Contaminação de aflatoxinas em castanha-do-brasil com casca em sistemas extrativista e de plantio.

Diante de problemas de contaminação por aflatoxinas enfrentados na cadeia produtiva da castanha-do-brasil, o objetivo deste trabalho foi estudar o teor de aflatoxinas em castanhas com casca em diferentes etapas dos sistemas de produção: extrativista e de plantio. A produção extrativista consiste na coleta de ouriços recém caídos das árvores e permanecidos no solo por vários dias, empilhamento na floresta, abertura e seleção de castanhas com casca, seguida de armazenamento/secagem sob ventilação durante vários meses. Contudo, no sistema de plantio somente os ouriços com menos de 5 dias no solo são coletados, em seguida são desinfectados com hipoclorito de sódio a 1% e armazenados sob ventilação até abertura e seleção das castanhas com casca. Sessenta amostras de castanha-do-brasil com casca foram coletadas diretamente ou após abertura dos ouriços na região amazônica do Brasil, provenientes da produção extrativista no Acre e do sistema de plantio no Amazonas. As aflatoxinas (B1, B2, G1, G2) foram determinadas por Cromatografia Líquida de Alto Desempenho com detector de fluorescência bem como a atividade de água (aw) nas castanhas descascadas. Nas etapas do sistema extrativista na floresta, dos 33 ouriços coletados, castanhas provenientes de um ouriço com menos de 5 dias de contato com o solo e um ouriço empilhado durante 15 dias apresentaram contaminação por AFB1 inferior a 0,1 µg/kg de matéria fresca (MF). Entretanto o nível de AFB1 variou de 0,6 a 4,4 µg/kg de MF em 3 ouriços com mais de 30 dias em contato com o solo, mais susceptíveis a serem danificados e degradados por condições climáticas e predadores da floresta amazônica. No sistema de plantio, dos 5 ouriços coletados, somente uma amostra proveniente de um ouriço com menos de 5 dias de contato com o solo apresentou contaminação por AFB1, inferior a 0,1 µg/kg de MF. Em armazém ventilado do sistema de plantio, AFB1 foi detectada com teor inferior a 0,1 µg/kg de MF em uma amostra dos 10 ouriços coletados. Todavia no sistema extrativista, os teores de aflatoxinas das castanhas com casca aumentaram e foram superiores ao regulamento europeu (10 µg/kg de MF, UE n°165/2010) ao longo do armazenamento (até 90 dias). A secagem sob ventilação durante o armazenamento não é suficientemente eficaz para atingir rapidamente uma aw inferior a 0,7, evitando o desenvolvimento de fungos aflatoxinogênicos e a produção de aflatoxinas. Resultados sugerem o ouriço como uma barreira de proteção contra estes fungos além de confirmar os estudos anteriores do projeto Safenut que indicam a etapa de secagem sob ventilação e armazenamento das castanhas com casca durante meses no sistema extrativista como etapa crítica na contaminação por aflatoxinas. Portanto, no sistema de plantio, a coleta e o armazenamento após desinfecção com hipoclorito de sódio somente dos ouriços recém caídos das árvores, mesmo por um período de dois meses, permitem evitar a contaminação das castanhas por aflatoxinas

Adubação de soqueira de cana-de-açúcar com soluções de carbonato/bicarbonato de amônio em mistura com sais de potássio e de fósforo

Comparam-se as eficiências de soluções de aquamônia e de carbonato/bicarbonato de amônio contendo sais de K e de P quanto à produção de material seco da parte aérea e ao aproveitamento do N aplicado como fertilizante por cana-de-açúcar. Soqueiras de cana-de-açúcar da variedade "RB72454" foram transplantadas para vasos de 100 dm³ de terra e cultivadas por noventa dias. O delineamento experimental utilizado foi em esquema fatorial 2 x 3 inteiramente casualizado, com 4 repetições. Os tratamentos consistiram no fornecimento de fontes de N em combinações ou não com KCl e NH4H2PO4. Os nutrientes P e K não incluídos em cada tratamento foram aplicados em outro ponto, à mesma distância e profundidade das soqueiras que as soluções de tratamento, para assegurar a igualdade das quantidades de N, P e K aplicadas a todas as parcelas. Avaliaram-se a produção de material seco da parte aérea, a extração total de N e a recuperação do N do fertilizante. Considerou-se, para este último parâmetro, a extração do N do solo pelas soqueiras de unidades que receberam somente sais de K e de P. As soluções com carbonato/bicarbonato de amônio resultaram em maiores produções de material seco da parte aérea que as de aquamônia, porém, não diferiram quanto à extração total de N e ao N recuperado do fertilizante. A adição de KCl e NH4H2PO4 às soluções de N não interferiram na extração e na eficiência de recuperação do N aplicado, para as relações N:K e N:P:K avaliadas

Piriform spider silk sequences reveal unique repetitive elements.

