Antagonism of the two-needle pine stem rust fungi Cronartium flaccidum and Peridermium pini by Cladosporium tenuissimum in vitro and in planta

Selected isolates of Cladosporium tenuissimum were tested for their ability to inhibit in vitro aeciospore germination of the two-needle pine stem rusts Cronartium flaccidum and Peridermium pini and to suppress disease development in planta. The antagonistic fungus displayed a number of disease-suppressive mechanisms. Aeciospore germination on water agar slides was reduced at 12, 18, and 24 h when a conidial suspension (1.5 x 10(7) conidia per ml) of the Cladosporium tenuissimum isolates was added. When the aeciospores were incubated in same-strength conidial suspensions for 1, 11, 21, and 31 days, viability was reduced at 20 and 4 degreesC. Light and scanning electron microscopy showed that rust spores were directly parasitized by Cladosporium tenuissimum and that the antagonist had evolved several strategies to breach the spore wail and gain access to the underlying tissues. Penetration occurred with or without appressoria. The hyperparasite exerted a mechanical force to destroy the spore structures (spinules, cell wall) by direct contact, penetrated the aeciospores and subsequently proliferated within them. However, an enzymatic action could also be involved. This was shown by the dissolution of the host tell wall that comes in contact with the mycelium of the mycoparasite, by the lack of indentation in the host wall at the contact site, and by the minimal swelling at the infecting hyphal tip. Culture filtrates of the hyperparasite inhibited germination of rust propagules. A compound purified from the filtrates was characterized by chemical and spectroscopic analysis as cladosporol, a known beta -1,3-glucan biosynthesis inhibitor. Conidia of Cladosporium tenuissimum reduced rust development on new infected pine seedlings over 2 years under greenhouse conditions. Because the fungus is an aggressive mycoparasite, produces fungicidal metabolites, and can survive and multiply in forest ecosystems without rusts, it seems a promising agent for the biological control of pine stem rusts in Europe.

Testicular myxosporidiasis in anurans, with a description of Myxobolus fallax n. sp.

During studies of amphibian sperm cryopreservation, a new species of myxosporidean parasite (Myxozoa, Myxosporae) was observed in the testes of the Australian dwarf green tree frog Litoria fallax (Peters). Myxosporidiasis was found to have no affect on L. fallax body condition or sperm numbers. Myxobolus spores from L. fallax are morphologically distinct from Myxobolus hylae spores (infecting the sympatric Litoria aurea Lesson) and the three previously named (exotic to Australia) Myxobolus species found in anurans. Myxobolus fallax n. sp. is characterised by: pseudocyst white, spherical to ovoid, 141 x74 to 438 x337 mum in diameter (mature); plasmodium with spores loosely arranged within interior. Spores ovoid 13.4 +/- 0.5 (12.6-14.6) mum length, 9.5 +/- 0.4 (8.3-10.6) mum width, 6.8 +/- 0.4 (6.5-7.6) mum depth, 1.4 +/- 0.1 (1.3-1.6) length/width; polar capsules broadly pyriform and equal in size 4.2 +/- 0.3 (3.3-4.7) mum length, 2.4 +/- 0.2 (2.1-2.8) mum width; filament coils 7-8, wound tightly and perpendicular to the longitudinal axis of the capsule; polar filament 34 +/- 7.0 (18-50) mum length; intercapsular appendix and sutural ridge folds absent; and iodinophilous vacuole and mucous envelope lacking. In addition to this new species, data from archival samples of M. hylae are provided which show two morphologically distinct spore types. Both appeared rarely in the same pseudocysts and we cautiously retain the single species.

Stratigraphic and palaeoenvironmental significance of a Pennsylvanian (Upper Carboniferous) palynoflora from the PiauFormation, Parnaba Basin, northeastern Brazil

