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21.
Characterization of two phosphate transporters from barley; evidence for diverse function and kinetic properties among members of the Pht1 family 总被引:11,自引:0,他引:11
Putative phosphate transporters have been identified in a barley (Hordeum vulgare L.) genomic library by their homology to known phosphate transporters from dicot species. The genes designated HORvu;Pht1;1 and HORvu;Pht1;6 encode proteins of 521 and 535 amino acids respectively with 12 predicted membrane-spanning domains and other motifs common to the Phtl family of phosphate transporters. HORvu;Pht1;1 is expressed exclusively in roots and is strongly induced by phosphate deprivation. HORvu;Pht1;6 is expressed in the aerial parts of the plant with strongest expression in old leaves and flag leaves. In situ hybridization showed that HORvu;Pht1;6 is expressed in the phloem of vascular bundles in leaves and ears. In order to study the biochemical properties of HORvu;Pht1;1 and HORvu;Pht1;6, the genes were expressed in transgenic rice (Oryza sativa L.) plants under the control of the rice actin promoter and suspension cell cultures were generated. Cells derived from transgenic plants were able to take up phosphate at a much higher rate than control cells, demonstrating that both genes encode functional phosphate transporters. The estimated Km for phosphate for cells expressing HORvu;Pht1;1 was 9.06 +/- 0.82 microM, which is characteristic of a high-affinity transporter. The rate of phosphate uptake decreased with increasing pH, suggesting that HORvu;Pht1;1 operates as a H+/H2PO4(-) symporter. In contrast, the estimated Km for phosphate for cells expressing HORvu;Pht1;6 was 385 +/- 61 microM, which is characteristic of a low-affinity transporter. Taken together, the results suggest that HORvu;Pht1;1 functions in uptake of phosphate at the root surface, while HORvu;Pht1;6 probably functions in remobilization of stored phosphate from leaves. 相似文献
22.
Jemal M Rao S Gatz M Whigan D 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,795(2):273-289
A selective, accurate, and reproducible LC/MS/MS assay was developed and validated for the determination of the HIV protease inhibitor atazanavir (BMS-232632) in human peripheral blood mononuclear cells (PBMC) samples. In addition to the details of the validated LC/MS/MS method, a practical procedure is described in great detail for the preparation of large supplies of control (blank) PBMC from units of blood (each unit of blood is about 500 ml) for making the calibration standards and quality control (QC) samples. The PBMC assay design, intended for high-throughput sample analysis, is also described in some detail in regards to the composition and concentration expressions of the calibration standards and QC samples, the lysing procedure of the PBMC samples, and the final analysis/quantitation procedure. The method involved automated solid-phase extraction (SPE) of atazanavir and a stable isotope analog internal standard (I.S.) using 3M Empore C2-SD 96-well plates. A portion of the reconstituted sample residue was injected onto a YMC Basic analytical column which was connected to a triple quad mass spectrometer for analyte determination by positive-ion electrospray in the selected reaction monitoring (SRM) mode. The standard curve, which ranged from 5 to 2500 fmol per one million cells (fmol/10(6) cells), was fitted to a quadratic regression model weighted by 1/concentration. The lower limit of quantitation (LLOQ) was 5 fmol/10(6) cells. The inter- and intra-run coefficients of variation (CV) for the assay were <9% and the accuracy was 94-104%. Atazanavir was stable in PBMC for at least 24h at room temperature and for at least 129 days at -15 degrees C. 相似文献
23.
Barbisan LF Scolastici C Miyamoto M Salvadori DM Ribeiro LR da Eira AF de Camargo JL 《Genetics and molecular research : GMR》2003,2(3):295-308
The effects of crude extracts of the mushroom Agaricus blazei Murrill (Agaricaceae) on both DNA damage and placental form glutathione S-transferase (GST-P)-positive liver foci induced by diethylnitrosamine (DEN) were investigated. Six groups of adult male Wistar rats were used. For two weeks, animals of groups 3 to 6 were treated with three aqueous solutions of A. blazei (mean dry weight of solids being 1.2, 5.6, 11.5 and 11.5 mg/ml, respectively). After this period, groups 2 to 5 were given a single ip injection 200 mg/kg DEN and groups 1 and 6 were treated with 0.9% NaCl. All animals were subjected to 70% partial hepatectomy at week five and sacrificed 4, 24 and 48 h or 8 weeks after DEN or 0.9% NaCl treatments (10th week after the beginning of the experiment). The alkaline comet assay and GST-P-positive liver foci development were used to evaluate the influence of the mushroom extracts on liver cell DNA damage and on the initiation of liver carcinogenesis, respectively. Previous treatment with the highest concentration of A. blazei (11.5 mg/ml) significantly reduced DNA damage, indicating a protective effect against DEN-induced liver cytotoxicity/genotoxicity. However, the same dose of mushroom extract significantly increased the number of GST-P-positive liver foci. 相似文献
24.