Orb-weaving spider silk fibers are assembled from very large, highly repetitive proteins. The repeated segments contain, in turn, short, simple, and repetitive amino acid motifs that account for the physical and mechanical properties of the assembled fiber. Of the six orb-weaver silk fibroins, the piriform silk that makes the attachment discs, which lashes the joints of the web and attaches dragline silk to surfaces, has not been previously characterized. Piriform silk protein cDNAs were isolated from phage libraries of three species: A. trifasciata, N. claVipes, and N. cruentata. The deduced amino acid sequences from these genes revealed two new repetitive motifs: an alternating proline motif, where every other amino acid is proline, and a glutamine-rich motif of 6-8 amino acids. Similar to other spider silk proteins, the repeated segments are large (>200 amino acids) and highly homogenized within a species. There is also substantial sequence similarity across the genes from the three species, with particular conservation of the repetitive motifs. Northern blot analysis revealed that the mRNA is larger than 11 kb and is expressed exclusively in the piriform glands of the spider. Phylogenetic analysis of the C-terminal regions of the new proteins with published spidroins robustly shows that the piriform sequences form an ortholog group

A absorção de ferro pela cana de açúcar, Co 419, em função da idade

This paper describes the results obtained from the determination of iron in sugar cane according to the age of the plant, in the soil and climate conditions of the state of S. Paulo, Brazil. The iron was determined by 1-10- phenanthroline method, in samples cut monthly from 7th to 15th month from an experiment consisted de 3 plots fertilized with amonium sulfate, superphosphate and potassium cloride. The concentration of iron in the stalks and in the leaves varies according to the age of the plant. A ton of fresh stalks 15 months old contains 78,71 g of iron

Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21–22 January 2005. This geomagnetic storm has been considered "anomalous" (minimum Dst reached −105 nT at 07:00 UT on 22 January) because the main storm phase occurred during the northward excursion of the B_z component of interplanetary magnetic fields (IMFs). The monthly mean <i>F</i>_10.7 solar flux for the month of January 2005 was 99.0 sfu. The F-region parameters observed by ionosondes at Ramey (RAM; 18.5° N, 67.1° W), Puerto Rico, Jicamarca (JIC; 12.0° S, 76.8° W), Peru, Manaus (MAN; 2.9° S, 60.0° W), and São José dos Campos (SJC; 23.2° S, 45.9° W), Brazil, during 21–22 January (geomagnetically disturbed) and 25 January (geomagnetically quiet) have been analyzed. Both JIC and MAN, the equatorial stations, show unusually rapid uplifting of the F-region peak heights (<i>hp</i>F2/<i>hm</i>F2) and a decrease in the <i>Nm</i>F2 coincident with the time of storm sudden commencement (SSC). The observed variations in the F-region ionospheric parameters are compared with the TIMEGCM model run for 21–22 January and the model results show both similarities and differences from the observed results. Average GPS-TEC (21, 22 and 25 January) and phase fluctuations (21, 22, 25, 26 January) observed at Belem (BELE; 1.5° S, 48.5° W), Brasilia (BRAZ; 15.9° S, 47.9° W), Presidente Prudente (UEPP; 22.3° S, 51.4° W), and Porto Alegre (POAL; 30.1° S, 51.1° W), Brazil, are also presented. These GPS stations belong to the RBMC/IBGE network of Brazil. A few hours after the onset of the storm, large enhancements in the VTEC and <i>Nm</i>F2 between about 20:00 and 24:00 UT on 21 January were observed at all the stations. However, the increase in VTEC was greatest at the near equatorial station (BELE) and enhancements in VTEC decreased with latitude. It should be pointed out that no phase fluctuations or spread-F were observed in the Latin American sector during the post-sunset pre-reversal time in the geomagnetic disturbance (21 January). The disturbance dynamo electric field possibly resulted in downward drift of the F-region plasma and inhibited the formation of spread-F

Characterization of Aspergillus species on Brazil nut from the Brazilian Amazonian region and development of a PCR assay for identification at the genus level.

