An improved protocol for electrotransformation of Corynebacterium pseudotuberculosis

We developed an improved protocol for the electrotransformation of Corynebacterium pseudotuberculosis, testing variations of parameters in the procedures that are routinely used for the preparation of electrocompetent cells of this species, including (i) culture conditions, (ii) cell growth phase, (iii) electroporation solutions and (iv) quantity of plasmid DNA. We obtained the greatest efficiency of transformation when the cells were grown until the stationary phase and then washed with 10% glycerol electroporation solution. The transformation efficiency was inversely proportional to the quantity of plasmid DNA. The transformation efficiency reached 10(5) colony-forming units (cfu)/mug plasmid DNA. This protocol would be useful for genetic studies of C. pseudotuberculosis.     

Oleoresin yield of Pinus elliottii plantations in a subtropical climate: Effect of tree diameter, wound shape and concentration of active adjuvants in resin stimulating paste

The production of oleoresin from Pinus trees is a relevant economic activity in developing countries, since it provides terpenes used in the chemical industry. The oleoresin production by trees of Pinus elliottii in southern Brazil was investigated. Trees of approximately 28 years of age were individually analyzed for oleoresin yield using the bark streak method of wounding for resin tapping. Plain wounding and wounding followed by application of commercial resin stimulant paste, composed of an ethylene precursor (CEPA) and sulphuric acid, were used as reference treatments. The optimum concentrations of CEPA and sulphuric acid in the stimulant paste were investigated in relation to oleoresin yield, as well as the shape of wound and tree diameter. The replacement of CEPA with auxin in the resin stimulant paste was also evaluated. The results showed that both horizontal and V-shaped streaks are equivalent for oleoresin yield. Trees with larger diameter at breast height, defined as the trunk diameter 1.4 m above the ground (22–23.5 cm) yielded more oleoresin than their smaller counterparts (18–19.5 cm). Oleoresin yield was equivalent with stimulant pastes containing between 1.5 and 4.5% CEPA. Trees exposed to stimulant pastes containing from 3 to 4.5% CEPA had average year oleoresin yield above 5 kg. The use of 20% sulphuric acid in the stimulant paste resulted in higher oleoresin yields. Auxin (2,4-D at 1 mM) was effective in replacing CEPA in the stimulant paste, particularly in smaller DBH trees or after 1 year of application in larger DBH individuals. In conclusion, cost reductions on resin tapping can be achieved by adjusting stimulant paste components and managing subsets of trees in specific fashion based on DBH ranges.     

Efficiency of low heritability QTL mapping under high SNP density

The efficiency of quantitative trait locus (QTL) mapping methods needs to be investigated assuming high single nucleotide polymorphism (SNP) density and low heritability QTLs. This study assessed the efficiency of the least squares, maximum likelihood, and Bayesian approaches for QTL mapping assuming high SNP density and low heritability QTLs. We simulated 50 samples of 400 F₂ individuals, which were genotyped for 1000 SNPs (average density of one SNP/centiMorgan) and phenotyped for three traits controlled by 12 QTLs and 88 minor genes. The genes were randomly distributed in the regions covered by the SNPs along ten chromosomes. The QTL heritabilities ranged from approximately 1–2% and the sample sizes were 200 and 400. The power of QTL detection ranged from 30 to 60%, the false discovery rate (FDR) ranged from only 0.5–1.2%, and the bias in the QTL position ranged from 4 to 6 cM. The QTL mapping efficiency was not influenced by the degree of dominance. The statistical approaches were comparable regarding the FDR. Regression-based and simple interval mapping methods showed equivalent power of QTL detection and mapping precision. Compared to interval mapping, the inclusive composite interval mapping provided slightly greater QTL detection power and mapping precision only for the intermediate and high heritability QTLs. By maximizing the prior number of QTLs, the Bayesian analysis provided the greatest power of QTL detection. No method proved to be superior.     

Impact of global warming on cowpea bean cultivation in northeastern Brazil

This study evaluated the effects of climate change on cowpea bean crop grown in northeastern Brazil based on the reports of the Intergovernmental Panel on Climate Change (IPCC). The water balance model combined with Geographic Information System techniques was used to identify regional areas where the cowpea bean crop will suffer yield reduction due to climate changes. Model input variables were: rainfall, crop coefficients, potential evapotranspiration and duration of the crop cycle. A limit value of 0.5 was adopted for the water requirement satisfaction index (WRSI), being the ratio of actual to maximum evapotranspiration. The acceptable seeding date was defined as the date at which the water balance simulation presented a WRSI value greater than the limit value, with a frequency of at least 80%. An increase in air temperature will cause a significant reduction in the areas currently favorable to cowpea bean crop growth in northeastern Brazil, and it is recommended that bean varieties better suited to high-temperature conditions should be planted.     

