Browsing by Author "Cravador, A."
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- 1,1-Bis(Phenylseleno)-and 1,1-Bis(Methylseleno)- alkyllithiums as building-blocks in organic synthesisPublication . Vanende, D.; Cravador, A.; Krief, A.1,1 - Bis(phenylseleno)alkyllithiums are conveniently prepared from the corresponding selenoacetals and lithium tetramethylpiperidide in HMPT/THF.
- Acidite relative des groupes methyle de la 2,4,6- collidine dans le systeme phenyllithium solvants etheresPublication . Cravador, A.La position de la métallation de la 2,4,6- collidine est fonction des conditions expérimentales notamment de la nature de la base, du rapport molaire collidine-base et du solvant.
- Alpha cinnamomin elicits a defence response against Phytophthora cinnamomi in Castanea sativaPublication . Medeira, C.; Maia, I.; Ribeiro, C.; Candeias, I.; Melo, Eduardo P.; Sousa, N.; Cravador, A.Phytophthora cinnamomi and P. cambivora are considered as the causal agents of Castanea sativa ink disease. These soil-borne plant pathogens invade and destroy the root system leading to the death of the trees. Most Phytophthora species secrete elicitins, a group of unique highly conserved proteins that are able to enhance plant defence responses in a systemic acquired resistance manner against infection by several pathogens. A cluster of four elicitin genes was identified in P. cinnamomi. In previous works one of these elicitins, α- cinnamomin was shown to restrict the invasion of root cortical tissues by P. cinnamomi preventing vascular colonization in cork and holm oak. In the present work, roots of chestnut plantlets grown in vitro were allowed to absorb α-cinnamomin at 100 μg/ml for two days before being inoculated with P. cinnamomi. The effects of this elicitin on host-pathogen interaction were studied at histological and ultrastructural levels. P. cinnamomi was restricted to the outer cortex of 65% of the roots pre-treated with α-cinnamomin. In these roots, the vascular cylinders were free of pathogen. On the contrary, the pathogen reached the vascular cylinder, penetrating the phloem and xylem vessels in all non-treated assayed roots. The signs of pathogen degradation in the cortical parenchyma, mainly in the intercellular spaces, and the increase of a physical barrier in epidermal and sub-epidermal cell wall-media lamella and intercellular spaces by impregnation with phenol-like compounds strongly suggest that α-cinnamomin induced in chestnut defence reactions against P. cinnamomi.
- Analysis of genetic diversity in Portuguese Ceratonia siliqua L. cultivars using RAPD and AFLP markersPublication . Barracosa, Paulo; Lima, M. B.; Cravador, A.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.
- Anti-Phytophthora cinnamomi activity of Phlomis purpurea plant and root extractsPublication . Neves, D.; Caetano, P.; Oliveira, J. V.; Maia, Cristiana; Sousa, N.; Salgado, M.; Dionisio, L.; Magan, N.; Cravador, A.Phlomis purpurea (Lamiaceae), found in Quercus suber and Quercus ilex ssp. rotundifolia forest habitats in southern Portugal, is a non-host for the oomycete Phytophthora cinnamomi, the main biotic factor involved in cork oak and holm oak decline in the Iberian Peninsula. The effect of P. purpurea crude ethanol root extract was evaluated in vitro on P. cinnamomi mycelial growth, sporangial production, zoospore release and germination as well as on chlamydospore production and viability. The protection of cork oak against infection by the pathogen was also evaluated in planta. At 10 mg ml-1, in vitro inhibition of the pathogen structures was 85-100 %. In addition, P. purpurea plants were shown to protect Q. suber and Q. ilex from P. cinnamomi infection and to reduce the inoculum potential in glasshouse trials, indicating the ability to reduce root infection by the pathogen. The results suggest that P. purpurea has the potential to reduce disease spread and that their root extracts could provide candidate substances for control of the important pathogen, P. cinnamomi. © 2013 KNPV.
- Antisense synthtetic DNA [Os DNA sintéticos anti-sentido]Publication . Cravador, A.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.
