Rapid glycation with D-ribose induces globular amyloid-like aggregations of BSA with high cytotoxicity to SH-SY5Y cells

<p>Abstract</p> <p>Background</p> <p>D-ribose in cells and human serum participates in glycation of proteins resulting in advanced glycation end products (AGEs) that affect cell metabolism and induce cell death. However, the mechanism by which D-ribose-glycated proteins induce cell death is still unclear.</p> <p>Results</p> <p>Here, we incubated D-ribose with bovine serum albumin (BSA) and observed changes in the intensity of fluorescence at 410 nm and 425 nm to monitor the formation of D-ribose-glycated BSA. Comparing glycation of BSA with xylose (a control for furanose), glucose and fructose (controls for pyranose), the rate of glycation with D-ribose was the most rapid. Protein intrinsic fluorescence (335 nm), Nitroblue tetrazolium (NBT) assays and Western blotting with anti-AGEs showed that glycation of BSA incubated with D-ribose occurred faster than for the other reducing sugars. Protein intrinsic fluorescence showed marked conformational changes when BSA was incubated with D-ribose. Importantly, observations with atomic force microscopy showed that D-ribose-glycated BSA appeared in globular polymers. Furthermore, a fluorescent assay with Thioflavin T (ThT) showed a remarkable increase in fluorescence at 485 nm in the presence of D-ribose-glycated BSA. However, ThT fluorescence did not show the same marked increase in the presence of xylose or glucose. This suggests that glycation with D-ribose induced BSA to aggregate into globular amyloid-like deposits. As observed by Hoechst 33258 staining, 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and cell counting kit-8 (CCK-8) assay, lactate dehydrogenase (LDH) activity assay, flow cytometry using Annexin V and Propidium Iodide staining and reactive oxygen species (ROS) measurements, the amyloid-like aggregation of glycated BSA induced apoptosis in the neurotypic cell line SH-SY5Y.</p> <p>Conclusion</p> <p>Glycation with D-ribose induces BSA to misfold rapidly and form globular amyloid-like aggregations which play an important role in cytotoxicity to neural cells.</p

Bioinformatic analysis of the human DHRS4 gene cluster and a proposed mechanism for its transcriptional regulation

<p>Abstract</p> <p>Background</p> <p>The human <it>DHRS4 </it>gene cluster consists of three genes, <it>DHRS4</it>, <it>DHRS4L2 </it>and <it>DHRS4L1</it>. Among them, <it>DHRS4 </it>encodes NADP(H)-dependent retinol dehydrogenase/reductase. In a previous study, we investigated the alternative splicing of <it>DHRS4 </it>and <it>DHRS4L2</it>. <it>DHRS4L1 </it>was added to the gene cluster recently, but little is known about its structure and expression. To reveal the regulatory mechanism of the <it>DHRS4 </it>gene cluster expression, we studied the structure and transcription of <it>DHRS4L1 </it>in the context of the transcriptional behaviors of the human <it>DHRS4 </it>gene cluster. Based on the results of bioinformatics analysis, we propose a possible mechanism for the transcriptional regulation of the human <it>DHRS4 </it>gene cluster.</p> <p>Results</p> <p>The homologous comparison analysis suggests that <it>DHRS4</it>, <it>DHRS4L2 </it>and <it>DHRS4L1 </it>are three homologous genes in human. <it>DHRS4L1 </it>and <it>DHRS4L2 </it>are paralogues of <it>DHRS4</it>, and <it>DHRS4L2 </it>is the most recent member of the <it>DHRS4 </it>gene cluster. In the minus strand of the human <it>DHRS4 </it>gene cluster, a gene transcribed in an antisense direction was found containing a 5' sequence overlapping the region of exon 1 and promoter of <it>DHRS4</it>. By cloning the full length of RNA variants through 5'RACE and 3'RACE, we identified two transcription start sites, within exon <it>a2 </it>and exon 1, of this newly named gene <it>DHRS4L1 </it>using neuroblastoma cell line BE(2)-M17. Analysis of exon composition in the transcripts of <it>DHRS4 </it>gene cluster revealed that exon 1 was absent in all the transcripts initiated from exon <it>a1 </it>of <it>DHRS4L2 </it>and exon <it>a2 </it>of <it>DHRS4L1</it>.</p> <p>Conclusions</p> <p>Alternatively spliced RNA variants are prevalent in the human <it>DHRS4 </it>gene cluster. Based on the analysis of gene transcripts and bioinformatic prediction, we propose here that antisense transcription may be involved in the transcriptional initiation regulation of <it>DHRS4 </it>and in the posttranscriptional splicing of <it>DHRS4L2 </it>and <it>DRHS4L1 </it>for the homologous identity of <it>DHRS4 </it>gene cluster. Beside the alternative transcriptional start sites, the antisense RNA is novel possible factor serving to remove exon 1 from the transcripts initiated from exon <it>a1 </it>and exon <it>a2</it>.</p

