Identification of Glycolytic Enzyme Polypeptides on the Two-Dimensional Protein Map of Saccharomyces cerevisiae and Application to the Study of Some Wine Yeasts

Using a modification of the basic two-dimensional polyacrylamide gel electrophoresis technique, the polypeptides of the protein map of Saccharomyces cerevisiae involved in glycolysis were investigated. This study resulted in a reassignment of two of the seven glycolytic enzyme polypeptides previously identified (Ludwig et al., Mol. Cell. Biol. 2:117-126, 1982), those corresponding to phosphoglycerate kinase and to alcohol dehydrogenase. It also resulted in the identification of two additional glycolytic polypeptides, the enolase B monomer and the glyceraldehyde phosphate dehydrogenase B monomer. The glycolytic enzymes polypeptides so identified were investigated in 5 laboratory strains (all S. cerevisiae) and in 11 commerical strains used for wine making (S. cerevisiae and Saccharomyces bayanus). It appeared highly significant that a particular electrophoretic variant of the glyceraldehyde phosphate dehydrogenase B monomer was found only in the wine yeasts. Furthermore, it was strongly suggested that S. cerevisiae and S. bayanus strains are distinguishible on the basis of a different electrophoretic migration of the enolase B monomer.     

Amazon poison frogs (Ranitomeya amazonica) use different phytotelm characteristics to determine their suitability for egg and tadpole deposition

Parents have to assess the multivariate characteristics of their reproductive sites to maximize their reproductive success through offspring performance. In addition, they may provide care to ensure optimal performance of their offspring. In poison frogs it has been identified that ecological characteristics of reproductive sites may underlie transitions in the involvement of parental sexes in care for offspring. To elucidate the ecological factors that may drive these transitions, it is important to understand which characteristics poison frogs use to assess the quality of their reproductive site. We studied the use of small water bodies in leaf axils of bromeliads, phytotelmata, for egg and tadpole deposition by Amazon poison frogs (Ranitomeya amazonica). We compared phytotelm quality characteristics for preferred egg and tadpole deposition sites and used two choice tests with plastic cups to study the causal relationship with tadpole deposition for the identified characteristics. The differences among quality characteristics of deposition sites were largest among bromeliad species, and for egg or tadpole deposition different bromeliad species were preferred. However, males were also selective in the leaf axils within a bromeliad species that they used for egg or tadpole deposition. Eggs were deposited in small, resource limited water bodies that were close to the forest floor. Tadpoles were deposited in leaf axils holding resource-rich phytotelmata with larger water volumes. Preference of detritus containing water over clear water in choice tests confirmed that Amazon poison frogs assess quality of their tadpole deposition sites on food availability. We conclude that preference for large water volume and resource rich phytotelmata plays an important role in determining male involvement in parental care and speculate that distribution of preferred resources may bring about selection on female involvement in parental care.     

Patient admission planning using Approximate Dynamic Programming

Tactical planning in hospitals involves elective patient admission planning and the allocation of hospital resource capacities. We propose a method to develop a tactical resource allocation and patient admission plan that takes stochastic elements into consideration, thereby providing robust plans. Our method is developed in an Approximate Dynamic Programming (ADP) framework and copes with multiple resources, multiple time periods and multiple patient groups with uncertain treatment paths and an uncertain number of arrivals in each time period. As such, the method enables integrated decision making for a network of hospital departments and resources. Computational results indicate that the ADP approach provides an accurate approximation of the value functions, and that it is suitable for large problem instances at hospitals, in which the ADP approach performs significantly better than two other heuristic approaches. Our ADP algorithm is generic, as various cost functions and basis functions can be used in various hospital settings.     

The tandem PDZ domains of syntenin promote cell invasion

Syntenin is a tandem PDZ protein that has recently been shown to be overexpressed in several cancer cells and tissues, and that might play an active role in tumor cell invasion and metastasis. Here we show that overexpression of the tandem PDZ domains of syntenin in non-invasive cells is necessary and sufficient to stimulate these cells to invade a collagen I matrix, and this effect can be regulated by ligand binding to the PDZ domains. Furthermore, we show that syntenin-induced invasion requires signaling through ras, rho and PI3K/MAPK signaling pathways and involves changes in cell-cell adhesion. Inversely, when we used RNA interference to inhibit syntenin expression in different invasive cancer cell lines, we observed a drastically decreased ability of these cells to migrate and invade into collagen type I or Matrigel. RNAi-treated cells also show increased cell aggregation, indicating that syntenin is important for cell-cell adhesion in epithelial cells. Together, these results suggest that downregulation of syntenin by RNA interference could provide a means of inhibiting tumor invasion and possibly metastasis in different cancers, and point to syntenin as a potential cancer biomarker and drug target.     

