Effect of inoculation and leaf litter amendment on establishment of nodule-forming Frankia populations in soil

High-N(2)-fixing activities of Frankia populations in root nodules on Alnus glutinosa improve growth performance of the host plant. Therefore, the establishment of active, nodule-forming populations of Frankia in soil is desirable. In this study, we inoculated Frankia strains of Alnus host infection groups I, IIIa, and IV into soil already harboring indigenous populations of infection groups (IIIa, IIIb, and IV). Then we amended parts of the inoculated soil with leaf litter of A. glutinosa and kept these parts of soil without host plants for several weeks until they were spiked with [(15)N]NO(3) and planted with seedlings of A. glutinosa. After 4 months of growth, we analyzed plants for growth performance, nodule formation, specific Frankia populations in root nodules, and N(2) fixation rates. The results revealed that introduced Frankia strains incubated in soil for several weeks in the absence of plants remained infective and competitive for nodulation with the indigenous Frankia populations of the soil. Inoculation into and incubation in soil without host plants generally supported subsequent plant growth performance and increased the percentage of nitrogen acquired by the host plants through N(2) fixation from 33% on noninoculated, nonamended soils to 78% on inoculated, amended soils. Introduced Frankia strains representing Alnus host infection groups IIIa and IV competed with indigenous Frankia populations, whereas frankiae of group I were not found in any nodules. When grown in noninoculated, nonamended soil, A. glutinosa plants harbored Frankia populations of only group IIIa in root nodules. This group was reduced to 32% +/- 23% (standard deviation) of the Frankia nodule populations when plants were grown in inoculated, nonamended soil. Under these conditions, the introduced Frankia strain of group IV was established in 51% +/- 20% of the nodules. Leaf litter amendment during the initial incubation in soil without plants promoted nodulation by frankiae of group IV in both inoculated and noninoculated treatments. Grown in inoculated, amended soils, plants had significantly lower numbers of nodules infected by group IIIa (8% +/- 6%) than by group IV (81% +/- 11%). On plants grown in noninoculated, amended soil, the original Frankia root nodule population represented by group IIIa of the noninoculated, nonamended soil was entirely exchanged by a Frankia population belonging to group IV. The quantification of N(2) fixation rates by (15)N dilution revealed that both the indigenous and the inoculated Frankia populations of group IV had a higher specific N(2)-fixing capacity than populations belonging to group IIIa under the conditions applied. These results show that through inoculation or leaf litter amendment, Frankia populations with high specific N(2)-fixing capacities can be established in soils. These populations remain infective on their host plants, successfully compete for nodule formation with other indigenous or inoculated Frankia populations, and thereby increase plant growth performance.     

Glutathione--functions and metabolism in the malarial parasite Plasmodium falciparum

When present as a trophozoite in human erythrocytes, the malarial parasite Plasmodium falciparum exhibits an intense glutathione metabolism. Glutathione plays a role not only in antioxidative defense and in maintaining the reducing environment of the cytosol. Many of the known glutathione-dependent processes are directly related to the specific lifestyle of the parasite. Reduced glutathione (GSH) supports rapid cell growth by providing electrons for deoxyribonucleotide synthesis and it takes part in detoxifying heme, a product of hemoglobin digestion. Free radicals generated in the parasite can be scavenged in reaction sequences involving the thiyl radical GS* as well as the thiolate GS-. As a substrate of glutathione S-transferase, glutathione is conjugated to non-degradable compounds including antimalarial drugs. Furthermore, it is the coenzyme of the glyoxalase system which detoxifies methylglyoxal, a byproduct of the intense glycolysis taking place in the trophozoite. Proteins involved in GSH-dependent processes include glutathione reductase, glutaredoxins, glyoxalase I and II, glutathione S-transferases, and thioredoxins. These proteins, as well as the ATP-dependent enzymes of glutathione synthesis, are studied as factors in the pathophysiology of malaria but also as potential drug targets. Methylene blue, an inhibitor of the structurally known P. falciparum glutathione reductase, appears to be a promising antimalarial medication when given in combination with chloroquine.     

Public Opinions about Overdiagnosis: A National Community Survey

BackgroundDespite evidence about the "modern epidemic" of overdiagnosis, and expanding disease definitions that medicalize more people, data are lacking on public views about these issues. Our objective was to measure public perceptions about overdiagnosis and views about financial ties of panels setting disease definitions.MethodsWe conducted a 15 minute Computer Assisted Telephone Interview with a randomly selected community sample of 500 Australians in January 2014. We iteratively developed and piloted a questionnaire, with a convenience sample (n=20), then with participants recruited by a research company (n=20). Questions included whether respondents had been informed about overdiagnosis; opinions on informing people; and views about financial ties among panels writing disease definitions.FindingsOur sample was generally representative, but included a higher proportion of females and seniors, typical of similar surveys. American Association for Public Opinion Research response rate was 20% and cooperation rate was 44%. Only 10% (95% CI 8%–13%) of people reported ever being told about overdiagnosis by a doctor. 18% (95% CI 11%–28%) of men who reported having prostate cancer screening, and 10% (95% CI 6%–15%) of women who reported having mammography said they were told about overdiagnosis. 93% (95% CI 90%–95%) agreed along with screening benefits, people should be informed about overdiagnosis. On panels setting disease definitions, 78% (95% CI 74%–82%) felt ties to pharmaceutical companies inappropriate, and 91% (95% CI 82%–100%) believed panels should have a minority or no members with ties. Limitations included questionnaire novelty and complexity.ConclusionsA small minority of Australians surveyed, including those reporting being screened for prostate or breast cancer, reported being informed of overdiagnosis; most believed people should be informed; and a majority felt it inappropriate that doctors with ties to pharmaceutical companies write disease definitions. Results suggest strategies to better inform people about overdiagnosis, and review disease definition processes, have significant public sympathy.     

Evolutionary emergence of synaptic nervous systems: what can we learn from the non-synaptic,nerveless Porifera?

Abstract. The Porifera represent one of the only two recent nerveless and muscleless metazoan phyla. Nevertheless, sponges provide behavioral, physiological, pharmacological, morphological, and, more recently, an increasing amount of genetic evidence for a paracrine pre-nervous integration system. Although this system might be derived, it allows us to draw conclusions, on the basis of comparative data, about the origin of the nervous system sensu stricto as found in the eumetazoan phyla. The goal of the present review is to compile recent evidence on the sponge integration systems. Based on this framework, new light is also shed on the evolutionary origin of the eumetazoan synaptic nervous systems, which can be regarded to form an evolutionary biochemical continuum with the paracrine signaling system in sponges. Thus, we can assume that the evolutionary transition from a paracrine-dominated, pre-nervous system to an electrochemically dominated, primordial nervous system resulted in part from compartmentalization effects. As intermediate evolutionary stages, regionalized synapse precursor areas might have occurred within pre-nervous cells, which foreshadowed the highly organized synaptic scaffolds present in recent nerve cells of the Eumetazoa.