A well-preserved palynoflora is reported from within a cored interval of a coal-exploratory borehole (1-UN-23-PI of the Geological Survey of Brazil) in the southern part of the Parnaiba Basin, northeastern Brazil. The sample studied is from the lower portion of the Piaui Formation. Its palynoflora is characterized by particular abundance of the trilete cavate/pseudosaccate miospores Spelaeotriletes triangulus Neves and Owens, 1966 and S. arenaceus Neves and Owens, 1966, together with cingulizonate forms mainly attributable to Vallatisporites Hacquebard, 1957 and Cristatisporites R. Potonie and Kremp emend. Butterworth et al., 1964. Radially and bilaterally symmetrical monosaccate pollen grains are also well-represented, chiefly by Plicatipollenites Lele, 1964 and Potonieisporites Bhardwaj, 1954, respectively. Taeniate grains (i.e., monosaccates and bisaccates) are relatively minor constituents of the palynoflora; no marine microplankton were encountered. Several species are described in detail : the trilete apiculate spores Brevitriletes levis (Balme and Hennelly) Bharadwaj and Srivastava, 1969 and Horriditriletes uruguaiensis (Marques-Toigo) Archangelsky and Gamerro, 1979; and the taeniate pollen grains Meristocorpus ostentus sp. nov. and Lahirites segmentatus sp. nov. A Pennsylvanian (Late Carboniferous : late Westphalian) age is adduced for the palynoflora via its correlation with part of the Tapajos Group (specifically, the upper Itaituba Formation) of the Amazonas Basin in northern Brazil. The entirely land-derived palynomorphs, associated with abundant plant debris, corroborate previous suggestions that the lower part of the Piaui Formation accumulated in a nonmarine setting under conditions of aridity.

Permian Palynofloral Assemblages of the Chaco-Paraná Basin (Argentina): Systematics and Stratigraphic Significance

Core samples from an upper Palaeozoic, partly glaciogene borehole section (Ordóñez: YPF Cd O es-1) in the southern Chaco-Paraná Basin (Córdoba Province, northeastern Argentina) have produced variable palynological results. Samples from the lower part of the section (i.e., from the diamictite-bearing upper Ordóñez Formation) proved non-palyniferous. Those from the overlying, essentially post-glacial Victoriano Rodríguez Formation yielded spore-pollen assemblages in varying concentrations and in good to excellent states of preservation, thus providing the material basis for the present account. The palynomorph taxa represented in the assemblages comprise 20 species of spores (distributed among 14 genera) and 25 species of pollen grains (14 genera). The majority of the species are described in systematic detail. One trilete spore species -Convolutispora archangelskyi- is newly proposed. Several other, possibly new species (three of trilete spores, one of monosaccate pollen) are represented insufficiently for other than informal naming. The following new combinations, also of trilete spore species, are instituted: Converrucosisporites confluens (Archangelsky & Gamerro, 1979), C. micronodosus (Balme & Hennelly, 1956), and Anapiculatisporites tereteangulatus (Balme & Hennelly, 1956). Sculptural intergradation (granulate through verrucate) among three species -Granulatisporites austroamericanus Archangelsky & Gamerro, 1979, C. confluens, and C. micronodosus- prompts their informal grouping, proposed herein, as the Converrucosisporites confluens Morphon, which is also recognizable elsewhere in the Gondwanan Permian. The possibility, if not the likelihood, that G. austroamericanus is conspecific with Microbaculispora tentula Tiwari, 1965 is canvassed. The palynologically productive borehole section of the Victoriano Rodríguez Formation studied here is assignable to the middle to upper Cristatisporites Zone and to the succeeding Striatites Zone, thus signifying an Early Permian age for this section and facilitating correlation with strata of the Paraná and Paganzo Basins. From this and prior work, the Ordóñez well sequence embracing the Ordóñez and Victoriano Rodríguez Formations includes, in addition to the latter two zones, the preceding (late Pennsylvanian) Potonieisporites-Lundbladispora Zone which is known from the lower to mid-upper part of the Ordóñez Formation. Thus, the Carboniferous-Permian boundary can be inferred to lie within the upper part of the latter formation

Microsporidiosis in a Gouldian finch (Erythrura [Chloebia] gouldiae)

A 12-day-old nestling Gouldian finch (Erythrura [Chloebia] gouldiae) was presented for investigation of a mortality problem in nestling finches raised by Bengalese finch foster parents. On histological examination, large numbers of spores consistent with a microsporidian organism were present within the small intestinal mucosa. Electron microscopy and molecular studies (sequencing the 5' end of the ssu rRNA gene) further defined the organism as Encephalitozoon hellem. Sequence homology with other eukaryotes was determined using a BLASTN search from the NCBI GenBank database. The finch isolate sequences showed greater than 99% homology with those of previously reported human and avian isolates.

Alternative technologies for producing sterile low acid food products

Four emerging high-energy non-thermal technologies may replace or augment heating for producing sterile low-acid food products. High pressure, high-voltage pulsed electric field, high-energy ultrasound and high-intensity pulsed light are all capable of reducing bacterial spore counts under certain conditions. However, only non-continuous high pressure treatments, at temperatures higher than ambient, are currently capable of completely inactivating spores and producing sterile food products. The first three technologies also reduce the resistance of spores to inactivation by heat.

