Pub Date : 2019-04-12DOI: 10.19185/MATTERS.201903000030
Antoine Daviere, Maximilien Sotomski, A. Audibert, P. Carol, S. Hubert, S. Lebreton, S. Louvet-Vallée, J. Pédron, J. Puyaubert, Y. Kraepiel, J. Lacoste
Glyphosate is a widely-used herbicide that is frequently found as a pollutant of soil and water runoffs. Glyphosate toxicity is controversial but a toxic synergy with other molecules could result in deleterious consequences for living organisms and for the human health. Using budding yeast (Saccharomyces cerevisiae) as a eukaryotic model organism, we report here a strong toxic synergy between glyphosate and 2,4-dinitrophenol (DNP), a phenolic compound derived from diesel engine’s combustion and industrial pollutant found frequently in surface water and rainfall. Glyphosate concentrations below 600 mg/L did not affect yeast growth but exhibit dose-dependent toxicity in the presence of non-toxic DNP concentrations (below 1 mM). This so-called ‘cocktail effect’ increases with DNP concentration. Yeast growth is totally abolished in the presence of the highest concentration of both molecules. We explored the implication of oxidative stress in this synergistic effect of glyphosate and DNP, by measuring H2O2 concentrations in the culture media, and by comparing cta1∆/ctt1∆ catalase double-mutant with wild-type yeast. We did not find any glyphosate-DNP enhanced susceptibility for the catalase mutant and did not observe any clear increase of H2O2 in the presence of the pollutant mixture. All these data suggest that the redox homeostasis is not involved in this toxic synergy, that remains to be explained.
{"title":"Synergistic toxicity between glyphosate and 2,4-dinitrophenol on budding yeast is not due to H2O2-mediated oxidative stress","authors":"Antoine Daviere, Maximilien Sotomski, A. Audibert, P. Carol, S. Hubert, S. Lebreton, S. Louvet-Vallée, J. Pédron, J. Puyaubert, Y. Kraepiel, J. Lacoste","doi":"10.19185/MATTERS.201903000030","DOIUrl":"https://doi.org/10.19185/MATTERS.201903000030","url":null,"abstract":"Glyphosate is a widely-used herbicide that is frequently found as a pollutant of soil and water runoffs. Glyphosate toxicity is controversial but a toxic synergy with other molecules could result in deleterious consequences for living organisms and for the human health. Using budding yeast (Saccharomyces cerevisiae) as a eukaryotic model organism, we report here a strong toxic synergy between glyphosate and 2,4-dinitrophenol (DNP), a phenolic compound derived from diesel engine’s combustion and industrial pollutant found frequently in surface water and rainfall. Glyphosate concentrations below 600 mg/L did not affect yeast growth but exhibit dose-dependent toxicity in the presence of non-toxic DNP concentrations (below 1 mM). This so-called ‘cocktail effect’ increases with DNP concentration. Yeast growth is totally abolished in the presence of the highest concentration of both molecules. We explored the implication of oxidative stress in this synergistic effect of glyphosate and DNP, by measuring H2O2 concentrations in the culture media, and by comparing cta1∆/ctt1∆ catalase double-mutant with wild-type yeast. We did not find any glyphosate-DNP enhanced susceptibility for the catalase mutant and did not observe any clear increase of H2O2 in the presence of the pollutant mixture. All these data suggest that the redox homeostasis is not involved in this toxic synergy, that remains to be explained.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"90 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74959754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-11DOI: 10.19185/MATTERS.201903000032
Nadia Ben Fadhel, L. Signor, C. Petosa, M. Noirclerc-Savoye
The HIV-1 Rev (Regulator of Expression of Virion) protein, an RNA-binding protein essential for viral replication, is imported into the host cell nucleus by human Importin β (Impβ). Rev is phosphorylated in vivo on serine residues by a nuclear kinase. In this study, we introduced glutamate substitution mutations that mimic phosphorylation at serine positions previously identified as potential phosphorylation sites and assessed their impact on the ability of Rev to bind Impβ in thermal shift, gel shift, and fluorescence polarization assays. Phosphomimetic mutations introduced in either the N-terminal tail, helical hairpin domain or C-terminal domain of Rev had a small but reproducible stabilizing effect on the Impβ/Rev complex. Moreover, the mutation of Rev residue Ser56, which localizes to one face of the helical hairpin domain, had a greater stabilizing effect than that of Ser54 located on the opposite face, suggesting that the helical hairpin orients its Ser56-containing face towards Impβ. Taken together, our results suggest that phosphorylation can significantly modulate the ability of Rev to associate with Impβ.
