Evidence for the involvement of ACC deaminase from Pseudomonas putida UW4 in the biocontrol of pine wilt disease caused by Bursaphelenchus xylophilus

Pine wilt disease, caused by the nematode Bursaphelenchus xylophilus, is responsible for devastation of pine forests worldwide. Until now, there are no effective ways of dealing with this serious threat. The use of 1-aminocyclopropane-1-carboxylate (ACC) deaminase (encoded by the acdS gene)-producing plant growth-promoting bacteria has been shown to be a useful strategy to reduce the damage due to biotic and abiotic stresses. Pinus pinaster seedlings inoculated with the ACC deaminase-producing bacterium Pseudomonas putida strain UW4 showed an increased root and shoot development and reduction of B. xylophilus induced symptoms. In contrast, a P. putida UW4 acdS mutant was unable to promote pine seedling growth or to decrease B. xylophilus induced symptoms. This is the first report on the use of ACC deaminase-producing bacteria as a potential biological control agent for a tree disease, thus suggesting that the inoculation of pine seedlings grown in a tree nursery might constitute a novel strategy to obtain B. xylophilus resistant pine trees.     

Glutathione S transferase mu polymorphism and gastric cancer in the Portuguese population

The glutathione S-transferases appear to form part of a protective mechanism against the development of cancer where environmental chemical carcinogens are involved. In humans one member of the mu class gene family (GSTM1) has been shown to be polymorphic and is only expressed in ~50% of individuals. Previous studies have shown a possible link between the null phenotype and susceptibility to cancer but have been equivocal regarding stomach cancer. To evaluate any association in Portuguese gastric cancer individuals with GSTM1 variability, we performed GST M 1 polymorphism by PCR amplification in 148 gastric cancer patients and in 84 healthy control individuals. We found no statistical differences between the gastric cancer and control populations (wild type phenotype: 52%, 48%; null phenotype: 48%, 52%, respectively). A subset analysis into site of tumour also revealed no significant differences between the groups, although we found a slight increase of the wild type phenotype in the samples of the antrum compared with the control population (57% vs 48%, respectively; 2= 1.18; p 0.28) and a slight increase of the null phenotype in the signet ring cells/mucocellular group ( 2= 1.05; p 0.3). However, in both cases it did not reach statistical significance. A subset analysis of the histological groups following the WHO criteria revealed a statistically significant difference ( 2= 3.704; p 0.05) between the moderately differentiated gastric adenocarcinoma and the presence of the wild type phenotype. These results do not support the hypothesis that the GSTM1 null phenotype predisposes to gastric cancer in the Portuguese population and the moderately differentiated gastric adenocarcinoma seems to be associated with the presence of the G STM 1 wild type phenotype.     

A survey of helminth infection in Eurasian badgers (Meles meles) in relation to their foraging behaviour in a Mediterranean environment in southwest Portugal

This study provides the first data on the helminth fauna of the Eurasian badger in the southwestern edge of its range (Grândola Mountain, Portugal) and interprets the results in relation to badger diet and feeding behaviour. By examination of 163 badger faecal samples, faecal developmental stages (eliminative forms) of four helminth species and one genus were identified: one cestode (Atriotaenia incisa) and four nematodes (Mastophorus muris, Molineus patens, Uncinaria criniformis and Strongyloides sp.). The overall prevalence of parasites was 62%, with limited seasonal variation. Single parasite excretions were dominant and Strongyloides sp. excretion was the most common. Diet assessment based on 450 faecal samples revealed that badgers consumed mainly insects and fruits. No correlation was detected between helminth prevalence and diet. Apparently, diet (mainly insects) and feeding behaviour (fossorial), together with the species’ social behaviour (anal scent marking of group members), facilitate the infection with helminths. The helminth fauna of Eurasian badgers in Grândola Mountain has isolationist characteristics, apparently indicating low host colonisation.     

