Isolation of free-living pathogenic amoebae from thermal spas in N.W. Spain

We tested for the presence of free-living amoebae in water from 12 thermal spas in northwest Spain; 8 tested positive. No relationship was observed between temperature, pH or bacterial contamination and either the presence of amoebae or the, number of strains per sample. A total of 13 strains were found: 5 of Vahlkampfia, 2 of Naegleria, 3 of Acanthamoeba and 3 of other genera. Those Naegleria and Acanthamoeba strains which survived at 37 ? were tested for pathogenicity by intracerebral and intranasal inoculation of mice; only 2 strains (both of the species Acanthamoeba polyphaga) caused death.     

Use of Humic Substances and Amino Acids to Enhance Iron Availability for Tomato Plants from Applications of the Chelate FeEDDHA

Two experiments in consecutive years were conducted in a commercial greenhouse located in the Southeast of Spain. The objective was to test if the addition of commercial organic compounds could improve the uptake of iron (Fe) by tomato plants (Lycopersicon esculentum mill.) cv Daniela. A commercial humic substance (HS) and a mix of amino acids (AA) were used as organic compounds in the first year of the experiment, and FeEDDHA (Q) as a source of iron. Both organic compounds improved iron uptake in comparison to a control without the addition of organic materials, especially the humic substance. A similar experiment was conducted the following year, but part of the chelate was progressively substituted by the humic compound. Results showed that the content of iron in the leaves increased with the substitution without any significant losses of yield or fruit quality. Plant nutrition was also improved because of an increase in the level of phosphorus in the leaves and a decrease in foliar sodium levels indicating a reduction in the effects of salinity.     

Interactions between the introduced fungal pathogen Entomophaga maimaiga and indigenous tachinid parasitoids of gypsy moth Lymantria dispar in Bulgaria

Interactions between the gypsy moth, Lymantria dispar L. (Lepidoptera: Erebidae), pathogenic fungus Entomophaga maimaiga, and the tachinid parasitoid (Diptera: Tachinidae) complex in gypsy moth larvae were investigated in Bulgaria, where E. maimaiga was recently released as a biological control agent. Gypsy moth larvae were collected in oak stands where E. maimaiga was originally introduced (nine sites) and in sites where the pathogen has invaded by natural extension of the range (ten sites). In total, 4,375 host larvae were examined and 401 tachinid larvae emerged from parasitized hosts. Host mortality caused by tachinids varied from 0 to 48.5% among sites, with an overall average of 9.2%. Emerging adult tachinid parasitoids included 54 individuals belonging to six species: Compsilura concinnata, Exorista larvarum, Senometopia separata, Senometopia excisa, Drino incospiqua and Zenilia libatrix; the remaining parasitoids (86.5%) died in the pupal stage. E. maimaiga azygospores were observed on puparia surfaces, an indication that the gypsy moth host larvae were infected with the fungus. No azygospores were observed in parasitoid tissues. The high parasitoid mortality may be the result of the competition with E. maimaiga during development in the same host.     

Sampling plans for aphids and their parasitoids in blueberry fields in Argentina

Densities of aphids (Aphis gossypii and A. spiraecola) and mummified aphids at different phenological stages of a blueberry crop were estimated for the purpose of developing sampling plans. Our data set comprised 99 samples taken during the period 2006–2008 in four fields in Buenos Aires Province, Argentina. Estimation of population density based on the proportion of sample units infested by individuals was investigated. We also calculated the minimum number of sample units to estimate the density of individuals on buds and buds + flowers using enumerative sampling. The relative precision of both methods was compared. Moreover, an enumerative sequential sampling protocol was developed. The presence–absence sampling plan gave density estimates with large variances (as measured by confidence intervals and large standard errors). The aggregation of mummies was similar on buds and buds + flowers, so the required number of sample units for density estimates was the same. Relative precision of estimates was much lower for the presence–absence sampling than the enumerative sampling, even at intermediate densities. An enumerative sequential plan would be the most appropriate and useful method in management plans for aphids and mummified aphids in blueberries.     

Effects of Drying Process on the Physicochemical Properties of Nopal Cladodes at Different Maturity Stages

Chemical proximate analysis was done in order to determine the changes of nutritional characteristics of nopal powders from three different maturity stages 50, 100, and 150 days and obtained by three different drying processes: freeze dried, forced air oven, and tunnel. Results indicate that nopal powder obtained by the process of freeze dried retains higher contents of protein, soluble fiber, and fat than the other two processes. Also, freeze dried process had less effect on color hue variable. No changes were observed in insoluble fiber content, chroma and lightness with the three different drying processes. Furthermore, the soluble fibers decreased with the age of nopal while insoluble fibers and ash content shows an opposite trend. In addition, the luminosity and hue values did not show differences among the maturity stages studied. The high content of dietary fibers of nopal pad powder could to be an interesting source of these important components for human diets and also could be used in food, cosmetics and pharmaceutical industry.     

