BackgroundThe species of T. harzianum are well known for their biocontrol activity against many plant pathogens. However, there is a lack of studies concerning its use as a biological control agent against F. solani, a pathogen involved in several crop diseases. In this study, we have used subtractive library hybridization (SSH) and quantitative real-time PCR (RT-qPCR) techniques in order to explore changes in T. harzianum genes expression during growth on cell wall of F. solani (FSCW) or glucose. RT-qPCR was also used to examine the regulation of 18 genes, potentially involved in biocontrol, during confrontation between T. harzianum and F. solani.ResultsData obtained from two subtractive libraries were compared after annotation using the Blast2GO suite. A total of 417 and 78 readable EST sequence were annotated in the FSCW and glucose libraries, respectively. Functional annotation of these genes identified diverse biological processes and molecular functions required during T. harzianum growth on FSCW or glucose. We identified various genes of biotechnological value encoding to proteins which function such as transporters, hydrolytic activity, adherence, appressorium development and pathogenesis. Fifteen genes were up-regulated and sixteen were down-regulated at least at one-time point during growth of T. harzianum in FSCW. During the confrontation assay most of the genes were up-regulated, mainly after contact, when the interaction has been established.ConclusionsThis study demonstrates that T. harzianum expressed different genes when grown on FSCW compared to glucose. It provides insights into the mechanisms of gene expression involved in mycoparasitism of T. harzianum against F. solani. The identification and evaluation of these genes may contribute to the development of an efficient biological control agent.

Ricin is a highly toxic ribosome-inactivating lectin occurring in the seeds of castor bean (Ricinus communis L.). Castor bean grows throughout tropical and sub-tropical regions and is a very important crop due to its high seed content of ricinoleic acid, an unusual fatty acid, which has several industrial applications. However, due to the presence of the toxin, castor bean can cause death after the exposure of animals to low doses of ricin through skin contact, injection, inhalation or oral routes. Aiming to generate a detoxified genotype, we explored the RNAi concept in order to silence the ricin coding genes in the endosperm of castor bean seeds. Results indicated that ricin genes were effectively silenced in genetically modified (GM) plants, and ricin proteins were not detected by ELISA. Hemagglutination activity was not observed with proteins isolated from GM seeds. In addition, we demonstrated that seed proteins from GM plants were not toxic to rat intestine epithelial cells or to Swiss Webster mice. After oil extraction, bio-detoxified castor bean cake, which is very rich in valuable proteins, can be used for animal feeding. Gene silencing would make castor bean cultivation safer for farmers, industrial workers and society.Castor bean (Ricinus communis L.) is commercially cultivated due to the high quality and content (mainly ricinoleic acid) of its seed oil. Major producers are India, Mozambique, China and Brazil, responsible for 1.7 million, 68.9, 40.0 and 37.5 thousand tons, respectively (http://www.fao.org/faostat). India is the main oil exporter, and the United States, the European Union, and China import about 84% of the castor oil available on the international market 1,2 . Ricinoleic acid (12-hydroxy-cis-9-octadecenoic acid) confers higher stability and viscosity on castor bean oil when compared to other vegetable oils and makes it a highly valued material in the composition of lubricants, plastics, cosmetics, paints, varnishes, ethanol and biodiesel 2,3 . However, castor bean seeds contain ricin, which is a highly toxic storage 7 S lectin. Ricin is a dimeric glycoprotein constituted of A-and B-polypeptide chains covalently linked by a disulfide bond 4 . The A-chain is a ribosome-inactivating enzyme that specifically depurinates the first adenosine in the GAGA nucleotide sequence from the conserved loop on the 28 S rRNA subunit 5,6 . This modification impairs the formation of a critical rRNA stem-loop configuration, to which elongation factor 2 binds during the translocation step of translation. The B-chain binds specifically to cell surface glycoproteins or glycolipids and facilitates the movement of the A-chain into animal cells. One A-chain molecule of ricin is able to irreversibly inactivate one thousand ribosomes per minute, impairing protein synthesis and causing cell death 7 . Castor bean seeds also contain the ricin homologue R. communis agglutinin (RCA 120 ), which is a tetrameric protein composed of two A-chains (90% similar to the ricin A-chain) and two B-chains (84% similar to the ricin...