Bracken (Pteridium aquilinum)-induced DNA adducts in mouse tissues are different from the adduct induced by the activated form of the bracken carcinogen ptaquiloside

Following treatment with bracken fern (Pteridium aquilinum) extract and bracken spores a number of DNA adducts were detected by P-32-postlabeling. Three of these adducts have been described previously (Povey et al., Br. J. Cancer (1996) 74, 1342-1348) and in this study, using a slightly different protocol, four new adducts, with higher chromatographic mobility, were detected at levels ranging from 50 to 230% of those previously described, When DNA was treated in vitro with activated ptaquiloside (APT) and analysed by butanol extraction or nuclease P1 treatment, only one adduct was detected by P-32-postlabeling, This adduct was not present in the DNA from mice treated with bracken fern or spores, suggesting either that bracken contains genotoxins other than ptaquiloside or that the metabolism of ptaquiloside produces genotoxins not reflected by activated ptaquiloside. However, as the ATP-derived adduct has been detected previously in ileal DNA of bracken-fed calves, species-specific differences in the metabolism of bracken genotoxins may exist, thereby leading to differences in their biological outcomes. (C) 2001 Academic Press.

Combining nonthermal technologies to control foodborne microorganisms

Novel nonthermal processes, such as high hydrostatic pressure (HHP), pulsed electric fields (PEFs), ionizing radiation and ultrasonication, are able to inactivate microorganisms at ambient or sublethal temperatures. Many of these processes require very high treatment intensities, however, to achieve adequate microbial destruction in low-acid foods. Combining nonthermal processes with conventional preservation methods enhances their antimicrobial effect so that lower process intensities can be used. Combining two or more nonthermal processes can also enhance microbial inactivation and allow the use of lower individual treatment intensities. For conventional preservation treatments, optimal microbial control is achieved through the hurdle concept, with synergistic effects resulting from different components of the microbial cell being targeted simultaneously. The mechanisms of inactivation by nonthermal processes are still unclear; thus, the bases of synergistic combinations remain speculative. This paper reviews literature on the antimicrobial efficiencies of nonthermal processes combined with conventional and novel nonthermal technologies. Where possible, the proposed mechanisms of synergy is mentioned. (C) 2003 Elsevier Science B.V. All rights reserved.

Extratos vegetais e Bacillus thuringiensis visando o manejo de Duponchelia fovealis Zeller (Lepidoptera: Crambidae)

A lagarta Duponchelia fovealis Zeller (Lepidoptera: Crambidae) foi relatada em plantios comerciais do morangueiro no estado do Espírito Santo ocasionando grandes problemas à cultura. Porém, por ser uma praga recente, não há registro de produtos para o seu controle. A cada dia aumenta a demanda por alimentos e outros produtos livres de resíduos, além da necessidade de uma agricultura mais desenvolvida e sustentável. Pesquisas com agentes de controle biológico e extratos vegetais surgem como alternativa para o manejo desse inseto-praga. Este trabalho teve como objetivo avaliar a eficiência de formulados comerciais à base de Bacillus thuringiensis e a atividade do uso dos extratos aquosos de alho e fumo, visando sua adoção como métodos alternativos de controle de D. fovealis. Nos bioensaios para avaliar a patogenicidade e virulência de duas formulações comerciais à base de B. thuringiensis, Agree® e Dipel WP®, sobre a dieta artificial adaptada à base de farelo de soja, germe de trigo e açúcar, proposta por King e Hartley (1985) para Diatraea saccharalis (Lepidoptera: Crambidae), foram inoculados 70 μL de cada formulado comercial, na concentração 1 x 108 esporos·mL-1. Em seguida, avaliou-se a virulência dos respectivos formulados, isso através da estimativa da concentração letal (CL50) para o estádio de maior suscetibilidade. Em virtude dos resultados encontrados, observou-se que o estágio 1 de desenvolvimento apresentou 95,88% e 86,76% de mortalidades para os produtos Agree® e Dipel WP®, respectivamente, demonstrando patogenicidade e virulência à D. fovealis. No bioensaio para avaliar a atividade dos extratos aquosos de alho e fumo, estes foram aplicados na concentração 10% (m/v). Todos os tratamentos foram pulverizados com Torre de Potter, calibrada a pressão de 15 lb/pol². Posteriormente estimou-se a concentração letal (CL50) do extrato aquoso de fumo, o qual apresentou 95% de mortalidade no teste de suscetibilidade. Desta forma, com os resultados obtidos na presente pesquisa, concluiu-se que a utilização de formulados comerciais à base de B. thuringiensis e extrato de fumo podem ser uma alternativa no manejo fitossanitário de D. fovealis.

