Preferential accumulation of severe variants of Citrus tristeza virus in plants co-inoculated with mild and severe variants

The viral population in sweet orange plants, either healthy or pre-inoculated with the asymptomatic isolate of Citrus tristeza virus (CTV) T32, and then graft- or aphid-inoculated with the stem-pitting isolate T318, was characterized with respect to symptom expression, reaction with monoclonal antibody MCA13, single-strand conformation polymorphism (SSCP) of genes p18 and p20, bi-directional RT-PCR, and dot-blot hybridisation. All plants inoculated with T318, with or without pre-inoculation, showed stem pitting, reacted with MCA13, had the SSCP profile characteristic of this isolate, and in bi-directional RT-PCR yielded a 450-bp DNA product associated with severe isolates, indicating that T32 afforded no protection against T318. The latter isolate had two main sequence variants, the minor one of which was indistinguishable from the main T32 sequence, and both were detected in most plants that were graft-inoculated with T318. However, the T32 variant was not detected in plants that were aphid-inoculated only with T318 and also showed stem pitting. This suggested an association of symptoms with the major T318 sequence and preferential transmission of this variant by aphids. The T318-specific variant accumulated more than the T32 variant in plants in which both were replicating, suggesting a higher fitness of the former. Our results clearly emphasize the potential threat of severe CTV variants in areas where mild isolates are presently predominant.

Synthesis and Evaluation of Adenosine Antagonist Activity of a Series of [1,2,4]Triazolo[1,5-c]quinazolines

A series of [1,2,4]triazolo[1,5-c]quinazolines were prepared in satisfactory yields by reaction of some derivatives of 2-aminobenzohydrazide with several hydrochlorides of aromatic amidines, and their binding affinities for the recombinant human adenosine A2A and A2B receptors were determined. None of the new compounds showed noteworthy affinity for these receptors, though a very high affinity for the A2A receptor and, consequently, a high level of A2A/A2B selectivity was revealed for one of the synthesized compounds.

Oestrogenicity of paper and cardboard extracts used as food containers

Bisphenol-A (BPA), dibutyl phthalate (DBP), and di-2-ethylhexyl phthalate (DEHP), which are common chemical residues in food-packaging materials, were investigated in paper and cardboard containers used for take-away food. The oestrogenicity of aqueous extracts was tested in E-Screen bioassay and analysis carried out by high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC/MS). Oestrogenicity was demonstrated in 90% of extracts (geometric mean [GM] = 11.97 pM oestradiol equivalents g(-1)). DEHP, DBP, and BPA (GM = 341.74, 37.59, and 2.38 ng g(-1) of material) were present in 77.50, 67.50, and 47.50% of samples, respectively. In bivariate analyses, no significant association was found between the levels of these chemicals and oestrogenicity in cardboard/paper extracts. A close-to-significant association was found between oestrogenicity and DBP (beta = 1.25; p = 0.06) in paper extracts, which reached statistical significance in multivariate analysis (beta = 1.61; p = 0.03). Paper and cardboard used in food packaging may contribute to the inadvertent exposure of consumers to endocrine-disrupting chemicals.

Dynamic modeling of an enzymatic membrane reactor for the treatment of xenobiotic compounds

A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane was set up for the enzymatic oxidation of xenobiotic compounds. The azo dye Orange II was selected for the model compound and manganese peroxidase for the oxidative enzyme. The ligninolytic cycle was initiated and maintained by the controlled addition of all factors (reactants, mediators, and stabilizers) at suitable rates. Considering the distinctiveness of this process, in which the substrate to be oxidized is not the primary substrate for the enzyme, a kinetic model was developed. The azo dye concentration and hydrogen peroxide addition rate were found to be the main factors affecting the process. The reaction kinetics was defined using a Michaelis-Menten model with respect to the Orange II concentration and a first-order linear dependence relative to the H(2)O(2) addition rate. The dynamic model, which takes into account both the kinetics and the hydraulics of the system, was validated by comparing the experimental results in continuous operation under steady and non-steady state to model predictions. In particular, the model predicted the behavior of the system when unexpected alterations in steady-state operation occurred. Furthermore, the model allowed us to obtain the most appropriate H(2)O(2)/Orange II ratio in the feed to maximize the process efficiency.