Solanum paniculatum L. is a plant species widespread throughout tropical America, especially in the Brazilian Cerrado region. It is used in Brazil for culinary purposes and in folk medicine to treat liver and gastric dysfunctions, as well as hangovers. Previous studies with S. paniculatum ethanolic leaf extract or ethanolic fruit extract demonstrated that they have no genotoxic activity neither in mice nor in bacterial strains, although their cytotoxicity and antigenotoxicity were demonstrated in higher doses. In order to assess the possible compounds responsible for the activities observed, we fractionated the ethanolic fruit extract of S. paniculatum, characterized by 1 H and 13 C NMR spectra, and evaluated two fractions containing steroidal alkaloids against mitomycin C (MMC) using the mouse bone marrow micronucleus test. Swiss mice were orally treated with different concentrations (25, 50, or 100 mg.kg -1 ) of each fraction simultaneously with a single intraperitonial dose of MMC (4 mg.kg -1 ). Antigenotoxicity was evaluated by using the frequency of micronucleated polychromatic erythrocytes (MNPCE), whereas anticytotoxicity was assessed by the polychromatic and normochromatic erythrocytes ratio (PCE/NCE). Our results demonstrated that steroidal alkaloids isolated from S. paniculatum strongly protected cells against MMC aneugenic and/or clastogenic activities as well as modulated MMC cytotoxic action.

Eugenia dysenterica DC. (Myrtaceae), popularly known in Brazil as cagaiteira, is a widespread plant species in the Brazilian Cerrado. In folk medicine, the leaves of this plant are used to treat diarrhea and dysentery. The fruits are used for fresh consumption and industrial purposes. Because of the use of this plant as a therapeutic resource and food, the present study evaluated the genotoxic, cytotoxic, antigenotoxic, and anticytotoxic effects of the lyophilized ethanolic leaf extract of E. dysenterica using the mouse bone marrow micronucleus test. The genotoxicity and antigenotoxicity of this extract were evaluated using the frequency of micronucleated polychromatic erythrocytes, and the cytotoxicity and anticytotoxicity were assessed by the polychromatic and normochromatic erythrocyte ratio. According to our results, the lyophilized ethanolic leaf extract of E. dysenterica exhibited genotoxic and cytotoxic effects at the higher doses and protection against cyclophosphamide-induced genotoxic and cytotoxic actions at all doses tested.

Solanum paniculatum L. is a plant species widespread throughout tropical America, especially in the Brazilian Savanna region. It is used in Brazil for culinary purposes and in folk medicine to treat liver and gastric dysfunctions, as well as hangovers. Because of the wide use of this plant as a therapeutic resource and food, the present study aimed at evaluating the mutagenic and cytotoxic effects of S. paniculatum ethanolic leaf and fruit extracts using the mouse bone marrow micronucleus test. Our results indicate that neither S. paniculatum ethanolic leaf extract nor its ethanolic fruit extract exhibited mutagenic ef fect in mice bone marrow; however, at higher doses, both extracts presented cytotoxic activity.Keywords: mutagenicity, cytotoxicity, Solanum paniculatum L., micronucleus, mice. Avaliação da mutagenicidade e citotoxicidade de extratos de Solanum paniculatum L. usando o teste do micronúcleo in vivo em camundongos ResumoSolanum paniculatum L., popularmente conhecida como jurubeba, ocorre em toda a América tropical, especialmente no Cerrado. No Brasil, é utilizada para fins culinários e na medicina popular para o tratamento de distúrbios gástricos e hepáticos, além de ressacas. Devido à grande utilização desta planta pela população como recurso terapêutico e alimentício, o presente estudo teve como objetivo avaliar as atividades mutagênica e citotóxica dos extratos etanólico das folhas e frutos de S. paniculatum utilizando o teste do micronúcleo em medula óssea de camundongos. Os resultados indicam que os extratos etanólicos tanto das folhas quanto dos frutos de S. paniculatum não apresentaram ação mutagênica em medula óssea de camundongos, porém, em doses mais elevadas, ambos os extratos exibiram atividade citotóxica.Palavras-chave: mutagenicidade, citotoxicidade, Solanum paniculatum L., micronúcleo, camundongos.