Luman/CREB3 is a novel retrograde regulator of sensory neuron regeneration: mechanism of action

Luman (CREB3, LZIP) is a basic leucine zipper transcription factor involved in regulation of the unfolded protein response (UPR), dendritic cell maturation, and cell migration. But despite reported expression in primary sensory neurons, little is known about its role in the nervous system. Luman mRNA from rat sensory neurons was amplified and its coding sequence was determined. The rat Luman cDNA contains a full-length open reading frame encoding 387 amino acids, and the recombinant protein generated from this clone activated transcription from UPR elements. Quantitative RT-PCR revealed rat Luman transcripts in a variety of rat tissues with the highest levels in nervous system tissue. In situ hybridization confirmed the findings and demonstrated that the Luman mRNA hybridization signal localizes to neurons and satellite glial cells in dorsal root ganglia (DRG), the cytoplasm of hepatocytes in liver, and the hippocampal pyramidal cell layers in CA1 and CA3 and the granular cell layer of the dentate gyrus. Luman protein localizes with axonal endoplasmic reticulum (ER) components along the axon length within the sciatic nerve and is activated by sciatic nerve injury. Adult sensory axons also contain Luman mRNA which is translated within the axon and transported to the cell body via the importin-mediated retrograde transport system in response to nerve injury. Further, creation of an N-terminal, C-terminal dual fluorescence-tagged Luman adenoviral construct allowed visualization of the cleavage and retrograde translocation of the N-terminal portion of Luman to the nucleus in real time in vivo and in vitro. Neuronal or subcellular axonal knockdown of Luman significantly impaired the intrinsic ability of injury-conditioned, but not naïve, sensory neurons to extend the regeneration-associated elongating form of neurites. Sciatic nerve crush injury also induced activation of the UPR in axotomized DRGs, including genes linked to cholesterol biosynthesis. Knockdown of Luman decreased the activation of UPR and cholesterol biosynthesis, and axotomy-inducted increases in neurite outgrowth, which could be largely rescued with either mild UPR inducer treatment or cholesterol supplementation. Together these findings provide novel insights linking remote injury-associated axonal ER responses to the regenerative growth capacity of adult sensory neurons via axonal activation and synthesis of Luman and reveal a role for the UPR in regulation of axotomy-induced neurite outgrowth that is critically dependent on Luman

An iterative initial-points refinement algorithm for categorical data clustering

The original k-means clustering algorithm is designed to work primarily on numeric data sets. This prohibits the algorithm from being directly applied to categorical data clustering in many data mining applications. The k-modes algorithm [Z. Huang, Clustering large data sets with mixed numeric and categorical value, in: Proceedings of the First Pacific Asia Knowledge Discovery and Data Mining Conference. World Scientific, Singapore, 1997, pp. 21–34] extended the k-means paradigm to cluster categorical data by using a frequency-based method to update the cluster modes versus the k-means fashion of minimizing a numerically valued cost. However, as is the case with most data clustering algorithms, the algorithm requires a pre-setting or random selection of initial points (modes) of the clusters. The differences on the initial points often lead to considerable distinct cluster results. In this paper we present an experimental study on applying Bradley and Fayyad\u27s iterative initial-point refinement algorithm to the k-modes clustering to improve the accurate and repetitiveness of the clustering results [cf. P. Bradley, U. Fayyad, Refining initial points for k-mean clustering, in: Proceedings of the 15th International Conference on Machine Learning, Morgan Kaufmann, Los Altos, CA, 1998]. Experiments show that the k-modes clustering algorithm using refined initial points leads to higher precision results much more reliably than the random selection method without refinement, thus making the refinement process applicable to many data mining applications with categorical data

Plant diversity increases N removal in constructed wetlands when multiple rather than single N processes are considered

