Made available in DSpace on 2016-04-28T20:17:26Z (GMT). No. of bitstreams: 1 2006- Glenda Ribeiro de Oliveira.pdf: 475801 bytes, checksum: 8ca6884856073fd041daad94f50fca0e (MD5) Previous issue date: 2006-11-24 / The intake of mycotoxin-contamined feeds may lead to nutrient losses and can have adverse effects on animal health and on productivity. The aims of this study were: 1) to determine the mycobiota present in poultry feed samples, obtained from three factories in the region of S?o Jos? do Vale do Rio Preto, RJ, Brazil; 2) to evaluate the natural occurrence of aflatoxin B1 (AFB1), fumonisin B1 (FB1) and zearalenone using the method enzyme linked immunosorbent assay (ELISA) competitive, commercial kits of Beacon Analytical Systems Inc, USA and 3) to verify the data results by the ELISA to AFB1 and FB1 comparing them with the high precision liquid chromatography methodology (HPLC) Fungal counts were similar between all culture media tested (103 CFU.g-1). Penicillium spp. (41,26%) was the most prevalent genus followed by Aspergillus spp. (33,33%) and Fusarium spp. (20,63%). Aflatoxin B1 was found in 66,27% samples examined by ELISA kits and values ranged between 2 and 21&#956;g.kg-1. Fumonisin B1 was found in 97,87% and levels ranged between 0,3 and 9,1&#956;g.g-1, cooccurring with aflatoxin B1 in 66,7% of the samples. Low concentrations of zearalenone were found (<1 &#956;g.g-1) in 77,1% poultry feed samples. Correlation between the ELISA kits (AFB1 and FB1) and the HPLC analysis was obtained. Values were r2= 0,9922 and r2=0,9823, respectively. In general, the highest mycotoxin levels were found during the hottest month of sampling. The present study shows the simultaneous occurrence of two carcinogenic mycotoxins, aflatoxin B1 and fumonisin B1 together with another Fusarium mycotoxin (zearalenone) in feed intended for poultry consumption. Many samples contained AFB1 levels near the maximum permissible and it could affect young animals. A synergistic toxic response is possible in animals under simultaneous exposure. / A ingest?o de ra??es contaminadas por micotoxinas pode acarretar perdas no seu valor nutritivo e causar efeitos adversos ? sa?de animal e ? produtividade. Os objetivos desse estudo foram: 1)estabelecer a freq??ncia e a preval?ncia da micobiota presente em amostras de ra??es de frangos de corte provenientes de tr?s f?bricas em S?o Jos? do Vale do Rio Preto-RJ, 2)verificar a ocorr?ncia natural de aflatoxina B1 (AFB1), fumonisina B1 (FB1) e zearalenona (ZEA), utilizando a t?cnica biol?gica de imunoensaios-ELISA competitivo, com kits comerciais (Beacon Analytical Systems Inc, USA) e 3)verificar os resultados obtidos pelo m?todo de ELISA, comparando-os com a t?cnica de Cromatografia L?quida de Alta Efici?ncia (CLAE) para AFB1 e FB1. A contagem dos prop?gulos f?ngicos foi similar entre todos os meios de cultura testados (103 UFC g-1). Penicillium spp (41,26%) foi o g?nero de maior preval?ncia seguido por Aspergillus spp (33,33%) e Fusarium spp. (20,63%). Aflatoxina B1 foi encontrada em 66,27% das amostras analisadas pelos kits de ELISA,com valores variando entre 2 e 21&#956;g.kg-1. Fumonisina B1 foi encontrada em 97,87% e os valores variaram entre 0,3 e 9,1&#956;g.g-1, co-ocorrendo com aflatoxinaB1 em 66,7% das amostras. Baixas concentra??es de zearalenona foram encontradas (< 1&#956;g.g-1)em 77,1% das amostras de ra??o. Foi obtida correla??o entre os kits de ELISA (AFB1 e FB1) e as an?lises em CLAE, com valores de r2= 0,9922 e 0,9823, respectivamente. Em geral, os maiores n?veis de micotoxinas foram encontrados durante os meses mais quentes do ano. O presente estudo mostra a ocorr?ncia simult?nea de duas micotoxinas carcinog?nicas, AFB1 e FB1, juntamente com outra Fusarium micotoxina (zearalenona) em ra??es destinadas ao consumo de frangos. Algumas amostras apresentaram n?veis de AFB1 pr?ximos ao m?ximo permitido, o que poderia afetar aves jovens. Uma resposta t?xica sin?rgica ? poss?vel em animais sob exposi??o simult?nea.

