Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and huanglongbing disease do not exist in the Stapleton Station area of the Northern Territory of Australia

Abstract  A series of specimens of the Asian citrus psyllid, Diaphorina citri , collected from the Northern Territory (NT) in 1915 was recently rediscovered in the Natural History Museum, London. Surveys were conducted in 2002 on suitable hosts in the locality of the 1915 collections to see if the infestation had persisted. These failed to detect either D. citri or the bacterium that it transmits and that causes huanglongbing disease in citrus. It is presumed that D. citri was eradicated fortuitously by the removal of all citrus plants above latitude 19°S during an eradication program for citrus canker in the NT from 1916 until 1922.     

Down-regulation of macrophage CD9 expression by interferon-gamma.

CD9, a member of the tetraspanin family is a cell surface marker expressed on myeloid and nonmyeloid as well as on neoplastic cells. The present study has focused on the role of inflammation and macrophage activation in the regulation of CD9 expression. We report that the expression of CD9 on primary cultures of murine peritoneal macrophages was down regulated by Interferon-gamma, IFN-gamma. This down regulation was concentration-dependent and maximal by 48 h. The changes in surface expression were consistent with similar reductions in CD9 protein and message levels by Western and Northern blot analyses. The mechanism by which IFN-gamma decreases CD9 expression appears to be through the Stat1 signaling pathway as Stat1 knockout mice did not demonstrate any reduction in CD9 expression by IFN-gamma treatment. These results represent the first evidence for the down regulation of CD9 expression with macrophage activation.     

Will intra‐specific differences in transpiration efficiency in wheat be maintained in a high CO2 world? A FACE study

This study evaluates whether the target breeding trait of superior leaf level transpiration efficiency is still appropriate under increasing carbon dioxide levels of a future climate using a semi‐arid cropping system as a model. Specifically, we investigated whether physiological traits governing leaf level transpiration efficiency, such as net assimilation rates (A_net), stomatal conductance (g_s) or stomatal sensitivity were affected differently between two Triticum aestivum L. cultivars differing in transpiration efficiency (cv. Drysdale, superior; cv. Hartog, low). Plants were grown under Free Air Carbon dioxide Enrichment (FACE, approximately 550 µmol mol^?1 or ambient CO₂ concentrations (approximately 390 µmol mol^?1). Mean A_net (approximately 15% increase) and g_s (approximately 25% decrease) were less affected by elevated [CO₂] than previously found in FACE‐grown wheat (approximately 25% increase and approximately 32% decrease, respectively), potentially reflecting growth in a dry‐land cropping system. In contrast to previous FACE studies, analyses of the Ball et al. model revealed an elevated [CO₂] effect on the slope of the linear regression by 12% indicating a decrease in stomatal sensitivity to the combination of [CO₂], photosynthesis rate and humidity. Differences between cultivars indicated greater transpiration efficiency for Drysdale with growth under elevated [CO₂] potentially increasing the response of this trait. This knowledge adds valuable information for crop germplasm improvement for future climates.     

Comparative effects of trichothecene mycotoxins on bovine platelet function: Acetyl T-2 toxin,a more potent inhibitor than T-2 toxin

The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10^?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds.     

Inhibition of cholesteryl ester transfer protein by substituted dithiobisnicotinic acid dimethyl ester: involvement Of a critical cysteine

SC-71952, a substituted analog of dithiobisnicotinic acid dimethyl ester, was identified as a potent inhibitor of cholesteryl ester transfer protein (CETP). When tested in an in vitro assay, the concentration of SC-71952 required for half-maximal inhibition was 1 microm. The potency of SC-71952 was enhanced 200-fold by preincubation of the inhibitor with CETP, and was decreased 50-fold by treatment with dithiothreitol. Analogs of SC-71952 that did not contain a disulfide linkage were less potent, did not display time dependency, and were not affected by dithiothreitol treatment. Kinetic and biochemical characterization of the inhibitory process of CETP by SC-71952 suggested that the inhibitor initially binds rapidly and reversibly to a hydrophobic site on CETP. With time, the bound inhibitor irreversibly inactivates CETP, presumably by reacting with one of the free cysteines of CETP. Liquid chromatography/mass spectroscopy (LC/MS) analyses of tryptic digests of untreated or SC-71952-inactivated CETP was used to identify which cysteine(s) were potentially involved in the time-dependent, irreversible component of inactivation by the inhibitor. One disulfide bond, Cys143-Cys184, was unaffected by treatment with the inhibitor. Inactivation of CETP by SC-71952 correlated with a progressive decrease in the abundance of free Cys-13 and Cys-333. Conversion of Cys-13 to alanine had no effect on the rapid reversible component of inactivation by SC-71952. However, it abolished the time-dependent enhancement in potency seen with the inhibitor when using wild-type CETP. These data indicate that Cys-13 is critical for the irreversible inactivation of CETP by SC-71952 and provides support for the structural model that places Cys-13 near the neutral lipid-binding site of CETP.     

A direct observation of bacterial coverage and biofilm formation by Acidithiobacillus ferrooxidans on chalcopyrite and pyrite surfaces

To obtain a fundamental understanding of the population behaviour of Acidithiobacillus ferrooxidans at chalcopyrite and pyrite surfaces, the early stage attachment behaviour and biofilm formation by this bacterium on chalcopyrite (CuFeS₂) and pyrite (FeS₂) were studied by optical microscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and electron backscatter diffraction (EBSD). The results indicate there was no significant difference in selectivity of bacterial attachment between chalcopyrite and pyrite. However, the result of ToF-SIMS analysis suggests that the surface of the pyrite was covered more extensively by biofilm than that of the chalcopyrite, which may indicate more extracellular polymeric substances (EPS) formation by bacterial cells growing on pyrite. EBSD and optical image analysis indicated that selectivity of bacterial attachment to chalcopyrite was not significantly affected by crystal orientation. The results also suggest that the bacterial population in defective areas of chalcopyrite was significantly higher than on the polished surfaces.