Serologic and molecular characterization of tickborne pathogens in lions (Panthera leo) from the Fasano Safari Park, Italy.

Lions (Panthera leo) are an endangered species threatened by illegal hunting, habitat loss, and infectious diseases. Little is known about the tick-borne pathogens that infect lions and could contribute to population declines. The objective of this study was to characterize Rickettsia spp., Anaplasma phagocytophilum, and Coxiella burnetii infections in 10 lions from the Fasano Safari Park in Italy by serology, polymerase chain reaction, and sequence analysis. Although animals did not show clinical signs of tick-borne diseases, evidence of infection with C. burnetii, spotted fever group Rickettsia sp., and A. phagocytophilum were found in 50%, 20%, and 10% of the lions, respectively. One of the lions tested positive for all three pathogens. This study is the first report of molecular evidence of infection with C. burnetii, Rickettsia sp., and A. phagocytophilum in lions and provides evidence that these felids become infected and serve as hosts for tick-transmitted bacteria.     

Evaluation of the API 50CH and API ZYM systems for rapid characterization of Clavibacter michiganensis subsp. sepedonicus, causal agent of potato ring rot

API 50CH and API ZYM systems were used to characterize fifty-three strains of Clavibacter michiganensis subsp. sepedonicus from different geographic locations and several reference strains of the same and different species, including other potato pathogens. Clavibacter michiganensis subsp. sepedonicus strains displayed a high level of homogeneity, both in carbohydrate utilization and in enzymatic activity. Using API 50CH and API ZYM it was possible to differentiate C. michiganensis subsp. sepedonicus strains from the remaining taxa analysed in this study, which included representative strains of the other subspecies of C. michiganensis as well as other bacterial pathogens affecting potatoes. Therefore, these systems could be used as an effective method to characterize C. michiganensis subsp. sepedonicus. Such a procedure would constitute an alternative system to the conventional nutritional and physiological identification tests currently included in the official methods employed in the European Union to detect and identify this bacterium. The results obtained with the API systems agreed with the current taxonomic classification of C. michiganensis, clearly separating sepedonicus from the other subspecies belonging to this species.     

Comparison ofPotato Virus Y andPlum Pox Virus transmission by two aphid species in relation to their probing behavior

Two different aphid species,Myzus persicae (Sulzer) andHyalopterus pruni (Geoffroy) (Homoptera: Aphididae), were used to analyze their ability to transmit two different potyviruses,Potato virus Y (PVY) andPlum pox virus (PPV), to pepper (Capsicum annuum) andNicotiana benthamiana plants, respectively. In parallel experiments,M. persicae consistently transmitted both viruses with high efficiency, whereasH. pruni always failed to transmit either virus. This is in contrast to previous reports describingH. pruni as a vector of these potyviruses. Different aphid probing behavior among individual aphids of each species was obtained in electrical penetration graph (EPG) experiments performed on pepper plants. This suggested thatH. pruni did not transmit these potyviruses due to behavioral differences during probing that impeded virus acquisition and/or inoculation. It was found thatM. persicae usually makes its first probe within the first 2 min, whereasH. pruni individuals remained for more than 10 min on the plant before starting to probe. Furthermore,M. persicae individuals displayed their first intracellular puncture during the first minute of probing whereasH. pruni needed ∼ 15 min to penetrate the cell plasmalemma with their stylets. In addition, intracellular stylet punctures occurred very frequently forM. persicae but was a rare event, never exceeding a single one, forH. pruni. The relevance of these findings for the epidemiological spread of potyviruses by different aphid species is discussed. http://www.phytoparasitica.org posting May 14, 2006.     

Evaluation of cell wall preparations for proteomics: a new procedure for purifying cell walls from Arabidopsis hypocotyls

Background  

The ultimate goal of proteomic analysis of a cell compartment should be the exhaustive identification of resident proteins; excluding proteins from other cell compartments. Reaching such a goal closely depends on the reliability of the isolation procedure for the cell compartment of interest. Plant cell walls possess specific difficulties: (i) the lack of a surrounding membrane may result in the loss of cell wall proteins (CWP) during the isolation procedure, (ii) polysaccharide networks of cellulose, hemicelluloses and pectins form potential traps for contaminants such as intracellular proteins. Several reported procedures to isolate cell walls for proteomic analyses led to the isolation of a high proportion (more than 50%) of predicted intracellular proteins. Since isolated cell walls should hold secreted proteins, one can imagine alternative procedures to prepare cell walls containing a lower proportion of contaminant proteins.     

Response of black rot in cabbage to spatial distribution of inoculum

Disease progress of black rot in cabbage crop was studied over three years in field plots to compare the effects of uni-focal and multi-focal inoculum applied in equal amounts per plot. Disease progress (plant incidence and leaf incidence) was plotted over time, three dimensional maps were made, and disease aggregation was studied by means of geostatistics, black-black counts and Moran's I statistic. Black rot progress was primarily due to focus expansion. Secondary foci may appear at short distances from the initial focus but they usually merge with the expanding initial focus. Anisotropy occurred occasionally but was of minor importance. Disease proceeds faster in plots with multi-focal inoculation than in those with uni-focal inoculation. Probably, serious epidemics in Dutch cabbage fields originate from large numbers of foci.     

