Caractérisation biochimique des cépages de Vitis vinifera L. par électrophorèse d'isoenzymes foliaires: Essai de classification des variétés

Biochemical characterization of Vitis vinifera L. cultivars by electrophoresis of leaf isoenzymes:An attempt to classify grapevine varietiesA number of 40 Vitis vinifera varieties commonly grown in France could be characterized by disc-electrophores is of isoenzymes. Starting from forced cuttings, this technique allows to ana!yze a large number of plants at any time of the year; only low quantities of leaf material are needed and no enzyme purification is necessary. Among 39 bands identified from 3 enzyme systems, 31 were variable: 19, 8 and 4 isoenzymes, respectively, of a-esterase (a-EST), glutamate oxaloacetate transaminase (GOT) and acid phosphatase (PHA).Combinations of these bands allowed to characterize each variety. 13 groups of rela ted varieties could be established by multivariate analysis of the presence versus absence of bands. The 7 best characterized groups gather varieties which, according to ampelographic classification, are grouped in the same way. The interrelations between isoenzymes and certain ampelographic characters or the presumed geographic origin of the varieties allow to propose a statistical interpretation of the enzymatic classification

Estrogen Receptor-Alpha 36 Mediates Mitogenic Antiestrogen Signaling in ER-Negative Breast Cancer Cells

It is prevailingly thought that the antiestrogens tamoxifen and ICI 182, 780 are competitive antagonists of the estrogen-binding site of the estrogen receptor-alpha (ER-α). However, a plethora of evidence demonstrated both antiestrogens exhibit agonist activities in different systems such as activation of the membrane-initiated signaling pathways. The mechanisms by which antiestrogens mediate estrogen-like activities have not been fully established. Previously, a variant of ER-α, EP–α36, has been cloned and showed to mediate membrane-initiated estrogen and antiestrogen signaling in cells only expressing ER-α36. Here, we investigated the molecular mechanisms underlying the antiestrogen signaling in ER-negative breast cancer MDA-MB-231 and MDA-MB-436 cells that express high levels of endogenous ER-α36. We found that the effects of both 4-hydoxytamoxifen (4-OHT) and ICI 182, 780 (ICI) exhibited a non-monotonic, or biphasic dose response curve; antiestrogens at low concentrations, elicited a mitogenic signaling pathway to stimulate cell proliferation while at high concentrations, antiestrogens inhibited cell growth. Antiestrogens at l nM induced the phosphorylation of the Src-Y416 residue, an event to activate Src, while at 5 µM induced Src-Y527 phosphorylation that inactivates Src. Antiestrogens at 1 nM also induced phosphorylation of the MAPK/ERK and activated the Cyclin D1 promoter activity through the Src/EGFR/STAT5 pathways but not at 5 µM. Knock-down of ER-α36 abrogated the biphasic antiestrogen signaling in these cells. Our results thus indicated that ER-α36 mediates biphasic antiestrogen signaling in the ER-negative breast cancer cells and Src functions as a switch of antiestrogen signaling dependent on concentrations of antiestrogens through the EGFR/STAT5 pathway

Gene transfer into Xenopus hepatocytes: transcriptional regulation by members of the nuclear receptor superfamily.

A procedure to culture Xenopus laevis hepatocytes that allows the cells in primary culture to be subjected to gene transfer experiments has been developed. The cultured cells continue to present tissue-specific markers such as expression of the albumin gene or estrogen-controlled vitellogenin gene expression, which are both restricted to liver. Two efficient and reproducible gene transfer procedures have been adapted to the Xenopus hepatocytes, namely lipofection and calcium phosphate-mediated precipitation. The transcription of transfected reporter genes controlled by estrogen-, glucocorticoid- or peroxisome proliferator-response elements was stimulated by endogenous or co-transfected receptor in a ligand-dependent manner. Furthermore, the expression of a reporter gene under the control of the entire promoter of the vitellogenin B1 gene mimicked the expression of the chromosomal vitellogenin gene with respect to basal and estrogen-induced activity. Thus, this culture-transfection system will prove very useful to study the regulation of genes expressed in the liver under the control of various hormones or xenobiotics

Functional interactions of peroxisome proliferator-activated receptor, retinoid-X receptor, and Sp1 in the transcriptional regulation of the acyl-coenzyme-A oxidase promoter.

Peroxisome proliferator-activated receptor (PPARs) are members of the nuclear receptor superfamily. For transcriptional activation of their target genes, PPARs heterodimerize with the retinoid-X receptor (RXR). The convergence of the PPAR and RXR signaling pathways has been shown to have an important function in lipid metabolism. The promoter of the gene encoding the acyl-coenzyme-A oxidase (ACO), the rate-limiting enzyme in peroxisomal beta-oxidation of fatty acids, is a target site of PPAR action. In this study, we examined the role and the contribution of both cis-and trans-acting factors in the transcriptional regulation of this gene using transient transfections in insect cells. We identified several functional cis-acting elements present in the promoter of the ACO gene and established that PPAR-dependent as well as PPAR-independent mechanisms can activate the ACO promoter in these cells. We show that the PPAR/RXR heterodimer exerts its effect through two response elements within the ACO promoter, in synergy with the transcription factor Sp1 via five Sp1-binding sites. Furthermore, this functional interaction also occurs when Sp1 is co-expressed with PPAR or RXR alone, indicating that activation can occur independently of PPAR/RXR heterodimers

Thermal energy storage using desert sand : a numerical study of the thermofluidic performances

The Thermal Energy Storage (TES) enhances the availability of renewable energy plants. It reduces the mismatch between the production and the demand of the electric energy. However, the high cost of the TES leads to a high overall cost of the produced electric kWh. In the case of solar power plants built in Saharan regions, the use of sand as the storing medium in the TES is a priori a suitable technique that can solve this problem. In fact, the sand presents good physical and chemical properties and it is locally available with a very low cost. In this paper, a numerical study has been conducted to assess the thermal and fluidic performances of a fixed bed and of a fluidized bed by using sand as storing medium. The heat is transferred to, and from, the sand by air. 2D and 3D simulations are conducted. The temperature profiles of the bed are examined as well as the storing rates. Parametric studies with the air speed and the height of the bed were considered. The results gained in this paper indicate that it is very viable and promising to integrate sand as storing media in the solar thermal applications especially where this material is plentiful.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016