scholarly journals Cytoskeletal assembly in axonal outgrowth and regeneration analyzed on the nanoscale

2021 ◽  
Author(s):  
Max Hofmann ◽  
Lucas Biller ◽  
Uwe Michel ◽  
Mathias Bähr ◽  
Jan Christoph Koch
Keyword(s):  
Periodic Structure ◽  
Growth Cone ◽  
Cortical Neurons ◽  
Structure And Function ◽  
Stimulated Emission ◽  
Axonal Outgrowth ◽  
Rat Cortical Neurons ◽  
Temporal And Spatial ◽  
And Function ◽  
Microfluidic Chambers

The axonal cytoskeleton is organized in a highly periodic structure, the membrane-associated periodic skeleton (MPS), which is essential to maintain the structure and function of the axon. Here, we use stimulated emission depletion microscopy (STED) of primary rat cortical neurons in microfluidic chambers to analyze the temporal and spatial sequence of MPS formation at the distal end of growing axons and during regeneration after axotomy. We demonstrate that the MPS does not extend continuously into the growing axon but develops from patches of periodic β-spectrin II arrangements that grow and coalesce into a continuous scaffold. We estimate that the underlying sequence of nucleation, elongation, and subsequent coalescence of periodic β-spectrin II patches takes around 15 hours. Strikingly, we find that development of the MPS occurs faster in regenerating axons after axotomy and note marked differences in the morphology of the growth cone and adjacent axonal regions between regenerating and unlesioned axons. Moreover, we find that inhibition of the spectrin-cleaving enzyme calpain accelerates MPS formation in regenerating axons and increases the number of regenerating axons after axotomy. Taken together, we provide here a detailed nanoscale analysis of MPS development in growing axons.

scholarly journals The Relationship between the Community Structure and Function of Bacterioplankton and the Environmental Response in Qingcaosha Reservoir

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3155
Author(s):  
Shumin Liu ◽  
Fengbin Zhao ◽  
Xin Fang
Keyword(s):  
Water Quality ◽  
Community Structure ◽  
High Throughput Sequencing ◽  
Scientific Basis ◽  
Vital Role ◽  
Structure And Function ◽  
Environmental Response ◽  
Temporal And Spatial ◽  
Density And Biomass ◽  
And Function

Phytoplankton and bacterioplankton play a vital role in the structure and function of aquatic ecosystems, and their activity is closely linked to water eutrophication. However, few researchers have considered the temporal and spatial succession of phytoplankton and bacterioplankton, and their responses to environmental factors. The temporal and spatial succession of bacterioplankton and their ecological interaction with phytoplankton and water quality were analyzed using 16S rDNA high-throughput sequencing for their identification, and the functions of bacterioplankton were predicted. The results showed that the dominant classes of bacterioplankton in the Qingcaosha Reservoir were Gammaproteobacteria, Alphaproteobacteria, Actinomycetes, Acidimicrobiia, and Cyanobacteria. In addition, the Shannon diversity indexes were compared, and the results showed significant temporal differences based on monthly averaged value, although no significant spatial difference. The community structure was found to be mainly influenced by phytoplankton density and biomass, dissolved oxygen, and electrical conductivity. The presence of Pseudomonas and Legionella was positively correlated with that of Pseudanabaena sp., and Sphingomonas and Paragonimus with Melosira granulata. On the contrary, the presence of Planctomycetes was negatively correlated with Melosira granulata, as was Deinococcus-Thermus with Cyclotella sp. The relative abundance of denitrifying bacteria decreased from April to December, while the abundance of nitrogen-fixing bacteria increased. This study provides a scientific basis for understanding the ecological interactions between bacteria, algae, and water quality in reservoir ecosystems.

