High levels of zinc ions induce loss of mitochondrial potential and degradation of antiapoptotic Bcl-2 protein in in vitro cultivated human prostate epithelial cells

Prostate epithelial cells contain the highest levels of zinc among all organs and tissues in the human body. Zinc is accumulated primarily in the mitochondria, where it is responsible for inhibition of mitochondrial aconitase activity, thereby increasing citrate production. The present study was designed to clarify the role of zinc for human prostate epithelial cell growth and apoptosis. Apoptosis of in vitro cultivated human prostate epithelial cells exposed to ZnCl(2) was analyzed by determination of phospholipid membrane asymmetry, nuclear fragmentation, DNA strand breaks, changes of mitochondrial potential and cellular pro/antiapoptotic proteins. Zinc induced apoptosis without involvement of p53 by decreasing mitochondrial transmembrane potential (DeltaPsi(m)) and Bcl-2 protein levels in proliferating epithelial cells. Thus, the high local concentrations of zinc ions in the prostatic lumen seem to be necessary to regulate proliferative activities and to enforce epithelial differentiation processes.     

Specialisation and diversity of multiple trophic groups are promoted by different forest features

While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above‐ and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation.     

Drosophila Dystrophin is required for integrity of the musculature

Duchenne muscular dystrophy is caused by mutations in the dystrophin gene and is characterized by progressive muscle wasting. The highly conserved dystrophin gene encodes a number of protein isoforms. The Dystrophin protein is part of a large protein assembly, the Dystrophin glycoprotein complex, which stabilizes the muscle membrane during contraction and acts as a scaffold for signaling molecules. How the absence of Dystrophin results in the onset of muscular dystrophy remains unclear. Here, we have used transgenic RNA interference to examine the roles of the Drosophila Dystrophin isoforms in muscle. We previously reported that one of the Drosophila Dystrophin orthologs, the DLP2 isoform, is not required to maintain muscle integrity, but plays a role in neuromuscular homeostasis by regulating neurotransmitter release. In this report, we show that reduction of all Dystrophin isoform expression levels in the musculature does not apparently affect myogenesis or muscle attachment, but results in progressive muscle degeneration in larvae and adult flies. We find that a recently identified Dystrophin isoform, Dp117, is expressed in the musculature and is required for muscle integrity. Muscle fibers with reduced levels of Dp117 display disorganized actin-myosin filaments and the cellular hallmarks of necrosis. Our results indicate the existence of at least two possibly separate roles of dystrophin in muscle, maintaining synaptic homeostasis and preserving the structural stability of the muscle.     

Dehydrins in cold-acclimated apices of birch (Betula pubescens Ehrh.): production, localization and potential role in rescuing enzyme function during dehydration

 Dehydrins accumulate in various plant tissues during dehydration. Their physiological role is not well understood, but it is commonly assumed that they assist cells in tolerating dehydration. Since in perennials the ability of the shoot apex to withstand dehydration is pivotal for survival through winter, we investigated if and how dehydrins may be involved. A first step in assessing such a role is the identification of their subcellular location. We therefore mapped the location of dehydrin homologues, abscisic acid-responsive (RAB 16-like) polypeptides, in the apex of birch (Betula pubescens Ehrh.). In non-cold-acclimated plants a single low-abundant RAB 16-member (a 33-kDa polypeptide) was produced, and localized in the cytoplasm only. During cold acclimation two additional members were produced (24 and 30 kDa) and accumulated in nuclei, storage protein bodies and starch-rich amyloplasts. Western blots of proteins isolated from purified starch granules and from protein bodies revealed the presence of the 24-kDa dehydrin. Since starch and protein reserves are gradually consumed during winter, serving cell maintenance, starch- and protein-degrading enzymes must remain locally active. We therefore investigated the hypothesis that dehydrins might create local pools of water in otherwise dehydrated cells, thereby maintaining enzyme function. In agreement with our hypothesis, enzyme assays showed that under conditions of low water activity a partially purified dehydrin fraction was able to improve the activity of α-amylase (EC 3.2.1.1.) relative to fractions from which dehydrin was removed by immunoprecipitation. The results confirm the general belief that dehydrins serve desiccation tolerance, and suggest that a major function is to rescue the metabolic processes that are required for survival and re-growth. Received: 12 September 1998 / Accepted: 19 April 1999     

Competitive ability of the antagonists Ulocladium atrum and Gliocladium roseum at temperatures favourable for Botrytis spp. development

Ulocladium atrum and Gliocladium roseum are fungal antagonists capable of suppressing sporulation of Botrytis spp. on dead plant parts. The effect of temperature (3 to 36 °C) on antagonist conidial germination and mycelial growth was assessed on agar. In addition conidial germination of U. atrum was measured on dead lily leaves. The optimum temperature of both antagonists for both conidial germination and mycelial growth was between 27 and 30 °C. U. atrum was less affected by lower temperatures than G. roseum. At optimum temperature, 50% of conidia of U. atrum and G. roseum germinated within 2.6 and 10.0 hrs, respectively. At low sub-optimal temperatures (6 °C), 50% of conidia germinated within 18 and 96 hours, respectively.In bioassays on dead onion leaves, U. atrum suppressed sporulation of B. cinerea and B. aclada at all temperatures tested (6 to 24 °C) by more than 85%. On dead cyclamen leaves, G. roseum was more efficient than U. atrum at 21 and 24 °C but, in contrast to U. atrum, showed no antagonistic activity at temperatures below 21 °C. On dead hydrangea leaves, U. atrum significantly reduced sporulation of B. cinerea at temperatures as low as 3 and 1 °C. Under Dutch growing conditions, the mean air temperature during leaf wetness periods in onion and lily fields was 15 °C with temperatures only occasionally above 20 °C. In greenhouse crops of cyclamen, the mean temperature during high humidity periods was 17 °C. It is therefore concluded that U. atrum is better adapted than G. roseum to temperatures which occur in the field, in greenhouse crops such as cyclamen, or during cold storage of plant stocks.     

