Differential expression of defence-related proteins in Vigna unguiculata (L. Walp.) seedlings after infection with Fusarium oxysporum

This work aimed to study the induction of defence proteins in cowpea seedlings during the first days after infection with the fungi Fusarium oxysporum f. sp. cubenses and F. oxysporum f. sp. phaseoli. Cowpea seeds, after disinfection, were transferred to Petri dishes containing 0.5% agar and, after germination, were infected with a drop of a suspension containing 0.5 × 10⁴ spores ml⁻¹. Seedlings were collected at 24, 48, 72 and 96 h after infection and were dissected into leaves, hypocotyls, roots, cotyledons and teguments, which were measured and weighed for morphometric analysis. The agar medium was also analyzed. Enzymatic assays of proteic extracts yielded antimicrobial peptides detected by Western blotting. The cowpea seedlings showed a complex pattern of induction and repression of defence proteins in response to infection by both pathogens. Furthermore, morphometric analysis showed differences between infected and control seedlings. Infected samples did not at any time exhibit chitinase activity, but did exhibit different β-1,3-glucanase and peroxidase activities. Western blotting for lipid transfer protein (LTP) demonstrated its presence in all parts of the infected seedlings. Exuded proteins, also obtained from cowpea seeds in the germination medium, were separated by SDS-PAGE and tricine gel electrophoresis. The analysis showed that some proteins were exuded from moistened cowpea seeds, particularly after F. oxysporum infection.     

Environmental influences on post-harvest natural regeneration of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. in Mediterranean forest stands submitted to the seed-tree selection method

Research on natural regeneration is crucial for the development of sustainable forestry practices, in light of the global climate changes taking place. In this study, 151 plots were sampled in six Pinus pinaster stands that were naturally regenerated by the seed-tree method in Mediterranean forests in central Spain. The objectives of the survey were to study the suitability of different forest stands designated for natural regeneration as well as to analyse seedling establishment and the relationship between regeneration and different site factors. Analysis of variance and multivariate analysis with canonical ordination techniques were employed. Full and partial redundancy analyses on a correlation matrix were used to carry out a direct gradient analysis of regeneration density as a function of site factors. Nearly all stands presented seedling densities over 2,000 seedlings ha⁻¹ and were thus found to be suitable for natural regeneration of Pinus pinaster by the seed-tree selection method. Significant variables that best explained total seedling and viable seedling density were spring and autumn precipitation of the year prior to establishment, spring and summer precipitation of the year of establishment and percentage cover of litter. There were no signs of competition between shrubs and seedlings, but a negative significant correlation with grass cover was observed. Pinus pinaster natural regeneration was successful with the seed-tree method, although it appeared to be highly dependent on climate and stand conditions.     

A generalized nonlinear mixed-effects height–diameter model for Eucalyptus globulus L. in northwestern Spain

A generalized height–diameter model was developed for Eucalyptus globulus Labill. stands in Galicia (northwestern Spain). The study involved a variety of pure stands ranging from even-aged to uneven-aged. Data were obtained from permanent circular sample plots in which trees were sampled within different radii according to their diameter at breast height. A combination of weighted regression, to take into account the unequal selection probabilities of such an inventory design, and mixed model techniques, to accommodate local random fluctuations in the height–diameter relationship, were applied to estimate fixed and random parameters for several models reported in the relevant literature. The models that provided the best results included dominant height and dominant diameter as fixed effects. These models explained more than 83% of the observed variability, with mean errors of less than 2.5 m. Random parameters for particular plots were estimated with different tree selection options. Height–diameter relationships tailored to individual plots can be obtained by calibration of the height measurements of the three smallest trees in a plot. An independent dataset was used to test the performance of the model with data not used in the fitting process, and to demonstrate the advantages of calibrating the mixed-effects model.     

Intensification of the Giant river prawn Macrobrachium rosenbergii hatchery production

We evaluated the effect of intensification on Macrobrachium rosenbergii hatchery in clear water recirculating system. Larvae were raised in 120‐L cylindrical tanks coupled with 30‐L biofilters. We performed two experiments in randomized blocks. In the first, we tested the stocking densities of 50, 70 and 90 newly hatched larvae L^?1. Survival did not differ by anova (P = 0.343), but productivity increased with the intensification (P = 0.038). In the second experiment, we tested the stocking densities of 80, 100, 120 and 140 newly hatched larvae L^?1. Survival decreased (P = 0.039) as density increased, but productivity did not differ (P = 0.317). The period of culture ranged from 22 to 23 days. The intensification did not influence water quality parameters or larval development. Survival decreased with the intensification and the space showed to be a limiting factor on tanks stocked with 90 larvae L^?1 or more. Productivity curve shows an increase from 50 to 100 larvae L^?1 and tended to reach plateau on stocking densities higher than 100 larvae L^?1. In addition, the intensification improved the use of Artemia cysts by decreasing the superfluous feeding. Thus, we recommend stocking of 80 to 100 newly hatched larvae L^?1 as the best option for M. rosenbergii hatchery in clear water recirculating system.     

Endocrine disruption in a terrestrial isopod under exposure to bisphenol A and vinclozolin

Background, aim, and scope  

In the past decade there has been an increasing awareness about the possible consequences of human and wildlife exposure to endocrine disrupting compounds (EDCs). Bisphenol A (BPA) and vinclozolin (Vz) are EDCs which impacts on vertebrates have been largely investigated. Nevertheless, research on invertebrate effects, especially on soil organisms, are still largely under-represented. This work aims to extend the limited ecotoxicological datasets available and to provide tools to assess the effects of EDCs on the terrestrial species, using Porcellio scaber (Crustacea: Isopoda) as a model organism.     

