Inhibition of Alternaria stem canker on tomato by essential oils from Baccharis species

Abstract

The toxicity of four essential oils extracted from Baccharis articulata, Baccharis ochracea, Baccharis psiadioides and Baccharis trimera was tested against the phytopathogen Alternaria alternata, which causes Alternaria stem canker on tomatoes. Diseases caused by Alternaria fungi are responsible for great economic losses in terms of production and are controlled by synthetic fungicides; however, essential oils offer an alternative, since they have been proven to be effective for controlling against various plant pathogens. In this way, the antifungal activity of Baccharis essential oils was tested using potato dextrose agar medium with concentrations ranging from 0.1 to 20.0?µL mL^?1. Baccharis trimera and Baccharis ochracea essential oils presented 100% mycelial growth inhibition of A. alternata and were also able to control Alternaria stem canker disease under greenhouse conditions. Tomato plants treated with these essential oils exhibited area under the disease progress curve (AUDPC) values of 230.10 and 241.42, differing from the control condition, which showed an AUDPC value of 268.92. The essential oils of B. trimera and B. ochracea can be an alternative for controlling Alternaria stem canker disease of tomatoes and should be formulated as a potential fungicide against the A. alternata pathogen.     

Sunlight-induced degradation of soil-adsorbed veterinary antimicrobials Marbofloxacin and Enrofloxacin

Marbofloxacin (MAR) and Enrofloxacin (ENR), two largely employed veterinary Fluoroquinolones (FQs), were found to be present at the micrograms per kilogram level in agricultural soils of South Lombardy (Italy) several months after manuring. Distribution coefficients (K_d) from sorption experiments indicated a strong binding to the soil. Soil samples fortified with environmentally significant FQs amounts (0.5 mg kg⁻¹) were exposed to solar light that promoted extensive degradation (80%) of both drugs in 60-150 h. Thus, photochemistry could be considered a significant depollution path in the soil, although it was two orders of magnitudes slower than in aqueous solution and a fraction of the drug (ca. 20%) remained unaffected. For MAR the photoprocess was the same as in solution, and involved cleavage of the tetrahydrooxadiazine ring. On the contrary, with ENR only some of the photoproducts determined in water (those arising from a stepwise oxidation of the piperazine side chain) were observed. Substitution of the 6-fluoro by a hydroxyl group and reduction did not occur in the soil, supporting the previous contention that such processes required polar solvation of FQs. Consistently with this rationalization, the irradiation of thin layers of solid drugs led to essentially the same products distribution as in the soil. From the environmental point of view it is important to notice that photodegradation mainly affects the side-chains, while the fluoroquinolone ring, to which the biological effect is associated, is conserved up to the later stages of the degradation.     

Mercury, lead and cadmium in human milk in relation to diet, lifestyle habits and sociodemographic variables in Madrid (Spain)

Background

Although breastfeeding is the ideal way of nurturing infants, it can be a source of exposure to toxicants. This study reports the concentration of Hg, Pb and Cd in breast milk from a sample of women drawn from the general population of the Madrid Region, and explores the association between metal levels and socio-demographic factors, lifestyle habits, diet and environmental exposures, including tobacco smoke, exposure at home and occupational exposures.

Methods

Breast milk was obtained from 100 women (20 mL) at around the third week postpartum. Pb, Cd and Hg levels were determined using Atomic Absorption Spectrometry. Metal levels were log-transformed due to non-normal distribution. Their association with the variables collected by questionnaire was assessed using linear regression models. Separate models were fitted for Hg, Pb and Cd, using univariate linear regression in a first step. Secondly, multivariate linear regression models were adjusted introducing potential confounders specific for each metal. Finally, a test for trend was performed in order to evaluate possible dose-response relationships between metal levels and changes in variables categories.

Results

Geometric mean Hg, Pb and Cd content in milk were 0.53 μg L⁻¹, 15.56 μg L⁻¹, and 1.31 μg L⁻¹, respectively. Decreases in Hg levels in older women and in those with a previous history of pregnancies and lactations suggested clearance of this metal over lifetime, though differences were not statistically significant, probably due to limited sample size. Lead concentrations increased with greater exposure to motor vehicle traffic and higher potato consumption. Increased Cd levels were associated with type of lactation and tended to increase with tobacco smoking.

Conclusions

Surveillance for the presence of heavy metals in human milk is needed. Smoking and dietary habits are the main factors linked to heavy metal levels in breast milk. Our results reinforce the need to strengthen national food safety programs and to further promote avoidance of unhealthy behaviors such as smoking during pregnancy.     

Prenatal diagnosis,prediction of outcome and in utero therapy of isolated congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) can be associated with genetic or structural anomalies with poor prognosis. In isolated cases, survival is dependent on the degree of lung hypoplasia and liver position. Cases should be referred in utero to tertiary care centers familiar with this condition both for prediction of outcome as well as timed delivery. The best validated prognostic indicator is the lung area to head circumference ratio. Ultrasound is used to measure the lung area of the index case, which is then expressed as a proportion of what is expected normally (observed/expected LHR). When O/E LHR is < 25% survival chances are < 15%. Prenatal intervention, aiming to stimulate lung growth, can be achieved by temporary fetal endoscopic tracheal occlusion (FETO). A balloon is percutaneously inserted into the trachea at 26–28 weeks, and reversal of occlusion is planned at 34 weeks. Growing experience has demonstrated the feasibility and safety of the technique with a survival rate of about 50%. The lung response to, and outcome after FETO, is dependent on pre-existing lung size as well gestational age at birth. Early data show that FETO does not increase morbidity in survivors, when compared to historical controls. Several trials are currently under design. Copyright © 2008 John Wiley & Sons, Ltd.     