HIV-1 Rev (Regulator of Expression of Virion)蛋白是一种病毒复制所必需的rna结合蛋白，通过human importtin β (Impβ)导入宿主细胞核。Rev在体内通过核激酶在丝氨酸残基上磷酸化。在这项研究中，我们引入了谷氨酸取代突变，模拟了丝氨酸位点的磷酸化，并在热位移、凝胶位移和荧光极化分析中评估了它们对Rev结合Impβ能力的影响。在Rev的n端尾部、螺旋发卡结构域或c端结构域引入的拟磷突变对Impβ/Rev复合物具有较小但可重复的稳定作用。此外，位于螺旋发夹结构域一侧的Rev残基Ser56的突变比位于相反一侧的Ser54的突变具有更大的稳定作用，这表明螺旋发夹结构域的Ser56面朝向Impβ。综上所述，我们的研究结果表明，磷酸化可以显著调节Rev与Impβ结合的能力。
{"title":"Phosphomimetic mutations modulate the ability of HIV-1 Rev to bind human Importin β in vitro","authors":"Nadia Ben Fadhel, L. Signor, C. Petosa, M. Noirclerc-Savoye","doi":"10.19185/MATTERS.201903000032","DOIUrl":"https://doi.org/10.19185/MATTERS.201903000032","url":null,"abstract":"The HIV-1 Rev (Regulator of Expression of Virion) protein, an RNA-binding protein essential for viral replication, is imported into the host cell nucleus by human Importin β (Impβ). Rev is phosphorylated in vivo on serine residues by a nuclear kinase. In this study, we introduced glutamate substitution mutations that mimic phosphorylation at serine positions previously identified as potential phosphorylation sites and assessed their impact on the ability of Rev to bind Impβ in thermal shift, gel shift, and fluorescence polarization assays. Phosphomimetic mutations introduced in either the N-terminal tail, helical hairpin domain or C-terminal domain of Rev had a small but reproducible stabilizing effect on the Impβ/Rev complex. Moreover, the mutation of Rev residue Ser56, which localizes to one face of the helical hairpin domain, had a greater stabilizing effect than that of Ser54 located on the opposite face, suggesting that the helical hairpin orients its Ser56-containing face towards Impβ. Taken together, our results suggest that phosphorylation can significantly modulate the ability of Rev to associate with Impβ.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79993669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-05DOI: 10.19185/MATTERS.201903000031
Ana C Maia-Fernandes, T. P. D. Azevedo, A. Marreiros, I. Palmeirim, R. P. Andrade
Early embryo elongation involves coordinated cellular and tissue behaviors that are readily observable in the chick embryo vertebrate model system. Easily identifiable morphological landmarks are crucial to obtain reliable morphometric data, particularly when assessing tissue elongation over time. The posterior end of the primitive streak marks the caudal end of the chick embryonic tissue. However, the identification of its precise location is ambiguous, especially to the untrained eye. Herein, we assessed if the posterior limit of the area pellucida (pPL), which is readily recognizable due to the optical contrast with the area opaca, is a valid proxy for the caudal limit of the primitive streak. Measurements of total embryo length were performed in multiple images of chick embryos over time using both caudal landmarks. We found that the pPL offered greater precision and a higher degree of inter-user reproducibility, when compared to the end of the primitive streak. Importantly, our work uncovers a quantitative proportionality between embryo length measurements using the end of the primitive streak and the pPL as caudal landmarks. We have thus validated the pPL as a reliable morphological proxy for the end of the primitive streak in chick embryo elongation studies.