A Peptide of Heparin Cofactor II Inhibits Endotoxin-Mediated Shock and Invasive Pseudomonas aeruginosa Infection

Sepsis and septic shock remain important medical problems with high mortality rates. Today''s treatment is based mainly on using antibiotics to target the bacteria, without addressing the systemic inflammatory response, which is a major contributor to mortality in sepsis. Therefore, novel treatment options are urgently needed to counteract these complex sepsis pathologies. Heparin cofactor II (HCII) has recently been shown to be protective against Gram-negative infections. The antimicrobial effects were mapped to helices A and D of the molecule. Here we show that KYE28, a 28 amino acid long peptide representing helix D of HCII, is antimicrobial against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive Bacillus subtilis and Staphylococcus aureus, as well as the fungus Candida albicans. Moreover, KYE28 binds to LPS and thereby reduces LPS-induced pro-inflammatory responses by decreasing NF-κB/AP-1 activation in vitro. In mouse models of LPS-induced shock, KYE28 significantly enhanced survival by dampening the pro-inflammatory cytokine response. Finally, in an invasive Pseudomonas infection model, the peptide inhibited bacterial growth and reduced the pro-inflammatory response, which lead to a significant reduction of mortality. In summary, the peptide KYE28, by simultaneously targeting bacteria and LPS-induced pro-inflammatory responses represents a novel therapeutic candidate for invasive infections.     

Hexose uptake by Catharanthus roseus cell suspensions is inhibited by a high medium salt content

Summary The uptake of glucose and fructose from the medium by Catharanthus roseus cell suspensions was strongly inhibited by high medium salt concentration, such as found in LS (Linsmaier and Skoog 1965) medium. After inoculation into standard LS nutrient medium with less than 5 mM hexose no uptake occurred, while in low salt medium hexose was completely depleted. At a hexose concentration of 50 mM the uptake rate was higher in low salt medium than in standard medium. The lower rate of uptake at high salt concentration was not the result of a pH or osmotic effect of the salts. Probably the affinity of the hexose carrier is affected by the ion concentration of the medium. The decrease in medium salt concentration during normal batch culture probably will have a considerable effect on hexose uptake.Abbreviations LS Linsmaier and Skoog - S sucrose - N mineral nitrogen - K K₂SO₄ - F fructose     

Compared roles of glucose, galactose and fructose as glycogen precursors during the acute response to insulin in cultured rat foetal hepatocytes

1. The efficiency of the contribution of hexoses to basal- and stimulated-glycogenesis, when studied in cultured 18 day-old rat foetal hepatocytes in the presence of glucose, was as follows: galactose greater than glucose greater than fructose. 2. Glucose deprivation had opposite effects on the contributions of [14C]galactose (decreased) and [14C]fructose (increased) to glycogenesis, which occurred independently of insulin and were reversed by glucose concentrations as low as 30-100 microM. 3. The stimulation of glycogenesis by insulin measured with [14C]glucose (3.2-fold) was superior to that obtained with either [14C]galactose or [14C]fructose (2.7-fold in both cases), which revealed a specific beneficial effect of insulin on glucose contribution.     

Tree diversity is key for promoting the diversity and abundance of forest-associated taxa in Europe

Plant diversity is an important driver of diversity at other trophic levels, suggesting that cascading extinctions could reduce overall biodiversity. Most evidence for positive effects of plant diversity comes from grasslands. Despite the fact that forests are hotspots of biodiversity, the importance of tree diversity, in particular its relative importance compared to other management related factors, in affecting forest-associated taxa is not well known. To address this, we used data from 183 plots, located in different forest types, from Mediterranean to Boreal, and established along a climatic gradient across six European countries (FunDivEUROPE project). We tested the influence of tree diversity, tree functional composition (i.e. functional trait values), forest structure, climate and soil on the diversity and abundance/activity of nine taxa (bats, birds, spiders, microorganisms, earthworms, ungulates, foliar fungal pathogens, defoliating insects and understorey plants) and on their overall diversity and abundance/activity (multidiversity, multiabundance/activity). Tree diversity was a key driver of taxon-level and overall forest-associated biodiversity, along with tree functional composition, forest structure, climate and soil. Both tree species richness and functional diversity (variation in functional trait values) were important. The effects of tree diversity on the abundance/activity of forest-associated taxa were less consistent. Nonetheless, spiders, ungulates and foliar fungal pathogens were all more abundant/active in diverse forests. Tree functional composition and structure were also important drivers of abundance/activity: conifer stands had lower overall multidiversity (although the effect was driven by defoliating insects), while stands with potentially tall trees had lower overall multiabundance/activity. We found more synergies than tradeoffs between diversity and abundance/activity of different taxa, suggesting that forest management can promote high diversity across taxa. Our results clearly show the high value of mixed forest stands for multiple forest-associated taxa and indicate that multiple dimensions of tree diversity (taxonomic and functional) are important.