most successful biocontrol agents used in todays agriculture. To be successful in the field conditions, the fungus must endure varying climatic conditions. Studies have indicated that high atmospheric temperature coupled with low humidity is a major limitation for the inconsistent performance of Trichoderma under field conditions. Understanding the molecular modulation associated with such Trichoderma that persist and deliver under abiotic stress condition will aid in exploiting the worth of these organisms for such use. In this study, comparative proteomic analysis using two-dimensional gel electrophoresis (2DE) and matrix-assisted laser desorption/time-of-flight (MALDI-TOF-TOF) mass spectrometry was used to identify proteins associated with thermotolerance in two thermotolerant isolates of Trichoderma--T. longibrachiatum 673, TaDOR673 and T. asperellum 7316, TaDOR7316--and 32 differentially expressed proteins were identified. Sequence homology and conserved domains were used to identify these proteins and to assign probable function to them. Thermotolerant isolate, TaDOR673, seemed to employ the stress signaling MAPK pathways and heat shock response pathways to combat the stress condition whereas the moderately tolerant isolate, TaDOR7316, seemed to adapt to high temperature conditions by reducing the accumulation of mis-folded proteins through unfolded protein response pathway and autophagy. Also, there were unique as well as common proteins that were differentially expressed in the two isolates studied.

molecular biology↗