Characterisation of several heterogeneous species of defective RNAs derived from RNA 3 of cucumber mosaic virus

Preparations of double-stranded RNAs (dsRNAs) extracted from Nicotiana tabacum cv Xanthi plants infected with a subgroup IB isolate of Cucumber mosaic virus (CMV) were found to contain a heterogeneous population of defective RNAs (D-RNAs) derived from RNA 3. Characterised D-RNAs ranged in size from 1.5 to 1.9 kb and were derived either by a single in-frame deletion within the 3a or 3b genes or by means of double in-frame deletions within both genes. Also, northern blot hybridisation showed two other types of RNA derived from RNA 3: (a) RNA species of ca. 0.7 kb containing the 3'-terminus but lacking the 5'-terminus, which could be 3'-coterminal subgenomic of D-RNAs derived from the 3b gene and (b) RNA species of unknown origin of ca. 0.8 kb containing the 5'-terminus but lacking the 3'-terminus.

Prevalence of Toxocara cati and other parasites in cats’ faeces collected from the open spaces of public institutions: Buenos Aires, Argentina

Toxocarosis is a worldwide parasitic infection that affects both cats and dogs. Toxocara cati (Schrank, 1788) syn. Toxocara mystax (Zeder, 1800) prevalence was studied in faeces from stray cats collected from the open spaces of public institutions of Buenos Aires city, both building and surrounding open spaces are fenced off. Of the 465 samples obtained from March to June of 2005, 58.3% were found to have parasite eggs. The following parasites were identified from the 271 positive samples: T. cati (61.2%), Cystoisospora spp. (20.3%), Trichuris spp. (17.0%), Toxascaris leonina (15.1%), Ancylostoma spp. (14%) and Aelurostrongylus abstrusus (2.6%). T. cati prevalence was 35.7% (95% confidence interval: 31.2-40.1), with a 42.2% single isolations. The most frequent combination was T. cati and Cystoisospora spp. (9%). More than half the areas studied showed over 40% prevalence. Seventy-one percent of the collected samples were fresh with a variable moist consistency and 29% were older with a dry consistency. A statistically significant association was found between sample consistency and presence of parasites (chi2 = 10.81; p = 0.001) as also between sample consistency and presence of T. cati (chi2 = 11.27; p = 0.0007). Moist consistencies were significantly different from the rest: consistency (wet or dry) versus parasites (z = 1.95; p = 0.02) (95% confidence interval: 0.004-0.203); consistency (wet or dry) versus T. cati (z = 3.25; p = 0.0006) (95% confidence interval: 0.075-0.254). The cat population that inhabits these public green spaces contaminates the environment, thus transforming them into dangerous spaces with a variable rate for the human population that spends time in these places.

Germinoma in razor clam Ensis arcuatus (Jeffreys, 1865) in Galicia (NW Spain)

Germinoma is a gonadal neoplasm originating from progenitor cells in germinal epithelium. Over the last four decades it has been diagnosed in several species of marine bivalve molluscs but most consistently in some populations of Mercenaria mercenaria and Mya arenaria in North America. Tissue sections of gonads from Ensis arcuatus (family Pharidae--superfamily Solenacea), collected in Ría de Vigo (Galicia-NW Spain), revealed germinoma in both males and females. Proliferating, undifferentiated, germ cells, with no evidence of maturation, had formed discrete masses in the walls and lumens of gonadal follicles. This is the first report of germinoma in superfamily Solenacea.

Removal of linear alkylbenzene sulfonates and their degradation intermediates at low temperatures during activated sludge treatment

The degradation of linear alkylbenzene sulfonates and their degradation intermediates (sulfophenylcarboxylic acids) has been characterized at 9 degrees C in an activated sludge pilot plant. After an adequate adaptation period (20 days), LAS primary degradation exceeds 99% and takes place preferentially for long alkyl chain homologues and external isomers. LAS homologues in the reactor are preferentially sorbed onto particulate matter, while sulfophenylcarboxylic acids (SPCs) are present predominantly in solution, due to their lower hydrophobicity. During the adaptation period the most abundant LAS biodegradation intermediates were long chain sulfophenylcarboxylic acids (SPCs) (C(9)-C(13)SPC). However once this system is fully adapted, the microorganisms are capable of degrading SPCs efficiently. SPCs with 7-9 carbon atoms in the carboxylic chain predominate due to their degradation being slower than for the rest of the SPCs. The presence of C(13)SPC confirms that LAS degradation in wastewater starts with a omega-oxidation on the alkylic chain. A preferential degradation of SPC isomers of the types 2phiC(n)SPC to 6phiC(n)SPC was also detected, as shown by the relatively higher SPC concentrations of the remaining ones.