Potential errors in measurement of nonuniform sap flow using heat dissipation probes

The empirical calibration of Granier-type heat dissipation sap flow probes that relate temperature difference (DeltaT) to sap velocity (v) was reevaluated in stems of three tropical tree species. The original calibration was confirmed when the entire heated probe was in contact with conducting xylem, but mean v was underestimated when part of the probe was in contact with nonconducting xylem or bark. Analysis of the effects of nonuniform sap velocity profiles on heat dissipation estimates showed that errors increased as v and the proportion of the probe in nonconducting wood increased. If half of a 20-mm probe is in sapwood with a v of 0.15 mm s(-1) and the other half is in nonconducting wood, then mean v for the whole probe can be underestimated by as much as 50%. A correction was developed that can be used if the proportion of the probe in nonconducting wood is known. Even with the entire heated probe in contact with conducting xylem, v would be underestimated when radial velocity gradients are present. In this case, the error would be smaller except when velocity gradients are very steep, as can occur in species with ring-porous wood anatomy. Errors occur because the relationship between DeltaT and v is nonlinear. Mean DeltaT along the probe is therefore not a measure of mean v, and users of heat dissipation probes should not assume that v is integrated along the length of the probe. The same type of error can occur when DeltaT is averaged through time while v is changing, but the error is small unless there are sudden, step changes between zero and high sap velocity. It is recommended that relatively short probes (20 mm or less) be used and that probes longer than the depth of conducting sapwood be avoided. Multiple probes inserted to a range of depths should be used in situations where steep gradients in v are expected. If these conditions are met, heat dissipation probes remain useful and widely applicable for measuring sap flow in woody stems.     

Effect of water stress conditioning on morphology,physiology and field performance of Pinus halepensis Mill. seedlings

Five-month-old Pinus halepensis Mill. seedlings were subjected to 4 irrigation treatments for 8 weeks. After the treatments, morphological and physiologicalattributes assessed included height, diameter, dry weight, water relations parameters, and determination of N, P, K, soluble carbohydrates, and starch concentrations. The remaining seedlings were field planted. Survival and height growth were recorded forfour growing seasons after planting. The mostsignificant effect of irrigation was onmorphology. Increased irrigation lead toseedlings with significantly higher height,root collar diameter and shoot and rootbiomass. Starch and soluble carbohydrateconcentrations were also affected byirrigation. However, parameters derived frompressure-volume curves were not significantlydifferent among treatments, nor were N, P, andK concentrations. There were no differencesamong treatments for survival in the field,which was highly related to summer rainfall. Incomparison, absolute and relative heightgrowth showed some significant but minordifferences among treatments.     

Vegetative propagation of Colutea istria Mill. from leafy stem cuttings

This study investigates the optimal conditions for the vegetative propagation of the multipurpose leguminous shrub Colutea istria from leafy stem cuttings. The conditions examined included 1) the origin of the cutting (apical, medial or basal), 2) indole-3-butyric acid (IBA) treatment (0, 50, 200 or 400 mg/l), 3) the relative humidity of the propagation environment (high or low), 4) wounding base of cutting, and 5) the season in which the cutting was taken. The rooting ability of the cuttings was significantly influenced by all these factors. Winter cuttings obtained from the middle and base of the branch showed a greater rooting capacity than those harvested from the apical area, while autumn cuttings harvested from the middle and apical areas of the branch showed a greater rooting capacity than those harvested from the base. Winter cuttings showed the best rooting capacity than autumn cuttings. IBA treatment (200 mg/l), high humidity (98-100%), and wounding increased the rooting capacity of the cuttings. The sprout of new leaves was higher in basal cuttings, while IBA and wounding also significantly enhanced the root number of rooted cuttings. A method for vegetatively propagating C. istria plants is given.     

Neutralization and buffering capacity of leaves of sugar maple, largetooth aspen, paper birch and balsam fir

We compared the acidity, the external acid neutralizing capacity and the buffering capacity of leaves of four commercially important tree species, largetooth aspen (Populus grandidentata Michx.), sugar maple (Acer saccharum Marsh.), paper birch (Betula papyrifera Marsh.) and balsam fir (Abies balsamea (L.) Mill), at two sites of contrasting soil fertility in southern Quebec. External acid neutralizing capacity (ENC) of leaves was determined by measuring the change in pH induced by soaking fresh leaves in an acidic solution (pH 4.0) for two hours. The ENC was highest for largetooth aspen (14.3 micro equiv H(+) g(-1)), and lowest for sugar maple and balsam fir (< 5 micro equiv H(+) g(-1)). The buffering capacity index (BCI) was determined by measuring the amount of acid necessary to produce a change of 5 micro equiv H(+) in the leaf homogenate. The BCI ranged from 883 micro equiv H(+) g(-1) for largetooth aspen to less than 105 micro equiv H(+) g(-1) for sugar maple and balsam fir. Leaves of sugar maple and balsam fir had a lower internal pH and a higher percentage of ENC over BCI than paper birch and largetooth aspen. Overall, ENC was correlated with the concentration of all leaf nutrients except Ca, and BCI was correlated with Mg, N and Ca. The site effect was relatively unimportant for all variables.