Helicobacter pullorum Isolated from Fresh Chicken Meat: Antibiotic Resistance and Genomic Traits of an Emerging Foodborne Pathogen

Meat and meat products are important sources of human intestinal infections. We report the isolation of Helicobacter pullorum strains from chicken meat. Bacteria were isolated from 4 of the 17 analyzed fresh chicken meat samples, using a membrane filter method. MIC determination revealed that the four strains showed acquired resistance to ciprofloxacin; one was also resistant to erythromycin, and another one was resistant to tetracycline. Whole-genome sequencing of the four strains and comparative genomics revealed important genetic traits within the H. pullorum species, such as 18 highly polymorphic genes (including a putative new cytotoxin gene), plasmids, prophages, and a complete type VI secretion system (T6SS). The T6SS was found in three out of the four isolates, suggesting that it may play a role in H. pullorum pathogenicity and diversity. This study suggests that the emerging pathogen H. pullorum can be transmitted to humans by chicken meat consumption/contact and constitutes an important contribution toward a better knowledge of the genetic diversity within the H. pullorum species. In addition, some genetic traits found in the four strains provide relevant clues to how this species may promote adaptation and virulence.     

S-RNases in apple are expressed in the pistil along the pollen tube growth path

 The molecular bases of self-incompatibility have been intensively studied in a restricted number of model species, but for most families the expression and distribution of S-proteins is unknown. In this work, pistil cryosections from apple were used for in situ detection of S-proteins. Two specific antibodies, one against the S3-protein and another against all apple S-proteins were used. S-proteins were shown to be localised in the intercellular space of the transmitting tissue, both in the stigma and style, which agrees with the proposed mechanism of action for S-RNases in gametophytic self-incompatibility. Some intracellular labelling was also observed in all ovary sections, confined to one layer of the nucellus surrounding the embryo sac, but this labelling was found to be non-S-allele-specific. Nevertheless, the signal in the ovary was tissue-specific, which may indicate that some component not encoded by the S-locus but similar to S-proteins was detected. To the best of our knowledge this is the first report on the precise distribution of S-RNases in a rosaceous species. Received: 15 July 1998 / Revision accepted: 29 December 1998     

Stone marten (Martes foina) habitat in a Mediterranean ecosystem: effects of scale, sex, and interspecific interactions

Mediterranean ecosystems are inherently patchy, challenging habitat-use behavior. Certain mammalian carnivores take advantage of this patchiness by a strategy of habitat complementation/supplementation, which is invariant to the scale of analysis. To test if the same behavior is adopted by the stone marten, we used a combined data set of capture and radio-tracking data at three scales of analysis (1-m, 25-m, and 452-m radius plots). We used compositional analysis to test if there were sex-specific differences in foraging and resting habitat use of stone martens and if these patterns were affected by the presence of other mesocarnivores. Our results showed that stone martens are found both in rural and forested landscapes. Foraging and resting activities occurred far from roads in large and complex patches of cork oak woodlands, riparian vegetation, orchards, and pastureland. Use varied with the scale of analysis and the sex. At smaller scales, females use pastures for foraging and orchards for resting, whereas riparian vegetation and sparse cork oak forests influenced this use at larger scales. Males, on the other hand, were more consistent across scales, using riparian areas and dense cork oak woodlands for foraging and pastures for resting. Stone martens shared the same areas with other coexisting mesocarnivores. Stone martens use cork oak woodlands and complement/supplement this use with other land cover types. The consistent use of cork oak woodlands across scales emphasizes the importance of this land cover to the preservation of functional Mediterranean ecosystems in southern Portugal.     

Somatic embryogenesis induction in leaves and petioles of a mature wild olive

We describe a protocol for somatic embryogenesis (SE) induction from an adult wild olive tree (Olea europaea ssp. europaea var. sylvestris. The protocol used confirms for the first time that there is no need to use juvenile or rejuvenated material for SE induction. For SE induction, petiole and leaf (proximal, intermediary and distal zones) explants were grown on Murashige and Skoog (MS) or Olive Medium (OM) media with different combinations of plant growth regulators (PGR): α- naphthaleneacetic acid (NAA), Zeatin (Zea), indole-3-butyric acid (IBA), 2-isopentyl adenine (2iP), thidiazuron (TDZ) and 6-benzylaminopurine (BAP). All media had 30 g/l sucrose and 7 g/l agar, and the pH was adjusted to 5.8. Cultures were incubated in the dark and, after 3 months, they were transferred to MS medium without PGR for expression. Petiole explants gave the highest callus production, while for SE induction and expression distal blade leaf and petiole explants gave the highest rates. The best medium for SE induction was MS with 12.25 μM IBA plus 4.56 μM Zea. Histological analyses confirmed the individuality of globular somatic embryos. This is the first report of SE expression in explants without rejuvenation in Olea genus, and opens perspectives for using this strategy in SE protocols both for this wild genotype and for commercial genotypes.