Transcription and splicing regulation in human umbilical vein endothelial cells under hypoxic stress conditions by exon array

<p>Abstract</p> <p>Background</p> <p>The balance between endothelial cell survival and apoptosis during stress is an important cellular process for vessel integrity and vascular homeostasis, and it is also pivotal in angiogenesis during the development of many vascular diseases. However, the underlying molecular mechanisms remain largely unknown. Although both transcription and alternative splicing are important in regulating gene expression in endothelial cells under stress, the regulatory mechanisms underlying this state and their interactions have not yet been studied on a genome-wide basis.</p> <p>Results</p> <p>Human umbilical vein endothelial cells (HUVECs) were treated with cobalt chloride (CoCl₂) both to mimic hypoxia and to induce cell apoptosis and alternative splicing responses. Cell apoptosis rate analysis indicated that HUVECs exposed to 300 μM CoCl₂for 24 hrs were initially counterbalancing apoptosis with cell survival. We therefore used the Affymetrix exon array system to determine genome-wide transcript- and exon-level differential expression. Other than 1583 differentially expressed transcripts, 342 alternatively spliced exons were detected and classified by different splicing types. Sixteen alternatively spliced exons were validated by RT-PCR. Furthermore, direct evidence for the ongoing balance between HUVEC survival and apoptosis was provided by Gene Ontology (GO) and protein function, as well as protein domain and pathway enrichment analyses of the differentially expressed transcripts. Importantly, a novel molecular module, in which the heat shock protein (HSP) families play a significant role, was found to be activated under mimicked hypoxia conditions. In addition, 46% of the transcripts containing stress-modulated exons were differentially expressed, indicating the possibility of combinatorial regulation of transcription and splicing.</p> <p>Conclusion</p> <p>The exon array system effectively profiles gene expression and splicing on the genome-wide scale. Based on this approach, our data suggest that transcription and splicing not only regulate gene expression, but also carry out combinational regulation of the balance between survival and apoptosis of HUVECs under mimicked hypoxia conditions. Since cell survival following the apoptotic challenge is pivotal in angiogenesis during the development of many vascular diseases, our results may advance the knowledge of multilevel gene regulation in endothelial cells under physiological and pathological conditions.</p

Short Communication Response of NAD(P)H dehydrogenase complex to the alteration of CO 2 concentration in the cyanobacterium Synechocystis PCC6803

Summary An NADPH-specific NDH-1 sub-complex was separated by native-polyacrylamide gel electrophoresis and detected by activity staining from the whole cell extracts of Synechocystis PCC6803. Low CO 2 caused an increase in the activity of this sub-complex quickly, accompanied by an evident increase in the expression of NdhK and PSI-driven NADPH oxidation activity that can reflect the activity of NDH-1-mediated cyclic electron transport. During incubation with high CO 2 , the activities of NDH-1 sub-complex and PSI-driven NADPH oxidation as well as the protein level of NdhK slightly increased at the beginning, but decreased evidently in various degrees along with incubation time. These results suggest that CO 2 concentration in vitro as a signal can control the activity of NDH-1 complex, and NDH-1 complex may in turn function in the regulation of CO 2 uptake. Key words: CO 2 concentration -CO 2 uptake -NAD(P)H dehydrogenase -Synechocystis PCC6803 Abbreviations: CCM = CO 2 concentrating mechanism. -DCMU = 3-(3,4-dichlorophenyl)-1,1-dimethylurea. -H-cells = cells grown in high CO 2 . -L-cells = cells grown in low CO 2 . -NBT = nitroblue tetrazolium. -NDH-1 = type 1 NAD(P)H dehydrogenase. -PAGE = polyacrylamide gel electrophoresi

LOS Signal Identification Based on Common Chord Intersection Point Position Deviation from MS in Target Localization

Target localization has been a popular research topic in recent years since it is the basis of all kinds of location-based applications. For GNSS-denied urban or indoor environments, the localization method based on time-of-arrival (TOA) is one of the most popular localization methods due to its high accuracy and simplicity. However, the Non-line-of-sight (NLOS) error is the major cause that degrades the accuracy of the TOA-based localization method. Identifying whether a received signal at a base station (BS) is due to a line-of-sight (LOS) transmission or NLOS is the key to TOA-based localization methods. In the popular LOS signal identification methods, compared with statistic signal methods and machine learning methods, the geometric constraint method has the advantages of simplicity and without requiring priori knowledge of signals and large amounts of training datasets. In this paper, we propose a geometric constraint two-step LOS signal identification method based on common chord intersection point position deviation from mobile stations (MS). In the first step, all BSs are divided into multiple BS combinations with every three BSs, the TOA distance error of each BS combination is estimated based on common chord intersection point position deviation from MS, the BS combinations whose TOA distance error satisfy Gaussian distribution are roughly identified as LOS BS combination and enter the second step, the other BS combinations are discarded as NLOS BS combination. In the second step, based on mutual distance threshold and discrimination result matrix, common chord intersection points of LOS BS combination, and corresponding LOS BS combinations are identified. The BSs of LOS BS combinations are identified as LOS BS and the signals received at LOS BS are identified as LOS signal ultimately. Compared with the other two geometric constraint methods, the proposed algorithm has better identification accuracy, and the setting of the identification threshold value has a theoretical basis, which facilitates the application of the proposed algorithm

