Withdrawal of survival factors results in activation of the JNK pathway in neuronal cells leading to Fas ligand induction and cell death

The JNK pathway modulates AP-1 activity. While in some cells it may have proliferative and protective roles, in neuronal cells it is involved in apoptosis in response to stress or withdrawal of survival signals. To understand how JNK activation leads to apoptosis, we used PC12 cells and primary neuronal cultures. In PC12 cells, deliberate JNK activation is followed by induction of Fas ligand (FasL) expression and apoptosis. JNK activation detected by c-Jun phosphorylation and FasL induction are also observed after removal of either nerve growth factor from differentiated PC12 cells or KCl from primary cerebellar granule neurons (CGCs). Sequestation of FasL by incubation with a Fas-Fc decoy inhibits apoptosis in all three cases. CGCs derived from gld mice (defective in FasL) are less sensitive to apoptosis caused by KCl removal than wild-type neurons. In PC12 cells, protection is also conferred by a c-Jun mutant lacking JNK phosphoacceptor sites and a small molecule inhibitor of p38 mitogen-activated protein kinase and JNK, which inhibits FasL induction. Hence, the JNK-to-c-Jun-to-FasL pathway is an important mediator of stress-induced neuronal apoptosis.     

Trifluoperazine increases fatty acid turnover in phospholipids in cultured human fibroblasts

A 24-hr pretreatment of cultured human fibroblasts with trifluoperazine induced a marked increase in incorporation of saturated (stearic, palmitic) and unsaturated (oleic, arachidonic) fatty acids into phospholipids (1.5- to 2-fold for 5.10⁻⁵ M trifluoperazine). Concomitantly, incorporation into cholesteryl esters was strongly inhibited (20% of control for 5.10⁻⁵ M trifluoperazine). The drug did not change the phospholipid composition of treated cells. The effect of trifluoperazine on oleic acid incorporation into phospholipids was time-dependent and reached a maximum after a six-hr preincubation with the drug. Trifluoperazine also induced an increase in the rate of chase of oleic acid from the different phospholipid classes. In vitro preincubation of cell-free extracts with trifluoperazine resulted in activation of phospholipid acyltransferases, whereas cholesterol acyltransferase activity was decreased. The rapid effect of trifluoperazine together with its effect on a cell-free system suggests a direct action of this amphiphilic drug on the acyltransferase activities, probably by modification of the structural organization of cellular membranes.     

Perception of traditional food products in six European regions using free word association

A total of 721 consumers were interviewed in order to obtain and compare consumer-driven associations to the word “Traditional”, in a food context, in six European regions. Participants, who were individually interviewed, had to state the first words that came into their mind when the word “Traditional” was verbally presented. Frequencies of occurrence of associations were obtained and analysed by means of simple correspondence analysis. The different word associations obtained were classified in 55 classes and then grouped in ten principal dimensions by triangulation. In general, southern European regions tended to associate the concept of “Traditional” more frequently with broad concepts such as heritage, culture or history. Central and Nordic European regions tended to focus mainly on practical issues such as convenience, health or appropriateness. As a final outcome of the analyses, a consensus conceptual map of traditional food products was obtained. The empirical findings of this qualitative exploratory free word association test provide valuable insights for product positioning, innovation and new developments in the traditional food market.     

<Emphasis Type="Italic">Medicago truncatula</Emphasis> Oleanolic-Derived Saponins Are Correlated with Caterpillar Deterrence

Plant resistance mechanisms to insect herbivory can potentially be bred into crops as an important strategy for integrated pest management. Medicago truncatula ecotypes inoculated with the rhizobium Ensifer medicae (Sinorhizobium medica) WSM419 were screened for resistance to herbivory by caterpillars of the beet armyworm, Spodoptera exigua, through leaf and whole plant choice studies; TN1.11 and F83005.5 are identified as the least and most deterrent ecotypes, respectively. In response to caterpillar herbivory, both ecotypes mount a robust burst of plant defensive jasmonate phytohormones. Restriction of caterpillars to either of these ecotypes does not adversely affect pest performance. This argues for an antixenosis (deterrence) resistance mechanism associated with the F83005.5 ecotype. Unbiased metabolomic profiling identified strong ecotype-specific differences in metabolite profile, particularly in the content of oleanolic-derived saponins that may act as antifeedants. Compared to the more susceptible ecotype, F83005.5 has higher levels of oleanolic-type zanhic acid- and medicagenic acid-derived compounds. Together, these data support saponin-mediated deterrence as a resistance mechanism of the F83005.5 ecotype and implicates these compounds as potential antifeedants that could be used in agricultural sustainable pest management strategies.     

Computation of low Mach thermical flows with implicit upwind methods

In order to apply a Godunov method to steady and unsteady thermical flows, we first present a truncation error analysis which proves that the Turkel preconditioned Roe splitting is applicable to flows modelized by the classical low Mach number model, including thermics. The impact of the Turkel preconditioning on the first-order/second-order pseudo-Newton algorithm (referred in the literature as the defect-correction iteration) is also analysed. Implicit methods for steady flow resolution and for accurate unsteady time advancing are proposed and studied. Numerical illustrations involve the natural convection in a square box and a flow around a perforated wall inspired by helicopter engine applications.     

Interstitial fauna in newly‐created floodplain canals of a large regulated river

Artificial drainage canals are often dug in large river floodplains to prevent winter inundation when groundwater level increases. Nothing is known about the biodiversity of the interstitial fauna of these artificial aquatic systems. The water chemistry and interstitial fauna of four drainage canals along the River Rhône (dug 11–15 years ago) were sampled in July during 3 years (1995–1997). A total of 53 taxa were found, with both epigean and hypogean organisms, and some rare phreatobites previously considered as absent from this sector of the Rhône. The faunal assemblage is characterized by limited temporal variations between the 3 successive years. Differences in interstitial fauna composition between the four drainage canals were mostly linked to oxygen availability and to heterogeneity in water origin (true ground water or surface water infiltration through embankment). Low oxygen content results in poorly diversified assemblages, which are always dominated by the same small set of species. In contrast, heterogeneity in water origin resulted in elevated faunal diversity. Copyright © 2000 John Wiley & Sons, Ltd.