Matrilin-2 within a three-dimensional lysine-modified chitosan porous scaffold enhances Schwann cell migration and axonal outgrowth for peripheral nerve regeneration

Background: Matrilin-2 is a key extracellular matrix protein involved in peripheral nerve regeneration. We sought to develop a biomimetic scaffold to enhance peripheral nerve regeneration by incorporating matrilin-2 within a chitosan-derived porous scaffold. We hypothesized that the use of such a novel biomaterial delivers microenvironmental cues to facilitate Schwann cell (SC) migration and enhance axonal outgrowth during peripheral nerve regeneration.Materials and Methods: The effect of matrilin-2 on SC migration was evaluated with agarose drop migration assay on matrilin-2 coated dishes. SC adhesion was determined with SCs cultured atop tissue culture dishes coated with matrilin-2. Various formulations of chitosan vs matrilin-2 in scaffold constructs were examined with scanning electron microscopy. The effect of the matrilin-2/chitosan scaffold on SC migration in the collagen conduits was determined by capillary migration assays. Neuronal adhesion and axonal outgrowth were evaluated with three-dimensional (3D) organotypic assay of dorsal root ganglions (DRG). DRG axonal outgrowth within the scaffolds was determined by immunofluorescence staining of neurofilaments.Results: Matrilin-2 induced SC migration and enhanced its adhesion. A formulation of 2% chitosan with matrilin-2 demonstrated an optimal 3D porous architecture for SC interaction. Matrilin-2/chitosan scaffold enabled SCs to migrate against gravity within conduits. Chemical modification of chitosan with lysine (K-chitosan) further improved DRG adhesion and axonal outgrowth than the matrilin-2/chitosan scaffold without lysine modification.Conclusion: We developed a matrilin-2/K-chitosan scaffold to mimic extracellular matrix cues and provide a porous matrix to enhance peripheral nerve regeneration. Taking advantage of matrilin-2’s capability to stimulate SC migration and adhesion, we formulated a porous matrilin-2/chitosan scaffold to support axongal outgrowth. Chemical modification of chitosan with lysine further improved matrilin-2 bioactivity in the 3D scaffold. The 3D porous matrilin-2/K-chitosan scaffolds have high potential for enhancing nerve repair by stimulating SC migration, neuronal adhesion, and axonal outgrowth

High Genetic Diversity and Low Differentiation of Michelia coriacea (Magnoliaceae), a Critically Endangered Endemic in Southeast Yunnan, China

Michelia coriacea, a critically endangered tree, has a restricted and fragmented distribution in Southeast Yunnan Province, China. The genetic diversity, genetic structure and gene flow in the three extant populations of this species were detected by 10 inter-simple sequence repeat (ISSR) markers and 11 simple sequence repeat (SSR) markers. Examination of genetic diversity revealed that the species maintained a relatively high level of genetic diversity at the species level (percentage of polymorphic bands) PPB = 96.36% from ISSRs; PPL (percentage of polymorphic loci) = 95.56% from SSRs, despite several fragmental populations. Low levels of genetic differentiation among the populations of M. coriacea were detected by Nei’s Gst = 0.187 for ISSR and Wright’s Fst = 0.090 for SSR markers, which is further confirmed by Bayesian model-based STRUCTURE and PCoA analysis that could not reveal a clear separation between populations, although YKP was differentiated to other two populations by ISSR markers. Meanwhile, AMOVA analysis also indicated that 22.84% and 13.90% of genetic variation existed among populations for ISSRs and SSRs, respectively. The high level of genetic diversity, low genetic differentiation, and the population, structure imply that the fragmented habitat and the isolated population of M. coriacea may be due to recent over-exploitation. Conservation and management of M. coriacea should concentrate on maintaining the high level of genetic variability through both in and ex-situ conservation actions

