Ribonuclease-sensitive ribosomal vaccines

This paper presents an analysis of the protective properties of the components in ribonuclease (RNase)-sensitive ribosomal vaccines, in particular the ribonucleic acid (RNA). The protective activities in mice of purified ribosomes derived fromPseudomonas aeruginosa and fromListeria monocytogenes were compared. Both ribosomal vaccines had to be combined with the adjuvant dimethyldioctadecylammonium bromide (DDA) in order to be protective, and both lost their activity after RNase treatment. The ribosomal vaccines as well as RNA purified from the ribosomes induced non-specific protection. Intraperitoneal injection of RNA with DDA induced an influx of peritoneal cells. Furthermore, RNA with DDA activated macrophages as shown by, a.o., enhanced phagocytic activity and killing capacity forL. monocytogenes. The results suggest that the observed macrophage activation is probably T-cell-independent. With regard to the ribosomal vaccine ofP. aeruginosa it is concluded that RNA also contributed to the protective activity by increasing the humoral response against suboptimal concentrations of contaminating cell surface antigens. In conclusion, it is proposed that ribosomal vaccines may be considered as a combination of a non-specific immunomodulator (RNA) with pathogen-specific cell surface antigens. This concept of ribosomal vaccines is discussed in relation to the literature concerning RNase-sensitive ribosomal vaccines.     

High solar radiation hinders tree regeneration above the alpine treeline in northern Ecuador

Many tropical alpine treelines lie below their climatic potential, because of natural or anthropogenic causes. Forest extension above the treeline depends on the ability of trees to establish in the alpine environment. This ability may be limited by different factors, such as low temperatures, excess solar radiation, competition, soil properties, dispersal ability, and fires. In this paper we address the following two questions: Do trees regenerate above the present treeline, and what are the inhibiting factors for tree establishment? To answer these questions we described the spatial pattern of recent tree establishment below and above the present treeline in northern Ecuador. Also, we experimentally transplanted seedlings into the alpine vegetation (páramo) and the forest, and investigated the effect of shade, neighboring plants, and substrate on their survival. The number of naturally occurring tree sprouts (seedlings, saplings and ramets) was highest just outside the forest, and decreased with distance to the forest edge. However, only two species that were radiation-tolerant made up these high numbers, while other species were rare or absent in the páramo. In the forest, the species diversity of sprouts was high and the abundance per species was relatively low. The transplanted seedlings survived least in experimental plots without artificial shade where neighboring plants were removed. Seedling survival was highest in artificially shaded plots and in the forest. This shade-dependence of most tree species can strongly slow down forest expansion toward the potential climatic treeline. Due to the presence of radiation-tolerant species, the complete lack of forest expansion probably needs to be ascribed to fire. However, our results show that natural processes can also explain both the low position and the abruptness of tropical treelines.     

Male silver eels mature by swimming

Background  

If European silver eels are prevented from reproductive migration, they remain in a prepubertal stage by dopaminergic inhibition of pituitary activity. Because this inhibition is likely a requirement for an extended female growth stage, we tested if it is sex-specific by subjecting both sexes to stimulation by GnRHa (Gonadotropin-Releasing Hormone agonist) – injection or 3-months swimming in seawater.     

A topography-based model of forest cover at the alpine tree line in the tropical Andes

Aim  To present a method that assesses the influence of environmental variables, including climate, substrate, topography, and anthropogenic disturbances, on the distribution of Andean forest at the tree line, and to compare this forest distribution between areas.
Location  Sangay National Park, on the eastern slopes of the Andes in central Ecuador.
Methods  A logistic regression model was built using topographical variables and environmental indices, derived from a digital elevation model, to explain forest cover, derived from a Landsat ETM image, in a zone around the average tree line altitude.
Results  The model shows that after altitude, which can explain about 80% of forest cover, wetness has the next strongest effect (areas accumulating water, but also cold air, were devoid of forest, resulting in inverted tree lines), followed by eastness (western slopes had forest to higher altitudes). Application of the model in two nearby areas showed that the real tree line was lower than the predicted tree line in both areas, probably owing mainly to macroclimatic differences in one area, and partly also to human land use in the other. The locations with the largest deviations could be the focus of further research concerning human impacts on tree line vegetation.
Main conclusions  The tree line is located at lower altitudes on east-facing slopes, which may be because high levels of radiation are received by east-facing slopes in the clear mornings, resulting in the photoinhibition of tree seedlings in the páramo. In spite of the limitations of the quality and resolution of the remote sensing data, the presented method provides indications for important ecological factors at the tree line. The method also allows the detection of differences in tree line position between areas, which may reflect climatic differences or the location of anthropogenic disturbances.     

