CD36 and Fyn Kinase Mediate Malaria-Induced Lung Endothelial Barrier Dysfunction in Mice Infected with Plasmodium berghei

Severe malaria can trigger acute lung injury characterized by pulmonary edema resulting from increased endothelial permeability. However, the mechanism through which lung fluid conductance is altered during malaria remains unclear. To define the role that the scavenger receptor CD36 may play in mediating this response, C57BL/6J (WT) and CD36−/− mice were infected with P. berghei ANKA and monitored for changes in pulmonary endothelial barrier function employing an isolated perfused lung system. WT lungs demonstrated a >10-fold increase in two measures of paracellular fluid conductance and a decrease in the albumin reflection coefficient (σ_alb) compared to control lungs indicating a loss of barrier function. In contrast, malaria-infected CD36−/− mice had near normal fluid conductance but a similar reduction in σ_alb. In WT mice, lung sequestered iRBCs demonstrated production of reactive oxygen species (ROS). To determine whether knockout of CD36 could protect against ROS-induced endothelial barrier dysfunction, mouse lung microvascular endothelial monolayers (MLMVEC) from WT and CD36−/− mice were exposed to H₂O₂. Unlike WT monolayers, which showed dose-dependent decreases in transendothelial electrical resistance (TER) from H₂O₂ indicating loss of barrier function, CD36−/− MLMVEC demonstrated dose-dependent increases in TER. The differences between responses in WT and CD36−/− endothelial cells correlated with important differences in the intracellular compartmentalization of the CD36-associated Fyn kinase. Malaria infection increased total lung Fyn levels in CD36−/− lungs compared to WT, but this increase was due to elevated production of the inactive form of Fyn further suggesting a dysregulation of Fyn-mediated signaling. The importance of Fyn in CD36-dependent endothelial signaling was confirmed using in vitro Fyn knockdown as well as Fyn−/− mice, which were also protected from H₂O₂- and malaria-induced lung endothelial leak, respectively. Our results demonstrate that CD36 and Fyn kinase are critical mediators of the increased lung endothelial fluid conductance caused by malaria infection.     

Haematology of the Australian eastern quoll, Dasyurus viverrinus--II. Red cell enzymes and metabolic intermediates

1. The activity of 21 red cell enzymes and three red cell metabolic intermediates were measured in adult Dasyurus viverrinus and compared with published data on other marsupials. 2. Phosphofructokinase (PFK), glyceraldehyde dehydrogenase (GAPD) and phosphoglycerate kinase (PGK) were elevated in comparison to other marsupials. 3. Enolase (ENO) and 2,3-diphosphoglycerate (2,3 DPG) were lower than in other marsupials.     

Uptake of L-dopa and L-5-hydroxytryptophan by endocrine-like cells in the rat larynx

Synopsis In the larynx of the rat, and to a lesser extentin the trachea and main bronchi, there are numerous cells which possess the amine-handling characteristics, but not the enzymatic ones, of the APUD series of endocrine polypeptide cells. The cytochemical properties of their contained granules, which are ultrastructurally atypical in reaching sizes up to 2000 nm on their longest axis, are not those of the APUD series since their protein is predominantly basic and arginine-rich, rather than acidic.A weak formaldehyde-induced autofluorescence is present in the cells, due to a substance with an excitation maximum at 400 nm and an emission maximum at 490 nm. This may be dopamine.The true nature of these endocrine-like cells is not apparent. They are regarded, for the present, as being related to cutaneous melanocytes.     

Demonstration of the neural crest origin of type I (APUD) cells in the avian carotid body,using a cytochemical marker system

Summary The biogenic amines present in the carotid body Type 1 cells of two avian species (Japanese quail and chicken) were identified, by microspectrofluorometry of formaldehyde-induced fluorescence, as dopamine and 5-hydroxytryptamine respectively. These and other cytochemical properties establish the cells as members of the APUD series.Grafts of the neural rhombencephalic primordium from 6 to 10-somite quail embryos were implanted in the appropriate region of chick embryos of the same age. After up to 11 days incubation the carotid bodies of the host were freeze-dried and treated with hot formaldehyde vapour. The carotid body Type 1 cells in the chick host were identified, by the presence of dopamine and the absence of 5-HT, as cells from the quail neural crest.The dopamine phenotype in cells of quail origin thus provides a cytochemical marker which may be used for other allograft experiments. The present work confirms earlier findings, using a biological (nuclear chromatin) marker, which showed the avian carotid body to be of neural crest origin.     