25.
Acetone extract of Elephantopus scaber, an ethnomedicnal plant, reduced the blood glucose levels in streptozotocin-induced diabetic rats significantly. Acute toxicity studies revealed the non-toxic nature of the crude extract. Fractionation of the acetone extract yielded a new steroid, 28Nor-22(R)Witha 2,6,23-trienolide. Biological testing of the compound demonstrated a significant antidiabetic activity by reducing the elevated blood glucose levels and restoring the insulin levels in streptozotocin-induced diabetic rats. This compound can be a useful candidate to treat diabetes. 相似文献
26.
Sin-Fen Hu Yu-Hsin Huang Chan-Pin Lin Li-Yu Daisy Liu Syuan-Fei Hong Chiao-Yin Yang Hsiao-Feng Lo Ting-Yu Tseng Wei-Yao Chen Shih-Shun Lin 《PloS one》2015,10(6)
PHYL1 and SAP54 are orthologs of pathogenic effectors of Aster yellow witches’-broom (AYWB) phytoplasma and Peanut witches’-broom (PnWB) phytoplasma, respectively. These effectors cause virescence and phyllody symptoms (hereafter leafy flower) in phytoplasma-infected plants. T0 lines of transgenic Arabidopsis expressing the PHYL1 or SAP54 genes (PHYL1 or SAP54 plants) show a leafy flower phenotype and result in seedless, suggesting that PHYL1 and SAP54 interfere with reproduction stage that restrict gain-of-function studies in the next generation of transgenic plants. Turnip mosaic virus (TuMV) mild strain (TuGK) has an Arg182Lys mutation in the helper-component proteinase (HC-ProR182K) that blocks suppression of the miRNA pathway and prevents symptom development in TuGK-infected plants. We exploited TuGK as a viral vector for gain-of-function studies of PHYL1 and SAP54 in Arabidopsis plants. TuGK-PHYL1- and TuGK-SAP54-infected Arabidopsis plants produced identical leafy flower phenotypes and similar gene expression profiles as PHYL1 and SAP54 plants. In addition, the leafy flower formation rate was enhanced in TuGK-PHYL1- or TuGK-SAP54-infected Arabidopsis plants that compared with the T0 lines of PHYL1 plants. These results provide more evidence and novel directions for further studying the mechanism of PHYL1/SAP54-mediated leafy flower development. In addition, the TuGK vector is a good alternative in transgenic plant approaches for rapid gene expression in gain-of-function studies. 相似文献
27.
