Searching for bioactive compounds from Solanaceae: lethal and sublethal toxicity to Spodoptera frugiperda and untargeted metabolomics approaches

Journal of Pest Science - The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a major pest of maize crops and others row crops on the American continent, and this...     

Formation of carbon particles from a gas phase: Nucleation phenomenon

Highly divided C can be formed by heat treatment of hydrocarbons in absence of O (thermal decomposition) or in its presence (flames). This variety of C, named soot or carbon black, has a considerable polluting effect. Moreover, considering the increasing cost of energy sources, energy loss under the form of unburnt species has to be reduced. To decrease or to suppress soot formation, it is often necessary to know the mechanism of formation and, in particular, the phenomena involved in the nucleation step. The mechanism of soot formation in flames is basically identical in premixed flames and in diffusion flames. However, as the different chemical stages are well separated, from a spatial point of view, in premixed flames, most investigations deal with this type of flame. In the oxidation zone of the flame (blue zone), a part of the hydrocarbon is burnt out while another part undergoes complex reactions leading to polyacetylenes and later to polycyclic hydrocarbons with lateral chains. In the same region, ions are formed by chemiionization. In the zone of formation of C particles (yellow zone), polycyclic hydrocarbons are dehydrogenated and give polyaromatic hydrocarbons; their partial pressure increases until they reach a supersaturation high enough to induce nucleation of liquid microdroplets. The microdroplets are formed by homogeneous nucleation as well, probably, as the nucleation on the positive ions formed in the oxidation zone of the flame; they are converted by growth, association and chemical transformation into solid soot particles. In thermal systems, the mechanisms involved are identical except that nucleation on ions may be disregarded. In both systems, nucleation of microdroplets is a fast and discontinuous phenomenon. Such an understanding in C particle formation might be efficiently used to reduce noticeably atmospheric pollution and energy loss by soot formation.     

Advances in biosecurity to 2010 and beyond: Towards integrated detection,analysis and response to exotic pest invasions

In order to limit the number and impact of exotic pest invasions, leading-edge technologies must be embraced and embedded within integrated national and international biosecurity systems. Outlined here are recent advances in the detection of exotic pests, and prospects for the early recognition of disease. Applications of new tools are described, using our understanding of the genomes of pathogens and vectors. In addition, the role of mathematical and simulation models to aid both biosecurity planning, and decision making in the face of an epidemic, are discussed, and recent attempts to unify epidemiology and evolutionary dynamics are outlined. Given the importance of emerging diseases and zoonoses, the need to align human and veterinary surveillance within fully integrated systems is underlined.     

Purification of secretory immunoglobulin A from milk of the brushtail possum (Trichosurus vulpecula)

AIM: To identify and purify secretory immunoglobulin A (sIgA), a key effecter molecule in mucosal immune responses, from milk of the brushtail possum (Trichosurus vulpecula).

METHODS: Milk samples were collected from female possums with pouch young, and clarified by centrifugation and precipitation methods. The clarified fraction was purified by gel filtration and affinity chromatography to yield sIgA. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting techniques were used to assess the purity of the final product, and to identify the heavy (H) chain, light (L) chain and secretory component (SC) of possum sIgA.

RESULTS: Immunoblotting, using antibodies raised against cloned possum sIgA SC and H-chain, and a synthetic peptide fragment of the H-chain, confirmed the identity of the purified protein. The N-terminal amino acid sequence of purified possum sIgA showed strong homology to reported sequences of H-chain variable regions of marsupial immunoglobulins.

CONCLUSIONS: Milk was shown to be a convenient source of mucosal secretion containing sIgA, and a process involving 2 precipitation and 2 chromatography steps produced purified sIgA. This IgA preparation will prove useful for the generation of sIgA-specific immunological reagents for measurement of immune responses in the development of mucosal-based vaccines for biological control of possums.     

Boron fertilization and liming for Eucalyptus urograndis cropped on sandy arenosol of Brazilian pampa

Boron (B) requirement and its interaction with liming for eucalyptus plantations in sandy soils of Brazilian Pampa are poorly understood. Aiming to diminish this gap, seedlings of Eucalyptus urograndis were grown in pots with Arenosol fertilized with B at rates 0.0, 1.0, 2.5, 5.0 and 10.0 mg B dm^?3, with and without liming. Results of shoot and root dry matter and stem diameter did not evidence the necessity of B fertilization. With the exception of the 1.0 mg B dm^?3+lime, all other B-fertilized treatments promoted visual symptoms of toxicity, which were partially mitigated by liming. Liming exacerbated the B loss by leaching, but after five months, limed soils had higher content of available B and their plants had higher B concentration in shoots and roots. For our conditions, application of ≥2.5 mg B dm^?3 can cause serious toxic injuries to plants and enlarge dramatically the B losses leaching.     