Biodiversity has a close relationship with ecosystem functioning. For most biodiversity–ecosystem‐functioning studies, biodiversity has been linked to a single indicator variable of ecosystem functioning. However, there are generally multiple ecosystem processes contributing to ecosystem functioning and they differ in their dependence on biodiversity. Thus, the relationship between biodiversity and ecosystem functioning can be stronger when multiple rather than single ecosystem processes are considered. Using both mass‐balance and stable‐isotope approaches, we explored the effects of plant diversity on nitrogen (N) removal sustained by multiple N‐cycling processes in experimental microcosms simulating constructed wetlands, an ecosystem treating wastewater with high N loading. Four species were used to assemble different plant communities, ranging in richness from one to four species. The removal of N, indicated by low levels of total inorganic N concentration (TIN) present in the effluent, was considered as an integrated measure of ecosystem functioning, combining three constituent N‐cycling processes: plant uptake, denitrification, and substrate adsorption. Our results showed that (1) species richness had a positive effect on N removal, in particular, the four‐species mixture reduced effluent TIN to a lower level than any monoculture; however, polycultures (two‐, three‐, and four‐species mixtures) did not outperform the most efficient monoculture when each of the three constituent N‐cycling processes was considered by itself; (2) species identity had significant impacts on single processes. Communities with the species Coix lacryma‐jobi showed the greatest capacity for N uptake and communities with Phragmites australis had the highest denitrification rates; (3) isotope fractionation in the rhizosphere of Coix lacryma‐jobi was primarily due to microbial denitrification while multistep isotope fractionation was detected for Phragmites australis and Acorus calamus (indicating recycling of N), suggesting that species differed in the way they transformed N; (4) the enhanced N removal at high diversity may be due to mutualistic interactions among species belonging to different functional types. Our findings demonstrated that although plant species richness had negligible effects on individual N‐cycling processes, it enhanced the overall ecosystem functioning (N removal) when these processes were considered collectively. Our study thus contributes to improve the treatment efficiency of constructed wetlands through proper vegetation management

Selective Detection of Fe3+ by Nitrogen–Sulfur-Doped Carbon Dots Using Thiourea and Citric Acid

The quantum yield and fluorescence properties of carbon dots are key issues for environmental detection. In this study, nitrogen–sulfur-doped carbon dots (N,S-CDs) were prepared hydrothermally by adding thiourea to provide the N source. By adjusting the ratio of citric acid (CA) to thiourea (N,S) and adding anhydrous ethanol, blue fluorescent doped carbon dots with a quantum yield of up to 53.80% were obtained. The particle morphology and crystalline organization of the N,S-CDs were analyzed using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Fourier transform infrared (FTIR) spectroscopy was used to illuminate distinct functional units through the recording of typical vibration bands. The luminescence properties of the N,S-CDs were investigated using ultraviolet–visible (UV-vis) absorption spectroscopy and steady-state fluorescence spectroscopy (PL). In addition, the fluorescence stability of the N,S-CDs was studied in detail. The results showed that the functional groups of the N,S-CDs chelate Fe3+ ions to quench the fluorescence of carbon dots. This shows that the N,S-CDs exhibit high selectivity for Fe3+ ions. With the addition of Fe3+ in the concentration of 0–100 µM, the fluorescence intensity of the N,S-CDs exhibited distinct and linear dependence upon the Fe3+ concentration (R2 = 0.9965), and the detection limit (D = 3ơ/m) was measured as 0.2 µM. The excellent optical properties and Fe3+ selectivity of the N,S-CDs provide a huge boost for application in the field of environmental monitoring

First-principles calculations of diamond/copper (silver, titanium carbide) interface properties

The structure, electrical structure, and heat transmission of diamond/copper, diamond/silver, and diamond/titanium carbide surfaces have been investigated using first-principles calculations. The results show that the diamond/titanium carbide interfacial structure is the most stable, with the shortest interfacial distance (1.990 Å), the greatest interfacial adhesion effort (5.578 J/m2), and the best bond strength. The results of the electronic density of states, mulliken population analysis ,charge density difference, and radial distribution function indicate the presence of more charge transfer and stronger bonding in diamond/titanium carbide. According to the results of the phonon density calculation, the interfacial thermal resistance of diamond/titanium carbide is low

