Biology subjects

Liu, L.

Publications and source records attributed to Liu, L..

At least 847 records · Page 47Linked to original sources

bioRxiv2019

Mining the human tonsillar microbiota as autoimmune modulator

Palatine tonsils are important lymphoid organs featuring constant cross-talks between the commensal microorganisms and immune system, and have been implicated as critical autoimmunity origins for immune-related diseases, including rheumatoid arthritis (RA), a common autoimmune disorder. However, there was no evidence to show link between tonsillar microbiota and RA. Here, we identified a significant dysbiosis of RA tonsillar microbiota, with loss of Streptococcus salivarius and its functional molecules salivaricins (a type of antibacterial peptides). Consistent with the niche-preference, S. salivarius and salivaricins administrated intranasally or intraorally conferred prophylactic and therapeutic efficacies against experimental arthritis. Moreover, we demonstrated, for the first time, that S. salivarius and salivaricins exerted immunosuppressive capacities via inhibiting CD4+effector T cell subsets and autoantibody production in mice and human. These results uncover a communication between tonsillar microbiota and host autoimmunity, and identify the active components from tonsillar microbes in modulating immune homeostasis.\n\nOne sentence summaryTonsillar microbiota regulate host autoimmunity via antibacterial peptides

microbiology↗

bioRxiv2019

The PRMT7-dependent methylation of shank2 modulates invasion-proliferation switching during breast cancer metastasis

Invasiveness of cancer cells is associated with proliferation inhibition in multiple types of cancers. Here, we identified the pivotal roles of Arginine methyltransferase PRMT7 in promoting invasion and attenuating proliferation of breast cancer cells. PRMT7 exerted its functions through binding to the scaffold protein shank2 to induce the di-methylation of shank2 at R240. Shank2 R240 methylation exposed ANK domain by disrupting its SPN-ANK domain blockade. Moreover, shank2 R240 methylation rendered recruitment of FAK that elicited the FAK auto-phosphorylation, which consequently augmented the shank2-dependent migration and invasion of breast cancer cells. On the other hand, the shank2 R240 methylation impeded proliferation of breast cancer cells by antagonizing the Ras-Raf binding via tethering the mono-ubiquitinated H-Ras. These findings characterize the PRMT7-dependent shank2 methylation as a key player in mediating reciprocal switching between invasion and proliferation, also point to the value of shank2 R240 methylation as a target for tumour metastasis treatment strategies.

cancer biology↗

bioRxiv2019

Rapid pacing by circulating traveling waves improves maturation of hiPSC-derived cardiomyocytes in self-organized tissue ring

Directed differentiation methods allow acquisition of high-purity cardiomyocytes (CMs) differentiated from human induced pluripotent stem cells (hiPSCs); however, their immaturity characteristic limits their application for drug screening and regenerative therapy. The rapid electrical pacing of cardiomyocytes have been used for efficiently promoting the maturation of cardiomyocytes, here we describe a simple device in modified culture plate on which hiPSC-derived CMs (hiPSC-CMs) can form three-dimensional self-organized tissue rings (SOTRs). Using calcium imaging, we show that within the ring, traveling waves (TWs) of action potential spontaneously originated and ran robustly at a frequency up to 4 Hz. After 2 weeks, SOTRs with TW training showed matured features including structural organization, increased cardiac-specific gene expression, enhanced Ca2+-handling properties, an increased oxygen-consumption rate, and enhanced contractile force. We subsequently used a mathematical model to interpret the origination, propagation, and long-term behavior of the TWs within the SOTRs. This new idea for spontaneous hiPSC-CM maturation also has potential for pacing the electrical excitable cells such as neuron and retina cells for various applications.

