Os DNA sintéticos anti-sentido

One old dream of the chemist in the field of the drug research is to create molecules capable of reaching their target with the precision of a missile. To accomplish it these molecules must have the propriety of distinguishing qualitative differences between healthy and diseased cells. A therapy based on this principle, able of eradicating specifically defective cells, or cells affected by a pathogen has an enormous advantage with the regard to the classical approach in which the cytotoxic drugs merely exploit quantitative biochemical and kinetic differences between abnormal and normal cells. We present in this article a review on the chemical synthesis of analogues of desoxyribonucleotides and on results obtained on the specific and irreversible inhibition of undesired genetic expression using the antisense principle

Os DNA sintéticos anti-sentido

ANTISENSE SYNTHTETIC DNA. One old dream of the chemist in the field of the drug research is to create molecules capable of reaching their target with the precision of a missile. To accomplish it these molecules must have the propriety of distinguishing qualitative differences between healthy and diseased cells. A therapy based on this principle, able of eradicating specifically defective cells, or cells affected by a pathogen has an enormous advantage with the regard to the classical approach in which the cytotoxic drugs merely exploit quantitative biochemical and kinetic differences between abnormal and normal cells. We present in this article a review on the chemical synthesis of analogues of desoxyribonucleotides and on results obtained on the specific and irreversible inhibition of undesired genetic expression using the antisense principle

Induction of defence responses by cinnamomins against Phytophthora cinnamomi in Quercus suber and Quercus ilex subs. rotundifolia

The strong association between Phytophthora cinnamomi and the mortality and decline of Quercus suber and Q. ilex subsp. rotundifolia has been known for two decades. The ability of elicitins secreted by this pathogen to trigger defence responses in these Quercus against itself was evaluated in this work. Biomass quantification by quantitative real-time PCR revealed a significant decrease in pathogen colonization of Q. suber roots after 24 h pre-treatment with α- and β-cinnamomin. In Q. suber and Q. ilex roots pre-treated with α-cinnamomin, hyphae were unable to reach and colonize the vascular cylinder and showed cytoplasmic disorganization in all the roots observed as contrasted with non-pre-treated roots. The pathogen was restricted to the intercellular spaces of the cortical parenchyma and the concomitant accumulation of electron dense materials was observed in contact with the hyphae. Furthermore, ROS (reactive oxygen species) production and the enzymatic activities of superoxide dismutase, catalase and peroxidase were compared in infected and non-infected Quercus roots in time course trials. There was a significant increase in the production of hydrogen peroxide (H2O2) and superoxide anion (O2 •-) and an enhanced activity of the enzymes in infected roots was observed at each time point. When comparing with elicitin non-treated roots, the α-cinnamomin-treated roots in interaction with P. cinnamomi showed a decrease in ROS accumulation and an increase of the enzyme activities. The overall results were consistent with an induction by the cinnamomins which initiated defence responses against the pathogen invasion of roots. Finally, elicitins were immunolocalized in the contact zone of P. cinnamomi hyphae with epidermal host cells, plasmalemma outer cytoplasm and around the intracellular hyphae in the vacuoles of invaded epidermal cells

Evaluation of fruit and seed diversity and characterization of carob (Ceratonia siliqua L.) cultivars in Algarve region

The genetic diversity of 15 carob ( Ceratonia siliqua L.) cultivars located in an experimental field from Algarve (Portugal) was evaluated over 7 years using 12 fruit and seed phenotypic characters, in order to characterize carob cultivars. The values of morphological traits obtained by cultiv ar were compared with those from other countries of the Mediterranean basin. Statistically significant differences were found between cultivars for al l characters which were examined, what indicates a high genetic diversity. The relationship among these characters was analyzed by principal component analysis (PCA) resulting in the separation of these cultivars classed in four groups (clusters I–IV) and in four ungrouped cultivars. A three dimension of the model was found to be significant and explained 74.5% of the total variation, in which the first component accounting for 34.6% of the total variation is dominated by fruit characters, while the second component is dominated by seed characters. Cultivars plotted on the left-lower quadrant on the space determined by principal components 1 and 2 are characterized by fruits with high seed yield more appropriated for industrial rentability. The correlation analyses established by cultivar provided a specific understanding about the way how fruit and seed characteristics correlate within each cultivar. This approach can be useful for the development of a breeding programme, aiming to increase the seed yield, seed thickness, individual and total seed weight by fruit, characteristics that are determinant to improve the industrial exploitation of carob

Evolução da produção de leite em pequenos ruminantes: polimorfismos do gene da hormona de crescimento