{"title":"The posterior limit of the area pellucida (pPL) as a reliable proxy for the end of the primitive streak in chick elongation studies","authors":"Ana C Maia-Fernandes, T. P. D. Azevedo, A. Marreiros, I. Palmeirim, R. P. Andrade","doi":"10.19185/MATTERS.201903000031","DOIUrl":"https://doi.org/10.19185/MATTERS.201903000031","url":null,"abstract":"Early embryo elongation involves coordinated cellular and tissue behaviors that are readily observable in the chick embryo vertebrate model system. Easily identifiable morphological landmarks are crucial to obtain reliable morphometric data, particularly when assessing tissue elongation over time. The posterior end of the primitive streak marks the caudal end of the chick embryonic tissue. However, the identification of its precise location is ambiguous, especially to the untrained eye. Herein, we assessed if the posterior limit of the area pellucida (pPL), which is readily recognizable due to the optical contrast with the area opaca, is a valid proxy for the caudal limit of the primitive streak. Measurements of total embryo length were performed in multiple images of chick embryos over time using both caudal landmarks. We found that the pPL offered greater precision and a higher degree of inter-user reproducibility, when compared to the end of the primitive streak. Importantly, our work uncovers a quantitative proportionality between embryo length measurements using the end of the primitive streak and the pPL as caudal landmarks. We have thus validated the pPL as a reliable morphological proxy for the end of the primitive streak in chick embryo elongation studies.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84800598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-04-05DOI: 10.19185/MATTERS.201903000014
Susana Ponte, Antonio Jacinto Prof., Lara Carvalho
Epithelia are essential tissues in all multicellular organisms to establish a barrier against the external environment. To exert this vital function, epithelial cells need to be tightly connected to each other while at the same time they allow for complex tissue and cell shapes to arise. Occluding Junctions (OJs) have evolved to become epithelia’s gatekeepersthey seal intercellular spaces but also provide selective permeability. Recent studies have also proposed that OJs regulate epithelial morphogenesis and polarity, but themechanisms are still poorly understood. Herewe explored novel functions of OJs by investigating the function of Neurexin-IV (Nrx-IV), a conserved transmembrane protein of the Neurexin/Contactin family localized at invertebrate OJs, using theDrosophila melanogaster larval epithelium as a model system. By knocking down the expression of this protein in a specific subset of epithelial cells and in a time-controlled manner, we show that Nrx-IV is required for proper epithelial tissue organization and survival. This suggests that OJs play a more important role in epithelial morphogenesis than previously anticipated. As Nrx-IV is also present in invertebrate glial OJs and in vertebrate axo-glial junctions this work not only increases our knowledge about epithelia but can also have implications in nervous system biology.
上皮细胞是所有多细胞生物中必不可少的组织，用于建立对抗外部环境的屏障。为了发挥这一重要功能，上皮细胞需要彼此紧密连接，同时它们允许复杂的组织和细胞形状出现。闭塞连接(oj)已经进化成为上皮的守门人，它们封闭细胞间隙，但也提供选择性通透性。最近的研究也提出oj调节上皮的形态发生和极性，但其机制仍然知之甚少。本文以黑腹果蝇幼虫上皮为模型系统，通过研究Neurexin- iv (Nrx-IV)的功能，探索oj的新功能。Nrx-IV是Neurexin/Contactin家族的保守跨膜蛋白，定位于无脊椎动物oj。通过在特定的上皮细胞亚群中以时间控制的方式敲除该蛋白的表达，我们表明Nrx-IV是正常上皮组织和存活所必需的。这表明oj在上皮形态发生中发挥的作用比先前预期的更重要。由于Nrx-IV也存在于无脊椎动物的神经胶质oj和脊椎动物的轴胶质连接中，这项工作不仅增加了我们对上皮细胞的了解，而且还可能对神经系统生物学产生影响。
{"title":"The occluding junction protein Neurexin-IV is required for tissue integrity in the Drosophila wing disc epithelium","authors":"Susana Ponte, Antonio Jacinto Prof., Lara Carvalho","doi":"10.19185/MATTERS.201903000014","DOIUrl":"https://doi.org/10.19185/MATTERS.201903000014","url":null,"abstract":"Epithelia are essential tissues in all multicellular organisms to establish a barrier against the external environment. To exert this vital function, epithelial cells need to be tightly connected to each other while at the same time they allow for complex tissue and cell shapes to arise. Occluding Junctions (OJs) have evolved to become epithelia’s gatekeepersthey seal intercellular spaces but also provide selective permeability. Recent studies have also proposed that OJs regulate epithelial morphogenesis and polarity, but themechanisms are still poorly understood. Herewe explored novel functions of OJs by investigating the function of Neurexin-IV (Nrx-IV), a conserved transmembrane protein of the Neurexin/Contactin family localized at invertebrate OJs, using theDrosophila melanogaster larval epithelium as a model system. By knocking down the expression of this protein in a specific subset of epithelial cells and in a time-controlled manner, we show that Nrx-IV is required for proper epithelial tissue organization and survival. This suggests that OJs play a more important role in epithelial morphogenesis than previously anticipated. As Nrx-IV is also present in invertebrate glial OJs and in vertebrate axo-glial junctions this work not only increases our knowledge about epithelia but can also have implications in nervous system biology.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"86 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84107837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-28DOI: 10.19185/MATTERS.201903000024