Presence of Marteilia sp. (Paramyxea) in the razor clam Solen marginatus (Pennántt, 1777) in Galicia (NW Spain)

Protistan parasites of the genus Marteilia, phylum Paramyxea, cause the molluscs disease named Marteiliosis. Histological observations and transmission electron microscopy revealed the presence of life cycle stages of a Marteilia sp. in the bivalve mollusc Solen marginatus (Solenidae). Parasites occurred in epithelial cells of the digestive ducts and tubules. Early stages (primary cells) presented one or several nuclei while advances stages formed a complex of cells-within-cells (secondary and tertiary cells) culminating in spores. Refringent bodies were present inside the presporangia. This is the first report of a Marteilia sp. in S. marginatus.

Pheromone antagonism in the European corn borer moth Ostrinia nubilalis

Mixing the sex pheromones of the Mediterranean corn borer, Sesamia nonagrioides, and the European corn borer, Ostrinia nubilalis, results in significantly lower captures of O. nubilalis when compared to traps loaded with its pheromone alone. Rubber septa loaded with a constant concentration of the pheromone of O. nubilalis and different percentages of the S. nonagrioides pheromone (from 1 to 100%) causes dose-dependent antagonism in the field. Electroantennograms of O. nubilalis males showed high antennal responses to its own pheromone components, followed by smaller responses to the major, [(Z)-11-hexadecenyl acetate (Z11-16:Ac)], and two minor components [dodecyl acetate (12:Ac) and (Z)-11-hexadecenal (Z11-16:Ald)] of the S. nonagrioides pheromone. There was almost no response to the S. nonagrioides minor component (Z)-11-hexadecenol (Z11-16:OH). Field tests that used traps baited with the O. nubilalis pheromone plus individual components of S. nonagrioides showed that Z11-16:Ald causes the antagonism. Adding 1% Z11-16:Ald to the pheromone of O. nubilalis reduced oriented flight and pheromone source contact in the wind tunnel by 26% and 83%, respectively, and trap captures in the field by 90%. The other three pheromone components of S. nonagrioides inhibited pheromone source contact but not oriented flight of O. nubilalis males and did not inhibit capture in the field. Cross-adaptation electroantennogram suggests that Z11-16:Ald stimulates a different odor receptor neuron than the pheromone components of O. nubilalis. We conclude that Z11-16:Ald is a potent antagonist of the behavioral response of O. nubilalis.

Prevalences of gastrointestinal parasites in sheep and parasite-control practices in NW Spain

A coprological survey to know the presence of gastro-intestinal nematode parasites infecting sheep was done in Galicia (NW Spain), an area with Atlantic climate where sheep production is replacing cattle due to the Agricultural Community Politics of the European Union. From September 2001 to November 2002, 1710 faecal samples were randomly collected from 49 sheep farms and examined by using the flotation technique to determine the prevalence of gastro-intestinal nematode parasites. The sheep-level prevalence was 100%, and the genera identified were Chabertia, Cooperia, Haemonchus, Nematodirus, Oesophagostomum, Teladorsagia, Trichostrongylus and Trichuris spp. A questionnaire was distributed to the farmers (at the same time as sampling) about parasite-control practices during the year before sampling (2000). Ninety percent (95% CI 81%, 98%) of the farmers said they used antiparasitic drugs occasionally, but none of them asked for a coprological analysis prior to the treatment and the efficacy of the drugs was never evaluated. A higher median EPG was observed in the treated sheep (163) than in the untreated ones (26). Chemotherapy was the only parasite-control practice. Flocks that treated according to the farmer's previous experience had higher median EPG (236) than other flocks (185 following the prescription of their veterinary clinician and 232 based on the commercial agent's counsel). Typically, one benzimidazole-treatment per year was applied in autumn and non-veterinary counsel was used. Sheep treated with imidotiazoles had lower EPG (144) than other drugs (164 for the benzimidazoles and 166 for the macrocyclic lactones). We found a higher median EPG in the sheep receiving two treatments/year (175) than in those treated only once per year (156). These results suggest lack of knowledge about worm-control strategies and anthelmintic use or unwillingness to apply such knowledge.

[The use of calcofluor white for studying Malassezia species by direct microscopy]

Fungi of Malassezia genus are known as normal flora in human beings. However, different pathologies due to Malassezia, have been described. Traditionally, early diagnosis was delayed because of the difficulties in culture isolation of these organisms. The aim of this work, is to evaluate the technique of observation microscopy with calcofluor, for identification of Malassezia in both, clinical samples and isolates. In comparison to traditional method of direct examination with lactophenol-blue, calcofluor method offers an advantage because it turns easier the observation of fungal elements and its budding pattern. This technique contributes then, to identify species of Malassezia. The analysis of clinical specimens with calcofluor followed by observation under fluorescence microscopy is a simple and rapid method for the identification, and contribute therefore to the early diagnosis.