- Association between SSCPs at Algarvia goat GH and milk traitsPublication . Malveiro, Elisabete; Marques, P. X.; Santos, Ingrid; Belo, Carmona; Cravador, A.The DNA from one hundred eight goats belonging to the indigenous portuguese Algarvia breed was analysed. Single-strand conformation polymorphismÕs (SSCP) were identified at the five exons of the goat Growth Hormone (gGH) gene. Two conformational patterns were found in each of exons 1 and 2, four in exon 3, seven in exon 4 and five in exon 5. The establishment of an association of these SSCP patterns with milk, fat and protein production, and fat and protein content was attempted. Patterns A, F and D of exons 2, 4 and 5, respectively, are positively associated with milk, fat and protein production (p<0.05). Pattern A of exon 2 is also positively associated with fat content (p<0.05).
- Association of milk traits with SSCP polymorphisms at the growth hormone gene in the Serrana goatPublication . Marques, P. X.; Pereira, M.; Marques, MR; Santos, Ingrid; Belo, Carmona; Renaville, Robert; Cravador, A.The present study suggests the existence of an association between milk production traits and genetic polymorphisms at the growth hormone (GH) gene in the Portuguese indigenous Serrana goat. TheDNAfrom 229 animals of two ecotypes (Jarmelista and Ribatejano)was analysed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique revealing a high degree of genetic polymorphism at the goat GH (gGH) gene. Two conformation patterns were detected in exons 1 and 2, 6 in exon 3, 10 in exon 4 and 5 in exon 5. The evaluation of an association effect between these SSCP patterns with milk, fat and protein yields and fat and protein percentages suggests a positive effect of pattern A/B of exon 4 for Ribatejano ecotype and of pattern A/B of exon 2 for Jarmelista ecotype with milk yield (P < 0.05) and of pattern A/B of exon 1 and pattern B/B of exon 2 with protein percentage (P < 0.05) for Ribatejano ecotype. The results support the hints suggested by previous studies of the importance of the gGH gene as a candidate gene for marker-assisted selection in goat breeds and suggest that exon 4 is a preferential target for further investigation on mutations that influence milk yield variation.
- Association of polymorphism of the ß(1, 4)-galactosyltransferase-I gene with milk production traits in HolsteinsPublication . Shahbazkia, Homayon Reza; Aminlari, Mahmoud; Cravador, A.The b(1,4)-galactosyltransferase-I gene (b4galt1) encodes the catalytic part of the enzyme lactose synthase, responsible of lactose synthesis in the mammary gland. The complete coding region of the gene was screened for the presence of allelic variation among a sample of 1,200 Iranian Holstein cows, using PCR-SSCP technique followed by sequencing. Nine polymorphic nucleotide sites were identified- one in exons I and VI, two in exons II and III, and three in exon V. Altogether 18 different genotypes were assigned. Statistical analysis showed that the genotypes of B4GALT1 significantly affect milk, lactose, protein and total solid productions in both the first and second lactation (P\0.001). Variance component analysis considering restricted maximum likelihood showed that the major factor making differences in milk, lactose, protein and total solid productions among the studied cow is the b4galt1 genotype. We concluded that the b4galt1 gene is potentially associated with milk production traits in dairy cows and should be considered for further studies on genetics of the milk production traits.
- Associations among milk production traits and glycosylated haemoglobin in dairy cattle: importance of lactose synthesis potentialPublication . Shahbazkia, Homayon Reza; Aminlari, Mahmoud; Tavasoli, Atoosa; Mohamadnia, Ahmad Reza; Cravador, A.Abstract Glucose is the major precursor of lactose synthesis in the mammary gland. Lactose the major carbohydrate and osmolyte of milk, controls milk volume and its concentration. Glycosylated haemoglobin (HbG) is a retrospective measure of mean blood glucose level and it is largely unaffected by recent physiological conditions and environmental events. The purposes of this study were to determine the correlations between lactose traits and other milk production traits in dairy cattle and to investigate whether HbG level can be correlated with milk and lactose production traits. Here, HbG percentage, milk and lactose production traits including milk yield, lactose, protein, SNF, total solid and fat percentages and yields were measured in 485 second calved Iranian Holstein cattle. Statistically significant negative correlations were established between HbG and milk yield (r=−0.88), lactose yield (r=−0.83), SNF yield (r=−0.81), protein yield (r=−0.79) and total solid yield (r=−0.74). Positive correlations were established between lactose yield and milk (r=0.96), protein (r=0.81), SNF (r=0.92) and total solid (r=0.79) yields. The negative correlation between HbG and milk and total lactose production is probably related to the higher glucose demands in the lactating mammary gland of more productive cows. The positive correlation between lactose yield and milk, protein, SNF and total solid yield indicates that the level of lactose synthesis influences milk production traits in ways other than merely via its osmolytic action.