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1.
Lipid and lipoprotein metabolism in Hep G2 cells 总被引:6,自引:0,他引:6
S R Wang M Pessah J Infante D Catala C Salvat R Infante 《Biochimica et biophysica acta》1988,961(3):351-363
Lipid composition, lipid synthesis and lipoprotein secretion by the Hep G2 cell line have been studied with substrate and insulin supplied under different conditions. The lipid composition of Hep G2 cells was close to that of normal human liver, except for a higher content in sphingomyelin (P less than 0.005) and a lower phosphatidylcholine/sphingomyelin ratio. Most of the [14C]triacylglycerols secreted into the medium were recovered by ultracentrifugation at densities of 1.006 to 1.020 g/ml. The main apolipoproteins secreted were apo B-100 and apo A-I. Hep G2 mRNA synthesized in vitro the pro-apolipoproteins A-I and E. Triacylglycerol secretion was 7.38 +/- 1.04 micrograms/mg cell protein per 20 h with 5.5 mM glucose in the medium and increased linearly with glucose concentration. Oleic acid (1 mM) increased the incorporation of [3H]glycerol into the medium and cell triacylglycerols by 251 and 899%, with a concomitant increment in cell triacylglycerols and cholesterol ester. Insulin (1 mU or 7 pmol/ml) inhibited triacylglycerol secretion and [35S]methionine incorporation into secreted protein by 47 and 28%, respectively, with a corresponding increase in the cells. Preincubation of cells with 2.5-10 mM mevalonolactone decreased the incorporation of [14C]acetate into cholesterol 6.2-fold, indicating an inhibitory effect on HMG-CoA reductase. It is concluded that in spite of some differences between Hep G2 and normal human hepatocytes, this line offers an alternative and reliable model for studies on liver lipid metabolism. 相似文献
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Salvat A Antonnacci L Fortunato RH Suarez EY Godoy HM 《Letters in applied microbiology》2001,32(5):293-297
AIMS: Screening of antimicrobial activity in 25 plant species from Northern Argentina. METHODS AND RESULTS: Inhibition of microbial growth was measured by a microplate assay with an oxidation-reduction indicator (Alamar Blue). Test organisms were: Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecium. Weak inhibitory activities (MIC=0.5 mg dry matter ml(-1)) were found in methanolic extracts of Rivina humilis, Crateva tapia, Funastrum claucum and Schinopsis balansae. Stronger bacteriostatic power was detected in Vassobia breviflora (MIC=0.25 mg ml(-1) against Staphylococcus aureus, and 0.5 mg ml(-1) against Enterococcus faecium). This activity was purified five-fold by extraction with dichloromethane, and it was found equally effective against susceptible or antibiotic-resistant strains of Staph. aureus. In addition, the purified extract was synergistic with gentamicin, and it was bactericidal at 24 h, with a concentration of 0.25 mg ml(-1). CONCLUSION: There is a significant antimicrobial activity in Vassobia breviflora. SIGNIFICANCE AND IMPACT OF THE STUDY: Further studies will be required to disclose the potential importance of these findings. 相似文献
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V. Laurent S. Planes B. Salvat 《Biological journal of the Linnean Society. Linnean Society of London》2002,77(2):221-231
Nine populations of giant clams, Tridacna maxima, from six islands of French Polynesia were screened for allozyme variation at ten polymorphic loci. The genetic structure of populations of T. maxima were studied at different spatial scales: within an island, between islands of the same archipelago and between archipelagos. Significant genetic differences were observed only between populations from different archipelagos, and genetic differentiation was correlated with geographical separation. However, these results were only supported by a single locus, PEP * and all other loci were homogeneous between studied populations. According to Lewontin & Krakauer's model, the genetic structure can be explained by selection. The selective factors most likely depend on the respective habitat of each archipelago. We also studied genotype–phenotype correlation using the colour of the clam mantle, and did not find any relationship between the mantle colour and the genetic structure of the individuals. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 221–231. 相似文献
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Regina Salvat Leonard Moise Chris Bailey-Kellogg Karl E. Griswold 《Journal of visualized experiments : JoVE》2014,(85)