bioengineering↗

bioRxiv2019

Contextual Classifications of Cancer Driver Genes

Functions of cancer driver genes depend on cellular contexts that vary substantially across tissues and organs. Distinguishing oncogenes (OGs) and tumor suppressor genes (TSGs) for each cancer type is critical to identifying clinically actionable targets. However, current resources for context-aware classifications of cancer drivers are limited. In this study, we show that the direction and magnitude of somatic selection of missense and truncating mutations of a gene are suggestive of its contextual activities. By integrating these features with ratiometric and conservation measures, we developed a computational method to categorize OGs and TSGs using exome sequencing data. This new method, named genes under selection in tumors (GUST) shows an overall accuracy of 0.94 when tested on manually curated benchmarks. Application of GUST to 10,172 tumor exomes of 33 cancer types identified 98 OGs and 179 TSGs, >70% of which promote tumorigenesis in only one cancer type. In broad-spectrum drivers shared across multiple cancer types, we found heterogeneous mutational hotspots modifying distinct functional domains, implicating the synchrony of convergent and divergent disease mechanisms. We further discovered two novel OGs and 28 novel TSGs with high confidence. The GUST program is available at https://github.com/liliulab/gust. A database with pre-computed classifications is available at https://liliulab.shinyapps.io/gust

bioinformatics↗

bioRxiv2019

Endoplasmic reticulum associated degradation preserves hematopoietic stem cell quiescence and self-renewal by restricting mTOR activity

Many tissue-specific stem cells require quiescence to sustain stem cell pool and maintain lifelong tissue integrity. It remains unclear whether protein quality control is required for stem cells in quiescence when RNA content, protein synthesis and metabolic activities are significantly reduced. Here, we report that endoplasmic reticulum associated degradation (ERAD) is required to preserve the function of quiescent hematopoietic stem cells (HSC). The Sel1L/Hrd1 ERAD genes are enriched in the quiescent and inactive HSCs, and conditional knockout of Sel1L in hematopoietic tissues drives HSCs to hyper-proliferation which leads to reduced self-renewal and HSC depletion. ERAD deficiency induces a non-apoptotic ER stress and activates unfolded protein response (UPR). Furthermore, Sel1L knockout leads to mTOR activation, and mTOR inhibition rescues the HSC defects in Sel1L knockout mice. Protein quality control is, therefore, tightly regulated and actively engaged in quiescent HSCs. Sel1L/Hrd1 ERAD maintains HSC quiescence and self-renewal via restricting mTOR activity.

cell biology↗

bioRxiv2019

Evolutionary decomposition of genetic effects

Genic functions have long been confounded by pleiotropic mutational effects. To understand such genetic effects, we examine HAP4, a well-studied transcription factor in Saccharomyces cerevisiae that functions by forming a tetramer with HAP2, HAP3, and HAP5. Deletion of HAP4 results in highly pleiotropic gene expression responses, some of which are clustered in related cellular processes (clustered effects) while most are distributed randomly across diverse cellular processes (distributed effects). Strikingly, the distributed effects that account for much of HAP4 pleiotropy tend to be non-heritable in a population, suggesting they have little evolutionary consequences. Indeed, these effects are poorly conserved in closely related yeasts. We further show substantial overlaps of clustered effects, but not distributed effects, among the four genes encoding the HAP2/3/4/5 tetramer. This pattern holds for other biochemically characterized yeast protein complexes or metabolic pathways. Examination of a set of cell morphological traits of the deletion lines yields consistent results. Hence, only some gene deletion effects support related biochemical understandings with the rest being pleiotropic and evolutionarily decoupled from the genes normal functions.

genetics↗

bioRxiv2019

Complete single neuron reconstruction reveals morphological diversity in molecularly defined claustral and cortical neuron types

