川芎嗪对Aβ25-35诱导体外大鼠海马神经元细胞凋亡的影响

本文通过Aβ25-35诱导体外原代培养的SD乳大鼠海马神经元,建立Aβ毒性损伤细胞模型,结合AnnexinV-FITC/PI荧光双染法流式细胞术、MTT比色法、实时荧光定量PCR及Western blot方法检测川芎嗪(tetrameth-ylpyrazine,TMP)对原代培养的海马神经元细胞活性、早期凋亡率和Bax、Bcl-2基因表达的影响。结果显示川芎嗪高、中剂量可明显增强细胞活性,增加神经元细胞的存活率(P<0.01),可显著抑制海马神经元细胞早期凋亡(P<0.01),抑制凋亡蛋白Bax的表达(P<0.01),增强抗凋亡蛋白bcl-2的表达(P<0.01)。川芎嗪可通过调节Bax/Bcl-2平衡抵抗Aβ25-35诱导的海马神经元凋亡,降低Aβ的神经元毒性,对海马神经元损伤有明显的保护作用。     

Increasing βB1-crystallin sensitivity to proteolysis caused by the congenital cataract-microcornea syndrome mutation S129R

Congenital hereditary cataract, which is mainly caused by the deposition of crystallins in light-scattering particles, is one of the leading causes of newborn blindness in human beings. Recently, an autosomal dominant congenital cataract-microcornea syndrome in a Chinese family has been associated with the S129R mutation in βB1-crystallin. To investigate the underlying molecular mechanism, we examined the effect of the mutation on βB1-crystallin structure and thermal stability. Biophysical experiments indicated that the mutation impaired the oligomerization of βB1-crystallin and shifted the dimer–monomer equilibrium to monomer. Molecular dynamic simulations revealed that the mutation altered the hydrogen-bonding network and hydrophobic interactions in the subunit interface of the dimeric protein, which resulted in the opening of the tightly associated interacting sites to allow the infiltration of the solvent molecules into the interface. Despite the disruption of βB1-crystallin assembly, the thermal stability of βB1-crystallin was increased by the mutation accompanied by the reduction of thermal aggregation at high temperatures. Further analysis indicated that the mutation significantly increased the sensitivity of βB1-crystallin to trypsin hydrolysis. The digested fragments of the mutant were prone to aggregate and unable to protect βA3-crystallin against aggregation. These results indicated that the thermal stability-beneficial mutation S129R in βB1-crystallin provided an excellent model for discovering molecular mechanisms apart from solubility and stability. Our results also highlighted that the increased sensitivity of mutated crystallins towards proteases might play a crucial role in the pathogenesis of congenital hereditary cataract and associated syndrome.     

Knockdown of OsHox33, a member of the class III homeodomain-leucine zipper gene family, accelerates leaf senescence in rice

The class III homeodomain-leucine zipper (HD-Zip III) gene family plays important roles in plant growth and development, including regulation of apical embryo patterning, embryonic shoot meristem formation, leaf polarity, vascular development, and meristem function, with a particularly crucial function in leaf development. Although HD-Zip III members are highly conserved in land plants, previous studies, such as genetic analyses based on multiple mutants in Arabidopsis and other plants, suggest that various HD-Zip III family genes have evolved with distinct functions and pleiotropic effects on plant growth and development. In this study, we analyzed a HD-Zip III member, OsHox33, and demonstrated that it plays an important role in age-dependent leaf senescence in rice. We constructed two specific RNAi vectors derived from the 5′-end region and 3′-UTR of OsHox33 to knockdown its expression. Transgenic plants harboring either RNAi construct displayed similar phenotypes of precocious leaf senescence symptoms, suggesting that knockdown of OsHox33 accelerates leaf senescence in rice. pOsHox33::GUS fusion expression and RT-PCR revealed that OsHox33 is highly expressed in young organs, especially in young meristems such as shoot apical meristems, intercalary meristems, and young callus. In addition, real-time PCR indicated that OsHox33 was more highly expressed in young leaves than in old leaves. To further investigate OsHox33 function, we analyzed chloroplast ultrastructure in different-aged leaves of RNAi plants, and found that OsHox33 knockdown accelerated chloroplast degradation, which is consistent with RNAi phenotypes. Finally, real-time PCR studies showed that OsHox33 can regulate the expression of GS1 and GS2, two senescence-associated genes. Taken together, the work presented here provides new insights into the function of HD-Zip III members in plants.     

