Threat of Infection and Threat-Avoidance Behavior in the Predator <Emphasis Type=Italic>Dicyphus hesperus</Emphasis> Feeding on Whitefly Nymphs Infected with an Entomopathogen

The nature and severity of intraguild interactions between predators and entomopathogens will be determined, in part, by a combination of threat of infection, and avoidance of that threat by the predator. We determined the threat of infection posed by the entomopathogen, Paecilomyces fumosoroseus (as PFR-97™) to the generalist predator, Dicyphus hesperus. We then asked if D. hesperus displays behavioral avoidance of infection while foraging for whitefly nymphs at different stages of infection by the pathogen. When exposed to leaf surfaces treated with the pathogen, 28% of adult female predators died due to infection. Consumption of Ephestia kuehniella eggs by surviving predators over 6 d was significantly reduced, suggesting effects of a sublethal infection. Whitefly nymphs that had been treated with P. fumosoroseus 3 d prior were acceptable as prey to D. hesperus but whitefly nymphs that had been treated with P. fumosoroseus 5 days prior were not. When foraging for whitefly nymphs, adult D. hesperus females rejected infected nymphs 96% of the time, compared to 39% of non-infected nymphs. Paecilomyces fumosoroseus therefore presents a measurable threat to D. hesperus through mortality and reduced prey consumption. Dicyphus hesperus does not avoid initial contact with infected prey but does not feed on such prey. The mechanism underlying these rejections could be due to either avoidance of infection or rejection of prey already consumed by the infectious agent. These results suggest that predation by D. hesperus foraging among infected whitefly nymphs under greenhouse or natural conditions could be reduced through a combination of pathogenicity and reduced efficiency of foraging.     

Human adenoma cells are highly susceptible to the genotoxic action of 4-hydroxy-2-nonenal

Oxidative stress and resulting lipid peroxidation are important risk factors for dietary-associated colon cancer. To get a better understanding of the underlying molecular mechanisms, we need to characterise the risk potential of the key compounds, which cause DNA damage in cancer-relevant genes and especially in human target cells. Here, we investigated the genotoxic effects of 4-hydroxy-2-nonenal (HNE) and hydrogen peroxide (H(2)O(2)) in human colon cells (LT97). LT97 is a recently established cell line from a differentiated microadenoma and represents cells from frequent preneoplastic lesions of the colon. The genomic characterisation of LT97 was performed with 24-colour FISH. Genotoxicity was determined with single cell microgelelectrophoresis (Comet assay). Comet FISH was used to study the sensitivity of TP53-a crucial target gene for the transition of adenoma to carcinoma-towards HNE. Expression of glutathione S-transferases (GST), which deactivates HNE, was determined as GST activity and GSTP1 protein levels. LT97 cells were compared to primary human colon cells and to a differentiated clone of HT29. Karyotyping revealed that the LT97 cell line had a stable karyotype with only two clones, each containing a translocation t(7;17) and one aberrant chromosome 1. The Comet assay experiments showed that both HNE and H(2)O(2) were clearly genotoxic in the different human colon cells. HNE was more genotoxic in LT97 than in HT29clone19A and primary human colon cells. After HNE incubation, TP53 migrated more efficiently into the comet tail than the global DNA, which suggests a higher susceptibility of the TP53 gene to HNE. GST expression was significantly lower in LT97 than in HT29clone19A cells, which could explain the higher genotoxicity of HNE in the colon adenoma cells. In conclusion, the LT97 is a relevant model for studying genotoxicity of colon cancer risk factors since colon adenoma are common preneoplastic lesions occurring in advanced age.     

Structure and regulation of the cAMP-binding domains of Epac2

Cyclic adenosine monophosphate (cAMP) is a universal second messenger that, in eukaryotes, was believed to act only on cAMP-dependent protein kinase A (PKA) and cyclic nucleotide-regulated ion channels. Recently, guanine nucleotide exchange factors specific for the small GTP-binding proteins Rap1 and Rap2 (Epacs) were described, which are also activated directly by cAMP. Here, we have determined the three-dimensional structure of the regulatory domain of Epac2, which consists of two cyclic nucleotide monophosphate (cNMP)-binding domains and one DEP (Dishevelled, Egl, Pleckstrin) domain. This is the first structure of a cNMP-binding domain in the absence of ligand, and comparison with previous structures, sequence alignment and biochemical experiments allow us to delineate a mechanism for cyclic nucleotide-mediated conformational change and activation that is most likely conserved for all cNMP-regulated proteins. We identify a hinge region that couples cAMP binding to a conformational change of the C-terminal regions. Mutations in the hinge of Epac can uncouple cAMP binding from its exchange activity.     