Ever since the seminal findings of Ramon y Cajal, dendritic and axonal morphology has been recognized as a defining feature of neuronal types. Yet our knowledge concerning the diversity of neuronal morphologies, in particular distal axonal projection patterns, is extremely limited. To systematically obtain single neuron full morphology on a brain-wide scale, we established a platform with five major components: sparse labeling, whole-brain imaging, reconstruction, registration, and classification. We achieved sparse, robust and consistent fluorescent labeling of a wide range of neuronal types by combining transgenic or viral Cre delivery with novel transgenic reporter lines. We acquired high-resolution whole-brain fluorescent images from a large set of sparsely labeled brains using fluorescence micro-optical sectioning tomography (fMOST). We developed a set of software tools for efficient large-volume image data processing, registration to the Allen Mouse Brain Common Coordinate Framework (CCF), and computer-assisted morphological reconstruction. We reconstructed and analyzed the complete morphologies of 1,708 neurons from the striatum, thalamus, cortex and claustrum. Finally, we classified these cells into multiple morphological and projection types and identified a set of region-specific organizational rules of long-range axonal projections at the single cell level. Specifically, different neuron types from different regions follow highly distinct rules in convergent or divergent projection, feedforward or feedback axon termination patterns, and between-cell homogeneity or heterogeneity. Major molecularly defined classes or types of neurons have correspondingly distinct morphological and projection patterns, however, we also identify further remarkably extensive morphological and projection diversity at more fine-grained levels within the major types that cannot presently be accounted for by preexisting transcriptomic subtypes. These insights reinforce the importance of full morphological characterization of brain cell types and suggest a plethora of ways different cell types and individual neurons may contribute to the function of their respective circuits.

neuroscience↗

bioRxiv2019

Metagenomic Next-generation Sequencing of Cerebrospinal Fluid for the Diagnosis of Central Nervous System Infections: A Multicentre Prospective Study

BackgroundInfectious encephalitis and meningitis are often treated empirically without identification of the causative pathogen. Metagenomic next-generation sequencing (mNGS) is a high throughput technology that enables the detection of pathogens independent of prior clinical or laboratory information.\n\nMethodsThe present study was a multicentre prospective evaluation of mNGS of cerebrospinal fluid (CSF) for the diagnosis of suspected central nervous system infections.\n\nResultsA total of 276 patients were enrolled in this study between Jan 1, 2017 and Jan 1, 2018. Identification of an etiologic pathogen in CSF by mNGS was achieved in 101 patients (36.6%). mNGS detected 11 bacterial species, 7 viral species, 2 fungal species, and 2 parasitic species. The five leading positive detections were varicella-zoster virus (17), Mycobacterium tuberculosis (14), herpes simplex virus 1 (12), Epstein-Barr virus (12), and Cryptococcus neoformans (7). False positives occurred in 12 (4.3%) patients with bacterial infections known to be widespread in hospital environments. False negatives occurred in 16 (5.8%) patients and included bacterial, viral and fungal aetiologies.\n\nConclusionsmNGS of CSF is a powerful diagnostic method to identify the pathogen for many central nervous system infections.

genomics↗

bioRxiv2019

Screening and functional analysis of differentially expressed genes in an animal model of EBV-associated lymphomas