S. Ferrara, S. Zambetti, D. Braida, R. Morini, M. Sala, M. Matteoli, E. Menna
Several neuropsychiatric diseases, including autism spectrum disorders (ASD) and intellectual disability (ID) are characterized by synaptic dysfunctions, such as, altered number and shape of dendritic spines, and defective synaptic signalling and plasticity. The actin regulatory protein, Eps8, plays a key role in spine morphogenesis and plasticity since neurons lacking Eps8 show defective spine morphology and density and fail to undergo long term potentiation. Consistently, Eps8 KO mice display increased density of immature spines in CA1 hippocampal region and cognitive defects. Also, lower levels of Eps8 have been detected in the brain of a cohort of ASD patients. Preclinical studies showed that environmental factors, such as mice exposure to environmental enrichment (EE) or neuron exposure to increased extracellular Mg2+, may have a “plasticizing action” resulting in improved cognitive functions and higher cellular plasticity. Here, we tested whether early EE or high Mg2+ exposure may rescue the structural synaptic defects of Eps8 KO mice and neurons. Results of this study indicate that the early EE treatment in mice and elevated extracellular Mg2+ concentration in neurons restore normal dendritic morphology and synaptic plasticity in Eps8 KO mice and neurons. These data suggest that early “plasticizing” interventions can be beneficial on synaptic defects and their efficacy in the treatment of neuro-developmental diseases is worth to be investigated.
{"title":"Exposure to Environmental Factors rescues spine defects of Eps8 KO mice","authors":"S. Ferrara, S. Zambetti, D. Braida, R. Morini, M. Sala, M. Matteoli, E. Menna","doi":"10.19185/MATTERS.201903000024","DOIUrl":"https://doi.org/10.19185/MATTERS.201903000024","url":null,"abstract":"Several neuropsychiatric diseases, including autism spectrum disorders (ASD) and intellectual disability (ID) are characterized by synaptic dysfunctions, such as, altered number and shape of dendritic spines, and defective synaptic signalling and plasticity. The actin regulatory protein, Eps8, plays a key role in spine morphogenesis and plasticity since neurons lacking Eps8 show defective spine morphology and density and fail to undergo long term potentiation. Consistently, Eps8 KO mice display increased density of immature spines in CA1 hippocampal region and cognitive defects. Also, lower levels of Eps8 have been detected in the brain of a cohort of ASD patients. Preclinical studies showed that environmental factors, such as mice exposure to environmental enrichment (EE) or neuron exposure to increased extracellular Mg2+, may have a “plasticizing action” resulting in improved cognitive functions and higher cellular plasticity. Here, we tested whether early EE or high Mg2+ exposure may rescue the structural synaptic defects of Eps8 KO mice and neurons. Results of this study indicate that the early EE treatment in mice and elevated extracellular Mg2+ concentration in neurons restore normal dendritic morphology and synaptic plasticity in Eps8 KO mice and neurons. These data suggest that early “plasticizing” interventions can be beneficial on synaptic defects and their efficacy in the treatment of neuro-developmental diseases is worth to be investigated.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82970819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-03-13DOI: 10.19185/MATTERS.201902000007
Satu-Marja Myllymäki, A. Manninen
Laminin-rich basement membrane (BM) guides epithelial cell polarity, regulates epithelial cell behavior and maintains the integrity of epithelial tissues. αβ1and α6β4-integrins both contribute to laminin adhesion and signaling via the assembly of integrin adhesion complexes that help to orient the apico-basal polarity axis. β4-integrin differs from other integrin subunits due to its large cytoplasmic domain that connects to cellular intermediate filament (IF) networks in specialized adhesions called hemidesmosomes (HD). β4-integrin is only known to form a heterodimer with the α6-subunit. In normal tissues, β4-integrin is expressed in cells that also express the α6-subunit. However, in most cells analyzed, β4-integrin is expressed in large excess over α6-integrin and in some tumor cells, β4-integrin appears to promote tumorigenic signaling despite loss of HDs formation. The fate of free β4-subunit and its potential functions in cells have not been extensively studied. Here, we have studied subcellular localization and potential surface delivery of β4-integrin in the absence of its heterodimer partner α6. We provide evidence that a significant fraction of β4-subunit can reach the cell surface without α6-subunit. We also report that β4 is cleaved at its extracellular domain to produce a membrane-bound proteolytic product with an intact cytoplasmic domain. The processed β4-integrin did not co-precipitate with α6-subunit. Taken together, our data suggest that β4-integrin might have functions that are independent of heterodimer formation.