Guava decline: effect of root exudates from Meloidogyne enterolobii-parasitized plants on Fusarium solani in vitro and on growth and development of guava seedlings under controlled conditions

In guava decline, Fusarium solani-immune guava trees become susceptible to extensive root rot caused by this fungus after parasitism by Meloidogyne enterolobii. To understand the mechanisms involved in this disease, root exudates were collected from nematode-inoculated (NI) or uninoculated (UN) guava plants cultivated in sand. After filtration through a Millipore® membrane, NI and UN exudates were used: i) to prepare media to assess their effect on mycelial growth and production of propagules of F. solani isolate UENF/CF 163, and ii) to incubate macro- and microconidia to assess their effect on germination. NI exudates promoted (P?<?0.05) more mycelial growth and production of propagules than UN exudates or water. NI and UN exudates were used to water guava seedlings laid over seed germination paper inside plastic boxes. Half of the seedlings had an agar plug colonized by the fungus positioned in the collar region. Upon watering with NI exudates the fungus caused (P?<?0.05) extensive rotting of the seedlings’ rootlets. NI and UN exudates, either unlyophilized or lyophilized and re-suspended to the original concentration, were used to water guava seedlings grown in sterile sand before being inoculated (or left uninoculated) as described before. Solely upon watering with NI exudates, in its unlyophilized form or after lyophilization, the fungus caused a reduction (P?<?0.05) of shoot and root biomass associated with rotting of roots. These results suggest that M. enterolobii induces chemical changes in the root exudates of guava trees, which are necessary for root invasion causing root rotting by F. solani.     

The pyrethroid resistance status and mechanisms in Aedes aegypti from the Guerrero state,Mexico

Dengue is one of the most important vector-borne diseases worldwide and is a public health problem in Mexico. Most programs in dengue endemic countries rely on insecticides for Aedes control. In Mexico, pyrethroid insecticides (mainly permethrin and deltamethrin) have been extensively used over a decade as adulticides and represented a strong selection for insecticide resistance for dengue vectors in several parts of the country. We studied the type, frequency and distribution of insecticide resistance mechanisms in Aedes aegypti from six municipalities in the state of Guerrero selected on the basis of historically intense chemical control and a high risk for dengue transmission. Ae. aegypti eggs were collected from October 2009 to January 2010 using ovitraps. F₁ adults, emerged from these collections, were exposed to permethrin, deltamethrin and DDT in WHO diagnostic tests and showed high resistance levels to both pyrethroids and DDT. This was consistent with the presence of increased metabolic enzyme activities and target site insensitivity due to kdr mutations. Biochemical assays showed elevated esterase and glutathione S-transferase activities in the six municipalities. The V1016I kdr mutation on the IIS6 domain of the sodium channel gene was present in an overall frequency of 0.80. A second mutation, F1534C on the IIIS6 domain of the same gene was also detected, being the first report of this mutation in Guerrero. The multiple resistance mechanisms present in Ae. aegypti from Guerrero state represent a warning for the efficacy of the pyrethroid usage and consequently for the success of the dengue control program.     

Characterization of sulfated quercetin and epicatechin metabolites

Different monosulfates of quercetin and epicatechin with metabolic interest were obtained by hemisynthesis and characterized regarding their chromatographic behavior and absorption and mass spectra. Three of these compounds were further isolated, and their structures were elucidated by mass spectrometry and (1)H and (13)C nuclear magnetic resonance using one- and two-dimensional techniques (heteronuclear single-quantum coherence and heteronuclear multiple-bond correlation). The calculation of the proton and carbon shifts caused by sulfation allowed for the assignment of the position of the sulfate group in the flavonoids, so that the compounds were identified as quercetin-3'-O-sulfate, quercetin 4'-O-sulfate, and epicatechin 4'-O-sulfate. It was found that sulfation at position 3' induced a large upfield shift in the carbon bearing the sulfate group and downfield displacements of the adjacent carbons, whereas no significant upfield or downfield shifts were observed with respect to the parent flavonoid when sulfation was produced at position 4'.     

Quality and aromatic sensory descriptors (mainly fresh and dry fruit character) of Spanish red wines can be predicted from their aroma-active chemical composition

A satisfactory model explaining quality could be built in a set of 25 high quality Spanish red wines, by aroma-active chemical composition. The quality of the wines was positively correlated with the wine content in fruity esters, acids, enolones, and wood derived compounds, and negatively with phenylacetaldehyde, acetic acid, methional, and 4-ethylphenol. Wine fruitiness was demonstrated to be positively related not only to the wine content on fruity esters and enolones, but to wine volatile fatty acids. Fruitiness is strongly suppressed by 4-ethylphenol, acetic acid, phenylacetaldehyde, and methional, this involved in the perception of dry-fruit notes. Sensory effects were more intense in the presence of β-damascenone and β-ionone. A satisfactory model explaining animal notes could be built. Finally, the vegetal character of this set of wines could be related to the combined effect of dimethylsulfide (DMS), 1-hexanol, and methanethiol.     

Prevalence of antibodies against Toxoplasma gondii among Brazilian white-eared opossums (Didelphis albiventris)

Considering that Toxoplasma gondii is a parasite of global importance which affects several animal species including humans, the current study aimed to investigate the prevalence of antibodies against T. gondii among 72 white-eared opossums (Didelphis albiventris) from Botucatu Municipality (22°53'S 48°26'W), S?o Paulo State, Brazil. The investigation was carried out from January 2008 to December 2009, when the animals had their blood samples collected and subjected to the modified agglutination test (MAT); 12 specimens had brain samples bioassayed in mice. Seroprevalence was 5.5% (n=4) and bioassays were negative. Older animals had higher prevalence of antibodies against T. gondii. Opossums in closer contact with the urban environment are likely more exposed to T. gondii than animals from the sylvatic environment.