Epstein-Barr virus (EBV) is an important human oncogenic virus. This paper is to explore how EBV induce malignant transformation of human lymphocytes and the related mechanism of lymphomagenesis. We have constructed hu-PBL/SCID chimeric mice and established a model of EBV-associated human-derived lymphomas. By using Agilent human whole genome microarray and a series of bioinformatic analyses, a total of 202 differentially expressed genes were screened from the EBV-induced lymphomas in hu-PBL/SCID mice, including 44 up-regulated and 158 down-regulated genes. Calculation of the rank score (RS) values of these genes in the HIPPIE protein interaction networks showed that topoisomerase II alpha (TOP2A), ubiquitin like with PHD and ring finger domains 1 (UHRF1), histone cluster 2 H2B family member E (HIST2H2BE), phosphoglycerate dehydrogenase (PHGDH), vinculin (VCL), insulin-like growth factor 1 receptor (IGF1R), Fos proto-oncogene (FOS), snail family transcriptional repressor 1 (SNAI1), PDZ binding kinase (PBK), and ring finger protein 144B (RNF144B) were the top 10 key node genes of EBV-induced lymphoma. In which, PBK, an up-regulated genes with the highest number of GO annotations, was verified by cellular function experiments and clinical lymphoma samples.\n\nAuthor summaryEB virus is closely associated with human lymphoma and nasopharyngeal carcinoma. Since the susceptible hosts of EBV limit to human and cottontop tammarins, there are no appropriate animal models so far to study the EBV-associated oncogenesis. In our previous experiments, the EBV-associated lymphomas were induced in hu-PBL/SCID chimera (a new humanized mouse model). However, the cellular and molecular mechanisms of malignant transformation of normal human cells and tumor formation induced by EBV remain unclear. In this study, we examined and compared the gene expression profiles of EBV-induced lymphomas and normal human lymphocytes of the same origin in SCID mice. By constructing the gene-function relationship network, we preliminarily found that TOP2A, UHRF1, HIST2H2BE, PHGDH, VCL, IGF1R, FOS, SNAI1, PBK, and RNF144B may be the key genes in EBV-induced lymphomas. These findings suggest that the induction of lymphoma by EBV is a complex process that involves multiple genes and pathways.

cancer biology↗

bioRxiv2019

Ginsenoside Rg1 defenses PC-12 cells against hydrogen peroxide-caused damage via up-regulation of miR-216a-5p

BackgroundSpinal cord injury (SCI) is a destructive trauma accompanying with local injury, half of which cause chronic paralysis. Ginsenoside Rg1 exerts anti-apoptosis and anti-autophagy properties. Therefore, our goal was to study the protective mechanism of Rg1 in attenuating cell injury.\n\nMethodsMiR-216a-5p inhibitor was transfected into PC-12 cells, then cells were pre-treated by Rg1 and treated with 300 M hydrogen peroxide (H2O2) for 24 h. CCK-8 and apoptosis experiments were done to test cell activity and apoptosis respectively. Expression of miR-216a-5p and cell damage relative factors was tested via qRT-PCR and western blot experiments, respectively.\n\nResultsH2O2 induced cell activity suppression, apoptosis and autophagy well at the concentration of 300 M, leading cell injury. Rg1 could attenuate cell injury induced by H2O2 at the working concentration of 200 M that it elevated cell activity, attenuated apoptosis and autophagy and activated PI3K/AKT and AMPK signal pathways. Further, miR-216a-5p was up-regulated by Rg1. Rg1 played its role in relieving cell injury by positively regulating miR-216a-5p.\n\nConclusionOur study demonstrated that Rg1 attenuated H2O2-caused cell injury through positively regulated miR-216a-5p.

biochemistry↗

bioRxiv2019

T Lymphopoiesis from Pluripotent Stem Cells by Defined Transcription Factors at Single Cell Resolution

Achievement of immunocompetent and therapeutic T lymphopoiesis from pluripotent stem cells is a central aim in T cell regenerative medicine. To date, preferentially regenerating T lymphopoiesis in vivo from pluripotent stem cells (PSC) remains a practical challenge. Here we documented that synergistic and transient expression of Runx1 and Hoxa9 restricted in the time window of endothelial to hematopoietic transition and hematopoietic maturation stages induced in vitro from PSC (iR9-PSC) preferentially generated engraftable hematopoietic progenitors capable of homing to thymus and developing into mature T (iT) cells in primary and secondary immunodeficient recipients. Single-cell transcriptome and functional analyses illustrated the cellular trajectory of T lineage induction from PSC, unveiling the T-lineage specification determined at as early as hemogenic endothelial cell stage and identifying the bona fide pre-thymic progenitors. The iT cells distributed normally in central and peripheral lymphoid organs and exhibited abundant TCR{beta} repertoire. The regenerative T lymphopoiesis rescued the immune-surveillance ability in immunodeficient mice. Furthermore, gene-edited iR9-PSC produced tumor-specific-T cells in vivo that effectively eradicated tumor cells. This study provides insight into universal generation of functional and therapeutic T lymphopoiesis from the unlimited and editable PSC source.