Made available in DSpace on 2017-07-10T19:24:57Z (GMT). No. of bitstreams: 1 Raquel_texto_completo.pdf: 4554269 bytes, checksum: 31b7a7e875a4461d29d0d14f512012b0 (MD5) Previous issue date: 2011-07-08 / Corn (Zea Mays L.) contributes significantly to the human being nourishment because of its nutritional characteristics. However, these characteristics also support fungus growing, which during their secondary metabolism produce toxic substances, named mycotoxins. Among mycotoxins, found more frequently in corn grains and derived products, aflatoxins B1, B2, G1 and G2 can be found and are also rated as cancer developers for human beings, as well as animals. Considering the diversity of sub products from this grain and that most of them is daily on the table of the Brazilian population, this research has the goal of evaluating the safety of corn derivates traded in the city of Cascavel Paraná, focusing on identifying the risk of the population's exposition to aflatoxins. Initially, a population survey was done to check which corn derivates products are the most consumed in the city of Cascavel Paraná, through the application of a questionnaire to the population, stratified into four categories: children (between 2 to 9 years old), teenagers (between 10 to 18 years old), young adults (between 19 to 59 years old) and elderly (above 60 years old). The city was divided into five geographical parts: East, West, North, South and downtown, and in each one of the regions one large supermarket was selected randomly and defined as the place to apply the questionnaires. After carrying out this survey, four samples of each one of the three most consumed corn products were collected. Collection was done every 15 days at the chosen supermarkets. Such samples were submitted to microbiological quality (fungus scoring) physical chemical (moist, ashes, acidity, proteins and lipids levels) and toxicological (identification and quantification of aflatoxins B1, B2, G1 and G2) tests. After finishing these analyses, the likely daily ingestion for AFB1 was estimated with the goal of checking if population was exposed to harms caused by these substances. From the population survey, it was observed that the most consumed corn derivates in the city were corn flour, popcorn and corn starch. Microbiological tests performed in those samples couldn t be analyzed as a pattern indicating quality in the products, considering the absence of a current legislation on this aspect. However, it was observed cultures similar to yeasts in the corn flour harvests whereas fungi similar to genus Aspergillus were noticed in popcorn cultures. Physical chemical tests identified that all samples were suitable to human consumption, considering the evaluated aspects. As for aflatoxins presence, subgroup B1 was detected only in one sample of corn starch, under concentration of 1 &#956;g/kg, or in an amount under the limit recommended to current legislation. In risk analyses, an IDPM of AFBI was estimated to all population categories and the people category identified as eminently in risk were children, with IDPM varying from 0,0963 t 0,1438 ng/kg body weight/day. The conclusion was that even the population layers that acquired products with low aflatoxins incidence and amount, the risk regarding harms of this substance must be periodically checked, considering that in this research only one sample was positive for AFB1. However, IDPM for children was considered going nearly beyond limit. / O milho (Zea mays L.) contribui de forma significativa para a alimentação do ser humano, em virtude de suas características nutricionais. Em contrapartida, estas mesmas características também favorecem o crescimento de determinados fungos, os quais, durante seu metabolismo secundário, produzem compostos tóxicos denominados micotoxinas. Dentre as micotoxinas encontradas com maior frequência em grãos de milho e produtos derivados, estão as aflatoxinas B1, B2, G1 e G2, classificadas como substâncias carcinogênicas para o ser humano e também para animais. Considerando a diversidade de subprodutos oriundos deste grão, e que a maioria está presente diariamente na mesa da população brasileira, este trabalho teve por objetivo avaliar a segurança alimentar de produtos derivados de milho comercializados no município de Cascavel Paraná, com ênfase em identificar o risco de exposição desta população às aflatoxinas. Inicialmente foi realizado um inquérito populacional para verificar quais são os produtos derivados de milho mais consumidos no município de Cascavel Paraná, por meio da aplicação de um questionário à população deste município, estratificada em quatro categorias: crianças (2 a 9 anos), adolescentes (10 a 18 anos), jovens/adultos (19 a 59 anos) e idosos (60 anos ou mais). O município foi dividido em cinco quadrantes geográficos (leste, oeste, norte, sul e centro), e em cada uma das regiões foi selecionado, de maneira aleatória, um supermercado de grande porte, definido então como o local para aplicação dos questionários. Após a finalização do inquérito populacional, foram coletadas quatro amostras de cada um dos três produtos derivados de milho mais consumidos no município. Estas amostras foram submetidas a testes de qualidade microbiológica (contagem de fungos), físico-química (umidade, cinzas, acidez, teor de proteínas e lipídios) e toxicológica (identificação e quantificação de aflatoxina B1, B2, G1 e G2). Após o término destas análises, estimou-se a Ingestão Diária Provável Média (IDPM) para AFB1, com o objetivo de verificar se a população estava exposta aos malefícios ocasionados pela ingestão deste composto. A partir do inquérito populacional, identificou-se que os produtos derivados de milho mais consumidos no município eram o fubá, a pipoca e o amido de milho. Os ensaios microbiológicos realizado nestas amostras não puderam ser analisados como parâmetro indicador de qualidade destes produtos, tendo em vista a ausência de uma legislação em vigência quanto a este aspecto, porém, salienta-se que nas culturas de fubá foram visualizadas culturas semelhantes a leveduras, enquanto que, nas culturas de pipoca, verificou-se a presença de colônias de fungos semelhantes ao gênero Aspergillus. Os ensaios físico-químicos identificaram que todas as amostras estavam adequadas para o consumo humano, quanto aos aspectos avaliados. Quanto à presença de aflatoxinas, o subgrupo B1 foi detectado somente em uma amostra de amido de milho, na concentração de 1 &#956;g/kg, ou seja, quantidade inferior ao limite preconizado pela legislação vigente. Na análise de risco, estimou-se a IDPM de AFBI para todas as categorias populacionais analisadas, e o público identificado como eminentemente em risco foram as crianças, com IDPM variando de 0,0963 a 0,1438 ng/kg peso corpóreo/dia. Concluiu-se que, mesmo em populações que adquiram produtos com baixa incidência e quantidade de aflatoxinas, o risco quanto aos malefícios deste composto deve ser periodicamente observado, tendo em vista que neste estudo apenas uma amostra foi positiva para AFB1, entretanto, a IDPM para as crianças foi considerada limítrofe.