Inhibition of fatty acid amidohydrolase, the enzyme responsible for the metabolism of the endocannabinoid anandamide, by analogues of arachidonoyl-serotonin

Arachidonoyl-serotonin inhibits in a mixed-type manner the metabolism of the endocannabinoid anandamide by the enzyme fatty acid amidohydrolase. In the present study, compounds related to arachidonoyl-serotonin have been synthesised and investigated for their ability to inhibit anandamide hydrolysis by this enzyme in rat brain homogenates. Removal of the 5-hydroxy from the serotonin head group of arachidonoyl-serotonin produced a compound (N-arachidonoyltryptamine) that was a 2.3-fold weaker inhibitor of anandamide hydrolysis, but which also produced its inhibition by a mixed-type manner (Ki(slope) 1.3 microM; Ki(intercept) 44 microM). Replacement of the amide linkage in this compound by an ester group further reduced the potency. In contrast, replacement of the arachidonoyl side chain by a linolenoyl side chain did not affect the observed potency. N-(Fur-3-ylmethyl) arachidonamide (UCM707), N-(fur-3-ylmethyl)linolenamide and N-(fur-3-ylmethyl)oleamide inhibited anandamide hydrolysis with pI50 values of 4.53, 5.36 and 5.25, respectively. The linolenamide derivative was also found to be a mixed-type inhibitor. It is concluded that the 5-hydroxy group of arachidonoyl-serotonin contributes to, but is not essential for, inhibitory potency at fatty acid amidohydrolase.     

Dispersal patterns and chromatic response of Scaphoideus titanus Ball (Homoptera Cicadellidae), vector of the phytoplasma agent of grapevine flavescence dorée

Abstract 1 Scaphoideus titanus Ball, a nearctic leafhopper introduced into Europe in the 1950s, is known to be the vector of the phytoplasma agent of flavescence dorée (FD), a persistent disease of grapevine. Knowledge of its dispersal patterns is thus very important to prevent disease outbreaks. 2 Yellow sticky traps were used to study the seasonal flight activity of S. titanus, its vertical flight, its movement outside the vineyard and the influence of plant density. Sticky traps of different colours (yellow, red, blue, and white) were also compared. The behaviour of males and females was tested for all those conditions. 3 Abundance was greater in normal than in low plant density conditions, and a positive relationship was found between number of plants per square metre and presence of S. titanus. Leafhoppers did not appear capable of spreading significantly outside a vineyard. Few individuals were trapped above the canopy. Red sticky traps caught more individuals than white, yellow or blue, with the latter showing a poor attractiveness. Sex ratio was almost always male biased. 4 Scaphoideus titanus is monophagous and appears incapable of great dispersal away from its host plant, and females are less likely to fly than males. Further studies on the influence of different factors on the behaviour of this leafhopper are suggested.     

Phase Variation of Andrewes in Salmonella enteritidis Bioserotype Paratyphi-A

The natural occurrence of a strain of Salmonella enteritidis bioserotype Paratyphi-A is reported, in which the flagellar antigens segregated readily into normal phase 2 antigens and mixtures of normal phase 1 and phase 2 antigens, and in which phase variation of Andrewes was demonstrated with ease.     

Habitat preference in the critically endangered yellow‐tailed woolly monkey (Lagothrix flavicauda) at La Esperanza,Peru

Habitat loss is one of the main threats to wildlife. Therefore, knowledge of habitat use and preference is essential for the design of conservation strategies and identification of priority sites for the protection of endangered species. The yellow‐tailed woolly monkey (Lagothrix flavicauda Humboldt, 1812), categorized as Critically Endangered on the IUCN Red List, is endemic to montane forests in northern Peru where its habitat is greatly threatened. We assessed how habitat use and preference in L. flavicauda are linked to forest structure and composition. The study took place near La Esperanza, in the Amazonas region, Peru. Our objective was to identify characteristics of habitat most utilized by L. flavicauda to provide information that will be useful for the selection of priority sites for conservation measures. Using presence records collected from May 2013 to February 2014 for one group of L. flavicauda, we classified the study site into three different use zones: low‐use, medium‐use, and high‐use. We assessed forest structure and composition for all use zones using 0.1 ha Gentry vegetation transects. Results show high levels of variation in plant species composition across the three use zones. Plants used as food resources had considerably greater density, dominance, and ecological importance in high‐use zones. High‐use zones presented similar structure to medium‐ and low‐use zones; thus it remains difficult to assess the influence of forest structure on habitat preference. We recommend focusing conservation efforts on areas with a similar floristic composition to the high‐use zones recorded in this study and suggest utilizing key alimentation species for reforestation efforts.     