immunology↗

bioRxiv2019

Identifying miRNA synergism using multiple-intervention causal inference

BackgroundStudying multiple microRNAs (miRNAs) synergism in gene regulation could help to understand the regulatory mechanisms of complicated human diseases caused by miRNAs. Several existing methods have been presented to infer miRNA synergism. Most of the current methods assume that miRNAs with shared targets at the sequence level are working synergistically. However, it is unclear if miRNAs with shared targets are working in concert to regulate the targets or they individually regulate the targets at different time points or different biological processes. A standard method to test the synergistic activities is to knock-down multiple miRNAs at the same time and measure the changes in the target genes. However, this approach may not be practical as we would have too many sets of miRNAs to test.\n\nResultsIn this paper, we present a novel framework called miRsyn for inferring miRNA synergism by using a causal inference method that mimics the multiple-intervention experiments, e.g. knocking-down multiple miRNAs, with observational data. Our results show that several miRNA-miRNA pairs that have shared targets at the sequence level are not working synergistically at the expression level. Moreover, the identified miRNA synergistic network is small-world and biologically meaningful, and a number of miRNA synergistic modules are significantly enriched in breast cancer. Our further analyses also reveal that most of synergistic miRNA-miRNA pairs show the same expression patterns. The comparison results indicate that the proposed multiple-intervention causal inference method performs better than the single-intervention causal inference method in identifying miRNA synergistic network.\n\nConclusionsTaken together, the results imply that miRsyn is a promising framework for identifying miRNA synergism, and it could enhance the understanding of miRNA synergism in breast cancer.

bioinformatics↗

bioRxiv2019

De-risking drug discovery of intracellular targeting peptides: screening strategies to eliminate false-positive hits

Discovery of false-positive target binding, due to assay interference or aggregation, presents a significant problem for drug discovery programs. These issues may often be unrealized and could lead researchers astray if not subject to independent verification of reproducibility and/or on-target mechanism of action. Although well-documented for small molecules, this issue has not been widely explored for peptide modality. As a case study, we demonstrate that two purported KRas inhibitors, stapled peptide SAH-SOS1A and macrocyclic peptide cyclorasin 9A5, exemplify false-positive molecules - both in terms of their sub-micromolar KRas binding affinities and their on-target cellular activities. We observed that the apparent binding of fluorescein-labeled SAH-SOS1A given by a fluorescence polarization assay is sensitive to detergent. False-positive readouts can arise from peptide adsorption to the surface of microplates. Hence, we used surface plasmon resonance and isothermal titration calorimetry to unambiguously show that both SAH-SOS1A and cyclorasin 9A5 are non-binders for KRas. Thermal shift assay and hydrogen-deuterium exchange mass spectrometry further demonstrate that both peptides destabilize KRas and induce unfolding of the protein. Furthermore, both peptides caused significant release of intracellular lactate dehydrogenase, suggesting that membrane rupture rather than on-target activity is accountable for their reported cytotoxicity. Finally, both peptides exhibited off-target activities by inhibiting the proliferation of U-2 OS and A549 cells, despite their independency of the KRas signaling pathway. Our findings demonstrate the critical need to employ orthogonal binding assays and cellular counter-screens to de-risk false-positive molecules. More rigorous workflows should lead to improved data and help obviate inadvertent scientific conclusions.\n\nSignificance statementFalse positive molecule hits occur frequently in high-throughput screens and can contaminate the scientific literature. This has become an increasingly serious issue in small molecule drug discovery and chemical probe development and it is not surprising that peptides may be similarly prone to assay interference. Using KRas as a target and two known macrocyclic peptide inhibitors as a case study, we clearly show that reporter-free biophysical assays and cellular counter-screens offer the solution to detect and de-risk the potential of false-positive compounds. We further discuss the advantages, limitations and overall strategic importance of such methods.