{"title":"Cell surface expression of integrin β4-subunit in the absence of α6-subunit","authors":"Satu-Marja Myllymäki, A. Manninen","doi":"10.19185/MATTERS.201902000007","DOIUrl":"https://doi.org/10.19185/MATTERS.201902000007","url":null,"abstract":"Laminin-rich basement membrane (BM) guides epithelial cell polarity, regulates epithelial cell behavior and maintains the integrity of epithelial tissues. αβ1and α6β4-integrins both contribute to laminin adhesion and signaling via the assembly of integrin adhesion complexes that help to orient the apico-basal polarity axis. β4-integrin differs from other integrin subunits due to its large cytoplasmic domain that connects to cellular intermediate filament (IF) networks in specialized adhesions called hemidesmosomes (HD). β4-integrin is only known to form a heterodimer with the α6-subunit. In normal tissues, β4-integrin is expressed in cells that also express the α6-subunit. However, in most cells analyzed, β4-integrin is expressed in large excess over α6-integrin and in some tumor cells, β4-integrin appears to promote tumorigenic signaling despite loss of HDs formation. The fate of free β4-subunit and its potential functions in cells have not been extensively studied. Here, we have studied subcellular localization and potential surface delivery of β4-integrin in the absence of its heterodimer partner α6. We provide evidence that a significant fraction of β4-subunit can reach the cell surface without α6-subunit. We also report that β4 is cleaved at its extracellular domain to produce a membrane-bound proteolytic product with an intact cytoplasmic domain. The processed β4-integrin did not co-precipitate with α6-subunit. Taken together, our data suggest that β4-integrin might have functions that are independent of heterodimer formation.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90078175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-08DOI: 10.19185/MATTERS.201812000003
D. F. Russell, Desmon E. Rogers, Lilia L. Neiman
The branching of vertebrate neuronal processes, axons or dendrites, is predominantly binary, where a proximal neuronal process bifurcates into two distal progeny. Here, we illustrate counterexamples where neuronal processes branched into more than 2, up to 6, progeny branches, in one step. These were branch points of myelinated dendrites in the peripheral terminals of ALLn cranial nerve afferents innervating the Lorenziniantype ampullary electroreceptors on the rostrum of paddlefish, Polyodon spathula. We imaged afferent terminals fluorescently (in widefield stacks, with deconvolution) after immunolabling of afferent terminals for neuronal cytoplasmic neurofilament-H (NEFH), myelin markers (MBP, P0), or nodal ion channels (Nav1.x, Kv1.1), or after migration of DiI in dendrite membranes. Branched afferent terminals formed a laminar radial radiation beneath a receptive field, parallel to the skin surface, with two serial stages: (1) Starting at each afferent’s centric first branchpoint, each of a small group of 2–4 (most often 3) afferents branched radially into 2–4 (usually 3) generations of myelinated dendrites, whose internodes were covered by sheaths immunoreactive for antigenic markers of myelin (MBP+/P0+), ending distally at ~15 heminode presumed spike initiation zones. (2) From the latter, bundles of unmyelinated (MBP-/P0-) sensory neuron (NEFH+) processes projected distally to innervate electrosensory neuroepithelia of adjacent ampullary organs. The nonbinary branch points that we imaged were in stage-1, on myelinated dendrites. Branch points always coincided with composite systems of nodes, in which each progeny dendrite started at a narrowed nodal segment expressing voltage gated sodium ion channels at high density. These narrowed nodal segments of multiple progeny branched in parallel from a parent’s blunt distal end. Hence the branch point nodal complexes formed multisite excitable systems, likely strongly coupled due to proximity.
