Decline of Mediterranean oak trees and its association with Phytophthora cinnamomi: a review     

Constança de Sampaio e Paiva Camilo-Alves  Maria Ivone Esteves da Clara  Nuno Manuel Cabral de Almeida Ribeiro 《European Journal of Forest Research》2013,132(3):411-432

Mortality events in cork and holm oaks have occurred in the Mediterranean basin since the beginning of the XX century, but severity of decline increased during the 1980s. By that time, the exotic soil borne pathogen Phytophthora cinnamomi was often recovered from declining stands and since then it has been considered the main factor associated with decline. This work analyses data concerning P. cinnamomi surveys in cork and holm oaks trees, pathogenicity tests carried out in controlled experiments, studies about the influence of site characteristics in tree decline and approaches to control the disease. Results of field surveys showed that the pathogen is widespread and pathogenicity tests suggested that host susceptibility to the pathogen is moderate when seedlings are in appropriate watering conditions, particularly cork oaks. Occurrence of decline is also associated with soil characteristics that interfere with root expansion and water retention. We assessed the relative importance of each factor involved in decline and revised the role of P. cinnamomi in cork and holm oak decline.  相似文献   

Genomic Description of Antibiotic Resistance in Escherichia coli and Enterococci Isolates from Healthy Lusitano Horses     

Inês Moura  Carmen Torres  Nuno Silva  Sergio Somalo  Gilberto Igrejas  Patrícia Poeta 《Journal of Equine Veterinary Science》2013

Antibiotic resistance is a global problem, and it is known that commensal bacteria can act as reservoir of antibiotic resistance genes of clinical importance. The aim of the present study was to determine the antibiotic resistance phenotype and mechanisms implicated in resistance of Escherichia coli and Enterococcus spp. isolates collected from fecal samples of 90 Lusitano horses from Portugal. Sixteen of the 71 E. coli isolates (22.5%) recovered showed resistance to at least one of the antibiotics tested. The number of E. coli isolates resistant to streptomycin, tetracycline, chloramphenicol, ampicillin, trimethoprim-sulfamethoxazole, and gentamicin was 9, 7, 6, 3, 2, and 1, respectively. The bla_TEM-1 and bla_OXA-1 genes were detected in ampicillin-resistant isolates and the sul2 and dfrA1 genes in trimethoprim-sulfamethoxazole-resistant, while the aac(3)-I, floR and tet(A) were found in the gentamicin, chloramphenicol and tetracycline-resistant isolates, respectively. Twenty-two of the 71 (31%) recovered enterococci showed antibiotic resistance for at least one of the tested antibiotics, and resistant isolates were identified as Enterococcus faecium (n = 14), E. faecalis (n = 3), E. hirae (n = 2), and Enterococcus spp. (n = 3). The erm(B) and erm(C) genes were identified in erythromycin-resistant enterococci and the tet(M) and/or tet(L) genes in tetracycline-resistant isolates. The slight prevalence of antibiotic resistance among commensal bacteria of healthy Lusitano horses can improve the treatment of upcoming infections in these horses because these microorganisms can be considered as antimicrobial indicator bacteria.  相似文献   

Biological Activities and Chemical Composition of Methanolic Extracts of Selected Autochthonous Microalgae Strains from the Red Sea     

Hugo Pereira  Luísa Custódio  Maria Jo?o Rodrigues  Carolina Bruno de Sousa  Marta Oliveira  Luísa Barreira  Nuno da Rosa Neng  José Manuel Florêncio Nogueira  Salman A. Alrokayan  Fouzi Mouffouk  Khalid M. Abu-Salah  Radhouan Ben-Hamadou  Jo?o Varela 《Marine drugs》2015,13(6):3531-3549