biochemistry↗

bioRxiv2019

Identification of NAD-dependent xylitol dehydrogenase from Gluconobacter oxydans WSH-003

Gluconobacter oxydans plays important role in conversion of D-sorbitol to L-sorbose, which is an essential intermediate for industrial-scale production of vitamin C. In the fermentation process, some D-sorbitol could be converted to D-fructose and other byproducts by uncertain dehydrogenases. Genome sequencing has revealed the presence of diverse genes encoding dehydrogenases in G. oxydans. However, the characteristics of most of these dehydrogenases remain unclear. Therefore, analyses of these unknown dehydrogenases could be useful for identifying those related to the production of D-fructose and other byproducts. Accordingly, dehydrogenases in G. oxydans WSH-003, an industrial strain used for vitamin C production, were examined. An NAD-dependent dehydrogenase, which was annotated as xylitol dehydrogenase 2, was identified, codon-optimized, and expressed in Escherichia coli BL21 (DE3) cells. The enzyme exhibited high preference for NAD+ as the cofactor, while no activity with NADP+, FAD, or PQQ was noted. Although this enzyme presented high similarity with NAD-dependent xylitol dehydrogenase, it showed high activity to catalyze D-sorbitol to D-fructose. Unlike the optimum temperature and pH for most of the known NAD-dependent xylitol dehydrogenases (30{degrees}C-40{degrees}C and about 6-8, respectively), those for the identified enzyme were 57{degrees}C and 12, respectively. The Km and Vmax of the identified dehydrogenase towards L-sorbitol were 4.92 M and 196.08 M/min, respectively. Thus, xylitol dehydrogenase 2 can be useful for cofactor NADH regeneration under alkaline conditions or its knockout can improve the conversion ratio of D-sorbitol to L-sorbose.\n\nImportanceProduction of L-sorbose from D-sorbitol by Gluconobacter oxydans is the first step for industrial scale production of L-ascorbic acid. G. oxydans contains a lot of different dehydrogenases, among which only several are responsible for the conversion of D-sorbitol to L-sorbose, while others may responsible for the accumulation of byproducts, thus decreased the yield of L-sorbose on D-sorbitol. Therefore, a new xylitol dehydrogenase has been identified from 44 dehydrogenases of G. oxydans. Optimum temperature and pH of the xylitol dehydrogenase are different to most of the known ones. Knock-out of the dehydrogenase may improve the conversion ratio of D-sorbitol to L-sorbose. Besides, the enzyme exhibits high preference for NAD+ and have potential to be used for cofactor regeneration.

bioengineering↗

bioRxiv2019

Acetyl-CoA production by specific metabolites promotes cardiac repair after myocardial infarction via mediating histone acetylation

Myocardial infarction (MI) is accompanied by severe energy deprivation and extensive epigenetic changes. However, how energy metabolism and chromatin modifications are interlinked during MI and heart repair has been poorly explored. Here, we examined the effect of different carbon sources that involved in the major metabolic pathways of acetyl-CoA synthesis on myocardial infarction and found that elevation of acetyl-CoA significantly improved heart function in I/R rats by administration of sodium octanoate (8C). Mechanistically, 8C prevented I/R injury by promoting histone acetylation which in turn activated the expression of antioxidant genes HO1, NQO1 and SOD2 and inhibited cardiomyocyte apoptosis. Furthermore, we identified that 8C-promoted histone acetylation and heart repair were carried out by metabolic enzyme medium-chain acyl-CoA dehydrogenase (MCAD) and histone acetyltransferase Kat2a. Therefore, our results demonstrate that 8C dramatically improves cardiac function through metabolic acetyl-CoA-mediated histone acetylation. This study uncovers an interlinked metabolic/epigenetic network comprising 8C, acetyl-CoA, MCAD, and Kat2a in stimulating histone acetylation and anti-oxidative stress gene expression to combat heart injury.