Some signals cannot wait: Effects of a national campaign on early detection of cancer among Dutch adults (>55 years)

Background: The present study examined the effects of the campaign “early detection of cancer” on knowledge, attitudes, awareness, and intention to perform passive detection and timely seeking medical help. Further, the campaign was evaluated on recall and recognition and the various campaign components were evaluated. Methods: A longitudinal study using a Solomon four-group design among 784 Dutch adults aged 55 years and older was conducted. Data was gathered by means of telephone interviews. Results: The results showed moderate levels of campaign awareness. After the campaign, solely respondents who received a pre-test questionnaire and were aware of the campaign had significant higher cancer knowledge levels regarding passive detection. Respondents who were only aware of the campaign were significantly more willing to perform passive detection behavior and to timely seek medical help in the future. Further, they were more aware that paying attention to cancer warning signs can lead to early detection of cancer. Conclusions: It can be concluded that solely the combination of the pre-test questionnaire and exposure to the campaign had a significant positive impact on respondents’ cancer knowledge levels. The effects of the campaign on intention and awareness are indistinct and could be a consequence of (the results of) a self-selection bias. It seems that the dose, frequency, and duration of the campaign should be increased in order to substantiate the effects of the campaign.     

Swimming suppresses hepatic vitellogenesis in European female silver eels as shown by expression of the estrogen receptor 1, vitellogenin1 and vitellogenin2 in the liver

Background  

When European silver eels (Anguilla anguilla) venture into the Atlantic Ocean for their 6,000 km semelparous spawning run to the Sargasso Sea, they are still in a prepubertal stage. Further sexual development appears to be blocked by dopaminergic inhibition of hypothalamus and pituitary activity. Recently, we found that swimming for several weeks in freshwater stimulated the incorporation of fat droplets in the oocytes. So, it was hypothesized that long term swimming in seawater would release the inhibition further and would also stimulate the production of vitellogenin by the liver.     

Polyinosinic polycytidylic acid prevents efficient antigen expression after mRNA electroporation of clinical grade dendritic cells

Tumor-derived peptides are used frequently as antigen (Ag) source in dendritic cell (DC) therapy in cancer patients. An alternative is to load DC with tumor-associated Ag (TAA)-encoding RNA. RNA-loading obviates prior knowledge of CTL and Th epitopes in the Ag. Multiple epitopes for many HLA alleles (both MHC class I and class II) are encoded by the RNA and loading is independent of the patient’s HLA make-up. Herein, we determined the optimal conditions for mRNA-electroporation of monocyte-derived DC for clinical application in relation to different maturation cocktails. The data demonstrate that TAA carcinoembryonic antigen, gp100 and tyrosinase are expressed already 30 min after electroporation with the encoding mRNA. Moreover, gp100-specific CTL are activated by gp100 mRNA-electroporated DC. Importantly, we show here that the presence of polyinosinic–polycytidylic acid [poly(I:C)] in the maturation cocktail prevents effective protein expression of the electroporated mRNA as well as subsequent CTL recognition. This effect of poly(I:C) correlates with the induction of IFN-induced genes and innate anti-viral effector molecules in DC. Together these data show that electroporation of mature DC with TAA-encoding mRNA is attractive for use in DC vaccination protocols in cancer patients, but protein expression should be tested for each maturation cocktail. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Differential effects of jasmonic acid treatment of Brassica nigra on the attraction of pollinators, parasitoids, and butterflies

Herbivore-induced plant defences influence the behaviour of herbivores as well as that of their natural enemies. Jasmonic acid is one of the key hormones involved in both these direct and indirect induced defences. Jasmonic acid treatment of plants changes the composition of defence chemicals in the plants, induces volatile emission, and increases the production of extrafloral nectar. However, few studies have addressed the potential influence of induced defences on flower nectar chemistry and pollinator behaviour. These have shown that herbivore damage can affect pollination rates and plant fitness. Here, we have investigated the effect of jasmonic acid treatment on floral nectar production and the attraction of pollinators, as well as the effect on the behaviour of an herbivore and its natural enemy. The study system consisted of black mustard plants, Brassica nigra L. (Brassicaceae), pollinators of Brassica nigra (i.e., honeybees and syrphid flies), a specialist herbivore, Pieris rapae L. (Lepidoptera: Pieridae), and a parasitoid wasp that uses Pieris larvae as hosts, Cotesia glomerata L. (Hymenoptera: Braconidae). We show that different trophic levels are differentially affected by jasmonic acid-induced changes. While the herbivore prefers control leaves over jasmonic acid-treated leaves for oviposition, the parasitoid C. glomerata is more attracted to jasmonic acid-treated plants than to control plants. We did not observe differences in pollinator preference, the rates of flower visitation by honeybees and syrphid flies were similar for control and jasmonic acid-treated plants. Plants treated with jasmonic acid secreted less nectar than control plants and the concentrations of glucose and fructose tended to be lower than in nectar from control plants. Jasmonic acid treatment resulted in a lower nectar production than actual feeding damage by P. rapae caterpillars.