Innovation in anti-herbivore defense systems during neopolypoloidy - the functional consequences of instantaneous speciation

Allopolyploid hybridization instantly merges two differentially adapted genomes into one individual. Allopolyploids are often evolutionarily successful, undergoing adaptive radiations despite the genetic and physiological challenges of merging genomes. We examine a suite of induced herbivore resistance traits in three independent lines of the synthetic allopolyploid Nicotianaxmierata (Nma) and its parent species, N. miersii (Nmi) and N. attenuata (Na), to determine how a complex polygenetic adaptation fares during the early stages of neoallopolyploid formation. All species responded to Manduca sexta oral secretions (OS) with a temporally prolonged jasmonate (JA) burst. In one parent (Na), the JA burst was additionally amplified and associated with the elicitation of direct and indirect defenses. In the other parent (Nmi), OS neither amplified the JA burst nor elicited defense responses, although applied MeJA confirmed the inducibility of the defense responses. All lines of Nma retained enough aspects of Na's JA signaling to recognize OS and to accumulate sufficient direct defenses to impair the growth of Manduca larvae. Most defense-related metabolites were retained in Nma even if inherited from only one parent; however, OS-elicited volatiles, trypsin protease inhibitors (TPIs) and chlorogenic acid were lost in some lines, even though MeJA treatment elicited similar responses in all lines. Herbivore defense systems are flexibly inherited in allopolyploids, causing individuals to diverge over only a few generations; for example, line 1 of Nma could not produce TPIs after OS elicitation, whereas lines 2 and 3 could. This flexible integration of defense signaling systems with a diversity of elicited responses may explain why adaptive radiations are commonly found in allopolyploid lineages.     

An enzymatic fluorescent assay for the quantification of phosphite in a microtiter plate format

A sensitive fluorometric assay for the quantification of phosphite has been developed. The assay uses the enzymatic oxidation of phosphite to phosphate by a recombinant phosphite dehydrogenase with NAD⁺ as cosubstrate to produce the highly fluorescent reaction product resorufin. The optimized assay can be carried out in a 96-well microtiter plate format for high-throughput screening purposes and has a detection limit of 0.25 nmol phosphite. We used the method to quantify phosphite levels in plant tissue extracts and to determine phosphite dehydrogenase activity in transgenic plants. The assay is suitable for other biological or environmental samples. Because phosphite is a widely used fungicide to protect plants from pathogenic oomycetes, the assay provides a cost-effective and easy-to-use method to monitor the fate of phosphite following application.     

Radish introduction affects soil biota and has a positive impact on the growth of a native plant

Introduced plants may out-compete natives by belowground allelopathic effects on soil communities including the symbionts of native plants. We tested for an allelopathic effect of an introduced crucifer, Raphanus sativus, on a common neighboring legume, Lupinus nanus, on the legume’s rhizobium affiliates, and on the broader soil community. In both field observations and a greenhouse experiment, we found that R. sativus decreased the density of nodules on L. nanus roots. However, in the greenhouse experiment, R. sativus soils only decreased the density of small, likely non-beneficial rhizobium nodules. In the same experiment, R. sativus soils decreased fungivorous nematode abundance, though there was no effect of R. sativus introduction on fungal density. In the greenhouse experiment, R. sativus soils had a net positive effect on L. nanus biomass. One explanation of this effect is that R. sativus introduction might alter the mutualistic/parasitic relationship between L. nanus and its rhizobial associates with a net benefit to L. nanus. Our results suggest that introduced brassicas can quickly alter belowground communities, but that the net effect of this on neighboring plants is not necessarily negative.     

Chronic Helicobacter pylori Infection Does Not Significantly Alter the Microbiota of the Murine Stomach

We examined the impact of Helicobacter pylori infection on the murine gastric microbiota by culture and terminal-restriction fragment length polymorphism and found that neither acute nor chronic H. pylori infection substantially affected the gastric microbial composition. Interestingly, the total H. pylori burden detected by real-time PCR was significantly higher than that revealed by viable counts, suggesting that the antigenic load sustaining H. pylori-induced gastritis could be considerably higher than previously believed.