A aflatoxina M1 (AFM1) é um metabólito tóxico resultante da biotransformação da aflatoxina B1 e pode ser secretada no leite de animais que ingerem alimentos contaminados com esta última. Considerando os efeitos adversos que podem ocorrer devido à ingestão do produto contaminado e visto que as crianças, maiores consumidoras deste alimento, são potencialmente mais sensíveis que os adultos aos efeitos desta micotoxina, a avaliação da presença de AFM1 no leite se faz necessária. Durante o período de março a novembro de 2006 foram analisadas 48 amostras de leite cru provenientes de 8 propriedades fornecedoras de leite para uma Cooperativa de Leite da Serra Gaúcha e 80 amostras de leite UHT, provenientes de 7 marcas distintas, comercializadas em Porto Alegre (RS). A metodologia empregada na análise de aflatoxina M1 envolveu partição líquido-líquido na etapa de extração, uso de coluna de sílica gel na etapa de purificação e Cromatografia em Camada Delgada para a detecção. O limite de detecção foi de 10 ng e a avaliação da eficiência do método apresentou valor de 86% no teste de recuperação. Nas condições de trabalho e pelo método utilizado nenhuma das amostras analisadas foi positiva para a presença de AFM1, sugerindo que as mesmas encontram-se dentro das conformidades legais. / Aflatoxin M1 (AFM1) is a toxic metabolite resulting of the biotransformation of aflatoxin B1, and may be sectreted in milk of animals that consume foods contaminated with aflatoxin B1. Considering the adverse effects that can occur when foods contaminated are consumed, and since children, the greatest milk consumer are potentially more susceptible than adults to the effects of this mycotoxin, the evaluation of the presence of AFM1 in milk is necessary. From March to November of 2006 48 samples of raw milk from 8 dairy farms that integrate a Milk Cooperative of mountain region of Rio Grande do Sul and 80 samples of UHT milk from 7 different brands commercialized in Porto Alegre were analized. The mehodology employed for the analysis of aflatoxin M1 involved liquid-liquid partition on the extraction step, use of silic gel column for the purification step and Thin Layer Chromatography for the detection. The evaluation of the method efficiency present a value of 86% in the recovery test and the detection level was 10ng. Following analysis conditions and the method employed none of the samples analyzed were positive for the presence of aflatoxin M1, suggesting that samples analysed attend the legal conformities.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2018-08-22T11:24:50Z No. of bitstreams: 1 2010 - Vin?cius Machado dos Santos.pdf: 995846 bytes, checksum: 696b6b0e2360cb9f5762b0890f9801b2 (MD5) / Made available in DSpace on 2018-08-22T11:24:50Z (GMT). No. of bitstreams: 1 2010 - Vin?cius Machado dos Santos.pdf: 995846 bytes, checksum: 696b6b0e2360cb9f5762b0890f9801b2 (MD5) Previous issue date: 2010-09-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / A study was carried out to evaluate the use of Saccharomyces cerevisiae cell wall (SCCW) as an anti-mycotoxin additive in broiler chicks? diets slaughtered at 22 day age on performance, carcass characteristics and organ weights. It was used a randomized complete block design with four treatments in a factorial 2 (with aflatoxin, without aflatoxin) x 2 (with adsorbent, without adsorbent). For the performance parameters evaluated, there was a significant difference only on feed intake, when the SCCW was added to the rations. There was no interaction between aflatoxin and SCCW factors in the diet on the performance variables studied. The addition of SCCW to the chicks? diets stimulated the feed intake during 1-21 days of age. However, that did not reflect a significant increase in weight gain, or a change in feed conversion. There was a significant interaction between factors aflatoxin and SCCW on the weight post-fasting, cold carcass weight and thigh+upper weight. For the absolute hot carcass weights, breast, back and wings and carcass yields and relative weights of the cuts it was not observed a significant interaction between factors. The growth performance of broilers in the period 1-21 days old was not influenced by the levels of aflatoxin and SCCW factors used in experimental diets. Nevertheless for body weight after fasting, the cold carcass weight and absolute weight of the thigh + drumstick, the SCCW acted as an