Brazil nut is a protein-rich extractivist tree crop in the Amazon region. Fungal contamination of shells and kernel material frequently includes the presence of aflatoxigenic Aspergillus species from the section Flavi. Aflatoxins are polyketide secondary metabolites, which are hepatotoxic carcinogens in mammals. The objectives of this study were to identify Aspergillus species occurring on Brazil nut grown in different states in the Brazilian Amazon region and develop a specific PCR method for collective identification of member species of the genus Aspergillus. Results:Polyphasic identification of 137 Aspergillus strains isolated from Brazil nut shell material from cooperatives across the Brazilian Amazon states of Acre, Amapá and Amazonas revealed five species, with Aspergillus section Flavi species A. nomius and A. flavus the most abundant. PCR primers ASP_GEN_MTSSU_F1 and ASP_GEN_MTSSU_R1 were designed for the genus Aspergillus, targeting a portion of the mitochondrial small subunit ribosomal RNA gene. Primer specificity was validated through both electronic PCR against target gene sequences at Genbank and in PCR reactions against DNA from Aspergillus species and other fungal genera common on Brazil nut. Collective differentiation of the observed section Flavi species A. flavus, A. nomius and A. tamarii from other Aspergillus species was possible on the basis of RFLP polymorphism. Conclusions:Given the abundance of Aspergillus section Flavi species A. nomius and A. flavus observed on Brazil nut, and associated risk of mycotoxin accumulation, simple identification methods for such mycotoxigenic species are of importance for Hazard Analysis Critical Control Point system implementation. The assay for the genus Aspergillus represents progress towards specific PCR identification and detection of mycotoxigenic species

Hemispheric asymmetries in the ionospheric response observed in the American sector during an intense geomagnetic storm

The main purpose of this investigation is to study the ionospheric F region response induced by the intense geomagnetic storm that occurred on 7-8 September 2002. The geomagnetic index Dst reached a minimum of -181 nT at 0100 UT on 8 September. In this study, we used observations from a chain of 12 GPS stations and another chain of 6 digital ionosonde stations. It should be mentioned that, soon after the sudden commencement (SC) at 1637 UT on 7 September, the TEC variations at midlatitude stations in both hemispheres showed an F region positive storm phase. However, during the recovery phase, a strong hemispheric asymmetry was observed in the ionospheric response. While a TID type soliton was observed to propagate in the Southern American sector, no TID activity was seen in the Northern American sector. Also, in the Southern Hemisphere, the TEC variations were less affected by the geomagnetic storm. The Northern Hemisphere observations showed a strong and long-lasting negative F region storm phase starting at about 1000 UT on 8 September (lasting for about 24 h). A perusal of TEC phase fluctuations and equatorial spread-F (ESF) ionospheric sounding data indicates that, on the disturbed night of 7-8 September, some stations showed the occurrence of ESF starting at about 0000 UT (2000 LT) on 8 September, whereas other stations showed that the ESF occurrence started much later, at about 0800 UT (0500 LT). This hemispheric asymmetric response of the ionospheric F region possibly indicates the presence of different mechanisms for the generation of ESF along the various latitudinal regions during the disturbed period.Facultad de Ciencias Astronómicas y Geofísica

Hemispheric asymmetries in the ionospheric response observed in the American sector during an intense geomagnetic storm

The main purpose of this investigation is to study the ionospheric F region response induced by the intense geomagnetic storm that occurred on 7-8 September 2002. The geomagnetic index Dst reached a minimum of -181 nT at 0100 UT on 8 September. In this study, we used observations from a chain of 12 GPS stations and another chain of 6 digital ionosonde stations. It should be mentioned that, soon after the sudden commencement (SC) at 1637 UT on 7 September, the TEC variations at midlatitude stations in both hemispheres showed an F region positive storm phase. However, during the recovery phase, a strong hemispheric asymmetry was observed in the ionospheric response. While a TID type soliton was observed to propagate in the Southern American sector, no TID activity was seen in the Northern American sector. Also, in the Southern Hemisphere, the TEC variations were less affected by the geomagnetic storm. The Northern Hemisphere observations showed a strong and long-lasting negative F region storm phase starting at about 1000 UT on 8 September (lasting for about 24 h). A perusal of TEC phase fluctuations and equatorial spread-F (ESF) ionospheric sounding data indicates that, on the disturbed night of 7-8 September, some stations showed the occurrence of ESF starting at about 0000 UT (2000 LT) on 8 September, whereas other stations showed that the ESF occurrence started much later, at about 0800 UT (0500 LT). This hemispheric asymmetric response of the ionospheric F region possibly indicates the presence of different mechanisms for the generation of ESF along the various latitudinal regions during the disturbed period.Facultad de Ciencias Astronómicas y Geofísica