Exposure to dust in poultry: the importance of task differences for detailed exposure assessment

Dust is a complex mixture of particles of organic and inorganic origin and different gases absorbed in aerosol droplets. In a poultry unit include dried faecal matter and urine, skin flakes, ammonia, carbon dioxide, pollens, feed and litter particles, feathers, grain mites, fungi spores, bacteria, viruses and their constituents. Dust particles vary in size and differentiation between particle size fractions is important in health studies in order to quantify penetration within the respiratory system. A descriptive study was developed in order to assess exposure to particles in a poultry unit during different operations, namely routine examination and floor turn over. Direct-reading equipment was used (Lighthouse, model 3016 IAQ). Particle measurement was performed in 5 different sizes (PM0.5; PM1.0; PM2.5; PM5.0; PM10). The chemical composition of poultry litter was also determined by neutron activation analysis. Normally, the litter of poultry pavilions is turned over weekly and it was during this operation that the higher exposure of particles was observed. In all the tasks considered PM5.0 and PM10.0 were the sizes with higher concentrations values. PM10 is what turns out to have higher values and PM0.5 the lowest values. The chemical element with the highest concentration was Mg (5.7E6 mg.kg-1), followed by K (1.5E4 mg.kg-1), Ca (4.8E3 mg.kg-1), Na (1.7E3 mg.kg-1), Fe (2.1E2 mg.kg-1) and Zn (4.2E1 mg.kg-1). This high presence of particles in the respirable range (<5–7μm) means that poultry dust particles can penetrate into the gas exchange region of the lung. Larger particles (PM10) present a range of concentrations from 5.3E5 and 3.0E6 mg/m3.

Occupational exposure to Aspergillus by swine and poultry farm workers in Portugal

Aspergillus is among a growing list of allergens that aggravate asthmatic responses. Significant pulmonary pathology is associated with Aspergillus-induced allergic and asthmatic lung disease. Environments with high levels of exposure to fungi are found in animal production facilities such as for swine and poultry, and farmers working with these are at increased risk for occupational respiratory diseases. Seven Portuguese poultry and seven swine farms were analyzed in order to estimate the prevalence, amount, and distribution of Aspergillus species, as well as to determine the presence of clinical symptoms associated with asthma and other allergy diseases in these highly contaminated settings. From the collected fungal isolates (699), an average incidence of 22% Aspergillus was detected in poultry farms, while the prevalence at swine farms was 14%. The most frequently isolated Aspergillus species were A. versicolor, A. flavus, and A. fumigatus. In poultry farms, A. flavus presented the highest level of airborne spores (>2000 CFU/m3), whereas in swine farms the highest was A. versicolor, with an incidence fourfold greater higher than the other mentioned species. Eighty workers in these settings were analyzed, ranging in age from 17 to 93 yr. The potentially hazardous exposure of poultry workers to mold allergens using sensitization markers was evaluated. Although no significant positive association was found between fungal contamination and sensitization to fungal antigens, a high incidence of respiratory symptoms in professionals without asthma was observed, namely, wheezing associated with dyspnea (23.8%) and dyspnea after strenuous activities (12.3%), suggesting underdiagnosed respiratory disturbances. Further, 32.5% of all exposed workers noted an improvement of respiratory ability during resting and holidays. From all the analyzed workers, seven were previously diagnosed with asthma and four reported the first attack after the age of 40 yr, which may be associated with their occupational exposure. Some of the fungi, namely, the Aspergillus species detected in this study, are known to induce hypersensitivity reactions in humans. This study confirmed the presence and distribution of Aspergillus in Portuguese poultry and swine farms, suggesting a possible occupational health problem and raising the need for preventive and protective measures to apply to avoid exposure in both occupational settings.

Possible respiratory infection due to Aspergillus in workers from swineries and poultries

Recent epidemiologic studies clearly outline the link between fungal sensibilization and exarcebations of asthma, leading to increased morbidity and mortality. Amongst the filamentous fungi, Aspergillus scpecies have been strongly linked with exarcebations of asthma and other respiratory allergic diseases. Particles of approximately 1 to 4 pm are deposited in the lower respiratory tract. Therefore, conidia of A. fumigatus are small enough to traverse the terminal respiratory airways and reach the pulmonary alveoli, whereas the larger conidia of some other Aspergillus species, such as A. flavus and A. niger, tend to be deposited in the paranasal sinuses and upper airways. Exposute to environmental fungal spores has been associated with worsening asthma symptoms, lung function, hospital admissions and asthma-related deaths.

Isolamento e caracterização de uma proteína tóxica produzida por um isolado açoriano de Bacillus weihenstephanensis

Dissertação de Mestrado, Biotecnologia em Controlo Biológico, 27 de Junho de 2013, Universidade dos Açores.