Neotropical freshwater fishes imperilled by unsustainable policies

Neotropical freshwater fishes are the most diverse on the planet (>5,500 species), although nations in Latin America have been negligent regarding their conservation. National policies have historically encouraged unsustainable practices, and recent decades have witnessed a sharp increase in harmful activities. Our aim with this review was to expose this situation and illustrate how national policies constitute the main threat to freshwater fish biodiversity. We explain that the most devastating, pervasive and systemic threats are rooted in official policies, particularly unsustainable activities (e.g. hydropower, water diversion, mining, aquaculture, agriculture and fishing), poor management/conservation (e.g. fish stocking and passages) and harmful legislation (e.g. poor licensing, non‐native species). We provide a broad portrait of the Neotropical scenario, where unsustainable policies have caused considerable damage to freshwater ecosystems, and focus on major examples from Brazil, where development projects have caused large‐scale losses to fish biodiversity. Such modus operandi of human development is incompatible with the persistence of biodiversity, and no simple solution is available to correct or minimize its effects. The current situation demands a profound behavioural shift towards better practices and policies, or these multiple high‐impact activities will continue eroding freshwater fish biodiversity and impairing essential ecosystem services.     

Sweet passion fruit yield and fruit quality related to fertilization with urea and cattle manure

An experiment was conducted in Campos dos Goytacazes in the State of Rio de Janeiro, Brazil, in order to evaluate the applying effect of nitrogen and cattle manure doses on sweet passion fruit yield and quality. The experimental outline used was complete block, in a 5 × 2 factorial arrangement, five nitrogen doses (0, 50, 150, 250 and 350g plant^?1 year^?1) and two types of organic fertilization (with and without cattle manure), with 4 replications. Sweet passion fruit yield presented an increase of 44.4% due to the application of the best nitrogen doses in comparison with the treatment which did not receive nitrogen fertilization. The treatments that did not receive cattle manure presented higher average weight, diameter and thickness of the fruit skin, while the addition of cattle manure presented greater juice concentration and higher percentage of seeds in sweet passion fruit fruits. The increase in nitrogen doses allowed an increase in concentration and total titratable acidity of the fruits.     

First report of an insect pest on Passiflora tenuifila Killip (Passifloraceae)

The genus Passiflora L. has more than 400 species, most of which occur natively in tropical and subtropical regions of South America. The fruit of Passiflora tenuifila Killip, one of the native species of Brazil, has great potential for commercial use by pharmaceutical and cosmetic industries, due to its high content of phenolic compounds, which are natural antioxidants. The study was conducted in two areas located in Tocantins and in the Federal District, Brazil. The presence of globose lumps and thickening of the stems on plants of Pa. tenuifila was observed on plants in these areas. Injured samples taken from both locations were analyzed and showed the presence of larvae and pupae of a Curculionidae, which completed their life cycle in the laboratory. The adults were identified as Philonis crucifer (Brèthes) (Coleoptera: Curculionidae). In Tocantins, 100% of the plants in the trial area were infested, while in the Federal District trial the incidence of infestation was 20.3%. This is the first report of an insect on Pa. tenuifila, indicating the need to develop management strategies for this pest to be applied in commercial crops of this Passiflora species.     

New gastropod vectors and tetrodotoxin potential expansion in temperate waters of the Atlantic Ocean

Tetrodotoxin is a potent low weight marine toxin found in warm waters, especially of the Indian and Pacific Oceans. Intoxications are usually linked to the consumption of the puffer fish, although TTX was already detected in several different edible taxa. Benthic organisms such as mollusks and echinoderms, with different feeding habits, were collected monthly along the Portuguese coast from the summer of 2009 until the end of 2010. The extraction and analysis techniques were optimized and TTX and some analogues were detected for the first time in two intertidal gastropod species-Gibbula umbilicalis and Monodonta lineata by LC-MS/MS and UPLC-MS/MS. Although the levels are low, these findings suggest that monitoring of TTX and analogues in North Atlantic species should be implemented so as to detect potentially new toxin vectors and seasonal and/or geographical patterns.