Four lipid-rich microalgal species from the Red Sea belonging to three different genera (Nannochloris, Picochlorum and Desmochloris), previously isolated as novel biodiesel feedstocks, were bioprospected for high-value, bioactive molecules. Methanol extracts were thus prepared from freeze-dried biomass and screened for different biological activities. Nannochloris sp. SBL1 and Desmochloris sp. SBL3 had the highest radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl, and the best copper and iron chelating activities. All species had potent butyrylcholinesterase inhibitory activity (>50%) and mildly inhibited tyrosinase. Picochlorum sp. SBL2 and Nannochloris sp. SBL4 extracts significantly reduced the viability of tumoral (HepG2 and HeLa) cells with lower toxicity against the non-tumoral murine stromal (S17) cells. Nannochloris sp. SBL1 significantly reduced the viability of Leishmania infantum down to 62% (250 µg/mL). Picochlorum sp. SBL2 had the highest total phenolic content, the major phenolic compounds identified being salicylic, coumaric and gallic acids. Neoxanthin, violaxanthin, zeaxanthin, lutein and β-carotene were identified in the extracts of all strains, while canthaxanthin was only identified in Picochlorum sp. SBL2. Taken together, these results strongly suggest that the microalgae included in this work could be used as sources of added-value products that could be used to upgrade the final biomass value.  相似文献   

Comprehensive diversity assessment of walnut-associated xanthomonads reveal the occurrence of distinct Xanthomonas arboricola lineages and of a new species (Xanthomonas euroxanthea) within the same tree     

Camila Fernandes  Pedro Albuquerque  Nuno Mariz-Ponte  Leonor Cruz  Fernando Tavares 《Plant pathology》2021,70(4):943-958

Xanthomonas arboricola pv. juglandis (Xaj) is the aetiological agent of walnut diseases causing economic losses on walnut production worldwide. This phytopathogen is spread around the world where walnuts are produced and has a considerable genetic diversity. Using a comprehensive sampling methodology, focusing on factors that could influence the diversity of walnut-colonizing Xaj in Portugal, this work provides new insights on xanthomonad populations on walnut. Genetic diversity was assessed by multilocus sequence analysis (MLSA) and dot blot hybridization patterns on 131 Xanthomonas isolates obtained from 64 walnut trees considering epidemiological metadata such as year of isolation, distinct bioclimatic regions, production regimes, and host-related features. The results showed that the majority of isolates were split into 17 lineages of Xaj, while the other isolates clustered in four MLSA groups that did not include Xaj strains. These four groups were represented by three lineages of X. arboricola, and 11 lineages of Xanthomonas spp., including strains assigned to the recently proposed new species Xanthomonas euroxanthea. Furthermore, distinct Xaj, X. arboricola, and Xanthomonas spp. were isolated from the same walnut tree, suggesting possible genetic admixture within the same host. Phylogenetic analysis through geoBurst revealed the high diversity of these Xanthomonas spp. populations. Assessment of type III effector genes gave the indication that some Xanthomonas spp. strains were nonpathogenic on walnut, with the exception for X. euroxanthea CPBF 424. Altogether, these findings add to the thorough characterization of walnut-associated xanthomonads in Portugal, providing a comprehensive snapshot of the current diversity that could contribute to risk assessment analysis and improve phytosanitary control.  相似文献   

Genetic parameters and comparison between native and local landraces of Eucalyptus globulus Labill. ssp. globulus growing in the central highlands of Colombia     

Martha Salas  Víctor Nieto  Liliana Perafán  Alejandro Sánchez  Nuno M. G. Borralho 《Annals of Forest Science》2014,71(3):405-414

Aims

The objective of this study was to compare the merit of the Colombian landrace relative to the various Australian native races of Eucalyptus globulus Labill. ssp. globulus and study the genetic control of key traits such as growth, wood density, and leaf phase change in the unique conditions of the Colombian highlands.

Methods

The genetic study was based on open-pollinated families from native Australian and Colombian landrace origin, tested across four trials spanning two generations of breeding. A multisite mixed linear model with genetic groups was fitted to the data to estimate race merit and the variance and covariances between traits, ages, and sites.