脊椎动物神经突的分支，轴突或树突，主要是二元的，其中一个近端神经元突分岔成两个远端后代。在这里，我们举例说明反例，其中神经元过程分支成2个以上，最多6个，子分支，在一个步骤。这些是支配白鲟喙部lorenzinia型壶腹电感受器的ALLn颅神经传入神经末梢有髓鞘树突的分支点。在神经细胞质神经丝- h (NEFH)、髓磷脂标记物(MBP、P0)或节离子通道(Nav1)免疫后，我们对传入终端进行荧光成像(宽视场堆栈，反卷积)。x, Kv1.1)，或DiI在树突膜中迁移后。分支的传入神经末梢在感受野下形成层状径向辐射，平行于皮肤表面，有两个连续的阶段:(1)从每个传入神经的中心第一个分支点开始，每一个2-4(通常为3)个传入神经末梢径向分支成2-4(通常为3)代有髓鞘树突，其节间被对髓鞘抗原标记物(MBP+/P0+)具有免疫反应的鞘所覆盖，在远端结束于约15个半球处假定的尖峰起始区。(2)从后者，无髓鞘(MBP-/P0-)感觉神经元(NEFH+)突束向远端投射，支配邻近壶腹部器官的电感觉神经上皮。我们成像的非二元分支点处于1期，在有髓鞘的树突上。分支点总是与节点的复合系统重合，其中每个子代枝晶从一个狭窄的节点段开始，表达高密度的电压门控钠离子通道。多个子代的这些狭窄节段从亲本钝的远端平行分枝。因此，分支点节点复合物形成了多位点可激发系统，可能由于邻近而强耦合。
{"title":"Nonbinary branching of myelinated dendrites at nodal networks on afferent terminal arbors in paddlefish electroreceptors","authors":"D. F. Russell, Desmon E. Rogers, Lilia L. Neiman","doi":"10.19185/MATTERS.201812000003","DOIUrl":"https://doi.org/10.19185/MATTERS.201812000003","url":null,"abstract":"The branching of vertebrate neuronal processes, axons or dendrites, is predominantly binary, where a proximal neuronal process bifurcates into two distal progeny. Here, we illustrate counterexamples where neuronal processes branched into more than 2, up to 6, progeny branches, in one step. These were branch points of myelinated dendrites in the peripheral terminals of ALLn cranial nerve afferents innervating the Lorenziniantype ampullary electroreceptors on the rostrum of paddlefish, Polyodon spathula. We imaged afferent terminals fluorescently (in widefield stacks, with deconvolution) after immunolabling of afferent terminals for neuronal cytoplasmic neurofilament-H (NEFH), myelin markers (MBP, P0), or nodal ion channels (Nav1.x, Kv1.1), or after migration of DiI in dendrite membranes. Branched afferent terminals formed a laminar radial radiation beneath a receptive field, parallel to the skin surface, with two serial stages: (1) Starting at each afferent’s centric first branchpoint, each of a small group of 2–4 (most often 3) afferents branched radially into 2–4 (usually 3) generations of myelinated dendrites, whose internodes were covered by sheaths immunoreactive for antigenic markers of myelin (MBP+/P0+), ending distally at ~15 heminode presumed spike initiation zones. (2) From the latter, bundles of unmyelinated (MBP-/P0-) sensory neuron (NEFH+) processes projected distally to innervate electrosensory neuroepithelia of adjacent ampullary organs. The nonbinary branch points that we imaged were in stage-1, on myelinated dendrites. Branch points always coincided with composite systems of nodes, in which each progeny dendrite started at a narrowed nodal segment expressing voltage gated sodium ion channels at high density. These narrowed nodal segments of multiple progeny branched in parallel from a parent’s blunt distal end. Hence the branch point nodal complexes formed multisite excitable systems, likely strongly coupled due to proximity.","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78510872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"De quoi la « guerre contre le terrorisme » est-elle le nom ?","authors":"D. Fonseca","doi":"10.3917/grief.192.0057","DOIUrl":"https://doi.org/10.3917/grief.192.0057","url":null,"abstract":"","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89623330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-13DOI: 10.19185/MATTERS.201811000001
Sarah Bajan, M. Johnston, G. Hutvagner