Schwann cell promotes macrophage recruitment through IL-17B/IL-17RB pathway in injured peripheral nerves

Summary: Macrophage recruitment to the injured nerve initiates a cascade of events, including myelin debris clearance and nerve trophic factor secretion, which contribute to proper nerve tissue repair. However, the mechanism of macrophage recruitment is still unclear. Here, by comparing wild-type with Mlkl−/− and Sarm1−/− mice, two mouse strains with impaired myelin debris clearance after peripheral nerve injury, we identify interleukin-17B (IL-17B) as a key regulator of macrophage recruitment. Schwann-cell-secreted IL-17B acts in an autocrine manner and binds to IL-17 receptor B to promote macrophage recruitment, and global or Schwann-cell-specific IL-17B deletion reduces macrophage infiltration, myelin clearance, and axon regeneration. We also show that the IL-17B signaling pathway is defective in the injured central nerves. These results reveal an important role for Schwann cell autocrine signaling during Wallerian degeneration and point to potential mechanistic targets for accelerating myelin clearance and improving demyelinating disease

Screening of cadmium resistant bacteria and their growth promotion of Sorghum bicolor (L.) Moench under cadmium stress

Heavy metal pollution of agricultural soils, especially from cadmium (Cd) contaminationcaused serious problems in both food security and economy. Sorghum bicolor (L.) showed a great potential in phytoremediation of Cd contamination due to its fast growth, high yield and easy harvesting. However, the growth of S. bicolor plants tends to be inhibited under Cd exposure, which limited its application for Cd remediation. Plant growth-promoting rhizobacteria may enhance the Cd resistance of S. bicolor and thus improve its Cd removal efficiency. In this study, three Cd-resistant bacteria were screened based on Cd and acid tolerance and identified as Bacillus velezensis QZG6, Enterobacter cloacae QZS3 and Bacillus cereus QZS8, by 16S rRNA sequencing. Inoculation of hydroponic plants with strains QZG6, QZS3 or QZS8 significantly promoted the biomass of sorghum plants by 31.52%, 50.20% and 26.93%, respectively, compared with those of uninoculated plants under Cd exposure. The activity of SOD, POD and MDA content in Cd-stressed S. bicolor plants were reduced of 65.74%, 31.52%, and 80.91%, respectively, when inoculated with the strains QZS3. For pot experiment, strains QZG6, QZS3 and QZS8 significantly promoted the biomass of sorghum plants by 47.30%, 19.27% and 58.47%, compared with those of uninoculated plants under Cd exposure. The activity of SOD, POD and MDA content in Cd-stressed S. bicolor plants were reduced of 67.20%, 22.40%, and 40.65%, respectively, when inoculated with the strains QZS3. All these three strains significantly increased the Cd removal efficiency of the plants by 42.16% (QZG6), 18.76% (QZS3) and 21.06% (QZS8). To investigate the bacterial characteristics associated with growth promotion of S. bicolor plants, the ability on nitrogen fixation, phosphorus solubilization, siderophores production, and phytohormones production were determined. All the strains were able to fix nitrogen. Phosphorus release was observed for strains QZG6 (inorganic or organic phosphorus) and QZS3 (inorganic phosphorus). Both QZG6 and QZS8 were able to produce siderophores, while only QZG6 was positive for ACC deaminase. All the strains produced IAA, SA and GA. These results indicated that the three strains promoted the plant growth under Cd stress, probably through Cd detoxification by siderophores, as well as through growth regulation by N/P nutrient supply and phytohormone. The present study showed a great potential of the three Cd-resistant strains combined with S. bicolor plants in the remediation of Cd-polluted soils, which may provide a new insight into combining the advantages of microbes and plants to improve the remediation of Cd-contaminated soils