Bird‐community responses to habitat creation in a long‐term,large‐scale natural experiment

Ecosystem function and resilience are compromised when habitats become fragmented due to land‐use change. This has led to national and international conservation strategies aimed at restoring habitat extent and improving functional connectivity (i.e., maintaining dispersal processes). However, biodiversity responses to landscape‐scale habitat creation and the relative importance of spatial and temporal scales are poorly understood, and there is disagreement over which conservation strategies should be prioritized. We used 160 years of historic post‐agricultural woodland creation as a natural experiment to evaluate biodiversity responses to habitat creation in a landscape context. Birds were surveyed in 101 secondary, broadleaf woodlands aged 10–160 years with ≥80% canopy cover and in landscapes with 0‐17% broadleaf woodland cover within 3000 m. We used piecewise structural equation modeling to examine the direct and indirect relationships between bird abundance and diversity, ecological continuity, patch characteristics, and landscape structure and quantified the relative conservation value of local and landscape scales for bird communities. Ecological continuity indirectly affected overall bird abundance and species richness through its effects on stand structure, but had a weaker influence (effect size near 0) on the abundance and diversity of species most closely associated with woodland habitats. This was probably because woodlands were rapidly colonized by woodland generalists in ≤10 years (minimum patch age) but were on average too young (median 50 years) to be colonized by woodland specialists. Local patch characteristics were relatively more important than landscape characteristics for bird communities. Based on our results, biodiversity responses to habitat creation depended on local‐ and landscape‐scale factors that interacted across time and space. We suggest that there is a need for further studies that focus on habitat creation in a landscape context and that knowledge gained from studies of habitat fragmentation and loss should be used to inform habitat creation with caution because the outcomes are not necessarily reciprocal.     

Spatial and temporal variability of water quality in the coral reefs of Tayrona National Natural Park,Colombian Caribbean

Tayrona National Natural Park (TNNP) is a hotspot of coral reef biodiversity in the Colombian Caribbean, located between the city of Santa Marta (>455,000 inhabitants) and several smaller river mouths (Rio Piedras, Mendihuaca, Guachaca). The region also experiences a strong seasonal variation in physical parameters (temperature, salinity, wind, and water currents) due to alternating dry seasons with coastal upwelling and rainy seasons. However, the spatial and temporal effects on water quality parameters relevant for coral reef functioning have not been investigated. Therefore, inorganic nutrient, chlorophyll a, and particulate organic carbon (POC) concentrations along with biological O₂ demand (BOD), pH, and water clarity directly above local coral reefs (~10 m water depth) were monitored for 25 months in four bays along a distance gradient (12–20 km) to Santa Marta in the southwest and to the first river mouth (17–27 km) in the east. This is by far the most comprehensive coral reefs water quality dataset for the region. Findings revealed that particularly during non-upwelling, chlorophyll a and POC concentrations along with BOD significantly increased with decreasing distance to the rivers in the east, suggesting that the observed spatial water quality decline was triggered by riverine runoff and not by the countercurrent-located Santa Marta. Nitrate, nitrite, and chlorophyll a concentrations significantly increased during upwelling, while pH and water clarity decreased. Generally, water quality in TNNP was close to oligotrophic conditions adequate for coral reef growth during non-upwelling, but exceeded critical threshold values during upwelling and in relation to riverine discharge.     

Spatial distribution patterns of the soft corals Alcyonium acaule and Alcyonium palmatum in coastal bottoms (Cap de Creus, northwestern Mediterranean Sea)

Current knowledge on the abundance and distribution patterns of different soft coral species is relatively limited when compared to other benthic suspension feeders such as gorgonians and hard coral species. To overcome this scarcity of information, the distribution patterns of the soft corals Alcyonium acaule and Alcyonium palmatum were investigated in northwestern Mediterranean benthic communities over a wide geographical (60 km of coastline) and bathymetrical (0–70 m depth) extent using a remotely operated vehicle. A. acaule was the most abundant species in the study area with highest recorded density of 18 col m^?2 found at depths of 35–45 m in areas that are directly exposed to strong near-bottom currents. Conversely, A. palmatum was only found as scattered solitary colonies at greater depths in soft bottoms, with maximum density of 2.4 col m^?2. Medium and large colonies of A. acaule were preferentially found on sloping and vertical rocky bottoms where they form dense patches. High-density patches of A. acaule were preferentially found on vertical rocky bottom, while isolated colonies were preferentially observed on coralligenous substrata as well as on flat soft and maërl substrates. A. acaule biomass distribution showed highest values between 40 and 45 m depth, and between 60 and 65 m depth. This suggests that deeper populations are formed by colonies that are bigger than the equivalent shallower ones. Although both species are almost genetically identical, ecologically they are very different. For this reason, conservation plans should consider the differential ecological traits shown by these two soft coral species.