The Argonaute 2 (Ago2) protein is an essential effector protein in miRNA-mediated mechanisms that regulate gene expression. Ago2 directly binds to the miRNA, forming the RISC. RISC function is critical to controlling key biological processes and when dysregulated can result in disease pathogenesis. Understanding Ago2 protein stability and turnover will further our understanding in how RISC function is regulated. In human cells, we discovered a previously unidentified ~55 kDa protein that is a truncated form of Ago2, that is formed from proteolytic cleavage of the full length Ago2 protein. Further experiments are needed to determine (i) the detailed mechanism that forms halfAgo2 (ii) the cellular or environmental triggers or stresses that initiate halfAgo2 production and (iii) if halfAgo2 has a potentially new role in gene regulation. Introduction miRNAs are endogenous small molecules that are essential regulators of human development. miRNAs function by targeting the post-transcriptional stages of gene expression, via several distinct mechanisms [1]. miRNA regulatory function depends on the miRNA directly binding to an Argonaute (Ago) protein, forming the RNA Induced Silencing Complex (RISC). In this complex the miRNA acts a guide, by binding to a complementary site within mRNA and bringing the RISC, and its associated regulatory proteins, to the target [2] [3]. RISC regulates key biological processes, therefore any disruption to RISC function can have severe consequences, and misregulation of RISC is implicated in the development of disease [4]. It is therefore important that the stability of RISC and accordingly its components, miRNA andAgo, are controlled. There are several knownmechanisms that mediatemiRNA stability and turnover, including homeostatic and feedbackmechanisms that coordinate miRNA levels with Ago levels [5] [6] [7] [8]. However, we have only limited understanding into mechanisms that regulate the turnover of Ago proteins and the RISC complex. There is emerging evidence that Ago function and stability is mediated by a variety of post-translational modifications of the protein, which occurs as a consequence of complex signalling pathways [9] [10] [11] [12] [13]. These modifications can alter protein function, stability, and localisation. Depending on the modification, these changes can be permanent or reversible. Therefore Ago levels are potentially highly dynamic and are responsive to internal and external stimuli. While the 4 human Ago proteins (1–4) display some functional redundancy, Ago2 is the most abundant in commonly used human cell lines [14] and the most studied in miRNA regulation. Objective While analysing the protein expression of full-length (FL), endogenous, Ago2 (~85 kDa) in HeLa cell lysate, we observed that an Ago2-specific monoclonal antibody targeted to the N-terminus of the protein [15], also bound to a previously unidentified protein of approximately 55 kDa. The objective of this study was to investigate thi
Argonaute 2 (Ago2)蛋白是mirna介导的调控基因表达机制中必不可少的效应蛋白。Ago2直接与miRNA结合，形成RISC。RISC功能对控制关键的生物过程至关重要，当失调时可能导致疾病发病。了解Ago2蛋白的稳定性和周转将进一步加深我们对RISC功能如何调控的理解。在人类细胞中，我们发现了一种以前未被识别的~55 kDa蛋白，它是Ago2的截断形式，它是由全长Ago2蛋白的蛋白水解裂解形成的。需要进一步的实验来确定(i)形成halfAgo2的详细机制(ii)启动halfAgo2产生的细胞或环境触发或胁迫，以及(iii) halfAgo2是否在基因调控中具有潜在的新作用。mirna是一种内源性小分子，是人类发育的重要调节因子。mirna通过几种不同的机制靶向基因表达的转录后阶段发挥作用。miRNA的调控功能依赖于miRNA直接与Argonaute (Ago)蛋白结合，形成RNA诱导沉默复合体(RISC)。在这个复合体中，miRNA通过结合mRNA内的互补位点，将RISC及其相关调节蛋白带到目标[2][3]，起到引导作用。RISC调节关键的生物过程，因此任何对RISC功能的破坏都可能产生严重后果，而RISC的失调与疾病的发展有关。因此，控制RISC及其成分miRNA和ago的稳定性非常重要。有几种已知的介导miRNA稳定和转换的机制，包括调节miRNA水平与Ago水平[5][6][7][8]的稳态和反馈机制。然而，我们对Ago蛋白和RISC复合体的周转调节机制了解有限。越来越多的证据表明Ago的功能和稳定性是由蛋白质的多种翻译后修饰介导的，这种修饰是复杂信号通路[9][10][11][12][13]的结果。这些修饰可以改变蛋白质的功能、稳定性和定位。根据修改的不同，这些更改可以是永久的，也可以是可逆的。因此，Ago水平可能是高度动态的，对内部和外部刺激都有反应。虽然4种人类Ago蛋白(1-4)显示出一定的功能冗余，但在常用的人类细胞系[14]中，Ago2是最丰富的，也是在miRNA调控中研究最多的。目的分析HeLa细胞裂解液中全长(FL)内源性Ago2 (~85 kDa)的蛋白表达，发现一种Ago2特异性单克隆抗体靶向[15]蛋白的n端，该抗体也与一种先前未识别的约55 kDa的蛋白结合。本研究的目的是研究这个55kda蛋白，并验证我们的假设，即该蛋白是FL人Ago2的截断形式。Argonaute 2的不稳定产生截断蛋白:halfAgo2 DOI: N/ a Matters (ISSN: 2297-8240) |2 a