Successful sexual reproduction of the scleractinian coral Porites panamensis: Evidence of planktonic larvae and recruitment

Porites panamensis is a hermatypic brooder coral endemic to, and distributed along, the Eastern Tropical Pacific, and is considered a species vulnerable to local effects because it has limited capacity for long‐distance dispersal (and low genetic diversity). Although larvae of P. panamensis have been previously shown to recruit to artificial settlement platforms, they have never been observed in the water column. The present study describes the reproductive behavior of P. panamensis, with a focus on using molecular tools to document evidence for a larval planktonic stage and for successful recruitment. Larvae collected from the water column, and recruitment on natural and artificial substrata were documented. Phylogenetic analysis of two ribosomal markers, 18s rRNA and ITS (ITS1‐5.8‐ITS2), and one mitochondrial marker, cytochrome oxidase subunit 1 (cox1), confirmed the taxonomic identity of larvae, and showed that larvae and recruits have genotypes similar to adults of P. panamensis. Lipid vacuoles and Symbiodinium sp. were present in the gastrodermis of all larvae. A total of 12 and 371 recruits settled on artificial and natural substrates, respectively, and the recruitment rate differed significantly over time. By documenting the reproductive success of the species, we show the potential for existing individuals both to maintain the population in the study area and to contribute to maintenance of the coral reef community in the coming decades.     

Shoot regeneration and determination of iridoid levels in the medicinal plant <Emphasis Type="Italic">Castilleja tenuiflora</Emphasis> Benth.

Castilleja tenuiflora is a medicinal plant that grows in pine–oak woods primarily in southern and central Mexico. It is highly valued for its medicinal properties, which have been attributed to aucubin-like iridoids. In the present study, we developed an efficient protocol for in vitro shoot proliferation and ex vitro rooting of C. tenuiflora. Using a colorimetric method, we determined total iridoid contents of various different tissues of propagated plants. The shoots were induced from nodal explants cultured on Murashige and Skoog (MS) (1962) medium supplemented with indole-3-butyric acid (IBA) (0 and 0.5 μM) and different concentrations of thidiazuron (TDZ), 6-benzyladenine (BA), or kinetin (KIN) (0–20 μM). Of the cytokinins tested, KIN was more effective for shoot induction than TDZ or BA, and the highest shoot proliferation rate was achieved with 5 μM KIN (4 shoots per explant). Plantlets were rooted on MS medium, nutrient solution, or potting mix, alone or in combination with auxins. The best responses (100% rooting efficiency) were obtained by dipping shoots in half-strength MS medium containing 7.5 μM IBA before transfer to potting mix. On average, each shoot formed 9 roots of 39.3 ± 3.8 mm in length after 21 days. These roots appeared to be more functional than those that developed in nutrient solution, and were associated with a high survival rate (95%) during acclimatization and cultivation in a greenhouse, where flowering occurred after 4 months. Propagated plants accumulated iridoids, thus representing a potential source of pharmacologically useful compounds.     

Purification and properties of DNA topoisomerase II from Daucus carota cells

Topoisomerase II was partially purified from Daucus carota cellsby a procedure including ammonium sulphate fractionation, ion-exchange,and affinity chromatography steps. The type II enzyme, identifiedfor its ability to unknot knotted P4 DNA and decatenate Trypanosomacruzi kDNA, requires ATP and Mg²⁺ for activity. The unknottingactivity was sensitive to an inhibitor of the mammalian typeII enzyme, the drug VP16 (IC₅₀ 32 mmol m^–3), whereas inhibitorsof DNA gyrase showed a limited effect on activity. The SDS-PAGEanalysis of the dsDNA cellulose fraction revealed the presenceof four polypeptides of apparent molecular masses of 72, 71,34, and 33 kDa among which only a polypeptide of about 70 kDacrossreacted with antibodies against yeast topoisomerase II.Immunoprecipitation experiments with monoclonal antibodies tothe and ß isoforms of the human enzyme confirmedthe recognition of a polypeptide of 70 kDa. The sedimentationcoefficient (S) of the topoisomerase II in the phosphocellulosefraction, calculated by analytical glycerol gradient, was 6.1corresponding to a molecular mass of about 123 kDa. Resultssuggest the presence in carrot of a protein of molecular massof 70 kDa having the typical properties of an eukaryotic topoisomeraseII and carrying epitopes recognized by MoAbs to both human and ß enzymes. The 70 kDa polypeptide might then representthe monomer of a homodimer enzyme of 123 kDa. Key words: Daucus carota, topoisomerase II, immunoprecipitation