Morphological and molecular characterization of different Echinochloa spp. and Oryza sativa populations

Echinochloa P. Beauv. is an important genus because many of its species are weeds infesting most paddy fields, which can reduce the rice grain production by up to 80%. A controversy exists about the taxonomy of the genus due to the high level of morphological variations found in these species. Cyhalofop-butyl, an aryloxyphenoxy-propionate herbicide, is used to control Echinochloa spp. in paddy fields, although differences in susceptibility were found between different Echinochloa species. E. colona was highly susceptible [ED50= 34 g of active ingredient (ai) ha(-1)]; very similar results were obtained with the remaining species. By contrast, E. oryzicola (170 g of ai ha(-1)) was less sensitive, with the herbicide symptoms appearing later. Because of this differential susceptibility, morphological and molecular studies were carried out. A morphological study, using 21 characters both quantitative and qualitative of spikelets and seedlings, was capable of clearly distinguishing closely related E. crus-galli plants (two populations), E. muricata and E. crus-pavonis, and E. oryzicola, E. utilis, and E. colona species. The resolution of Echinochloa species at the molecular level, based on RAPD analyses, was fairly consistent with morphological analysis results. Among the 60 primers screened, 21 primers exhibited polymorphic bands and produced a total of 136 RAPD markers. Of all the amplified fragments, 90 were found to be polymorphic. E. oryzicola and E. colona were clearly separated, and the RAPD analyses showed that both E. crus-galli populations were 100% related and 51% related to E. utilis, whereas E. crus-pavonis and E. muricata (73% similarity) appeared as being clearly separated from this group.     

Reactive natural phosphate enriched with filter cake enhances soil P content and noni seedlings growth*

One of the major challenges in crop production is increase efficiency of non-renewable P sources, or replace them with renewable sources. The objective of this study is to evaluate the effects of phosphorus (P) fertilization using reactive natural phosphate, filter cake, peat and biofertilizer on soil P content, foliar P content and growth of noni seedlings. The treatments were: control (without P fertilization); phosphorus; filter cake; phosphorus?+?filter cake; phosphorus?+?filter cake?+?peat; and phosphorus?+?filter cake?+?peat?+?biofertilizer. All treatments were replicated four times and arranged in a completely randomized design. The treatments phosphorus?+?filter cake; phosphorus?+ filter cake?+?peat; and phosphorus?+?filter cake?+?peat?+?biofertilizer increased phosphorus content in soil and in leaf, and the growth of noni seedlings. Our results indicates that natural reactive phosphate enriched with filter cake can be used as phosphate fertilizer on noni seedlings cultivation.     

Growth hormones therapy in immune response against Trypanosoma cruzi

Growth hormone (GH) is an important hypophyseal hormone that is primarily involved in body growth and metabolism. In mammals, control of Trypanosoma cruzi parasitism during the acute phase of infection is considered to be critically dependent on direct macrophage activation by cytokines. To explore the possibility that GH might be effective in the treatment of Chagas’ disease, we investigated its effects on the course of T. cruzi infection in rats, focusing our analyses on its influences on parasitemia, NO, TNF-α and IFN-γ concentration and on histopathological alterations and parasite burden in heart tissue. T. cruzi-infected male Wistar rats were intraperitoneally treated with 5 ng/10 g body weight/day of GH. Animals treated with GH showed a significant reduction in the number of blood trypomastigotes during the acute phase of infection compared with untreated animals (P < 0.05). For all experimental days (7, 14 and 21 post infection) of the acute phase, infected and GH treated animals reached higher concentrations of TNF-α, IFN-γ and nitric oxide as compared to untreated and infected counterparts (P < 0.05) Histopathological observations of heart tissue revealed that GH administration also resulted in fewer and smaller amastigote burdens, and less inflammatory infiltrate and tissue disorganization, indicating a reduced parasitism of this tissue. These results show that GH can be considered as an immunomodulator substance for controlling parasite replication and combined with the current drug used may represent in the future a new therapeutic tool to reduce the harmful effects of Chagas’ disease.