Results

Race effects for growth were small and only significant at the older site. In contrast, races differ significantly for height to phase change and density. The Colombian landrace and South and NE Tasmania races changed leaf type at a higher tree height. King Island and Recherche Bay had low density values, whereas the Colombian landrace had the highest. Heritability was moderate for growth traits (between 0.09 and 0.40), high for height to phase change (between 0.42 and 0.69), and moderate for wood density (0.28). The genetic correlation between growth and height to phase change was in general positive, but variable across sites. There was no correlation between growth and density. Despite large differences in growth between trials, pairwise genetic correlations suggest that genotype-by-site interaction is negligible. However, there was a poor correspondence between first-generation (ex-native stands) and second-generation families (ex-multi-provenance progeny trial). This suggests that breeding value estimates based on native open-pollinated material are unreliable.

Conclusion

Results confirm negligible race differences for growth, but not for wood density. Future breeding efforts should include the various genetic backgrounds including the Colombian landrace which constitutes a very important source, especially because of its high density. Despite a low Genotype by Environment interaction, the poor genetic correspondence between the first- and second-generation trials indicates that selections for growth should be based on information coming mainly from the advanced-generation trials.  相似文献   

Toxic effects of molluscicidal baits to the terrestrial isopod <Emphasis Type="Italic">Porcellionides pruinosus</Emphasis> (Brandt, 1833)     

Miguel João G. Santos  Nuno G. C. Ferreira  Amadeu M. V. M. Soares  Susana Loureiro 《Journal of Soils and Sediments》2010,10(7):1335-1343

Purpose  

Methiocarb and metaldehyde are the most common molluscicides applied in agricultural and horticultural fields in Portugal and elsewhere in Europe. The application of molluscicidal baits to control slug and snail populations can pose a threat to non-target organisms like terrestrial isopods, because they are detritivorous and may feed on the toxic baits applied to the soil surface. The aim of this work was to evaluate the effects and understand the modes of action of these molluscicides to terrestrial isopods.  相似文献   

Basal levels of enzymatic biomarkers and energy reserves in Porcellionides pruinosus     

Nuno G.C. Ferreira  Miguel J.G. Santos  Inês Domingues  Carla F. Calhôa  Marta Monteiro  Mónica J.B. Amorim  Amadeu M.V.M. Soares  Susana Loureiro 《Soil biology & biochemistry》2010,42(12):2128-2136

In the last decades biomarkers have been widely used for the assessment of effects and/or exposure to environmental contaminants, but to our knowledge few data has been published for isopod species. Along with biomarkers the quantification of energy reserves has also been used to evaluate organisms’ energetic budget. Enzymatic biomarkers can also be useful to understand chemicals/stress modes of action. The aim of this study was to obtain information on biomarker basal level activities and energy contents of the isopod Porcellionides pruinosus as little information is available. Results can then be used as foundations for other ecotoxicological or biomonitorization studies and also as control values for evaluating isopod status in laboratory cultures.The cholinesterase (ChE) type of the isopod P. pruinosus was characterized using three substrates (acetylthiocholine iodide, propionylthiocholine iodide, and S-butyrylthiocholine iodide) and three ChE inhibitors (eserine hemisulfate, tetraisopropyl pyrophosphoramide (iso-OMPA) and 1,5-bis(4-allyldimethyl-ammonimphenyl) pentan-3-one dibromide (BW284C51)]. The results showed that this organism has only one cholinesterase form, the acetylcholinesterase with a mean basal level of 113.6 ± 4.7 U/mg protein.Other biomarkers related to oxidative stress or metabolism were assessed, showing activity ranges of 3.0 ± 1.1 U/mg protein for lactate dehydrogenase (LDH), 6.1 ± 1.1 U/mg protein for catalase (CAT), 2.7 ± 1.1 U/mg protein for glutathione peroxidase (GPx), 34.6 ± 4.7 nmol/mg ww for lipid peroxidation (LPO) and 137.8 ± 7.1 U/mg protein for glutathione S-transferases (GST) (mean ± st. error). The carbohydrates and protein contents were 12290.8 ± 56.4 J/mg organism (org) and 22905 ± 57.5 J/mg org, respectively (mean ± st. error). The mean lipid content was 503.1 ± 12.7 J/mg org.Our results were compared to other previous works with isopod species but also with other species, showing high levels of inter and intraspecific variability. Even tough this study can contribute as foundations for other studies as ChE characterization, optimization of homogenization procedures and basal levels for biomarker activity and energy reserves were described.  相似文献   