Inducible nitric-oxide synthase attenuates vasopressin-dependent Ca2+ signaling in rat hepatocytes

Increases in both Ca(2+) and nitric oxide levels are vital for a variety of cellular processes; however, the interaction between these two crucial messengers is not fully understood. Here, we demonstrate that expression of inducible nitric-oxide synthase in hepatocytes, in response to inflammatory mediators, dramatically attenuates Ca(2+) signaling by the inositol 1,4,5-trisphosphate-forming hormone, vasopressin. The inhibitory effects of induction were reversed by nitric oxide inhibitors and mimicked by prolonged cyclic GMP elevation. Induction was without effect on Ca(2+) signals in response to AlF(4)(-) or inositol 1,4,5-trisphosphate, indicating that phospholipase C activation and release of Ca(2+) from inositol 1,4,5-trisphosphate-sensitive Ca(2+) stores were not targets for nitric oxide inhibition. Vasopressin receptor levels, however, were dramatically reduced in induced cultures. Our data provide a possible mechanism for hepatocyte dysfunction during chronic inflammation.     

Broccoli and turnip plants display contrasting responses to belowground induction by Delia radicum infestation and phytohormone applications

Induced responses to insect herbivory are a common phenomenon in the plant kingdom. So far, induced responses have mostly investigated in aerial plant parts. Recently it was found that root herbivore may also elicit both local and systemic responses affecting aboveground herbivores and their natural enemies. Using broccoli (Brassica oleracea subsp. italica L.) and turnip (Brassica rapa subsp. rapa L.), two cultivated brassicaceaous plants differing in their chemistry and morphology, we analysed the local and systemic induced responses triggered by Delia radicum L. damage, JA and SA application. We also assessed whether the root induction treatments affected D. radicum larval performance. Both D. radicum damage and JA induced changes in glucosinolate and sugar content as well as affected D. radicum performance, while SA application did not. Despite the uniform chemical responses, the effect on larval performance on broccoli and turnip plants was very different. On broccoli, JA root treatment reduced herbivore performance, whereas in turnips the same treatment enhanced it. JA- and D. radicum-induced responses followed similar patterns, which suggests that the JA signalling pathway is involved in root-induced responses to larval feeding. Glucosinolate induction cannot fully explain the differences found in the performance of D. radicum on the different species. Changes in other resistance factors might significantly contribute to the induced resistance in these brassicaceaeous species as well.     

Are population differences in plant quality reflected in the preference and performance of two endoparasitoid wasps?

In recent years, increasing attention has been paid in exploring the role of direct plant defence, through the production of allelochemicals, on the performance of parasitoid wasps and their hosts. However, few studies have determined if parasitoids can detect differences in plant quality and thus preferentially attack hosts on which their progeny develop most successfully. In this study we examined the development and preference of two endoparasitoids, Diadegma semiclausum and Cotesia glomerata , developing in larvae of their respective hosts, Plutella xylostella and Pieris brassicae . In turn, these were reared on different wild populations of black mustard Brassica nigra originating in the Netherlands and Sicily (Italy), as well as single cultivated strains of B. nigra and brown mustard, B. juncea . Chemical analyses of foliar glucosinolates and volatile emissions by P. xylostella -damaged plants revealed large differences between B. nigra and B. juncea plants, with smaller differences among the B. nigra populations. The four mustard populations differentially affected development time and body mass of the herbivores and parasitoids. Contrasts among the means revealed significant differences mainly between B. nigra and B. juncea . Both parasitoids, however, preferred to alight on plants in which their progeny developed most successfully. In behavioural bioassays, D. semiclausum did not discriminate among the B. nigra populations and preferred to alight on B. juncea , which was the best plant population for parasitoid development. By contrast, C. glomerata females exhibited the lowest preference for Italian B. nigra populations, on which adult parasitoid size was the smallest. These results reveal that parasitoids can detect even small differences in plant quality presumably through their volatile blends and that plant preference and offspring performance in the two species are 'optimally synchronized'.