Simultaneous Analysis of Anthocyanin and Non-Anthocyanin Flavonoid in Various Tissues of Different Lotus (Nelumbo) Cultivars by HPLC-DAD-ESI-MSn

A validated HPLC-DAD-ESI-MSⁿ method for the analysis of non-anthocyanin flavonoids was applied to nine different tissues of twelve lotus genotypes of Nelumbo nucifera and N. lutea, together with an optimized anthocyanin extraction and separation protocol for lotus petals. A total of five anthocyanins and twenty non-anthocyanin flavonoids was identified and quantified. Flavonoid contents and compositions varied with cultivar and tissue and were used as a basis to divide tissues into three groups characterized by kaempferol and quercetin derivatives. Influences on flower petal coloration were investigated by principal components analyses. High contents of kaempferol glycosides were detected in the petals of N. nucifera while high quercetin glycoside concentrations occurred in N. lutea. Based on these results, biosynthetic pathways leading to specific compounds in lotus tissues are deduced through metabolomic analysis of different genotypes and tissues and correlations among flavonoid compounds.     

Association of DNA Methylation at CPT1A Locus with Metabolic Syndrome in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) Study

In this study, we conducted an epigenome-wide association study of metabolic syndrome (MetS) among 846 participants of European descent in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN). DNA was isolated from CD4+ T cells and methylation at ~470,000 cytosine-phosphate-guanine dinucleotide (CpG) pairs was assayed using the Illumina Infinium HumanMethylation450 BeadChip. We modeled the percentage methylation at individual CpGs as a function of MetS using linear mixed models. A Bonferroni-corrected P-value of 1.1 x 10⁻⁷ was considered significant. Methylation at two CpG sites in CPT1A on chromosome 11 was significantly associated with MetS (P for cg00574958 = 2.6x10^-14 and P for cg17058475 = 1.2x10^-9). Significant associations were replicated in both European and African ancestry participants of the Bogalusa Heart Study. Our findings suggest that methylation in CPT1A is a promising epigenetic marker for MetS risk which could become useful as a treatment target in the future.     

The Acoustic Properties of Low Intensity Vocalizations Match Hearing Sensitivity in the Webbed-Toed Gecko,Gekko subpalmatus

The design of acoustic signals and hearing sensitivity in socially communicating species would normally be expected to closely match in order to minimize signal degradation and attenuation during signal propagation. Nevertheless, other factors such as sensory biases as well as morphological and physiological constraints may affect strict correspondence between signal features and hearing sensitivity. Thus study of the relationships between sender and receiver characteristics in species utilizing acoustic communication can provide information about how acoustic communication systems evolve. The genus Gekko includes species emitting high-amplitude vocalizations for long-range communication (loud callers) as well as species producing only low-amplitude vocalizations when in close contact with conspecifics (quiet callers) which have rarely been investigated. In order to investigate relationships between auditory physiology and the frequency characteristics of acoustic signals in a quiet caller, Gekko subpalmatus we measured the subjects’ vocal signal characteristics as well as auditory brainstem responses (ABRs) to assess auditory sensitivity. The results show that G. subpalmatus males emit low amplitude calls when encountering females, ranging in dominant frequency from 2.47 to 4.17 kHz with an average at 3.35 kHz. The auditory range with highest sensitivity closely matches the dominant frequency of the vocalizations. This correspondence is consistent with the notion that quiet and loud calling species are under similar selection pressures for matching auditory sensitivity with spectral characteristics of vocalizations.     