anti-mycotoxin additive by minimizing the aflatoxin toxicity. / Objetivou-se com este experimento avaliar a utiliza??o da parede celular de Saccharomyces cerevisiae (PCSC) como aditivo antimicotoxina em ra??es destinadas a frangos de corte abatidos aos 22 dias de idade sobre o desempenho, caracter?sticas de carca?a e pesos de ?rg?os. Foi adotado um delineamento experimental em blocos casualizados, com 4 tratamentos dispostos em um esquema fatorial 2 (sem aflatoxina; com aflatoxina) x 2 (sem adsorvente; com adsorvente). Para os par?metros de desempenho avaliados, observou-se diferen?a significativa apenas sobre o consumo alimentar, quando a PCSC foi adicionada ?s ra??es. N?o houve intera??o entre os fatores aflatoxina e PCSC nas ra??es sobre as vari?veis de desempenho estudadas. A adi??o de PCSC ? ra??o dos frangos estimulou o consumo de ra??o no per?odo de 1 a 21 dias de idade, entretanto, isso n?o se refletiu em aumento significativo no ganho de peso dos frangos ou altera??o na convers?o alimentar. Houve intera??o significativa entre os fatores aflatoxina e PCSC sobre o peso vivo p?s-jejum, carca?a resfriada e o peso da coxa+sobrecoxa. Para os pesos absolutos de carca?a quente, peito, dorso e asas, rendimento das carca?as e pesos relativos dos cortes n?o se observou intera??o significativa entre os fatores estudados. O desempenho zoot?cnico de frangos de corte no per?odo de 1 a 21 dias de idade n?o foi influenciado pelos n?veis dos fatores aflatoxina e PCSC utilizados nas ra??es experimentais. J? para peso vivo p?s-jejum, peso da carca?a resfriada e peso absoluto da coxa+sobrecoxa, houve uma poss?vel atua??o da PCSC como aditivo antimicotoxina, ao minimizar a a??o t?xica da aflatoxina.

Made available in DSpace on 2017-05-12T14:48:19Z (GMT). No. of bitstreams: 1 Raquel_texto_completo.pdf: 4554269 bytes, checksum: 31b7a7e875a4461d29d0d14f512012b0 (MD5) Previous issue date: 2011-07-08 / Corn (Zea Mays L.) contributes significantly to the human being nourishment because of its nutritional characteristics. However, these characteristics also support fungus growing, which during their secondary metabolism produce toxic substances, named mycotoxins. Among mycotoxins, found more frequently in corn grains and derived products, aflatoxins B1, B2, G1 and G2 can be found and are also rated as cancer developers for human beings, as well as animals. Considering the diversity of sub products from this grain and that most of them is daily on the table of the Brazilian population, this research has the goal of evaluating the safety of corn derivates traded in the city of Cascavel Paraná, focusing on identifying the risk of the population's exposition to aflatoxins. Initially, a population survey was done to check which corn derivates products are the most consumed in the city of Cascavel Paraná, through the application of a questionnaire to the population, stratified into four categories: children (between 2 to 9 years old), teenagers (between 10 to 18 years old), young adults (between 19 to 59 years old) and elderly (above 60 years old). The city was divided into five geographical parts: East, West, North, South and downtown, and in each one of the regions one large supermarket was selected randomly and defined as the place to apply the questionnaires. After carrying out this survey, four samples of each one of the three most consumed corn products were collected. Collection was done every 15 days at the chosen supermarkets. Such samples were submitted to microbiological quality (fungus scoring) physical chemical (moist, ashes, acidity, proteins and lipids levels) and toxicological (identification and quantification of aflatoxins B1, B2, G1 and G2) tests. After finishing these analyses, the likely daily ingestion for AFB1 was estimated with the goal of checking if population was exposed to harms caused by these substances. From the population survey, it was observed that the most consumed corn derivates in the city were corn flour, popcorn and corn starch. Microbiological tests performed in those samples couldn t be analyzed as a pattern indicating quality in the products, considering the absence of a current legislation on this aspect. However, it was observed cultures similar to yeasts in the corn flour harvests whereas fungi similar to genus Aspergillus were noticed in popcorn cultures. Physical chemical tests identified that all samples were suitable to human