[Standard precautions: are these known? Are they applied?]

A study carried out among postgraduate nurses detected a high degree of confusion regarding standard precautions. This led to the formation of a multidisciplinary group from various sections of the health system to investigate this topic in greater detail. Our study observed a high degree of conceptual confusion and a lack of knowledge about standard precautions and the new recommendations regarding decontamination and hand washing in diverse health collectives. It is worrisome to detect at risk habits in relation to self-protective measures among one-third of those surveyed. Knowledge of standard precautions should be integrated with greater efficiency in the medical study programs as well as in continuing professional development programs for health professionals.

Skin immune responses in cattle after primary and secondary infections with Hypoderma lineatum (Diptera: Oestridae) larvae

Cellular immune responses were examined in the skin of cattle after primary and secondary experimental infections with Hypoderma lineatum larvae. Skin biopsies were taken at 0, 6, 12, 48 and 96 h post-infection (h.p.i.). In primary infected animals the penetration of Hypoderma larvae was characterized by moderate inflammatory responses. The pattern of cellular changes in previously infected animals suggested an allergic or rheumatic process, probably as a consequence of the development of a type III hypersensitivity reaction against the second or successive reinfections. Perivascular infiltration with CD3(+) T lymphocytes was marked in infected groups, but especially in previously infected animals, with a significant increase with respect to uninfected controls at 48 h.p.i. B cells remained close to control values during primary infection, while they increased significantly 12 h.p.i. in reinfected animals. IgG(+) plasma cells were also very abundant during secondary infections, with significant differences from primary infected and uninfected animals from 6 h.p.i. onwards. These results suggest that secondary infections allow cellular responses which may be effective in killing some of the entering larvae, resulting in a degree of resistance.

Natural Occurrence of Viruses in Lycopersicon spp. in Ecuador

The Andean region is home of important genetic diversity for the genus Lycopersicon. A survey of three asymptomatic populations of L. hirsutum, 17 of L. parviflorum, 188 of L. pimpinellifolium, and four cultivated populations of L. esculentum was made in nine departments of Ecuador. Samples were analyzed serologically for Tomato spotted wilt virus (TSWV), Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV), Potato virus Y (PVY), Potato virus X (PVX), Groundnut ringspot virus (GRSV), Tomato chlorosis spot virus (TCSV), and Pepino mosaic virus (PepMV). Samples positive as determined using double-antibody sandwich enzyme-linked immunosorbent assay (absorbance values three times higher than negative controls) were analyzed using reverse transcription-polymerase chain reaction (RT-PCR) with virus-specific primers. L pimpinellifolium was the only species of the four found to be infected with viruses. In the department of Manabí, ToMV was detected in 15 of 16 plants from one population, but only a single plant was infected with PepMV. In this department, PepMV was also detected in a single-plant population that corresponded to a volunteer plant found in the wild and TSWV was detected in another plant. In Esmeraldas and Guayas, two single-plant populations were found infected with PepMV and CMV, respectively. TMV, PVY, PVX, GRSV, and TCSV were not detected in this survey. Specific primers were selected for ToMV (To1/To2, genome coordinates 3498-3518/4902-4922, AJ417701), PepMV (Pe1/Pe2 genome coordinates 5030-5050/5913-5935, AJ606359), CMV (Cm1/Cm2 genome coordinates 541-561/1756-1779, D00356), and TSWV (Ts1/Ts2 genome coordinates 4078-4101/4738-4769, AF208498). Amplicons of the expected size were obtained using RT-PCR and then cloned and sequenced. DNA fragments of ToMV, PepMV, and TSWV showed identities greater than 99% with respective sequences in the GenBank database. The highest identity of the CMV DNA fragment was 92% with an isolate from Indonesia (AB042292). The occurrence of viruses such as CMV, ToMV, and TSWV in coastal Ecuador was not surprising. However, infected plants were not found among the samples collected in the departments of Azuay, Carchí, El Oro, Imbabura, Loja, and Pichincha in eastern Ecuador. L. chilense, L. chmielewskii, L. parviflorum, and L. peruvianum were previously reported as natural hosts of PepMV in central and southern Peru (2), and the virus was also detected in L. esculentum in Chile (1). Our results show that PepMV now occurs in wild L. pimpinellifolium populations along the Pacific coast of the South American continent and that it must have efficient means of transmission, although no specific vectors have as yet been identified for this virus. To our knowledge, this is the first report of PepMV in Ecuador and L. pimpinellifolium as a natural host of PepMV. References: (1) M. Muñoz et al. Fitopatología 37:67, 2002. (2) S. Soler et al. J. Phytopathol. 150:49, 2002.