Biological nitrogen fixation in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) by <Superscript>15</Superscript>N isotope-dilution and identification of associated culturable diazotrophs

The nitrogen-fixing capacity of a range of commercial cultivars of maize (Zea mays L.) was evaluated by the ¹⁵N isotope-dilution method. Biological nitrogen fixation (BNF) expressed as percent nitrogen derived from air (Ndfa) ranged from 12 to 33 regardless of nitrogen fertilization. BNF was not affected by mineral nitrogen fertilization except on cultivar Topacio and PAU-871 cultivars. Subsequently, culturable bacterial diazotrophs were isolated from endophytic tissue of maize: seed, root, stem, and leaf. All isolates were able to grow on N-free semisolid medium. Eleven bacteria isolates showed nitrogen-fixing capacity by the reduction of acetylene to ethylene and confirmed by PCR the presence of nifH gene in their genome. Identification of the 11 isolates was performed by bacteriological methods, 16S rRNA gene sequences, and phylogenetic analysis, which indicated that the bacteria isolated were closely related to Pantoea, Pseudomonas, Rhanella, Herbaspirillum, Azospirillum, Rhizobium (Agrobacterium), and Brevundimonas. This study demonstrated that maize cultivars obtain significant nitrogen from BNF, varying by maize cultivar and nitrogen fertilization level. The endophytic diazotrophic bacteria isolated from root, stem, and leaf tissues of maize cultivars may contribute to BNF in these plants.     

Plant communities and soil phytolith assemblages relationship in native grasslands from southeastern Buenos Aires province,Argentina

This study has compared the phytolith production and soil phytolith assemblages of two native grass communities typical in Argentina, namely the monospecific Paspalum quadrifarium community or “pajonal”, and the Stipa-Piptochaetium community or “flechillar”. Five sites – three of which had been unmanaged while other two had been submitted to fire and fire-grazing management activities – were selected for study. The results show that in these sites a) phytolith production of the plant communities differed due to their diverse floristic composition, b) it was possible to define the type of management or the type of community based on soil phytolith assemblages, c) there were differences between plant communities and soil phytolith assemblages. These results suggest that modern phytolith assemblages are composed not only of local and present vegetation but also of extralocal/regional and probably past vegetation. Hypotheses about the probable processes involved in phytolith incorporation to soil have emerged during the investigation.     

Evaluation of a comparative pathogenesis between cancer-associated retinopathy in humans and sudden acquired retinal degeneration syndrome in dogs via diagnostic imaging and western blot analysis

OBJECTIVE: To evaluate dogs with sudden acquired retinal degeneration syndrome (SARDS) for evidence of pituitary gland, adrenal gland, and pulmonary neoplasia and antiretinal antibodies and to evaluate dogs with neoplasia for antiretinal antibodies. ANIMALS: 57 clinically normal dogs, 17 with SARDS, and 53 with neoplasia. PROCEDURE: Thoracic radiography, ultrasonography of adrenal glands, and contrast-enhanced computed tomography of pituitary glands were performed in 15 dogs with SARDS. Western blot analysis was performed on sera of all dogs; recoverin (23 kd) and arrestin (48 kd) retinal antibodies were used as positive controls. RESULTS: Neoplasia was not detected via diagnostic imaging in dogs with SARDS. Western blot analysis revealed bands in all dogs ranging from > 48 to < 23 kd. Prominent bands with equivalent or greater density than 1 or both positive controls at the 1:1,000 dilution, and present at the 1:3,000 dilution, were detected in 28% of clinically normal dogs, 40% of dogs with neoplasia, and 41% of dogs with SARDS. No bands in dogs with SARDS had a consistent location of immune activity, and none were detected at the 23-kd site. The area around the 48-kd site had increased immune activity in all 3 groups. CONCLUSIONS AND CLINICAL RELEVANCE: The etiology of SARDS in dogs does not appear to be similar to cancer-associated retinopathy in humans on the basis of absence of differential antibody activity against retinal proteins. Although dogs with SARDS often have clinical signs compatible with hyperadrenocorticism, neoplasia of the adrenal glands, pituitary gland, or lungs was not detected.     

75 years of breeding pinto bean for resistance to diseases in the United States

Diseases are major production constraints of pinto bean despite 75 years of breeding. The objectives were to (1) assess progress made and (2) discuss future breeding strategies. Bean common mosaic virus (BCMV), anthracnose, rust, white mold, common blight, and halo blight and growth habit, seed weight, and seed coat darkening were evaluated for 52 cultivars released between 1944 and 2001. Sixteen cultivars were resistant to BCMV, 12 to race 53 of rust, five to race 73 of anthracnose, two to halo blight, and none to common blight and white mold. Four were resistant to two and none to three or more diseases. Four had Type I, ten Type II, and others Type III growth habit. Bill Z, Grand Mesa, Montrose, Olathe, Othello, Ouray and Pindak darkened slower in storage. Pintoba had the largest and Cahone smallest seed. An integrated breeding strategy is suggested for simultaneous improvement of resistance to multiple-diseases.