consumption, considering the evaluated aspects. As for aflatoxins presence, subgroup B1 was detected only in one sample of corn starch, under concentration of 1 &#956;g/kg, or in an amount under the limit recommended to current legislation. In risk analyses, an IDPM of AFBI was estimated to all population categories and the people category identified as eminently in risk were children, with IDPM varying from 0,0963 t 0,1438 ng/kg body weight/day. The conclusion was that even the population layers that acquired products with low aflatoxins incidence and amount, the risk regarding harms of this substance must be periodically checked, considering that in this research only one sample was positive for AFB1. However, IDPM for children was considered going nearly beyond limit. / O milho (Zea mays L.) contribui de forma significativa para a alimentação do ser humano, em virtude de suas características nutricionais. Em contrapartida, estas mesmas características também favorecem o crescimento de determinados fungos, os quais, durante seu metabolismo secundário, produzem compostos tóxicos denominados micotoxinas. Dentre as micotoxinas encontradas com maior frequência em grãos de milho e produtos derivados, estão as aflatoxinas B1, B2, G1 e G2, classificadas como substâncias carcinogênicas para o ser humano e também para animais. Considerando a diversidade de subprodutos oriundos deste grão, e que a maioria está presente diariamente na mesa da população brasileira, este trabalho teve por objetivo avaliar a segurança alimentar de produtos derivados de milho comercializados no município de Cascavel Paraná, com ênfase em identificar o risco de exposição desta população às aflatoxinas. Inicialmente foi realizado um inquérito populacional para verificar quais são os produtos derivados de milho mais consumidos no município de Cascavel Paraná, por meio da aplicação de um questionário à população deste município, estratificada em quatro categorias: crianças (2 a 9 anos), adolescentes (10 a 18 anos), jovens/adultos (19 a 59 anos) e idosos (60 anos ou mais). O município foi dividido em cinco quadrantes geográficos (leste, oeste, norte, sul e centro), e em cada uma das regiões foi selecionado, de maneira aleatória, um supermercado de grande porte, definido então como o local para aplicação dos questionários. Após a finalização do inquérito populacional, foram coletadas quatro amostras de cada um dos três produtos derivados de milho mais consumidos no município. Estas amostras foram submetidas a testes de qualidade microbiológica (contagem de fungos), físico-química (umidade, cinzas, acidez, teor de proteínas e lipídios) e toxicológica (identificação e quantificação de aflatoxina B1, B2, G1 e G2). Após o término destas análises, estimou-se a Ingestão Diária Provável Média (IDPM) para AFB1, com o objetivo de verificar se a população estava exposta aos malefícios ocasionados pela ingestão deste composto. A partir do inquérito populacional, identificou-se que os produtos derivados de milho mais consumidos no município eram o fubá, a pipoca e o amido de milho. Os ensaios microbiológicos realizado nestas amostras não puderam ser analisados como parâmetro indicador de qualidade destes produtos, tendo em vista a ausência de uma legislação em vigência quanto a este aspecto, porém, salienta-se que nas culturas de fubá foram visualizadas culturas semelhantes a leveduras, enquanto que, nas culturas de pipoca, verificou-se a presença de colônias de fungos semelhantes ao gênero Aspergillus. Os ensaios físico-químicos identificaram que todas as amostras estavam adequadas para o consumo humano, quanto aos aspectos avaliados. Quanto à presença de aflatoxinas, o subgrupo B1 foi detectado somente em uma amostra de amido de milho, na concentração de 1 &#956;g/kg, ou seja, quantidade inferior ao limite preconizado pela legislação vigente. Na análise de risco, estimou-se a IDPM de AFBI para todas as categorias populacionais analisadas, e o público identificado como eminentemente em risco foram as crianças, com IDPM variando de 0,0963 a 0,1438 ng/kg peso corpóreo/dia. Concluiu-se que, mesmo em populações que adquiram produtos com baixa incidência e quantidade de aflatoxinas, o risco quanto aos malefícios deste composto deve ser periodicamente observado, tendo em vista que neste estudo apenas uma amostra foi positiva para AFB1, entretanto, a IDPM para as crianças foi considerada limítrofe.