Artificial insemination of cows with semen in vitro contaminated with Neospora caninum tachyzoites failed to induce neosporosis     

Canada N  Meireles CS  Ferreira P  Correia da Costa JM  Rocha A 《Veterinary parasitology》2006,139(1-3):109-114

Neosporosis is a major cause of abortion in cattle all over the world. Congenital transmission as well as horizontal transmission by ingestion of oocysts has been described. The detection of Neospora caninum DNA in bull semen warrants the investigation of possible transmission through the use of contaminated semen. In this experiment four cows were artificially inseminated with frozen-thawed semen contaminated in vitro with viable N. caninum tachyzoites (group A) and four control cows were inseminated with tachyzoites-free frozen-thawed semen, from the same bull (group B). Serum samples were collected 15 days before the artificial insemination (AI) and at days 10, 14, 21, 28, 45, 60 and 75 post-insemination. All sera samples were tested for neosporosis by direct agglutination test (DAT). Three of the cows from group A had negative DAT titers (< or =1:20) in all of the samples, while the fourth cow from this group had a low titer of antibodies (1:80) at day 10, and became negative at day 45, suggesting a stimulation of the immune system by the tachyzoites placed in uterus, rather than the induction of an infection. All of the cows from group B had negative DAT titers (< or =1:20) in all of the samples. These results suggest that transmission of neosporosis by artificial insemination with frozen-thawed semen is an unlikely event.  相似文献   

Interaction of different polyphenols with bovine serum albumin (BSA) and human salivary alpha-amylase (HSA) by fluorescence quenching   总被引：1，自引：0，他引：1  

Soares S  Mateus N  Freitas Vd 《Journal of agricultural and food chemistry》2007,55(16):6726-6735

Phenolic compounds are responsible for major organoleptic characteristics of plant-derived food and beverages; these substances have received much attention, given that the major function of these compounds is their antioxidant ability. In the context of this study, our major aim was study the binding of several phenolic compounds such as (+)-catechin, (-)-epicatechin, (-)-epicatechin gallate, malvidin-3-glucoside, tannic acid, procyanidin B4, procyanidin B2 gallate, and procyanidin oligomers to different proteins (bovine serum albumin and human alpha-amylase) by fluorescence quenching of protein intrinsic fluorescence. From the spectra obtained, the Stern-Volmer, the apparent static, and the bimolecular quenching constants were calculated. The structure of polyphenols revealed to significantly affect the binding/quenching process; in general, the binding affinity increased with the molecular weight of polyphenol compounds and in the presence of galloyl groups. For catechin monomer and procyanidin dimer B4, the K(SV) was 14,100 and 13,800 M(-1), respectively, and for galloyl derivatives, the K(SV) was 19,500 and 21,900 M(-1), respectively. Tannic acid was shown to be the major quenching molecule for both proteins. However, comparing different proteins, the same polyphenol showed different quenching effects, which are suggested to be related to the three-dimensional structure of the proteins studied. For (+)-catechin and BSA, the K(SV) was 8700 M(-1), and with alpha-amylase, it was 14,100 M(-1); for tannic acid, the K(SV) was 10,0548 and 11,0674 M(-1), respectively. From the results obtained, besides the main binding analysis performed, we conclude that this technique is more sensitive than thought because we can detect several interactions that have not been proven by other methods, namely, nephelometry. Overall, fluorescence quenching has proven to be a very sensitive technique with many potentialities to analyze the interaction between polyphenols and proteins.  相似文献   

Detection of Ehrlichia canis by polymerase chain reaction in dogs from Portugal     

Alexandre N  Santos AS  Núncio MS  Sousa Rd  Boinas F  Bacellar F 《Veterinary journal (London, England : 1997)》2009,181(3):343-344

Antibodies against Ehrlichia canis, the cause of canine monocytic ehrlichiosis, have been reported previously in clinically ill and stray dogs from Portugal. In this study, the 16S rRNA gene of E. canis was detected by the polymerase chain reaction (PCR) in 12/55 (22%) of dogs with suspected tick-borne disease in the Algarve region in Portugal.  相似文献