Os efetivos autóctones de pequenos ruminantes têm vindo a diminuir,em parte devido ao seu baixo potencial produtivo. A necessidade de encontrar formas mais expeditas de aumentar o potencial produtivo das nossas raças, e assim promover a sua manutenção bem como a sustentabilidade dos sistemas extensivos onde são explorados, levou à procura de marcadores moleculares, nomeadamente no gene da hormona de crescimento (GH), associados com a produção e qualidade do leite em pequenos ruminantes. Nas raças ovinas Churra da Terra Quente, Merino da Beira Baixa, Saloia e Serra da Estrela e caprinas Algarvia e Serrana verificou -se que o gene da GH é muito polimórfico, tendo sido encontrados polimorfismos específicos em algumas das raças. Os resultados sugerem que os polimorfismos do gene da GH, entre outros (e.g., nas caseínas), poderão vir a ser utilizados na seleção assistida por marcadores genéticos, de modo a melhorar da produção de leite sem afetar a sua qualidade. Contudo, a resposta à seleção será sempre condicionada pela prática de um correto maneio alimentar dos animais

Analysis of genetic diversity in Portuguese Ceratonia siliqua L. cultivars using RAPD and AFLP markers

Although carob (Ceratonia siliqua L.) is of great economic importance little is still known about the pattern of genetic variation within this species. Morphological characteristics based on 31 fruit and seeds of continuous characters determinant for agro-industrial uses, were compared with RAPD and AFLP markers for assessing genetic distances in 68 accessions of carob trees, from different cultivars, varieties and eco-geographic regions of Algarve. Eighteen selected RAPD primers applied to the 68 accessions produced a total of 235 fragments ranging from 200 to 2000 bp, of which 93 (40%) were polymorphic. Four AFLP selective primer combinations generated a total of 346 amplification fragments of which 110 were polymorphic. The average level of polymorphism based on four primer combinations was 31.8%. The phenetic trees based on RAPD and AFLP analyses gave high co-phenetic correlation values, and were found to be consistent in general with the analysis of morphological data, carried out on the same accessions. A number of RAPD and AFLP markers were found to be diagnostic for ‘Canela’ cultivar and 13 wild ungrafted trees

Growth hormone AluI polymorphism analysis in eight Portuguese bovine breeds

A total of 195 bulls of eight Portuguese beef cattle breeds (Alentejana, Arouquesa, Barros , Maronesa, Marinhoa, Mertolenga, Mirandesa and Preta) were genotyped for the GH AluI polymorphism by the polymerase chain reaction and restriction length polymorphism (PCRRFLP). The genotype and gene frequencies for each breed were determined and shown to be quite variable among the breeds. The overall gene frequencies for L and V were 0.759 and 0.241, respectively. The relation between the bGH-AluI polymorphism and growth performances was ascertained in 168 of the animals analysed. According to our results there is a significant association between the genotypes LL and LV of the bGH and the average live body weight of the animals of the breeds Alentejana, Marinhoa and Preta

Involvement of a cinnamyl alcohol dehydrogenase of Quercus suber in the defence response to infection by Phytophthora cinnamomi

A gene encoding a potential NADPH-dependent cinnamyl alcohol dehydrogenase (QsCAD1) (GenBank accession no: AY362455) was identified in Quercus suber (cork oak). Its complete cDNA sequence was obtained by RACE-PCR, starting from total RNA extracted from roots of seedlings of Q. suber, infected with Phytophthora cinnamomi, the causal agent of the decline and sudden death of Q. suber and Quercus ilex subsp. rotundifolia in the Iberian Peninsula. Sequence information to perform the RACE-PCR was acquired from a polymorphic fragment (C9), specifically identified by cDNA-AFLP, in leaves of epicormic shoots of a cork oak tree that suffered sudden death. RT-PCR and hybridization analysis showed that the QsCAD1 gene is up-regulated in root seedlings of Q. suber infected with P. cinnamomi. QsCAD1 has a high structural homology with VR-ERE (Vigna radiata), an enzyme that detoxifies eutypine (produced by Eutypa lata, the causal agent of eutypa dieback of grapevines), to eutypinol, and with QrCAD1 (Q. ilex subsp. rotundifolia), EgCAD1 (Eucalyptus gunnii), MdCAD1 (Malus x domestica). Taken together, these results suggest that these enzymes, and namely QsCAD1 belong to a new group of CAD potentially involved in deactivation of toxins produced by phytopathogens

Quercus suber infected by Phytophthora cinnamomi: effects at cellular level of cinnamomin on roots, stem and leaves

Phytophthora cinnamomi has been reported to be regularly associated with cork and holm oak decline. This oomycete secretes elicitins, a group of unique highly conserved pr oteins that can enhance plant defence reactions

Loss of Aggressiveness of Phytophthora cinnamomi (Beta-Cinnamomin Silenced Strain) in the Infection of Castanea sativa

Several forest species are severely affected by Phytophthora cinnamomi. The contribution of this oomycete to forest decline and dieback has been broadly reported. In particular, it is consensual that it is the causal agent of ink disease in Castanea sativa. It has been associated with the severe decline of Quercus species, namely the Q. suber and Q. ilex dieback in Portugal and Spain, and has been responsible for the infection of numerous native species and crops. This pathogen persists in the soil or on plant material in the form of chlamydospores allowing the infection of living root tissues when environmental conditions are favorable. © Microscopy Society of America 2012