<p style="text-align: justify;">Prisustvo plesni i mikotoksina u hrani predstavlja vi&scaron;estruku opasnost, kako sa aspekta bezbednosti hrane, tako i sa aspekta globalne trgovine. Učestalost i intenzitet pojave plesni na uzorcima zrna hlebne p&scaron;enice i spelte prikupljenih u regionu Vojvodine određeni su nakon žetve tokom trogodi&scaron;njeg perioda (2015-2017). Istraživanja su obuhvatila identifikaciju i karakterizaciju 38 izolata A. flavus primenom polifaznog pristupa koji uključuje klasične mikrobiolo&scaron;ke i molekularne metode. Ispitivanjem potencijala biosinteze AFB₁ izolata A. flavus utvrđeno je da su dva izolata poreklom sa zrna hlebne p&scaron;enice pokazala aflatoksigeni potencijal. Ve&scaron;tačka inokulacija različitih Triticum vrsta: hlebne p&scaron;enice, spelte, korasan i hibrida p&scaron;enice toksigenim izolatama izvr&scaron;ena je u fazi cvetanja u cilju poređenja otpornosti ovih vrsta na pojavu A. flavus i produkciju AFB₁. Visok nivo AFB₁ (256 &mu;g/kg) je kvantifikovan samo u zrnu spelte, dok kod drugih Triticum vrstama, zrno nije bilo kontaminirano AFB₁ (&lt;LOD). Određivanjem fizičko-hemijskih karakteristika plevičastih omotača Triticum vrsta potvrđen je njihov potencijalni uticaj na rast i razvoj A. flavus i biosintezu AFB₁. Efekti različitih temperatura (15, 23, 30 i 37&deg;C) i aktivnosti vode (0,85; 0,90; 0,95 i 0,99) na biosintezu AFB₁ ispitani su na ve&scaron;tački inokulisanim uzorcima spelte sa plevičastim omotačima kao i prethodno olju&scaron;tenim zrnima. Optimalni uslovi za biosintezu tj. uslovi pri kojima je ostvaren najveći prinos AFB₁ bili su temperatura 30 &deg;C i aw 0,99 u svim tipovima uzoraka (zrna spelte inkubirana bez plevičastih omotača - ZBPO, plevičasti omotači - PO i zrna nakon lju&scaron;tenja tj. olju&scaron;tena zrna - OZ). Rezultati su pokazali da je prisustvo plevičastih omotača bilo za&scaron;titna barijera za razvoj infekcije i akumulaciju AFB₁ u zrnu. Matematički modeli, razvijeni primenom faktora sa visokom značajno&scaron;ću kao &scaron;to su temperatura skladi&scaron;tenja i aktivnost vode, mogu biti kori&scaron;ćeni u predviđanju akumulacije AFB₁ u zrnu spelte &scaron;to predstavlja ključni korak u proceni rizika. Ispitivanjem uticaja različitih nivoa kontaminacije spelte AFB₁ u poređenju sa kontrolnim nekontaminiranim uzorkom ukazano je na smanjenje određenih parametara tehnolo&scaron;kog kvaliteta i potencijalne gubitke pecivnih svojstava speltinog bra&scaron;na pri sadržaju AFB₁ od&nbsp;&nbsp; 50 &mu;g/kg i 250 &mu;g/kg.</p> / <p>The presence of fungi and mycotoxins in food presents a multiple risk, both from the aspect of food safety and from the aspect of global trade. The frequency and incidence of mycobiota on common wheat and spelt grains samples collected in the region of Vojvodina were determined after harvest during the three-year period (2015-2017). The research covered the identification and characterization of 38 A. flavus isolates using a polyphase approach including classical microbiological and molecular methods. Testing the A. flavus isolates for AFB₁ biosynthesis, it was found that two isolates originating from wheat grains possess the aflatoxigenic potential. Artificial inoculation of different Triticum species: common wheat, spelt, khorasan and hybrid wheat with toxigenic isolates was carried out in the flowering stage in order to compare the resistance of these species to the occurrence of A. flavus and the production of AFB₁. The highest AFB₁ level (256 &mu;g/kg) was determined only in the dehulled spelt grains, in comparison to other species where AFB₁ was not detected in dehulled grains. In order to investigate the impact of wheat hulls on development of A. flavus, including the biosynthesis of toxic fungal metabolites, physico-chemical and structural properties of different Triticum spp. hulls were characterized. The effects of different temperatures (15, 23, 30 and 37 &deg; C) and water activity (0.85; 0.90; 0.95 and 0.99) on AFB₁ biosynthesis were examined on artificially inoculated hull-less as well as hulled spelt grains. The optimal conditions for AFB₁ biosynthesis (the conditions in which the highest AFB₁ yield was achieved) were temperature 30 &deg;C and 0.99 aw in the all tested spelt samples (hull-less grain, dehulled grains and hulls). Accumulation of AFB₁ was significantly higher in hull-less than in dehulled grains that implicate the protective effect of spelt hulls. Mathematical models, developed using high-significance factors such as storage temperature and water activity, can be used to predict the accumulation of AFB₁ in spelt grains, which is a key step in risk assessment. By examining the influence of different levels contamination levels of spelt grain with AFB₁ and comparing to the control (uncontaminated) sample, the reduction in certain technological quality parameters and the potential loss of dough properties of spelt flour with AFB₁ content of 50 &mu;g/kg and 250 &mu;g/kg was pointed out.</p>

The U.S. is the largest maize producer in the world with a production of 300 million tons in 2012. Approximately 86% of the maize production is focused on the Midwestern states. The rest of the production is focused in the Southern states, where Texas is the largest maize producer. Grain yield in Texas ranges from 18 tons/ha in the irrigated production zones to 3 tons/ha in the dryland production zones. As a result, grain yield has increased slowly because of the poor production in the non-irrigated acres. Methods to improve the grain yield in Texas is to breed for maize varieties adapted to Texas growing conditions, including mapping genes that can be incorporated into germplasm through marker assisted selection. This dissertation includes two separate projects that exploit historical data and maize diversity to increase grain yield in Texas. For the first project, a large dataset collected by Texas AgriLife program was analyzed to elucidate past trends and future hints on how to improve maize yield within Texas. This study confirmed previous reports that the rate of increase for grain yield