scholarly journals Axonal mRNA in human embryonic stem cell derived neurons

2016 ◽  
Author(s):  
Rebecca L. Bigler ◽  
Joyce W. Kamande ◽  
Raluca Dumitru ◽  
Mark Niedringhaus ◽  
Anne Marion Taylor
Keyword(s):  
Single Molecule ◽  
Cortical Neurons ◽  
Embryonic Stem ◽  
Mrna Translation ◽  
Model Organisms ◽  
Functional Roles ◽  
Rna Fish ◽  
Rat Cortical Neurons ◽  
Neuronal Types ◽  
Microfluidic Chambers

The identification of axonal mRNAs in model organisms has led to the discovery of multiple proteins synthesized within axons for functional roles such as axon guidance and injury response. The extent to which protein synthesis within the axon is conserved in humans is unknown. Here we used axon-isolating microfluidic chambers to characterize the axonal transcriptome of human embryonic stem cells (hESC-neurons) differentiated using a protocol for glutamatergic neurons. Using gene expression analysis, we identified mRNAs proportionally enriched in axons, representing a functionally unique local transcriptome as compared to the human neuronal transcriptome inclusive of somata and dendrites. Further, we found that the most abundant mRNAs within hESC-neuron axons were functionally similar to the axonal transcriptome of rat cortical neurons. We confirmed the presence of two well characterized axonal mRNAs in model organisms, β-actin and GAP43, within hESC-neuron axons using multiplexed single molecule RNA-FISH. Additionally, we report the novel finding that oxytocin mRNA localized to these human axons and confirmed its localization using RNA-FISH. This new evaluation of mRNA within human axons provides an important resource for studying local mRNA translation and has the potential to reveal both conserved and unique axonal mechanisms across species and neuronal types.

scholarly journals Neuron-Derived Extracellular Vesicles Modulate Microglia Activation and Function

Biology ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 948
Author(s):  
Hui Peng ◽  
Brock T. Harvey ◽  
Christopher I. Richards ◽  
Kimberly Nixon
Keyword(s):  
Extracellular Vesicles ◽  
Cortical Neurons ◽  
Molecular Mechanisms ◽  
Proinflammatory Response ◽  
Tnf Α ◽  
Rat Cortical Neurons ◽  
The Central Nervous System ◽  
And Function ◽  
And Control ◽  
Brain Homeostasis

Microglia act as the immune cells of the central nervous system (CNS). They play an important role in maintaining brain homeostasis but also in mediating neuroimmune responses to insult. The interactions between neurons and microglia represent a key process for neuroimmune regulation and subsequent effects on CNS integrity. However, the molecular mechanisms of neuron-glia communication in regulating microglia function are not fully understood. One recently described means of this intercellular communication is via nano-sized extracellular vesicles (EVs) that transfer a large diversity of molecules between neurons and microglia, such as proteins, lipids, and nucleic acids. To determine the effects of neuron-derived EVs (NDEVs) on microglia, NDEVs were isolated from the culture supernatant of rat cortical neurons. When NDEVs were added to primary cultured rat microglia, we found significantly improved microglia viability via inhibition of apoptosis. Additionally, application of NDEVs to cultured microglia also inhibited the expression of activation surface markers on microglia. Furthermore, NDEVs reduced the LPS-induced proinflammatory response in microglia according to reduced gene expression of proinflammatory cytokines (TNF-α, IL-6, MCP-1) and iNOS, but increased expression of the anti-inflammatory cytokine, IL-10. These findings support that neurons critically regulate microglia activity and control inflammation via EV-mediated neuron–glia communication. (Supported by R21AA025563 and R01AA025591).

scholarly journals The Three-Dimensional Culture System with Matrigel and Neurotrophic Factors Preserves the Structure and Function of Spiral Ganglion NeuronIn Vitro

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Gaoying Sun ◽  
Wenwen Liu ◽  
Zhaomin Fan ◽  
Daogong Zhang ◽  
Yuechen Han ◽  
...  
Keyword(s):  
Growth Cone ◽  
Neurotrophic Factors ◽  
Culture System ◽  
Spiral Ganglion ◽  
Three Dimensional ◽  
3D Culture ◽  
Explant Culture ◽  
Structure And Function ◽  
3D Culture System ◽  
And Function