Strain mediated phase crossover in Ruddlesden Popper nickelates

Recent progress on the signatures of pressure-induced high temperature superconductivity in Ruddlesden Popper (RP) nickelates (Lan+1NinO3n+1) has attracted growing interest in both theoretical calculations and experimental efforts. The fabrication of high-quality single crystalline RP nickelate thin films is critical for possible reducing the superconducting transition pressure and advancing applications in microelectronics in the future. In this study, we report the observations of an active phase transition in RP nickelate films induced by misfit strain. We found that RP nickelate films favor the perovskite structure (n = infinite) under tensile strains, while compressive strains stabilize the La3Ni2O7 (n = 2) phase. The selection of distinct phases is governed by the strain dependent formation energy and electronic configuration. In compressively strained La3Ni2O7, we experimentally determined splitting energy is ~0.2 eV and electrons prefer to occupy in-plane orbitals. First principles calculations unveil a robust coupling between strain effects and the valence state of Ni ions in RP nickelates, suggesting a dual driving force for the inevitable phase co-existence transition in RP nickelates. Our work underscores the sensitivity of RP nickelate formation to epitaxial strain, presenting a significant challenge in fabricating pure-phase RP nickelate films. Therefore, special attention to stacking defects and grain boundaries between different RP phases is essential when discussing the pressure-induced superconductivity in RP nickelates.Comment: 29 pages, 5 figures, one supplementary material

Molecular phylogeny and macroevolution of Chaitophorinae aphids (Insecta: Hemiptera: Aphididae)

Chaitophorinae is a predominantly Northern Hemisphere aphid subfamily characterized by numerous setae on the body. Two constituent tribes are associated with different host plants, with Chaitophorini feeding on deciduous trees and shrubs and Siphini colonizing grasses. Based on data from multiple genes (COI, COII, Cytb and EF-1α), geographical distribution and host association, this study investigated the phylogeny and macroevolution of Chaitophorinae using phylogenetic reconstruction, molecular dating, model-based ancestral area and character estimations and diversification rate calculation. Our results support the monophyly of Chaitophorinae and two tribes, indicate that Sipha and the two largest genera Chaitophorus and Periphyllus are not monophyletic, and suggest a need for a change in the taxonomic status of Lambersaphis, which was nested within Chaitophorus in the phylogenetic tree. We recovered an origin of Chaitophorinae on Acer plants from eastern Asia during the Late Cretaceous to early Palaeocene, followed by multiple dispersals into other areas that were responsible for its contemporary distribution. The origins of Siphini and Chaitophorus + Lambersaphis coincided with colonizations of novel host plants. An increase in diversification rate occurred within Chaitophorus in the Miocene and was associated with range expansion and switching onto new host plants, highlighting the roles of dispersal and host shift in aphid diversification

Carbonized Cow Dung as a High Performance and Low Cost Anode Material for Bioelectrochemical Systems

We develop a high-performance anode formed from carbonized cow dung for bioelectrochemical systems. Thermal gravimetric analysis showed that the CD carbonization process started at 300°C and ended at approximately 550°C; the weight was reduced by 51%. After a heat-treatment at 800°C for 2 h, the treated CD featured a good conductivity and a high specific surface area. The maximum current density of 11.74 ± 0.41 A m-2 was achieved by CD anode (heated at 800°C), which remained relatively stable from more than 10 days. This study shows that a valuable anode material can be produced through conversion of CD by high-temperature carbonization. This approach provides a new way to alleviate environmental problems associated with CD

Aberrant GlyRS-HDAC6 interaction linked to axonal transport deficits in Charcot-Marie-Tooth neuropathy.

Dominant mutations in glycyl-tRNA synthetase (GlyRS) cause a subtype of Charcot-Marie-Tooth neuropathy (CMT2D). Although previous studies have shown that GlyRS mutants aberrantly interact with Nrp1, giving insight into the disease\u27s specific effects on motor neurons, these cannot explain length-dependent axonal degeneration. Here, we report that GlyRS mutants interact aberrantly with HDAC6 and stimulate its deacetylase activity on α-tubulin. A decrease in α-tubulin acetylation and deficits in axonal transport are observed in mice peripheral nerves prior to disease onset. An HDAC6 inhibitor used to restore α-tubulin acetylation rescues axonal transport deficits and improves motor functions of CMT2D mice. These results link the aberrant GlyRS-HDAC6 interaction to CMT2D pathology and suggest HDAC6 as an effective therapeutic target. Moreover, the HDAC6 interaction differs from Nrp1 interaction among GlyRS mutants and correlates with divergent clinical presentations, indicating the existence of multiple and different mechanisms in CMT2D. Nat Commun 2018 Mar 8; 9(1):1007