in Texas is less than the rate observed in the Midwestern US. For the second project, a candidate gene and whole genome association mapping analysis was performed for drought and aflatoxin resistance in maize. In order to do so, maize inbred lines from a diversity panel were testcrossed to isogenic versions of Tx714. The hybrids were evaluated under irrigated and non-irrigated conditions. The irrigated trials were inoculated with Aspergillus flavus and the aflatoxin level was quantified. This study found that the gene ZmLOX4 was associated with days to silk, and the gene ZmLOX5 gene was associated with plant and ear height. In addition, this study identified 13 QTL variants for grain yield, plant height, days to anthesis and days to silk. Furthermore, this study shows that diverse maize inbred lines can make hybrids that out yield commercial hybrids under heat and drought stress. Therefore, there are useful genes present in these diverse lines that can be exploited in maize breeding programs

Studies described in this thesis were aimed at characterizing the mechanism(s) of aflatoxin B1 (AFB1) pulmonary carcinogenesis by addressing the formation, prevention, and repair of AFB1-induced oxidative DNA damage. The ability of AFB1 to cause oxidative DNA damage in different lung cell types of the A/J mouse was examined. The formation of 8-hydroxy-2’-deoxyguanosine (8-OHdG) in freshly isolated mouse lung alveolar macrophages, alveolar type II cells, and nonciliated bronchial epithelial (Clara) cells, was assessed by high performance liquid chromatography with electrochemical detection. An increase in 8-OHdG formation occurred in macrophage and Clara cell preparations isolated from A/J mice two hours following in vivo treatment with a single tumourigenic dose of AFB1. Prior treatment with polyethylene glycol-conjugated catalase (PEG-CAT) prevented the AFB1-induced increase in 8-OHdG levels in all mouse lung cell preparations. These results support the possibility that oxidative DNA damage in mouse lung cells contributes to AFB1 carcinogenicity. Mouse lung tumourigenesis was assessed following treatment of A/J mice with PEG-CAT and/or AFB1. Unexpectedly, the mean number of tumours per mouse and tumour size in the PEG-CAT + AFB1 group were greater than those of the group treated with AFB1 alone. There was no difference in K-ras exon 1 mutation spectrum or in the histological diagnosis of tumours between treatment groups. In vitro incubation with mouse liver catalase (CAT) resulted in conversion of [3H]AFB1 into a DNA-binding species, a possible explanation for the results observed in vivo. These results demonstrate that PEG-CAT is not protective against AFB1 carcinogenicity in mouse lung despite preventing DNA oxidation. The effect of in vivo treatment of mice with AFB1 on pulmonary and hepatic base excision repair (BER) activities and levels of 8-oxoguanine DNA glycosylase (OGG1) was investigated. AFB1 treatment increased 8-OHdG levels and BER activity in mouse lung, but did not significantly affect either in liver. Levels of OGG1 immunoreactive protein were increased in both mouse lung and liver. These results indicate that oxidative DNA damage may be an important mechanism in the carcinogenicity of AFB1. However, BER activity is increased by AFB1 treatment, possibly representing a compensatory response to the production of oxidative DNA damage. / Thesis (Ph.D, Pharmacology & Toxicology) -- Queen's University, 2008-12-12 10:00:44.81

Le aflatossine sono tra i composti naturali conosciuti più cancerogeni. Queste molecole, tossiche sia per gli animali sia per l’uomo, sono prodotte su importanti colture, quali mais, arachidi e cotone da differenti specie fungine di Aspergillus in particolare quelli afferenti alla sezione Flavi. In Italia il principale fungo responsabile della contaminazione da aflatossine su mais è A. flavus e l’area più esposta alla contaminazione è il nord della penisola dove si localizza circa il 90% della coltivazione del mais. Generalmente, le condizioni climatiche in questa area non sono favorevoli alla contaminazione da aflatossine; comunque stress idrico e alte temperature possono verificarsi durante il ciclo di crescita del mais favorendo la produzione di AFB1 da parte del fungo e determinando un accumulo superiore ai limiti di legge, come accadde nel 2003. Infatti, a partire dal 2003 più attenzione è stata dedicata alla caratterizzazione della popolazione italiana di A. flavus associate alla coltivazione del mais e allo sviluppo di una valida tecnica, come il controllo biologico degli isolati tossigeni mediante l’utilizzo di isolati non tossigeni, per ridurre la contaminazione da aflatossine. / Aflatoxins are the most carcinogenic natural compound known in nature. These molecules, toxic for animal and humans, are produced on important economic commodities worldwide by the secondary metabolism of several fungal species of Aspergilli of the section Flavi. In Italy the principal responsible of aflatoxins contamination on maize is A. flavus and the more exposed area to contamination is the northern of the peninsula where almost 90% of the cultivation is located. Generally, climatic conditions in this area are not favourable for aflatoxins contamination; however, reduced rainfall and increased temperature during maize developing season can occur along with associated levels of AFB1 exceeding the legal limits, as happened in 2003. Since this year, more attention has been dedicated to characterize Italian A. flavus populations associated with maize cultivation and to develop a useful tool to reduce aflatoxins contamination. To accomplish this goal, vegetative compatibility analysis, identification of atoxigenic isolates, evaluation of the ability of atoxigenic isolates to reduce in vitro aflatoxins produced by toxigenic isolates in vitro, selection of atoxigenic isolates potentially useful as biocontrol agents, individuate deletions in the aflatoxin biosynthesis gene cluster of selected atoxigenic isolates and biocontrol field trial with the selected potential biocontrol agents were achieved.