cell biology↗

bioRxiv2019

TeraVR Empowers Precise Reconstruction of Complete 3-D Neuronal Morphology in the Whole Brain

Neuron morphology is recognized as a key determinant of cell type, yet the quantitative profiling of a mammalian neurons complete three-dimensional (3-D) morphology remains arduous when the neuron has complex arborization and long projection. Whole-brain reconstruction of neuron morphology is even more challenging as it involves processing tens of teravoxels of imaging data. Validating such reconstructions is extremely laborious. We developed TeraVR, an open-source virtual reality annotation system, to address these challenges. TeraVR integrates immersive and collaborative 3-D visualization, interaction, and hierarchical streaming of teravoxel-scale images. Using TeraVR, we produced precise 3-D full morphology of long-projecting neurons in whole mouse brains and developed a collaborative workflow for highly accurate neuronal reconstruction.

neuroscience↗

bioRxiv2019

Exogenous Melatonin accelerates seed germination in cotton(Gossypium hirsutum L.)

Seed germination is considered as the beginning of the spermatophyte lifecycle, as it is a crucial stage in determining subsequent plant growth and development. Although many previous studies have found that melatonin can promote seed germination, the role of melatonin in cotton germination remains unexamined. The main objective of this study is the characterization of potential promotional effects of melatonin (at doses of 0, 10, 20, 50, 100 and 200 M) on cotton seed germination. This experiment demonstrated that low concentrations of melatonin can promote germination, while high concentrations failed to promote germination and even inhibited germination. Together, these results indicate that a 20 M melatonin treatment optimally promotes cotton seed germination. Compared with the control, germination potential (GP), germination rate (GR) and final fresh weight (FW) increased by 16.67%, 12.30% and 4.81% respectively. Although low concentrations of melatonin showed some improvement in vigor index (VI), germination index (GI) and mean germination time (MGT), these effects did not reach significant levels. Antioxidant enzyme activity during seed germination was most prominent under the 20 M melatonin treatment. Superoxide dismutase (SOD) and peroxidase (POD) activities were significantly increased by 10.37-59.73% and 17.79-47.68% compared to the melatonin-free control. Malondialdehyde (MDA) content was reduced by 16.73-40.33%. Two important plant hormones in seed germination were also studied. As melatonin concentration increased, ABA content in seeds decreased first and then increased, and GA3 content showed a diametrically opposite trend, in which the 20 M melatonin treatment was optimal. The 20 M melatonin treatment reduced ABA content in seeds by 42.13-51.68%, while the 20 M melatonin treatment increased GA3 content in seeds to about 1.7-2.5 times that of seeds germinated without melatonin. This study provides new evidence suggesting that low concentrations of melatonin can promote cotton seed germination by increasing the activity of antioxidant enzymes, thereby reducing the accumulation of MDA and regulating plant hormones. This has clear applications for improving the germination rate of cotton seeds using melatonin.

plant biology↗

bioRxiv2019

TMC1 confers a leak conductance to modulate excitability of auditory hair cells in mammals

Hearing sensation relies on the mechano-electrical transducer (MET) channel of cochlear hair cells, in which Transmembrane channel-like 1 (TMC1) and TMC2 have been proposed to be the pore-forming subunits. Meanwhile it has been reported that TMCs regulate other biological processes in a variety of lower organisms ranging from sensations to motor functions. However, it is still an open question whether TMCs play roles other than their function in MET in mammals. In this study, we report that in mouse hair cells TMC1, but not TMC2, provides a background leak conductance, with properties distinct from those of the MET channels. By cysteine substitution, 4 amino acids of TMC1 are characterized critical for the leak conductance. The leak conductance is essential for action potential firing and tonotopic along the cochlear coil. Taken together, our results suggest that TMC1 confers a background leak conductance that modulates membrane excitability in cochlear hair cells.

cell biology↗