Biochemical assays with recombinant human MHC II molecules can provide rapid, quantitative insights into immunogenic epitope identification, deletion, or design1,2. Here, a peptide-MHC II binding assay is scaled to 384-well format. The scaled down protocol reduces reagent costs by 75% and is higher throughput than previously described 96-well protocols1,3-5. Specifically, the experimental design permits robust and reproducible analysis of up to 15 peptides against one MHC II allele per 384-well ELISA plate. Using a single liquid handling robot, this method allows one researcher to analyze approximately ninety test peptides in triplicate over a range of eight concentrations and four MHC II allele types in less than 48 hr. Others working in the fields of protein deimmunization or vaccine design and development may find the protocol to be useful in facilitating their own work. In particular, the step-by-step instructions and the visual format of JoVE should allow other users to quickly and easily establish this methodology in their own labs. 相似文献
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An assessment of natural stocks of the commercially important black pearl oyster, Pinctada margaritifera, was conducted in the lagoon of Takapoto Atoll, French Polynesia. The sampling methodology combined estimates of reef area
from remote sensing, depth profiles across the lagoon, and in situ sampling using scuba. Confidence limits around estimates
of mean oyster density began to stabilize after ten dives, and did not decrease further after 30. Densities of oysters increased
steadily with depth, ranging from a mean of 1 per 100 m2 at 0–10 m to 8/100 m2 at 30–40 m. More than half of the stock occurred at depths greater than 30 m. The total stock was estimated to be 4.3 ± 0.67
million, equivalent to 834 metric tonnes (including shells).
Accepted: 15 June 1999 相似文献
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Biosecurity-based interventions and strategies to reduce Campylobacter spp. on poultry farms 总被引:1,自引:0,他引:1
Newell DG Elvers KT Dopfer D Hansson I Jones P James S Gittins J Stern NJ Davies R Connerton I Pearson D Salvat G Allen VM 《Applied and environmental microbiology》2011,77(24):8605-8614
The prevention and control of Campylobacter colonization of poultry flocks are important public health strategies for the control of human campylobacteriosis. A critical review of the literature on interventions to control Campylobacter in poultry on farms was undertaken using a systematic approach. Although the focus of the review was on aspects appropriate to the United Kingdom poultry industry, the research reviewed was gathered from worldwide literature. Multiple electronic databases were employed to search the literature, in any language, from 1980 to September 2008. A primary set of 4,316 references was identified and scanned, using specific agreed-upon criteria, to select relevant references related to biosecurity-based interventions. The final library comprised 173 references. Identification of the sources of Campylobacter in poultry flocks was required to inform the development of targeted interventions to disrupt transmission routes. The approach used generally involved risk factor-based surveys related to culture-positive or -negative flocks, usually combined with a structured questionnaire. In addition, some studies, either in combination or independently, undertook intervention trials. Many of these studies were compromised by poor design, sampling, and statistical analysis. The evidence for each potential source and route of transmission on the poultry farm was reviewed critically, and the options for intervention were considered. The review concluded that, in most instances, biosecurity on conventional broiler farms can be enhanced and this should contribute to the reduction of flock colonization. However, complementary, non-biosecurity-based approaches will also be required in the future to maximize the reduction of Campylobacter-positive flocks at the farm level. 相似文献
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New sea-level data for the late Holocene period are reported from twelve atolls of the Tuamotu archipelago: Faaite, Hikueru, Marokau, Hao, Amanu, Tatakoto, Pukarua, Nukutavake, Vairaatea, Tureia, Nukutipipi, and Hereheretue. The data come from coral conglomerate outcrops, coral colonies in growth position, in situ reef framework and marine notches; they give consistent results, and their ages are controlled by 29 radiocarbon datings. The Holocene MSL remained 0.8±0.2 m higher than at present, from before 4000 years BP until at least 1500 years BP, then dropped gradually to the present level. This pattern is very similar to that reported from the northwest Tuamotus, suggesting the absence of measurable differential vertical movements over a distance greater than 1300 km during the late Holocene. Effects of the 1983 cyclones on reef morphology are reported from some atolls and radiocarbon dates of some storm-generated reef blocks are given. 相似文献