Whole organ culture of the spiral ganglion region is a resourceful model system facilitating manipulation and analysis of live sprial ganglion neurons (SGNs). Three-dimensional (3D) cultures have been demonstrated to have many biomedical applications, but the effect of 3D culture in maintaining the SGNs structure and function in explant culture remains uninvestigated. In this study, we used the matrigel to encapsulate the spiral ganglion region isolated from neonatal mice. First, we optimized the matrigel concentration for the 3D culture system and found the 3D culture system protected the SGNs against apoptosis, preserved the structure of spiral ganglion region, and promoted the sprouting and outgrowth of SGNs neurites. Next, we found the 3D culture system promoted growth cone growth as evidenced by a higher average number and a longer average length of filopodia and a larger growth cone area. 3D culture system also significantly elevated the synapse density of SGNs. Last, we found that the 3D culture system combined with neurotrophic factors had accumulated effects in promoting the neurites outgrowth compared with 3D culture or NFs treatment only groups. Together, we conclude that the 3D culture system preserves the structure and function of SGN in explant culture.

Spartina alterniflora: Potential Bio-Energy Source for Biofuel Production in China

2011 ◽  
Vol 142 ◽  
pp. 247-251
Author(s):  
Rui Li Li ◽  
Guo Yu Qiu
Keyword(s):  
Energy Source ◽  
Spartina Alterniflora ◽  
Photosynthetic Efficiency ◽  
Spatial Scales ◽  
Sewage Treatment ◽  
Structure And Function ◽  
Biofuel Production ◽  
High Productivity ◽  
Temporal And Spatial ◽  
And Function

Spartina alternifloracan be widely used for fodder, sewage treatment and as a substantial source of bioactive material. As an invader, it strongly disturbs the structure and function of native ecosystem in China. However, it is also a promising bio-energy source. We analyzed the potential ofS. alternifloraas a bio-energy source, including the superiority at both temporal and spatial scales, advantages in high photosynthetic efficiency and high productivity. Meanwhile, its exploitation for biofuel production was introduced.

Mitochondrial transport in processes of cortical neurons is independent of intracellular calcium

2006 ◽  
Vol 291 (6) ◽  
pp. C1193-C1197 ◽  
Author(s):  
Luis Beltran-Parrazal ◽  
Héctor E. López-Valdés ◽  
K. C. Brennan ◽  
Mauricio Díaz-Muñoz ◽  
Jean de Vellis ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Action Potentials ◽  
Synaptic Activity ◽  
Action Potential Firing ◽  
Mitochondrial Movement ◽  
Neuronal Processes ◽  
Potential Firing ◽  
Intracellular Ca ◽  
Rat Cortical Neurons ◽  
And Function

Mitochondria show extensive movement along neuronal processes, but the mechanisms and function of this movement are not clearly understood. We have used high-resolution confocal microscopy to simultaneously monitor movement of mitochondria and changes in intracellular [Ca2+] ([Ca2+]i) in rat cortical neurons. A significant percentage (27%) of the total mitochondria in cortical neuronal processes showed movement over distances of >2 μM. The average velocity was 0.52 μm/s. The velocity, direction, and pattern of mitochondrial movement were not affected by transient increases in [Ca2+]i associated with spontaneous firing of action potentials. Stimulation of Ca2+ transients with forskolin (10 μM) or bicuculline (10 μM), or sustained elevations of [Ca2+]i evoked by glutamate (10 μM) also had no effect on mitochondrial transit. Neither removal of extracellular Ca2+, depletion of intracellular Ca2+ stores with thapsigargin, or inhibition of synaptic activity with TTX (1 μM) or a cocktail of CNQX (10 μM) and MK801 (10 μM) affected mitochondrial movement. These results indicate that movement of mitochondria along processes is a fundamental activity in neurons that occurs independently of physiological changes in [Ca2+]i associated with action potential firing, synaptic activity, or release of Ca2+ from intracellular stores.

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