Low concentrations of NaHSO3 increase cyclic photophosphorylation and photosynthesis in cyanobacterium Synechocystis PCC6803

Abstract Application of NaHSO 3 solution at low concentrations (20-200 µM) to the culture medium enhanced photosynthetic oxygen evolution in cyanobacterium Synechocystis PCC6803 by more than 10%. The slow phase of ms-DLE was strengthened, showing that the transmembrane proton motive force related to photophosphorylation was enhanced. It was also observed that dry weight as well as ATP content under illuminated conditions were both increased after the treatment, indicating that low concentrations of NaHSO 3 could enhance the supply of ATP and thus increase biomass accumulation. In accord with the promotion in the photosynthetic oxygen evolution and ATP content, the transient increase in chlorophyll fluorescence after the termination of actinic light was increased; and meanwhile, the half-time of re-reduction of P700 + in the presence of DCMU after a pulse light under background far-red light was shortened by approximately 30%, indicating that cyclic electron flow around PS I was accelerated by the treatment. Based on these results it is suggested that the increase in photosynthesis in Synechocystis PCC6803 caused by low concentrations of NaHSO 3 solution might be due to the stimulation of the cyclic electron flow around PS I and thus the increase in photophosphorylation. Abbreviations: AL -actinic light; Chl -chlorophyll; Chl fluorescence -chlorophyll a fluorescence; DCMU -3-(3,4-dichlorophenyl)-1,1-dimethylurea; ms-DLE -millisecond delayed light emission; Fd -ferredoxin; F mmaximal yield of chlorophyll a fluorescence; F o -intensity of chlorophyll a fluorescence of dark-adapted sample with measuring beam of negligible actinic intensity; FR -far-red light; F v -variable fluorescence during induction; MT -multiple-turnover light (50 ms pulse light); PS -Photosystem; PS I -Photosystem I; PS II -Photosystem II; P700 -reaction center chlorophylls of PS I; Pn -net photosynthetic rate of CO 2 uptake or oxygen evolution; PQ -plastoquinone; PSP -photophosphorylatio

The Relationships between Process Parameters and Polymeric Nanofibers Fabricated Using a Modified Coaxial Electrospinning

The concrete relationship between the process parameters and nanoproduct properties is an important challenge for applying nanotechnology to produce functional nanomaterials. In this study, the relationships between series of process parameters and the medicated nanofibers&rsquo; diameter were investigated. With an electrospinnable solution of hydroxypropyl methylcellulose (HPMC) and ketoprofen as the core fluid, four kinds of nanofibers were prepared with ethanol as a sheath fluid and under the variable applied voltages. Based on these nanofibers, a series of relationships between the process parameters and the nanofibers&rsquo; diameters (D) were disclosed, such as with the height of the Taylor cone (H, D = 125 + 363H), with the angle of the Taylor cone (&alpha;, D = 1576 &minus; 19&alpha;), with the length of the straight fluid jet (L, D = 285 + 209L), and with the spreading angle of the instable region (&theta;, D = 2342 &minus; 43&theta;). In vitro dissolution tests verified that the smaller the diameters, the faster ketoprofen (KET) was released from the HPMC nanofibers. These concrete process-property relationships should provide a way to achieve new knowledge about the electrostatic energy-fluid interactions, and to meanwhile improve researchers&rsquo; capability to optimize the coaxial process conditions to achieve the desired nanoproducts

Large-Scale Ligand-Free Synthesis of Homogeneous Core-Shell Quantum-Dot-Modified Cs4PbBr6 Microcrystals

An organic ligand-free solution method is developed for preparing homogeneous core shell quantum-dot (QD)-modified pure Cs4PbBr6 microcrystals on a large scale (similar to 12 g) at room temperature. The ligand-free Cs4PbBr6 microcrystals show a high green photoluminescence quantum yield of 76% with 360 nm of excitation light, which is attributed to their unique microarchitecture, with several features including quantum confinement of the outer QDs, stability of the inner Cs4PbBr6 microcrystals, improved light trapping, and interfacial recombination. UV-vis-near-IR and photoluminescence analyses provide valued evidence to support the ligand-free Cs4PbBr6 with synergy between the QDs and microcrystals