H παρούσα διδακτορική διατριβή στοχεύει στη διερεύνηση της σχέσης του οξειδωτικού στρες με τη σκληρωτιακή διαφοροποίηση και την παραγωγή αφλατοξίνης του μύκητα Aspergillus flavus. Ο μύκητας αυτός έχει σπουδαία αγροτική σημασία διότι μπορεί να επιμολύνει αποθηκευμένους καρπούς. Επίσης μπορεί να αποτελεί παθογόνο μικροοργανισμό για τον άνθρωπο που σχετίζεται με ασπεργιλλώσεις των πνευμόνων και άλλες λοιμώξεις. Πολλά στελέχη παράγουν μεγάλες ποσότητες αφλατοξίνης, μιας καρκινογόνου και εξαιρετικά τοξικής ένωσης. Συγκεκριμένα, διερευνήθηκε ο ρόλος κεντρικών παραμέτρων του οξειδωτικού στρες όπως η λιπιδική και πρωτεϊνική υπεροξείδωση, η θειολική οξειδοαναγωγική κατάσταση αλλά και συγκεκριμένων αντιοξειδωτικών ενζύμων, καθώς και η επίδραση συγκεκριμένων αντιοξειδωτών στη σκληρωτιακή διαφοροποίηση ενός στελέχους αγρίου τύπου σε σύγκριση με ένα μεταλλαγμένο μη σκληρωτιογόνο και μη αφλατοξινογόνο στέλεχος (ΔveA). Για την ολοκλήρωση αυτής της διατριβής χρειάστηκε η ανάπτυξη νέων μεθοδολογιών για την ποσοτικοποίηση στους μύκητες της ολικής πρωτεΐνης, και εξειδικευμένων θειολικών και λιπιδικών παραμέτρων του οξειδωτικού στρες. Τα αποτελέσματα της διατριβής δείχνουν μια σαφή συσχέτιση του οξειδωτικού στρες με τη διαφοροποίηση των σκληρωτιογόνων μυκήτων, αφού το αγρίου τύπου στέλεχος εμφανίζεται περισσότερο στρεσαρισμένο οξειδωτικά σε σύγκριση με το αδιαφοροποίητο μεταλλαγμένο στέλεχος. Η χορήγηση αντιοξειδωτών ανέστειλε πλήρως (με εξαίρεση το ασκορβικό οξύ) τη σκληρωτιογένεση του αγρίου τύπου στελέχους επιδρώντας διαφορετικά στις παραμέτρους του οξειδωτικού στρες, ενώ μείωσε έως ανέστειλε πλήρως τη βιοσύνθεση αφλατοξίνης, αποκαλύπτοντας τη συμμετοχή του οξειδωτικού στρες σε αυτές τις διαδικασίες. Τα αποτελέσματα της διατριβής εκτός από επιστημονικό ενδιαφέρον έχουν και πρακτική σημασία εξαιτίας της παθογένειας του συγκεκριμένου μύκητα τόσο στον άνθρωπο όσο και στα φυτά. / The present thesis aims to elucidate the relationship between oxidative stress and sclerotial differentiation and aflatoxin production of the fungus Aspergillus flavus. This fungus has great agricultural importance because it can infect stored grains. It can also be a human pathogen, associated with aspergillosis of the lungs and other infections. Many strains produce significant quantities of aflatoxin, a carcinogenic and acutely toxic compound. In particular, the role of central parameters of oxidative stress such as lipid and protein peroxidation, thiol redox state and antioxidant enzymes, and the influence of certain related exogenous antioxidants were studied on the biosynthesis of aflatoxin, on the biogenesis of sclerotia in a wild type in comparative relationship with a non-sclerotiogenic and non-aflatoxigenic mutant strain (ΔveA). The experimental needs of this thesis necessitates the development of new methodologies for the precise quantification of certain thiol and lipid markers of oxidative stress and protein concentration. The results show a clear relationship between oxidative stress and sclerotial differentiation since the wild type strain is more oxidatively stressed than the mutant non-differentiating strain. Administration of certain antioxidants completely inhibited sclerotiogenesis in the wild type strain (with the exception of ascorbic acid), and decreased or even halted the biosynthesis of aflatoxin, thus revealing an implication of oxidative stress on these processes. The results besides having scientific interest, have also practical importance since this fungi is both human and plant pathogen.