Spatial analysis of Yersinia pestis and Bartonella vinsonii subsp. berkhoffii seroprevalence in California coyotes (Canis latrans)

Zoonotic transmission of sylvatic plague caused by Yersinia pestis occurs in California, USA. Human infections with various Bartonella species have been reported recently. Coyotes (Canis latrans) are ubiquitous throughout California and can become infected with both bacterial agents, making the species useful for surveillance purposes. This study examined the geographic distribution of 863 coyotes tested for Y. pestis and Bartonella vinsonii subsp. berkhoffii serologic status to gain insight into the natural history of B. vinsonii subsp. berkhoffii and to characterize the spatial distribution of the two agents.

We found 11.7% of specimens positive to Y. pestis and 35.5% positive to B. vinsonii subsp. berkhoffii. The two pathogens had distinct spatial clusters: Y. pestis was more prevalent in eastern portions of the state and B. vinsonii subsp. berkhoffii in coastal regions. Prevalence of Y. pestis increased with increasing elevation, whereas prevalence of B. vinsonii subsp. berkhoffii decreased with increasing elevation. There were differences in the proportions of positive animals on a yearly basis to both pathogens.     

Spider webs are efficient collectors of agrochemical spray

Spiders are important arthropod predators in natural and agricultural environments. This laboratory study aims to determine the uptake of agrochemical spray by orb webs. Orbs of Araneus diadematus were exposed under controlled conditions to sprays of variable pressure, volume, forward speed and droplet size. Using a tracer dye we determined, by photospectrometry, the amount of spray collected under different conditions which enabled us to calculate the exact volume collected by webs. The spraying treatment simulated four different field practices as well as drift to the field edge. In all cases webs were excellent collectors of spray. Regarding the pure area of the threads, they collected one order of magnitude more of the spray than paper strips did. Moreover, webs were especially efficient in collecting small droplets. We conclude that orb webs (and the spiders who ingest them) are severely exposed to agricultural sprays. Furthermore, due to the uptake of drift, even webs in hedgerows and at field margins may receive high levels of pesticides. The risk of exposing these beneficial arthropods to spray might be reduced by better control of droplet size.     

Welcher Rattenköder ist am wirtschaftlichsten?

Ohne Zusammenfassung     

Pathology of sarcocystis neurona in interferon-gamma gene knockout mice

Pathologic changes were studied in 27 interferon-gamma gene knockout mice 34-54 days after being fed graded doses of Sarcocystis neurona sporocysts derived from a naturally infected opossum. The target tissue for S. neurona infection was the central nervous system. Characteristic histopathologic changes present in all mice consisted of an inflammatory infiltrate consisting of mostly neutrophils and macrophages, fewer eosinophils, and rare multinucleated giant cells. Intralesional protozoa and scattered subacute perivascular cuffs were present. Where the infiltrates were extensive, neuropil rarefaction was frequent. Pathologic changes were much more frequent and severe in the caudal portion of the brain, especially in the cerebellum, than in the middle and cranial portions. Changes were present in all spinal cords examined (10 of 10). Lesions were equally distributed in white and gray matter of the brain and spinal cord and their meningeal linings.     

Simulation of Water and Chloride Transport in Field Lysimeters

In a lysimeter study in the field with soil samples of a Fluvisol the transport of chloride was monitored under high frequency irrigation. The results of this investigation were used for verification of two computer models of different complexity. One was a transient state water and solute movement model the other a simplified steady state model. It was demonstrated that both models predicted nearly equally well the chloride concentrations in the drainage water. For many practical situations, the simple model may be all that is needed to predict the downward movement of solutes in field soils.     

Synthesis and acaricidal activity of 4‐pyrimidinyloxy‐ and 4‐pyrimidinylaminoethylphenyl dioxolanes and oxime ethers

Novel types of mitochondrial respiration inhibitors at complex I, with emphasis on acaricidal activity, have been designed and prepared. The synthetic approach to these 4‐pyrimidinylphenyl ethyl ethers and amines with a specific ketal or oxime function in the phenyl side chain is outlined. Bioassays demonstrate their high potential against important spider mites, like Tetranychus urticae and Panonychus ulmi. Structure–activity relationship studies and several biological parameters are discussed. © 2000 Society of Chemical Industry     

Ionic homeostasis and reactive oxygen species control in leaves and xylem sap of two poplars subjected to NaCl stress

We investigated the effects of increasing soil NaCl concentration on intracellular compartmentalization of salt and on the activities of antioxidant enzymes (superoxide dismutase (SOD), ascorbic peroxidase (APX), catalase (CAT) and glutathione reductase (GR)) and their role in the regulation of reactive oxygen species (ROS; O(2)(-*) and H(2)O(2)) in leaves and xylem sap of salt-tolerant Populus euphratica Oliv. and salt-sensitive P. popularis cv. 35-44. Mesophyll cells of P. euphratica exhibited a high capacity for NaCl exclusion and compartmentalization of salt in vacuoles compared with P. popularis. In P. popularis, the salt treatment resulted in large accumulations of Na(+) and Cl(-) in leaves that induced significant increases in O(2)(-*) and H(2)O(2) production despite marked increases in the activities of antioxidant enzymes in leaves and xylem sap. Separation of the isoforms of leaf SOD, APX and CAT by polyacrylamide gel electrophoresis followed by in-gel activity staining revealed that the salt-induced activities of APX and CAT were the result of increases in activities of all the isoenzymes. Leaf injury and shedding of aged leaves occurred following the oxidative burst in P. popularis, indicating that the increased activities of antioxidant enzymes in P. popularis were insufficient to counter the harmful effects of ROS at high soil NaCl concentrations. Unlike P. popularis plants, P. euphratica plants did not exhibit an oxidative burst in response to the NaCl treatments, because of (1) a high salt exclusion capacity and effective compartmentalization of salt in vacuoles, and (2) up-regulation of antioxidant enzymatic activities after the onset of salt stress. We conclude that P. euphratica plants subjected to saline conditions control ROS homeostasis through two pathways: (1) by maintaining cellular ionic homeostasis and thereby limiting the NaCl-induced enhancement of ROS production under long-term saline conditions; and (2) by rapidly up-regulating antioxidant defenses to prevent oxidative damage.