In-Kyu Yoon Maria Theresa Alera Catherine B. Lago Ilya A. Tac-An Daisy Villa Stefan Fernandez Butsaya Thaisomboonsuk Chonticha Klungthong Jens W. Levy John Mark Velasco Vito G. Roque Jr. Henrik Salje Louis R. Macareo Laura L. Hermann Ananda Nisalak Anon Srikiatkhachorn 《PLoS neglected tropical diseases》2015,9(5)
Background
Chikungunya virus (CHIKV) is a globally re-emerging arbovirus for which previous studies have indicated the majority of infections result in symptomatic febrile illness. We sought to characterize the proportion of subclinical and symptomatic CHIKV infections in a prospective cohort study in a country with known CHIKV circulation.Methods/Findings
A prospective longitudinal cohort of subjects ≥6 months old underwent community-based active surveillance for acute febrile illness in Cebu City, Philippines from 2012-13. Subjects with fever history were clinically evaluated at acute, 2, 5, and 8 day visits, and at a 3-week convalescent visit. Blood was collected at the acute and 3-week convalescent visits. Symptomatic CHIKV infections were identified by positive CHIKV PCR in acute blood samples and/or CHIKV IgM/IgG ELISA seroconversion in paired acute/convalescent samples. Enrollment and 12-month blood samples underwent plaque reduction neutralization test (PRNT) using CHIKV attenuated strain 181/clone25. Subclinical CHIKV infections were identified by ≥8-fold rise from a baseline enrollment PRNT titer <10 without symptomatic infection detected during the intervening surveillance period. Selected CHIKV PCR-positive samples underwent viral isolation and envelope protein-1 gene sequencing. Of 853 subjects who completed all study procedures at 12 months, 19 symptomatic infections (2.19 per 100 person-years) and 87 subclinical infections (10.03 per 100 person-years) occurred. The ratio of subclinical-to-symptomatic infections was 4.6:1 varying with age from 2:1 in 6 month-5 year olds to 12:1 in those >50 years old. Baseline CHIKV PRNT titer ≥10 was associated with 100% (95%CI: 46.1, 100.0) protection from symptomatic CHIKV infection. Phylogenetic analysis demonstrated Asian genotype closely related to strains from Asia and the Caribbean.Conclusions
Subclinical infections accounted for a majority of total CHIKV infections. A positive baseline CHIKV PRNT titer was associated with protection from symptomatic CHIKV infection. These findings have implications for assessing disease burden, understanding virus transmission, and supporting vaccine development. 相似文献28.
Spatio‐temporal variation in European starling reproductive success at multiple small spatial scales
Understanding population dynamics requires spatio‐temporal variation in demography to be measured across appropriate spatial and temporal scales. However, the most appropriate spatial scale(s) may not be obvious, few datasets cover sufficient time periods, and key demographic rates are often incompletely measured. Consequently, it is often assumed that demography will be spatially homogeneous within populations that lack obvious subdivision. Here, we quantify small‐scale spatial and temporal variation in a key demographic rate, reproductive success (RS), within an apparently contiguous population of European starlings. We used hierarchical cluster analysis to define spatial clusters of nest sites at multiple small spatial scales and long‐term data to test the hypothesis that small‐scale spatio‐temporal variation in RS occurred. RS was measured as the number of chicks alive ca. 12 days posthatch either per first brood or per nest site per breeding season (thereby incorporating multiple breeding attempts). First brood RS varied substantially among spatial clusters and years. Furthermore, the pattern of spatial variation was stable across years; some nest clusters consistently produced more chicks than others. Total seasonal RS also varied substantially among spatial clusters and years. However, the magnitude of variation was much larger and the pattern of spatial variation was no longer temporally consistent. Furthermore, the estimated magnitude of spatial variation in RS was greater at smaller spatial scales. We thereby demonstrate substantial spatial, temporal, and spatio‐temporal variation in RS occurring at very small spatial scales. We show that the estimated magnitude of this variation depended on spatial scale and that spatio‐temporal variation would not have been detected if season‐long RS had not been measured. Such small‐scale spatio‐temporal variation should be incorporated into empirical and theoretical treatments of population dynamics. 相似文献
29.
Sammy De Grave Kevin G. Smith Nils A. Adeler Dave J. Allen Fernando Alvarez Arthur Anker Yixiong Cai Savrina F. Carrizo Werner Klotz Fernando L. Mantelatto Timothy J. Page Jhy-Yun Shy José Luis Villalobos Daisy Wowor 《PloS one》2015,10(3)
We present the first global assessment of extinction risk for a major group of freshwater invertebrates, caridean shrimps. The risk of extinction for all 763 species was assessed using the IUCN Red List criteria that include geographic ranges, habitats, ecology and past and present threats. The Indo-Malayan region holds over half of global species diversity, with a peak in Indo-China and southern China. Shrimps primarily inhabit flowing water; however, a significant subterranean component is present, which is more threatened than the surface fauna. Two species are extinct with a further 10 possibly extinct, and almost one third of species are either threatened or Near Threatened (NT). Threats to freshwater shrimps include agricultural and urban pollution impact over two-thirds of threatened and NT species. Invasive species and climate change have the greatest overall impact of all threats (based on combined timing, scope and severity of threats). 相似文献
30.
Bullatantriol has been isolated from Annona bullata. Its constitution and relative configuration have been established by X-ray analysis. Its absolute configuration has been assigned by chiroptical investigation of the corresponding 7-ketone. 相似文献