A simple and biosafe method for isolation of human umbilical vein endothelial cells

Human umbilical vein endothelial cells (HUVEC_S) are used as an irreplaceable tool for the study of vascular diseases. However, the technicians who isolate HUVECs are largely exposed to potential infectious threats. Here we report the development of a specialized instrument to protect researchers from known or unknown infectious agents when they operate on human umbilical cords. This instrument can be assembled by common laboratory supplies and adapted to accommodate umbilical cords of different lengths. When the cord is enclosed within the instrument, the risk of sample contamination and operator infection is greatly reduced. Using our instrument, endothelial cells were successfully isolated from human umbilical veins without contamination. The cells were verified by their cobblestone-like morphology and by immunofluorescence staining (Factor VIII and CD31 positivity and α-SMA negativity). Our instrument simplifies and optimizes the cell extraction process, and most importantly elevates the biosafety to a higher level during the isolation of human umbilical vein endothelial cells.     

Genomic constitution and taxonomy of the Chinese hexaploids Elymus cylindricus and E. breviaristatus (Poaceae: Triticeae)

Elymus cylindricus (2n = 6x = 42) and E. breviaristatus (2n = 6x = 42) are distributed in grasslands and deserts of northern and north‐western China. Their genomic constitution and taxonomic status are unclear. Elymus cylindricus was crossed with E. wawawaiensis J.R.Carlson & Barkworth ( StH ), Roegneria grandis Keng ( StY ) and Campeiostachys dahurica (Turcz. ex Griseb.) B.R.Baum, J.L. Y ang & C. Y en var. dahurica ( StYH ). Meiotic pairing in the hybrids E. cylindricus × E. wawawaiensis ( StH ), E. cylindricus × R. grandis ( StY ) and E. cylindricus × C. dahurica var. dahurica ( StYH ) showed on average 10.00, 11.30 and 20.92 bivalents per cell, respectively. Elymus breviaristatus was crossed with C. dahurica var. dahurica ( StYH ) and E. cylindricus. Chromosome pairing in the hybrids of E. breviaristatus × C. dahurica var. dahurica and E. breviaristatus × E. cylindricus showed on average 19.60 and 19.27 bivalents, respectively. Genomic in situ hybridization (GI SH ) revealed the presence of St , Y and H genomes in E. cylindricus and E. breviaristatus. An intergenomic rearrangement was observed in E. cylindricus using GI SH . Meiotic pairing data and GI SH indicated that both E. cylindricus and E. breviaristatus are allohexaploids containing the StYH genomes. Elymus cylindricus and E. breviaristatus should be treated as Campeiostachys dahurica var. cylindrica and Campeiostachys breviaristata, respectively.     

Glucose‐ and mannose‐induced stomatal closure is mediated by ROS production,Ca2+ and water channel in Vicia faba

Sugars act as vital signaling molecules that regulate plant growth, development and stress responses. However, the effects of sugars on stomatal movement have been unclear. In our study, we explored the effects of monosaccharides such as glucose and mannose on stomatal aperture. Here, we demonstrate that glucose and mannose trigger stomatal closure in a dose‐ and time‐dependent manner in epidermal peels of broad bean (Vicia faba). Pharmacological studies revealed that glucose‐ and mannose‐induced stomatal closure was almost completely inhibited by two reactive oxygen species (ROS) scavengers, catalase (CAT) and reduced glutathione (GSH), was significantly abolished by an NADPH oxidase inhibitor, diphenylene iodonium chloride (DPI), whereas they were hardly affected by a peroxidase inhibitor, salicylhydroxamic acid (SHAM). Furthermore, glucose‐ and mannose‐induced stomatal closure was strongly inhibited by a Ca²⁺ channel blocker, LaCl₃, a Ca²⁺ chelator, ethyleneglycol‐bis(beta‐aminoethylether)‐N,N'‐tetraacetic acid (EGTA) and two water channel blockers, HgCl₂ and dimethyl sulfoxide (DMSO); whereas the inhibitory effects of the water channel blockers were essentially abolished by the reversing agent β‐mercaptoethanol (β‐ME). These results suggest that ROS production mainly via NADPH oxidases, Ca²⁺ and water channels are involved in glucose‐ and mannose‐induced stomatal closure.