{"title":"Destabilisation of Argonaute 2 generates a truncated protein: halfAgo2","authors":"Sarah Bajan, M. Johnston, G. Hutvagner","doi":"10.19185/MATTERS.201811000001","DOIUrl":"https://doi.org/10.19185/MATTERS.201811000001","url":null,"abstract":"The Argonaute 2 (Ago2) protein is an essential effector protein in miRNA-mediated mechanisms that regulate gene expression. Ago2 directly binds to the miRNA, forming the RISC. RISC function is critical to controlling key biological processes and when dysregulated can result in disease pathogenesis. Understanding Ago2 protein stability and turnover will further our understanding in how RISC function is regulated. In human cells, we discovered a previously unidentified ~55 kDa protein that is a truncated form of Ago2, that is formed from proteolytic cleavage of the full length Ago2 protein. Further experiments are needed to determine (i) the detailed mechanism that forms halfAgo2 (ii) the cellular or environmental triggers or stresses that initiate halfAgo2 production and (iii) if halfAgo2 has a potentially new role in gene regulation. Introduction miRNAs are endogenous small molecules that are essential regulators of human development. miRNAs function by targeting the post-transcriptional stages of gene expression, via several distinct mechanisms [1]. miRNA regulatory function depends on the miRNA directly binding to an Argonaute (Ago) protein, forming the RNA Induced Silencing Complex (RISC). In this complex the miRNA acts a guide, by binding to a complementary site within mRNA and bringing the RISC, and its associated regulatory proteins, to the target [2] [3]. RISC regulates key biological processes, therefore any disruption to RISC function can have severe consequences, and misregulation of RISC is implicated in the development of disease [4]. It is therefore important that the stability of RISC and accordingly its components, miRNA andAgo, are controlled. There are several knownmechanisms that mediatemiRNA stability and turnover, including homeostatic and feedbackmechanisms that coordinate miRNA levels with Ago levels [5] [6] [7] [8]. However, we have only limited understanding into mechanisms that regulate the turnover of Ago proteins and the RISC complex. There is emerging evidence that Ago function and stability is mediated by a variety of post-translational modifications of the protein, which occurs as a consequence of complex signalling pathways [9] [10] [11] [12] [13]. These modifications can alter protein function, stability, and localisation. Depending on the modification, these changes can be permanent or reversible. Therefore Ago levels are potentially highly dynamic and are responsive to internal and external stimuli. While the 4 human Ago proteins (1–4) display some functional redundancy, Ago2 is the most abundant in commonly used human cell lines [14] and the most studied in miRNA regulation. Objective While analysing the protein expression of full-length (FL), endogenous, Ago2 (~85 kDa) in HeLa cell lysate, we observed that an Ago2-specific monoclonal antibody targeted to the N-terminus of the protein [15], also bound to a previously unidentified protein of approximately 55 kDa. The objective of this study was to investigate thi","PeriodicalId":90172,"journal":{"name":"Grief matters","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88167427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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